CN-122026273-A - Micro-grid state detection system and detection method

CN122026273ACN 122026273 ACN122026273 ACN 122026273ACN-122026273-A

Abstract

The embodiment of the application provides a micro-grid state detection system and a micro-grid state detection method, and particularly relates to the technical field of electric power. The system comprises a large power grid bus, a micro power grid bus, a harmonic signal main device, harmonic signal auxiliary devices, a micro power grid power supply and circuit breakers, wherein the harmonic signal main device is connected with the large power grid bus, the micro power grid bus is connected with the large power grid bus through a plurality of circuit breakers, the micro power grid power supply and the harmonic signal auxiliary devices are connected with the micro power grid bus, the harmonic signal main device is used for injecting harmonic signals into the large power grid bus and acquiring harmonic signal characteristics fed back by the harmonic signal auxiliary devices, the micro power grid is determined to be in a grid-connected state or an off-grid state based on the harmonic signal characteristics, and the harmonic signal auxiliary devices are used for detecting the harmonic signals on the micro power grid bus and extracting the harmonic signal characteristics of the harmonic signals when the harmonic signals are detected and feeding back to the harmonic signal main device, so that the effects of improving the micro power grid and off-grid state detection efficiency and controlling the detection cost are achieved.

Inventors

LI XIANJUN
GUO LIDONG
YU HAI
JIANG ZONGNAN
CHEN YUSHENG
YANG LONGFEI
TANG YIN

Assignees

中石油深圳新能源研究院有限公司
中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241108

Claims (10)

1. The micro-grid state detection system is characterized by comprising a large-power-grid bus, a micro-power-grid bus, harmonic signal main equipment, harmonic signal auxiliary equipment, a micro-power-grid power supply and a circuit breaker; The harmonic signal main equipment is connected with the large power grid bus, the micro power grid bus is connected with the large power grid bus through a plurality of circuit breakers, and the micro power grid power supply and the harmonic signal slave equipment are connected with the micro power grid bus; The harmonic signal main equipment is used for injecting a harmonic signal into the large power grid bus, acquiring a harmonic signal characteristic fed back by the harmonic signal auxiliary equipment, and determining that the micro power grid is in a grid-connected state or an off-grid state based on the harmonic signal characteristic; The harmonic signal slave device is used for detecting the harmonic signal on the micro-grid bus and extracting the harmonic signal characteristic of the harmonic signal and feeding back the harmonic signal characteristic to the harmonic signal master device when the harmonic signal is detected.
2. The micro-grid state detection system according to claim 1, wherein, The harmonic signal main equipment is further used for determining the distance between the micro-grid bus and the large-grid bus based on the time for acquiring the harmonic signal characteristics.
3. The micro-grid state detection system according to claim 2, wherein, The harmonic signal slave device is further configured to, when the harmonic signal is detected, establish an association relationship between a slave device identifier of the harmonic signal slave device and the harmonic signal feature, and feed back the association relationship between the slave device identifier and the harmonic signal feature to the harmonic signal master device; the harmonic signal master device is further configured to determine an on-off condition of a grid line between the micro grid and the large grid based on the obtained association relationship between the slave device identifier and the harmonic signal feature and the pre-stored association relationship between the slave device identifier and the micro grid.
4. The micro-grid state detection system according to claim 3, wherein, The harmonic signal master device is further configured to determine the number of micro-grids running in grid connection with the large grid at the current moment based on the obtained association relationship between the slave device identifier and the harmonic signal feature and the obtained association relationship between the slave device identifier and the micro-grids.
5. The micro grid state detection system according to any one of claims 1 to 4, further comprising a first voltage transformer; one end of the first voltage transformer is connected with the large power grid bus, and the open triangular secondary end of the first voltage transformer is connected with the harmonic signal main equipment; the harmonic signal main equipment is used for injecting the harmonic signal into all feeder lines of the large power grid bus through the first voltage transformer.
6. The micro grid state detection system according to any one of claims 1 to 4, further comprising a grounding transformer and a first grounding resistor; one end of the grounding transformer is connected with the large power grid bus, a neutral point of the grounding transformer is connected with the first grounding resistor, and the harmonic signal main equipment is connected to two ends of the first grounding resistor in a parallel connection mode; the harmonic signal main equipment is used for injecting the harmonic signal into all feeder lines of the large power grid bus through the grounding transformer and the first grounding resistor.
7. The micro grid state detection system according to any one of claims 1 to 4, further comprising a main transformer and a second ground resistor; One end of the main transformer is connected with the large power grid bus, the neutral point of the end is connected with the second grounding resistor, and the harmonic signal main equipment is connected to two ends of the second grounding resistor in a parallel connection mode; The harmonic signal main equipment is used for injecting the harmonic signal into all feeder lines of the large power grid bus through the main transformer and the second grounding resistor.
8. The micro grid state detection system according to any one of claims 1 to 4, further comprising a second voltage transformer; One end of the second voltage transformer is connected with the micro-grid bus, and the open triangular secondary end of the second voltage transformer is connected with the harmonic signal slave equipment; The harmonic signal slave device is used for detecting the harmonic signal on the micro-grid bus through the second voltage transformer.
9. The micro-grid state detection system according to any one of claims 1 to 4, wherein, The harmonic signal characteristics comprise harmonic amplitude values, and the harmonic signal main equipment is further used for generating a reminding signal when the harmonic amplitude values meet preset amplitude value conditions, wherein the reminding signal is used for reminding that the micro-grid is in an off-grid state.
10. A micro-grid state detection method, characterized by being applied to the micro-grid state detection system as claimed in any one of claims 1 to 3, comprising: The harmonic signal main equipment generates a target harmonic signal based on the acquired detection instruction, wherein the target harmonic signal is a harmonic signal which is generated by the detection instruction indication; And the harmonic signal main equipment injects the target harmonic signal into the large power grid bus to determine whether the micro power grid is in a grid-connected state or an off-grid state.

Description

Micro-grid state detection system and detection method Technical Field The application relates to the technical field of power, in particular to a micro-grid state detection system and a detection method. Background With the development of technologies such as the internet of things, big data and artificial intelligence, the micro-grid will develop towards more intelligent and automatic directions. The micro-grid is a small power generation and distribution system composed of a distributed power supply, an energy storage device, an energy conversion device, a load, a monitoring and protecting device and the like. The micro-grid is an autonomous system capable of realizing self-control, protection and management, and can be operated in a grid-connected mode with a large power grid or independently operated in an isolated power grid mode. The micro-grid parallel-off-grid state detection is an important link for ensuring the stable operation and efficient management of the micro-grid. The micro-grid parallel-to-grid state detection method mainly comprises the methods of detection based on grid-connected open-and-close states, detection based on grid-connected tie line power, detection based on grid-connected point voltage and frequency, detection based on a wide-area measurement system and the like. At present, the method is applied to different degrees, and the micro-grid off-grid state detection method has advantages and disadvantages. Disclosure of Invention The embodiment of the application provides a micro-grid state detection system and a detection method, which are used for improving the micro-grid off-grid state detection efficiency and controlling the detection cost. In a first aspect, an embodiment of the present application provides a micro-grid state detection system, including a large-grid bus, a micro-grid bus, a harmonic signal master device, a harmonic signal slave device, a micro-grid power supply and a circuit breaker; The harmonic signal main equipment is connected with the large power grid bus, the micro power grid bus is connected with the large power grid bus through a plurality of circuit breakers, and the micro power grid power supply and the harmonic signal slave equipment are connected with the micro power grid bus; The harmonic signal main equipment is used for injecting a harmonic signal into the large power grid bus, acquiring a harmonic signal characteristic fed back by the harmonic signal auxiliary equipment, and determining that the micro power grid is in a grid-connected state or an off-grid state based on the harmonic signal characteristic; The harmonic signal slave device is used for detecting the harmonic signal on the micro-grid bus and extracting the harmonic signal characteristic of the harmonic signal and feeding back the harmonic signal characteristic to the harmonic signal master device when the harmonic signal is detected. In one possible implementation of the method according to the invention, The harmonic signal main equipment is further used for determining the distance between the micro-grid bus and the large-grid bus based on the time for acquiring the harmonic signal characteristics. In one possible implementation of the method according to the invention, The harmonic signal slave device is further configured to, when the harmonic signal is detected, establish an association relationship between a slave device identifier of the harmonic signal slave device and the harmonic signal feature, and feed back the association relationship between the slave device identifier and the harmonic signal feature to the harmonic signal master device; the harmonic signal master device is further configured to determine an on-off condition of a grid line between the micro grid and the large grid based on the obtained association relationship between the slave device identifier and the harmonic signal feature and the pre-stored association relationship between the slave device identifier and the micro grid. In one possible implementation of the method according to the invention, The harmonic signal master device is further configured to determine the number of micro-grids running in grid connection with the large grid at the current moment based on the obtained association relationship between the slave device identifier and the harmonic signal feature and the obtained association relationship between the slave device identifier and the micro-grids. In one possible embodiment, the system further comprises a first voltage transformer; one end of the first voltage transformer is connected with the large power grid bus, and the open triangular secondary end of the first voltage transformer is connected with the harmonic signal main equipment; the harmonic signal main equipment is used for injecting the harmonic signal into all feeder lines of the large power grid bus through the first voltage transformer. In one possible embodiment, the device further comprises a grounding transforme