T-type three-level inverter finite set model prediction control method and system

A three-level inverter, finite set model technology, applied in photovoltaic power generation, electrical components, single-grid parallel feeding arrangement, etc., can solve the problems of occupying a large storage space, not using it alone, damaging devices, etc.

Inactive Publication Date: 2015-09-30
SHENYANG POLYTECHNIC UNIV
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Problems solved by technology

In a three-level grid-connected inverter, the unbalanced midpoint potential on the DC side will lead to an increase in the maximum reverse voltage of the switch tube, and even damage the device in severe cases, greatly reducing system reliability. In addition, when the midpoint potential is unbalanced , the inverter output voltage contains low-order harmonics, which directly affect the output performance of the grid-connected inverter, so the midpoint potential of the DC side must be controlled
In order to keep the midpoint voltage balanced, scholars have proposed modulation strategies, such as sinusoidal PWM control, space

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  • T-type three-level inverter finite set model prediction control method and system
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  • T-type three-level inverter finite set model prediction control method and system

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Embodiment Construction

[0092] The present invention adopts a finite set model predictive controller based on Lyapunov function to control the T-type three-level photovoltaic grid-connected inverter, and the summary includes the following steps:

[0093] (1) System initialization;

[0094] (2) Detect the load current of the inverter;

[0095] (3) Coordinate transformation: transform the abc coordinate system to the αβ coordinate system;

[0096] (4) According to the three-phase voltage and current in the αβ coordinate system, the current and voltage prediction values ​​of the three-level grid-connected inverter under 27 switching states are obtained through the prediction current and voltage formulas;

[0097] (5) Value function initialization;

[0098](6) Cycle judgment;

[0099] (7) Calculate value function value;

[0100] (8) Compare the value function with the initialization value, and select the switch state that minimizes the objective function;

[0101] (9) Apply the new switch state to d...

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Abstract

The invention belongs to the technical field of photovoltaic grid-connected inverters, and particularly relates to a T-type three-level inverter finite set model prediction control method and system, which have the advantages that the delay time is shortened when rapid dynamic response is ensured and a nonlinear system is introduced. The prediction control method comprises the following steps: the three-phase output of an inverter is grid-connected with a power grid through inductance and resistance loads under the condition that an equation is met, wherein the equation, R and L are respectively an resistance load and an inductance load; u refers to the voltage vector generated by the inverter, e refers to the voltage vector of the power grid, and I refers to current vectors of the loads; a voltage uaN, a voltage ubN and a voltage ucN of output phases of the inverter are converted through Clark, and an abc three-phase static coordinate system is converted into an alpha-phase and a beta-phase static coordinate system.

Description

technical field [0001] The invention belongs to the field of photovoltaic grid-connected inverter technology, and in particular relates to a finite set model predictive control method and system for a T-type three-level inverter. Background technique [0002] Three-level inverter technology is mainly used in high-voltage and high-power occasions. Photovoltaic grid-connected power generation is one of the important applications of three-level technology. Photovoltaic grid-connected power generation combines unstable photovoltaic panels and passes through multi-level power electronics. The converters are combined, and finally output a constant frequency AC voltage and run on the grid. In photovoltaic grid-connected power generation, the inverter plays a key role. With the continuous development of switching devices, the topology, modulation mode and control strategy of the inverter are also continuously developed, and the control theory is applied in the control of the invert...

Claims

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Application Information

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IPC IPC(8): H02M7/483H02J3/38
CPCY02E10/56
Inventor 王丽梅王美龄
Owner SHENYANG POLYTECHNIC UNIV
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