A method for evaluating the effect of reactive power compensation device on suppressing commutation failure of lcc-hvdc system

Abstract

The invention discloses a method for evaluating the effect of a reactive power compensation device on suppressing the commutation failure of an LCC‑HVDC system. First, a fault inductance is used to simulate an AC fault at the AC bus connected to a DC inverter, and the start time and duration of the fault are set. time; on the premise of not putting in reactive power compensation device, the commutation failure probability is obtained; on the premise of putting in reactive power compensation device, the commutation failure probability is obtained; the abscissa is the fault inductance value, and the commutation failure probability is the ordinate , to obtain a graph of the commutation failure probability changing with the fault inductance; obtain the area ratio of the commutation failure probability according to the obtained graph; visually evaluate the reactive power compensation device to suppress the commutation failure of the LCC-HVDC system according to the area ratio of the commutation failure probability Effect. The above method can more intuitively evaluate the suppression effect of the reactive power compensation device on the commutation failure of the LCC‑HVDC system, so it can be applied in actual engineering tests.

Description

technical field [0001] The invention relates to the technical field of direct current power transmission, in particular to a method for evaluating the effect of a reactive power compensation device on suppressing the commutation failure of an LCC-HVDC system. Background technique [0002] The Line Commutated Converter High Voltage Direct Current (LCC-HVDC) system based on grid commutated converter has the advantages of large transmission power, fast controllable transmission power and low operating cost. It has been widely used in network engineering. However, since the converter of the LCC-HVDC system uses a thyristor without self-shutdown capability as the commutation element, on the one hand, its normal operation requires a certain strength of the AC system to provide the commutation voltage; on the other hand, the thyristor-based converter needs A large amount of reactive power is consumed, and the bus voltage is reduced. Static reactive power compensation devices such ...

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Problems solved by technology

However, since the converter of the LCC-HVDC system uses the thyristor without self-shutdown capability as the commutation element, on the one hand, its normal operation requires a certain strength of the AC system to provide the commutation voltage; on the other hand, the thyristor-based converter requires Consumes a large amount of reactive power, and the bus voltage decreases, and static reactive power compensation devices such as capacitors that compensate reactive power on the spot will reduce reactive power output. Therefore, once the AC system is weak or an AC fault occurs, the inverter of the LCC-HVDC system is easy to commutation failure

[0003] At present, the existing indicators for evaluating the immunity of LCC-HVDC system to commutation failure are mainly commutation failure immunity index and commutation failure probability index. Although these two indexes can describe the effect of reactive power compensation device on LCC-HVDC The inhibitory effect of system commutation failure, but it is difficult for operators to understand in actual engineering, and the evaluation process is not intuitive enough

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