Unlock instant, AI-driven research and patent intelligence for your innovation.

Direct current power distribution network pilot protection method and system based on S transformation frequency domain impedance

A technology of DC distribution network and frequency domain impedance, which is applied in the direction of power transmission AC network, emergency protection circuit device, measuring power, etc., can solve the problem of noise and transition resistance interference, the influence of branch line load, and the complexity of wavelet transform calculation method and other problems, to achieve good economy, low communication bandwidth requirements, and shorten the recognition time

Active Publication Date: 2022-05-17
SHANDONG UNIV
View PDF3 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is suitable for various fault types, but the calculation method based on wavelet transform is complicated
[0011] The existing technology uses the first and second order derivatives of the fault transient current as a criterion to judge the fault section. This method can detect and identify the fault within a few milliseconds, while avoiding the problem of communication delay. However, the method is vulnerable to noise and transition Resistance Interference
The existing technology also judges the fault location by calculating the inductance value from the fault point to the line in the time domain. This method is less affected by high resistance, but this method is only suitable for radial topology and is easily affected by branch line loads.
[0012] In summary, the inventors found that the protection method of the flexible DC distribution network may be affected by factors such as high transition resistance and converters, or have high requirements for communication and data synchronization

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
  • Direct current power distribution network pilot protection method and system based on S transformation frequency domain impedance
  • Direct current power distribution network pilot protection method and system based on S transformation frequency domain impedance
  • Direct current power distribution network pilot protection method and system based on S transformation frequency domain impedance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] refer to Figure 7 , the invention discloses a multi-terminal flexible DC distribution network longitudinal protection method based on S-transform frequency domain impedance, which includes the following steps:

[0056] (1) Real-time collection of DC voltage signals and current signals of nodes where DC line protection is installed;

[0057] (2) Construct the absolute value of the sudden change in voltage as the start-up criterion according to the characteristics of the rapid drop of the DC line after the fault, and judge whether the DC voltage satisfies the start-up condition of the sudden change in voltage. Return to step (1);

[0058] (3) Calculate the S-transformed voltage and S-transformed current of the DC line in a specific frequency band after the fault, and use the ratio of the S-transformed voltage to the S-transformed current as the S-transformed frequency-domain impedance, thereby obtaining the S-transformed frequency-domain reactance and frequency-domain r...

Embodiment 2

[0150] This embodiment provides a flexible DC distribution network longitudinal protection system based on S-transform frequency domain impedance, which specifically includes the following modules:

[0151] A signal acquisition module, which is used to acquire the DC voltage signal and current signal of the node where the DC line protection is installed;

[0152] The fault start judging module constructs the absolute value of the voltage mutation as the start criterion according to the characteristics of the rapid drop of the DC line after the fault, and judges whether the DC voltage meets the low voltage start condition, and if so, judges that the DC line is faulty.

[0153] S-transform frequency-domain impedance value calculation module, which is used to perform S-transform on DC voltage and DC current, and use the ratio of S-transform voltage and S-transform current as S-transform frequency-domain impedance to obtain S-transform frequency-domain resistance and frequency-doma...

Embodiment 3

[0158] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the flexible DC distribution network longitudinal connection based on S-transform frequency domain impedance as described in Embodiment 1 is provided. Steps in the protection method.

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 provides a direct-current power distribution network pilot protection method and system based on S transformation frequency domain impedance. The method comprises the following steps: acquiring a direct-current voltage signal and a current signal of a node at a direct-current line protection installation position; judging whether the direct-current voltage meets a low-voltage starting condition or not, if so, determining that the direct-current line has a fault, and otherwise, obtaining the direct-current voltage signal and the current signal again; calculating the S transformation frequency domain reactance value and the frequency domain resistance value of the direct current line in the set frequency band after the fault; and S transformation frequency domain reactance polarity direction determination and resistance value, reactance value and corresponding threshold value determination are respectively carried out to determine the fault type. According to the method, the near-end fault can be quickly identified by using the direction criterion and the resistance criterion of the single end, and the identification time of the near-end fault is shortened. For a far-end fault or a high transition resistance fault, a pilot protection criterion is adopted to cope with the influence of the converter and the transition resistance on the protection reliability.

Description

technical field [0001] The invention belongs to the technical field of relay protection for flexible DC distribution networks, and in particular relates to a DC distribution network longitudinal protection method and system based on S-transform frequency-domain impedance. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] The flexible DC distribution network based on modular multilevel converter (MMC) has the advantages of flexible operation, large power supply capacity and high operational reliability. With the rapid development of wind power and photovoltaic-based renewable energy technologies, it has broad application prospects in power distribution systems. Compared with the AC distribution network, when a short-circuit fault occurs in the flexible DC distribution network, the fault current rises rapidly and has a high peak value, and th...

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
Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/52G01R31/58H02J3/36
CPCH02H7/263H02H7/268G01R31/52G01R31/58H02J3/36
Inventor 邹贵彬魏秀燕张烁张成泉
Owner SHANDONG UNIV