Protection Control Panel

Abstract

To provide a protective control panel which is a part of a distribution board and which can easily check for incorrect polarity connections of instrument transformers connected thereto. [Solution] In a protection control panel that constitutes a distribution board that monitors, controls, and protects substation equipment, bus bars, and distribution lines, a protection control panel is installed to detect the current values ​​on the primary and secondary sides of the transformer that constitutes the substation.If the polarity of the instrument transformer connected to the protection control panel is incorrectly connected, the incorrect connection is detected from the phase difference and current value between the primary and secondary sides, and a warning is displayed on the protection control panel.

Description

[Technical field]

[0001] This invention relates to a protection control panel that constitutes a distribution board, and to a technology that can easily check for incorrect polarity connections of instrument transformers connected to it. [Background technology]

[0002] Conventionally, distribution substations are equipped with switchboards that monitor, control, and protect substation equipment, busbars, and distribution lines. The switchboards consist of a distribution control panel and a protection control panel, and the distribution control panel is equipped with units that have monitoring and control functions.

[0003] The protection and control panel is equipped with protection units with protection functions for each protection range, and protection and control units that have control functions in addition to the above protection functions, in accordance with the actual equipment conditions of the substation equipment, bus bars, and distribution lines.

[0004] Moreover, remote monitoring and control are performed from a power supply control center via an IP-TC unit (see Non-Patent Document 1 below). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Aichi Electric Technical Review No. 40 (2019) Page 32

[0006] An example of substation equipment is a transformer, and possible accidents that may occur in a transformer include insulation breakdown caused by mechanical shock or vibration inside the transformer due to a short circuit current resulting from an external accident such as a lightning strike on a power line, insulation breakdown caused by deterioration of the transformer's insulation, and accidents caused by overload.

[0007] If such an accident were to occur, the fault current could generate gas, causing the internal pressure of the tank to rise and damage the tank, or the insulating oil could escape and lead to a fire, so transformers need to be highly protected.

[0008] The most common method of protecting transformers is to detect abnormalities in the transformer early and use a circuit breaker to disconnect it from the transmission line, and abnormalities in the transformer can be detected by a protective relay. Known protective relays include electrical relays that detect abnormalities from fault currents and mechanical relays that detect abnormalities from decomposition gases in the transformer tank.

[0009] As electrical relays, overcurrent relays and differential current relays are known, but for large-capacity transformers such as those installed in substations, differential current relays, which have superior fault detection capabilities, are used.The relay is functionally implemented as a digital relay within the protection unit of the protection control panel mentioned above. Summary of the Invention [Problem to be solved by the invention]

[0010] A differential current relay detects the difference between the current on the primary and secondary sides of a transformer to detect abnormalities. The currents on the primary and secondary sides of a transformer are each detected by an instrument transformer installed in the substation (see Figure 3).

[0011] Here, the instrument transformer has polarity, and the primary terminal K and secondary terminal k are connected to the power supply side, while the primary terminal L and secondary terminal l are connected to the load side, as shown in Figure 4. The cable of the transformer passes through the primary terminals (K terminal, L terminal) of the instrument transformer, and the secondary terminals (k terminal, l terminal) are connected to a protection control panel.

[0012] If the polarity of the instrument transformer is incorrectly connected, the differential current relay will detect an abnormality in the transformer below the original operating value and protect the transformer by pulling apart the electrodes of the circuit breaker to cut off the flow of electricity.

[0013] In other words, the differential current relay, which was originally installed to detect insulation breakdown accidents caused by external accidents or internal faults in the transformer, and accidents caused by overload, was detecting a transformer abnormality due to incorrect connection of the polarity of the instrument transformer.

[0014] Therefore, to prevent the circuit breaker from opening due to incorrect connection of the polarity of the instrument transformer, a test current was passed through the protection control panel, and the calculation results of the differential current relay and measurement function were displayed on the screen (monitor) of a monitoring computer (HI-PC shown in Figure 2) to confirm incorrect connection of the polarity of the instrument transformer.

[0015] In other words, in the past, in order to check for incorrect connection of the polarity of the instrument transformer, it was necessary to connect a checking computer to the protection control panel, which made it difficult to carry out the checking work quickly and also placed a heavy burden on the workers.

[0016] The present invention is intended to solve the above problems, and relates to a protection control panel that makes it possible to quickly and easily check for incorrect polarity connections in instrument transformers, thereby reducing the burden on workers. [Means for solving the problem]

[0017] The invention described in claim 1 is characterized in that it is installed in a protection control panel constituting a distribution board that monitors, controls and protects the equipment, busbars and distribution lines of a substation to detect the current values ​​on the primary and secondary sides of a transformer constituting a substation, and in that, when the polarity of an instrument transformer connected to a protection unit installed in the protection control panel is incorrectly connected, the incorrect connection is detected from the phase difference and current value between the primary and secondary sides, and a warning is displayed on the protection control panel. Effect of the Invention

[0018] According to the invention described in claim 1, incorrect connection of the polarity of the instrument transformer can be quickly and easily confirmed without connecting a monitoring computer to the protection control panel, thereby reducing the burden on workers. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a substation. [Diagram 2] FIG. 1 is a schematic diagram of a switchboard. [Diagram 3]FIG. 2 is a schematic diagram of current intake on the primary and secondary sides. [Figure 4] FIG. 2 is a schematic diagram of an instrument transformer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a schematic diagram of a substation. A substation is roughly composed of various devices such as a transformer that reduces the high voltage electricity sent from a power plant or a higher-level system to a voltage suitable for the lower-level system where it is used, a circuit breaker that opens the electric circuit and cuts off the current when an accident or failure occurs, thereby preventing the accident from spreading, a disconnecting switch that physically disconnects the electric circuit during maintenance, an instrument transformer (instrument transformer, instrument current transformer) for measuring voltage and current, and a lightning arrester that protects equipment from overvoltage caused by lightning. In addition, control equipment that monitors and controls the operation status of each of the above-mentioned devices installed in the substation is installed in an electrical room (not shown).

[0021] The configuration of control equipment varies depending on the type of substation, but in the case of a distribution substation, it is equipped with functions such as collecting common substation information, monitoring and controlling extra-high voltage equipment, automatic power receiving switching, and reverse power flow detection, and examples include a distribution control panel that has a remote monitoring and control function and can be operated directly as a backup for the remote monitoring function, and a protection control panel with independent protection functions for each bank, and the distribution control panel and protection control panel function together as a substation distribution panel.

[0022] Figure 2 shows an example of the configuration of the substation switchboard, which, as mentioned above, is composed of a distribution control panel and a protection control panel. The distribution control panel is equipped with units with monitoring and control functions, and switches that directly control each device in the substation and extra-high voltage equipment. The units are equipped with a direct display unit that collects information from each unit and displays and issues warnings, an IP-TC unit that consolidates information from each unit and transmits the information to the power supply control center system, which is a higher-level device, and receives selection control commands from the higher-level device, and a remote control unit that receives selection control commands from the above units and controls the equipment. In addition to these, it is equipped with an expansion unit that implements a common display function for monitoring each device in the substation, an automatic power receiving switching function, and a reverse power flow detection function.

[0023] In addition to the power supply units, the protection control panel is equipped with protection units with protection functions for each protection range, and protection and control units that have control functions in addition to the above protection functions. Examples of units installed include a bank protection LR control unit that performs voltage adjustment through main transformer primary and earth fault backup protection and tap control, a transformer protection unit that protects the transformer by disconnecting it from the transmission line when an abnormality occurs in the transformer, and bus protection units (A bus protection unit, B bus protection unit) that protect the main transformer secondary and switching busbars.

[0024] A PC can be connected to the protection control panel as a monitoring computer, which can monitor the status of each unit in real time, collect and analyze data, display program numbers, and manage that the program is correct.

[0025] In addition, the substation switchboard having the configuration shown in FIG. 2 can be remotely monitored and controlled from the power supply control center via a distribution remote monitoring and control device (IP-TC).

[0026] The protection control panel according to the present invention has a technical feature in that, when the polarity of the instrument transformer on the primary or secondary side of the transformer is incorrectly connected, a warning is displayed on the transformer protection unit without the need to check the calculation results of the digital protection relay (e.g., ratio differential current relay) and measurement function implemented in the transformer protection unit on the computer connected to the protection control panel. The warning display is assumed to be a warning light or a display showing text information.

[0027] As with conventional methods, incorrect polarity connections of instrument transformers are checked by passing a test current through the transformer protection unit in the protection control panel. The protective relay and measurement function detect the incorrect connection from the phase difference and current value between the primary and secondary currents of the transformer, and display a warning on the transformer protection unit.

[0028] As a result, by checking the warning display, an operator can quickly and reliably check for incorrect connection of the polarity of the instrument transformer. If an incorrect connection is discovered, it is possible to prevent the circuit breaker from opening due to the incorrect connection by reconnecting the polarity correctly.

[0029] In other words, according to the present invention, there is no need to connect a confirmation computer to the protection control panel to check for incorrect connection of the polarity of the instrument transformer, thereby reducing the burden on the worker.

[0030] Another advantage is that it can distinguish and detect insulation breakdown accidents caused by external accidents or internal faults in the transformer, accidents caused by overload, and incorrect polarity connections in the instrument transformer.

[0031] As described above, according to the protection and control panel of the present invention, incorrect polarity connection of an instrument transformer can be easily confirmed without connecting a monitoring computer to the protection and control panel, thereby reducing the burden on workers. [Industrial Applicability]

[0032] The present invention is applicable to a transformer protection unit that constitutes a substation switchboard.

Claims

[Claim 1] A protective control panel constituting a distribution board which monitors, controls and protects the equipment, busbars and distribution lines of a substation, is installed to detect the current values ​​on the primary and secondary sides of a transformer constituting a substation, and in the event of an incorrect connection of the polarity of an instrument transformer connected to a protective relay installed in the protective control panel, the protective control panel detects the incorrect connection from the phase difference and current value between the primary and secondary sides and displays a warning on the protective control panel.

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