Power Systems Communications Implementation of IEC61850 in a Substation Environment

Transcription

1 Power Systems Communications Implementation of IEC61850 in a Substation Environment 26 October 2009 Reference VEE Revision 0

2 Document Control Document ID: DOCUMENT1 Rev No Date Revision Details Typist Author Verifier Approver 0 20/10/2009 Document Created Team Team Team

3 Contents Section Page 1. Introduction IEC Standard Peer-to-Peer Message (GOOSE) Process Bus Interface True Interoperability 2 2. Generator Protection Chosen Relay for Generator Protection Key Benefits and Features of G60 Relay Wiring Diagrams for Generator Protection 4 3. Transformer protection Key Features User Benefits Single line diagram of how relay connected to the transformer 8 4. Switchgear Protection Busbar Protection The important issues of switchgear protection can be summarized The requirements for good protection kV Busbars Intelligent Electronic Device (IED) Functional Block Diagram (GE Multilin) Substation Monitoring (Human Machine Interface) Differential Busbar Protection Line Protection Line Distance Protection IED61850 Application Distance IED Communications Application Substation Communications Network (IED61850 Network) Implementation of IEC Redundant Network Conclusion 20 REVISION 1 PAGE i

4 1. Introduction The aim of the project is to design the protection solution for the given system which has to be in compliance with IEC61850 standard. It is also required to work out the infrastructure of the next generation power system communications including the communication and telecommunication protocols. Figure 1: Given system REVISION 1 PAGE 1

5 1.1 IEC Standard IEC is the global standard for communication in substations. It enables integration of all protection, control, measurement and monitoring functions within a substation, and additionally provides the means for high-speed substation protection applications, interlocking and intertripping. The comprehensive implementation facilitates integration of the relays into IEC based Substation Automation Systems and at the same time it allows the interface with different vendors' Merging Units over the IEC Process Bus. It combines the convenience of Ethernet with the performance and security which is essential in substations today. IEC enabled relays are fitted with an integral Ethernet card providing both copper and fiber Ethernet. No external adaptors or data concentrators are necessary and only standard Ethernet equipment such as switches and substation grade switches etc are required. 1.2 Peer-to-Peer Message (GOOSE) Generic Object-Oriented Substation Event (GOOSE) messages can be used for interlocking, disturbance recording cross-triggering, breaker failure protection tripping, directional comparison bus protection and many other advanced applications, thus eliminating extensive hardwiring in equipment bays and so reducing the cost of implementing advanced distributed protection and control schemes. The implementation of the IEC GOOSE messaging provides faster end-to-end transfer than using hardwiring. 1.3 Process Bus Interface Analog interface units (or Merging Units) located in the substation yard interface with conventional or non-conventional instrument transformers and send the sampled current and voltage values over fiber, thus significantly reducing (actually eliminating) the copper wires between the substation primary equipment and the protection, control and measuring devices. 1.4 True Interoperability One protocol is all that is needed in the substation. Costly gateways and split path communications are thus avoided. Peer-to-peer messages, control commands, disturbance files transfer or event driven reports are interleaved on a single Substation Bus network. Multiple clients can be integrated, allowing authorized operators and engineers to interrogate and control the substation IEDs. The Substation Configuration Language defined in the standard represents a leap in the engineering process related. The self-descriptive nature of IEC compatible IEDs means that system integration and commissioning are easier. Standardized data classes and services mean IEC enabled IEDs can operate seamlessly in multi-vendor environments. REVISION 1 PAGE 2

6 2. Generator Protection Industrial and commercial power systems may include generators as a local source of energy. These generators supply all or part of the total energy required, or they provide emergency power if the normal source of energy fails. The application of generators can be classified as single-isolated generators, multiple-isolated generators, unit-connected generators, cogeneration generators, and induction generators. Generator protective schemes vary depending on the objectives to be achieved. Generator protection requires the consideration of many abnormal conditions that are not present with other system elements. The abnormal conditions that may occur with generators include: Overheating Stator (due to overload or loss of cooling) Rotor (due to overexcitation, loss of cooling) Winding faults Stator (phase and ground faults) Rotor (ground faults and shorted turns) Overspeed and underspeed Overvoltage Loss of excitation Motoring Unbalanced current operation Out of step Subsynchronous oscillations Inadvertent energization Nonsynchronized connection 2.1 Chosen Relay for Generator Protection The relays selected for generator protection is manufactured by GE Multilin. Figure2: GE Multilin G60- Comprehensive protection for generators 2.2 Key Benefits and Features of G60 Relay Complete IEC Process Bus solution providing resource optimization. Secure high-speed protection elements for complete generator protection, compliant with IEEE C REVISION 1 PAGE 3

7 Reduced relay to relay wiring and associated installation costs through highhigh-speed inter-relay communications. Redundant architecture for dependability and security security. Networking interfaces 100Mbit Fiber Optic Ethernet, RS485, RS232, RS422, G.703, and C Multiple Protocols - IEC61850, DNP 3.0 Level 2, Modbus RTU, Modbus TCP/IP, IEC60870 IEC , Ethernet Global Data (EGD). (EGD) 2.3 Wiring Diagrams for Generator Protection orm the followin followingg ANSI functions if configured using standard scheme as This relay can perform shown below in single line diagram: Figure 3 For our particular system single line diagram showing VT & CT connections is given below: FILE C:\DOCUMENTS AND SETTINGS\DURA65282\LOCAL LOCAL SETTINGS SETTINGS\TEMPORARY INTERNET FILES\CONTENT.OUTLOOK\KZ6DO78L\POWER FILES POWER SYSTEM COMMUNICATION REPORT REVISION 0 0.DOCX 26 OCTOBER 2009

8 Generator Protection 87 81O/81U 67N 59N 50G/51G 27P/27TN 24 GE G60 Multilin IED CT/VT Connection Circuit Breaker Trip 110V VT Metering Generator Protection GE G60 Multilin IED 200MVA Generator Protection Employed 87 81O/81U 67N 59N 50G/51G 27P/27TN 24 22kV/330kV Transformer Figure 4

9 Three CT s and one VT were used to implement the generator protection and the protection functions employed were: ANSI Device Number Function 87 Generator Stator Differential 81O Overfrequency 81U Underfrequency 67N Neutral Directional Overcurrent 59N Neutral Overvoltage 50G Ground Instantaneous Overcurrent 51G Ground Time Overcurrent 27P Phase Undervoltage 27TN Third Harmonic Neutral Undervoltage 24 Volts Per Hertz REVISION 1 PAGE 6

10 3. Transformer protection Transformers are high capital cost assets in electrical power systems. Elimination of all electrical and mechanical stresses desirable to preserve transformer life is impractical. Adaptive techniques to measure and alarm in such instances and advise on service duty can help to schedule preventive maintenance. Internal faults are a risk for all transformers. With short circuits dissipating the highest lacalized energy. Unless cleared quickly the possibility to rewind windings reduces and core damages may become irreparable. The MiCOM P642, P643 and P645 from AREVA address all the issues - preserving service life, and offering fast protection for transformer faults. The P642 incorporates differential, REF, thermal, and overfluxing protection, plus backup protection for uncleared external faults. So we decided to use P642 as it is cheap and suitable for our substation design. 3.1 Key Features High-speed transformer differential protection. A proven 2 nd harmonic current scheme is used Simple setting wizard requires only nameplate data Restricted earth fault (REF) boosts trip sensitivity Voltage, frequency, thermal and overfluxing elements CT, VT, trip circuit and self-supervision: Patented CT supervision ensures no trip for CT or wiring failures Integrated backup overcurrent per winding Readily interfaces to multiple automation protocols, including IEC User Benefits Universal IED for all transformer configurations Simple to specify, set and commission Backup and logging of faults Protection, control, measurements and recording in one device REVISION 1 PAGE 7

11 3.3 Single line diagram of how relay connected to the transformer CTs on both side of the transformer are for differential protection. Grounding CT is to tell weather the connection is delta/star or star/delta Overcurrent backup protection indicates from dotted red line.

12 REVISION 1 PAGE 9

13 4. Switchgear Protection 4.1 Busbar Protection Busbars are one of the most important components in a substation. There can be open busbars in an outdoor switch yard or contained inside a metal clad cubicle restricted within a limited enclosure with minimum phase-to-phase and phase-to ground clearances. Busbars form an electrical node where many circuits come together, feeding in and feeding out power. It is very clear that for any reason the busbars fails, it could lead to shutdown of all distribution loads connected through them, even if the power generation is normal and the feeders are operating normally. 4.2 The important issues of switchgear protection can be summarized Loss very serious and sometimes catastrophic Switchgear damaged beyond repair Multi-panel boards not available off-the-shelf Numerous joints Air enclosure Dust build-up Insect nesting Ageing of insulation Frequency of stress impulses Long earth fault protection tripping times 4.3 The requirements for good protection The successful protection can be achieved subject to compliance with the following: Speed Limit damage at fault point Limit effect on fault stability Selectivity Trip only the faulted equipment Important for busbars divided into zones Stability Not to operate for faults outside the zone Most important for busbars Stability must be guaranteed Reasons for loss of stability Interruption of CT circuits imbalance Accidental operation during testing Tripping can be arranged two-out-of-two Zone and check relays REVISION 1 PAGE 10

14 kV Busbars This is the 330kV busbars that require busbar protection. 4.5 Intelligent Electronic Device (IED) IEDs selected to protect the 330kV busbars. REVISION 1 PAGE 11

15 4.5.1 Functional Block Diagram (GE Multilin) Substation Monitoring (Human Machine Interface) REVISION 1 PAGE 12

16 4.6 Differential Busbar Protection The busbars will be protected by two IEDs; the purpose of the two IEDs is to provide reliability and backup protection. If one IED fails, one busbar will still be protected. REVISION 1 PAGE 13

17 REVISION 1 PAGE 14

18 REVISION 1 PAGE 15

19 REVISION 1 PAGE 16

20 5. Line Protection This part of the report will be covering the transmission line protection of the substation. The main faults that can occur on the transmission lines are: Line to Line Line to ground Double line to ground Three phase line to ground These faults can be caused by simply things such as birds, snakes, bushfires, and branches falling on to the line. They can also be caused by lightning and deterioration of insulation. This section will be focusing on the four transmission lines for the 2 buses which have to lines each as shown below. Figure 5.1 Four transmission lines 5.1 Line Distance Protection In order to protect these four lines two relays from different vendors has been chosen. The first relay chosen is the ABB REL 670 Distance relay (figure 2). The REL 670 relay is fully IEC61850 complaint and features Control, monitoring and protection integrated in to the one IED. This relay is also chosen because of its maximum reliability and performance optimized for Figure 2. ABB relay transmission overhead lines and cables. REVISION 1 PAGE 17

21 The way in which The ABB REL 760 relay is connected to the transmission line is in the Dual breaker configuration instead of a simply configuration which uses 1 VT and 1 CT. The Dual breaker configuration uses 2 VTs and 2VTs it will cost more but is a lot more reliable. The connection scheme can be seen in figure 3. The second relay used in the system is the GE D90Plus (figure 4). The D90Plus is also fully IEC61850 and also features back up protection such as time over current. The D90Plus is also selected because of the fact that it can use fibre optic communication. The D90Plus is connected on the same scheme as the ABB in which it is connected in a Dual breaker scheme with 2 VTs and 2 CTs.(Figure 5) Figure 4. GE D90Plus Figure 5. D90Plus connection 5.2 IED61850 Application When all the relays have been place in the substation, the relays from the two vendors are connected together by the fibre optic link on the process bus as can be seen in figure 6. One each bus we have 4 CTs and 4VTs with 3 circuit breakers with one of those circuit breakers being used by both relays. REVISION 1 PAGE 18

22 REVISION 1 PAGE 19

23 5.3 Distance IED Communications Application This report covers the transmission line protection of a new substation but Figure 7 shows a larger picture of the system with the top half being the new substation and the bottom half being another substation xxx Kilometres away, the top substation uses a ABB relay while the bottom substation uses a GE relay and the two are connected by a fibre optic cable xxx Kilometres away. REVISION 1 PAGE 20

24 REVISION 1 PAGE 21

25 6. Substation Communications Network (IED61850 Network) 6.1 Implementation of IEC Redundant Network Redundant bay controller has default settings Local servers store all real time data operate substation in the event of network hack, security breach or corrupted data transmitted to control centre can only take instructions from the local HMI Require passwords A SMS message will be sent using a mobile phone or other similar device via a message broker in an emergency REVISION 1 PAGE 22

26 REVISION 1 PAGE 23

27 7. Conclusion The IEC61850 standard will become the most widely used standard for substation communications. The main features being interoperability, reliability (easy to replace IED s with different vendor IED s), advanced protection, advanced automation and control (smart grid compatibility), advanced metering and easier/simplified human interface with the power system. REVISION 1 PAGE 24