Preparation of Transient Simulation Data for PSCAD Relay无尽的永恒
Ca Study of Manitoba Hydro D72V Transient Relay Testing
Randy Wachal
Manitoba HVDC Rearch Centre
Ding Lin
Manitoba Hydro
Abstract: This paper prents the procedure for efficiently preparing the data necessary to perform a PSCAD Relay [1] transient simulation study for relay testing. An existing 1300+ bus ASPEN Oneliner [2] phasor bad system model was converted to an equivalent 4-bus PSCAD Relay model. A comparison of steady state 60 Hz results for both 3 pha and single line to ground faults verify that the transient and phasor system models are equivalent. The transient model can be ud with confidence to generate transient fault waveforms simply not possible to develop with phasor bad simulation method. Transient fault waveforms were ud to investigate the operations of the forward and rever ground directional overcurrent elements of the Nxtpha L-PRO line protection relay.
Keywords Relay Testing, Transient Simulation, PSCAD Relay, System Equivalent, ASPEN Oneliner (ASPEN)
1. INTRODUCTION
Transient testing of protection relays with waveforms of the same quality and frequency respon of the voltage and current waveforms the protection us from the system PT and CT is becoming increasingly important [3]. This is true especially as the speed and complexity of the digital protection system increas. A form of dynamic testing has been developed bad on the steady state phasor solutions. The pre-fault, fault and post fault steady state phasors would be calculated using a phasor bad simulation program like ASPEN or PTI PSS/E. The prefault, fault and post fault phasors for voltage and current would be converted into time domain waveforms and then simply concatenated together to create a type of dynamic changing time domain waveforms. This dynamic STATE testing ignores any transient effects when the fault was applied or removed and works reasonable well there is a high level of filtering applied by the protection relay.
A more accurate reprentation of the transient waveforms is to simulate the power system using a time domain simulation program to directly develop the transient fault waveforms. The waveforms
include all of the transient effects. One of the difficulties encountered is developing the data necessary for time domain or PSCAD Relay simulation. In many utilities there is a large databa of phasor bad simulation models, which have been developed over a period of many years. This paper illustrates the process of converting and validating the existing phasor bad ASPEN system model into a
transient PSCAD Relay model. A ries of transient fault cas to reprent various fault conditions and current flows are described. In general, transient testing allows a much more complete suite of cas to be ud for testing, including such items like applications of the fault at any pha angle, variation in telecommunication and breaker operating times. A t of fault cas was utilized for transient testing of line protection for a new 230 kV transmission line (D72V) recently commissioned in Manitoba Hydro system.
2. DEVELOPMENT OF SYSTEM MODEL
2.1 System Model
PSCAD/Relay ca for the system under investigation was developed from an ASPEN ca. ASPEN is a fundamental frequency fault program, ud routinely by Manitoba Hydro for protection st
udies. Manitoba Hydro maintains a relatively large (1300+ bus) system model in ASPEN. The conversion of a large system into a transient simulation can be a significant effort. For the D72V test program, the ASPEN system model was converted into a 4-bus PSCAD Relay ca using equivalent voltage sources at each bus to reprent the remaining system. A comparison between results from the PSCAD Relay ca for three pha and single line to ground (SLG) faults at each bus and the ASPEN simulation was performed with matching results. This validation verified the system equivalence techniques ud to reduce the system size and the system model conversion.
2.2 Procedure for ASPEN Equivalence Network and Conversion
The Manitoba Hydro ASPEN system models consist of approximately 1300 buss. This system was converted to a 4-bus system including eight 3-pha transmission ctions and three 6-pha transmission ctions. A 6-pha line ction includes the mutual coupling effects when two 3-pha circuits share the same tower. The PSCAD Relay Ca developed for this testing is shown in Figure 1.
A step-by-step illustration of the process of developing equivalent sources at the 4 bus locations within the ASPEN program is described in details in its on-line help menu as well as its ur manual (Reference 2: Appendix
G). This process is relative easy and would require less than an hour of time for any ur with some familiarity of using the ASPEN program. Prior to proceeding to conversion to PSCAD, it is important to ensure the faults results generated in the full ASPEN system are the same as the same fault ca in the equivalence or reduced ASPEN system
Once the equivalent electrical system is developed and validated in ASPEN, this data is ud to develop the PSCAD Relay ca. It is possible to develop a PSCAD Relay ca from a blank sheet but it is much quicker to lect a ba PSCAD Relay from the prepared examples. This example ca is then modified into the study ca. Additional Transmission lines, breakers and voltage sources can be added by copy and paste commands. The following steps illustrate the process.
Step 1: Select the appropriate PSCAD Relay Example ca.
Step 2: Enter the Positive and zero quence impedance for each voltage source. Add additional voltages
sources as required.
Step 3: Enter the transmission line data parameters either using the direct R, X, B values from the ASPEN
model or if available, transmission tower geometry
and conductor information in a PSCAD traveling
transmission line traveling wave model. If mutual
coupled transmission are utilized remember to input
transmissions as 6 or more conductor elements.
PSCAD supports mutual coupling of up to 20
conductors. Add additional transmission lines as
required.
Step 4:Add Coupled Pi branch ctions to accommodate the fictitious branch data generated by the ASPEN
Equivalence procedure. This data will have ries R
and X but no shunt B data.
Step 5: Run the PSCAD solutions with no faults applied and adjust the voltage source magnitude and angle
to give the desired prefault bus voltages and power
flow.
At this point the PSCAD Relay system model is ready for comparing steady state faults results with results from ASPEN ca or to proceed with development of transient test waveforms. Permanent single and three-pha faults were applied and compared with steady state solutions with ASPEN results for the same ca.
2.3 Validation of Transient System Model
In order to compare PSCAD and ASPEN results it is important to remember ASPEN simulation results can be shown as pha or quence quantities and that the results are steady state in nature. PSCAD provides a time domain voltage and current waveform similar to what can be measured on the power system. In order to compare ASPEN and PSCAD results, the time domain waveforms must be converted to a phasor equivalent. Within PSCAD there are “RMS” measurement blocks and 3 pha on-line
SLG Fault at Dory
Voltage (V0) at:
ASPEN PSCAD** Differenc e between ASPEN & PSCAD** % Error
between ASPEN &
PSCAD*
* Dory Bus 2 12.6 13.18 0.58 4.6% Ridgeway Bus 4 2.9 4.174 1.27 43.9% Rosr Bus 1 5.4 6.675 1.28 23.6% St Vital
Bus 3 1.6 2.561 0.96 60.1%
Current (3I0):
Bus 3 R33V I1 28 17.54 -10 -37.4% Bus 2 D36R I2 297 412.9 116 39.0% Bus 3 D72V I3 248 298.6 51 20.4% Bus 2 D72V I4 248 296.4
48 19.5%
Bus 4 D36R I7 297 414.5 118 39.6% Bus 2 D13R
I8 387 424.9 38 9.8%
图片唯美伤感I fault
34114 36250
2136 6.3%
烈士寄语Figure 2: PSCAD FFT Block with Sequence Outputs
FFT processing blocks that can provide positive, negative
and zero quence information. Figure 2 shows the PSCAD FFT block.
The results for comparison between the full (1300+ Bus) ASPEN and the reduced (4-bus) PSCAD system illustrate a clo match for the positive and zero quence voltages, branch currents and fault currents. Samples of results for a SLG and 3-pha fault are prented for a fault on Dory bus are prented in Table 1 and 2. Results are prented in both absolute value and % error. Care in interpreting results is required. For example, in the SLG fault ca the zero quence voltages at the non-faulted buss show a large percentage error, while the absolute values are within a very acceptable 1.3 volts. Table 1: Single Line to Ground Fault at Dory Bus
3 Pha F ault at Dory
我的创业史Voltage (V+)
at:
ASPEN PSCAD Difference between ASPEN & PSCAD % Error
between Aspen & PSCAD Dory Bus 2 0 0 00.0% Ridgeway Bus 4 36.1 36.8 0.7 1.9% Rosr Bus 1 23.4 24.5 1.1 4.7% St Vital
Bus 3 45.1
45.77
0.67
1.5%
Current (I+):
Bus 3 R33V I1 974 963 -11-1.1% Bus 2 D36R I2 2177 2223 46 2.1% Bus 3 D72V I3 1759 1779 20 1.1% Bus 2 D72V I4 1759 1782 23 1.3% Bus 1 R23R I5 1600 Bus 3 R32V I6 963 933 -30-3.1% Bus 4 D36R I7 2177 2221 44 2.0% Bus 2 D13R I8 2491 2609 118 4.7%
I fault
37484 37150
-334
-0.9%
The minor differences can be attributed to the following: 1. 2. 3. 4. Equivalence: Results for ASPEN
system are 1300+ buss, while PSCAD are for the 4 bus system.
Note: When a 4-bus ASPEN system was solved the results between ASPEN and PSCAD are within 1%. Prefault load flow: ASPEN has fault calculations performed from a flat start position, while PSCAD solves the system. Even when the power flow is reduced to zero, or near zero, the effects of the transmission line charging are prent. Transmission lines are not identically modeled. ASPEN us a coupled pi model with lumped R, X and B values. PSCAD calculates the traveling wave parameters for the line bad on geometrical conductor configuration and conductor data. The 60 Hz lumped parameters calculated by PSCAD are clo but not precily the value ud in ASPEN.
Table 2: Three-Pha Fault at Dory Bus
Mutual Coupling. The mutual coupling for some other transmission lines on the same right of way as D72V were not modeled in PSCAD but in ASPEN, becau the geometry data for the lines was not readily available.
清汤面怎么做3. Development of Transient Test Cas
3.1 The Problem
平息的近义词
D72V is a new transmission line with portion of it constructed on the same towers of an existing line, and on the same right of way (ROW) with some additional existing lines. During state simulation testing of the relay, the directional ground overcurrent elements of the relay were giving some questionable results for some current reversal conditions due to mutual coupling effect. It was not clear whether the operation of the fast reacting elements is affected by the unrealistic simulation of the transition between states, or by different fault conditions such as fault inception angle or prefault line loading. The nsitivity of the forward and rever ground overcurrent elements 67F and 67R of the Nxtpha L-PRO relay on the new D72V line was the focus of this transient testing program.
3.2 The Test Plan
A number of PSCAD/Relay simulations were performed to generate the required testing waveforms. An “A” pha to ground fault was applied at the Ridgeway end of D36R, at Fault Location F3 on Figure 1, in order to produce a forward rever current flow on D72V. The application of fault angle was modified from 0 to 180 degrees in 30-degree steps; and the power flow from Dory to St. Vital on D72V was adjusted from 0, 100 and 200 MW. In addition, the telecommunications delay between line D36R breaker opening at the Ridgeway, B1 shown in Figure 1, and the breaker opening at the Dory end, B2 shown in Figure 1, was lected at 30 or 100 mc. This t of tests was performed
using the multiple run feature of PSCAD, generating a total of 42 test cas. Each test ca generated the three voltage and three current signals required for transient testing of the Dory and St Vital D72V protection system. An example of the waveforms is shown in Figure 3.
Initially 200 MW is flowing on D72V. A SLG fault is applied at Ridgeway end of the D36R line. The voltage and currents prented are recorded at the Dory end of D72V. When the fault is applied, the D72V relay at Dory end es rever current. The Ridgeway breaker opens 50 mc (3 cycles) after the fault, changing the direction of the current as en at the Dory end of D72V. The breaker on D36R remote from the fault opens 30 mc after the local end (approximately 2 cycles) and removes the fault current flow from D72V.
自由资本主义
The faults waveforms were ud for real time transient testing of the D72V. The overall development time for PSCAD Relay Ca development, validation with ASPEN steady state and transient ca study plan was a couple of days, with the bulk of effort in the validation testing.
3.3 Results of the Testing Program
The transient waveforms were played into a Nxtpha L-PRO relay configured with the appropriate tting D72V
海伦凯勒读后感Figure 3: Sample Transient Test Waveforms Voltage and Current at D72V Dory
files. Figure 3 illustrates the transient waveforms generated by PSCAD Relay, which were played into the relay. Figure 4 shows a t of sample waveforms recorded by the L-PRO relay. The operation of the 67F and 67R elements was verified over a large number of cas during a one-day t
esting period. The transient testing program confirmed that the relay operation was not dependent on the prefault loading, fault inception angle or the protection telecommunication delay on the faulty line, but the level of positive quence component of the fault current has an effect on the operation of the directional ground overcurrent elements.
4. CONCLUSIONS
Transient simulation testing of protection offers many advantages over the more traditional methods. Since the transient waveforms produced reprent realistic voltage and current waveforms that the protection es in rvice, the overall confidence in the testing results is greatly incread. The process to develop a transient system simulation model from a phasor-bad system is not difficult.
With PSCAD/Relay, it was possible to develop a study system that produced the same results as a fundamental frequency program. Once the positive and zero quence networks were confirmed, the development of particular study cas of interest was performed. The PSCAD/Relay generated waveforms were injected into the protection system using a real time transient playback system, allowing a thorough confirmation of the relay performance. The development of a transient test plan can be performed within PSCAD Relay with minimum effort. The transient test waveform
s can be ud to verify the relay performance with confidence for either single or GPS bad end-to-end testing.
The operation of the Nxtpha L-PRO relay was verified over a large number of cas during a one-day laboratory testing period.
5. REFERENCE
[1] “PSCAD/Relay Installation and Operations
Manual”, Manitoba HVDC Rearch Centre, Aug
2001.
[2] “ASPEN Oneliner V2001 Ur’s Manual”
[3] M.S. Sachdev, T.S. Sidhu, P.G. McLaren, Issues
and Opportunities for Testing Numerical Relays,
IEEE Power Engineering Society Summer Meeting,
Seattle, Washington, USA, 16 – 20 July 2000.
