RU96448U1 - DEVICE FOR INSULATION RESOURCE CONTROL - Google Patents

Abstract

 1. A device for monitoring the insulation resource of high-voltage electrical equipment, containing an analog-to-digital conversion unit connected to the system bus, the input of which is designed to connect to a voltage sensor, a data output unit and a digital processing unit, programmed to store the current value of the consumed insulation resource, comparing modules instantaneous voltage values counted by the analog-to-digital conversion unit at time intervals of a given duration, with nom the total magnitude of the amplitude voltage on the electrical equipment, the identification of overvoltages, finding a value that inversely depends on the allowable duration of exposure of each detected overvoltage, and adding it to the current value of the consumed insulation resource. ! 2. The device according to claim 1, characterized in that it is arranged to count the time of absence of the indicated excesses and subsequently periodically subtract the set value of the resource from the current value of the consumed isolation resource if the counted time exceeds a predetermined time.

Description

Technical field

The utility model relates to the electric power industry and, in particular, to means for automatically controlling the insulation resource of high-voltage electrical equipment during its operation.

State of the art

The insulation resource of high-voltage electrical equipment is currently regulated by the interstate standard GOST 1516.3-96 “Electrical equipment of alternating current for voltages from 1 to 750 kV. Requirements for dielectric strength ”. The standard, in particular, establishes a correspondence between each of several fixed relative values of overvoltages (i.e., voltage values exceeding the nominal value taken as 1.0) and fixed values of the maximum allowable durations of exposure of these overvoltages to the insulation of electrical equipment and, thereby , determines the intensity with which the insulation resource is consumed under the influence of overvoltages of various degrees.

A device for automatically controlling the consumption of the resource of insulation of electrical equipment in accordance with the specified standard [patent RU 2145760, IPC Н02Н 9/04, 9/08, 2000], selected as a prototype. The prototype device is made on discrete elements of digital technology with the ability to determine each half-period of industrial frequency the amplitude (i.e. maximum half-period) voltage value on electrical equipment, compare the measured voltage with several fixed values of overvoltage, for each of them calculate the resource consumption, summing the numbers determined by the permissible duration of exposure of the larger of the exceeded fixed values of overvoltages, and to determine the total spent resource isolation, summing up the numbers accumulated separately for each of the exceeded fixed values of overvoltages.

The disadvantage of the prototype is the low reliability of the control of the consumed isolation resource. There are two reasons for this.

The first of these is as follows. According to Table B.2 of the specified standard, which lists eight fixed values of overvoltage, the permissible overvoltage depends heavily on the magnitude of the relative overvoltages (for example, for power transformers, when the relative overvoltage changes from 1.025 to 1.25, its allowable exposure duration varies from 8 hours to 20 seconds respectively). Therefore, a comparison of the measured overvoltages with only a few fixed overvoltages (for example, with those given in the specified table of the standard) and, as a result, the choice of one value of the permissible exposure duration for all overvoltages falling in the interval between two standardized values, is accompanied by significant errors.

Another reason for the low reliability of the control performed according to the prototype is that in the prototype, only one (maximum per half-period) value of the measured voltage is measured and compared with the nominal amplitude value and characterize the intensity of the consumption of insulation resource over the entire half-period. Overvoltages are often accompanied by distortion of the sinusoidal voltage form and the appearance of short-term surges exceeding the amplitude value of the sinusoidal voltage. The presence of such surges must be taken into account when determining the consumed insulation resource, however, the prototype takes into account only one (maximum per half-period of industrial frequency) surge, the magnitude of which sets the intensity of consumption of the insulation resource over the entire half-period.

As a result, the prototype gives only a rough, rough estimate of the consumed resource and in order to guarantee the reliable operation of electrical equipment, it is necessary to operate it with a shortened overhaul period.

The objective of the utility model is to eliminate this drawback.

Utility Model Disclosure

The technical result of the utility model is to increase the reliability of control of the consumed insulation resource and, accordingly, the ability to more fully use the existing resource of electrical equipment without compromising operational reliability.

The subject of the utility model is a device for monitoring the insulation resource of high-voltage electrical equipment, containing an analog-to-digital conversion unit connected to the system bus, the input of which is designed to connect to a voltage sensor, a data output unit and a digital processing unit programmed to store the current value of the consumed insulation resource, comparing the modules of instantaneous voltage values counted by the analog-to-digital conversion unit over time intervals They are of a given duration, with a nominal value of the amplitude voltage on the electrical equipment, detecting overvoltages, finding a value that inversely depends on the permissible duration of exposure of each detected overvoltage, and adding it to the current value of the consumed insulation resource.

This provides the above technical result.

A useful model has a development, which consists in the fact that the device is capable of counting the time of absence of the indicated excesses and subsequent periodic subtraction of the specified value of the resource from the current value of the consumed insulation resource if the counted time exceeded the specified one.

This allows you to take into account the recovery processes that occur in isolation with a prolonged absence of overvoltage.

Utility Model Implementation

Figure 1 shows the structural diagram of the inventive device, made on the basis of a programmable microprocessor controller, figure 2 is a block diagram illustrating the implementation of the inventive device functions to control the insulation resource, figure 3 is an example of the dependence of the allowable duration of the overvoltage on its value.

The structural diagram in figure 1 contains connected to the system bus 1 ("common bus"):

- block 2 analog-to-digital conversion;

- block 3 (programmable) digital processing;

- block 4 data output;

Secondary phase voltages from a voltage measuring transformer installed on high-voltage electrical equipment, for example, power lines, are connected to the inputs of block 2.

The device operates as follows.

Block 2 converts each of the secondary phase voltages into digital samples for further digital processing in block 3.

Block 3 receives data from block 2 through the system highway 1 and processes it and stores in memory the current value of the consumed isolation resource, which is transmitted to block 4 along the same highway 1.

In the course of data processing, unit 3 compares with the nominal magnitude of the amplitude voltage on the controlled electrical equipment the modules of samples (i.e., measured instantaneous voltage values) coming from unit 2 at time intervals of a given duration. In this case, it reveals the excess of the instantaneous voltage value over the nominal value of the amplitude, i.e. overvoltage on controlled electrical equipment.

For each detected overvoltage, block 3 calculates a value that is inversely dependent on the allowable duration of its exposure, and increases by this value the current value of the consumed isolation resource stored in memory.

Taking into account the development of the utility model, block 3 can be additionally programmed to perform the following functions: counting the time of absence of overvoltage, comparing this time with the given one, and then periodically subtracting the given value from the current value of the consumed resource if the counted time exceeded the specified one.

Block 4 provides data on the current value of the insulation resource to inform personnel and / or in the automatic control system of controlled electrical equipment.

The flowchart in figure 2 illustrates in detail the process by which the claimed device performs the above functions. Figure 2 shows the block 2 analog-to-digital conversion and functional blocks 5-12, reflecting the sequence of data processing carried out by block 3.

Block 5 in figure 1 is equipped with a vertical arrow, illustrating its launch at time intervals, the duration of which is at least an order of magnitude less than the period of industrial frequency.

At these time intervals, block 5 receives digital samples from block 2 and compares their modules with the nominal amplitude of the sinusoidal voltage on the controlled electrical equipment. If the nominal amplitude is exceeded, the module of this reference is recorded as an overvoltage, and its value is output to block 6. In cases where the nominal amplitude is not exceeded (i.e. there is no overvoltage), the signal to the output of block 5 is not received.

Block 6 determines the relative consumption of the insulation resource, proportional to the intensity of the resource consumption in the interval Δt of a given duration (processing interval in block 5), as a value inversely dependent on the allowable duration T _i of the overvoltage effect, the value of which is obtained from block 5 on the i-th processing interval , in the following way.

In the memory of the microprocessor controller is stored (in the form of a detailed table of digital values) the dependence of the allowable exposure duration on the magnitude of the overvoltage obtained by interpolating the corresponding data given in the above standard (see figure 3). Choosing from the specified table a digital value of the duration corresponding to the overvoltage value received from block 5, block 6 finds the allowable duration of the effect of this overvoltage.

Then he calculates the intensity of the consumption of the insulation resource under the influence of overvoltage, as the reciprocal of the found allowable exposure duration and gives its value to block 7.

Since the duration of the time intervals through which block 5 is started is significantly less than the period of the industrial frequency, we can assume that the voltage on the electrical equipment, and therefore the intensity of the consumption of the insulation resource for one such interval, does not practically change. The value of the resource consumed during this interval is proportional to the calculated flow rate intensity and can be immediately obtained from the table if, instead of the allowable exposure durations, inverse values are stored in it. At the same time, the proportionality coefficient used to calculate the consumed resource only scales the calculations and can be selected for convenience.

Received by block 7, the value of the consumed resource is then added by the adder 8 to the current value of the consumed isolation resource P, which is stored in cell 9 of the memory of block 3.

The above operations are performed on relative values: the voltage values can be processed, for example, in the form of their relation to the nominal value of the amplitude voltage, and the values of the consumed insulation resource - in the form of fractions of the total insulation resource, conventionally taken as a unit. In this way

In the absence of overvoltage for a sufficiently long time, the insulation resource is gradually restored. Based on this insulation property, the utility model provides for development, which can be carried out as follows. The timer 10 is reset when block 5 outputs to block 6 data on each overvoltage. In the absence of such zeroings (i.e., in the absence of signals about overvoltage), the timer 10 after a specified time is activated and starts the block 11, which with the help of the adder 8 periodically subtracts the predetermined relative values from the current relative value of the consumed insulation resource stored in the cell 6 memory microprocessor terminal. When this value reaches zero, a signal appears at the output of the zero value decoder 12, which arrives at the inverse input of block 11 and stops it.

Data on the current value of the consumed insulation resource stored in cell 9 and on the exhaustion of the insulation resource can be used to automatically control the operating voltage on the controlled equipment (for example, to compensate for capacitive overvoltages on a power line by connecting shunt reactors and removing voltage from equipment that has exhausted isolation resource) and / or to inform staff.

Using the proposed utility model allows to increase the reliability of control of the consumed insulation resource and thereby extend the overhaul period of electrical equipment maintenance without reducing its reliability.

Claims (2)

1. A device for monitoring the insulation resource of high-voltage electrical equipment, containing an analog-to-digital conversion unit connected to the system bus, the input of which is designed to connect to a voltage sensor, a data output unit and a digital processing unit, programmed to store the current value of the consumed insulation resource, comparing modules instantaneous voltage values counted by the analog-to-digital conversion unit at time intervals of a given duration, with nom the total magnitude of the amplitude voltage on the electrical equipment, the identification of overvoltages, finding a value that inversely depends on the allowable duration of exposure of each detected overvoltage, and adding it to the current value of the consumed insulation resource. 2. The device according to claim 1, characterized in that it is arranged to count the time of absence of the indicated excesses and subsequently periodically subtract the specified value of the resource from the current value of the consumed isolation resource if the counted time exceeds a predetermined time.