RU194840U1 - Microprocessor-based relay protection device against arc faults - Google Patents

Abstract

The utility model relates to the field of electrical engineering and the electric power industry, in particular to a microprocessor-based relay protection and automation device (MPD) of electrical installations with a voltage of 6-35 kV. The microprocessor-based device for relay protection against arc faults contains a housing in which the following are connected by a common data bus: indication unit (BI); a microprocessor unit containing at least one processor that performs computational processing (BM); block of discrete inputs and outputs (BDVV); block of transformers (BT); power supply unit (PSU); in this case, four channels are made in the case, which are self-diagnosed inputs with the possibility of connecting optical arc sensors to them, while each of the self-diagnosed inputs contains a connector for a receiving element and a connector for a radiating element. The utility model allows to expand the functionality of the device by expanding the functional composition, reducing the number of external connections of the device, for example with an external device for recording arc faults. This simplifies and increases the reliability of the circuit. The ability to connect sensors such as fiber-optic sensors with diagnostics of the integrity of the optical fiber increases reliability and provides galvanic isolation. The presence of measuring current circuits allows you to perform additional control of arc faults by current. 2 ill.

Description

The prior art microprocessor relay protection device against arc faults (see [1] patent for utility model of the Russian Federation No. 49386, IPC H02H 3/00, publ. 10.11.2005), containing five registers, a decoder, a block of elements and two elements NOT, a command generation block, n-input nodes, a switch, two bus shapers, a blocking node and m-relays with m-resistors.

The disadvantage of this analogue is the use of two types of external auxiliary devices for detecting arc faults, the lack of integrity diagnostics of both the fiber optic (VOD) and photothyristor sensors (FTDs), and the lines connecting them to the microprocessor unit. It should also be noted that the processing of signals from the VOD and FTD is performed by different microprocessors, which reduces reliability by increasing the number of circuit components.

The closest analogue of the claimed utility model adopted as a prototype is a microprocessor-based relay protection and automation device (MPD) (see [2] RF patent No. 2645750, IPC H02H 7/00, publ. 02.28.2018), comprising a housing, in which are installed united by a common data bus: a processor module containing one or more processors that performs the main computing processing and a real-time clock module; a memory unit containing ROM and RAM; communication interfaces configured to communicate with external computing devices; protective relay automatics (RZA) modules connected to the processor module and including measurement modules consisting of an analog input module and a digital input module, a relay module, which is a digital output module, and a combined digital input / output module; a power supply unit configured to maintain the operability of the device in case of loss of operational power; moreover, the analog input module contains an ADC designed to convert incoming analog signals, contains galvanically isolated input channels and is used to measure currents and voltages in three phases and zero sequence; a front panel connected via a USB communication interface to the processor module, the front panel comprising a microcontroller, communication interfaces with external computing devices, a display, LEDs, a keyboard and a front panel are removable with the possibility of remote control of MPD.

The disadvantages of the prototype are the lack of external auxiliary devices for recording arc faults, as well as the presence of a front panel and keyboard connected via USB, which reduce reliability and ease of use.

Utility Model Essence

The objective of the claimed utility model is the relay protection function of electrical installations with a voltage of 6-35 kV.

The technical result is to expand the functionality of the device by expanding the functional composition, reducing the number of external connections of the device, for example, with an external device for recording arc faults.

The problem is solved, and the technical result is achieved due to the microprocessor device for relay protection against arc faults, containing a housing in which are installed united by a common data bus: indication unit (BI); a microprocessor unit containing at least one processor performing computational processing (BM); block of discrete inputs and outputs (BDVV); block of transformers (BT); power supply unit (PSU); while in the housing there are four channels connected to the microcontroller, the channels are self-testable inputs with the possibility of connecting optical arc short circuit sensors to them, while each of the self-testable inputs contains a connector for a receiving element and a connector for a radiating element.

Brief Description of the Drawings

Figure 1 shows the structural diagram of a microprocessor device.

Figure 2 shows a microprocessor device from two sides.

The following positions are indicated in the figures:

pos. 1 - power supply; pos. 2 - block transformers; pos. 3 - microprocessor unit; pos. 4 - block of discrete inputs and outputs; pos. 5 - display unit; pos. 6 - case; pos. 7 - receiving element; pos. 8 - radiating element; pos. 9 and 11 - contact groups of a block of discrete inputs and outputs; pos. 10 - contact group transformer unit.

Utility Model Implementation

The technical result is achieved by the fact that in the microprocessor device, which is a device for relay protection and automation, four channels are implemented, which are self-diagnosed inputs for connecting optical arc short circuit sensors. The sensors are intended for installation in places of possible occurrence of arc faults, at power facilities, such places are devices containing switching elements - high-voltage cells, which are one of the elements of a complete switchgear. High-voltage cells are structurally divided into compartments: the input / output compartment (cable), the draw-out element compartment (switch), the busbar compartment. Arc faults, depending on the emergency mode, can occur in each of the listed compartments. The increased number of inputs (4 inputs) for connecting optical sensors provides the ability to install the sensor in each compartment of the high-voltage cell, thereby monitoring and protecting the entire cell.

The microprocessor-based device for relay protection against arc faults contains a housing (pos. 6), in which the following are connected by a common data bus: indication unit (BI) (pos. 5); a microprocessor unit (item 3), containing at least one microcontroller that performs computational processing (BM); block of discrete inputs and outputs (BDVV) (item 4); block of transformers (BT) (item 2); power supply unit (PSU) (item 1). At the same time, four channels are made in the case (pos. 6), which are self-diagnosed inputs with the possibility of connecting optical arc short sensors to them (not shown in the figures), while each of the self-diagnosed inputs contains a connector for the receiving element (pos. 7) and a connector for the radiating element (pos. 8).

The power supply unit (pos. 1) converts the operational power voltage to the voltage necessary to power the volatile units: BM (pos. 3), BDVV (pos. 4), BI (pos. 5). The transformer unit (pos. 2) is non-volatile and converts the sinusoidal AC signals supplied to it into alternating current voltage and transfers it to the microprocessor unit (pos. 3). The block of discrete inputs and outputs (pos. 4) compares the levels of AC or DC voltage signals supplied to it with a given level and converts it into discrete logic signals, transmitting these values to the BM (pos. 3). BDVV (pos. 4) also receives logic signals “zero” and “one” from the BM (pos. 3) and turns off or turns on the miniature electromechanical relays available in this unit, providing switching of external circuits connected to the contact group (pos. 9 ) BM (pos. 3), receiving AC voltages from the BT (pos. 2), processes them using the ADC, and with the help of mathematical and logical operations performed by the microcontroller (included in the BM), sends logic signals to the BVVV (pos. 4) to enable or disable the relay. BM (pos. 3) receives optical signals to the receiving elements (pos. 7) converts them into logical signals “zero” and “one” and performing logical operations taking into account the signals from the BT (pos. 2) and BVVV (pos. 4) , transmits logical signals to the BDVV for turning the relay on or off and to the BI (pos. 5) for displaying on the liquid crystal display or LEDs. BM (pos. 3) using radiating elements (pos. 8) transmits test pulses to fiber optic sensors (not shown in the figures) and receives them at the receiving element (pos. 7), thereby monitoring the integrity of the fiber optic sensors.

The device operates as follows.

The utility model responds to spark discharges and is triggered before the appearance of a column of an electric arc, or, in extreme cases, at the initial stage of the moment of arc appearance. As a result, equipment damage is minimized or eliminated, and the safety of maintenance personnel is also ensured. The utility model performs the following functions: protection against the occurrence of an electric arc, through its recognition, and the issuance of a control signal; internal self-diagnosis of the integrity of the arc sensors and microcircuits; protection against false alarms in the event of pulsed electromagnetic interference of high power, as well as from extraneous light sources, such as a flashlight, incandescent lamps, sunlight. The receiving element is selected in such a way that the spectrum of its maximum sensitivity does not coincide with the spectra of the maximum radiation of extraneous light sources. Thus, radiation from extraneous light sources does not create voltage levels sufficient for operation in the receiving element. The receiving element (pos. 7) is a photodiode that converts an optical signal into an electric one. The transmitting (radiating) element (pos. 8) is an LED that converts test electrical pulses from the microcontroller to optical ones.

Up to four arc sensors are connected to the device - according to the number of possible enclosed cell volumes of a complete switchgear (KRU), a complete switchgear of an outdoor installation (KRUN) or a prefabricated one-way service chamber (KSO). The switchgear consists of compartments separated by metal partitions, necessary for the safe performance of work inside the switchgear and to limit equipment damage during arc internal circuits. Switchgear can contain from three to four compartments. For greater reliability, it is possible to install several arc sensors in one compartment. Protection against arc faults is intended to disconnect the protected connection in case of an arc fault in the input / output compartment (cable) and the formation of the ZDZ bus during arc faults in the switch compartment. The ZDZ bus is connected to the contacts of all arc protection devices located in other switchgear cubicles and designed to exchange logical signals between arc protection devices, relay protection and their selective operation. The ZDZ action on tripping is carried out only with arc faults in the input / output compartment (cable), since in this case the tripping of the circuit breaker can prevent the further spread of the emergency mode without disconnecting the entire bus section. In order to exclude improper operation of the ZDZ during false positives of the ZDZ sensors, the shutdown effect can be controlled by the starting organs of the maximum current protection and the starting voltage organs. In case of false positives of the sensors for protection against arc faults, it can be monitored by the starting organs, which allows you to monitor the health of the sensor for protection against arc faults.

The device contains four self-testable inputs for connecting optical arc short sensors. The input, purpose and sensitivity of the inputs is determined by the settings. The action of each channel is determined by an individual setting having 4 positions:

Disabled - disabled, the action on the switch or section is excluded;

To the switch - to the switch, the operation of the sensor generates a signal that acts to trip its own switch;

Per section - per section, the sensor triggers a signal that acts to disable the section;

To the switch and section - to the switch and section, the operation of the sensor generates signals to trip the switch and section.

The function of protection against arc faults in the device can operate both from external arc fault recorders and from its own.

The optical arc sensor is a photosensitive element made of a sheathed polymer fiber. The fiber is connected via connectors to the fiber optic communication cable, which is connected to a microprocessor device using self-diagnosed inputs.

In the presented device, operational monitoring of the operability of optoelectronic channels is implemented by testing the device. Operational monitoring of the operability of optoelectronic channels is carried out by the device testing system. The device once every 40 seconds in the operating mode and 10 times per second in the testing mode generates and records the passage of the optoelectronic signal. During the passage of the test pulse, false alarms of the device are eliminated. The optoelectronic signal is generated by the control LEDs of the device. A working sensor must pass a pulse to the receiving photodiode. If the value of the receiving pulse is less than the threshold value, a fault signal is issued.

Protection against arc faults in the device can be used with external arc protection devices, in this case, signals from sensors installed in the input / output compartment (cable) are fed to digital inputs. The triggered state of the sensors in the compartment is indicated by the light-emitting diodes on the front panel of the device.

Principle of operation: Fiber optic, fiber optic sensors fix a bright light flash from an electric arc by their side surface. Further, this signal is transmitted via a fiber optic communication cable to a photoelectronic converter-photodiode, which converts the optical signal into an electrical one. The signal is amplified and fed to the microcontroller. The signal amplitude is compared with the threshold level of the device. When this level is exceeded, the device operates and generates a shutdown signal with the help of electromechanical relays, which is sent to the switch installed in the cell or to the higher-level switches. The switch on this signal produces the corresponding effects of cutting off the power supply to the damaged cell or section of the substation to prevent further spread of the electric arc.

The claimed microprocessor device is a single device implemented in one housing.

Due to the claimed essential features of the utility model, the functionality of the device is expanded by expanding the functional composition, reducing the number of external connections of the device, for example, with an external device for recording arc faults. This simplifies and increases the reliability of the circuit. The ability to connect sensors such as fiber optic sensors with diagnostics of the integrity of the optical fiber increases reliability and provides galvanic isolation. The presence of measuring current circuits allows for additional control of arc faults by current.

Claims (2)

A microprocessor-based device for relay protection against arc faults, comprising a housing in which a common data bus is installed: indication unit (BI); a microprocessor unit containing at least one processor that performs computational processing (BM); block of discrete inputs and outputs (BDVV); block of transformers (BT); power supply unit (PSU), while in the housing there are four channels connected to the microcontroller, the channels are self-testable inputs with the possibility of connecting optical arc short circuit sensors to them, while each of the self-testable inputs contains a connector for a receiving element and a connector for a radiating element.

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