RU205634U1 - DEVICE FOR COMPENSATION OF THE INDUCED VOLTAGE AT THE PLACE OF WORK PRODUCTION ON THE DISCONNECTED POWER LINE - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used in the electric power industry to ensure the safety of work on disconnected power lines that are under induced voltage. The technical result is to ensure the safety of work on overhead power lines (OHL) by reducing the induced voltage at the work site to safe values with the help of the Induced voltage compensation device.

Description

Technical field to which the utility model belongs

The utility model relates to devices in the field of electrical engineering and can be used in the electric power industry to ensure the safety of workers when working on disconnected power lines under induced voltage.

State of the art

It is known that the induced voltage on a disconnected overhead line occurs as a result of the action of electromagnetic fields of operating overhead lines passing near the disconnected overhead line. The value of the induced voltage depends on the operating voltage of the influencing overhead lines, the magnitude of the current in them, the grounding resistance, the length of the parallel path, the relative position of the wires and a number of other factors. The influence of neighboring parallel overhead lines can be considered as the sum of the electrical and magnetic components. The electrical (transverse) component on an ungrounded overhead line can reach several thousand volts. The electromagnetic (longitudinal) component leads to the appearance of a touch voltage at the work site, caused by the spreading of the induced current along the ground through the grounding at the work site. Grounding the overhead line at least at one point leads to almost complete disappearance of the transverse component. If there is a steady normal mode on the operating line, then the induced voltage at the place of work on the disconnected line can be reduced by grounding the overhead line at the place of work. However, in the event of a short circuit or significant load fluctuations on the operating line, a large resistance of the grounding device, the induced voltage at the work site will significantly exceed 25 V, creating a mortal danger to workers. Even grounding the work site does not always reduce the induced voltage to a safe value. The creation of a compensation voltage makes it possible to ensure that the induced voltage does not exceed the maximum permissible value. The essence of the compensation method is the supply of a compensating voltage to the place of work, equal in modulus to the induced one and in antiphase to the latter.

Known methods for compensating for induced voltage at the site of work on a disconnected overhead power line using an autonomous power source with the ability to adjust the magnitude and phase of the compensating voltage (patent RU No. 2541508 C1 dated 03.10.2013, publ. 20.02.2015, bull. No. 5 , patent RU No. 2586 995 C1 dated 06/17/2015 published on 06/10/2016 bulletin No. 16, RU patent No. 2593 277 C1 dated 08/06/2015 published on 08/10/2016 bulletin No. 22, RU patent 2591182 C1 dated May 21, 2015, published on July 10, 2016, bulletin No. 19).

The patent search showed that to compensate for the induced voltage from the overhead line operating in normal operating mode and short circuit mode, many options are proposed based on an autonomous gasoline-electric unit or converter, with a control system that provides automatic control according to the parameters of the induced voltage.

There is a way to compensate for the induced voltage at the work site on a disconnected overhead power line (patent RU No. 2541508 C1 dated 03.10.2013), in which the phase wires of the disconnected line are connected by grounding wires at the work site with the ground loop of the line support at the work site, characterized in that the power of the induced voltage source is preliminarily determined, an autonomous power source is formed with the ability to adjust the magnitude and phase of the compensating voltage, the magnitude of the induced voltage is measured with a voltmeter at the work site, an adjustable power source is connected between the ground loop of the line support and the grounding wires, on which sets a voltage equal in magnitude and in antiphase to the measured induced voltage, and monitors according to the voltmeter readings the residual induced voltage not exceeding 25 V. This method is adopted as an analog useful oh model.

Signs of an analogue that coincide with the essential features of the claimed model are the presence of an autonomous power source with the ability to adjust the magnitude and phase of the compensating voltage, the connection between the ground loop of the line support and the ground wires of an adjustable power source, on which a voltage is set equal in magnitude and in antiphase to the measured induced voltage, and controlled according to the readings of the instruments.

The compensation system, built on the basis of an autonomous power plant, presumably will not provide the required parameters due to the significant inertia of the internal combustion engine control systems. The compensation system based on an electronic converter (inverter) is much faster. In any case, one of the main difficult-to-solve problems is the provision of a compensating voltage in the range from tens of V to hundreds or more. In one of the patents (patent RU No. 2586 995 dated June 17, 2015), it is proposed to use a current-controlled current source (ITUT) for this purpose, the control signal for which can be an induced voltage current flowing through the ground circuit at the work site.

The closest in essence to the proposed model is a method of compensating for the touch voltage at the site of work on an overhead power transmission line taken out for repair (patent RU No. 2586 995 dated June 17, 2015). This method is adopted as a prototype of the claimed model.

Signs of the prototype, coinciding with the essential features of the claimed model, is the use of an autonomous current-controlled current source (ITUT), the control signal for which can be an induced voltage current flowing through the grounding circuit at the work site and grounding of the phase wires of the disconnected line at the work site ...

The disadvantages of the prototype are:

1. In the event of an emergency mode on the influencing line, this method does not provide a decrease in the induced voltage on the line brought out for repair to a safe value. In the case of grounding a disconnected line at the work site and at the ends of the line, the induced voltage at the work site can reach 1000 V or more, which leaves virtually no chance of saving the life of the working personnel. In the case of grounding the disconnected line only at the work site, the induced voltage at the work site reaches 200 V or more with a high resistance of the grounding device.

2. Low reliability of the method due to the absence of a backup power supply unit. In addition, there is no information from the available publications about the practical implementation of ideas from patents and copyright certificates.

Disclosure of the essence of the utility model

The utility model is aimed at improving the reliability of the device to ensure the safety of workers when working on disconnected overhead power lines both in the normal mode of the influencing lines and in the short circuit mode on the influencing lines that create the induced voltage.

The technical result of the proposed utility model is to increase the reliability of the device to reduce the induced voltage at the place of repair work to values less than 25 V, required by the rules of labor protection, due to compensation of the induced voltage by the Device through the grounding resistance at the work site of the overhead power transmission line brought out for repair ...

The technical result is achieved due to the joint parallel operation of the following modules and blocks, made in the same case:

- sinusoidal signal inverter with resistive divider and step-up transformer,

- analog digital converter (ADC),

- a controller that controls modules and blocks UKNN.

Brief Description of Drawings

Figure 1 shows a block diagram of the Induced Voltage Compensation Device (ICDV), which consists of the following blocks and modules, made in the same case:

- an inverter of a sinusoidal signal with a resistive divider and a step-up transformer generates a compensating voltage of high power, ensuring that the level of the compensating voltage is brought to the required values.

- an analog-to-digital converter (ADC) converts the controlled voltage into digital form;

- the controller controls the modules and units of the UKNN, performs the function of monitoring the induced voltage, receiving a signal from the resistive divider of the inverter through the ADC and correcting the level and phase of the compensating voltage by sending an appropriate command to the inverter to continuously monitor the instantaneous value of the level, frequency and phase of the induced voltage, connected to the high-voltage terminal through a resistive divider.

The power supply of the UKNN is carried out from a storage battery and a gasoline-electric unit operating in parallel, which makes it possible to automatically reduce the residual induced voltage to values significantly less than 25 V, both in a steady-state normal mode and in a short circuit on the influencing operating line. Auxiliary devices - remote grounding electrodes, connecting cables.

Implementation of the utility model

The high-voltage terminal of the UKNN is connected to the grounding circuit of the overhead line support or to the point of connection of the phase wires. Another pin of the UKNN is connected to an additional ground ("remote ground") located about 20 m from the overhead line support.

From the high-voltage output, a compensating voltage is supplied, which is in antiphase with the induced voltage, equal in magnitude to it in terms of amplitude, phase and the same frequency.

The induced voltage is fed through the divider to the analog-to-digital converter; the converted signal is transmitted to the controller, in which the magnitude, phase, shape of the induced voltage is estimated and a control signal is supplied to the inverter. The inverter outputs a compensating voltage to the point of connection of the overhead line phases with the grounding device. To ensure reliable synchronization, the residual voltage (the difference between induced and compensating voltage) is maintained at a level of 7-10 V rms, which makes it possible to automatically reduce the residual induced voltage to values significantly less than 25 V both in steady-state and short-term conditions. short circuit on the influencing operating line.

This utility model was made in the form of two prototypes of the UKNN, which were bench tested with a simulator of the induced voltage from the 220 V power network.

Claims (1)

Induced voltage compensation device (UKNN) at the site of work on a disconnected power line, containing a sinusoidal signal inverter with a resistive divider and a step-up transformer, an analog-to-digital converter (ADC) and a controller, while a controller for continuous monitoring of the instantaneous value of the level, frequency and phase of the induced voltage is connected to the high-voltage terminal of the UKNN through a resistive divider, receives a signal from the resistive divider of the inverter through the ADC and adjusts the level and phase of the compensating voltage by sending the appropriate command to the inverter, the high-voltage terminal of the UKNN is configured to connect to the point where the phases of the overhead line are connected to the grounding device, and the other terminal of the UKNN is adapted to be connected to an additional grounding "remote ground", the power supply of the UKNN is configured to receive power from a storage battery and / or a gasoline-electric unit.

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