Mixed island detection method based on combination of slide mode frequency shift method and passive method

A technology of frequency offset and island detection, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems of large blind area of ​​passive method detection and increase of THD of grid-connected point current, so as to prevent misoperation and reduce THD Effect

Inactive Publication Date: 2016-10-12
NANCHANG UNIV
View PDF14 Cites 3 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the active method causes the current THD of the grid-connected point to increase and the blind area of ​

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Mixed island detection method based on combination of slide mode frequency shift method and passive method
  • Mixed island detection method based on combination of slide mode frequency shift method and passive method
  • Mixed island detection method based on combination of slide mode frequency shift method and passive method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0031] The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and working principles.

[0032] Such as figure 1 As shown, the present invention is an islanding detection algorithm based on the synovium frequency offset method and the passive method. Mainly in the photovoltaic grid-connected model, the inverter output voltage and current, and the load terminal voltage and current are sampled in real time. According to the difference between the inverter output and the active power and reactive power consumed by the load, different islanding detection algorithms are switched to generate a reference current, and after The PI controller makes the actual output current track the reference input current, controls the frequency of the inverter output current to deviate from the threshold, and then disconnects the power grid to achieve the purpose of island detection.

[0033] Such as figure 2 Shown, the ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

Abstract

The invention relates to a mixed island detection method based on a combination of a slide mode frequency shift method and a passive method. The method comprises that an inversion output current, a load current and related values are collected, and inversion output active power and reactive power and load consumption active power and reactive power of are calculated; according to a difference between the inversion output active power and the load consumption active power as well as a difference between the inversion output reactive power and the load consumption reactive power, an over/under frequency detection method in the passive method is used to obtain a reference current value, or the slide mode frequency shift method is used to obtain the reference current value. According to the invention, load change can be tracked, and different algorithms are switched in real time; switching mistakes of the island detection algorithms caused by instant voltage and current jump can be prevented; and blind detection areas can be reduced and the detection speed can be increased compared with those when the passive method is used independently, and THD of the power-grid current can be reduced compared with that only the slide-mode frequency shift method is used.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation. Background technique [0002] Island operation means that when the power grid is interrupted due to electrical failure, misoperation or natural factors, the photovoltaic micro-grid power supply system continues to output power to the grid and supply power to local loads as an independent power source, thus forming a self-sufficient power supply that the grid cannot control isolated island. When the distributed photovoltaic power generation system is operating in an isolated state, it may affect the power quality or even damage the electrical equipment, and may endanger the personal safety of maintenance personnel in severe cases. Therefore, no matter from the aspect of safety or reliability, the islanding operation status should be detected effectively in time, and the photovoltaic inverter should be disconnected from the point of common connection (PCC), which is the islan...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): G01R31/00
CPCG01R31/00
Inventor 余运俊衷国瑛
Owner NANCHANG UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap