CN101452632B - Single-phase earth fault diagnostic equipment - Google Patents

Abstract

The invention relates to a single-phase ground fault diagnosis device, which comprises a host monitoring module and slave signal acquisition and processing modules, wherein the host monitoring module is provided with a liquid crystal display, a keyboard, a human-machine interface and a communication interface of a comprehensive automatic system of a substation; the slave signal acquisition and processing modules monitor operational parameters of an electric network in real time, and find out and identify faults; the host module and the slave modules are communicated with each other through Ethernet; and the host module can drive a plurality of slave modules. Compared with the prior art, the single-phase ground fault diagnosis device can accurately identify the fault type and select grounding branch circuits.

Description

Single-phase ground fault diagnosis device

technical field

The invention relates to a single-phase grounding fault diagnosis device for a small current grounding power grid, in particular to a single-phase grounding fault diagnosis device that fully utilizes the complete transient and steady state information of a small current grounding power grid, and the device is used for medium-voltage power distribution in the net.

Background technique

In the medium-voltage distribution network, single-phase ground faults account for more than 80% of the total faults. When a single-phase ground fault occurs, accurate selection of grounding lines is of great significance to the operation and management of the power grid.

The existing small-current grounding grid line selection device often uses the rise of the neutral point voltage of the grid as the criterion for the occurrence of a ground fault, but in fact there are many reasons for the rise of the neutral point voltage, not necessarily the occurrence Single-phase grounding; in addition, the sampling rate of the current line selection device is low, no more than 5KB/S, and it cannot continuously collect signals, so it is impossible to comprehensively monitor changes in grid parameters, and cannot make full use of the stability and stability of the grid before and after a fault occurs. Transient information to identify faults.

Contents of the invention

The object of the present invention is to provide a single-phase grounding fault diagnosis device for small current grounding power grid in order to overcome the defects of the above-mentioned prior art, which can accurately identify the fault type and select the grounding branch.

The purpose of the present invention can be achieved through the following technical solutions: a single-phase ground fault diagnosis device is characterized in that, comprising:

The upper monitoring module has a liquid crystal display and a keyboard, provides a man-machine interface, and provides a communication interface with the integrated automation system of the substation;

The lower signal acquisition and processing module, which monitors the operating parameters of the power grid in real time, finds faults, and identifies faults;

Communication between upper and lower modules via Ethernet;

One upper module can have multiple lower modules.

The lower signal acquisition and processing module includes a signal acquisition module and a signal processing module, the two modules are connected through a data bus and an address bus, and one signal processing module can have multiple signal acquisition modules.

The signal acquisition module, each of which supports the acquisition of multiple signals; the AD conversion function is integrated on the module; the sampling rate of each signal is 10KB/S, and the frequency response of the signal conditioning channel is 3KHZ; each signal is sampled synchronously ;The collected signals include: A phase-to-ground voltage, B phase-to-ground voltage, C phase-to-ground voltage, AC line voltage, BC line voltage, AB line voltage, neutral point voltage, neutral point current when the power grid is grounded through the arc suppression coil And the zero-sequence current of each branch.

In the lower signal acquisition and processing module, the acquisition time of each signal of the signal acquisition module is controlled by the signal processing module through the data and address bus, and read by the signal processing module.

The signal processing module can control multiple signal acquisition modules to collect signals from various channels in a real-time, continuous and synchronous manner; can simultaneously store sampling data of more than 10 power frequency cycles in each channel; has an Ethernet interface; adopts a holographic method for fault diagnosis and line selection.

Compared with the prior art, the present invention adopts a multi-CPU structure, distributes signal collection and processing, and divides signal collection, signal processing, wave recording data storage and management into different CPUs for processing, which greatly improves system performance and ensures Real-time, continuous, synchronous, high sampling rate, multi-channel signal acquisition enables the device to diagnose faults using process-based holographic fault diagnosis methods, thus ensuring the accuracy of fault identification and line selection.

Description of drawings

Fig. 1 is a system structure diagram of the present invention;

Fig. 2 is a schematic structural diagram of a lower signal acquisition and processing module;

FIG. 3 is a schematic structural diagram of the signal acquisition module.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

The device of the invention is composed of an upper monitoring module and a lower signal acquisition and processing module.

The upper monitoring module has a liquid crystal display and a keyboard, provides a man-machine interface, and provides a communication interface with the integrated automation system of the substation. The lower signal acquisition and processing module monitors the operating parameters of the power grid in real time, finds faults, and identifies faults. The upper and lower modules communicate through Ethernet, and one upper module can have multiple lower modules. The system structure of the present invention is shown in Figure 1.

The lower signal acquisition and processing module includes a signal acquisition module and a signal processing module. The two modules are connected through a data bus and an address bus. A signal processing module can have multiple signal acquisition modules. The structure of the lower signal acquisition and processing module is shown in Figure 2.

Each signal acquisition module supports the acquisition of multiple signals; the AD conversion function is integrated on the module; the sampling rate of each signal is 10KB/S, and the frequency response is 3KHZ; the signals of each channel are sampled synchronously; the collected signals include: A relative ground Voltage, B phase-to-ground voltage, C phase-to-ground voltage, AC line voltage, BC line voltage, AB line voltage, neutral point voltage, neutral point current (when the power grid is grounded through the arc suppression coil) and zero-sequence current of each branch .

According to different acquisition signals, the signal acquisition module is divided into two types, one is the bus signal acquisition module, and the other is the branch signal acquisition module. Among them, the bus section signal acquisition module collects A phase-to-ground voltage, B phase-to-ground voltage, C phase-to-ground voltage, AC line voltage, BC line voltage, AB line voltage, neutral point voltage, and neutral point current (when the power grid passes arc suppression When the coil is grounded); the branch signal acquisition module collects the branch zero-sequence current signal. The structure of the signal acquisition module is shown in Figure 3.

The acquisition time of each signal of the signal acquisition module is controlled by the signal processing module through the data and address bus, and read by the signal processing module. The signal processing module can control multiple signal acquisition modules to collect signals from various channels in real time, continuously and synchronously; it can simultaneously store sampling data of more than 10 power frequency cycles of each channel; the signal processing module has an Ethernet interface to communicate with the upper monitoring module ; The signal processing module adopts the holographic method for fault diagnosis and line selection.

Example

The upper monitoring module uses PC104 as the core processor, with a color LCD screen and keyboard, and the whole module is packed into a 19-inch, 4U high chassis.

The lower signal acquisition and processing module adopts a standard European-style subrack and a 4U high chassis. The bus signal acquisition module, the zero-sequence current acquisition module, and the signal processing module are separate circuit boards, and the boards are connected through the backplane, and the backplane uses the data and address bus.

The bus signal acquisition module supports A phase-to-ground voltage, B phase-to-ground voltage, C phase-to-ground voltage, AC line voltage, BC line voltage, AB line voltage, neutral point voltage, and neutral point current (when the power grid is grounded through the arc suppression coil ) collection. The zero-sequence current acquisition module supports the acquisition of 8-way zero-sequence current signals.

The signal processing module uses DSP with a main frequency of 600M as the core processor and supports Ethernet. The upper and lower modules are connected through Ethernet.

For the signal conditioning part, a precision current transformer is used for the current signal, and a precision voltage transformer is used for the voltage part to access the signal. The frequency response of the transformer is 3KHZ, the measurement range should meet the requirements of the field signal, and the maximum withstand signal should be 3 times of the maximum measurable signal. The signal conditioning circuit behind the transformer also needs to meet the requirement of a frequency response of 3KHZ.

The AD conversion module adopts 16-bit precision AD, the frequency is 1MHZ, and the frequency of the analog switch is also 1MHZ.

The signal processing module controls the sampling time and the channel of the signal acquisition module. Specifically, the signal processing module starts a time manager, controls the multi-channel analog switch on the corresponding signal acquisition module to access the signal to be collected when the sampling time arrives, starts the AD conversion process at the same time, and reads the conversion result.

In the memory space of the signal processing module, a space that can store 20 power frequency cycle sampling data is reserved for each signal, forming a circular sampling buffer pool in which the latest sampling data is stored.

Using the sampling data in the buffer pool, the holographic method is used to monitor the occurrence of faults, identify faults and select lines. The specific methods will not be repeated here.

When a monitoring fault occurs, the signal processing module transmits the recorded wave data to the upper monitoring module through Ethernet, and records it in the non-volatile memory of the upper computer. In the host monitoring module, users can view fault records, fault waveforms and fault identification results.

For a grid with three bus sections, the first bus section has 7 branches, the second bus section has 16 branches, and the third bus section has 19 branches, a host monitoring module and 3 A lower signal acquisition and processing module is used to realize the fault identification and line selection of the power grid. Among them, the signal acquisition and processing module corresponding to the first bus section needs a signal processing module, a bus signal acquisition module, and a zero-sequence current acquisition module; the signal acquisition and processing module corresponding to the second bus section needs a signal processing module , a bus signal acquisition module, and two zero-sequence current acquisition modules; the signal acquisition and processing module corresponding to the third bus section requires a signal processing module, a bus signal acquisition module, and three zero-sequence current acquisition modules.

Claims (3)

1. A single-phase ground fault diagnostic device, comprising: The upper monitoring module has a liquid crystal display and a keyboard, provides a man-machine interface, and provides a communication interface with the integrated automation system of the substation; The lower signal acquisition and processing module, which monitors the operating parameters of the power grid in real time, finds faults, and identifies faults; Communication between upper and lower modules via Ethernet; One upper module can carry multiple lower modules; The lower signal acquisition and processing module includes a signal acquisition module and a signal processing module, the two modules are connected by a data bus and an address bus, and one signal processing module can have multiple signal acquisition modules; It is characterized in that each of the signal acquisition modules supports the acquisition of multiple signals; the AD conversion function is integrated on the module; the sampling rate of each signal is 10KB/S, and the frequency response of the signal conditioning channel is 3KHZ; Synchronous sampling of line signals; the collected signals include: A phase-to-ground voltage, B phase-to-ground voltage, C phase-to-ground voltage, AC line voltage, BC line voltage, AB line voltage, neutral point voltage, when the power grid is grounded through the arc suppression coil Neutral point current and zero-sequence current of each branch. 2. single-phase grounding fault diagnosis device according to claim 1, is characterized in that, described lower signal acquisition and processing module, the acquisition moment of each road signal of its signal acquisition module is controlled by signal processing module by data and address bus , and read by the signal processing module. 3. The single-phase ground fault diagnosis device according to claim 1, wherein the signal processing module can control a plurality of signal acquisition modules to collect each signal in real time, continuously and synchronously; each channel 10 can be stored simultaneously Sampling data above a power frequency cycle; with Ethernet interface; using holographic method for fault diagnosis and line selection.

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