电网畸变下两相静止坐标系的改进同步信号检测方法

IMPROVED METHOD OF SYNCHRONIZATION SIGNAL EXTRACTION IN TWO-PHASE STATIONARY REFERENCE FRAME UNDER GRID DISTORTION

新能源并网发电过程中逆变器需要获得同步的正弦信号,在电网电压不对称、畸变和频率变化等复杂工况下,电网电压含有正序、负序及谐波分量,对电网同步正弦信号的检测造成很大的干扰。基于此,提出在两相静止坐标系下,首先,将Hilbert变换与Clark变换相结合,利用简单的数学运算消除负序分量,从而分离出正序电压信号;其次,为了从分离的正序信号中提取出同步信号,将两相静止坐标系下的正序分量作为正弦幅值积分器(sinusoidal amplitude integrator,SAI)的输入信号,通过设计的复合正弦幅值积分器消除正序中的谐波分量;最后,分析频率变化对所提取同步信号的影响,构造正序分量频率自适应算法,使得同步信号的提取更加准确。仿真与实验结果表明,所提算法在复杂工况下可提取精确的电网同步正弦信号,具有良好的频率自适应特性。

The inverter needs to get synchronous sinusoidal signal in the process of grid connected power generation,the grid voltage contains the positive sequence,negative sequence and harmonic component under the complex condition of voltage asymmetry,which can cause the great interference to the detection of synchronous sinusoidal signal of the power grid. Based on this,a detection method in two-phase stationary reference frame is proposed. Firstly,the Hilbert transform is combined with the Clark transform,and the positive sequence voltage signal is separated by eliminated the negative sequence component using the simple mathematical operation. Secondly,in order to extract the synchronous signal from the separate positive sequence signal,the positive sequence component in the two-phase stationary reference frame as the input signal of the sine amplitude integrator(sinusoidal amplitude integrator,SAI),and the harmonic component in the positive sequence is eliminated by the composite sine amplitude integrator. Finally,the influence of frequency changes on the extracted synchronous signals is analyzed,and a frequency adaptive algorithm of positive sequence components is constructed which makes the extraction of synchronous signals more accurate. Simulation and experimental results show that the proposed algorithm can extract grid sinusoidal signals under complex conditions accuracy,and have good frequency adaptation characteristics.