Inverter protection circuit and protection method and device

Abstract

The invention discloses an inverter protection circuit. The circuit is used for protecting a voltage source inverter in an inverter with direct current fault ride-through capability, wherein the inverter is composed of a diode valve group or a current source type valve group unit and a voltage source type valve group unit, and the diode valve group or the current source type valve group unit and the voltage source type valve group unit are connected in series. A bypass thyristor valve group is connected in parallel with both ends of the inverter with direct current fault ride-through capability. The anode and the cathode of the bypass thyristor valve group are connected with the positive pole and the negative pole of the inverter with direct current fault ride-through capability respectively. The invention further discloses an inverter protection method. When the voltage source inverter detects that an alternating current or direct current system is failed and the voltage or current ofthe voltage source inverter exceeds a threshold value, the bypass thyristor valve group is input, and fault information is transmitted to a rectifier station. The rectifier station reduces the directcurrent voltage and reduces the direct current to zero. The bypass thyristor valve group is turned off due to current zero-crossing. The voltage source inverter protection circuit effectively solvesovervoltage and overcurrent problems caused by direct current charging of the voltage source inverter, and ensures the reliable operation of the voltage source inverter.

Description

Technical field [0001] The invention belongs to the fields of flexible direct current transmission and high voltage direct current transmission, and specifically relates to a converter protection circuit, a protection method and a device. Background technique [0002] The advantage of current source HVDC transmission based on thyristor is that the loss of the converter is small, and the DC system can be restarted by phase shifting when a DC line failure occurs; the disadvantage is that the inverter side converter works in an active inverter and cannot be connected Source system; commutation failure is likely to occur when the inverter side is connected to the weak AC system with disturbance; the reactive power consumption is large, the voltage and current harmonic content is high, and the filter device needs to be installed to provide reactive power and filtering. The advantages of DC transmission based on voltage source converters are high controllability and can be connected to...

AI Technical Summary

Problems solved by technology

The above solution will still cause serious overvoltage and overcurrent in the voltage source converter if extreme faults occur in the DC transmission system, such as grounding between the voltage source converter and the transformer, or a three-phase short circuit in the AC system

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