对单级式三相光伏并网逆变器的数学模型进行了分析.在此基础上,将系统中的并网变压器作为无功负载引入控制系统,提出了基于电压定向矢量控制的对变压器吸收的无功功率进行补偿的控制算法,提高了系统输出电能的功率因数.另外,针对传统滑模频率偏移法在电网运行于非额定频率时输出功率因数下降的缺点,将滑模频率偏移算法曲线设计为二次曲线,提高了系统在非额定频率运行时的功率因数.最后通过仿真和实验,验证了上述算法的可行性和正确性.%The mathematical model of the single-stage grid-connected photovoltaic inverter is analyzed for unity power factor output. The grid-connected transformer is considered as a reactive load in this model and a reactive power compensation algorithm based on voltage-oriented vector control is introduced for it. Under the control of conventional SMS (Slip-Mode frequency Shift) algorithm, the power factor output will decrease when the power system frequency deviates. Therefore,a quadratic curve is adopted in SMS algorithm. Simulations and experiments validate the feasibility and correctness of the proposed algorithm.
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