Energy-storage type static synchronous compensation device and direct-current transmission commutation failure suppression method

Abstract

The invention discloses an energy storage type static synchronous compensation device and a direct-current transmission commutation failure suppression method, The large-capacity energy-storage type static synchronous compensation device is composed of a plurality of energy-storage type static synchronous compensators which are connected in parallel. The energy-storage type static synchronous compensator (1) comprises an energy storage unit, a DC / DC converter, a capacitor and a voltage source converter. The energy storage static synchronous compensator is connected to the AC bus of the receiving end converter station of the UHVDC transmission system through a transformer. The inductor is serially connected to the AC bus bar of the energy storage type static synchronous compensation deviceand the receiving end converter station, The large-capacity energy storage type static synchronous compensation device operates in a voltage source mode, and can provide sufficient voltage support forthe receiving end AC bus bar of the receiving end converter station to ensure normal commutation, thereby restraining commutation failure caused by fault of the receiving end AC power network and preventing cascading failure caused by commutation failure to the UHVDC transmission system.

Description

technical field [0001] The invention relates to the field of ultra-high direct current transmission, in particular to an energy storage type static synchronous compensation device and a method for suppressing commutation failure of ultra-high voltage direct current transmission. Background technique [0002] As the most typical system failure of DC transmission system, commutation failure has become one of the major problems faced by the development of UHV DC transmission system. On the inverter side of the transmission system, the voltage drop of the AC bus, the voltage waveform distortion caused by harmonics, the sudden increase of the DC current, and the offset of the zero-crossing point of the commutation voltage caused by the three-phase asymmetrical fault may cause commutation failure. Commutation failure will lead to adverse factors such as DC voltage drop, short-term increase of DC current, and waveform distortion, which will affect the stable operation of the system...

AI Technical Summary

Problems solved by technology

When STATCOM is applied to suppress commutation failures in HVDC systems, it usually requires a larger reactive power output, which requires a larger DC side capacitance value, and a larger DC side capacitance value will affect the dynamic tracking performance of STATCOM; if the STATCOM DC side The value of the capacitor is small, and the excessive reactive power output will cause the voltage fluctuation of the DC side to be too large, so that the reactive power output contains a large number of harmonics, which will affect the quality of the output current. In addition, the increase of harmonics will inevitably lead to STATCOM The increase of active power loss will weaken its reactive power compensation capability

Therefore, STATCOM has shortcomings such as the quality of output voltage and current being greatly affected by the capacitance value of the DC side, the reactive power output capacity is greatly affected by the fluctuation of the grid voltage, and the effect of only compensating reactive power leads to unsatisfactory grid voltage stability, which greatly limits its application in HVDC system replacement. Applications in the Field of Phase Failure Suppression

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