Journal of Reliable Power - SEL

More documents

Recommendations

Info

13 XIII. CONCLUSIONS • Evolving faults can challenge fault location and targeting algorithms; offline tools can improve fault location accuracy. • Evolving faults can delay distance element tripping; common zone timing allows faster fault clearing. • Evolving faults can create reclosing problems; use trip elements to initiate reclosing and nonreclosing elements in drive-to-lockout logic. • Carrier holes cause DCB scheme problems; BT extension logic adds security. • Sensitivities of local and remote line relays should be matched. • Commissioning tests should concentrate on proving the overall protection system. • Unique event reports should be archived as COMTRADE files and used to test new schemes. • CVT transients can cause Zone 1 overreach; CVT transient detection logic adds security. • Extend reclosing open intervals beyond CVT transient response and set fault detectors above inrush on lines with tapped loads. • Older LOP logic relied on fault detectors set above normal load currents; improved LOP logic operates faster and is less dependent on fault detector settings for security. • Relays that include multiple polarization schemes and choose the appropriate element for the system and fault offer the best sensitivity and security. • Do not apply standard settings blindly; directional element performance is critical and should be checked, especially for extreme conditions. • Set carrier extension pickup delay to zero in DCB schemes. • Missing or multiple ground wires in instrument transformer circuits cause directional element misoperations; thorough commissioning tests and automated meter data comparisons should find these errors before misoperations occur. [4] G. Alexander, K. Zimmerman, and J. Mooney, “Setting the SEL-421 Relay With Sub-Cycle Elements in a Directional Comparison Blocking Scheme,” Schweitzer Engineering Laboratories, Inc. Application Guide 2007-10. [Online] Available: http://www.selinc.com/aglist.htm. [5] A. Guzman, J. Roberts, and K. Zimmerman, “Applying the SEL-321 Relay to Permissive Overreaching Transfer Trip (POTT) Schemes,” Schweitzer Engineering Laboratories, Inc. Application Guide 95-29. [Online] Available: http://www.selinc.com/aglist.htm. [6] J. Roberts, E. O. Schweitzer III, R. Arora, and E. Poggi, “Limits to the Sensitivity of Ground Directional and Distance Protection,” presented at the 1997 Spring Meeting of the Pennsylvania Electric Association Relay Committee. [Online] Available: http://www.selinc.com/techpprs.htm. [7] D. Hou and J. Roberts, “Capacitive Voltage Transformers: Transient Overreach Concerns and Solutions for Distance Relaying,” presented at the 22nd Annual Western Protective Relay Conference in Spokane, WA, October 1995. [Online] Available: http://www.selinc.com/techpprs.htm. [8] J. Mooney and S. Samineni, “Distance Relay Response to Transformer Energization: Problems and Solutions,” presented at the Texas A&M Conference for Protective Relay Engineers, College Station, TX, March 2007. [Online] Available: http://www.selinc.com/techpprs.htm. [9] SEL-321 Instruction Manual, Schweitzer Engineering Laboratories, Inc., Pullman, WA. [Online] Available: http://www.selinc.com/instruction_manual.htm. [10] SEL-221G5 Instruction Manual, Schweitzer Engineering Laboratories, Inc., Pullman, WA. [Online] Available: http://www.selinc.com/instruction_manual.htm. [11] J. Roberts and R. Folkers, “Improvements to the Loss-of-Potential (LOP) Function in the SEL-321,” Schweitzer Engineering Laboratories, Inc. Application Guide 2000-05. [Online] Available: http://www.selinc.com/aglist.htm. [12] K. Zimmerman, “Negative-Sequence Directional Element Revisited,” presented at the 21st Annual SEL Technical Seminar at the Western Protective Relay Conference in Spokane, WA, October 2005. [13] G. Alexander, K. Zimmerman, and J. Mooney, Schweitzer Engineering Laboratories, Inc. Application Guide 2007-10. [Online] Available: http://www.selinc.com/aglist.htm. XVI. BIOGRAPHY David Costello graduated from Texas A&M University in 1991 with a BSEE. He worked as a system protection engineer at Central Power and Light and Central and Southwest Services in Texas and Oklahoma. He has served on the System Protection Task Force for ERCOT. In 1996, David joined Schweitzer Engineering Laboratories, Inc., where he has served as a field application engineer and regional service manager. He presently holds the title of senior application engineer and works in Boerne, Texas. He is a senior member of IEEE, and a member of the planning committee for the Conference for Protective Relay Engineers at Texas A&M University. XIV. ACKNOWLEDGMENT The author gratefully acknowledges Normann Fischer, Karl Zimmerman, Bill Fleming, Joe Mooney, and Matt Leoni for their contributions to the original event analyses. XV. REFERENCES [1] SEL-311B Instruction Manual, Schweitzer Engineering Laboratories, Inc., Pullman, WA. [Online] Available: http://www.selinc.com/instruction_manual.htm. [2] K. Zimmerman and D. Costello, “Impedance-Based Fault Location Experience,” presented at the 31st Annual Western Protective Relay Conference in Spokane, WA, October 2004. [Online] Available: http://www.selinc.com/techpprs.htm. [3] SEL-311C Instruction Manual, Schweitzer Engineering Laboratories, Inc., Pullman, WA. [Online] Available: http://www.selinc.com/instruction_manual.htm. © 2007 Schweitzer Engineering Laboratories, Inc. All rights reserved. 20070913 • TP6280-01 64 | Journal of Reliable Power
1 Adaptive Phase and Ground Quadrilateral Distance Elements Fernando Calero, Armando Guzmán, and Gabriel Benmouyal, Schweitzer Engineering Laboratories, Inc. Abstract—Quadrilateral distance elements can provide significantly more fault resistance coverage than mho distance elements for short line applications. Quadrilateral phase and ground distance element characteristics result from the combination of several distance elements. Directional elements discriminate between forward and reverse faults, while reactance and resistance elements are fundamental to the proper performance of the quadrilateral characteristic. Load flow considerations determine the choice of the polarizing quantity for these elements. Reactance elements must accommodate load flow and adapt to it. Resistive blinders should detect as much fault resistance as possible without causing excessive overreach or underreach of the quadrilateral distance element. In this paper, we discuss an adaptive quadrilateral distance scheme that can detect greater fault resistance than a previous implementation. We also discuss application considerations for quadrilateral distance elements. Phase B are shown), the tower structure, the insulator chains, the ground wire, and the different impedances to the flow of fault current. These impedances are simplified to be resistive values only [4][5]. I. OVERVIEW Whereas the literature debates the differences and benefits of mho and quadrilateral ground distance elements [1], this paper describes the theory, application, and characteristics of a particular implementation of phase and ground quadrilateral distance elements. It is well accepted that a quadrilateral characteristic is beneficial when protecting short transmission lines [1][2]. It is also accepted that sensitive pilot protection schemes do not rely on distance elements only; these schemes also rely on ground directional overcurrent (67G), a unit that provides higher fault resistance (Rf) detecting capabilities than ground distance elements of any shape [3]. Generally, high Rf faults have been associated with singleline-to-ground faults (AG, BG, CG). For these faults, the associated Rf is considerable. On the other hand, phase faults are less susceptible to high Rf values. However, because short transmission lines are much more affected by high Rf values, the element with the most fault detecting capabilities should be used [1][2][3]. A. Fault Resistance Short circuits along the transmission line will have some degree of additional impedance. If this additional impedance is negligible, the line impedance is prevalent, and the apparent impedance measured will reflect it by reporting an impedance with the same angle as the line impedance. On the other hand, if this additional impedance is not negligible, the measured apparent impedance no longer appears at the line angle. Fig. 1 shows the different components of fault resistance for transmission line faults. Although extremely simplified, the figure shows the phase conductors (only Phase A and Fig. 1. Visualizing the Rf component The Rtower resistance is generally called the “footing resistance.” It is a critical parameter regarding the design and construction of transmission lines [6]. For an insulation flashover fault, the return path is through the tower itself. When a foreign object touches the conductors, the current distributes between adjacent towers but returns through the footing resistance. Ideally, the smaller the footing resistance, the better the transmission line ground fault detection performance will be. However, even though smaller values exist, practical values range from 5 to 20 ohms; and in rocky terrain, the resistance could be 100 ohms or more [1]. In Fig. 1, Raφg represents the arc resistance for an insulator flashover for a phase-to-ground fault. This is in the path of the ground fault flashover current Igffo. Raφφ is the arc resistance for a phase-to-phase fault. The arc resistance value is dependent on the arc length and the current flowing through the arc. A well-accepted formula is the one empirically derived by A. Van Warrington, expressed in (1). Other equations yield similar results [7]. In (1), the arc length is expressed in meters. Rarc length = 28688.5 Ω (1) I 1.4 The arc initially presents a few ohms of impedance. Over time, it could develop into 50 or more ohms [1]. Importantly, its value is dependent on the arc length and the current Adaptive Phase and Ground Quadrilateral Distance Elements | 65
Page 1 and 2:
$12.00 Journal of Reliable Power Vo
Page 3 and 4:
Journal of Reliable Power Volume 1
Page 5 and 6:
Capable of running protection calcu
Page 7 and 8:
Both P and Q are two-input phase an
Page 9 and 10:
TABLE 1: MHO ELEMENT POLARIZING CHO
Page 11 and 12:
For an Aφ-ground fault on the syst
Page 13 and 14:
The most onerous 3φ fault is one w
Page 15 and 16: If the angle is near +120°, then t
Page 17 and 18: Impedance-Based Fault Location Expe
Page 19 and 20: A. Simple Reactance Method From Fig
Page 21 and 22: Figure 9 shows a screen capture of
Page 23 and 24: The relay then performs “torque
Page 25 and 26: IX. LAB TEST SETUP Several line fau
Page 27 and 28: APPENDIX The following are the rela
Page 29 and 30: The following shows the analog math
Page 31 and 32: Digital Communications for Power Sy
Page 33 and 34: increasing security by a factor of
Page 35 and 36: The receiver amplifier is the major
Page 37 and 38: Noise from faults or other sources
Page 39 and 40: 80 60 40 20 R F 100 3 3 S 2 5 6 4 1
Page 41 and 42: 15. A POTT scheme implemented over
Page 43 and 44: Transmission Line Protection System
Page 45 and 46: One-Cycle Directional Element Figur
Page 47 and 48: element misoperation. Shunt reactor
Page 49 and 50: • SW2 is in Position 1 when there
Page 51 and 52: Complete reclosing relay supervisio
Page 53 and 54: IX. BIOGRAPHIES Armando Guzmán, P.
Page 55 and 56: 2 II. COMMON ZONE TIMING In June 20
Page 57 and 58: 4 ment 67N2 after a 1-cycle carrier
Page 59 and 60: 6 VI. ZONE 1 OVERREACH DUE TO CVT I
Page 61 and 62: 8 1_VA 1_VB 1_VC 2_VA 2_VB 2_VC 3_V
Page 63 and 64: 10 The phasors during the fault are
Page 65: 12 The prefault data from the backu
Page 69 and 70: 3 C. Short Line Applications A shor
Page 71 and 72: 5 II. QUADRILATERAL DISTANCE ELEMEN
Page 73 and 74: 7 For the purpose of implementing t
Page 75 and 76: 9 The three-phase fault detection e
Page 77 and 78: 11 Zone 1 distance elements should
Page 79 and 80: 13 Fig. 24 shows the apparent resis
Page 81 and 82: 15 B. Adaptive Resistance Element F
Page 83 and 84: 17 Fig. 34 and Fig. 35 illustrate t
Page 85 and 86: Line Protection Bibliography Issue
Page 87 and 88: Hou, Daqing, and Jeff Roberts. “C
Page 90: ©2010 Schweitzer Engineering Labor
show all

Journal of Reliable Power - SEL

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?