Synchronous condenser start-up grid-connected circuit and control method based on pre-connected large impedance

Abstract

The invention discloses a preaccess high impedance-based synchronous condenser starting grid-connected circuit and a control circuit. The circuit comprises a synchronous condenser, a machine-end mainAC circuit breaker, an AC three-phase transformer, a power grid and a preaccess circuit, wherein the preaccess circuit comprises a preaccess AC circuit breaker, a preaccess resistor and a preaccess inductor which are sequentially connected, wherein an AC outlet end of the synchronous condenser is connected with the machine-end main AC circuit breaker; the other side of the machine-end main AC circuit breaker is connected with the AC three-phase transformer; the other side of the AC three-phase transformer is connected with the AC power grid; and the preaccess circuit is connected with the machine-end main AC circuit breaker in parallel. According to the preaccess high impedance-based synchronous condenser starting grid-connected circuit, impulse voltage and permanent magnet current generated in the starting process are reduced, and smooth starting and grid-connection of the synchronous condenser are achieved.

Description

technical field [0001] The invention belongs to the start-up control technology of a synchronous condenser, in particular to a start-up grid-connected circuit and a control method for a synchronous condenser based on pre-connected large impedance. Background technique [0002] The synchronous condenser can provide reactive power compensation to the grid, and has high application value in the field of high-voltage direct current transmission. The synchronous condenser is a rotating motor. Its operation and maintenance are more complicated than static var compensation equipment. It is likely that there will be a large excitation inrush current and surge voltage during the start-up process of grid connection. If the start-up control method is improper, it will cause an impact on the power grid. Therefore, it is meaningful to design a suitable start-up grid-connection circuit and an effective timing start-up grid-connection control method for synchronous condensers. [0003] Ai...

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Problems solved by technology

[0003] Aiming at the start-up and grid-connected control of synchronous condensers, the existing schemes mainly have the following problems: 1) The control of starting the excitation system on the rotor side of the synchronous condenser, loading the armature voltage on the stator side, loading the excitation voltage on the rotor side, and unlocking the rotation of the rotor is not clear Sequence; 2) The voltage setting value of the excitation system is always kept at the rated value or changes from zero to the rated value when the start command is issued. The specific calculation method of the voltage setting value of the excitation system is not clear, which will cause obvious problems in the starting process. Impulse voltage and excitation inrush current; 3) At the moment when the AC circuit breaker at the machine end of the synchronous condenser is closed, there will be obvious impulse voltage and excitation inrush current at the grid connection point; 4) There is no specific method to clearly limit the impulse voltage and excitation inrush current at the grid connection point

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