计及谐波频率特征的含风电配电网充分式电流幅值差动保护

Sufficient Current Amplitude Differential Protection Considering Frequency Characteristic of Harmonics for Distribution Network with Wind Power

风电接入配电网给传统的配电网保护方案带来挑战。考虑到配电网结构的改变和通信条件的相对落后,提取了绝大多数故障电流幅值的普遍特征,提出充分式电流幅值差动保护思想。以双馈式感应风力发电机为风电接入配电网的代表形式,分析其在低电压穿越控制方式下的短路电流谐波频率特性;提出频谱指标的概念表示谐波分量的占比大小,衡量故障时风机侧与大系统侧电流谐波频率特征的差异,基于此提出计及频谱指标的充分式电流幅值差动保护判据,对充分式保护方案进行补充。改进的保护方案更加充分地利用故障电流幅值和谐波频率信息,提高了保护的灵敏性和可靠性。最后,基于MATLAB/Simulink进行仿真,验证了该保护方案的合理性。

Wind power integrated into distribution network poses challenges to traditional protection schemes in distribution network. Considering the change of distribution network structure and the relative backwardness of the communication conditions,this paper extracts the general characteristics of the most fault current amplitudes, and puts forward the principle of sufficient current amplitude differential protection. Taking the doubly-fed induction wind generator as the representative form of wind power integrated into distribution network, the harmonic frequency characteristics of short-circuit current with the control strategy of low voltage ride through are analyzed. The concept of spectrum index is proposed to measure the proportion of harmonic components,so as to measure the frequency characteristic difference of current harmonic between the wind power side and the power system side. Based on this, a new criterion of sufficient current amplitude differential protection considering the harmonic frequency characteristics is proposed as the supplementary of the sufficient protection scheme. The improved protection scheme makes full use of the fault current amplitude and harmonic frequency information, and improves the sensitivity and reliability of the protection.Finally, the rationality of the protection scheme is verified by MATLAB/Simulink simulation.