CN107462805A - A kind of short circuit fault of power distribution network protection and localization method - Google Patents

Abstract

The invention discloses a kind of protection of short circuit fault of power distribution network and localization method.It solves the problems, such as that the lookup of current short fault location needs to expend substantial amounts of human and material resources and extends failure existence time in power distribution network; after single-phase grounding fault generation; the zero-sequence current Sudden Changing Rate each measured is uploaded to main website by each Protection Module; main website judges singlephase earth fault circuit and fault section according to the situation of each measurement point zero-sequence current Sudden Changing Rate; so as to realize being automatically positioned for all kinds of short trouble sections on distribution line, guidance is provided for staff scene investigation failure.

Description

A short-circuit fault protection and location method for distribution network

technical field

The invention relates to a short-circuit fault detection technology in a power system, in particular to a short-circuit fault protection and positioning method for a power distribution network.

Background technique

The neutral point indirect grounding system is generally adopted in my country's medium and low voltage distribution networks. Due to the large number of power supply network branches in the distribution network, the network structure is complex and changeable, and the line laying environment is complex, which increases the probability of failure and causes the occurrence of faults in the distribution network. The probability of failure is relatively high compared to the transmission grid. The gradual application of distribution network automation provides the possibility for the location of various short-circuit fault sections. A variety of fault section location algorithms based on distribution network automation have been proposed and applied to practical projects, but they have not been implemented in distribution network. Short-circuit fault location in automated power supply systems is still a difficult problem. The search for the fault location requires a lot of manpower and material resources, and prolongs the time that the fault exists in the distribution network. Therefore, it is of great significance to quickly and accurately find the fault section to provide power supply reliability of the distribution network.

Contents of the invention

In the present invention, a microcomputer protection module with a wireless communication function is installed at the feeder outlet of the substation busbar, the section switch of the power supply line, and the branch line switch. The microcomputer protection module collects the phase voltage, zero-sequence voltage and phase current of this section in real time , zero-sequence current, use the sudden change of each voltage and each phase current to judge whether there is a fault and the type of fault, for the phase-to-phase short circuit, it acts on the circuit breaker trip according to the protection configuration, and uploads the result to the master station, and the master station uploads it according to each protection module According to the results of the single-phase grounding short circuit, each microcomputer protection module uploads the measured zero-sequence current mutation to the main station, and the master station judges the single-phase grounding fault according to the zero-sequence current mutation of each measurement point lines and faulty sections. In this way, the automatic positioning of various short-circuit fault sections on the distribution line can be realized, and guidance can be provided for the staff to troubleshoot on-site.

A microcomputer protection module with wireless communication function is installed at the feeder outlet of the substation bus, the section switch along the power supply line and the branch line switch. The wireless communication adopts the GPRS public network, and the microcomputer protection module has the functions of three-stage current protection reflecting the phase-to-phase short-circuit fault of the distribution line, zero-sequence current collection and mutation calculation, three-phase voltage and zero-sequence voltage collection and calculation functions. The power supply line protection and positioning master station is installed in the substation to which the power supply line belongs. The master station monitors the bus voltage in real time, and communicates with the microcomputer protection module at the feeder exit and each microcomputer protection module along the power supply line through GPRS wireless mode to realize bus voltage measurement, Acquisition of electrical information of a measurement point on the power supply line, judgment of the fault section, and graphical display of line switch status and location of the fault section.

Description of drawings

Figure 1 is a schematic diagram of short-circuit fault protection and section automatic positioning of distribution lines.

detailed description

Figure 1 is a schematic diagram of short-circuit fault protection and section automatic positioning of distribution lines. The distribution line short-circuit fault protection and section automatic positioning system consists of a master station, a microcomputer protection module and a communication system. Among them, microcomputer protection modules are installed at the feeder outlets of the substation bus, and microcomputer protection modules are installed at the section switches and branches along the feeder lines that need fault location; the main station is installed in the substation.

The numbers of the switch on the feed-out line and the microcomputer protection module installed there are the same, and the numbering principle is as follows:

(1) Main line first, then branches;

(2) The switch serial number at the feeder exit is 0, and the switch serial number increases from small to large along the direction from the bus to the load.

This numbering scheme describes the topology of the line.

In the m# feeder line in the example shown in Figure 1, the switch numbers are m ₀ , m ₁ , m ₂ , m ₃ , m ₄ , m ₅ , m ₀ is the switch number at the exit, and m ₁ , m ₂ , m ₃ are The serial number of the switch on the main line, m ₄ and m ₅ are the serial numbers of the switches on the branch line respectively.

Assuming that a single-phase ground short circuit occurs on the m# line in Figure 1, the microcomputer protection module at the main station, the feeder outlet, and the microcomputer protection module on the power supply line can detect this because they all have the functions of collecting and calculating three-phase voltage and zero-sequence voltage. A single-phase-to-ground short-circuit fault occurred in the power supply system. First, the master station will receive the zero-sequence current of each line uploaded by the microcomputer protection module at the feeder exit. The master station will use the well-applied criterion based on the steady-state electrical quantity characteristics of small current grounding faults, and according to the zero-sequence current of each feeder outlet, The zero-sequence voltage of the system can select the faulty line with single-phase grounding. At this time, the line selection result is that a single-phase grounding fault occurs on the m# line. Then, the master station collects the zero-sequence current mutation before and after the fault uploaded by each microcomputer protection module on the m# line, that is, the zero-sequence current at m ₀ , m ₁ , m ₂ , m ₃ , m ₄ , and m ₅ in the example in Figure 1 The sudden change before and after the fault, the master station compares the sudden change before and after the fault of the zero-sequence current at m ₀ , m ₁ , m ₂ , m ₃ , m ₄ , m ₅ with the setting threshold of the zero-sequence current, and it is greater than The one with the threshold value is the fault path, which is searched in ascending order of the serial number, and the section where the last microcomputer protection module is greater than the threshold is located is the section where the fault is located. For example, in Figure 1, a single-phase ground short circuit occurs at point f ₁ of line m#. According to the aforementioned switch numbering principle, the zero-sequence current mutations of m ₀ and m ₁ are greater than the setting threshold, and the section where m ₁ switch is located is a fault section. If a single-phase ground short circuit occurs at point f ₂ of line m# in Figure 1, the zero-sequence current mutations of m ₀ , m ₁ , and m ₅ are greater than the setting threshold, and the section where the switch of m ₅ is located is a fault section.

Assuming that there is a phase-to-phase short circuit on the m# line in Figure 1, the microcomputer protection module at the main station, the feeder outlet, and the microcomputer protection module on the power supply line can detect the power supply system because they all have the functions of collecting and calculating three-phase voltage and zero-sequence voltage A phase-to-phase short circuit fault has occurred. The master station will receive the protection action status information uploaded by the microcomputer protection module on the faulty line (protection tripping or protection inaction), and the master station will judge the faulty section according to the protection action information on the faulty line. According to the selectivity of the protection, the microcomputer protection module in the section where the fault is located uploads the trip information, and the microcomputer protection modules in other places upload the protection non-action information. According to the numbering principle of the switch on the aforementioned line, search in ascending order of the switch serial number, and the section where the microcomputer protection module corresponding to the "protection trip" information is located is the section where the fault is located. For example, in Figure ₁ , a phase-to-phase short circuit occurs at point f1 _of line m#. According to the aforementioned principle _of switch numbering, the protection trip information uploaded by the microcomputer protection module at m1 is the protection trip information, and the section where the m1 switch is located is the faulty section. If a phase-to _- phase short circuit occurs at point f2 of line m# in Figure ₁ , the microcomputer protection module at m5 uploads the protection trip information, and the section where the switch at _m5 is located is the faulty section.

Claims (2)

1. A distribution network short-circuit fault protection and location method, which is to set a microcomputer protection module with wireless communication function at the feeder outlet of the substation busbar, the section switch of the power supply line and the branch line switch, and the microcomputer protection module collects in real time Each phase voltage, zero-sequence voltage and each phase current, zero-sequence current in this section, use each voltage and each phase current sudden change to judge whether there is a fault and the type of fault. Upload the results to the master station, and the master station judges the fault section according to the results uploaded by each protection module; for a single-phase ground short circuit, each microcomputer protection module uploads the measured zero-sequence current mutation to the master station, and the master station according to each Judging the single-phase ground fault line and fault section based on the sudden change of zero-sequence current at the measurement point; thus realizing the automatic positioning of various short-circuit fault sections on the distribution line and providing guidance for the staff to troubleshoot on-site. 2. A distribution network short-circuit fault protection and location method according to claim 1, characterized in that: a wireless communication function is installed at the feeder outlet of the substation busbar, the section switch along the power supply line, and the branch line switch. The microcomputer protection module; the wireless communication adopts GPRS public network, and the microcomputer protection module has the functions of three-stage current protection, zero-sequence current collection and mutation calculation, three-phase voltage and zero-sequence voltage collection and calculation functions to reflect the short-circuit fault between phases of the distribution line ;The substation to which the power supply line belongs installs a power supply line protection and positioning master station. The master station monitors the bus voltage in real time, and communicates with the microcomputer protection module at the feeder exit and each microcomputer protection module along the power supply line through GPRS wireless mode to realize the bus voltage measurement. , Acquisition of electrical information of a measurement point on the power supply line, judgment of the fault section, and graphical display of line switch status and location of the fault section and other information.