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Method for circulating current restraining of parallel system of dual grid-connected inverters based on zero voltage vector feedforward control

A circulating current suppression and feedforward control technology, applied in the direction of converting AC power input to DC power output, electrical components, and single-network parallel feeding arrangement, etc., can solve problems such as slow dynamic response, and achieve high dynamic response speed and control effect. Effect

Active Publication Date: 2012-08-08
SIEMENS ELECTRICAL DRIVES
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Problems solved by technology

[0004] The present invention aims to solve the problem of slow dynamic response when the given currents of the two inverters change in the existing system circulating current suppression method, and provides a dual-grid-connected inverter based on voltage zero-vector feedforward control Circulating Current Suppression Method for Parallel System

Method used

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  • Method for circulating current restraining of parallel system of dual grid-connected inverters based on zero voltage vector feedforward control
  • Method for circulating current restraining of parallel system of dual grid-connected inverters based on zero voltage vector feedforward control
  • Method for circulating current restraining of parallel system of dual grid-connected inverters based on zero voltage vector feedforward control

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specific Embodiment approach 1

[0034] Specific implementation mode one: the following combination Figure 1 to Figure 10 This embodiment will be described. The method for suppressing circulation in a parallel system of dual grid-connected inverters based on voltage zero-vector feedforward control described in this embodiment, the dual grid-connected inverters share an AC bus and a common DC bus, and the circulating current suppression The method is based on the PI control method of the inverter parallel system,

[0035] The circulating current suppression method is to control the circulating current of an inverter in the double grid-connected inverter, and it includes the following steps:

[0036] Step 1: To the zero-sequence current i of the second inverter 2 z2 to sample;

[0037] Step 2: Using the zero sequence current controller 3 to control the zero sequence current i of the second inverter 2 z2 and the given zero-sequence current i of the second inverter 2 z2_ref Perform PI adjustment, and divide ...

specific Embodiment approach 2

[0040] Specific implementation mode two: the following combination figure 1 Describe this embodiment, this embodiment is a further description of Embodiment 1, the zero-sequence current i of the second inverter 2 z2 for:

[0041] i z2 = i a2 + i b2 + i c2 ,

[0042] where i a2 is the a-phase current of the second inverter 2, i b2 is the b-phase current of the second inverter 2, i c2 is the c-phase current of the second inverter 2 .

specific Embodiment approach 3

[0043] Specific implementation mode three: the following combination Figure 1 to Figure 10 Describe this embodiment, this embodiment is a further description of Embodiment 2, the correction value y of the second inverter zero vector output by the zero-sequence current controller 3 2 for:

[0044] y 2 = ( K p _ z + K i _ z s ) · ( i z 2 _ ref - i z 2 ) - Δ d ...

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Abstract

A method for circulating current restraining of a parallel system of dual grid-connected inverters based on zero voltage vector feedforward control belongs to the technical field of circulating current restraining of the parallel system of dual grid-connected inverters. The method solves the problem of existing system circulating current restraining methods that the dynamic response is slow when given current of two inverters changes. The dual grid-connected inverters share an alternating current bus and a direct current bus, and the method for circulating current restraining is based on the method for controlling proportional integral (PI) of parallel systems of inverters, introduces feedforward control of the difference between a non-zero vector and a duty ratio in space vector pulse width modulation (SVPWM) of two inverters, has high dynamic response speed and good control effect and is applicable to restraining the circulating current to a small range when the given current of one inverter is different from that of the other inverter. The method is applicable to parallel structures of three-phase grid-connected inverters without neutral lines.

Description

technical field [0001] The invention relates to a method for suppressing circulation in a parallel system of double grid-connected inverters based on voltage zero-vector feedforward control, and belongs to the technical field of circulation suppression for associated systems of double-grid inverters. Background technique [0002] In a distributed energy generation system, in order to increase the system capacity and improve system reliability, multiple inverters are often connected in parallel. This parallel structure not only increases the capacity, but also provides a path for the circulation. The circulating current will have adverse effects on the system, such as distorting the waveform, increasing the system loss, reducing the system efficiency, and even exceeding the power level of the equipment. Therefore, it is necessary to suppress the circulating current when designing the controller of the system. [0003] There are two main ways to suppress the circulating curren...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/537H02M7/5387H02J3/38
Inventor 张学广徐殿国王瑞刘鑫龙张文杰陈佳明
Owner SIEMENS ELECTRICAL DRIVES
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