Journal of Reliable Power - SEL

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14 Following is a conservative approach to set Zone 2 that guarantees that the overreaching element sees all faults with specific Rf coverage. Fig. 27 shows the apparent resistance for a homogeneous system and no-load conditions. Fig. 28 shows Rset_zone2_pu for θL1 equal to 40, 55, 70, and 85 degrees and for θε equal to –2 degrees. Resistive Reach Setting Rset Zone 2 (pu) 15 10 5 40 55 70 85 Fig. 27. Apparent impedance for an end-of-line fault considering measurement errors From Fig. 27, we can estimate the required resistive reach Rset_zone2 and impedance reach Zset_zone2 settings according to (33) and (34) for a desired Rf coverage. ( θL1 + θε ) ( θL1) sin ( θε ) sin( θL1 + θε ) sin − j⋅θε Rset _ zone2 = • Real(KR) • Rf • e (33) sin Zset _ zone2 = ZL1 − • R set _ zone2 (34) We can represent Rset_zone2_pu as a function of Ppu according to (35). These values are the normalized values of Rset_zone2 and P (see Fig. 27) with respect to |ZL1|. ( θL1 + θε ) sin ( θε ) sin Rset _ zone2 _ pu = − • Ppu (35) 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 P (pu) Fig. 28. The resistive reach setting as a function of the impedance reach setting for several values of θL1 For the relay in Fig. 4, we calculate Rset_zone2 for a desired Rf equal to 3 ohms secondary. Using (33) with θε equal to –2 degrees and a fault at the end of the line, we obtain Rset_zone2 equal to 28.69 ohms secondary and Rset_zone2_pu equal to 14.35 pu. From Fig. 28, we obtain the required value of Ppu and the Zone 2 impedance reach Zset_zone2_pu equal to 1.5 or 150 percent of |ZL1|. V. DISTANCE ELEMENT PERFORMANCE A. Traditional Distance Element Characteristics Adaptive quadrilateral phase and ground distance elements were designed to improve Rf coverage in short line applications. A previous distance relay included a ground quadrilateral distance element characteristic with an adaptive reactance element and two resistance elements that calculate Rf according to (36) and a ground mho distance characteristic with an adaptive mho element that calculates the distance to the fault according to (37) [12] j⋅θ L1 ( ) * Im ⎡ V • I • e ⎤ ⎢ ⎥ R relay1 = ⎣ ⎦ ⎡ 3 Im ⎢ • I2 I0 • I e ⎣ 2 j⋅θ L1 ( + ) ( ⋅ ) ( ) * Re ⎡V • V1_ mem ⎤ m relay1 = ⎣ ⎦ j L1 Re ⎡ ⋅θ I • e • V1_ mem ⎣ ( ) * * ⎤ ⎥ ⎦ ⎤ ⎦ (36) (37) 78 | Journal of Reliable Power
15 B. Adaptive Resistance Element Fig. 29 shows the quadrilateral distance element characteristic that uses the adaptive reactance element of the previous design with an adaptive resistive element. X Adaptive Reactance Element setting of 11.52 ohms and an impedance reach (Zset) setting of 120 percent of ZL1. The mho distance element has a reach of 120 percent of ZL1. The sensitivity of all the distance elements is 0.05 • Inom. Fig. 30, Fig. 31, and Fig. 32 show the Rf coverage of mho and quadrilateral distance elements. We observe that the Rf coverage is severely reduced as the fault approaches the end of the line. As expected, the mho element is the one with less Rf coverage, and the adaptive resistance element has the greatest Rf coverage, especially for power flow in the forward direction, δ equal to 10 degrees. 20 18 Mho Distance Element Quadrilateral Distance Element Adaptive Resistive Element Z LINE Adaptive Resistive Element 16 14 Rset = 11.52 ohms δ = -10 degrees R Fault Resistance (ohms) 12 10 8 6 Fig. 29. Quadrilateral distance element characteristic with adaptive resistance element The adaptive resistive element calculates Rf according to (38) and (39), and compares the minimum of the two calculation results against the resistive setting. j⋅θ L1 ( ) j⋅θ L1 * ( ) Im ⎡ V • I2 • e ⎢ R2 = ⎣ Im ⎡ I • I2 • e ⎢⎣ Im ⎡ V • I ⎢ Rα = ⎣ Im ⎡ I • I ⎢⎣ ⎤ ⎥⎦ ⎤ ⎥⎦ * j⋅θ L1 ( α • e ) j⋅θ L1 * ( α • e ) ⎤ ⎥⎦ ⎤ ⎥⎦ * (38) (39) Equation (38) is equivalent to (11) and (12). It uses a different form of phase comparator equation. Equation (39) uses the alpha component (Iα = I1 + I2). C. Resistive Coverage To compare the resistive coverage of the traditional distance elements with the adaptive resistive element, we use the system in Fig. 4 and perform the tests discussed in the following sections. 1) Faults at Multiple Locations We calculate the maximum Rf that the distance elements can detect for an A-phase-to-ground fault for m values from 0 to 1 and load angles of δ equal to –10, 0, and 10 degrees. The quadrilateral distance elements have a resistive reach (Rset) 4 2 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fault Location (pu) Fig. 30. Rf coverage of mho and quadrilateral distance elements for δ equal to –10 degrees Fault Resistance (ohms) 8 7 6 5 4 3 2 1 Mho Distance Element Quadrilateral Distance Element Adaptive Resistive Element Rset = 11.52 ohms δ = 0 degrees 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Fault Location (pu) Fig. 31. Rf coverage of mho and quadrilateral distance elements for δ equal to 0 degrees Adaptive Phase and Ground Quadrilateral Distance Elements | 79
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$12.00 Journal of Reliable Power Vo
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Journal of Reliable Power Volume 1
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Capable of running protection calcu
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Both P and Q are two-input phase an
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TABLE 1: MHO ELEMENT POLARIZING CHO
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For an Aφ-ground fault on the syst
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The most onerous 3φ fault is one w
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If the angle is near +120°, then t
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Impedance-Based Fault Location Expe
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A. Simple Reactance Method From Fig
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Figure 9 shows a screen capture of
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The relay then performs “torque
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IX. LAB TEST SETUP Several line fau
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APPENDIX The following are the rela
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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 and 66: 12 The prefault data from the backu
Page 67 and 68: 1 Adaptive Phase and Ground Quadril
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Page 85 and 86: Line Protection Bibliography Issue
Page 87 and 88: Hou, Daqing, and Jeff Roberts. “C
Page 90: ©2010 Schweitzer Engineering Labor
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