Control structure and control method of photovoltaic grid connected inverter

Abstract

The invention belongs to the technical field of the power grid control, and especially relates to a control structure and control method of a photovoltaic grid-connected inverter. The control structure of the photovoltaic grid-connected inverter can realize the synchronous control effect on the grid-connected voltage and current by an inverter and improve the power factor, and further can effectively inhibit the harmonic pollution, eliminate steady-state error, resist system power grid frequency interface, and improve the stability of the system. The inverter created by the invention has goodgain effect, a retention signal is used for improving a tracking effect, and the capacity of resisting power grid frequency disturbance of the inverter is improved by optimizing a system function; thegrid-connected inverter can effectively eliminate the steady-state error, the capacity of resisting system power grid frequency interference is enhanced by enlarging the bandwidth, and the bad influence caused by resisting the power grid frequency change by the inverter is enhanced through the control function; the system stability is improved by enlarging the system bandwidth, and the relative precision of the system is improved.

Description

technical field [0001] The invention belongs to the technical field of grid control, and in particular relates to a control structure and a control method of a photovoltaic grid-connected inverter. Background technique [0002] In the connection network between the photovoltaic grid and the distribution network, the grid-connected inverter, as the core of energy conversion or control, is a key device that affects the performance of the entire system. Wave pollution and abnormal power parameters, if not well controlled, will have a serious impact on the performance of the inverter, eventually leading to a decline in the overall performance of the photovoltaic grid. During the operation of the inverter, its various parameters will continue to change with time and the real-time status of the power grid. Therefore, how to reasonably control the various functions of the inverter to improve the control performance and reduce the power grid system and inverter. Adverse effects bet...

AI Technical Summary

Problems solved by technology

The most widely used inverter control method or structure in the existing technology, such as PI control, voltage source control and other methods, its core is to study and control the inverter as a whole as a linear system. In actual situations, the inverter The parameters of the inverter itself and the external parameters of the inverter are constantly changing, that is, changing nonlinearly. Therefore, in a relatively stable grid system or operating environment, the inverter controlled by this method can meet the operating requirements. However, the inverter will not be able to perfectly realize its control function under the condition that there is great interference in the photovoltaic power grid and the parameters change frequently. With the continuous development and progress of photovoltaic technology, the scale of photovoltaic power grid is getting larger and larger, and The number of photovoltaic power grids in China is increasing, and the interference it will cause to the power grid will become more and more intense, and the application environment of the front and rear ends of the inverter will become more and more complex.

Images