摘要
针对电网电压骤升后光伏电站并网点电压远高于额定值运行的场景,研究光伏变流器基于自身无功容量对并网点电压进行调节时光伏并网系统的小干扰稳定性变化。首先,从电力系统功率传输理论的角度推导得到并网点电压/无功灵敏度,给出并网变流器抑制光伏电站并网点电压升高的机理;其次,建立光伏并网系统的小信号模型,并据此对光伏系统无功电压调节前后进行特征值分析。研究结果表明,电网电压骤升后增加并网变流器吸收的无功功率有助于改善光伏系统的小干扰稳定性。最后,通过时域仿真验证了本研究结论及其理论分析的正确性。
Considering the situation that voltage at grid-connected point of photovoltaic power station was much higher than the rated value after grid voltage swell, the small signal stability change of photovoltaic grid-connected system was studied when the voltage at the point of common coupling(PCC) was regulated based on its reactive capacity. Firstly, the voltage/reactive power sensitivity of grid-connected point was deduced from the perspective of power transmission theory, and the mechanism of suppressing voltage rise at PCC by photovoltaic converter was introduced. Secondly, a small signal model of photovoltaic grid-connected system was established, and the eigenvalue analysis of PV system before and after reactive power and voltage regulation was carried out accordingly. The results showed that the increase of reactive power absorbed by the grid-connected converter after the grid voltage swell contributed to the improvement of the small signal stability of PV system. Finally, the time-domain simulation results verified the correctness of the conclusion and theoretical analysis.
引文
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