RU2265860C1 - Device for checking condition of three-phase equipment having capacitor-type paper-oil insulation - Google Patents

Abstract

FIELD: test equipment.

SUBSTANCE: device has several units for conducting signal preliminary processing connected in parallel to final data processing unit through communication line. Device also has signaling unit. Final data processing unit has operator's PC and data collecting unit made on the base of industrial computer. Preliminary data processing unit has units for connecting object to measuring terminals of phases, commutation unit, a alarm protection unit and measuring unit. The latter has analog signal preliminary processing unit provided with primary converters on the base of precision resistors, analog signal basic processing unit, digitization unit and communication interface. Device performs continuous centralized inspection of capacitor-type paper-oil equipment (high-voltage terminals, current transformers) to detect leakage in insulators at early stage without switching equipment off.

EFFECT: improved reliability of operation.

4 cl, 7 dwg

Description

The invention relates to a technique for diagnosing high voltage electrical equipment and is intended for continuous monitoring of equipment with paper-oil insulation of a capacitor type (high voltage bushings, current transformers) with a rated voltage of 110 kV and higher.

A device for automatically monitoring the state of insulation of high-voltage equipment (AS No. 296062, IPC G 01 R 31/02, G 01 R 31/08,) comprising an input adder block of two adders that sums the currents of two monitored objects, measuring and signal units, which included in the difference of the output currents of the adders. To control two heterogeneous three-phase objects, the adders are equipped with adjustable regulators during commissioning.

A device is also known for automatic monitoring of the insulation state of high-voltage equipment (AC N 384080, IPC G 01 R 31/12), which in addition to the device according to AC N 296062 contains three resistances, each of which is connected between the adder and the corresponding phase of the controlled network through a voltage transformer .

Closest to the proposed solution is a control system for insulation of high-voltage bushings (RF patent No. 2145420, IPC G 01 R 31/08, G 01 R 31/12), containing devices for connecting to three-phase high-voltage bushings, the outputs of which are connected to the inputs of the corresponding instrument transformers current, a voltage transformer of a three-phase high-voltage bus system, the outputs of which are connected to the inputs of the corresponding instrument voltage transformers, an alarm device, two phase shifters connected to the outputs of two of the three instrument transformers torus currents, ADC and microprocessor.

The disadvantage of these devices is the impossibility of centralized monitoring with data archiving, the impossibility of determining false alarms, as well as the use of a current transformer in these devices, which complicates their operation due to the need for periodic verification.

The objective of the proposed solution is continuous centralized monitoring of condenser-type paper-oil equipment (high voltage bushings, current transformers) in order to detect leaks in insulators at an early (pre-emergency) stage without shutting down this equipment.

The problem is solved in that a device for monitoring the state of paper-oil inputs of high-voltage three-phase equipment, containing connected signal pre-processing, signal final processing and signaling units, while the signal pre-processing unit includes elements for connecting the object to the phase measurement inputs connected to the measuring unit containing primary converters connected to an analog signal preprocessing unit and a digitizing unit, according to but to the solution, it contains a communication interface in the measuring unit connected to the digitizing unit, and the signal final processing unit contains a personal computer and an information collection unit based on an industrial computer, one output of the information collection unit is connected to a personal computer, and the second to the signaling device, while the input is connected to the signal preprocessor via a communication line, and precision resistors are used as primary converters.

The device contains a main analog signal processing unit, connected between the pre-processing unit by the digitizing unit, and it consists of three adjustable amplifiers with separate gain control for each phase, connected to a series-connected switching adder and a normalizing amplifier. The digitization block is made in this case single-channel. This embodiment allows you to minimize the digital stream on the communication line.

The device further comprises several signal preprocessing units connected in parallel to the communication line.

The device further comprises a switching and emergency protection unit, comprising in the circuit of each phase of the jumper connecting the input signal, parallel and grounded gas dischargers, resistors and contactors, located between the connection elements and the measuring unit.

The invention is illustrated by drawings, in which Fig. 1 is a block diagram of the device as a whole, in Fig. 2, in Fig. 3 is a vector diagram, in Fig. 4 is an equivalent circuit of a high voltage input, Fig. 5 is a circuit diagram of one BKAZ channel 6 is a functional diagram of a measurement unit, FIG. 7 is a block diagram of a main analog processing unit, where:

1 - signal preprocessing unit (BPOS)

2 - block final signal processing (BOOS)

3 - signaling device

4 - elements of the connection of the object (EPO)

5 - measurement unit (BI)

6 - information collection device (USI)

7 - personal computer (PC) operator

8 - switching unit and emergency protection (BKAZ)

9 - jumper

10 - gas spark gap

11 - resistor

12 - contactor

13 - precision resistor

14 - block pre-processing of the analog signal (BPOAS)

15 - the main unit for processing an analog signal (OBOAS)

16 - block digitization (BO)

17 - communication interface (IP)

18 - adjustable amplifiers

19 - switched adder

20 - normalizing amplifier

21- digital filter

Sd1, Sd 2 - equivalent input capacitance

R _ut - leakage resistance

Each set of BPOS 1 includes elements for connecting the object EPO 4, the switching unit and emergency protection BKAZ 8 and the measuring unit BI 5.

Elements for connecting the object EPO 4 performs the function of attaching the measurement leads of the high-voltage bushings to the input terminals BKAZ 8.

The switching unit and emergency protection BKAZ 8 is designed to connect the measuring path of the BPOS kit 1 to the connection elements of the EPO 4, the implementation of the first stage of emergency protection, the allocation of the input voltage to the element of the measuring resistor 11 (which in this case is part of the measuring resistor 13 BI 5) and supply input voltage to the measuring unit BI 5. In addition, BKAZ 8 provides grounding of the input phase lines to ensure safety when working with BI 5. EPO 4 elements can be connected directly to the BI 5 block u, but in this case the functions listed above are excluded.

The BI 5 measurement unit performs the function of finally isolating the measured voltage at the BI 5 resistor (including the 2nd and 3rd steps of measuring path protection), processing the analog signal to the required level, switching phase signals in accordance with the specified measurement mode, suppressing the third harmonics of the network frequency, digitizing the signal into code packets and transmitting information to the communication line with the USI 6. BI 5 performs a two-way exchange of information with the USI 6, managing BI 5 operating modes by command with USI 6 or from PC 7 through USI 6 and providing the necessary information to the communication line.

The device operates as follows:

The voltages from the measuring plates of the inputs of the controlled equipment are fed through the connection elements of the EPO 4 to the input of the BKAZ 8. Then they pass into the measuring path through the jumpers 9 corresponding to each phase. Gas dischargers 10 form the first stage of protection of the measuring path. The switch 12 in the working position is open, but closes the phase lines to the ground to ensure safety during preventive maintenance with BI 5. The precision measuring resistor, which is the primary measuring transducer, is structurally divided into 2 parallel-connected resistors 11 and 13, one of which is in the BI 5, and the other (11) is issued in BKAZ 8, to improve reliability and safety. Separation of the BKAZ 8 into a separate unit allows disconnecting jumper 9 to connect measuring instruments to the measuring output of the high voltage input during the prevention of high voltage equipment without raising personnel to high located high voltage inputs, or to perform BPOS prophylaxis by applying test signals to the inputs of the phase measuring channels after jumper 9. Voltages from BKAZ 8 through a 4-wire cable (phases A, B, C and 0) are supplied to BI 5, to the input of the pre-processing unit of the analog signal 14, consisting of yazheniya each phase, the second element of the measuring resistor 13, and the switched voltage divider terminal protection stages (not shown) to prevent ingress of measuring electronics inputs interference voltages and interference dangerous levels.

The phase voltages coming from the pre-processing unit of the analog signal 14 are fed to the main processing unit of the analog signal 15, where they are fed to adjustable amplifiers (not shown in the drawing), the transmission coefficients of which are set by command from an operator PC 7. These adjustable amplifiers are used to initial balancing of phase voltages. Further, from the outputs of the regulated amplifiers of phases A, B, C through the switches controlled from the controller of the digitizing unit 16, the voltage passes to the output of the switched adder 19. The voltage of the adder signal is supplied to the normalizing amplifier 20, the transmission coefficient of which is determined by commands from the controller depending on the measurement mode . The signal amplified or attenuated to the required level passes through a digital filter 21, which attenuates the 3rd harmonic of the network frequency by at least 1000 times and excludes its influence on the measurement result.

Next, the signal from the main processing unit of the analog signal 15 is fed to a single-channel digitizing unit 16 containing a module for converting the analog signal to digital and microcontroller.

Between the controller and the communication line there is a bi-directional communication interface 17, which provides galvanic isolation and coordination of the signal levels of the controller with the level of the communication protocol in the communication line.

Management of the operating mode is carried out from the PC operator 7 through the upper level program.

USI 6 processes the data from all sets of BOS 1, stores it in a database and communicates with the personal computer of operator 7. In addition, USI 6 generates a signal to trigger an external light or sound alarm device 3 according to the criteria specified from the keyboard of the operator PC 7.

This device provides software and hardware for continuous monitoring of data from control points by the nonequilibrium-compensation method, based on measuring the time changes of previously (at the initial stage) balanced complex leakage currents. The main part of the analog signal processing algorithm is implemented in hardware in the main block for processing the analog signal 15.

With good quality high-voltage input (leakage current through R _{ut is} negligible) and the equality of the modules of the phase vectors, the sum of the three phases is 0 (Fig.2).

When a noticeable value of R _ut appears, the phase angle changes and, accordingly, the sum of the vectors U _sum becomes nonzero (Fig. 3).

Measuring in turn modules of unit vectors, modules of the sums of two vectors, and the module of the sum of three phase vectors, the device determines the change in the complex conductivity of the measuring capacitive divider using the USI software and, according to the criteria for leakage stored in the computer memory, the suitability of this input for further operation is determined.

In order to detect the difference in the “drawdown” of the voltage of one phase due to the uneven load from the change in the phase vector module due to leakage in this input, the computer compares the readings of different sets of BPOS connected to the same phase, thus producing a normalization criterion voltage of this phase.

To increase reliability and maintain metrological stability, measurement units operating in the open air are equipped with a heating device that automatically maintains a positive temperature in the BI case in the cold season.

The USI of this device allows, in addition to the main alarm device, to connect an additional up to 7 signaling devices.

This device allows, in addition, using the local area network (LAN) of the enterprise, to connect to the SII, in addition to the operator’s PC, the personal computers of the responsible persons of the enterprise.

User software options leading to changes in device parameters are password protected.

Claims (4)

1. A device for monitoring the state of three-phase equipment with paper-oil insulation of a capacitor type, comprising connected signal pre-processing, signal final processing and signaling units, while the signal pre-processing unit includes elements for connecting the object to phase measurement inputs connected to a measuring unit containing primary converters connected to an analog signal pre-processing unit and a digitizing unit, characterized in that it contains in the measuring unit, the communication interface is connected to the digitizing unit, and the signal final processing unit contains a personal computer and an information collection unit based on an industrial computer, one output of the information collection unit is connected to a personal computer, and the second to the signaling device, while the input is connected to signal preprocessing device over the communication line, and precision resistors are used as primary converters. 2. The device according to claim 1, characterized in that it further comprises a main analog signal processing unit included between the analog signal preprocessing unit and the digitizing unit, while it consists of three adjustable amplifiers with separate gain control for each phase, connected to sequentially connected by a switched adder and a normalizing amplifier, while the digitizing unit is single-channel. 3. The device according to claim 1, characterized in that it further comprises several signal preprocessing units connected in parallel to the communication line. 4. The device according to claim 1, characterized in that it further comprises a switching and emergency protection unit located between the connection device and the measuring unit, the unit comprising input signal jumpers connected to each phase with parallel connected and grounded gas spark gap, a resistor and contactor.

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