with auto-configuration of station monitoring through IEC 61850 and CIM

UPTEC E 18 027

Examensarbete 30 hp 7 September 2018

Digital secondary substations

with auto-configuration of station monitoring through IEC 61850 and CIM

Johan Wistedt

Teknisk- naturvetenskaplig fakultet UTH-enheten

Besöksadress:

Ångströmlaboratoriet Lägerhyddsvägen 1 Hus 4, Plan 0

Postadress:

Box 536 751 21 Uppsala

Telefon:

018 – 471 30 03

Telefax:

018 – 471 30 00

Hemsida:

http://www.teknat.uu.se/student

Abstract

Digital secondary substations with auto-configuration of station monitoring through IEC 61850 and CIM

Johan Wistedt

This thesis explore the possibility to automate a process for configuration of

secondary substations monitoring and control. By using a network information system (NIS), information of secondary substations can be extracted, such as feeder naming, primary equipment type, rating and model. From this information an automated process of configuring the secondary substation is possible, which open up the possibility to cost-efficiently digitalise the distribution grid.

In the project, the standard IEC 61850 for configuration of communications of intelligent electrical devices was used to automate and standardize the process. The process starts with a extracted IEC 61970 CIM file from the NIS. The IEC 61970 CIM file is converted into a IEC 61850 SCL file through an system engineering tool. The configuration is based of information from the NIS, where the models and types of the equipments decides what type of functionality that is needed for the secondary substation. With help of the created SCL file hardware and human-machine interface (HMI) was configured, creating a full functional system for the secondary substation monitoring and control equipment.

The usage of 400V capable input module together with bus couplers, configured in IEC 61850, lowers the configuration needed for the hardware. The usage of SCL files also helps automate the creation of HMI for the secondary substation through IEC 61850 based tools in SCADA software. Creating views of both single-line diagrams as well as digital representation of the secondary substation outgoing feeders with measured values on display.

The result of the project helps show NIS information is sufficient and standards mature enough to allow an almost fully automated system. Lowering the total time spent on each stations configuration to around two hours. Leading the way for future development of automating software for configurations of the secondary substations.

Ämnesgranskare: Mikael Bergkvist Handledare: Nicholas Etherden

1 Svensk Sammanfattning

En ¨okad produktion i distributionsn¨atet samt en infrastruktur som har st¨orre beroende av avbrottsfritt eln¨at har f¨or¨andrat den traditionella bilden av Sveriges eln¨at. Sveriges eln¨at best˚ar av tre distinkta delar; generation, transmission och distribution. I detta traditionellt radiell uppbyggda eln¨at var behovet av

¨

overvakning p˚a distributionsn¨atet l˚ag. Detta kombinerat med h¨og kostnad f¨or m¨atutrustning gjorde att majoriteten av sveriges n¨atstationer f¨or att trans- formera ner sp¨anningen till 400V fas-till-fas inte ¨ar utrustad med m¨atutrustning kopplad till kontrollcentraler.

Denna inst¨allning har nu ¨andrats med det nya trenderna i eln¨atet. P˚a grund av st¨orre framtida konsumtion och produktion i distributionsn¨atet s˚a hotas n¨atet av stora pikar i effektfl¨odet i n¨atet. Fl¨odet av effekten blir ocks˚a sv˚arare att f¨orutse d˚a delar av distributionsn¨atet kommer producera mer effekt

¨

an vad de konsumerar, vilket leder till att effekt kommer fl¨oda fr˚an distribu- tionsn¨atet till transmissionsn¨atet. Allt detta kan leda till effekter p˚a elkvaliteten,

¨

overbelastning p˚a komponenter i distributionsn¨atet samt i v¨arsta fall avbrott.

F¨or att l¨osa detta problem har planer p˚a ett digitaliserat distributionsn¨at diskuterat. D¨ar st¨orre ¨overvakning och kontroll av distributionsn¨atet beh¨ovs.

Det tillsammans med smarta m¨atare kan g¨ora n¨atet intelligent d¨ar energi-tunga processer k¨ors n¨ar ett ¨overfl¨od av energi produceras. F¨or att uppn˚a denna digi- talisering s˚a beh¨over en stor del av n¨atstationerna i distributionsn¨atet utrustas med smarta m¨atare och kontrollenheter. D˚a antalet n¨atstationer i Sverige ¨ar ett par hundra tusen kr¨avs en automatiserad process av konfigurationen av dessa m¨atare och kontrollsystem.

I detta projekt skall m¨ojligheten av att skapa en automatiserad process f¨or konfigureringen av n¨atstationers m¨at- och kontrollinstrument unders¨okas. Pro- cessen ¨ar t¨ankt att g˚a fr˚an ett n¨atverk informationssystem av ett omr˚ade till slutgiltig konfiguration av en n¨atstation, med underliggande l˚agsp¨anningsn¨at, med konfigurerad h˚ardvara och god illustrerande HMI (Human-Machine Inter- face) f¨or stationen. Processen skall vara s˚a automatiserad som m¨ojlig och f¨or att uppn˚a detta skall informationsmodellerna IEC 61870 CIM (Common in- formation language) och IEC 61850 anv¨andas. Detta tillsammans med IEC 61850 standardisera l¨osning g¨allande konfiguration av h˚ardvaran och HMI ska- par m¨ojligheten av en automatiserad och standardiserad process som kan spara b˚ade tid och pengar.

Contents

Abstract

1 Svensk Sammanfattning

Nomenclature

2 Introductions

2.1 Description and background . . . . 7

2.2 Purpose . . . . 8

3 Theory

3.2 Netbas . . . . 10

3.3 Information Models CIM and IEC 61850 . . . . 10

3.3.1 Extensible Markup language (XML) . . . . 11

3.3.2 Common Information Model (CIM) . . . . 11

3.3.3 Substation Configuration Language (SCL) . . . . 13

3.3.3.1 Substation Configuration Description (SCD) . . 14

3.3.3.2 System Specification Description (SSD) . . . . . 15

3.3.3.3 IED Capability Description (ICD) . . . . 15

3.4 IEC 61850 . . . . 15

3.4.1 Logical Node . . . . 18

3.4.2 Manufacturing Message Specification (MMS) . . . . 20

3.4.3 Helinks Substation Tool Suit . . . . 22

3.5 Intelligent electronic device (IED) . . . . 23

3.5.1 Remote Terminal Unit (RTU) . . . . 24

3.5.2 Bus couplers (remote I/Os) . . . . 24

3.5.3 Axioline F . . . . 25

3.6 Station HMI and SCADA . . . . 25

3.6.1 SCADA . . . . 26

3.6.2 HMI . . . . 27

3.6.3 Zenon Energy . . . . 28

4 Implementation

4.2 Configuration of substation using Helinks STS . . . . 32

4.2.1 Low Voltage function library . . . . 33

4.2.2 Name Space . . . . 34

4.3 Configure hardware with the Netbas-based SCL file . . . . 36

4.3.1 Setting up bus coupler with I/O modules . . . . 37

4.3.2 The I/O modules . . . . 37

4.3.3 Configure the bus coupler with the CIM-based SCD file . 38 4.3.3.1 Mapping I/Os . . . . 40

4.3.4 The RTU AXC F 1050 . . . . 41

4.4 Automated generation of HMI Zenon Energy through CIM-based

SCL file . . . . 42

4.4.1 Communication through IEC 61850 in Zenon Energy . . . 42

4.4.2 Frame for future HMI . . . . 43

4.4.2.1 Chronological event list (CEL) . . . . 44

4.4.3 Automatic drawn single-line diagram from SSD file . . . . 44

4.4.4 Creating digital representation of secondary substation through pre-build symbols . . . . 45

5 Result and discussion

5.1.1 Single-line extraction from CIM . . . . 50

5.1.2 SCL Creation in Helinks STS . . . . 50

5.1.3 Hardware . . . . 51

5.1.3.1 Feeder automation solution . . . . 52

5.1.3.2 Smart I/O based solution . . . . 52

5.1.4 HMI . . . . 53

6 Conclusion

7 Future work

8 References

9 Appendix

Nomenclature

CEL Chronological Event List CIM Common Information Model DA Data Attribute

DO Data Object

HMI Human-Machine Interface I/O Inputs and Outputs

ICD IED Capability Description file

IEC International Electrotechnical Commission’s IED Intelligent Electronic Devises

IID Instantiated IED Description file LN Logical Node

LV Low Voltage

MMS Manufacturing Message Specification MV Medium Voltage

NIS Network Information System PLC Programmable Logic Controller RTU Remote Terminal Unit

SCADA Supervisory Control and Data Acquisition SCD Substation Configuration Description file SCL Substation Configuration Language SSD System Specification Description file UPS Uninterruptible Power Supply XML Extensible Markup language

2 Introductions

2.1 Description and background

Most secondary substations in Sweden do not contain any control or monitor- ing equipment. When most of Sweden’s secondary substations was installed the need of such safety feature was considered obsolete. This was because of the old grid structure where the grid was divided into three main components:

the generation, transmission and distribution. The radial power feed of such a system was more stable which made investment in measurement equipment too expensive and not necessary. The secondary substations are located in the distribution part of the grid and is used to transform the voltage from trans- mission voltage to the general distribution voltage of 400 V phase-to-phase[1].

The situation of the distribution grid has changed the last couple of years. To- day it is more local production in the distribution grid, such as wind and solar power. This together with more consumption in form of charging of electrical car batteries affects the stability and capacity of the distribution grid [2]. This creates the need of more monitoring and control of the distribution grid, a so called digitisation of the grid.

With the digitisation of the distribution grid, it is possible to monitor the power flow in the grid by using communication between meters in substation, houses, small production facilities and industrial consumers. Enabling more accurate lo- cation of faults and cause of fault as well as quicker restoration of power through better information for the field technicians. Things such as heating and high consumption processes in factories are more controlled and predictable by the power flows in the grid than randomly occurring events. The value of having monitoring of the distribution network is not only for the digitisation of the distribution network. It can also help securing the stability of the grid. By knowing the power and energy flow, critical areas of the grid can be discovered easily. The maintenance will be more pro-active since fault can be discovered before they causes problems if one monitor the load rate on equipment and ca- bles. Investment can be made in the part of the grid where it is most needed.

However, most of the substation only need basic monitoring in form of voltage and current measurement. From these measurement it is possible to obtain most of the needed information for the secondary substation in the distribution network, such as power flow [3], harmonics and current/voltage imbalance.

To be able to update to a digital distribution network many old secondary substations need to be updated with monitoring and control equipment. Vat- tenfall owns around 40 000 secondary substation and to be able to digitalise most of these the process needs to be as automated as possible. A manual con- figuration of each station is too costly in both time, personal and money. The process needs to be a process that ensures consistency and automated engineer- ing solutions.

To achieve automation, the IEC 61970 CIM (Common Information Model) standard for network information and IEC 61850 standard for configuration for intelligent electronic devices at electrical substations will be used to keep the process as standardised as possible. The tools for configuration and the hardware present in the station shall be as automated as possible with a direct and clear work flow, where human input shall be as limited as possible. An additional requirement is the need for field technicians to report documentation errors easily in order to ensure updated and correct information in the network information system (NIS).

2.2 Purpose

The purpose of this project was to evaluate the possibility of a fully automated process of converting information from a network information system into a fully configured secondary substation. The process can be divided into four main parts:

• The process of going from the network information system through a CIM file to a system engineering tool for IEC 61850.

• Use information from the CIM file to configure a secondary substation in IEC 61850 standard communication protocols in the system engineering tool.

• From the file created in the system engineering tool configure hardware to measure current and voltage on the low voltage side.

• From the same file create a HMI (Human-Machine Interface) for the sec- ondary substation.

Figure 2.1: Work process of the automation for secondary substations in this project

The evaluation of the automation shall be discussed and any problems iden- tified. The project will only try to prove the concept and will therefore not result in software who will have a working automatic configuration. Instead it will act as a proof of concept, to evaluate if NIS (Network information system) information is sufficient and if standards are mature enough to allow a fully automated system.

3 Theory

3.1 Secondary Substations

The secondary substations are usually a point on the grid where the voltage is transformed down to 0,4kV phase to phase [4]. In Vattenfall’s secondary substa- tion, the voltage is transformed from the medium voltage levels (20kV or 10kV) down to low voltage (0,4kV) for residential areas and out to the customers. The stations are made up of different components where the transformer is the most important and central of them all. In addition to the transformer there are safety equipment such as fuses and switches.

Figure 3.1: Secondary substation cabinet

In old stations safety equipment are usually not monitored or controlled from an operation central. This is partly because of previously high cost to do so, but also because of the traditional radial power feed did not require detailed information in real time for the medium- and low voltage grids. This led to a low interest of keeping track on the low voltage side power quality. The in- terest in power quality has lately become more relevant with the increase of distributed energy sources producing electricity locally in the distribution grid and the society increased dependence on electricity. This has sparked research in so called smart grids where more focus is put on monitoring the low voltage side of the grid and controlling the secondary substations in a more direct way, which increase the potential limit on how much renewable energy that can be installed without affecting the power quality for the system [5]. This together with ”smart meters” [2] in houses for the customers that are remotely moni- tored and knows the local energy consumption, the houses can use energy from

the grid for function such as heating when the overall demand is low [6]. This smooth out the daily power consumption curve of the system and more power is used when production is high.

Since most of the old secondary substations do not have a system controlling or monitoring them, a solution for an upgrade to station control and monitor- ing need to be as simple as possible to configure and install. The general way to supervise a substation is to use wired remote information exchange with a SCADA (Supervisory Control and Data Acquisition) system with a standard- ised communication protocol. In this paper the focus will be on the information model of CIM and IEC 61850. In the station there will be a number of sen- sors connected to a RTU (remote terminal unit). The RTU will act as our IED (intelligent electronic devices) (see Helinks STS) and will communicate with the SCADA system. The RTU together with I/O will work almost like a PLC (Programmable logic controller) and will be configured with help of the SCL (substation configuration language) file from Helinks. The RTU with the I/O modules has a number of inputs and outputs were data from sensors are collected or data transferred out to a control, for example a controllable switch.

3.2 Netbas

Netbas developed by Powel is a program used by Vattenfall as their Network Information System for the grid. In Netbas information about equipment of the grid and its position are presented. This creates a grid map of the grid network and with parameters for the equipment, the possibility to simulate the power flow in the system is achieved. This combined with information, such as cable type, name of outgoing groups in substations and different ratings makes Netbas a good tool for keeping information about the grid. The information can also be exported as CIM (Common Information Model) files, where the information is shown in a XML (Extensible Markup language) instead of only in Netbase.

This is used to get information about the grid to other tools and software.

3.3 Information Models CIM and IEC 61850

Common Information Model, or for short CIM and IEC 61850 are both infor- mation model used in the power electronic sector and describes grid systems or part of grid system, such as a substation. CIM are defined by class definitions and references while IEC 61850 are hierarchical with logical nodes (LN) and data objects (DO), that are described in section 3.4. The IEC 61850 informa- tion model has a file, describing language and representation of the IEC 61850, in form of the SCL file, while the CIM itself is a file type. Both CIM files and SCL files are based on the Extensible Markup language (XML) structure and are in many ways similar to each other. Both can be used to extract information about the grid and recreate the information into a single line diagram. However, the two information models and files are used in the industry for two distinct purpose. CIM is used as an information model of the general grid of an area,

containing information about equipment’s model type, parameters and position in a coordinate system. This enables a creation of a map of the grid [7] with all information needed to simulate the grid in a software. The SCL file on other hand is used for configurations of IEDs substations. Describing the different IED that is in a substation and how they communicate with each other and to different HMIs (human machine interfaces). These intelligent electronic devices are responsible for the safety feature in a substation and are usually protection relays or control terminals, but can also be remote terminal units (RTU) or programmable logical controllers (PLC). In general any instrument capable of sending/receiving information can be considered an IED.

3.3.1 Extensible Markup language (XML)

Extensible Markup language is a common used markup language with a set of rules that makes it readable for both humans and computers. The XML language is a string of characters. The characters forms a code with help of start-, end- or empty-elements tag [8]. Elements are defined with help of a start-tag and an end-tag with the element content in between the tags. An element can also be defined with only an empty-element tag. All tags start with

”<” and end with ”>”. The start tag and empty-element tag can also have attribute as seen in 1.

Type Example Tags Example Attributes End- and star-tag <Name> John

Johnson </Name>

<Fuse rdf:ID=” 8d32ee34”>

”Content” </Fuse>

Empty-element tag <line-break /> <img src=”oneline.jpg” />

Table 1: Table shows examples of XML structure, in the example of attributes one attribute is an .jpg file and the other is an ID code

3.3.2 Common Information Model (CIM)

The Common Information model CIM is an information model defined in the IEC 61968 and the IEC 61970 standard to describe the electrical network or grid. The CIM is based on a unified modelling language that is based on inher- itance between classes, compared to the IEC 61850 sequential and hierarchical structure. This makes the CIM file structure less predictable than the SCL file.

The CIM file describes the whole gird by relationships between classes. This make it hard to extract an specific area of the grid, such as a substation, since the equipment in the substation might not be in direct inheritance of the class

”Substation” in the file.

The CIM file structure of inheritance can be described as having three different relationships between the classes [8], where a class can have an association-, a generalisation- or an aggregation relationship with another class. When the class has an association relationship with another class, it can be defined as

that the two classes ”has an relationship” with each other meaning ”they have something to do with each other”. When two classes has a generalisation rela- tionship, it can be defined as the class ”is in a relationship” with the other class or that ”one class is also the other class”. An aggregation relationship can be defined as the class ”is a part of a relationship” with the other class meaning there is an hierarchy where ”one class can is an element underneath another class”. This complex relationship can more easily be seen in figure 3.2.

Figure 3.2: Relations between classes in CIM

As seen in figure 3.2 the class Substation, VoltageLevel and Bay are all in a generalisation relationship with EquipmentContainer. A Bay represent an out- going group in the secondary substation. This means that the class Equipment can be in an aggregation relationship with the class EquipmentContaioner and therefore in the file it “points” at an EquipmentContainer. But if one follows the ID of the EquipmentContainer the EquipmentContaioner will be a Substation, Bay or a voltage level as seen in figure 3.2. In the same way a VoltageLevel can point at a Bay and the Bay can point at a Substation, but they are all Equip- mentContainers as well. The same way as the classes Bay, VoltageLevel and Substation all are Equipmentcontainer, all ConductingEquipment are Equip- ment. The ConductingEquipment also has a association relationship with the class Terminals. The numbers next to the line indicating how their relations association roles are defined. For instance the Terminal class has an association to ConductingEquipment with cardinality 1, which means that Terminal must have an association to an instance of ConductingEquipment. The ConductingE- quipment however has a cardinality of 0..* which means that they can have 0 or more association with different Terminals.

The CIM structure can roughly be divided into four “information areas”. One is the already discussed EquipmentContainers that can be described as the name suggest ”information of containers of equipments”, such as a bay in a substa- tion. The second is Equipment that contains information of all the equipment

in the grid. The third is the Asset that contains more specific information for example equipment. Here the information about models, types and material of equipment can be extracted. Lastly the class Location. Location has informa- tion about position and which coordinate system to use. A general map of the different classes in the CIM file can be seen in figure 3.3.

Figure 3.3: Overview of the CIM file structure, figure by Vincent Gliniewicz at Vattenfall R&D

3.3.3 Substation Configuration Language (SCL)

Substation Configuration Language or for short SCL is the substation config- uration description language for IEC 61850 standard. Its structure is based on Extensible Markup language (XML)[9]. The SCL file contains five different parts which describes the different aspect of the substation and its communi- cations. These are Header, Substation, Communications, IED and data types template. The header contains information about the identity version of the SCL configuration file and other basic details relevant as information about the file. The substations contain the entities of the substation such as interconnec- tions, devices, bays, voltage levels and other functionality, describing the station in detail. The Logical node that represent functionality related to objects are also referred in the substation part.

Figure 3.4: Simple figure of a network tree in IEC 61850

The communications sections deal with the communications points or access points for the different IED:s in the system when trying to access them. This is done with help of different sub networks and access points for the IED:s which creates a network tree, as in figure 3.4, of the systems communications. The IED section describes the configuration of the IED containing logical devices, logical nodes, report control blocks and what data an IED publish and reports or receives with Generic Substations Events (GOOSE and GSSE). Lastly the data type template defines logical nodes and data types according to IEC 61850-7-4

& 7-4. The data template can be divided into subcategories LN Type (such as the example MMXU, XCBR), DO Types, DA (data attribute) Type and Enum Type. The IEDs will be extensively described in 3.5.

The SCL file can be split up into sub files for different applications depending on information [9], content and stage in the engineering process. These are Sub- station Configuration Description file (SCD), System Specification Description file (SSD), IED Capability Description file (ICD), Configured IED Description file (CID), Instantiated IED Description file (IID) and System Exchange De- scription file (SED). In this project the focus will lie on SCD, SSD and ICD files.

3.3.3.1 Substation Configuration Description (SCD)

The SCD file is describing a complete substation with both substation details, communications details, IED information and the data types template. The SCD file can be described as a combination of a SSD file and several ICD files where the minimum number of ICD files is one.

3.3.3.2 System Specification Description (SSD)

The SSD file contains the specifications of the substation regarding single line diagrams and functions linked to the different levels of the substations. The single diagram is organised in a hierarchy where the substation is highest and elements of the substation branches down from it as seen in figure 3.5. This is one of the difference between how a SCL and a CIM file describe a substation.

The organised hierarchy in the SLC file is replaced with a flat structure of cross references, albeit with some inheritance rules in the CIM file.

Figure 3.5: Hierarchy of the substation in the SSD file

3.3.3.3 IED Capability Description (ICD)

This file contains the capability of the IED it describes. The file is usually created by the manufacturer of the hardware, but in this project it is created with help of Helinks STS. The file contains an IED section which describes the logical devices present in the IED. It can also contain optional communication section and optional substation part which contains the physical devices that correspond to the IED in question.

3.4 IEC 61850

The standard for configuration of communications of intelligent electrical devices (IED) at substations IEC 61850 is an international standard from the Interna- tional Electrotechnical Commission’s (IEC), Technical Committee 57 [9], [10].

The development of the standard was based off the need of interoperation be- tween different devices in the substations. Most stations were locked to only devices and equipment from one producer of equipment [11]. By standardise the configuration of the substations with help of IEC 61850 and using the com- munications defined in the standard, it is possible to use multiple producers of

equipment in one system as long they use the IEC 61850 standard. By using the standard, the design of substations automation system can also be done in a more structured approach. The main part of the standard was first published between 2002 and 2005.

Figure 3.6: IEC 61850 approach for applications and communications, inspired from [10] (page 16)

By making the communication independent from the applications the stan- dard has a possibility to always keep up with innovations in the field of com- munications. The data model used by the standard is an abstract data model [10]. It is this abstract data model that makes it possible for the communi- cation to always be up to date and the standard can be mapped to different protocols, since the data model is separated from the method of communica- tion. The protocol is currently mapped to the standard MMS (Manufacturing Message Specification), GOOSE (Generic Object-Oriented Substation Event), SMV (Sampled Measured Values). In this project focus will lie on the MMS protocol.

The standard demands free allocations of the different functions (needed in the control and measurement system of the substation) to all IEDs [10]. This creates a need for interoperability between the IEDs so a function can be performed in one IED but reside in another IED, which force the IED to communicate with each other. The interoperability between the IEDs makes the functions distributed and the functions can be assigned to three different levels in the substation: the bay level, the process level and the substation level. Theses dis- tributed functions can also be dissolved into Logical Nodes, see Logical nodes.

Figure 3.7: Logical Nodes in different levels in IEC 61850 and the communication between them

Substation level

In the substation level functions processing alarm/event handling, interlocking, station wide voltage control and data in HMIs [12].

Bay level

The bay level functions usually takes care of control, protection and automatic process [11]. Taking care of most functions not directly related to raw inputs from I/Os and functions directly related to a power equipment.

Process level

The process level contains functions directly related to direct inputs from I/Os or functions that has a direct connection with a power equipment in the substa- tion, Such as switching position for a circuit breaker or position of a tap changer.

The standard uses the Substation Configuration Language (SCL) as file rep- resentation of the configuration which make it possible to keep all information of the IEC 61850 configured station in the same file. As mention before the SCL can be divided into different files with information of a specific part of the configuration, such as the SSD who is a description file of the primary technical elements within a system.

3.4.1 Logical Node

Figure 3.8: IEC 61850 Data modelling, inspired from [10] (page 24)

Logical nodes or LN for short represent the building blocks for the data mod- elling in the standard. When breaking down a physical devise (IED) functions, the first step is to break it down into so called logical devices [13]. These logical devices are usually a representation of a specific type of functionality of the IED. For instance, an IED can have the function to calculate the power flow but also a function for unbalanced voltage calculation. The IED can then have two logical devices who has different functions independently of each other and therefore are seen as different devices even when existing in the same physical devise. This make it possible in the communication to treat the different logical devices as different devices, which gives a logical devise its own working mode and behaviour. These logical devices can then be divided into so call logical nodes. These will be the smallest entities and represent the information ex- change [11].

The logical nodes are divided into different grouped depending on what function the logical node has marked with a capital letter as its prefix. These different function groups can be seen in table 2. The groups can also be divided into five general groups; System (L), Interface (I), Unit/Bay level (C,P,R,. . . ), Process/e- quipment level (K,S,X,T,Y,Z) and general use (G,F) [14]. Every group has then different logical nodes attached to themselves for all the functionality needed in the substation. For instance the X class has the logical node XCBR which cor- respond to functionality regarding the information of a physical devise circuit breaker, such as the position of the breaker (closed, open, intermediate-state or error) and more.

Group indicator Logical node groups A Automatic control C Supervisory control

D DER (Distributed Energy Resources) F Functional blocks

G Generic function references

H Hydro power

I Interfacing and archiving

K Mechanical and non-electrical primary equipment L System logical nodes

M Metering and measurement P Protection functions

Q Power quality events detection related R Protection related functions

S Supervision and monitoring

T Instrument transformer and sensors

W Wind power

X Switchgear

Y Power transformer and related functions Z Further (power system) equipment

Table 2: Table of different existing LN groups

The logical node contains different data objects [14] which describes a func- tionality of the logical node. As an example the data object (DO) for the position of a circuit breaker is defined in the LN class XCBR as Pos. All data objects have a capital letter at the start of its name and is recognised with the help of that. The data objects itself is a part of a common data class named with only capital letters. The common data class defines the structure of the DO and multiple DO can have the same common data class. In the example with the position of the circuit breaker the Pos DO has the common data class DPC which is the common data class for controllable double points.

In the common data class, the data attributes (DA) are located which is the last information of what the signal shall contain. It also contains the functional constraint who describe what service the DA is allowed, meaning what the DA shall represent [13], [15]. Because of this the common data class is used to define the relation between their attributes and the functional constraint. In the common data class, the type of data the DA has is also defined, such as BOOLEAN, INT 32 and more. For the example with the circuit breaker the DA to see what position the breaker has is stVal which stands for status value and has the functional constraint ST (Status information). This functional con- straint forces the DA to represent status information whose value may be read, substituted, reported, and logged but shall not be write-able. The DA has also the data type “CODED ENUM” (strings open, closed, intermediate, faulty).

The data signal for the position of the circuit breaker can then be written:

Figure 3.9: IEC 61850 data signal for position of circuit breaker

These signals can then be mapped and transferred to other IEDs or HMIs thought MMS with help of TCP/IP or a Ethernet network. Establishing the communication in the system. These signals are also what is used in the SCADA software environment as variables.

3.4.2 Manufacturing Message Specification (MMS)

One of the way the IEDs and HMIs communicate with each other in IEC 61850 is through MMS (Manufacturing Message Specification). With help of MMS the system has a way to transferring real time process data and supervisory control information between IEDs and HMIs. The advantage with MMS is the possibility to access all IEDs in a system in the same way, regardless of the manufacturer. This is done with help of the abstract data structure. System networks is created with different MMS clients and servers [16], depending on which way the information needs to go. An IED can act as both a server and a client and this allows communications between IEDs. The network is usually a TCP/IP Ethernet network but MMS defines how the information is transported on the network. TCP/IP is a way to package, address, routed, transmit and receive through a network and Ethernet is a link layer protocol network com- monly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN).

In MMS the variables are the most important object type and it is possible to write and read local variables in a remote device. The variables can also be read or written as individual or as a list [17] and contains of its name, data object and data attribute [18]. This is why MMS works so well with the IEC 61850 standard, since the signals in the standard is built in the same way as the variables in MMS. MMS has also only two types of communication services.

One is the ”remote procedure call” [18] or “polling”. This is when a client ac- tively asks the server for a value of a variable or in IEC 61850 a signal from a logical node. This way is good if a value is needed right away for a process but can lead to unnecessary communications on the line, which can overflow the line

with data. The second is the ”event reporting” [17], [18], where the information is not required of the client but rather sent after an event in the server. These events [19] can be decided by different triggers that can range from time triggers to a value change of a variable. These combined with the possible of sending a list of variables is what IEC 61850 usually use for information transferring. In IEC 61850 there is usually four different way information is transferred: polling, buffered report-blocks, unbuffered report blocks and log reports.

Figure 3.10: MMS communication services Remote Procedure Call and Event Reporting

Polling, as mentioned previously, is not so common since the data traffic of a remote procedure call usually is greater than an event report. This can lead to high cost since most network companies receives payment depending on the amount of data traffic. In substations communications will be kept to a min- imum during normal operation and increase only when a operator opens HMI displays or IEDs detects abnormal situations. Buffered report blocks; for every- thing except measurements and unbuffered report blocks; for measurements, is usually what is most common used in an IEC 61850 station and represent event reporting in MMS. These are report list with different signals from logical nodes in the IED defined by the logical node LN0. The different between buffered and unbuffered is that the buffered will save data in the IED if the network gets lost and report a bigger report list after it gets the network back, with historical data from the time the network was lost. Unbuffered report-block however do not do this. Instead if the network is lost and then comes back it will send the latest report with no historical data in it. These report-blocks can be defined with a trigger to keep the data transfer down. One good way is to have a big dead band on measurement and a trig time of changing value. When the mea- surement for instance current, the value taken is normally a value based on the dead band time instead of an instant value, see more in 3.5.2. Log report block is a report block containing an event list and is not so commonly used.

3.4.3 Helinks Substation Tool Suit

Helinks STS software is a IEC 61850 engineering tool developed by Helinks LLC, designed to configure SCL in a graphic work area. The tool consists of three parts which is all drawn as a graphic diagram representation as seen in 3.11.

These three parts can be linked as different part of the SCL file representing the structure of that part of the file (see section 3.3.3).

Figure 3.11: The three different steps in Helinks STS and their graphic diagram representation

The first graphical diagram representation is a single line diagram of the sub- station. This graphical representation in Helinks describes in the SCL file the physical entities in the substation such as transformers, fuses, circuit breaker, switches and more. The single line diagram does also specify the electrical con- nections between the entities [20].

The second graphic diagram representation as the user design in Helinks STS represent the functions containing the logical node used in the substation. This graphic diagram is called the function specification diagram. The functions can be built up from scratch or imported from a function library in Helinks STS [20]. These functions can be pointed at an entity in the substation from the sin- gle line diagram and also linked to a virtual IED. The functions can be defined in three different layers. A layer for the substation where the logical nodes for the HMI are usually configured, a layer for the voltage levels in the substation and one for the bay level. In the bay level LN for the bay level functions are configured. These LNs functions is usually directly connected or related to an physical equipment in the substation. The functions in Helinks can contain one or more logical nodes that are grouped together to point at the same IED or entity from the single line diagram. This results in that the functions in Helinks STS becomes the logical devices in the SCL file after the configuration. The functions can also contain no logic node in them and the program will then see

the function as non-existing. When a single line diagram is drawn the function that is pre-configured for that entity in Helinks will automatically be created in the function diagram and will point at the entity. This can be used to automate the configuration process so that only a single line diagram need to be config- ured by the user and the LN be automatically created for the project. However, the user still need to link the functions so that the logical nodes points to a virtual IED.

The last graphical diagram representation the user need to draw is a system diagram [20]. The system diagram represents the communication part of the SCL file dealing with different communication point for the IED and communi- cations ways for the system. This part does also defines the IEDs used in the system by importing an ICD file of the IED which is a capability description of the IED or by manually creating them in Helinks STS. These imported IEDs can then be implemented as virtual IED, used in the function specifications di- agram. Mapping the LNs to the IED.

When all three diagrams are drawn most of the mapping of the logical nodes towards the IED should automatically be done, but if not, one can manually map the nodes. The software also automatically specific the MMS reports of the system, but the MMS report can be specific by the user if one wants that.

The software can also make GOOSE applications specifications if the project needs it. This is done in a graphic diagram representation where one can create sending functions representing the publisher and reserving functions represent- ing the subscriber. Connections is then established with help of a tool that draws connections between publisher and subscriber. The publisher can be con- figured with signals from the function specification diagram that will be send as a GOOSE message to the subscriber.

3.5 Intelligent electronic device (IED)

In the power electronic sector, a common used name for microprocessor-based [21] system control of power electronic equipment, such as circuit breakers, transformers and more, is the intelligent electronic device (IED). In IEC 61850 IED the name is used for all type of controllers that can somehow process and communicate data according to the standard. These will act as the processing equipment of the functions and will also be responsible for the communications in the IEC 61850 standard.

IED in IEC 61850 usually comes with its own SCL file, the IED Capability Description file (ICD). This file contains the functionality of the IED and is used when the IED is configured for the project. However, in this project no such file exists and the IED is configured without knowing its full potential. In a system the IED can be multiple different types of controllers but in this project, focus will be on the remote terminal unit and bus coupler (remote I/Os).

3.5.1 Remote Terminal Unit (RTU)

The remote terminal unit is like its brother the Programmable logic controller (PLC) a microprocessor that transmit measured and calculated information to a master system such as a SCADA (Supervisory control and data acquisition) system or preforms control functions on equipment from commands from the SCADA system. The RTU usually has a limited HMI (Human-Machine Inter- face) with only LED-indicators for status and error, instead the information is sent to the HMI in the SCADA system. This gives the RTU the roll of data processor and transmitter since the RTU is located in the station [21] and report back information of the station to a command central. This remoteness of the RTU is what difference it most from the PLC where the PLC usually are close to the SCADA and use drift central wired communication channels while the RTU use wireless communication. Previously, the PCL also was more suitable for control algorithms or control loops but modern RTU and PLC are getting more and more similar where no big different is present between them, except where they are used.

3.5.2 Bus couplers (remote I/Os)

In this section the bus coupler shall not be confused with the bus coupler used in substations with a double bus system to help with the transfer operation when switching bus. The bus coupler in this project is an IED and can be described as an secondary substation RTU with limited function processing capability.

These bus couplers are usually also called remote I/Os and are an extension of the local communication bus which in this project extends to cover IEDs along radial lines from primary substation. This gives the option to have I/Os col- lecting data further away from the local RTU which can be beneficial for larger substations or be used where the data collection do not need to be processed and raw data from I/Os can be used.

The bus coupler can potentially have less processing power as the normal RTU and usually needs to only handle the communication from or to the I/Os con- nected to it. This makes the bus coupler act more like a transmitter that a processing IEDs. However, sometimes this is beneficial since the configuration of these IEDs usually is simpler and in many cases it is not needed to process data in the IED since the raw I/O data is what is needed from the station. The bus coupler can however have some processing power to help support the IEC 61850 communication. For instance, in IEC 61850 it is common to use dead bands [22] for analogue measurements to save data volume of measurements.

The dead band helps lowering the amount of possible values for an analogue signal. Most analogue values in IEC 61850 uses this dead band values with the signal name end mag.f/i (where f stands for float and i for integers, depending on what data type used). This instead of the spontaneous value with the signal name end istMag.f/i.

In this project the used bus couplers allowed some data processing to give a static value on the signals rangeC.min.f (minimum value of the value range), rangeC.max.f (maximum value of the value range) and db (factor for determine the dead band). These static values is then used to calculate the dead band (DB) as seen in equation 3.5.1 [22]. The difference between the two curves in- sMag.f/i and mag.f/i can be seen in figure 3.12. The static values will affect the value of the analogue input from the signal mag.f/i of the I/O since the bus coupler now process the value in. When the static value of db = 0, the values for insMag.f/i and mag.f/i will be identical, since the dead band will be 0.

DB = rangeC.max.f − rangeC.min.f

100000 · db (3.5.1)

Figure 3.12: Illustration of difference between the curve insMag.f and mag.f

3.5.3 Axioline F

In this project the hardware used is the I/O block module Axioline F from Phoenix Contacts. The Axioline F has both an RTU and bus coupler with support for IEC 61850 and combined with all different I/O-modules that can be attached, it is possible to create IEDs that has the functions needed for the project.

3.6 Station HMI and SCADA

To process information from IEDs in the system a SCADA and HMIs is needed.

SCADA stands for Supervisory Control and Data Acquisition while HMI stands for Human-Machine Interface. In a grid network the substations present is usually controlled and monitored by a command central. This central will be highest in the command structure and contain one or multiple SCADA system as well as many HMIs. All to give the operator as much monitored information and control as possible to control the grid.

3.6.1 SCADA

SCADA is a system traditionally containing software and hardware elements.

These elements should provide four points [23]:

• Control industrial processes locally or at remote locations.

• Monitor, gather, and process real-time data.

• Directly interact with devices such as sensors, breakers, motors, and more through human-machine interface (HMI) software.

• Record events into a log file.

This to organise the control of the system and give an overview of the system for control personal. SCADA systems is created with different levels in mind where monitoring and control should be possible in the different levels [24]. De- pending on the system different amount of levels can be present. In figure 3.13 the general model of the different levels in a SCADA is shown, where level 0 is sensors, 1 RTUs and 2-4 is different HMIs and computers with SCADA software in different areas of the system.

Figure 3.13: General model for levels in a SCADA system

Modern SCADA has however been more and more digitised and now days the SCADA system highest levels usually only contains computers with SCADA software on them. One of the most important aspect of a SCADA is its event and alarm processing where some events need to pass through an HMI and approved by humans but other should be happening right away. The upper command system shall then not interfere with the basic levels of the SCADA.

Instead it shall be possible for communications between only RTUs. This to keep the system from human made errors or keep short response time.

3.6.2 HMI

Human-Machine interface is how a machine present information to humans.

This can be complex layouts on a computer, simple pointer instrument or LED- indicators depending on the HMI. Depending on where in the system the HMI is placed the complexity of it usually varies. For instance, in a secondary sub- station the HMI is usually limited to LED status indicators of the RTU or bus coupler and a manual disconnector, while in a larger substation the HMI can be a computer screen with limited control options. In the command center the HMI is usually more advance with multiple screens and control options.

Figure 3.14: Local HMI in a secondary substation

3.6.3 Zenon Energy

Zenon Energy is a SCADA software developed by Copa Data for operation control of substations and grid system and is the SCADA system used in this project. The advantage with Zenon Energy is its tools for IEC 61850 configured stations. These tools have the capability to read SCL files and automatic help construct the interface for the screen and help with the driver configurations for the IED used in a project based on the IEC 61850 standard. Zenon Energy contains also tools to make dynamic single-line diagrams and also tools dealing with command processing. The command processing tools helps secure the sys- tem, lowering the risk for human caused errors such as closing a breaker while work on the line is on-going. In this project, Zenon Energy will be used as the SCADA program to develop the HMI for the secondary substation, where the process of creating the HMI should be so automatically as possible.

Zenon Energy contains two main software [25]. One is the editor, containing the workspace where the HMI is built. In the editor the HMI is built through different functions and variables, both internal and external. As the name sug- gests the functions does a function in the program, such as switching screens or writing values. These functions can be linked to different element in Zenon Energy such as buttons or triggered by different events. The variables contain different data types. The signals in IEC 61850 will be variables when they are imported to the workspace. The runtime software is the final product that is created with help of the editor and will be the HMI used in the system. Zenon Energy also have a ”soft PLC” function, allowing for processing of data on the computer where Zenon Energy is installed.

4 Implementation

4.1 Manual CIM conversion

The automation process of converting a CIM file into a SCL file will be com- pared to a manual created conversion. The manual conversion of the CIM file starts with how the CIM file is constructed. The CIM file has less of hierarchy than an SSD file which makes it harder to read since one cannot work down- ward in a tree structure in the same way. The CIM file used in the project also describes the whole grid area with substations of that area. This leads to a file with over 100 000 lines of code. To be able to read out information and create a single line diagram from it a work process needs to be follow. The automation as well as the manually procedure will both use the work process when creating the single line diagram of the system. The structure that will be followed when creating the single line diagram from the CIM is based on the naming of equip- ment, stations, buses and line segment where it all will start with the name of the substation. If one has the official name of a substation it will lead to the substation equipment container with corresponding name from document.

These substation elements is the first step of the creation of the single line di- agram leading to the CIM representation of the secondary substation seen in 4.1.

Figure 4.1: Representation of secondary substation ”NS61968” in CIM

When the substation equipment container if found one can find correspond- ing voltage level to the substation. This is usually three since most station transform the voltage from one level to another and has a neutral voltage level, but can in theory be any number of level. In the project the station with the id name in this report “NS61968” was the one converted. This substation con- tains a transformer that transform between 400V and 11K V line-to-line. The