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A Control Method for Parallel Power Sharing of Multiple Inverters in Island Microgrid

A multi-inverter, micro-grid technology, applied in the direction of single-grid parallel feeding arrangement, etc., can solve problems such as the adverse effects of the rapid response speed of the system, the large amount of program calculation, and the complex implementation process.

Inactive Publication Date: 2017-03-08
STATE GRID CORP OF CHINA +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this patent needs to perform fast Fourier transform FFT on the instantaneous active power and instantaneous reactive power, and detect the power of each characteristic subharmonic by frequency division, and then need to calculate and synthesize the harmonic reference voltage for each characteristic subharmonic separately, Such a specific implementation process is too complicated, and the calculation amount of the program is relatively large, which will have a negative impact on the rapid response speed of the system.
[0010] To sum up, the prior art has not solved the problem of inverter power sharing control in low-voltage microgrids due to actual complex factors such as harmonic power, inconsistency of feeder impedance, and inconsistency of inverter rated capacity. technical challenge

Method used

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  • A Control Method for Parallel Power Sharing of Multiple Inverters in Island Microgrid
  • A Control Method for Parallel Power Sharing of Multiple Inverters in Island Microgrid
  • A Control Method for Parallel Power Sharing of Multiple Inverters in Island Microgrid

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Embodiment 1

[0084] A control method for parallel power sharing control of multiple inverters in an island microgrid, the method is applicable to a control system for parallel power sharing of multiple inverters in an island microgrid, and the control system for parallel power sharing of multiple inverters in an island microgrid includes Several parallel inverters, common busbars, linear and non-linear loads, and centralized controller; the main circuit of the inverter includes sequentially connected DC regulated power supplies, H-bridge inverter circuits, LC filter circuits, and feeders, The H-bridge inverter circuit features a S 1 -S 4 Four power switching tubes, the inverter also includes a drive and protection circuit, and a local controller; several parallel inverters are connected to a common bus through the feeder, and linear and nonlinear loads are connected to the common bus , the common bus is also equipped with a centralized controller; the structure diagram of the isolated isl...

Embodiment 2

[0100] According to the method for controlling parallel power sharing of multiple inverters in an island microgrid in Embodiment 1, it is further defined as, in the step (1), the centralized controller controls the common bus voltage u pcc Carry out sampling, processing and calculation to obtain the d coordinate component u of the h order harmonic component of the common bus voltage in the dq coordinate system pcch_d and the q-coordinate component u pcch_q , the specific steps include:

[0101] a. The centralized controller extracts the common bus voltage u through the sliding window discrete Fourier transform SDFT pcc Fundamental component u pccf_α and the h harmonic component u pcch_α , for u pccf_α Delay a quarter of the power frequency cycle to get the corresponding conjugate value u pccf_β , for u pcch_α Delay a quarter of the h-th harmonic frequency period to obtain the corresponding conjugate value u pcch_β ; The transfer function H of the sliding window discrete...

Embodiment 3

[0111] According to the method for controlling parallel power sharing of multiple inverters in an isolated island microgrid in Embodiment 1, it is further defined as follows: in the step (2), the calculation formulas of active power P and reactive power Q are as in formula (IV) Shown:

[0112]

[0113] In formula (IV), s is the complex frequency, ω LPF is the cutoff frequency of the low-pass filter, ω LPF It is 37.7rad / s.

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Abstract

Disclosed is an island micro-grid multi-inverter parallel power split control method. Sliding window discrete Fourier transformation is not included in local controllers of inverters, and transmission quantity of an integrated controller is subjected to dq / alfabeta coordinate transformation by the aid of phase angles of droop control output reference voltage. Fundamental-wave virtual impedance voltage and filter capacitor voltage are subtracted from the droop control output reference voltage to acquire a difference value inputted into first quasi proportional resonant control for voltage regulation; the filter capacitor voltage is added to the hth harmonic-wave virtual impedance voltage to acquire a sum value inputted in second quasi proportional resonant control for voltage regulation; the difference of output quantity of the first quasi proportional resonant control and output quantity of the second quasi proportional resonant control is taken as reference current. The method is applied to an island micro-grid multi-inverter parallel power split control system under complicated conditions of nonlinear load bearing, difference of feeder impedance of the inverters, inconformity of rated capacities and the like, inverter output power split control is realized, and loop currents among the inverters are effectively restrained.

Description

technical field [0001] The invention relates to a method for controlling parallel power equalization of multi-inverters in an isolated island microgrid, and belongs to the technical fields of distributed power generation and smart grids. Background technique [0002] In order to solve the technical problems of connecting distributed power sources to the power grid, scholars related to power systems have proposed the concept of micro-grids. A microgrid is a local power generation system that is composed of distributed micro sources, energy conversion devices, and local loads interconnected through a network, and can realize self-control, protection, and management. In the microgrid, most distributed micro-sources are connected to the AC bus through the inverter interface, thus forming a multi-inverter parallel operation environment. [0003] Due to the variety of local loads on the AC bus, there are inevitably nonlinear loads, which brings great challenges to the inverter co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/493H02J3/38
CPCH02J3/38H02J3/388H02M7/493
Inventor 张庆海吕志鹏刘安华郭维明郭峰李洪博董铁孝石星昊顾卫山
Owner STATE GRID CORP OF CHINA
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