Photovoltaic grid-connected inverter electronic anti-islanding testing device

Abstract

A photovoltaic grid-connected inverter electronic anti-islanding testing device comprises a direct current side (4), an input side (3), an output side (5) and a control system. The electronic anti-islanding testing device is connected in series between a photovoltaic grid-connected inverter (2) and a large power grid (6). The electronic anti-islanding testing device absorbs energy stable voltage at the direct current side for a power grid side, the input side inversely forms a voltage source; the grid-connected inverter tracks voltage output in real time after detecting voltage source with stable frequency, the grid-connected inverter power flow flows in the electronic anti-islanding input side, and the output side feeds the energy back to the power grid through a four-quadrant control strategy. Through adoption of the real-time control technology, the photovoltaic grid-connected inverter electronic anti-islanding testing device can detect active power and reactive power output by the grid-connected inverter in real time and calculate the resistance, inductance and capacitance of a load required being simulated. When the anti-islanding test, the photovoltaic grid-connected inverter electronic anti-islanding testing device can allow the anti-islanding protection testing experiment not to be restrained by field conditions according to an anti-islanding protection testing experiment of various conditions such as load matching and the like required in the national standard.

Description

technical field [0001] The invention relates to an electronic anti-islanding test device for a photovoltaic grid-connected inverter, which belongs to the technical field of photovoltaic power generation. Background technique [0002] In recent years, distributed new energy generation has maintained a continuous growth trend due to its economy and effectiveness, and its access to the distribution network has also brought a series of problems to the power grid, among which "island" is currently the most widely studied one of the subjects. Once islanding occurs, it may cause problems such as personal safety, economic benefits, and power quality. According to the standard, the inverter should be integrated into the 10KV and below voltage level distribution network and should have the protection function of anti-islanding effect. If the power supply of the grid into which the inverter is integrated is interrupted, the inverter shall stop supplying power to the grid within 2s an...

AI Technical Summary

Problems solved by technology

Among them, the passive island detection method judges the island based on detecting whether the parameters such as voltage, frequency, and harmonic content exceed the limit. Phase angle jump detection method, harmonic detection method, etc. The main advantage of the passive detection method is that it will not affect the power quality, but there is a large detection blind area; the active detection method is the amplitude and frequency of the inverter current. Inject disturbances such as , phase, etc. When islanding occurs, the voltage parameters of the common point will change to determine the islanding state. Its main advantage is to reduce or even eliminate blind spots, but it will cause deterioration of the power quality of the power grid and even affect the stability of the power grid. characteristics; small disturbances are generated for the photovoltaic inverter, and a certain parameter of the power grid changes, including frequency drift method, reactive power change method, harmonic injection method

[0004] At present, the anti-islanding protection of photovoltaic grid-connected inverters mainly uses adjustable RLC parallel simulation load laboratory tests. This test method is not only complicated in the test process, but also under harsh test conditions. With the development of power electronics technology, PWM control technology is becoming more and more mature. , not only accurately control the rectification and inverter to realize the voltage source and current source, but also realize the two-way transmission of energy

[0005] At present, the anti-islanding protection of photovoltaic grid-connected inverters mainly uses adjustable RLC parallel simulation load laboratory tests. This test method is not only complicated in the test process, but also under harsh test conditions.

[0006] The traditional RLC load anti-islanding protection test platform is mainly composed of DC source, photovoltaic grid-connected inverter, RLC test unit, digital oscilloscope, and large power grid. The traditional experimental method can adjust the RLC parallel load to simulate the island load, and adjust the RLC load through the switch K2 , adjust the value of resistance, inductance, and capacitance, and monitor the input power of manually adjusted RLC load through a digital oscilloscope to be close to the grid-connected power of the photovoltaic grid-connected inverter. Difficult to achieve accurate power matching

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