Multi-way MPPT photovoltaic inversion system

Abstract

The invention relates to a multi-way MPPT photovoltaic inversion system which is technically characterized in that an inverter main circuit comprises a plurality of independent photovoltaic inversion units; a plurality of photovoltaic modules are connected with the corresponding photovoltaic inversion units via photovoltaic inversion unit direct current contactors and EMI (Electro-Magnetic Interference) filter circuits respectively; the photovoltaic inversion units are connected with a three-phrase power grid via an LCL (Lower Control Limit) filter circuit; the inverter control circuit is formed by connecting a main station control system and a plurality of slave station control systems; each photovoltaic inversion unit acquires respective alternating current inlet wire current, direct current voltage and direct current; and power grid voltage is acquired by the main station control system of the inverter control circuit and transmitted to the slave station control systems for common use at high speed. The system employs a high-speed communication manner between a main station and a slave station to achieve an inversion output carrier function, and reduces common mode voltage between inverters, the stability and reliability of the system are improved, common mode current through a PV (Photovoltaic) array is reduced, and the service life of a battery board is prolonged.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic inverters, in particular to a multi-channel MPPT photovoltaic inverter system. Background technique [0002] A photovoltaic power generation system usually consists of a battery panel array and a power conversion (inverter) part, and usually requires a low-frequency transformer to be placed between the inverter and the grid for electrical isolation between the grid and the PV array. Non-isolated inverters are more and more valued by manufacturers due to their advantages of high efficiency, low cost, and small size. However, if the transformer is removed, the PV array will be electrically connected to the grid, and the common-mode current will increase significantly, bringing Potential safety hazards, and will also have adverse effects on the battery board. At present, the use of multi-MPPT (Maximum Power Point Tracking, maximum power point tracking) to increase the power generation of invert...

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Problems solved by technology

The literature "Transformerless single-phase multilevel-based photovoltaic inverter" establishes a common-mode equivalent model for a single-phase bridge-type three-level grid-connected inverter, and draws the conclusion that the common-mode voltage is constant, thereby reducing the common-mode current. However, the The conclusion does not hold in the three-phase system

The literature "Research on Common-mode Current Suppression Technology of NPC Three-level Grid-connected Inverter" analyzes the common-mode characteristics of three-level photovoltaic inverters, and proposes compensation measures to enhance the common-mode suppression performance of three-level photovoltaic inverters, but , this method has poor practicability and is difficult to use in engineering practice

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