PSCAD與電弧相關的模型

1、Shan JiangManitoba HVDC Research CentreWinnipeg, Manitoba，CanadasupportPSCAD與電弧相關的模型及示例斷路器合閘“statistical breaker close” 元件斷路器分閘“breaker arc”元件“reignition”元件 Restrike 重擊穿故障電弧“fault arc”元件電弧爐(EAF)“EAF”元件Page 2斷路器合閘特點斷路器可以在基頻周波的任意一點合閘暫態(tài)因合閘點不同而異(Point On Wave - POW)每相的合閘時間符合正態(tài)分布(normal distributed)Page

2、3斷路器合閘Pre-insertioncontactresistorMain contactPage 4TbTb+DtaTb+DtmDtaDtmclose requestclose pre-insertion contactsclose main contactsT(sec)TaTm斷路器合閘注: 每相的合閘時間符合正態(tài)分布Page 5Page 6Statistical breaker close均數(shù) =2標準差 =1，對應出現(xiàn)概率 68.2%標準差 =2，對應出現(xiàn)概率 95.4%標準差 =3，對應出現(xiàn)概率 99.7%標準差 =4，對應出現(xiàn)概率 99.999%Page 7Statistical

3、 breaker closeIf cls = 0.9, the closing time of the three phases will lie in area: (cls+0.1, cls+2.1) = (1, 3)Mean delay: = (0.1 + 2.1)/2=1.1time to issue “close request”close signalThe component in master library of PSCAD4.6Page 8Statistical breaker close例子: 檢查不同的合閘時間對暫態(tài)的影響注: 通常需要與“multiple run”一起使

4、用Page 9斷路器分閘電流截斷過程觸頭分離瞬間，電弧隨之建立截流總發(fā)生在電流過零時刻截流瞬間，暫態(tài)恢復電壓(TRV) 隨之出現(xiàn)截流成功與否取決于TRV及斷路器自身參數(shù)(重燃和重擊穿)PSCAD中創(chuàng)建的模型及例子“breaker arc”: 模擬電弧電阻的變化過程“reignition”: 模擬電弧重燃現(xiàn)象Restrike example: 重擊穿現(xiàn)象Page 10Breaker Arc模擬斷路器電弧三種方式：Thermal & dielectric recovery modelParameter modelArc-circuit interaction modelThe third one

5、is selected in PSCADPage 11Breaker Arc斷路器電?。杭冸娮栊裕?非線性影響電弧電阻的因數(shù):Power injected to the plasma channel by the systemCooling powerArc time constant of the breaker傳統(tǒng)模型：Mayr model: the arc near to the current zeroCassie model: the arc in the high current time intervalPage 12Breaker Arccontacts start to se

6、parate, arc resistance calculation startsArc voltage and currentarc resistancePage 13Breaker ArcExample: test circuit of “breaker arc”Page 14Breaker ArcMayr modelCassie model弧后電流(Post arc):源于TRV及過零瞬間電弧電阻未達到無窮大TRVTRV:主要由電源側 LC 電路造成Page 15Schavemaker modelBreaker ArcPage 16re-ignitionAfter the tempora

7、rily current interruption, if the dielectric withstand is less than TRV, the dielectric breakdown occurs.Problems:Voltage escalationExtending the arcing time, damaging the breakerCan happen on any breaker, most serious on VCB during small inductive current interruptionPage 17Arc re-ignitionPage 18Ar

8、c re-ignitioncontacts start to separate, arc formsArc voltage and currentBreaker control signalPage 19Arc re-ignitionExample: test circuit of “reignition”Page 20Arc re-ignitionSimulation results of “reignition”ignitioninterruption11 re-ignitions11 re-ignitionsTRV increases (voltage escalation)Page 2

9、1Arc restrike Restrike:The dielectric breakdown after 1/4 cycle of the power frequency, following interruption of a capacitive current at a normal current zeroResult: voltage escalation which can damage the breaker and other equipmentDifferences between re-ignition and restrikeOccurrence time:Re-ign

10、ition 1/4 fundamental cycle after current zeroMechanism:Re-ignition: high rate of rise of recovery voltage (RRRV)Restrike: the high voltage magnitude due to the trapped chargeCircuit:Re-ignition: inductive current (shunt reactor switching)Restrike: capacitive current (capacitor switching)Page 22Arc

11、restrike Current interruptedMultiple restrikesPage 23An arc forms at the fault point during Single Line to Ground fault (SLG). Primary arc: before breakers openSecondary arc: after the breakers tripSecondary arcA small current remains: the capacitive couple between the fault conductor and the “healt

12、h” conductorsExtinct at current zero, and may reignite due to fast rising recovery voltageVital to the Single Phase Auto-reclose (SPAR)Features Pure resistive, time viriable & hilghly nonlinearFault arcV-I cyclogram of secondary arcPage 24Model: the arc conductancePrimary arcSecondary arcThreshold v

13、oltage of re-ignitionFault arcPage 25Fault arcBreaker statusFault signalPage 26Fault arcExample: SPAR study and neutral ground reactor (NGR) designPage 27Fault arcSimulation resultsSLG appliedBreaker openSecondary arc currentRecovery voltageArc extinguishedPage 28Electric arc furnace (EAF)Power qual

14、ity problemsHarmonicsFlickervoltage imbalanceModeling:Modeled as a voltage source series with a resistorPower balance equation Page 29Electric arc furnace (EAF)Adjusting k1, k2, k3 to find a V/I characteristics which matches the measured one.Page 30Electric arc furnaceExample1: EAF with SVCPage 31Electric arc furnaceExample2: EAF with STATCOMPage 32References:“PSCAD model report-statistical breaker close”, shan“PSCA