Novel three-phase photovoltaic grid-connected inverter system

An inverter, three-phase technology, applied in the field of new three-phase photovoltaic grid-connected inverter system, can solve the problems of low power generation efficiency, low grid-connected voltage, unable to realize grid-connected photovoltaic array, etc. The effect of increasing the voltage on the grid-connected side, improving the utilization rate of light energy and the power generation efficiency of the system

Inactive Publication Date: 2012-12-19
GUANGDONG MINGYANG LONGYUAN POWER ELECTRONICS
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AI-Extracted Technical Summary

Problems solved by technology

[0002] At present, 1MW three-phase photovoltaic power generation system such as image 3 As shown, most of the outputs of two 500kW photovoltaic grid-connected inverters are directly connected in parallel, or as Figure 4 As shown, two 500kW photovoltaic grid-connected inverters are used to realize the parallel connection of two low-voltage windings of a double...
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Method used

Each photovoltaic array DC output as above is connected with DC arrester 10 between corresponding DC circuit breaker 1 input end, is connected with AC arrester 11 between described AC circuit breaker 9 output terminals and grid, prevents Lightning strike, protect device safety.
Embodiment 1, as shown in Figure 1, described photovoltaic array is two, and when the level of output DC voltage is respectively 500V, 700V, each photovoltaic array passes through DC circuit breaker 1, DC EMI filter 2 respectively , BOOST boost circuit 3 to boost the voltage, and controller 15 to perform maximum power tracking control of BOOST boost circuit 3 to boost the voltage to 960V level, and then perform three-phase inversion through the three-phase full-bridge IGBT inverter circuit 5 Transform grid-connected power generation, and the grid-connected voltage can be increased to more than 620V. Through the above structure, two different photovoltaic arrays can be connected to the grid together, which not only expands the maximum power point tracking range, but also improves the DC side voltage and inverter conversion. efficiency.
Embodiment 2, as shown in Figure 2, described photovoltaic array is 3, and when the level of output DC voltage is respectively 500V, 700V, 900V, each photovoltaic array passes through DC circuit breaker 1, DC EMI filter respectively Booster 2, BOOST booster circuit 3 for boosting, and controller 15 for maximum power tracking control of BOOST booster circuit 3, boosting the DC side voltage to 960V level, and then through the three-phase full-bridge IGBT inverter circuit 5 For three-phase inverter grid-connected power generation, the grid-connected voltage can be increased to more than 620V. Through the above structure, the simultaneous grid-connection of three different photovoltaic arrays is realized, which not only expands the maximum power point tracking range, but also improves the DC side voltage. and inverter conversion efficiency.
The size of photovoltaic array output voltage mentioned in the embodiment of the present invention and parameters such as the voltage level that direct current is boosted to 960V by BOOST step-up circuit 3, not as the limitation to protection scope of the present invention, it is just a kind of specific Parameter settings in the examples. What the present invention protects is a topological structure that can independently boost ...
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Abstract

The invention discloses a novel three-phase photovoltaic grid-connected inverter system, wherein the system can be combined to grid after outputting the direct current to different photovoltaic arrays to independently boost; the system has good compatibility to the accessed photovoltaic array; the system boosts the corresponding photovoltaic array respectively through the BOOST circuit and tracks and controls the maximum power point of the BOOST circuit through a controller, so that the tracking range of the maximum power point is enlarged, and the direct current side voltage and the inverter conversion efficiency are improved; the system can be combined and connected with different photovoltaic arrays to achieve combination to the grid through single inverter, so the novel three-phase photovoltaic grid-connected inverter system saves cost and improves the voltage of the grid-connected side, and meanwhile, meets different photovoltaic array combination ways and different environmental requirements and improves the light energy utilization rate and the system generating efficiency.

Application Domain

Ac-dc conversionDc-dc conversion +3

Technology Topic

Three-phaseGrid connected inverter +4

Image

  • Novel three-phase photovoltaic grid-connected inverter system
  • Novel three-phase photovoltaic grid-connected inverter system
  • Novel three-phase photovoltaic grid-connected inverter system

Examples

  • Experimental program(2)

Example Embodiment

[0028] Example 1, such as figure 1 As shown, there are two photovoltaic arrays, and when the output DC voltage levels are 500V and 700V respectively, each photovoltaic array is boosted by a DC circuit breaker 1, a DC EMI filter 2, and a BOOST boost circuit 3. And the controller 15 perform the maximum power tracking control of the BOOST boost circuit 3, boost the voltage to 960V, and then use the three-phase full-bridge IGBT inverter circuit 5 to perform three-phase inverter and grid-connected power generation, and the grid-connected voltage can be increased Above 620V, through the above structure, two different photovoltaic arrays can be connected to the grid together, which not only expands the maximum power point tracking range, but also improves the DC side voltage and inverter conversion efficiency.

Example Embodiment

[0029] Example 2, such as figure 2 As shown, there are three photovoltaic arrays, and when the output DC voltage levels are 500V, 700V, 900V, each photovoltaic array is boosted by a DC circuit breaker 1, a DC EMI filter 2, and a BOOST boost circuit 3. The controller 15 performs the maximum power tracking control of the BOOST boost circuit 3, boosts the DC side voltage to 960V, and then performs three-phase inverter grid-connected power generation through the three-phase full-bridge IGBT inverter circuit 5, and The grid voltage can be increased to above 620V. Through the above structure, three different photovoltaic arrays can be connected to the grid together, which not only expands the maximum power point tracking range, but also improves the DC side voltage and inverter conversion efficiency.
[0030] The sine filter 6 described in the above two embodiments uses an LCL sine filter to eliminate harmonics to obtain alternating current with the same frequency as the power grid.
[0031] The specific working principles of the present invention and the above two embodiments are as follows: the DC power converted by the photovoltaic array is integrated by the DC distribution box and then leads to each group of positive and negative DC output lines, and is input to the DC EMI filter 2 through the DC circuit breaker 1 for low pass. Filtering, eliminating the high frequency interference signal of DC, and realizing the protection of the DC distribution terminal, and then boosting each group of input DC voltage through the BOOST booster circuit 3, at the same time, the current and voltage detection module 12 detects the DC side voltage and current in real time , AC side voltage and current, through the power calculation of the controller 15 to complete the maximum power tracking of each BOOST booster circuit 3, the stable DC power is absorbed by the DC support capacitor 4 to absorb the ripple current and then sent to the three-phase full bridge IGBT Inverter circuit 5, and the three-phase full-bridge IGBT inverter circuit 5 is driven by the controller 15, and then the alternating current output by the three-phase full-bridge IGBT inverter circuit 5 is eliminated by the sinusoidal filter 6 to get the power grid The AC power of the same frequency is merged into the power grid after eliminating high frequency interference through the AC EMI filter 8.
[0032] In general, the output DC voltage levels of photovoltaic arrays on the market are as described above. The two embodiments described above have met most practical applications. If other photovoltaic arrays are to be connected in practice, those skilled in the art The need can be achieved based on the above technical enlightenment.
[0033] The parameters such as the output voltage of the photovoltaic array and the boosting of the DC power to the voltage level of 960V through the BOOST boost circuit 3 mentioned in the embodiment of the present invention are not as a limitation to the protection scope of the present invention, but are only a specific embodiment. Parameter setting. The invention protects a topological structure that can independently boost the output DC power of different photovoltaic arrays and then connect to the grid for power generation, which meets the combination of different photovoltaic arrays and has good compatibility. By using multiple sets of BOOST boost circuits 3 Multiple sets of different photovoltaic arrays are boosted, and the maximum power point tracking control of each BOOST booster circuit 3 is performed through the controller 15, which expands the maximum power point tracking range and greatly increases the DC side voltage, and then passes through an inverter Inverter grid-connected power generation saves costs and increases the grid-connected side voltage. At the same time, it satisfies different photovoltaic array combinations and different environmental requirements, and improves solar energy utilization and system power generation efficiency.

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