A microgrid based on photovoltaic power generation

Abstract

The invention discloses a microgrid based on photovoltaic power generation, comprising a DC-DC converter 1 whose input end is connected to a photovoltaic module, and the output end of the DC-DC converter 1 is sequentially connected to a multifunctional grid-connected inverter and a circuit breaker S1, circuit breaker S2, distribution network, the DC bus between the DC-DC converter 1 and the multi-functional grid-connected inverter is connected with an energy storage system composed of a bidirectional DC-DC converter 2 and an energy storage battery connected in series A branch circuit, a branch circuit with a DC load is connected to the DC bus between the energy storage branch circuit and the multi-functional grid-connected inverter, and a branch circuit with an AC load is connected between the circuit breaker S1 and the circuit breaker S2; The multifunctional grid-connected inverter described above adopts a double closed-loop feedback control system of DC side voltage and AC side current. Collect the reactive power in the AC load and the instantaneous power emitted by the photovoltaic module, command the inner loop of the current, and actively adjust the active and reactive power of the grid access point, which is conducive to the stability of the grid and the economical power consumption of users.

Description

technical field [0001] The invention relates to the technical field of micro-grids, in particular to a micro-grid based on photovoltaic power generation. Background technique [0002] Solar energy has the advantages of non-pollution, wide distribution, large reserves and renewable. At present, solar power generation is mainly divided into off-grid and grid-connected power generation methods. The grid-connected photovoltaic power generation system consists of photovoltaic modules, grid-connected inverters and grid-connected switches connected to the grid side. The photovoltaic modules convert solar energy into DC power and connect it to the DC side of the grid-connected inverter. The double closed-loop control of the DC side voltage grid side current converts the DC side power into AC power and feeds it into the grid. The power generated by the photovoltaic module is affected by conditions such as light, ambient temperature and humidity, and its output power has strong random...

AI Technical Summary

Problems solved by technology

The grid-connected photovoltaic power generation system consists of photovoltaic modules, grid-connected inverters and grid-connected switches connected to the grid side. The photovoltaic modules convert solar energy into DC power and connect it to the DC side of the grid-connected inverter. The double closed-loop control of the DC side voltage grid side current converts the DC side power into AC power and feeds it into the grid. The power generated by the photovoltaic module is affected by conditions such as light, ambient temperature and humidity, and its output power has strong randomness and Volatility, while photovoltaic grid-connected inverters usually have a maximum power tracking (MPPT) link, the energy fed to the grid by the inverter also has large random and fluctuating characteristics, which can be equivalent to grid-connected inverters As an uncontrollable current source, when a large number of photovoltaic distributed power sources are connected to the grid, it will have a negative impact on the operation and control of the grid

At present, the norms and standards related to the grid-connected operation of distributed power generation have adopted more restrictions on distributed power generation to reduce the impact on the public power grid, which also limits the full play of the efficiency of distributed photovoltaic power generation.

[0003] The photovoltaic system is introduced into the battery energy storage link to form a photovoltaic storage system. The system charges the battery with the DC power generated by the photovoltaic module through the bidirectional DC-DC converter, and meets the basic power demand of the user's AC load. The basic energy management idea is as follows: : First meet the load of the local AC load and maintain the safe charging state of the battery, and then connect the remaining power to the grid to minimize the impact of photovoltaics on the grid. The charging and discharging status of the battery and the working current can be adjusted according to the grid status. The control method of similar photovoltaic inverters is still limited to the mode of passively converting photovoltaic energy into AC power and feeding it into the grid, and cannot actively adjust the active and reactive power of the grid access point, which reduces the flexible access of photovoltaic grid-connected systems. The capacity of the grid also restricts the ability of the grid to accommodate distributed generation systems

Images