调制模型预测控制在基于STATCOM的煤矿电能质量治理的应用研究

Research on the application of modulated model predictive control in coal mine power quality management based on STATCOM

  • 摘要: 大量电力电子设备及非线性负载接入煤矿电网,使得煤矿电网中存在大量电流谐波及无功功率,严重危害煤矿电网电能质量。传统电能质量治理策略大多采用比例积分(PI)调节器对静止同步补偿器(STATCOM)进行控制,以实现谐波抑制和无功补偿,但其参数难以调节且动态响应慢。针对上述问题,提出了一种基于调制模型预测控制(M2PC)的STATCOM控制策略。首先,采用ipiq法检测出电网中的谐波电流和无功电流作为M2PC的参考电流;其次,根据参考电流及STATCOM数学模型计算出每个扇区的2个有效矢量和零矢量的占空比及扇区代价函数;然后,通过最小化代价函数得到最佳扇区和该扇区所对应的2个最佳有效矢量和零矢量的占空比;最后,根据空间矢量调制(SVM)方式分配开关脉冲,实现固定的开关频率,从而控制STATCOM发出补偿电流,以抵消电网中的谐波电流与无功电流。仿真和实验结果表明:投入基于M2PC的STATCOM前,电网侧电流畸变严重,电网侧无功功率波动大,电网侧功率因数存在波动且小于1;投入基于M2PC的STATCOM后,由于STATCOM补偿了电网侧谐波电流,使得电网侧电流总谐波畸变率(THD)大幅度降低,且由于STATCOM补偿了负载所需无功功率,电网侧无功功率基本保持为0,电网侧功率因数稳定为1,有效改善了电能质量。

     

    Abstract: A large number of power electronic devices and nonlinear loads are connected to the coal mine power grid, causing a large amount of current harmonics and reactive power in the coal mine power grid. It seriously endangers the power quality of the coal mine power grid. The traditional coal mine power quality control strategies mostly use proportional integral (PI) regulators to control static synchronous compensator (STATCOM) to achieve harmonic suppression and reactive power compensation. But their parameters are difficult to adjust and their dynamic response is slow. In order to solve the above problems, a STATCOM control strategy based on modulated model predictive control (M2PC) is proposed. Firstly, the ip-iq method is used to detect the harmonic current and reactive current in the power grid as the reference current for M2PC. Secondly, based on the reference current and STATCOM mathematical model, the duty cycle and sector cost function of the two effective vectors and zero vectors for each sector is calculated. Thirdly, by minimizing the cost function, the optimal sector and the duty cycle of the two optimal effective vectors and zero vectors corresponding to that sector are obtained. Finally, according to the space vector modulation (SVM) method, switching pulses are allocated to achieve a fixed switching frequency. It thereby controls STATCOM to emit compensation current to offset harmonic and reactive currents in the power grid. The simulation and experimental results show that before the adopting of M2PC based STATCOM, the grid side current distortion is severe, the reactive power fluctuation on the grid side is large. The power factor on the grid side fluctuates and is less than 1. After the adopting of M2PC based STATCOM, the total harmonic distortion rate (THD) of the grid side current is significantly reduced due to STATCOM compensating for the harmonic current on the grid side. Moreover, due to STATCOM compensating for the required reactive power of the load, the reactive power on the grid side remains basically 0. The power factor on the grid side remains stable at 1, effectively improving power quality.

     

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