| In the progress of current society, the growing shortage of fossil energy and the environment worsening plague us at the same time. In this case, solar energy which has the advantages such as cleanness, inexhaustible, large amount gets the favour of researchers. However, instability, and grid-connected photovoltaic(PV) solar equipment high cost, low utilization factor restricts the popularization and application of PV power generation. Negative factors such as instability of solar energy, high cost and low utilization of grid-connected PV solar equipment restrict the popularization and application of photovoltaic power generation. On the other hand, with the rapid development of power electronic technology, various nonlinear devices bring convenience to people’s living, a lot of harmonic and reactive current component are poured into the power system meanwhile. Not only do they lower the energy efficiency, but also harmonic and reactive power are security threats of the system. Power quality of the electric power system becomes another problem urgently need to be solved. As a kind of active compensation device, the active power filter(APF) has received much attention of the institutes and universities. After years of research and development, the theoretical basis of APF has already become perfect. The optimization of control strategy is the chief task at the present stage. In the meantime, the APF is up against many development handicaps, for instance, costly price and few features.At first, many features of APF and the PV grid-connected inverter were analyzed in this paper, such as the merits, demerits, and the problems, prospects in the development, working principle and structure characteristics. The possibility and significance of combined control of APF and PV grid-connected inverter was discussed also. This paper proposed a combined control system of APF and PV grid-connected inverter. Then connecting the ip-iq harmonic detection technology based on the instantaneous reactive power theory, this paper analyzed the calculating method of instruction current of the combined control system. Finally as to the phase-locked loop(PLL) in instruction current calculating, its principle and software realization method were introduced in detail, which makes up the defect that can not predict the single cycle frequency change of zero-cross detection. For the instruction current tracking control, the hysteresis SVPWM control strategy, which select the optimal output voltage vector according to position in space of error current and the reference voltage space vector to limit the error within the allowable range and achieve the purpose of the current tracking control, is simple in implementation, have good tracking performance and small switch loss. In addition, DC side voltage proportional integral control method was briefly introduced.This paper set up a system simulation model which mainly includes the instruction current calculating module, current tracking control module and the main circuit that has the diode bridge rectifier with resistance load and so on. It made the simulation respectively in separate state of APF and combined control condition of APF and grid-connected inverter, and the simulation results verified the validity of the system.The paper set up a hardware experiment platform which includes signal detection circuit, fault processing circuit, protect circuit, phase shift circuit and main circuit that has the diode bridge rectifier with resistance load and so on for the combined control system based on DSP2812, and gave the circuit diagram of each part in detail. It achieved the software phase-locked loop calculation, instruction current detecting and current tracking control and so on by writing software on DSP. Each part of the software flow chart was introduced too. Finally experiment results indicated the feasibility of the control system proposed in this paper. |
PDF Full Text Request