Shan JiangManitoba HVDC Research Centre Winnipeg, Manitoba，Canada supportpscad.comPSCAD与电弧相关的模型及示例 断路器合闸 “statistical breaker close” 元件 断路器分闸 “breaker arc”元件 “reignition”元件 Restrike 重击穿 故障电弧 “fault arc”元件 电弧炉(EAF) “EAF”元件Page 2断路器合闸特点 断路器可以在基频周波的任意一点合闸 暂态因合闸点不同而异(Point On Wave - POW) 每相的合闸时间符合正态分布(normal distributed)Page 3断路器合闸Pre-insertion contactresistorMain contactPage 4TbTb+DtaTb+DtmDtaDtmclose requestclose pre-insertioncontactsclose main contactsT(sec)TaTm断路器合闸注: 每相的合闸时间符合正态分布Page 5Page 6Statistical breaker close均数 =2标准差 =1，对应出现概率 68.2% 标准差 =2，对应出现概率 95.4% 标准差 =3，对应出现概率 99.7% 标准差 =4，对应出现概率 99.999%Page 7Statistical 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: 检查不同的合闸时间对暂态的影响 注: 通常需要与“multiple run”一起使用Page 9断路器分闸电流截断过程 触头分离瞬间，电弧随之建立 截流总发生在电流过零时刻 截流瞬间，暂态恢复电压(TRV) 随之出现 截流成功与否取决于TRV及断路器自身参数(重燃和重击穿)PSCAD中创建的模型及例子 “breaker arc”: 模拟电弧电阻的变化过程 “reignition”: 模拟电弧重燃现象 Restrike example: 重击穿现象Page 10Breaker Arc模拟断路器电弧三种方式：1.Thermal & dielectric recovery model 2.Parameter model 3.Arc-circuit interaction modelThe third one is selected in PSCADPage 11Breaker Arc 断路器电弧：纯电阻性， 非线性 影响电弧电阻的因数: 1.Power injected to the plasma channel by the system 2.Cooling power 3.Arc time constant of the breaker传统模型：1.Mayr model: the arc near to the current zero2.Cassie model: the arc in the high current time intervalPage 12Breaker Arccontacts start to separate, arc resistance calculation startsArc voltage and currentarc resistancePage 13Breaker ArcExample: test circuit of “breaker arc”Page 14Breaker ArcMayr modelCassie model弧后电流(Post arc): 源于TRV及过零瞬间电 弧电阻未达 到无穷大TRVTRV: 主要由电源侧 LC 电路造成Page 15Schavemaker modelBreaker ArcPage 16re-ignition After the temporarily current interruption, if the dielectric withstand is less than TRV, the dielectric breakdown occurs. Problems: 1.Voltage escalation 2.Extending the arcing time, damaging the breaker Can happen on any breaker, most serious on VCB during small inductive current interruptionPage 17Arc re-ignitionPage 18Arc 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-ignitions 11 re-ignitionsTRV increases (voltage escalation)Page 21Arc restrike Restrike: The dielectric breakdown after 1/4 cycle of the power frequency, following interruption of a capacitive current at a normal current zero Result: voltage escalation which can damage the breaker and other equipmentDifferences between re-ignition and restrike Occurrence time: Re-ignition 1/4 fundamental cycle after current zero Mechanism: Re-ignition: high rate of rise of recovery voltage (RRRV) Restrike: the high voltage magnitude due to the trapped charge Circuit: Re-ignition: inductive current (shunt reactor switching) Restrike: capacitive current (capacitor switching)Page 22Arc restrike Current interruptedMultiple restrikesPage 23 An arc forms at the fault point during Single Line to Ground fault (SLG). Primary arc: before breakers open Secondary arc: after the breakers trip Secondary arc A small current remains: the capacitive couple between the fault conductor and the “health” conductors Extinct at current zero, and may reignite due to fast rising recovery voltage Vital to the Single Phase Auto-reclose (SPAR) Features Pure resistive, time viriable & hilghly nonlinearFault arcV-I cyclogram of secondary arcPage 24 Model: the arc conductance 1.Primary arc2.Secondary arc3.Threshold voltage 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 quality problems Harmonics Flicker voltage imbalanceModeling: Modeled as a voltage source series with a resistor Power 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:1.“PSCAD model report-statistical breaker close”, shan 2.“PSCAD model report-breaker ARC”, shan 3.“PSCAD model report-reignition and restrike”, shan 4.“PACAD model report-fault arc”, shan 5.“report of SPAR”, shan 6.“PSCAD Tuorial 5-Simulation of flicker due to an Arc Furnace load”, DharshanaThank you