基于改进遗传算法含OLTC风电系统电压控制

为了克服风电波动使电压难以控制的问题，建立了以电压安全、网损和电压比调节裕度为目标的多有载调压变压器（on-load tap changer，OLTC）协调优化模型，以便带负荷切换电压比，使调压更灵活有效；结合风速Weibull分布和风电机组出力特性，将风电机组有功出力划分为若干区间，采用区间均值参与多OLTC协调优化，以确定电压比调节方案，并估计电压安全的概率；为改善遗传算法的全局收敛性，采用整数编码，综合概率生存和最优保留策略选择子代种群，并依据随机配位数组和变量约束内的随机数组对子代个体进行交叉变异，以用于风电系统中电压比优化调节方案计算。算例表明：合理选择目标权重和划分风电波动区间，电压比优化调节方案能确保较高的电压安全概率；改进遗传算法可有效地降低普通遗传算法就近取整的控制误差；电压安全目标的权重越小，风电出力划分的区间数越少，越不利于系统电压安全；风电机组有功出力越低的区间组合，目标函数值越小，系统电压越安全。该方法用于含风电的电力系统，可提高电压比优化调节方案电压控制的精度及电压安全的概率。

Voltage Control to Wind Power System with On-Load Tap Changer Based on Improved Genetic Algorithm

In order to overcome voltage control difficulty caused by wind power fluctuation, a multiple OLTC coordinated optimization model is proposed. The model targets on voltage security, power loss optimization and tap changer margin improvement, which aims to flexible tap changers switching under load and effective voltage regulation. The active output of wind turbine generators(WTGs) is divided into several sections according to the Weibull distribution of wind speed and WTG output characteristic. The sectional mean is applied to OLTC coordinated optimization for tap changer regulation scheme and estimation of voltage security probability. The global convergence of genetic algorithm is improved by integer coding and combination of probabilistic survival and optimal reservation strategy in offspring population selection. The crossover and mutation for individuals are based on random coordination array and random array within variation limits. The results show that improved genetic algorithm can effectively reduce round off error of original genetic algorithm. Reasonable selection of weight coefficient of objective function and dividing sections of wind power fluctuation can improve voltage security probability for optimization regulation scheme of tap changers. The smaller weight coefficient of voltage security and smaller number of divided sections yield lower probability of voltage security. The less active output of the WTGs for section combination yields smaller objective function value and better voltage security.