The Design And Implementation Of Distributed Grid-connected PV System Power Adjusting Device

With the increasingly serious energy crisis and environmental pollution, many countries are increasing the development of research on green renewable energy to seek more method, which can effectively solve the problem of energy and environment. For its clean and inexhaustible features, solar energy has become a key research topic of the vast power scientific workers, and key targets for assistance in the national policies and the smart grid construction. Because the received solar energy density of photovoltaic power generation system is intermittent and random, the PV grid-connected system exist a series of problems. In order to improve the stability of the photovoltaic grid-connected power system’s operation and extend its functions, this paper uses TI Company’s DSP chip TMS320F28335to develop a set of power adjusting device, which can provide active power tracking, reactive power compensation and harmonic elimination etc.Based on the theory of three-phase instantaneous reactive power, the power adjusting device synthesizes the compensation current of active power, reactive power and harmonic to achieve multifunction compensation functions. This device uses a method of ip-iq current detection. Firstly, it decomposes the current instantaneous value into active power current and inactive power current by coordinate transformation and goes through Low pass filter to remove the AC component. Then it will get the compensation current of reactive power compensation and harmonic by minus actual current. At last, it merges the active power compensation current into synthetic instruction current, and completes the function of reactive power compensation, active power tracking and harmonic elimination.This paper analyzes the flow management of distributed photovoltaic grid-connected power system, three-phase instantaneous reactive power theory, ip-iq current detection method and harmonic treatment technology. Based on these theories, it completes the design of hardware circuit, software programming of the system, the simulation of control algorithm based on Simulink and the overall debugging of system.