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Photovoltaic off-grid grid-connected power generation integrated control system

A photovoltaic power generation system and control system technology, applied in photovoltaic power generation, system integration technology, AC network circuit, etc., can solve problems such as affecting the service life of batteries, inability to connect the inverter to the grid, reducing output power, etc., so as to prolong the service life. , Reasonable application of electric energy, energy saving effect

Inactive Publication Date: 2018-03-09
XUZHOU NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] With the development of the times, the application of distributed photovoltaic power generation projects has kicked off, and then a variety of solutions have been proposed in the industry, among which the photovoltaic off-grid integrated control system has attracted widespread attention. The integrated control system mainly uses a bidirectional inverter as the system control core, and a photovoltaic grid-connected inverter is added to the load side to realize off-grid integration. The grid-connected inverter follows the mains grid to output electric energy with the same waveform, and at the same time, the bidirectional inverter charges the battery through the internal charging control circuit. When the mains is disconnected, the bidirectional inverter cuts off the connection between the mains and the internal grid The battery supplies power to the load through the bidirectional inverter, and at the same time provides reference power to the grid-connected inverter. The bidirectional inverter adjusts its own output frequency to make the grid-connected inverter in the working or standby state, for example, the bidirectional inverter The standard output frequency is 50Hz. When the voltage of the battery is higher than the set charging cycle voltage, the bidirectional inverter will increase the output voltage frequency, so that the grid-connected inverter will have an island protection effect, and the grid-connected inverter will turn off the output. , when the battery voltage is lower than the floating charge voltage, the frequency will automatically return to the initial value, but the method of controlling the work of the grid-connected inverter by adjusting the output frequency of the bidirectional inverter can only make the grid-connected inverter in the working and standby states , the grid-connected inverter cannot reduce the output power to work, so the grid-connected inverter sometimes works and sometimes stands by, and the voltage of the battery is high and low, which not only affects the service life of the battery, but also causes a waste of energy from the solar panel

Method used

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Examples

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example 1

[0038] Based on step e, implementation and optimization of phase-shifted full-bridge soft switching technology

[0039] In the full-bridge phase-shift soft switching circuit, it is much more difficult to achieve soft switching in the lagging arm than in the super-forearm, because the switching tube of the super-forearm participates in the resonant inductance coupling inductance and the equivalent primary inductance of the secondary side when it is turned on and off. The sum of , can easily meet the charging and discharging energy of the super forearm capacitor. When the lagging arm realizes ZVS, the inductance resonating with the lagging arm capacitance is only the coupling inductance. To realize the ZVS of the lagging arm, the following relationship must be established:

[0040]

[0041] where C 2 =C 4 S respectively 2 and S 4 of parasitic capacitance.

[0042] If there is no clamping inductor L P , at the end of the circulation, L P Will and C S starts to resonat...

example 2

[0046] Based on off-grid system modular power management and control strategy, please refer to image 3

[0047] The on-grid and off-grid dual-mode inverter can automatically adjust each module to switch on or off the power control unit according to different environmental conditions, so as to realize efficient and full utilization of energy. The specific working mode is as follows:

[0048]a) Grid-connected inverter mode. When the PV module is connected to the grid normally, the system works in grid-connected inverter mode. The MPPT controller transmits energy to the downstream inverter link with the maximum power, the grid-connected current and the grid voltage have the same frequency and phase, and the inverter feeds energy to the grid with a unit power factor of 1. When a load is connected, the load is directly connected to the grid through the bypass switching switch, and the load energy is provided by the grid.

[0049] b) Grid-connected charging mode. When the PV m...

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Abstract

The invention discloses a photovoltaic off-grid grid-connected power generation integrated control system comprising the following steps: a, off-grid grid-connected / off-grid power generation system main circuit system design and optimization; b, off-grid grid-connected / off-grid power generation system hardware and software control system; c, high precision maximum power point tracking technology;d, full-bridge model research and controller design; e, phase shift full bridge soft-switching technology realization and optimization; f, off-grid grid-connected system modularization power management and control strategy; g, off-grid photovoltaic power generation system; h, off-grid grid-connected / off-grid power generation system communication module. The system mainly solves the user photovoltaic generating self-usage problems, and improves the user power consumption quality; the design purpose, research resources and realizability are combined; a battery charge-discharge module and an off-grid load port are added on a grid-connected inverter, thus increasing the energy storage function without losing inversion efficiency.

Description

technical field [0001] The invention relates to the technical field of energy power generation, in particular to an integrated control system for photovoltaic off-grid and grid-connected power generation. Background technique [0002] With the development of the times, the application of distributed photovoltaic power generation projects has kicked off, and then a variety of solutions have been proposed in the industry, among which the photovoltaic off-grid integrated control system has attracted widespread attention. The integrated control system mainly uses a bidirectional inverter as the system control core, and a photovoltaic grid-connected inverter is added to the load side to realize off-grid integration. The grid-connected inverter follows the mains grid to output electric energy with the same waveform, and at the same time, the bidirectional inverter charges the battery through the internal charging control circuit. When the mains is disconnected, the bidirectional i...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J13/00H02M1/00
CPCH02J3/385H02J13/0017H02J13/0062H02J13/0075H02M1/00H02M1/0058Y04S10/123Y02B70/10Y02E10/56Y02E40/70Y04S40/124Y04S40/126Y02E60/00
Inventor 聂新明田亚平方婷袁迪
Owner XUZHOU NORMAL UNIVERSITY