Control method for reducing running risk of hybrid doubly-fed DC system under power grid fault

Abstract

The invention discloses a control method for reducing a running risk of a hybrid doubly-fed DC system under a power grid fault. The control method comprises the steps of setting a first control target, a second control target and a third control target, and calculating power running ranges Omega1, Omega2 and Omega3 corresponding to the control targets; showing the power running ranges Omega1, Omega2 and Omega3 in a PQ planar coordinate system to obtain different types of safety domains conforming to different control targets, calculating a passive power running point Q<VSC><*> of a voltage source converter based high voltage direct current (VSC-HVDC) inversion station under the power grid fault according to the types of the safety domains, calculating an inner ring current control instruction according to the passive power running point Q<VSC><*>, and outputting the inner ring current control instruction by the VSC-HVDC inversion station so as to achieve control on the running risk ofthe hybrid doubly-fed DC system under the power grid fault. The whole safe running of the hybrid doubly-fed DC system under the power grid fault is ensured by considering prevention of commutation failure of a line commutated converter high voltage direct current (LCC-HVDC) conversion station under the power grid fault of a receiving end, safety of the VSC-HVDC inversion station and safety constraint of a power frequency of a sending end.

Description

technical field [0001] The invention relates to the technical field of DC power transmission and distribution, in particular to a control method for reducing the operation risk of a hybrid double-infeed DC system under a grid fault. Background technique [0002] In the modern direct current transmission system, only the transmission link is direct current, and the power generation system (sending end system) and power consumption system (receiving end system) are still alternating current. The hybrid double-infeed DC system is a DC transmission system, and its topology is as follows: figure 1 As shown, it is mainly composed of LCC-HVDC (line commutated converter high voltage direct current, grid commutated high voltage direct current transmission) converter station and VSC-HVDC (voltage source converter based high voltage direct current, high voltage direct current transmission based on voltage source converter) ) inverter station, the LCC-HVDC converter station is used to ...

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Problems solved by technology

[0006] (3) Increase the cut-off angle γ setting value of the LCC-HVDC converter station. Under steady-state conditions, increasing the arc-off angle of the inverter station can effectively reduce the risk of commutation failure, but it will lead to a decrease in the transmission power of the DC system and reactive power consumption. Increase, reduce DC system operating economy

[0008] At present, although there is some research on the control strategy of the hybrid double-infeed DC system, most of them aim at the maximum reactive power output capability of the VSC-HVDC system as the control goal, and there is a lack of control strategies for the hybrid double-infeed DC system under different control objectives. Quantitative research on reactive power control without considering the overall safety of hybrid double-fed DC systems

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