考虑风电机组无功特性的安全约束机组组合方法

Security-constrained Unit Commitment Considering Reactive Power Performance of Wind Turbine Generator

随着风能的广泛使用,安排发电计划时更多的风电机组将会被引入,这对传统的机组组合提出了新要求。风电出力具有很强的波动性,将风电出力按一个区间放入原模型中更显合理。另外,异步风电机组的结构与普通火电机组不同,异步电机发电的同时要吸收一定的无功功率,因此模型用交流潮流约束更合理。由此建立的是一个非线性混合整数问题模型,为了提高计算效率,将问题分解为2层优化子问题,第1层为无网络约束的机组组合问题,第2层为以网损最小为目标函数的交流网络约束最优潮流问题,对于最优潮流算完后仍有电压或线路潮流越限的,将形成一些新的约束返回原问题。考虑到普通异步风电机组的大量使用,在处理约束问题时对风电机组采用无功功率—电压模型,避免出现无功不足而导致电压越限。以添加了风电机组的IEEE 57节点测试系统为算例,验证了该方法的可行性。

As wind power is widely used, more and more wind power generators will be considered in the unit commitment planning. This imposes new requirements on the traditional security constraints unit commitment （SCUC）. As wind power keeps fluctuating, it is more reasonable to be modelled as a region. Besides, the asynchronous generator used in the wine] turbine is di{ferent from that o{ thermal generator. It absorbs reactive power so that the unit commitment （UC） model should use AC security constraints. The model is a nonlinear and mixed-integer problem. For the sake of computational efficiency, the problem will be decomposed into two layers. The upper-layer is UC without network constraints. The sub-layer is optimal power flow （OPF） problem with AC constraints and objective o{ minimizing the network loss. If some variables are out of limits, some new constraints shall be added to the UC and security constraints optimal power flow （SCOPF）. As induction generator is widely used, the method uses an reactive power-voltage model to avoid reactive power overflow issue. An IEEE 57- bus system with a wind power generator is used for testing this method. Simulation results show that the proposed method is effective.