基于正序基波电压合成相量的发电机并网条件核算法

The Condition Verification of Generator Paralleling Based on the Synthetic Phasor of Positive Sequence Fundamental Voltage

考虑到三相电压或多或少有些不平衡,提出了一种新的基于正序基波电压合成相量的发电机并网条件核算法。采用离散傅氏法求得正序基波电压合成相量的估计值,通过寻找处在相邻周期的相角差为零的2个合成相量的估计值来实现频率的精确估计,然后利用双线性插值法对采样数据进行同步化处理,以获取更加准确的合成相量。同时,建立了一种基于滑差分段恒加速的预报模型,并利用越前角和超越前角来确定发送并网信号的时机。试验表明:文中提出的方法能够在三相电压不平衡和滑差角速度波动时预报出合理的并网时机。

Considering the imbalance of three phase voltages, a new arithmetic which verifies the generator paralleling based on the synthetic phasor of positive sequence fundamental voltage is proposed. The approximate synthetic phasor of positive sequence fundamental voltage is figured out by DFT, the actual frequency of the synthetic phasor is precisely estimated by searching two approximate synthetic phasors that have the same angle and are in adjacent period, and then the sample data is synchronized by bilinear interpolation in order to acquire more precise synthetic phasor. Meanwhile, a new forecasting model is built based on the subsection constant acceleration of slip frequency, and the time when the signal of generator paralleling is send is affirmed by means of leading angle forecasting and exceeded leading angle forecasting. The proposed method has been simulated and it proves that rational time of generator paralleling can be forecast in the case of the imbalance of three phase voltages and the fluctuation of slip frequency.