Bus voltage control method, controller and photovoltaic energy storage conversion system

Abstract

The invention provides a bus voltage control method, a controller and a photovoltaic energy storage conversion system, belonging to the technical field of photovoltaic power generation. The method comprises the following steps: firstly judging whether a photovoltaic module is connected with a photovoltaic energy storage conversion system or not under the condition that a preset bus voltage controlcondition is me; if the photovoltaic module is connected with the photovoltaic energy storage conversion system, controlling an energy storage battery to stop working, and stabilizing a direct-current bus voltage by the photovoltaic module; and if the photovoltaic module is not connected to the photovoltaic energy storage conversion system, stopping the charging process of the energy storage battery by taking a preset parameter threshold as a target value. Since the preset parameter threshold value is given based on the sampling error of the photovoltaic energy storage conversion system, whenthe charging process of the energy storage battery is stopped according to the preset parameter threshold, it can be ensured that the charging current of the energy storage battery is greater than orequal to 0, and no negative value condition occurs; and thus, the energy storage battery is prevented from continuously charging a DC bus, the problem of bus voltage rise is avoided, and the stability of the photovoltaic energy storage conversion system is improved.

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

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