Three-phase photovoltaic inverter relay fault detection method
A relay fault and photovoltaic inverter technology is applied in the field of three-phase photovoltaic inverter relay fault detection, which can solve problems such as exceeding the judgment range, non-maintenance cost, poor contact, etc., and achieve the effect of simplifying the judgment logic and reducing the amount of calculation.
Active Publication Date: 2021-06-15
苏州海鹏科技有限公司
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Problems solved by technology
It is generally believed that the three phases of the power grid are independent, but when the photovoltaic inverter is used in some remote rural areas, the neutral point N is in poor contact with the ground point PE, and there is a large voltage between the N point and
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[0033] see figure 1 , figure 1 It is a structural schematic diagram of the three-phase photovoltaic inverter relay fault detection method described in the present invention, as figure 1 As shown, the three-phase photovoltaic inverter relay of the present invention includes an inverter bridge arm side relay 1 and a grid side relay 2, and the three-phase inverter voltages 11 corresponding to the inverter bridge arm side relay 1 are respectively U_Inv_R, U_Inv_S and U_Inv_T, the three-phase grid voltages 21 corresponding to the grid side relay 2 are U_Grid_R, U_Grid_S and U_Grid_T respectively.
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The invention discloses a three-phase photovoltaic inverter relay fault detection method, which comprises the following steps of: sampling current power grid voltage and inversion voltage, carrying out Clark conversion and calculating effective values of alpha and beta components, disconnecting an inversion bridge arm side relay and a power grid side relay, setting a threshold value T, respectively judging whether the effective values of the alpha and beta components of the inversion voltage exceed T or not, and if so, indicating that the power grid side relay is adhered; closing an inverter bridge arm side relay, outputting an open-loop voltage by an inverter bridge, respectively judging whether the difference between the effective values of the alpha and beta components of the power grid voltage and the inverter voltage exceeds T or not, and if so, indicating that the inverter bridge arm side relay is possibly damaged; and opening the inverter bridge arm side relay, closing the power grid side relay, respectively judging whether the difference between the effective values of the alpha and beta components of the power grid and the inverter voltage exceeds T, and if so, indicating that the power grid side relay is not completely closed. Zero-sequence components between voltages are eliminated, positive and negative sequence components of the voltages do not need to be separated, and judgment logic is simplified.
Description
technical field [0001] The invention relates to the field of relay fault detection, in particular to a three-phase photovoltaic inverter relay fault detection method. Background technique [0002] When the photovoltaic inverter fails, the relay on the bridge arm side is generally closed first, and the open-loop voltage is generated through the inverter bridge, and the open-loop voltage generated by sampling is used to judge whether the bridge arm side relay is reliably closed. It is generally believed that the three phases of the power grid are independent, but when the photovoltaic inverter is used in some remote rural areas, the neutral point N is in poor contact with the ground point PE, and there is a large voltage between the N point and the PE point. When the relay judges, the sampled open-loop voltage will superimpose the voltage component between N and PE, which exceeds the normal judgment range, thus misjudging it as a relay failure and bringing unnecessary maintena...
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CPCG01R31/327
Inventor 邓小兵
Owner 苏州海鹏科技有限公司
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