Abstract
This paper put forward the inertial control strategy based on the control of charge and discharge of supercapacitor and the trigger angle of H-bridge which integrates photovoltaic (PV) system. The whole cascade H-bridge structure is composed of traditional photovoltaic module, Boost/Buck circuit, supercapacitor (SC), and H-bridge circuit. First, the charging state and the inertial energy power support of the SC are analysed. Then the control strategy of the cascade H-bridge is proposed. To verify the efficiency of the control strategy, a cascade chain consists of 12 H-bridge unit was built in EMTP simulation software. Finally the simulation results prove that the newly developed SC-integrated cascade module can do inertial energy support well, which is important to the coordination between the power system and solar energy.
Highlights
Photovoltaic power fluctuations caused by environmental factor are fairly violent
Those PV stations can only adjust the maximum power of photovoltaic arrays by using the maximum power point tracking (MPPT), but cannot guarantee the maximum power operation of every photovoltaic module [2], resulting in a certain amount of energy waste
In order to make the cascade H-bridge photovoltaic modules have the ability of inertial support and spontaneously responding to the system frequency changes, this paper proposes a virtual synchronous control strategy based on the inertial characteristics of synchronous generators
Summary
Photovoltaic power fluctuations caused by environmental factor are fairly violent. At the same time, the grid inverter’s fast dynamic response and its small inertial energy makes itself lack of the ability of frequency modulation and voltage regulation of power grids. The above research hopes to make the solar photovoltaic power station equivalent to a virtual synchronous machine through the control algorithm of the inverter, so that it has the ability to support the dispatching for frequency modulation and voltage regulation. In this paper we propose a new structure of photovoltaic modules based on cascade H-bridge, and its main contributions are as follows: 1) A kind of chain-cascading topology with inertial energy link is proposed, which is applied to solar photovoltaic power generation and provides the basis of grid-friendly control for solar photovoltaic power generation. 2) The MPPT algorithm of the underlying voltage regulator circuit and the inertial energy control cascade H-bridge photovoltaic module control algorithm are proposed, which realize the grid friendliness.
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