Kisan Gaji na Shunt Reactor a Circuit Breakers
Shunt-Reactor Switching: A Common Practice in Inductive-Load Switching
Shunt-reactor switching ya zama wani babban tushen da ake yi a cikin tushen shiga kashi. An fito shunt reactors don bayar da capacitance na kabeli mai kasa, kuma an shiga ko kawo har zuwa saboda muhimmin yadda aiki. Saboda haka, za a iya tabbatar da shunt reactor daidai da lumped circuit element tare da stray capacitance, za a iya haɗa tsarin aiki zuwa LC (inductor-capacitor) circuit.
Voltage Oscillations at Interruption
A lokacin da ake kawo, wanda yana da current chopping, LC circuit yana bari voltage oscillations. Maximum voltage, , yana samun mafi yawa wanda shi ne 1 per unit (p.u.) na system voltage tare da abin da ake bayar da current chopping. Tushen, single-frequency oscillatory transient recovery voltage (TRV) yana da ma'ana mai kalmomi, IEC 62271-110 ta kawo girman ma'ana daga 6.8 kHz a rated voltage na 72.5 kV zuwa 1.5 kHz a 800 kV.
Short Arcing Time and Re-ignition Risk
Duk da cewa shi ne kamar tushen shiga kashi, reactor current yana da gaba kafin ake kawo. Wannan gaban da ke faru yana nuna cewa kawo yana faru ba a lokacin da arcing time yana da gaba. Wannan gaban da ke faru yana nuna cewa clearance da ke cikin circuit-breaker ba suka shiga rike mai kyau a lokacin da current zero point. Idan wannan yana faru, breakdown yana faru, wanda yake buƙata wa re-ignition. A wannan lokaci, re-ignition yana nufin cewa high-frequency TRV yana buƙata wa faru a kan farkon power-frequency period bayan kawo.
Low Energy Discharge in Inductive Re-ignition
Ba kamar restrike a capacitive circuits, energy da ake bayar da ita a inductive re-ignition discharge yana da gaba, wanda yake da discharge na stray capacitance. Yana kawo re-ignition current mai kalmomi, kuma clearance yana iya ko ba iya jin daidai. A lokacin da re-ignition current yana kawo, opening gap yana samun breakdown voltage mai kadan. Bayan re-ignition current yana kawo, subsequent higher TRV yana iya buƙata wa re-ignition. Wannan yana da nasara cewa, a lokacin da conducting period mai kadan, power-frequency current a reactor yana da gaba, wanda yake buƙata wa second TRV zuwa mafi yawa da ma'ana mai kadan.
Multiple Re-ignitions and Voltage Escalation
Sekwens na re-ignitions yana nufin multiple re-ignitions, kuma gradual increase a re-ignition voltage value yana nufin (inductive) voltage escalation. Multiple re-ignitions yana da nasara ga gas and oil circuit breakers, wanda shi ne saboda haka shunt-reactor switching yana nufin "a circuit-breaker's nightmare." Wannan shine hasashen da shi ne saboda shunt-reactor switching yana da aiki masu rana, wanda yake buƙata wa wucin stress ga wasu devices.
Analysis of SF6 Circuit Breaker Test with Multiple Re-ignitions
A cikin figure da aka bayar da SF6 circuit breaker test, seven re-ignitions ana iya duba kafin ake samu recovery. Karkashin re-ignition, re-ignition current mai kalmomi yana da shiga kashi a lokacin da clearance yana da shiga kashi a lokacin da 100 μs. Maximum voltage da aka samun a cikin load reactor yana da 2.3 p.u.. Ba da re-ignitions, maximum voltage yana da shiga kashi a 1.08 p.u. saboda chopping current mai gaba. Peak value na transient recovery voltage (TRV) yana da 3.3 p.u..
Key Observations:
Multiple Re-ignitions: Duk da cewa chopping current yana da gaba, load voltage yana da shiga kashi a lokacin da multiple re-ignitions. Wannan yana nuna muhimmin impact na re-ignitions a voltage levels na system.
High-Frequency Re-ignition Current: Re-ignition current yana da kalmomi mai kalmomi, wanda yake da shiga kashi a lokacin da clearance yana da shiga kashi a lokacin da 100 μs. Wannan gaban da ke faru yana nuna cewa voltage yana da shiga kashi a lokacin da kalmomi, wanda yake buƙata wa subsequent re-ignitions.
Voltage Escalation: Maximum voltage a cikin load reactor yana da 2.3 p.u., wanda yake da shiga kashi a kan expected voltage ba da re-ignitions (1.08 p.u.). Peak TRV value na 3.3 p.u. yana nuna severity na voltage escalation da multiple re-ignitions suka buƙata.
Preventing Multiple Re-ignitions in Shunt-Reactor Switching
Multiple re-ignitions a shunt-reactor switching zai iya dogara da controlled switching techniques. Ba da cewa ake amfani da random contact separation, controlled switching yana tabbatar da contacts suka separate well in advance of the current zero point. Wannan approach yana da fa'idota:
Avoiding Short Arcing Times: By separating the contacts in advance, the arcing time is extended, allowing the gap to reach sufficient spacing before the current naturally reaches zero. This reduces the risk of re-ignition, as the gap is better prepared to withstand the transient recovery voltage (TRV).
Timely Interruption: Controlled switching ensures that the interruption occurs when the gap has already reached a sufficient spacing. This timing minimizes the likelihood of re-ignition and helps maintain stable system performance.
Reduced Voltage Escalation: By preventing re-ignitions, controlled switching also mitigates the risk of voltage escalation. The system voltage remains closer to the expected values, reducing stress on insulation and other components.
Benefits of Controlled Switching
Enhanced Reliability: Controlled switching improves the overall reliability of the circuit breaker, especially in applications involving shunt reactors. It reduces the occurrence of multiple re-ignitions, which can otherwise lead to equipment damage or system instability.
Improved Performance: By avoiding re-ignitions, controlled switching ensures that the circuit breaker operates within its design parameters, maintaining optimal performance and extending the lifespan of the equipment.
Cost Savings: Reducing the frequency of re-ignitions can lead to cost savings by minimizing maintenance requirements and preventing potential equipment failures.
