GRD Journals- Global Research and Development Journal for Engineering | Volume 1 | Issue 6 | May 2016 ISSN: 2455-5703
Implementation of Distance Relay for Standalone System Abhay Dalal Assistant Professor Department of Electrical Engineering RGCER, Nagpur Pranay Shete Assistant Professor Department of Electrical Engineering YCCE, Nagpur
Mnaish Kurwale Assistant Professor Department of Electrical Engineering RGCER, Nagpur
Parag Shewane Assistant Professor Department of Electrical Engineering DBACER, Nagpur
Pratik Bhele Assistant Professor Department of Electronics Engineering RGCER, Nagpur
Abstract Key role of this paper is to modulate and simulate distance relays using MATLAB. Relays are utilized to protect electric power systems against trouble and power blackouts as well as to regulate and control the generation and distribution of power. The primary function of the protective relay is to sense the fault in the system, is to protect standalone system from islanding, such that the trip coil of the circuit-breaker is energized and the faulty section of the system is disconnected from the rest of the system. Keywords- Fault, Distance relay, islanding, arc resistance, reach
I. INTRODUCTION In this paper the implementation of distance relay using MATLAB has been discuss to protract the standalone system whisch is shown in fig below Wind Generator DFIG
Load
Distribution System
Fig. 1: System Diagram
A. Impedance Relay In an impedance relay, the torque produced by a current element is balance against the torque of voltage element. The current element produces positive (pickup) torque. Whereas voltage element produces negative (reset) torque. In other words, an impedance relay is voltage restrained over current relay. It is used for medium transmission line. If | Zseen | < | Zset | then trip; else restrain X Line fault characteristics
B C
CR= Rarc= Arc reistance R
Trip
R
A
Restrain
Fig. 2: Characteristic of impedance relay
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
B. Reactance Relay A reactance relay is an over current relay with directional restraint. The directional element is arranged to develop maximum negative torque when its current lags its voltage by 90°. The induction-cup or double-induction-loop structures are best suited for actuating high-speed relays of this type. If |Xseen | < |Xset| then trip; else retrain
Fig. 3: Characteristics of reactance relay
C. Mho Relay The induction-cylinder or double-induction-loop structures are used in this type of relay. The complete distance relay for transmission-line protection is composed of three high speed mho units. A timing unit, connected in a manner similar to that shown for an impedance-type distance relay. Mho distance relays are used for long transmission lines. If |Zseen |< |Zn| cos (ɵ-λ) then trip ;else restrain.
X
B A
90°
Restrain
Zr Zn
OA=Zn
Trip
OB=Zr
R
O
Fig. 4: Characteristics of Mho relay
D. Comparison of the Impedance, Reactance, Mho Relay The comparison of different distance relays is given below
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
Table 4.1: Comparison impedance, mho, and reactance relay Sr .no
Features
1.
Characteristics
2.
Trip Law
Impedance relay
Reactance relay
Mho relay
If | Zseen | < | Zset |then trip ; else restrain Impedance relay is not inherently directional but can be made so by using directional unit with it. This delay automatically adjusts its operating time according to the distance of the relay from the fault point.
If |Xseen | < |Xn| then trip ; else restrain
If |Zseen|<|Zn| cos(ɵ-λ) then trip; else restrain.
Reactance relay on doesn't have directional feature nor can be made directional using directional unit.
Mho relay incorporates features of reactance relay with an addition that it is inherently directional
3.
Directional feature
4.
Fault behaviour
The relay operates for forward fault & restrains during reverse fault.
The relay operates for forward fault & restrains during reverse fault.
Operates for forward faults.
5.
Effect of Arc resistance
Least affected
No effect
Most affected
II. IMPLEMENTATION The different distance relays are implemented as follows. Start command give to the impedance relay it takes input as V, I, Zseen , Zset , Cos ɵ. Then according to trip law if Zseen < Zset then relay trips; or else it restrains after that stop the system.
Fig. 5: Flowchart for impedance relay
A. Flowchart of Reactance Relay Start command give to the reactance relay it takes input as V, I , Xseen , Xset . Then according to trip law; if Xseen < Xset then relay trips or else it restrains after that stop the system.
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
Fig. 6: Flowchart for reactance relay
B. Flowchart of Mho Relay Start command give to the mho relay it takes input as V, I, Zseen , Zset, ɵ,τ . Then according to trip law; if Zseen < Zset cos(ɵ-τ) then relay trips or else it restrains after that stop the system.
Fig. 7: Flowchart for mho relay
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
III. RESULTS The results for the simulation which was carried out on the above system are below
Fig 8: Simulation result of voltage for Distribution line during faulty condition
Above waveform shows sinusoidal voltage waveform but in the interval of 0.25 to 0.75 sec the voltage get reduces during faulty condition with magnitude of 22 KV for time interval of 0 to 0.25sec and for 0.75 to 1.
Fig. 9: simulation result of current for Distribution line during faulty condition
Above waveform shows sinusoidal current waveform but in the interval of 0.25 to 0.75 sec the current get increases drastically during faulty condition with magnitude of 4600 A. The fig 10 and fig 11 shows the simulation result of output voltage and current for impedance relay on Distribution line and effect of fault resistance on transmission line.
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
Fig. 10: simulation result of Voltage for Distribution line during faulty condition with distance relays
Fig. 11: Simulation result of current for distance relay on distribution line.
Above voltage and current waveform shows that after the interval of 0.25 sec the relay will trip for impedance relay on distribution line.
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Implementation of Distance Relay for Standalone System (GRDJE/ Volume 1 / Issue 6 / 007)
Fig. 12: Simulation result of voltage and current for effect of fault resistance on distribution line.
Above figure shows the voltage and current waveform after adding the arc resistance on transmission line the impedance relay will trip after the interval of 0.25.
IV. CONCLUSION It can be seen from the results all type of distance relays get operated for the fault, and for the fault having some arc resistance.
REFERENCES [1] [2] [3] [4] [5]
Muhd Hafizi Idrisa, Surya Hardia , Mohd Zamri Hasan, “Teaching Distance Relay Using MATLAB/Simulink Graphical User Interface 2013”.Malaysian Technical Universities Conference on Engineering & Technology 2012, MUCET 2012. Wu Guo-yang, Song Xin-li, Tang Yong, Zhong Wu-zhi, Liu Tao “Modeling of Protective Relay Systems for Power System Dynamic Simulations”, IEEE 2011. fIA HengXu’’, ZHANG BaoHui “Study on Reactance Relays for Single Phase to Earth Fault on EHV Transmission Lines”, 2004 International Conference of Power System Technology - POWERCON 2004 Singapore, 21-24 November 2004. Huanzhang Liu, Qiankuan Liu, Shaofeng Huang, and Qixun Yang “Phase-to-Phase Distance Relay Based on the Measured Impedance Trajectory”, IEEE 2007. Auday A.H. Mohamad Al-Mansour University College Baghdad, Iraq Essar Gafer Ahmed Electrical Engineering Khartoum, Sudan “MATLAB-Simulink SFunction forModeling Digital MHO Distance Relay” International Conference on Computing, Control, Networking, Electronics and Embedded Systems Engineering, 2015
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