1、 2020-1-A Study on Digital Substation Modelling using RTDS Simulator Luoyun Xu1,2,Haiyu Li2,Zhongping Zhang1,Yuhao Zhou1,Haizhou Huang1 1Huadian Electric Power Research Institute,Hangzhou,China,2The University of Manchester,Manchester,UK ABSTRACT:In order to develop a strategy and architecture for a
2、ssessing the performance of substation protection and control(P&C)functionalities,this paper first introduces the IEC61850 based digital substation modelling in RTDS simulators.The developed models include two generic 400kV double busbar substations and a whole double busbar model with 11 bays using
3、 the specific substation parameters.The experimental test platform has been implemented with one vendor bay,which includes a differential relay,a distance relay,a bay control unit and an HMI connected to the Station Bus.Some preliminary tests have been carried out for assessing the substation protec
4、tion and control functions.KEY WORD:IEC61850;Digital Substation;RTDS Simulator;Modelling;Experiment Test 1 Introduction In 2003,IEC 61850 standard has been introduced to facilitate the interoperability of intelligent electronic devices(IEDs)from different manufacturers.However,the growing integratio
5、n of renewable energy resources and new types of loads into the grid has facilitated the development of smart grid technologies.The risks and costs of replacing substation secondary system equipment(e.g.protection and control devices)or introducing new/digital equipment are high.Therefore,in the UK,
6、both National Grid and Scottish Power Energy Networks have started to invest digital substation technologies.National Grid has started various initiatives to set up the Architecture for Substation Secondary Systems(AS3)project.The project has designed a simple,long life IEC 61850 based digital subst
7、ation architecture,which is expected to be low-cost,flexible and robust enough to cope with equipment outages 1.Scottish Power Energy Networks has deployed full digital substation architecture for the Future Intelligent Transmission Network Substation(FITNESS)project 2 to assess the functionality an
8、d interoperability for multi-vendors Intelligent Electronic Devices(IEDs).To achieve a highly reliable communication network,both HSR and PRP redundancy networks are considered.To assess the performance of different substation architecture,various IEC 61850 testing platforms using the Real Time Digi
9、tal Simulator(RTDS)have been developed in 3-5.Traditionally,protection lab tests require wired signal outputs from the RTDS.However,the RTDS Technologies has developed the Giga-Transceiver Network Communication Card(GTNET)to provide a communication link to/from the simulator via Ethernet.The GTNET c
10、ard can be used to model an IED,and it interacts with external IEDs based on IEC 61850.Therefore,the wired connection for input/output signals can be replaced by the ethernet connection,which reduces the complexity of the IEC 61850 configuration process.The engineering process of configuring an IEC
11、61850 based substation has been described in 6-8.In 3,an approach based on the Eclipse Modelling Framework has been proposed to automatically generate C code files from a given SCD file.The C code files can then be used for low-cost embedded IED devices,e.g.microcontrollers,where runtime performance
12、 is critical.This paper presents the research of the digital substation modelling with RTDS simulator.Three different types of the model are analysed and simulated.A survey of SCL configuration tools are conducted and these tools are compared.The experimental platform has been implemented and the su
13、bstation performance under different conditions can be assessed and evaluated.2020-2-2 Substation Modelling To accurately model a specific 400kV transmission substation,Fig.1 illustrates the single-line diagram(SLD)of the substation,which consists of one bus section bay,two bus coupler bays,two tran
14、sformer bays,three shunt reactor bays and six feeder bays.As an RTDS simulator has a limited capability of simulating a power system,three models with different numbers of bays have been developed using the specific substation parameters.The details are described as follows.Fig.1 Single-line diagram
15、 of the 400kV substation 2.1 Model 1：Generic double busbar substation with three bays Fig.2 shows the SLD of the developed Model 1,which is a generic 400kV double busbar substation.The model includes a bus coupler bay,a feeder bay and a transformer bay.The transformer has three windings of 400kV,275
16、kV and 13kV,respectively.A shunt reactor is connected to the 13kV tertiary winding for reactive power compensation.Model 1 has a total of 10 disconnectors and 3 circuit breakers.Bus Coupler BayFeeder Bay Transformer Bay400kV275kV13kV Fig.2 Single-line diagram of Model 1 400kVMain 1 Main 2Reserve 1 R
17、eserve 2400kV Feeder275kV FeederLoad demandLoad demandLoad demandLoad demand275kV13kV Shunt ReactorSourceTransformer Bay Feeder Bay Bus Coupler BayCTVT Fig.3 Circuit diagram of Model 1 in the RTDS The corresponding RTDS circuit model is demonstrated in Fig.3.The bus coupler bay in Fig.3 represents t
18、he left bus coupler in Fig.1.The 400kV feeder in Fig.3 has been modelled using the parameters(i.e.line impedance and capacitance)of the WHSO/SEAB feeder in Fig.1,which has the longest line distance(70km)among other feeders.The power exported from the WHSO/SEAB feeder has been simulated by a 3-phase
19、resistor in parallel with a 3-phase reactor(at a lagging power factor of 0.97).The transformer bay is based on the SGT2 transformer bay in Fig.1.The rating of the 13kV shunt reactor is 60 MV Ar.The other feeders in Fig.1 have been aggregated as passive shunt components,i.e.resistors in parallel with
20、 reactors.The active power demand of the substation is around 1600 MW,and an AC source has been placed to balance the power flow.By changing the line or transformer parameters,Model 1 can be re-configured to represent various combinations of the feeder and transformer bays in Fig.1.Model 1 has 51 el
21、ectrical connection nodes in total.In addition,CTs and VTs will be added based on the experimental test requirements.2.2 Model 2：Generic double busbar substation with four bays Fig.4 illustrates the SLD of Model 2,which consists of Model 1 and a bus section bay.This model has 13 disconnectors and 5
22、circuit breakers(one for the 13kV shunt reactor).Fig.5 shows the RTDS circuit diagram.Model 2 has 66 nodes in total.2020-3-Bus Section BayBus Coupler BayFeeder Bay Transformer Bay400kV275kV13kV Fig.4 Single-line diagram of Model 1 400kVMain 1 Main 2Reserve 1 Reserve 2400kV Feeder275kV FeederLoad dem
23、andLoad demandLoad demandLoad demand275kV13kV Shunt ReactorSourceTransformer Bay Feeder Bay Bus Coupler BayCTVTFaultBus Section Bay Fig.5 Circuit diagram of Model 1 in the RTDS 2.3 Model 3：Whole double busbar substation with eleven bays The whole model covers all bays of the 400kV digital substation
24、,which includes 2 bus coupler bays,6 feeder bays,2 transformer bays and one bus section bay.This model has 174 nodes.As one RTDS rack can only solve up to 144 nodes,two racks are required to run the model.Model 3 is divided into two subsystems:the left side(with 90 nodes)and the right side(with 84 n
25、odes),respectively.The left subsystem has main busbar 1(M1)and reserve busbar 1(R1),and the right subsystem has main busbar 2(M2)and reserve busbar 2(R2).One RTDS rack is assigned to solve one subsystem,and the two racks provide real-time signals simultaneously.The M1(or R1)and M2(or R2)are connecte
26、d via a low-impedance transmission line.This is the only way to achieve multi-rack simulations according to the RTDS manual as shown in Fig.6.The voltage difference between the two subsystems has been reduced to 0.005 pu by reducing the line impedance.This cross-rack impedance is not allowed to be t
27、oo small,since RTDS simulators require relatively constant states at the cross-rack ends(at least within a simulation time step of 50s)to solve multiple subsystems simultaneously.Lower impedance will have a faster time constant,which could lead to a quicker dynamic response than the RTDS simulation
28、time step(50s).Cross-rack endrack#1rack#2rack#3 Fig.6 RTDS subsystems connection 3 Lab Test platform Based on the specific 400kV substation,a closed-loop test platform has been developed by connecting an RTDS simulator,AMUs,DMUs(circuit breaker controllers),a power amplifier,Ethernet switches,relays
29、 and GPS clocks.Fig.7 illustrates the overall system.Fig.8 shows the circuit diagram of substation model with some function modules in the RTDS.Station BusProcess Bus 1(PB1)AMU1AMU2MP1Process Bus 2(PB2)MP2Inter Bay PB/Measurement BusBCUDMU1DMU2DMU3AMU3HMINotes:MP1:differential relay.MP2:distance rel
30、ay.BCU:bay control unit,which includes DAR,BUP and breaker failure protection(RBRF).DMU is referred as CBC.DMU1 is connected to BCU for DAR and BUP.DMU3 is reserved for future use.Amplifier RTDSCB status(on or off)Tripping and close signals for CBBay1 CT(Ia,Ib,Ic and In)&VT(Va,Vb,Vc and Vn)Master Cl
31、ock Timing distributorIRIG-B or 1-PPS3-phase voltages and 3-phase currentsElectric cableFibre optic cableInterface cubicle AInterface cubicle BFig.7 Single-line diagram of the 400kV substation As shown There are two independent Process Busses(PBs),one Interbay Process/Measurement Bus(MB)and one Stat
32、ion Bus(SB).PB1 and PB2 are used for the local bay SV/GOOSE exchange for MP1 and MP2,respectively.The MB has VT measurements from other bays for CB synchronisation,and the SB has IEC 61850-8-1 MMS messages as well as the GOOSE exchange 2020-4-between the relays in a same bay or across bays.Bay contr
33、ol unit(BCU)has included the overcurrent backup protection(BUP),the delayed automatic reclose(DAR),synchronization and breaker failure protection(RBRF)functions.Therefore,the BCU is connected to PB1(for BUP and DAR),the MB(for CB synchronization)and the SB(for RBRF and station-level control).Feeder
34、1(with bay solution)Remote End(with generator PV control)Fault inserted on the feederCTVTBay 1 Bay 2 Bay 3CTVTCB CB Fig.8 Substation model in RTDS As shown in Fig.8,the RTDS simulates the primary plants and generates the analogue signals for the CT&VT in the Feeder Bay 1.As the signals produced by R
35、TDS is small(e.g.within 10V),a power amplifier has been used to amplify the small signals and send the signals to AMUs(refer to Fig.7).In addition,the RTDS also transmits the status(0 or 120V)of the CB position to DMUs.The AMUs(or DMUs)transform the analogue signals into SV(or GOOSE)packets and send
36、 the packets to the process buses where the MP1(differential relay),MP2(distance relay)and BCU are connected.If a fault occurs,MP1 will send a trip signal(in GOOSE)to DMU1,and DMU1 will generate an analogue signal to open the CB simulated in the RTDS.As shown in Fig.7,a master clock has been used to
37、 generate the timing signals(in IRIG-B,but can be configured to 1-PPS)for all equipment.A distributor has been used to increase the number of timing signals from the master clock.4 Case Studies 4.1 Fault injection test with DAR&CB synchronisation For the substation model as shown in Fig.8,a fault(ph
38、ase-ground or phase-phase)can be applied to the feeder 1(61.6 km),and the fault can be inserted at various locations on the feeder.Tab.I summarises the test results with two representative fault events.From the results,MP1 has output the trip signals within the limit of 30 ms as defined in the techn
39、ical specification.In addition,MP1 has estimated the similar fault locations to the locations simulated by RTDS.As MP1 sent cross-trip signals to MP2,MP2 also tripped DMU2,which increased the protection reliability.Tab.I Fault injection test results Fault Type Location Duration Fault RMS Current(rec
40、orded by MP1)Trip Time of MP1 Estimated location Phase A to ground(with 1 fault resistance)&Phase B to ground(with 1 fault resistance)30.8 km(middle)0.3s Phase A:10.832 A Phase B:11.664 A Phase C:0.797 A(at CT secondary side)24 ms 30.6 km Phase A to Phase B(with 1 fault resistance)61.6 km(end)0.3s P
41、hase A:5.369 A Phase B:6.001 A Phase C:0.628 A(at CT secondary side)23 ms 61.4 km As the applied faults were transient faults,the BCU reclosed the CB after 20 seconds according to technical specification.The closure has involved the CB synchronisation,and the BCU could successfully close the CB with
42、out introducing large dynamic impacts on the substation.From the CT currents shown in Fig.9 and Fig.10 which are monitored by RTDS,the transient CB closure currents are much smaller than the fault currents.(a)3-phase fault currents(b)CB closure currents 0 0.03333 0.06667 0.1 0.13333 0.16667 0.2Time(
43、s)-20-100102030AmpsIBURA1 IBURB1 IBURC10 0.03333 0.06667 0.1 0.13333 0.16667 0.2Time(s)-0.1-0.0500.050.1AmpsIBURA1 IBURB1 IBURC1 Fig.8 CT secondary current with fault at mid-point 2020-5-(a)3-phase fault currents(b)CB closure currents 0 0.03333 0.06667 0.1 0.13333 0.16667 0.2Time(s)-10-50510AmpsIBUR
44、A1 IBURB1 IBURC10 0.03333 0.06667 0.1 0.13333 0.16667 0.2Time(s)-0.4-0.200.20.4AmpsIBURA1 IBURB1 IBURC1 Fig.9 CT secondary current with fault at feeder end 4.2 CB failure test with GOOSE exchange between RTDS and BCU In order to test the CB failure(CBF)protection function of the BCU,the RTDS simulat
45、or has been configured as a virtual bay to directly receive the CBF signal(in GOOSE)from the BCU over the SB.If the received CBF signal is on(i.e.Logic 1),the RTDS will open the CB in the adjacent Bay.Tab.II gives the test result with the CBF delay time set at 200 ms.Tab.II CB failure protection tes
46、t result Fault Type Location Duration CBF Trip Time CBF Reset Time*Phases A&B to ground(with 1 fault resistance)30.8 km(middle)0.3s 204 ms 96 ms If the protection relay fails to open the CB during a fault,the BCU will send a back tripping signal to other bays via SB.Fig.10 GOOSE data captured from B
47、CU Fig.10 also shows the CBF signal captured on the SB.In Fig.10,the time period between the first CBF ON time(t=8.7143s)and the first CBF OFF time(t=8.8098s)is 95.5 ms,which is similar to reset time recorded by the BCU(i.e.96 ms)in Tab.II.4.3 Interoperability test with RTDS-simulated SV In addition
48、 to receiving/sending GOOSE messages,the RTDS simulator can produce IEC 61850-9-2-Light Edition(LE)SV packages.The SVs can be time synchronised using an external 1-PPS signal.Therefore,the MP2 in the remote(see Fig.7)has been configured to receive SVs from the RTDS via PB2.Fig.11 demonstrates the SV
49、 reading from the MP2 panel.The fault injection test result in Tab.III also shows that the MP2 can trip successfully with RTDS-simulated SVs.Fig.11 MP2 reading with RTDS-simulated SV packets Tab.III Fault injection test for RTDS-simulated SVs Fault Type Location Duration Fault RMS Current Trip Time
50、Estimated location Phases A&B to ground(with 1 fault resistance)35.2 km(middle)0.3s Phase A:9.997 A Phase B:10.141 A Phase C:0.294 A(at CT secondary side)19 ms 35.6 km 4.4 HMI remote control Fig.12 shows the HMI for its controlled bay.The HMI can also be used to monitor other bays in the substation.
