Resonance Suppression Method of Single-phase lcl Grid-connected Inverter Based on Output Grid-side Current Estimation

A network-side current and resonance suppression technology, which is applied to the AC network to reduce harmonics/ripples, harmonic reduction devices, single-network parallel feeding arrangements, etc., to improve stability, save costs, and overcome energy loss problems Effect

Active Publication Date: 2018-11-02
NANCHANG UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to provide a single-phase LCL grid-connected inverter resonance suppression method based on output grid side current estimation to solve the problem of single-phase LCL grid-connected inverter control in distributed grid-connected power generation. Inverter resonance problem caused by the third-order characteristics of the LCL filter itself

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  • Resonance Suppression Method of Single-phase lcl Grid-connected Inverter Based on Output Grid-side Current Estimation
  • Resonance Suppression Method of Single-phase lcl Grid-connected Inverter Based on Output Grid-side Current Estimation
  • Resonance Suppression Method of Single-phase lcl Grid-connected Inverter Based on Output Grid-side Current Estimation

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[0018] The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and working principle.

[0019] figure 1 It is a system structure diagram of the present invention, the main circuit structure outside the dotted line frame, DC is a direct current voltage source, AC is a power grid, and G P is a single-phase inverter, inverter side inductance L, grid side inductance L g and capacitor C together form the LCL filter, the terminal is the voltage measurement terminal, For the current measurement terminal. Inside the dashed box is the control structure, in which the Est module is the grid-side current estimation method provided by the present invention, the purpose of which is to filter out the grid-side current measurement value i g Harmonics of the resonance point, get the new value i′ g ; The SPLL module is a software phase-locked loop, the purpose is to obtain the unit sine function sinθ with the sa...

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Abstract

According to a single-phase LCL-type grid-connected inverter resonance suppression method based on output-network side current estimation, through utilization of characteristics that an LCL filter is similar to the L-type filter in terms of a low-intermediate frequency band and the frequency characteristic of the L-type filter has no resonance peak, integration is carried out by an output of a controller Gc (s) (the gain of an integrator is a reciprocal of a total inductance value of the LCL filter) to obtain an estimated value of the network side current; at the same time, an observation compensator is introduced and a network side current measurement value is taken as a reference input. The estimated value is corrected and the estimated value is used to track the measurement value to achieve the purpose of filtering the measured value of the network side current. The estimated value is the measurement value of filtering.

Description

technical field [0001] The invention relates to a method for suppressing resonance of a single-phase LCL type grid-connected inverter based on output grid side current estimation, and belongs to the field of inverter circuit control. Background technique [0002] The serious situation of energy shortage and environmental pollution in today's world has attracted people's attention. Photovoltaic power generation technology has attracted more and more attention because of its clean and renewable energy. Among them, distributed grid-connected power generation is one of the main utilization methods of photovoltaic power generation technology. Since photovoltaic cells output direct current and cannot be directly connected to the grid, inverter technology is required to convert the direct current output by photovoltaic cells into alternating current acceptable to the grid. In order to suppress the harmonics generated by the switching operation of power devices, it is necessary to a...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/01
CPCH02J3/01H02J3/38Y02E40/40
Inventor 万晓凤聂晓艺丁小华刘志宇余运俊刘琦杜利平
Owner NANCHANG UNIV
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