Analysis of distance protection relay in presence of static synchronous compensator statcom
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This document analyzes the impact of a Static Synchronous Compensator (STATCOM) on distance protection relays for transmission lines. It presents a simulation of a 400kV, 300km transmission line with a 100MVA STATCOM at the midpoint and distance relays at each end. The simulation shows that the STATCOM affects the impedance seen by the relays during faults, as it injects current and alters line parameters. Traditional relay settings based solely on line impedance may not operate correctly with a STATCOM present. The document discusses modeling of the transmission line, STATCOM, and distance relays in MATLAB/Simulink to study their performance under normal and fault conditions with the STATCOM.
![International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME
15
Finding suitable right ways is particularly difficult in the developing countries and gaining
the necessary approvals is more time consuming than ever. Due to these situations, operators are
looking for ways to utilize these existing power lines more effectively. Flexible alternating current
transmission system (FACTS) have all these capability to meet the challenges presented by the fast
growing power system. The term FACTS covers all modern power electronics based system used in
ac power transmission system.
Following are the benefits of using FACTS devices in transmission line.
i) Steady state transmittable power can be improved.
ii) Voltage profile can be improved.
iii) Better utilization of existing transmission lines.
iv) System Power factor has been improved.
However, the employing of FACTS devices like static synchronous compensator
(STATCOM) in transmission lines have a profound impact on the operation of other equipment in
the system especially the protection relay [1].
Particularly the transients superimposed on power frequency voltage and current waveforms
will be affected in both steady state and transient state, particularly during fault conditions can be
significantly different from those of system without STATCOM in which many system parameters
are different like line impedance and power angle. And this will affect the conventional protection
system based on Impedance relay [2].
Literature review indicate that FACTS device introduce new power system dynamics that
must analyzed. These are summarized as:
i) The rapid changes in system parameters such as line impedance, power angle and line currents.
ii) The harmonics establish into the adjacent ac power system.
iii)Transients introduced into the system due to center action.
Thus it’s very important to study the effects of FACTS devices such as STATCOM on
protection relay scheme for transmission line [1] - [3].
STATCOM is belonging to FACTS family and most popular in midpoint compensation technique.
It depends on voltage source converter (VSC) techniques and can inject an almost sinusoidal
current with variable magnitude and almost in quadrature with the connecting line voltage of the bus
[4]-[5].
Mid –Point compensation technique is widely used, in mid –point compensation technique
transmission line get separated into two equal parts with equal impedance division of transmission
line. first segment can deliver power from sending end to mid –point with equivalent impedance of
line is Z/2 and second segment from mid-point to receiving end with an equal impedance of Z/2
respectively [4].
The study in [2] and [7] show that the presence of FACTS device and its location had great
impact on impedance relay. Particularly when FACTS device is in fault loop, its voltage and current
injection will affect both steady and transient components in voltage and current and hence the
apparent impedance seen by a conventional distance relay is different from that of a system without
FACTS device.
In this paper, analysis of distance relay in presence of STATCOM on transmission line and
investigate the impact of STATCOM on distance relay in normal and abnormal condition are
studied. Detail model of transmission line having 400KV, 300Km with distance relay and
STATCOM is proposed.
II. DISTANCE RELAY
One of the most important equipment employed in the protection of power system are
protection relay. These are one of the most flexible, economic and well known device that provide](https://image.slidesharecdn.com/analysisofdistanceprotectionrelayinpresenceofstaticsynchronouscompensatorstatcom-150820093919-lva1-app6892/85/Analysis-of-distance-protection-relay-in-presence-of-static-synchronous-compensator-statcom-2-320.jpg)
![International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME
16
reliable, fast and inexpensive protection. Distance relay have been using successfully from many
years and most popular type of protection for transmission lines. Distance relay operation based on
the measurement of impedance at the relay point to fault point and compare it with predefine set
value. In conventional protection scheme measure impedance by a distance relay depends only on
the length of the line section located between the fault and the relaying located point. But in case of
FACTS employing transmission line protection scheme impedance depend on FACTS operation
during fault condition [6].
Consider the proposed distance protection scheme shown in fig.1. The apparent impedance
calculation is based on symmetrical components transformation technique using power frequency
components of voltage and current signal measured at relay point.
A transmission line with three zones protection scheme is considered. In which reach setting
of zone one is up to 80% of the protected line impedance for instantaneous zone one protection. For
zone second it should be 120% and for zone third it should be 140-150% of the protected line
impedance. Fig.2 shows typical three zone Mho type distance protection scheme.
Fig. 1. Proposed distance protection scheme with STATCOM at midpoint compensation.
Fig.2 Typical three zone distance protection scheme](https://image.slidesharecdn.com/analysisofdistanceprotectionrelayinpresenceofstaticsynchronouscompensatorstatcom-150820093919-lva1-app6892/85/Analysis-of-distance-protection-relay-in-presence-of-static-synchronous-compensator-statcom-3-320.jpg)
Analysis of distance protection relay in presence of static synchronous compensator statcom
- 1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 14 ANALYSIS OF DISTANCE PROTECTION RELAY IN PRESENCE OF STATIC SYNCHRONOUS COMPENSATOR (STATCOM) G.R.Barse1 , A.A. Bhole 2 1,2 Department of Electrical Engineering, Government College of Engineering Aurangabad, India ABSTRACT Distance relay is most popular in protection of High Voltage and extra high voltage transmission lines science many decades. In this paper analysis of distance protection relay employing with STATCOM on transmission line is done by using the simulation. Also effect of static synchronous compensator (STATCOM) on the distance protection relay under normal and abnormal conditions is investigated. However traditional updating of transmission lines is difficult. To fulfill power demand on the system need to utilize existing power system with the help of flexible alternating current transmission system (FACTS), but this will affect the traditional protection scheme for transmission lines. Simulation result clearly shows the impact of STATCOM on distance protection scheme during fault conditions. A typical 400KV, 300KM long transmission line with 100MVA STATCOM in MATLAB/Simulink is studied. Keywords: Distance Relay, Power System Prtoction, STATCOM, Modeling, Faults, MATLAB/ Simulink. I. INTRODUCTION Modern power system are designed to operate effectively to supply power from utility to distribution centers with very high reliability and optimum cost. Demand for electrical energy continuously growing steadily, especially in developing countries like India where growth of industrialization rapidly increasing. To fulfill these new power demand on power system, need to develop new infrastructure but constructing new transmission lines is very difficult due to economic and environmental limitations. INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY (IJEET) ISSN 0976 – 6545(Print) ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME: www.iaeme.com/IJEET.asp Journal Impact Factor (2015): 7.7385 (Calculated by GISI) www.jifactor.com IJEET © I A E M E
- 2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 15 Finding suitable right ways is particularly difficult in the developing countries and gaining the necessary approvals is more time consuming than ever. Due to these situations, operators are looking for ways to utilize these existing power lines more effectively. Flexible alternating current transmission system (FACTS) have all these capability to meet the challenges presented by the fast growing power system. The term FACTS covers all modern power electronics based system used in ac power transmission system. Following are the benefits of using FACTS devices in transmission line. i) Steady state transmittable power can be improved. ii) Voltage profile can be improved. iii) Better utilization of existing transmission lines. iv) System Power factor has been improved. However, the employing of FACTS devices like static synchronous compensator (STATCOM) in transmission lines have a profound impact on the operation of other equipment in the system especially the protection relay [1]. Particularly the transients superimposed on power frequency voltage and current waveforms will be affected in both steady state and transient state, particularly during fault conditions can be significantly different from those of system without STATCOM in which many system parameters are different like line impedance and power angle. And this will affect the conventional protection system based on Impedance relay [2]. Literature review indicate that FACTS device introduce new power system dynamics that must analyzed. These are summarized as: i) The rapid changes in system parameters such as line impedance, power angle and line currents. ii) The harmonics establish into the adjacent ac power system. iii)Transients introduced into the system due to center action. Thus it’s very important to study the effects of FACTS devices such as STATCOM on protection relay scheme for transmission line [1] - [3]. STATCOM is belonging to FACTS family and most popular in midpoint compensation technique. It depends on voltage source converter (VSC) techniques and can inject an almost sinusoidal current with variable magnitude and almost in quadrature with the connecting line voltage of the bus [4]-[5]. Mid –Point compensation technique is widely used, in mid –point compensation technique transmission line get separated into two equal parts with equal impedance division of transmission line. first segment can deliver power from sending end to mid –point with equivalent impedance of line is Z/2 and second segment from mid-point to receiving end with an equal impedance of Z/2 respectively [4]. The study in [2] and [7] show that the presence of FACTS device and its location had great impact on impedance relay. Particularly when FACTS device is in fault loop, its voltage and current injection will affect both steady and transient components in voltage and current and hence the apparent impedance seen by a conventional distance relay is different from that of a system without FACTS device. In this paper, analysis of distance relay in presence of STATCOM on transmission line and investigate the impact of STATCOM on distance relay in normal and abnormal condition are studied. Detail model of transmission line having 400KV, 300Km with distance relay and STATCOM is proposed. II. DISTANCE RELAY One of the most important equipment employed in the protection of power system are protection relay. These are one of the most flexible, economic and well known device that provide
- 3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 16 reliable, fast and inexpensive protection. Distance relay have been using successfully from many years and most popular type of protection for transmission lines. Distance relay operation based on the measurement of impedance at the relay point to fault point and compare it with predefine set value. In conventional protection scheme measure impedance by a distance relay depends only on the length of the line section located between the fault and the relaying located point. But in case of FACTS employing transmission line protection scheme impedance depend on FACTS operation during fault condition [6]. Consider the proposed distance protection scheme shown in fig.1. The apparent impedance calculation is based on symmetrical components transformation technique using power frequency components of voltage and current signal measured at relay point. A transmission line with three zones protection scheme is considered. In which reach setting of zone one is up to 80% of the protected line impedance for instantaneous zone one protection. For zone second it should be 120% and for zone third it should be 140-150% of the protected line impedance. Fig.2 shows typical three zone Mho type distance protection scheme. Fig. 1. Proposed distance protection scheme with STATCOM at midpoint compensation. Fig.2 Typical three zone distance protection scheme
- 4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 17 III. SIMULATION SCHEME A) Simulation scheme for distance Protection relay Distance relay can be design using simpower system design tool in Matlab Simulink which is shown in fig. 3. Following steps are required for distance relay modeling in simulation work space. 1. Input signal: current and voltage waveforms are captured from the instrument transformers and scale down to desire level for further processes. 2. Filtering Block: By using low pass filter remove the noise and undesired components of frequencies from the input signals. 3. Quantizer: This block convert input sinusoidal signal into stair step form, so that many closed points on the input signal are mapped on one point on the output axis. It represent as y = q*round (u/q). Where q is quantization interval and u is input. 4. Digital Filtering: second order finite impulse responses type digital filter block preferred for distance relay modeling. Main role of this block is to convert analog signal to discrete signal. 5. Discrete Fourier: DFT is ideal method of detecting the fundamental frequency components in fault signal. It compute the magnitude and phase at discrete frequencies at discrete time intervals. 6. Algorithm: Algorithm part required for decision of trip command for final output. Fig.3. Block diagram of distance relay model B) Simulation scheme for STATCOM: Fig.4 show the STATCOM and its controller. Voltage source converter, PWM generator and PI controller, are the main parts of STATCOM. 1. Voltage source converter (VSC): Main part of the STATCOM is voltage source converter in which bridge of IGBTs are used for converter. In VSC at dc side dc capacitor banks utilize as a dc energy source. 2. PWM generator: PWM generator used for generation of gate pulse for IGBTs Bridge. In this technique sinusoidal sine wave is compared with carrier triangular wave. By varying the modulation index, converter output is vary. 3. PI controller: Error signal from input and VSC output given to the PI controller which can control the modulation index.
- 5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 18 Fig.4. STATCOM with its controller. IV. SIMULATION RESULT To demonstrate the impact of STATCOM on the distance protection relay Matlab Simulink model of 400KV, 300KM transmission model with 100MVA STATCOM and distance relay has been developed. A single phase to ground fault is considered in zone 1, zone 2 and zone 3 respectively. Also simulation result in the form of apparent impedance trajectory by the distance relay are shown in fig. 6(a -b) -fig.8 (a-b) and fig. 5 shows proposed simulation scheme. Fig.5. Proposed simulation scheme
- 6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. A. Without STATCOM Fig.6. Apparent impedance seen by relay during SLG fault A. Without STATCOM Fig.7. Apparent impedance seen by rel A. Without STATCOM Fig. 8. Apparent impedance seen by relay during SLG fault International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 19 . Without STATCOM B. With STATCOM Apparent impedance seen by relay during SLG fault in zone . Without STATCOM B. With STATCOM Apparent impedance seen by relay during SLG fault in zone 2. . Without STATCOM B. With STATCOM Apparent impedance seen by relay during SLG fault in zone 3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), © IAEME zone 1. ay during SLG fault in zone 2. in zone 3.
- 7. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 6, Issue 5, May (2015), pp. 14-20 © IAEME 20 V. CONCLUSION In this paper, the impact of STATCOM on a transmission line distance protection relay under the single phase to ground fault condition is investigated by MATLAB/Simulink. Fig.6– fig.8 shows the impedance trajectory of distance relay during fault, with and without STATCOM conditions. It clearly show the overreaching phenomenon on distance relay due to STATCOM installed on line. Its voltage and current injection will affect both steady and transient components in voltage and current and hence the apparent impedance seen by a conventional distance relay is different from that of a system without STATCOM device, which affect the traditional protection scheme of a transmission line. VI. REFERENCES 1. M. Khederzadeh, "The impact of FACTS device on digital multifunctional protective relays," in Proc. IEEE/PE Transmission and Distribution Conf. and Exhib. 2002: Asia Pacific, vol. 3, Oct. 6–10, 2002, pp. 2043–2048. 2. K. El-Arroudi, G. Joos, D.T. McGillis, “Operation of Impedance protection relays with the STATCOM,” Power Delivery, IEEE Transactions on Power Delivery, Volume: 17, Issue: 2, April 2002 Pages: 381-387. 3. A. Salemnia, M. Khederzadeh, and A. Ghorbani, “Impact of Static Synchronous Compensator (STATCOM) on Performance of Distance Relay”. European trans. on Elect power, vol.21, pp-2079, 2011. 4. N.G.Hingorani and L.Gyugyi, “Understanding FACTS Concepts and Technology of Flexible AC Transmission Systems”, IEEE Press, 2000 5. X.Y Zhou, H.F Wang, R.K Aggarwal, Beaumont, “THE IMPACT OF STATCOM ON DISTANCE RELAY”, 15th PSCC, Liege, 22-26 August 2005. 6. A. Kazemi, S. Jamali, and H. Shateri, “Impact of STATCOM modeling on its Effect of on Distance Relay Tripping Characteristic” 2008 IEEE, 978-1 4244-1718-6/08 7. D. Hemasundar Mohan Thakre V.S.Kale “Impact of STATCOM on Distance Relay – Modeling and Simulation Using PSCAD/EMTDC” 2014 IEEE Students’ Conference on Electrical, Electronics and Computer Science sr.no.978-1-4799-2526-1/14. 8. Dr Naarisetti Srinivasa Rao and Dasam Srinivas, “An Experimental Design To Improve Power Quality on STATCOM” International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 5, 2012, pp. 96 - 103, ISSN Print: 0976-6545, ISSN Online: 0976- 6553. 9. K M Mamatha Nalini.S, “STATCOM Based Power Quality Improvement in Grid Connected Renewable Energy Systems” International Journal of Electrical Engineering & Technology (IJEET), Volume 5, Issue 3, 2014, pp. 34 - 42, ISSN Print: 0976-6545, ISSN Online: 0976- 6553. 10. S.Munisekhar, O.Hemakesavulu and Dr.M.Padmalalitha, “Wind Energy Conversion Systems Using Fuzzy Controlled STATCOM For Power Quality Improvement” International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 4, 2013, pp. 108 - 117, ISSN Print: 0976-6545, ISSN Online: 0976-6553.