A bus voltage control method, controller and photovoltaic energy storage conversion system

Abstract

The bus voltage control method, controller and photovoltaic energy storage conversion system provided by the present invention are applied in the technical field of photovoltaic power generation. The method first judges whether the photovoltaic energy storage conversion system is connected to a photovoltaic system under the condition that the preset bus voltage control condition is met. If the photovoltaic module is connected to the photovoltaic energy storage conversion system, the energy storage battery is controlled to stop working, and the DC bus voltage is stabilized by the photovoltaic module; if the photovoltaic module is not connected to the photovoltaic energy storage conversion system, the preset parameter threshold is the target value Stop the charging process of the energy storage battery. Since the preset parameter threshold is given based on the sampling error of the photovoltaic energy storage conversion system, when the charging process of the energy storage battery is stopped according to the preset parameter threshold, the charging current of the energy storage battery can be guaranteed If it is greater than or equal to 0, there will be no negative value, so as to avoid the continuous charging of the energy storage battery to the DC bus, and will not cause the problem of bus voltage rise, and improve the stability of the photovoltaic energy storage conversion system.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a bus voltage control method, a controller and a photovoltaic energy storage conversion system. Background technique [0002] Photovoltaic energy storage conversion system is a distribution sub-system connected with distributed power supply, which can operate normally independently and maintain the power supply of all or some important electrical equipment. Such as figure 1 and figure 2 As shown, there are two output modes of DC output and AC output in the practical application of the photovoltaic energy storage conversion system. connected to the public grid through the DC bus; when the AC output mode is adopted, the photovoltaic module and the energy storage battery are first connected to the DC bus through their corresponding DC / DC converters, and then connected to the DC / AC converter through the DC bus On the DC side, it is finally input to the publi...

AI Technical Summary

Problems solved by technology

[0004] However, in practical applications, due to the existence of current sampling errors, such a situation often occurs: the charging current of the energy storage battery has actually dropped to zero, but the current sampling data is greater than zero. In order to stop charging the energy storage battery, The controller will continue to reduce the current of the DC / DC converter, causing the current flowing through the DC / DC converter to become negative. For the energy storage battery, the DC bus is actually discharged with a small current. The load on the output side of the bus is zero, and the energy storage battery will continuously charge up the voltage of the DC bus, eventually triggering the overvoltage protection of the DC bus by mistake

Images