【作者】 朱勇；

【导师】 纪延超；

【作者基本信息】 哈尔滨工业大学 ， 电气工程， 2015， 硕士

【摘要】 随着风力发电的大规模发展,并网容量变得越来越大,但由于风力发电具有随机性、不可预测性,其对电网造成的影响已不可忽视。带蓄电池储能系统的STATCOM(简称STATCOM/BESS)结合了静止同步补偿器和蓄电池储能装置的优点,在风力发电输出功率波动时,可以提供必要的有功支持和无功补偿,起到削峰填谷的作用,并且当其应用在配电网中时,也可以减少负载波动对电网的冲击。因此,实现对STATCOM/BESS的有效控制至关重要。论文阐述了STATCOM/BESS四象限运行的原理及控制策略,建立了α-β坐标系、d-q坐标系下的系统主电路模型,着重分析了直接功率控制(Direct Power Control,DPC)。仿真表明,STATCOM/BESS在充/放电模式下,均可以实现无功补偿。传统开关表的DPC应用在STATCOM/BESS中时,无功功率波动较大。针对这一问题,论文综合考虑有功、无功跟踪精度,重新设计开关表。除此之外,采用新方法判断扇区,降低了实时计算量。仿真表明,改进开关表后DPC的有功、无功跟踪精度均较高。传统预测电流模型下DPC控制多用于PWM整流器中,对无功功率控制作用不明显,且未考虑不同场合下有功和无功重要性不同的问题。论文将无功功率误差纳入价值函数考虑范围,并引入功率跟踪权重系数,可以单独调节有功或无功的跟踪精度。仿真表明,改进后策略实现了对无功功率的有效控制,并且容易调节功率跟踪精度。传统预测功率下DPC控制可以在IGBT开关频率固定的情况下,实现对STATCOM/BESS系统的控制,但其缺点是对无功功率控制不足,且采用线性插值预测参考功率误差较大。论文首先将无功功率纳入控制目标,推导出STATCOM交流侧电压的新表达式;其次,采用二阶拉格朗日插值法代替线性插值预测STATCOM/BESS参考功率。仿真表明,在较低开关频率下,STATCOM/BESS输出功率波动小、跟踪准确。总体上,开关表的DPC优点在于结构简单、易于实现,其缺点是开关频率不固定;预测电流模型下DPC优点在于响应速度快、功率跟踪精度高,其缺点在于算法复杂;预测功率模型下DPC优点在于实现定频控制,缺点在于动态响应速度不及前两种控制策略。更多还原

【Abstract】 The grid capacity is increasing with the development of wind power generation. However, wind power generation is undulantly and unpredictable so that the impact on the power grid system has become increasingly evident. The STATCOM with battery energy storage system which called STATCOM/BESS combines the advantages of STATCOM and battery energy storage system. So it can control the active power and reactive power in the wind turbine with power fluctuation. When used in the distribution network, it can also reduce the impact on the power grid of load fluctuations. Thus, the realization of the effective control of STATCOM/BESS is extremely important.The principle and control strategy of STATCOM/BESS in the four quadrant operation are described in this paper. And, this paper establishes a main circuit model in the α-β and d-q coordinate system, analyzes the direct power control deeply. The simulation results show that STATCOM/BESS can achieve reactive power compensation under the charge or discharge mode.When traditional DPC control based on the switching table used in STATCOM/BESS, the reactive power has a periodic fluctuation. To solve this problem, this paper considers the active power and reactive power control accuracy, redesigns the switch table. In addition, a new method is adopted to judge the sector in order to reduce the computational quantity. The simulation results show that the active power and reactive power tracking accuracy is higher in the control of the improved switching table in DPC.Traditional DPC control based on predictive current model is mainly used in PWM rectifier. When used in STATCOM/BESS, the reactive power control effect is not ideal, and without considering the different situations of active and reactive power with different importance. This paper brings the reactive power error into account value function, and draw into the power tracking weight coefficient which can adjust the active power or reactive power tracking precision independently. The simulation shows that the improved strategy can control the reactive power effectively, and can adjust the tracking accuracy easily.Traditional DPC based on predictive power can realize the goal of fixed IGBT switching frequency in STATCOM/BESS system, but it can’t control reactive power well, and predicted referance power applying linear interpolation has big error. This paper takes reactive power into control strategy, deduces STATCOM AC side voltage expression. Then, this paper uses second order lagrange interpolation to predicte referance power. The simulation results show that the STATCOM/BESS output power fluctuation is small and accurately in low switching frequency.In conclusion,the advantages of DPC based on the switching table are that the structure is simple and easy to implement. At the same time, its disadvantage is that the switching frequency is not fixed. The DPC control based on predictive current model has fast response and high power tracking. On the other hand, its disadvantage is that the algorithm is too complexity. The DPC based on predictive power can realize fixed frequency control, but its disadvantage is that the dynamic response is not as fast as the first two strategies.更多还原