Wind farm reactive-power control strategy for promoting transient stability of weak power grid integrated with wind power

Abstract

The invention discloses a wind farm reactive-power control strategy for promoting the transient stability of a large-scale weak power grid integrated with wind power. The strategy is divided into twoaspects of turbines and a wind farm, wherein in the turbine aspect, reactive-power priority control is adopted; in the wind farm aspect, based on a transient energy method, a transient unbalanced energy prediction value is calculated, a transient voltage stability margin is calculated, reactive power output of the different direct-drive wind turbines is adjusted, and a reactive power adjusting instruction is transmitted to each turbine. A strategy overall used by a controller is that according to interaction of the wind farm and an electric system in a system, reactive power control to the wind farm is decomposed into additional control to each draught fan. The control strategy needs no any additional hardware, the communication ability of a centralized control system of the wind farm andthe control strategy of direct drive wind turbines themselves are made full use of, the unreasonable fluctuation of overall reactive power voltage of the wind farm is avoided, and the transient stability performance of the weak power grid integrated with the wind farm can be effectively improved.

Description

technical field [0001] The invention relates to the field of transient stability of electric power systems, in particular to a strategy for improving the transient stability performance of large-scale wind power access under weak power grid conditions. Background technique [0002] At present, the long-distance power transmission system that has been formed in Gansu Power Grid has several major characteristics: "high proportion of wind and solar power, small load at the sending end, weak power grid at the sending end, and long distance of outgoing transmission lines". Send line delivery. In the normal operation mode, the randomness and volatility of wind power have caused problems such as difficulty in controlling the reactive power and voltage of the power grid. Since some wind turbines do not have low-voltage ride-through capability, the voltage drop of individual wind farms directly causes a large number of other wind farms connected to the grid at the substation to go o...

AI Technical Summary

Problems solved by technology

During the transient process of grid recovery after the fault is cleared, the wind turbine may temporarily lose control due to the large transient error of the phase-locked loop, absorbing reactive power from the grid

Moreover, during the recovery process, equipment such as transformers and squirrel cage motors will also absorb a large amount of reactive power from the grid, and the system is prone to voltage collapse due to reactive power imbalance.

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