Research On Reactive Power And Voltage Control System Based On MCR

With the increasing demand for power supply and its quality brought along by the economic development, dynamic reactive power compensation equipments have become essential to the power system stability. Magnetic valve MCR has been widely used due to its high applied voltage level, low cost and high reliability. It can not only be used to compensate the load reactive power on the low voltage side of the transformer substation, but also has made a breakthrough in EHV and UHV grid.The valve sections of the MCR core work in saturated state, and its saturated degree can be regulated by changing the DC magnetic biasing, so that the capacity of the MCR is changed. First, a detailed analysis of structure and principle of the MCR, the derivation process of the mathematical model and equivalent circuit, and the compensation configuration with parallel capacitor or fixed reactor in reactive power and voltage control system are described in this thesis. Then, the harmonics, rate of regulation, and the active power loss are analyzed. That the harmonics cannot be eliminated by changing the control voltage is proved, and harmonic elimination method is discussed, particularly the multi-stage core structure; A DC power supply consisting of uncontrolled rectifier and Buck converter is presented for the low regulation rate in steady-state; Multi valve section core structure and core integration of three phase are discussed.The control model and parameter cannot be precise determinated because of the nolinear magnetic characteristic. Starting with the classic PID controller, nonlinear PID and active disturbances rejection controller (ADRC) based on it are studied. The simulation of capacity control results demonstrate that the ADRC can realize fast adjustment without overshoot in any operating state, its parameters are independent of the control model, and it can be implemented easily.Finally, an overall design of the reactive power and voltage control system based on MCR is conducted, and its kernel module is developed. The hardware based on LPC2132MPU consists of sampling and signal conditioning circuit, peripheral circuit of the processor, power supply circuit, and buttons and LCD; the software consists of the μC/OS-Ⅱ operating system and other user software such as data acquisition, reactive power calculation, control algorithm, switch judgment, fault processing, signal output, and LCD driver. The test results show that every function can be achieved.