Phase Rolling and the Impacts on Protection. By: Denglin (Dennis) Tang, Burns & McDonnell 2016 Minnesota Power Systems Conference

Transcription

1 Phase Rolling and the Impacts on Protection By: Denglin (Dennis) Tang, Burns & McDonnell 2016 Minnesota Power Systems Conference

2 Overview Background Introduction. Relays Settings and Operation. Phase Rolling Characteristics. Solving the Currents for Phase Rolling. Sample calculation. Further Discussion.

3 Introduction S4 S3 S2 Relay operated Phase rolling R43 R32 R21 x S5 S1 R54 R12 Relay operated Relay operated

4 Questions Why did the under-reaching zone 1 distance element which is several buses away operate? Is there any way to prevent such situation beforehand?

5 Relay Settings and the Measurements 85% reaching All Data in Primary Side

6 Relay Operation X(Ω ) Protected Line Apparent Impedance Zone 1 MHO Circle R(Ω )

7 Measures to Prevent Phase Rolling Phasing verification during commissioning time. v Simple and easy v Has been applied so far Special synchronizing scheme to prevent phase rolling closing. v Traditional synchronizing scheme doesn t solve the issue v Special scheme is possible to be developed Treatment of distance elements is challenging. v Could be complicate and challenging v Not recommended now that there are easy and simple solutions.

8 Special Synchronizing Scheme C B B o A C o A Traditional phase synchronizing. v Phase A synchronized v Still possible to close with phase rolling C C Special synchronizing scheme. o A o A v Need to have 2 phases synchronized B B

9 Special Synchronizing Scheme (Cont d) V 1 (ØA) V Ref (ØA) V 2 (ØA) Typical 2 breaker synchronizing. Magnitude Factor 1: 1.0 Angle shift 1: 0.0 Magnitude Factor 2: 1.0 Angle shift 2: 0.0 v Phase A synchronized v Still possible to close with phase rolling V 1 (ØA) V Ref (ØA) V 2 (ØB) Magnitude Factor 1: 1.0 Angle shift 1: 0.0 Magnitude Factor 2: 1.0 Angle shift 2: Special synchronizing scheme. v Need to have 2 phases synchronized v Both V1 and V2 synchronized to close Depending on the phase rotation ABC or ACB, angle shift could be either 120 or -120

10 Phase Rolling Characteristics Rare Phenomenon Regular Software Tool not Applicable No Specific Location Apparent Impedance Relay Fault Location Relay System Configuration E SA E RA E SB E RB E SC E RC

11 Analysis Method Compare Regular Software Tool Short Circuit Analysis Electric Circuits KCL, KVL, Ohms Law, etc. Symmetrical Component Phase Rolling Analysis Electric Circuits KCL, KVL, Ohms Law, etc.

12 Solving the Phase Rolling I A1 Z TS I A1 E SA Z SS I A1+I A2 I A2 ZLS I A2 I A1+I A2 Z RS E RA Z TM Z SM I B1 Z TS Z LM I B1 Z RM E SB Z SS I B1+I B2 I B2 Z LS I C2 I B1+I C2 Z RS E RB E SC Z SS Z SM I C1+I C2 I C2 Z LS Z LM Z TM I B2 I C1+I B2 Z RM Z RS E RC I C1 Phase Rolling Z TS I C1 (Mutual are shown for phase A-B & B-C only for simplicity

13 System Data (Impedances) Preparation System Equivalence (By Regular Software Tools) Sequence to Phase

14 Polynomials Z SS *(I A1 +I A2 ) + Z SM *(I B1 +I B2 +I C1 +I C2 ) + Z TS *I A1 + Z TM *(I B1 +I C1 ) + Z RS *(I A1 +I A2 ) + Z RM *(I B1 +I B2 +I C1 +I C2 ) = E SA -E RA Z SS *(I A1 +I A2 ) + Z SM *(I B1 +I B2 +I C1 +I C2 ) + Z LS *I A2 + Z LM *(I B2 +I C2 ) + Z RS *(I A1 +I A2 ) + Z RM *(I B1 +I B2 +I C1 +I C2 ) = E SA -E RA Z SS *(I B1 +I B2 ) + Z SM *(I A1 +I A2 +I C1 +I C2 ) + Z TS *I B1 + Z TM *(I A1 +I C1 ) + Z RS *(I B1 +I C2 ) + Z RM *(I A1 +I A2 +I C1 +I B2 ) = E SB -E RB Z SS *(I B1 +I B2 ) + Z SM *(I A1 +I A2 +I C1 +I C2 ) + Z LS *I B2 + Z LM *(I A2 +I C2 ) + Z RS *(I C1 +I B2 ) + Z RM *(I A1 +I A2 +I B1 +I C2 ) = E SB -E RC Z SS *(I C1 +I C2 ) + Z SM *(I A1 +I A2 +I B1 +I B2 ) + Z LS *I C2 + Z LM *(I A2 +I B2 ) + Z RS *(I B1 +I C2 ) + Z RM *(I A1 +I A2 +I C1 +I B2 ) = E SC -E RB Z SS *(I C1 +I C2 ) + Z SM *(I A1 +I A2 +I B1 +I B2 ) + Z TS *I C1 + Z TM *(I A1 +I B1 ) + Z RS *(I C1 +I B2 ) + Z RM *(I A1 +I A2 +I B1 +I C2 ) = E SC -E RC Re-arrange (Z SS +Z TS +Z RS )*I A1 + (Z SS +Z RS )*I A2 + (Z SM +Z TM +Z RM )*I B1 + (Z SM +Z RM )*I B2 + (Z SM +Z TM +Z RM )*I C1 + (Z SM +Z RM )*I C2 = E SA -E RA (Z SS +Z RS )*I A1 + (Z SS +Z LS +Z RS )*I A2 + (Z SM +Z RM )*I B1 + (Z SM +Z LM +Z RM )*I B2 + (Z SM +Z RM )*I C1 + (Z SM +Z LM +Z RM )*I C2 = E SA -E RA (Z SM +Z TM +Z RM )*I A1 + (Z SM +Z RM )*I A2 + (Z SS +Z TS +Z RS )*I B1 + (Z SS +Z RM )*I B2 + (Z SM +Z TM +Z RM )*I C1 + (Z SM +Z RS )*I C2 = E SB -E RB (Z SM +Z RM )*I A1 + (Z SM +Z LM +Z RM )*I A2 + (Z SS +Z RM )*I B1 + (Z SS +Z LS +Z RS )*I B2 + (Z SM +Z RS )*I C1 + (Z SM +Z LM +Z RM )*I C2 = E SB -E RC (Z SM +Z RM )*I A1 + (Z SM +Z LM +Z RM )*I A2 + (Z SM +Z RS )*I B1 + (Z SM +Z LM +Z RM )*I B2 + (Z SS +Z RM )*I C1 + (Z SS +Z LS +Z RS )*I C2 = E SC -E RB (Z SM +Z TM +Z RM )*I A1 + (Z SM +Z RM )*I A2 + (Z SM +Z TM +Z RM )*I B1 + (Z SM +Z RS )*I B2 + (Z SS +Z TS +Z RS )*I C1 + (Z SS +Z RM )*I C2 = E SC -E RC

15 Sample Calculation E SA = 1.025*138kV/ 3 0 E SB = 1.025*138kV/ E SC = 1.025*138kV/ E RA = 1.025*138kV/ 3 0 E RB = 1.025*138kV/ E RC = 1.025*138kV/ Z SS = 25.15Ω 86.04, Z SM = 4.62Ω Z RS = 1.91Ω 85.96, Z RM = 0.12Ω Z LS = 3.05Ω 77.79, Z LM = 1.37Ω Z TS = 25.47Ω 74.69, Z TM = 12.57Ω 68.25

16 Sample Calculation (Cont d) Calculation in Mathcad

17 Compare: Analysis vs. Measurements Calculation Results Complex-Phasor Conversion Phase B i Phase C i Measured (A) Calculated (A) Error Error% Phase B Phase C Phasor Shift

18 Further Discussion In case of cross feeding, current distribution may necessary. E FA E SA E RA E FB E SB E RB E FC E SC E RC

19 Further Discussion (Cont d) What matters: Security Vs. Dependability v In case of phase rolling, the relays need to isolate the phase rolling line as soon as possible v The apparent impedance need to be able to operate the zone 1 or zone 2 distance element of the phase rolling line

20 Conclusion Phase rolling is a rare phenomenon. Phasing verification or special synchronizing scheme could be used to prevent from the phase rolling. Phase rolling currents/voltages could be solved electric circuits fundamental knowledges. Apparent impedances could be calculated to verify the possible mis-operation of the non-phase rolling lines or to confirm the relays of the phase rolling lines will operate to isolate.

21 Questions