应用牛顿法的高压直流输电系统非特征谐波潮流算法

Non-Characteristic Harmonic Load Flow Algorithm Based on Newton-Raphson Method for High Voltage Direct Current System

针对高压直流输电系统非特征谐波潮流算法中非线性方程组具有变量多、维数高的特点,采用牛顿-拉夫逊算法迭代求解,提高了非特征谐波算法的收敛性,推导了换流装置交流侧三相电流和直流侧电压及Y、d换流变压器Δ绕组内零序环流的解析式.根据交、直流网络与换流装置的相互关系,组成换流站母线三相谐波电流平衡方程、直流网络谐波电流平衡方程,形成了修正方程式,以统一基波和特征谐波潮流结果为初值,运用牛顿-拉夫逊算法迭代求解全系统非线性方程组.采用该算法计算了南方电网云广±800 kV特高压直流输电系统非特征谐波潮流,计算结果合理,收敛性良好,证明了所提算法的正确性和有效性.

In the non-characteristic harmonic load flow algorithm for high voltage direct current （HVDC） system, the nonlinear equations are charactered by the multivariable and huge dimension. Newton-Raphson iterative method is applied to improve the convergence of the non-characteristic harmonic load flow algorithm. The analytic expressions of three phases AC current, DC voltage, and circulation current at A side in Y,d transformer are deduced. According to the relationship between the AC-DC network and converter device, balance equations of three-phase harmonic current of AC bus and DC network harmonic current are deduced, the modified equation for whole system is hence constructed and solved iteratively by taking the unified fundamental and characteristic harmonic load flow as the initial value. The non-characteristic harmonic load flows of China Southern Power Grid Yunguang -＋- 800 kV UHVDC transmission system are evaluated to verify the reasonableness and effectiveness.