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Interference suppression method of LCL filter grid-connected inverter

A technology of interference suppression and filter, which is applied in the field of interference suppression of LCL filter grid-connected inverters, can solve problems such as uncertain grid parameters, system instability, and increased inverter injection grid current distortion rate, etc., to achieve The effect of good robustness

Active Publication Date: 2019-10-11
HARBIN INST OF TECH +1
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  • Application Information

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Problems solved by technology

[0005] In order to solve the problem that a small disturbance of the grid voltage will greatly increase the distortion rate of the current injected into the grid by the inverter, and cause system instability and uncertain parameters of the grid, the invention provides an LCL filter grid-connected inverter Interference suppression method, the present invention provides the following technical solutions:

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  • Interference suppression method of LCL filter grid-connected inverter
  • Interference suppression method of LCL filter grid-connected inverter
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specific Embodiment 1

[0071] according to figure 1 Shown block diagram, the present invention provides a kind of interference suppression method of LCL filter grid-connected inverter, comprises the following steps:

[0072] Step 1: Convert the LCL filter to a first-order system, and design the first-order ADAR system model of the LCL filter;

[0073] Step 2: Simplify the first-order ADAR system model of the LCL filter, the input signal passes through the tracking differentiator, the transient state is listed by the tracking differentiator, and the derivatives of each order of the input signal are calculated;

[0074] Step 3: Extend the state observer, calculate the equation of the linear extended state observer, estimate the state variable and total disturbance through the second-order linear extended state observer, and integrate the disturbance with self-resonance;

[0075] Step 4: Carry out feedback control on the state error, and combine the reference signal of the future tracking differentiat...

specific Embodiment 2

[0127] Firstly, the LCL filter is approximated as a first-order system, and on this basis, the controller and the system model of the approximate LCL filter are designed as follows:

[0128]

[0129] In the formula: f(t,y,w) represents the estimated total disturbance that needs to be mitigated, including external disturbance w and internal dynamics, t represents time, y represents grid current, u is the reference input of the inverter, b is the system parameter .

[0130] The input signal passes through the link of the tracking differentiator to calculate the derivatives of each order of the input signal. For a first-order system, the output y is defined as the first state x1; the total disturbance f is defined as the extended state x2. Assuming that f is differentiable, adding dots represents differentiation, and the system model is expressed in the state space of the vector state x as follows:

[0131]

[0132] In the formula:

[0133] C=(1 0)

[0134] Among them...

specific Embodiment 3

[0166] The difference between the output signal and the signal of the input signal through the tracking differentiator through the linear expansion state observer is obtained, and it is controlled. This embodiment is a method suitable for implementing robust current control of an inverter using an LCL filter in a power grid with various disturbances, so as to achieve active suppression of external and internal disturbances. Due to grid loads or grid faults, etc., there will be disturbances in the grid, which will cause resonance of the LCL filter and cause system instability. This requires that the current control can still have high-quality grid-connected current in the presence of disturbances. Specific as figure 1 , it can be seen that the control mainly includes two control loops. The inner loop, called the disturbance suppression loop, is responsible for compensating the total disturbance; the outer loop, called the feedback control loop, realizes the required signal th...

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Abstract

The invention discloses an interference suppression method of an LCL filter grid-connected inverter. The interference suppression method comprises the following steps: converting an LCL filter into afirst-order system, and designing a first-order self anti-interference system model of the LCL filter; simplifying the first-order self anti-interference system model, listing transient states of input signals by a tracking differentiator, and calculating each order of differential coefficients of input signals; extending a state observer, calculating an equation of the linearly extended state observer, estimating state variables and total disturbance through a second-order linearly extended state observer, and integrating disturbance with resonance oscillation; carrying out feedback control on state errors, and combining a reference signal of the tracking differentiator with an output differential signal of the extended state observer to generate an intermediate control voltage signal; selecting observer gain so that a characteristic value of the observer is in a stable state, designing an independent first-order linear controller for each current component, and suppressing external interference and internal interference.

Description

technical field [0001] The invention relates to the technical field of LCL filters, and relates to an interference suppression method for grid-connected inverters with LCL filters. Background technique [0002] In recent years, the global energy shortage and environmental pollution problems have become increasingly serious. In order to solve the energy crisis and protect the environment on which human beings live, finding new energy has become the primary issue now. Such as solar energy, wind energy, tidal energy, etc. are all renewable clean energy. Distributed power generation is being used more and more widely. As an important form of renewable energy utilization, these can be divided into off-grid power generation and grid-connected power generation systems according to different applications. The off-grid system stores the electric energy converted from solar energy in storage battery, and then supply the user equipment through the controller. The grid-connected power...

Claims

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Application Information

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IPC IPC(8): H02J3/01H02J3/38H02M1/12
CPCH02J3/01H02J3/38H02M1/12H02J2203/20Y02E40/40
Inventor 武健刘子栋张利刘同徐殿国
Owner HARBIN INST OF TECH
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