不平衡电网电压下基于量子粒子群并网变流器功率/电流协调控制

在不平衡电网电压情况下,风电系统的不脱网运行会导致系统输出功率出现波动,并网电流出现显著的谐波畸变.由于恒定的输出功率和良好的并网电流质量无法同时实现,对此,提出一种基于量子粒子群(quantum particle swarm optimization, QPSO)优化算法来实现功率/电流协调控制的方案.在电流参考值的计算中引入调节系数α和β,并推导出功率波动幅值、电流谐波畸变率与调节系数的关系.为了同时兼顾功率和电流,以输出功率波动最小为控制目标,以电流谐波畸变率限值为约束条件,建立调节系数的优化模型.在不同类型的不平衡电压故障下,通过Matlab仿真实现功率/电流的协调控制,从而验证所提出方法的可行性及有效性.

Coordinate control of grid-connected converter based on QPSO under unbalanced grid voltage

Under unbalanced grid voltage, the ride-through operation of wind power systems will lead to fluctuations on output power and obvious harmonic distortion in grid-connected current. For the problem of that the constant output power and good current quality can not be achieved simultaneously, a power/current coordinate control scheme based on the quantum particle swarm optimization(QPSO) algorithm is proposed. The regulation coefficients α and β are introduced into the calculation of reference current, and the relationships between the amplitude of power fluctuations,the harmonic distortion rate of current and the regulation coefficients are deduced. In order to take the power and current into account, the optimization model of the regulation coefficients is established with the minimum fluctuations on output power as the control objective and the current harmonic distortion limit as the constraint condition. Under the condition of different types of voltage unbalance faults, the coordinate control of power and current is realized using Matlab, which verifies the feasibility and effectiveness of the proposed control scheme.