Design Of Reactive Power Compensation Controller Based On FFT Algorithm

In electric power system, a reasonable allocation of reactive power is critical for the normal operation of the power supply system and the load. Since the impedance of power system network element is mainly inductive, active power can be delivered in a fairly wide range through producing a certain phase between power transmission end and the receiving end, and as a result of the transmission of reactive power requires a difference between the terminal voltage, which can only be achieved in a relatively narrow range.In the power grid, most of the network components and load need to consume reactive power, so it is not reasonable and possible to transmit these reactive power through a long distance. Therefore, it requires real-time detection of reactive power to compensate reactive power where reactive power is consumed. In this paper,the dynamic reactive power compensation controller is designed based on the dynamic reactive power detection algorithms and control theory research.In this paper, the DSP and FPGA dual core structures are used in the hardware.Benefit from the character of a logical combination of pure hardware circuit of FPGA,it has great advantages in parallel computing and development flexibility, at the same time use the method of dual-core DSP and FPGA co-processing because of the poor external interface of FPGA, a parallel and serial channel is built to ensure the efficient and stable communication between dual core. DSP is mainly for data acquisition,general data processing and real-time display of voltage and current waveforms of power system with abundant peripheral resources while FPGA is responsible for the parallel working construction of core algorithm and control by building a Nios II control core and algorithm core in a chip. Fast Fourier transform(FFT) algorithm is used to analyze system reactive power, which can analyze system harmonics in real time, while control strategy adopts reactive power and voltage strategy based on nine-zone diagram of fuzzy theory. On the output structure, the combination method of using thyristor control capacitor(TSC) thyristor controlled reactor(TCR) realizes continuous adjustment of the reactive power. On the hardware structure, analog signal acquisition circuit and core control circuit are separated, and the interference of the analog signal to digital signal is reduced, moreover the core control board adopts four layers PCB routing which greatly improves the stability of the system.Through the simulation of analog circuits in PSPICE and construction of analog circuits, feasibility of the program was verified, finally analog signal acquisition board and core control board are successfully produced. With the building of systemplatform, the system can accurately collect the current and voltage signal, and carry out reactive power calculation and spectrum analysis. The function of the system is basically realized.