Method for averagely controlling parallel power of inverters of low-voltage micro-grid

A multi-inverter and micro-grid technology, applied in the direction of sustainable manufacturing/processing, single-network parallel feeding arrangement, climate sustainability, etc., can solve harmonic power and feeder impedance inconsistency inverter power sharing control , Affect the fast response speed of the system, and the program has a large amount of calculation, etc.

Inactive Publication Date: 2015-06-24
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, frequency division to detect the characteristic sub-harmonic power, and then calculate and synthesize the harmonic reference voltage for the characteristic sub-harmonic respectively, so that the specific implementation The process is too complicated, and the calculation amount of the program is relatively large, which may affect the fast 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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  • Method for averagely controlling parallel power of inverters of low-voltage micro-grid
  • Method for averagely controlling parallel power of inverters of low-voltage micro-grid

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Experimental program
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Embodiment 1

[0080] A low-voltage microgrid multi-inverter parallel power sharing control method, the method is suitable for a low-voltage microgrid multi-inverter parallel power sharing control system, the low-voltage microgrid multi-inverter parallel power sharing The control system includes a number of parallel inverters, a common bus, linear and nonlinear loads, and a centralized controller; the main circuit of the inverter includes a DC stabilized power supply, an H-bridge inverter circuit, and an LC filter circuit that are connected in sequence. , feeder, the H-bridge inverter circuit is provided with S 1 -S 4 Four power switch tubes, the inverter also includes a drive and protection circuit and a local controller; a number of parallel inverters are connected to a common bus through the feeder, and the common bus is connected with linear and nonlinear loads , the common bus is also provided with a centralized controller;

[0081] The centralized controller performs sampling process...

Embodiment 2

[0100]The method for controlling power sharing in parallel with multiple inverters in a low-voltage microgrid according to Embodiment 1 is further limited in that, in the step (1), the centralized controller controls the common bus voltage u pcc Perform sampling, processing and calculation to obtain the d coordinate component u of the h-th harmonic component of the common bus voltage in the dq coordinate system pcch_d and the q coordinate component u of the h harmonic component of the common bus voltage in the dq coordinate system pcch_q , the specific steps include:

[0101] a. The centralized controller adopts the sliding window discrete Fourier transform SDFT to extract the common bus voltage u pcc The fundamental component u of pccf_α and the common bus voltage u pcc The h harmonic component u of pcch_α , to the common bus voltage u pcc The fundamental component u of pccf_α Delay a quarter of the power frequency cycle to get the common bus voltage u pcc The fundamen...

Embodiment 3

[0111] The method for controlling the parallel power sharing of multiple inverters in a low-voltage microgrid according to Embodiment 1 is further limited as follows: in the step (3), the instantaneous active power p obtains the active power of the inverter through digital low-pass filtering. The average value of power P and the virtual instantaneous reactive power q are obtained by digital band-pass filtering to obtain the average value of reactive power Q of the inverter. The calculation formula is shown in formula (IV):

[0112] P = ω o s + ω o p Q = ...

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Abstract

The invention provides a method for averagely controlling parallel power of inverters of a low-voltage micro-grid. A method of multiplying feeder line current and virtual complex impedances to obtain base wave virtual impedance voltage is used, output impedances of the inverters are designed to be ohmic and are matched with features of electrical parameters of a feeder line of the low-voltage micro-grid, and droop control output reference voltage is calculated and synthesized by a method of controlling power droop under the condition of ohmic equivalent output impedances; and a phase angle of the droop control output reference voltage is extracted and replaces a phase angle of common busbar voltage to perform dq/alpha beta coordinate transformation, and delay and distortion which are caused by the reason that the phase angle of the common busbar voltage is transmitted to a local controller from an integrated controller through low-bandwidth communication are avoided. When the method is used for a system for averagely controlling the parallel power of the inverters of the low-voltage micro-grid under the conditions that a nonlinear load exists, the feeder line impedances of the inverters are different, and the rated capacities of the inverters are different and the like, average control on the output power of the inverters can be realized, and circulation of the inverters can be restrained effectively.

Description

technical field [0001] The invention relates to a low-voltage microgrid multi-inverter parallel power sharing control method, which belongs to the technical field of distributed power generation and smart grid. Background technique [0002] In order to solve the technical problem of connecting distributed power to the power grid, scholars related to the power system put forward the concept of microgrid. Microgrid is a local power generation system that is composed of distributed micro-sources, energy conversion devices and local loads interconnected through a network, which can realize self-control, protection and management. In the microgrid, most of the distributed microsources 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 inverter control in microgrids: in addition to c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/46
CPCY02P80/14H02J3/46
Inventor 张庆海吕志鹏刘安华李洪博王军蔡军石星昊郭亚峰徐跃东
Owner STATE GRID CORP OF CHINA
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