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Virtual relay design for feeder protection testing with online simulation David Celeita Graduate Student Member, IEEE Universidad de los Andes Cra 1 # 18A-12 111711 Bogota, Colombia
[email protected]
Juan David Perez Student Member, IEEE Universidad de los Andes Cra 1 # 18A-12 111711 Bogota, Colombia
[email protected]
Abstract-The aim of this study is to design and implement an accurate virtual model of a basic feeder protection relay. The work focuses on certain sets of ANSI functions and COM TRADE (Std C37.111) to interact with an online simulation subjects to different fault scenarios. The proposed methodology includes robust synchronization between power system simulations and the response of the virtual relay. The results validation integrates a distribution system simulation software running with remote control for time-based simulation, then it reproduces voltage and current signals with the virtual relay operation. The performance is assessed in three cases of study comparing real protection equipment and the operation of the virtual relay at the same fault scenarios. This work is the next step of the attempt to reach a versatile test engine for substation automation systems, including multiple protective virtual devices which reduces costs and allows to assess critical protection schemes.
Index Terms-Substation automation, Protective relaying. Test
ing,
analysis
and
modeling,
Real-time,
Intelligent
electronic
devices.
I.
INTRODUCTION: THE PROGRESSIV E EVOLUTION OF RELAY MODELING
The research of testing and analysis modeling for relaying automation has identified significant challenges, one of them complies testing concerns of substation based protection with realism, flexibility, scalability and open simulation tools [1]. These efforts have been constant objectives in the evolution of protective relaying modeling; for example, DYNA-TEST [2] was originally developed for protection relay applications and it was proposed almost 25 years ago, at the same time when the COMTRADE Standard C37.111 [3] was urgently needed. Protective relaying literature and history show that both, research and industry standardization guarantee the progress of this field and it is consistent with upcoming needs. Al though, one of the main requirements for relay testing with hardware/software integration is low cost usage of commercial computer hardware and system software support [4]. Previous works with relay's modeling have presented ex cellent features in real applications, but always taking into account the limitations of each model [5]; certainly, virtual environments, real-time models and test beds where improved after a decade of the COMTRADE publication, not only for academy courses [6] but also professional training [7].
Gustavo Ramos Senior Member, IEEE Universidad de los Andes Cra 1 # 18A-12 111711 Bogota, Colombia
[email protected]
The interaction between protective devices, relay models and power systems simulations [8]-[11], have shown the effectiveness of these research in various applications such as protection coordination, adaptive protection, reconfiguration and so forth. Most of these studies include at least one or two protective devices, but the progress of this research field requires a higher number of relaying equipment in order to obtain better results [12]. Having not one, but many protective devices (real and virtual relays) will enhance relay testing and that is the proposal of this paper. The work integrates free-distribution software to simulate distribution networks and connects a virtual relay for any switch synchronized with an online simulation. The performance of the designed and implemented virtual relay is compared with previous real-time studies that interact with real protective equipment in different fault scenarios, in order to validate the operation of this tool. First, the function logic and modeling is presented. ANSI functions are designed following the standards for overvoltage, overcurrent and re close sequence. The COMTRADE module is also presented. Section III discusses the implementation of the virtual relay using LabVIEW. Validation and results are assessed in Section IV. Finally, conclusion and further work are presented in section V. II.
RELAY DESIGN AND FUNCTIONS' MODELING
According to the standardization [13] and manufacturers, a set of ANSI functions are selected to develop a virtual model of each function. For feeder's protection the model should include at least overcurrent functions for primary protection (ANSI SOP/SIP and ANSI SON/SIN). Undervoltage and over voltage functions are also integrated in the virtual relay (ANSI 27/59) and the reclosing sequence function (ANSI 79). In order to validate the operation in different fault scenarios, COMTRADE files are recorded following [3], [14] and based on the state machine programmed to the MiCOM P145 [15] with the concepts reported in [16]. The following subsections describe the state machine of each function and the logic operation:
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A. Overcurrent protection and Voltage protection
Time>OeadTime BreakerStatus=False
Active sequence=True
attemptOeadTime BreakerStatus=True
abnormaICondi!ion=False TimeDeadTime
=True
BreakerStatus=False attempt>maxAttemps
eset=True
Active sequence=True
---===:::::��::.::/
Breaker healthy=False
Fig. 2. State machine for auto-recJosing - logic
Fig. 1. State machine for overcurrent and voltage protection - logic
Protection against abnormal scenarios of voltage or current levels must be addressed when protecting a feeder. Three states are defined for undervoltage, overvoltage and overcurrent protection as shown in Fig.l. At the first state, the machine is waiting for an abnormal situation; certainly, in case of an excess of current, the state will move to Stand by state no matters if there is a programmed ANSI function 50 or 51. This will also occur in case of abnormal voltage levels. The stand by state defines if the abnormal situation con tinues for a period of time; nevertheless this time value is previously programmed by the user. There are two conditions to change: • •
If the condition vanished in the progranuned time. If the condition stand still along the programmed time.
In the first case the machine moves back to the first state. Otherwise, the machine will move to a Lockout state if an abnormal condition continued, which means that the pro grammed time was accomplished with the abnormal scenario. To return to the normal state the user should reset the state machine. ANSI functions SOP/SIP, SON/SIN, 27 and 59 will work with the state machine previously presented in Fig.I. B. Reclosing sequence
The state machine to include the auto-reclosing feature (ANSI function 79) in the virtual relay design is proposed tak ing into account three different fault conditions: (1) transient, (2) semi-permanent and (3) permanent. According to literature and experience, most of overhead line faults are caused by lightening and temporary contact with external objects such as trees or wind movement. Since these kind of faults do not last for a long time, the transient nature of this phenomena will possibly allow successful re-energization of the system after the trip of the protection equipment. The first state defines a normal condition, therefore the machine will wait until it receives the reclose signal to begin
a re-energization process. If the breaker is not healthy but a reclose signal is activated, the machine is taken to a lockout state. If a reclose signal is activated and the breaker condition is healthy, the machine will move to the stand by state; Likewise the state machine explained in the previous subsection, stand by states are designed to wait pre-programmed periods of time, so in this case the machine will wait until the dead time passed and then it will decide to which state the machine will continue. Note that the stand by state is the only one which can move to all the states: •
•
•
•
If the dead time has passed and the breaker is closed it will go back to the normal state. If the dead time has passed, and the breaker is opened but it is not healthy, the machine will move to a lockout state. If the breaker is opened, and the machine has tried all the tripping sequence to reclose after the dead time passed, the next state will be the lockout condition. If the dead time has passed, and the breaker is open and healthy, the machine will allow a reclose condition.
In the reclose state, the machine will give the pulse signal to reclose the breaker and it will wait until the reclaim time has passed. Then, a sequence trial is accomplished and the machine goes back to the stand by state. Finally, the lockout state is included in case where the breaker is not healthy or the reclosing sequence has totally passed but the fault remains in the network. This state machine is shown in Fig.2. C. COMTRADE generator and event monitoring
Since the standard was developed by the Power System Relaying Committee, the idea was to take advantage of digital computer based devices capable of record data from transient events in the electric power system. The standard allows the data exchange for analysis and validation of records [17]. With the protective relaying evolu tion, technology has a wide range of purposes that still needs this standard in order to validate real-time simulations and
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Feeder Simulation
----n: I '·T ' x :
Data exchange TCP/IP Undervoltage 27 P
Overvoltage 59 P
Inst. Overcurrent 50 PIN
Overcurent 51 PIN Reclosing 79
50BF Breaker failure
.--
--
--
--
User Front panel
Digital inputs and outputs VIi measurements Fault records IEEE C37.111 (COMTRADE) Lockout monitor Reclosing sequence Manual trip - close
RELAY CONTROL AND
FEEDER
MONITORING
MONITORING
Fig. 3. Virtual relay design - software integration
COMTRADE=True
Data=beforeTrig+afterTrig
COMTRADE created
is enough data to save a COMTRADE file. In this state the machine saves the COMTRADE file and passes to the pre save state as shown in Fig.4. It is important to note that the triggering of this feature and the recorded time are all configured by the user. III.
Fig. 4. State machine for COMTRADE recorder
hardware-in-the-loop testing. Alternative solution of advanced automation, smart fault recorders, power quality tools and tran sient phenomena studies might be focused on COMTRADE files. The state machine to perform a consistent COMTRADE recorder is proposed in order to be activated by a previous user configuration that allows an ANSI function trip to save the transient data. This application includes important aspects of the standard about header, configuration files (.CGF) and sampling rates. The state machine starts in a pre-save state where the machine is saving data in case some event occurs, therefore a pre-fault transient data is always recorded. When an event is triggered (this change of state is activated by the trip of a selected ANSI function), the machine records data after the relay sends the trip signal. The third and last state defines the machine when there
I MPLEMENTATION OF THE V IRTUAL RELAY
A first version of the virtual relay was build to operate with DSSim-PC [18], a recent distribution simulator software and the non deterministic version of the DSSim-RT simulator; This simulator is based in the powerful EPRI's OpenDSS [19] and it can be used as a graphical interface for it. As shown in Fig.3, the online simulation of a distribution system is running on DSSim-PC, while a TCP/IP connection makes possible data exchange between the grid simulation and the operation of the virtual relay. LabVIEW libraries of DSSim-PC are used to synchronize measurement acquisition and time steps (1 ms). In a single computer the user can monitor the distribution system with a meters file previously saved in DSSim-PC, so the user could understand this window as a SCADA of the system. In a second window, the virtual relay monitor and control panel is operating so each function for three phase or single phase protection is configured. In case of any event, the user is allowed to save COMTRADE files for records and post-fault analysis. The function logic designed in LabVIEW are explained in the next subsections:
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VIRTUAL RELAY V 1.0 FOR FEEDER PROTECTION
Protection configuration
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A. TCCs - Overcurrent protection settings
Time current curves (TCCs) have a model equation shown as follows: T
(M::-
1 + L
)
+
C
(1)
Where K, 0: and L are constants corresponding to every standard curve. C is a pure delay applied to the TC curve, T is Time multiplier setting for IEC curves or Time Dial for IEEE curves and M is the proportion of the measured current over the pick up current. The constants used to model the ANSI function 51 are shown in Table.l. The user can select any standard curve or adjust each parameter of the TCC equation. Table I CONSTANTS FOR TIME CURRENT CURVES ACCORDING TO [20] Characteristic Curves Definite time Moderately inverse time Short Time Modified inverse time Modified very inverse time Inverse time Very inverse time Extremely inverse time
K 0.2 0.55 0.2 1.35 1.35 5.4 5.4 5.4
L 0.18 0.18 0.015 0.055 0.015 0.18 0.11 0.03
alpha I I I I I 2 2 2
B. Current and Voltage protection logic
The current and voltage protection logic of the virtual relay works with the activation 2 voltage protection functions un dervoltage (27) and overvoltage (59) and 2 current protection functions instantaneous (50) and inverse time (51). The user
can configure each one of this protection function and decide which one wants to use to protect the feeder with a boolean panel. There is also the possibility of having different protection configuration in every single phase or having the same con figuration in the 3 phases for the implemented ANSI function. Finally the virtual relay has a reclosing sequence function (79). C. Reclosing sequence configuration
To configure this function in the virtual relay there are 4 settings to define. First, the user should give the reclaim time and dead time for each reclosing trial, second the user should configure how many reclosing trials are required. Then, to finish this setting the user must press the activation of this function in the front panel, and finally, the user select which protection function wants to reclose, normally overcur rent functions. The operation of the reclosing sequences will behave as the state machine explained in Fig.2. D. COMTRADE settings and records
In order to save an event, the virtual relay use COMTRADE files using the COMTRADE library of LabVIEW. It is im portant to highlight that this library saves a COMTRADE file according to [21] from 1999, assuming that the PT and CT rates are 1: 1, because the communication with DSSim-PC shares data about voltage and current measurements with the real values in the switch. To adjust the COMTRADE settings, the user must define the path file where the COMTRADE file will save and name of the file. Then the program needs two time windows to know how much data to save before and after the trip, therefore
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these times are taken in milliseconds. Finally in order to avoid rewriting a COMTRADE file, the program will save the name put in the path file in addition with the event time stamp when it was created. E.
User's interface - Virtual relay monitor and control panel
Fig.5 shows the front panel of the proposed virtual relay, which has 4 sub-panels. The biggest one (left side of the figure) there is the configuration panel where parameters for ANSI functions 27, 50P, 51P, 59 and 79 can be configured. At the end of this panel there is a button to graph a TCC curve in the TCC Viewer. The TCC Viewer panel has a button to configure if the user wants to see the current axe in multiples of the pick up current. The next panel is the simulation and COMTRADE configuration where the relay controls the co-simulation link with DSSim-PC (the user selects the node and the switch to be controlled) and the COMTRADE configuration. Finally the last panel (right side in the bottom) voltage and current measurement are presented in RMS values, and there is also a calculation of the sequences voltages and currents in the 3 phases.
This section will present the results of the virtual relay performance under different fault scenarios. The first case assess a basic example that requires two types of protection: overvoltage and overcurrent protection based on the real-time study with hardware-in-the-Ioop for educational purposes [8]. The second case presents the IEEE 13 node test feeder to study the behavior of a recloser connected between nodes N_671 and N_692. And the third case is based on the example IEEE 2422001 study in real-time [12], to compare COMTRADE files recorder by real protective equipment and the proposed virtual relay. Relative error is calculated in case A and case C between values obtained with real-time tests and the virtual relay with the following equation: T
=
I
Xi; Xv v
1*
100%
(b)
(a)
(b)
Fig. 7. (a) Overcurrent COMTRADE switch SW_2 (b) Overvoltage COM TRADE switch SW _3 [8]
IV. VALIDATION AND RESULTS ANALY SIS
E
(a)
Fig. 6. (a) Overcurrent event (b) Overvoltage event [8]
(2)
The corresponding COMTRADE generated by the virtual relays in both events are shown in Fig.7b for overcurrent and Fig.7b.The relative error in the overcurrent value and the overvoltage is calculated using the equation (2), which is lower than 3.6%. Results are shown in Table.II. B. Case 2: IEEE 13 nodes test feeder - recloser for overcur rent protection nodes N_671 and N_692
In this example, the IEEE 13 node test feeder shown in Fig.8 which is one of the default systems that DSSim-PC brings to the user is studied. This highly loaded 4.16 kV feeder is quite small and it has a recloser between nodes N_671 and N_692. Although the example is previously validated with load flow and short circuit according to the original test feeder.
A. Case 1: Basic example - overcurrent and overvoltage
M.in ""'
protection
Based on a simple case that was tested using two relays in a RT-Hll., testbed [8], an overvoltage and an overcurrent protection are implemented using now the virtual relay. There is a basic feeder and two branches each one with a certain load. Load LD_l is highly sensible to overvoltage phenomena. A three phase fault is programmed at the bus N_6 near to load LD_2, which is 4 times higher than LD_l. The first event is shown in Fig.6a, the overcurrent protection is tripped in one of the virtual relays (TCC=IEC extremely inverse C5). Up next, the action of that relay causes an overvoltage in the bus N_2 due the disconnection of load LD_l. This event is shown in Fig.6b
Fig. 8. IEEE 13 node test feeder and a 3 phase fault at bus N_692
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The idea is to reproduce a 3 phase fault and a single phase fault to ground in the bus N_692, therefore the user can see the operation of the virtual relay with this phenomena and obtain the COMTRADE file associated to these events. To do so, the original TCC curve is progranuned in the virtual relay. COMTRADE Files for both events are shown:
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in the three different failure scenarios show that the operation is consistent not only with the standard but also seems alike with the real-time COMTRADE results. Appendix A shows the COMTRADE results for faults F1 138000, F1 4160 and F2 4160 with the virtual relay, that seems to be highly consistent with the obtained results in [12]. Table II sununarizes the relative error for case A (Basic example: overcurrent and overvoltage) and case C (IEEE 2422001 with faults F1 138000, F1 4160 and F2 4160). Table II RELATIVE ERROR FOR CASES A AND C
'-
(a)
(b)
Fig, 9. COMTRADE results for (a) Three phase fault and (b) single phase fault bus N_692
COMTRADE Case A Overvoltage Overcurrent Case C Fl 138000 Fl 4160 F2 4160
And finally, for this case the reclosing sequence is activated and succesfully performed:
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Note that ANSI function was programmed to make a reclosing sequence with 2 trials. The first trip is detected and the breaker opens almost in 1 cycle. Approximately 60 ms after this trip, a reclosing trial is activated but the fault remains active. Finally after 140 ms The system reaches a complete reclosing operation. C. Case 3: Overcurrent protection coordination based on the
real-time hardware-in-the-loop study IEEE 242-2001
Since this particular and useful case was tested in real time [12] for understanding and training with protection co ordination in industrial systems, the implementation of the virtual relay allows to expand the benefits of the real-time test bed for protective relaying control. The advantage of this application contributes to a better interaction with the standard 242-2001 because the user can now implement each relay with a virtual environment, which means an important highlight to be include in academia (protection courses), professional training with real distribution systems models and future standardization. Using the model of IEEE 242-2001 in DSSim-PC, the results for faults F1 138000, F1 4160 and F2 4160 are tested using virtual relays. Relative error between the real time results and COMTRADE acquired by the virtual relay
Relative error Vp (%)
Relative error Ip(%)
3,571428571 3,278688525
1.41955836
5,287251087 0.301265823 0.301265823
0,819277108 0.448859455 1.43153527
-
V. CONCLUSION AND FURTHER WORK
This paper presented the first version of a virtual feeder protection relay. The operation of the proposed relay shows consistency with results previously tested on real-time studies. The Std C37.111 for COMTRADE and event recording was successfully integrated within the virtual relay so protective studies can be done using this first model and running distri bution systems in DSSim-PC. The validation of the virtual relay performance is assessed with voltage and current phenomena with 3 different case of study. The relative error between real-time hardware-in-the loop results and the virtual relay, is lower than 5.3%. Further work is expected with this application of new protective functions also for transmission systems and the future development of setting-less protection schemes. The virtual relay is versatile, scalable and flexible to design new protection algorithms. ApPENDIX A COMTRADE RECORDS FOR FAULTS F1 138000, F1 4160 AND F2 4160 IN THE CASE STD IEEE 242-2001 WITH ONLINE SIMULATION
VIRTUAL RELAY
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[l0] !. G. Kulis, A. Marusic, , and G. Leci, "Protection relay software models in interaction with power system simulators," in 2012 P roceedings of the 35 th International Convention MIPRO, Opatija, 2012. [ll] D. Celeita, S. Zambrano, and G. Ramos, "Fault location framework for distribution systems with DG using DSSim-PC," in 2014 1EEE P ES
-,�
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(PES T&D-LA). IEEE, Sept 10-13 2014, pp. 1-6. [12] D. Celeita, J. D. Pico, and G. Ramos, "Protection coordination analysis under a real-time architecture for industrial distribution systems based on the std ieee 242-2001," IEEE Transactions on Industry Applications, vol. PP, no. 99, p. 7, March 2016. [l3] IEEE Guide for Protective Relaying of Utility- Consumer Interconnec tions 1EEE Std 357-1973 (ANSI C37.95-1974), IEEE Std., May 24 1973. [14] IEEEIIEC Measuring relays and protection equipment Part 24: Common format for transient data exchange (COMTRADE) for power systems -
Fig. 12. Virtual relay COMTRADE record for Fl 4160
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Redline 1EEE Std C37.111-2013 (IEC 60255-24 Edition 2.0 2013-04) Redline, IEEE Std., April 30 2013. [l5] MiCOM P14x (P141, P142, P143 & P145 ) Feeder Management Relay PJ4x1EN M11h8, Technical manual ed., Schneider Electric, 2015. [l6] S. Electric. (2016) Network protection automation guide - npag. [Online]. Available: http://www2.schneider-electric.com/sites/corporate/ en/products-services/energy-distribution/automation/npag.page [17] W. group, "Comtrade: a new standard for common format for transient data exchange," IEEE Transactions on Power Delivery, vol. 7, no. 4, pp. 1920-1926, October 1992. [l8] D. Montenegro. (2013) DSSim-PC, Electrical Distribution System Simulator for Pc. Universidad de los Andes. [Online]. Available: https://sourceforge.neUprojects/dssimpc/ [l9] EPR!. (2013) OpenDSS. [Online]. Available: http://sourceforge.neU projects/electricdss/ [20] P. M. Anderson, Power system protection. [recurso electrnico J., ser. IEEE Press power engineering series. New York : McGraw-Hill : IEEE Press, cI999., 1999. [Online]. Available: http://ezproxy.uniandes.edu.co: 8080/1ogin ?url=http://search.ebscohost. comllogin. aspx ?direct=true&db= cat00683a&AN=udla.704538&lang=es&site=eds-live&scope=site [21] "Ieee standard common format for transient data exchange (comtrade) for power systems," IEEE Std C37.1l1-1999, pp. I-55, Oct 1999.
REFERENCES [I] EPRI, "Grid transformation workshop results: Advanced reading mate rial product id 1024659," Electric Power Research Institute EPRI, Tech. Rep., April 2012. [2] M. Kezunovic, A. Abur, L. Kojovic, V. Skendzic, H. Singh, C. W. Fromen, and D. R. Sevcik, "Dyna-test simulator for relay testing. i. design characteristics," IEEE Transactions on Power Delivery, vol. 6, no. 4, pp. pp. 1423-1429, October 1991. [3] IEEE Standard Common Format for Transient Data Exchange (COM TRADE) for Power Systems IEEE Std C37.111-1991, IEEE Std., 1991. [4] M. Kezunovic, J. Domaszewicz, V. Skendzic, M. Aganagic, J. K. Bladow, S. M. McKenna, and D. M. Hamai, "Design, implementation and validation of a real-time digital simulator for protection relay testing," IEEE Transactions on Power Delivery, vol. 11, no. I, pp. pp. 158-164, January 1996. [5] P. G. McLaren, K. Mustaphi, G. Benmouyal, S. Chano, A. Girgis, C. Henville, M. Kezunovic, L. Kojovic, R. Marttila, M. Meisinger, G. Michel, M. S. Sachdev, V. Skendzic, T. S. Sidhu, and D. Tziouvaras, "Software models for relays," IEEE Transactions on Power Delivery, vol. 16, no. 2, pp. pp. 238-245, April 2001. [6] A. P. S. Meliopoulos and G. 1. Cokkinides, "A virtual environment for protective relaying evaluation and testing," IEEE Transactions on Power Systems, vol. 19, no. I, pp. pp. 104-111, February 2004. [7] M. B. Miranda, "Virtual reality in the operation and protection relay in substations," in 10th lET International Conference on Developments in Power System Protection (DPSP 2010). Managing the Change, IET, Ed., Manchester, 2010. [8] D. Celeita, M. Hernandez, G. Ramos, N. Penafiel, M. Rangel, and J. D. Bernal, "Implementation of an educational real-time platform for relaying automation on smart grids," Electric Power Systems Research, vol. 130, pp. 156-166, 2016. [9] W. Guo-yang, S. Xin-li, T. Yong, Z. Wu-zhi, and L. Tao, "Modeling of protective relay systems for power system dynamic simulations," in 2011 IEEEIPES Power Systems Conference and Exposition (PSCE), Phoenix, 2011.
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