SU884030A1

SU884030A1 - Method of automatic compensation of capacitive leakage current to ground in three-phase electric network

Info

Publication number: SU884030A1
Application number: SU802895361A
Authority: SU
Inventors: Владимир Сергеевич Прудников
Priority date: 1980-03-19
Filing date: 1980-03-19
Publication date: 1981-11-23

Description

Изобретение относится к способа^ автоматической компенсации емкостных токов утечки и предназначен, в основном, для повышения точности настройки компенсирующих дросселей, обеспечивающей снижение емкостных токов утечки в электрических сетях с изолированной нейтралью трансформатора.The invention relates to a method for automatically compensating for capacitive leakage currents and is intended mainly to increase the accuracy of adjustment of compensating chokes, which reduces capacitive leakage currents in electric networks with an isolated transformer neutral.

Известны способы автокомпенсации, заключающиеся в измерении емкости сетти с помощью тока оперативного источ- ¹ника и преобразовании сигнала, пропорционального измеренной емкости в ток подмагничивания компенсирующего дросселя, осуществляющего настройку последнего в резонанс с емкостью сети Ql^. .' • Недостатком указанного способа автокомпенсации является невозможность учета состояния компенсирующего дросселя: напряжения на нем, индукции в его магнитопроводе. Это приводит к то-.‘ му, что ток управления компенсирующего дросселя не зависит от его парамет.ров и от величины сопротивления и ви2 да утечки. Однако требуемый ток управления, необходимый для резонансной настройки компенсирующего дросселя в зависимости от вида утечки (однофазная, двухфазная и т.д.) , колеблется в широких пределах, так как величина напряжения на компенсирующем дросселе может при этом изменяться от 0 до фазного напряжения сети, в связи с чем точность настройки цепи компенсации по указанному способу в широком диапазоне изменения активных сопротивлений утечки недостаточно высока.Known methods of self-compensation, consisting in measuring the capacitance Setty via current sources operational ¹ nick and converting a signal proportional to the measured capacitance at a bias current of the compensating throttle performing the last adjustment to resonance with capacitance Ql ^ network. . ' • The disadvantage of this method of auto compensation is the inability to take into account the state of the compensating inductor: voltage on it, induction in its magnetic circuit. This leads to that. ' I believe that the control current of the compensating inductor is independent of its parameters and the value of resistance and type of leakage. However, the required control current required for the resonant adjustment of the compensating inductor depending on the type of leakage (single-phase, two-phase, etc.) varies widely, since the voltage across the compensating inductor can vary from 0 to the phase voltage of the network, in this connection, the accuracy of adjustment of the compensation circuit according to the specified method in a wide range of changes in the active resistance of the leak is not high enough.

Известны способы автокомпенсации, в которых системой автоматического регулирования, замкнутой на вспомогательный дроссель насыщения, включённый через систему фильтров между фазами сети и землей, указанный вспомогательный дроссель настраивается в резонанс с емкостью сети на оперативной частоте током, который вводится в обмотку управления компенсирующего дросселя, настраивая последний в ре зонанс с емкостью сети на рабочей частоте сети £2j.Known auto-compensation methods are those in which an automatic control system closed to an auxiliary saturation inductor connected through a filter system between the mains and ground phases, the auxiliary inductor is tuned in resonance with the network capacity at the operating frequency by the current that is introduced into the control winding of the compensating inductor, adjusting the latter resonance with the network capacity at the operating frequency of the network £ 2j.

Однако согласно этому способу замкнутой системой автоматического регулирования не охватывается компенсирующий дроссель, не контролируется его состояние. Неучет напряжения на компенсирующем дросселе и индукции в его магнитопроводе приводит к существенным погрешностям при настройте компенсирующей цепи при различных видах и величинах сопротивления утечки .However, according to this method, a compensating throttle is not covered by a closed system of automatic control, its condition is not controlled. The neglect of the voltage at the compensating inductor and the induction in its magnetic circuit leads to significant errors when adjusting the compensating circuit for various types and values of leakage resistance.

Наиболее близким по технической сущности к изобретению является способ автокомпенсации, который заключа· ется в измерении емкости сети и эквивалентной индуктивности компенсирующего дросселя с помощью наложенного на рабочую сеть и обмотки указанного дросселя тока высокой частоты и настройке компенсирующей цепи в резонанс с емкостью сети на рабочей частоте, замкнутой на компенсирующий дроссель системой автоматического регулирования, отрабатывающей сигнал рассогласования изменением индуктивности компенсирующей цепи W·The closest in technical essence to the invention is a method of auto-compensation, which consists in measuring the network capacity and the equivalent inductance of the compensating inductor using a high-frequency current inductor and winding the specified high-current inductor and adjusting the compensation circuit in resonance with the network capacity at the operating frequency, automatic control system closed to the compensating inductor, which processes the mismatch signal by changing the inductance of the compensating circuit W

Для настройки компенсирующей цепи ток оперативного источника ^! накладывают на емкость сети и на рабочие и на измерительные обмотки компенсирующего дросселя. При этом преобладание индуктивного или емкостного характера оперативного тока определяет работу датчика настройки - фазочувствительного детектора. Наложение тока оперативного источника и на рабочие, и на измерительные обмотки приводит к тому, что ток управления' фазочувствительного детектора определяется не только емкостью сети и индуктивностью измерительной обмотки компенсирующего дросселя, но и индуктивностью рабочих его обмоток. Кроме того, электрическая связь между измерительными и рабочими обмотками дросселя обуславливает необходимость включения в цепь измерительных обмоток дополнительного дросселя с воздушным зазором и фильтра присоединения их к земле для исключения влияния напряжения смещения нейтрали промышленной частоты на работу системы автоматического регулирования и уменьшения влияния изменения индуктивности рабочих обмоток.на индуктивность измерительных обмоток. Однако такое техническое решение наряду с усложнением устройств компенсации не позво25To set up the compensating circuit, live source current ^! impose on the capacity of the network and on the working and measuring windings of a compensating inductor. In this case, the predominance of the inductive or capacitive nature of the operational current determines the operation of the tuning sensor - a phase-sensitive detector. The superimposition of the operational source current on both the working and measuring windings leads to the fact that the control current of the phase-sensitive detector is determined not only by the network capacity and the inductance of the measuring winding of the compensating inductor, but also by the inductance of its working windings. In addition, the electrical connection between the measuring and working windings of the inductor necessitates the inclusion of an additional inductor with an air gap and a filter connecting them to the ground in the circuit of the measuring windings to eliminate the influence of the neutral bias voltage of the industrial frequency on the operation of the automatic control system and reduce the influence of changes in the inductance of the working windings. on the inductance of the measuring windings. However, such a technical solution along with the complication of compensation devices is not possible25

884030 4 ляет получить стабильные характеристики настройки цепи компенсации в широком диапазоне изменения емкости сети. Это вызвано тем, что параметры дросселей, особенно с регулируемым воздушным зазором, имеют, как правило, значительный разброс параметров, которые изменяются как при изготовлении (штамповка, термообработка магнитопроводов ), так и в процессе эксплуатации (колебание напряжения в сети, старение, механические воздействия). Если изменения параметров при изготовлении могут быть учтены индивидуальной настройкой устройств компенсаций, то изменения параметров в процессе эксплуатации учесть невозможно. Этот недостаток.особенно проявляется при растройке цепи компенсации по указанному способу, так как условием настройки в резонанс с емкостью сети на промышленной частоте Ш индуктивности Ьдр рабочих обмоток компенсирующего дросселя является нйстройка индуктивности измерительных обмоток в резонанс с емкостью сети на частоте оператив( Lap ^ο~λ ного источника 1 I . В ре\^LM% ¹ зультате этого даже небольшая расстройка индуктивности в цепи измерительных обмоток приводит к существенным погрешностям в настройке компенсирующего дросселя, что особенно проявляется при максимальных значениях емкости сети.884030 4 It is possible to obtain stable compensation circuit tuning characteristics over a wide range of network capacitance changes. This is because the parameters of the chokes, especially with an adjustable air gap, usually have a significant variation in parameters that change both during manufacturing (stamping, heat treatment of magnetic cores) and during operation (voltage fluctuation in the network, aging, mechanical stresses ) If changes in parameters during manufacture can be taken into account by individual adjustment of compensation devices, then changes in parameters during operation cannot be taken into account. This drawback is especially apparent when the compensation circuit is tuned according to the indicated method, since the condition for tuning in resonance with the network capacitance at the industrial frequency Ш of the inductance Ldr of the working windings of the compensating inductor is to adjust the inductance of the measuring windings in resonance with the network capacitance at the operating frequency (Lap ^ ο ~ λ of the source 1 I. In re \ ^L M% ^{1, as a} result of this, even a small detuning of the inductance in the circuit of the measuring windings leads to significant errors in the adjustment of the compensating inductor, which is especially but appears at maximum network capacities.

Цель изобретения - повышение точности компенсации в широком диапазоне изменения емкости сети.The purpose of the invention is to increase the accuracy of compensation in a wide range of changes in network capacity.

Поставленная цель достигается тем, что в способе автокомпенсации, заключающемся в измерении емкости сети и эквивалентной индуктивности компенсирующего дросселя с помощью наложенного на рабочую сеть и обмотки указанного дросселя тока высокой частоты и настройки компенсирующей цепи в резонанс с емкостью сети на рабочей частоте, замкнутой на компенсирующий дроссель системой автоматического регулирования, отрабатывающей сигнал рассогласования изменением индуктивности компенсирующей цепи, на рабочую сеть накладывают постоянный оперативный ток, измеряют его величину, сравнивают -с величиной тока высокой частоты, наложенного на рабочую сеть, а их разность с величиной тока высокой частоты в цепи измерительных обмоток компенсирующего дросселя и полу5 1 ченную разность токов преобразуют в сигнал рассогласования.This goal is achieved by the fact that in the method of auto-compensation, which consists in measuring the network capacity and the equivalent inductance of the compensating inductor using the high-frequency current superimposed on the mains and winding the said inductor and setting the compensation circuit in resonance with the network capacitance at the operating frequency closed to the compensating inductor a system of automatic control, working out the error signal by changing the inductance of the compensating circuit, a permanent opera is imposed on the working network ivny current, its magnitude is measured, the value is compared -with high frequency current superimposed on a working network, and their difference value with high-frequency current in the circuit measuring windings compensating choke and polu5 1 chennuyu current difference is converted into the error signal.

На чертеже представлена принципиальная блок-схема соединений функциональных узлов для реализации предложенного способа автокомпенсации емкостных токов утечки.The drawing shows a schematic block diagram of the connections of functional units for implementing the proposed method of auto-compensation of capacitive leakage currents.

Источник высокой частоты 1 с помощью присоединительного емкостного фильтра 2, измерительного блока 3 и трансформатора 4 подключен к фазам сети с активными 5 и емкостными 6 проводимостями изоляции относительно земли. С помощью трансформатора 7 и датчика 8 указанный источник 1 присоединен к измерительным обмоткам 9 и 10 компенсирующего дросселя с рабочими обмотками 11, 12 и 13, 14, которые через измерительный блок 15 и индуктивный присоединительный фильтр 16 подключены к фазам сети, а через разделительный конденсатор 17 присоединены к земле, управляющие обмотки 18 и 19 указанного компенсирующего дросселя подключены к выходу релейного эле-25 мента 20, вход которого присоединен к выходу блока сравнения токов 21. Вход блока 21 сравнения токов подключен к выходу датчика 8, который измеряет ток, пропорциональный индуктивности измерительных обмоток 9, 10 и к выходу блока сравнения токов 22, сигнал с которого является функцией емкости сети 6. Последнее обусловлено тем, что ’в блоке 22 происходит сравнение тока высокой частоты, снимаемо10The high-frequency source 1 is connected to the phases of the network with active 5 and capacitive 6 conductivities of insulation relative to earth using a connecting capacitive filter 2, a measuring unit 3, and a transformer 4. Using a transformer 7 and a sensor 8, the specified source 1 is connected to the measuring windings 9 and 10 of the compensating inductor with working windings 11, 12 and 13, 14, which are connected to the mains phases through the measuring unit 15 and the inductive connecting filter 16, and through the isolation capacitor 17 connected to the ground, the control windings 18 and 19 of the compensating inductor are connected to the output of the relay element 25 of 20, the input of which is connected to the output of the current comparison unit 21. The input of the current comparison unit 21 is connected to the output of the sensor 8, otorrhea measures the current proportional to the inductance measuring coil 9, and 10 to the output unit 22 current comparison signal which is a function of a capacitance network 6. The latter is due to the fact that 'in block 22 compares the high-frequency current, snimaemo10

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884030 4 уменьшается.· Вследствие· этого, ток в измерительных обмотках 9 и 10 дросселя увеличивается до тех пор, пока не достигнет тока, снимаемого с блока 22, пропорционального измеряемой емкости сети 6. Сигнал рассогласования на выхода блока 21 в этом случае становится равным нулю и релейный элемент 20 разрывает цепь тока в обмотках управления 18 и 19. В результате индуктивность компенсирующего дросселя увеличивается, а, следовательно, ток в измерительных обмотках 9 и 10 уменьшается. При этом на выходе блока 21 сравнения опять появляется сигнал рассогласования, приводящий цепь' постоянного тока в обмотках управления 18 и 19 в состояние проводимости. Цикл повторяется. Таким образом, условием резонансной настройки цепи компенсации, состоящей из рабочих обмоток 11-14, дросселя, индуктивного присоединительного фильтра 16 и разделительного конденсатора 17, является равенство тока, пропорционального сигналу, являющегося функцией емкости сети 6,’и тока, пропорционального индуктивности измерительных обмоток 9 и 10.884030 4 decreases. · As a result of this, the current in the measuring windings 9 and 10 of the inductor increases until it reaches the current taken from block 22, which is proportional to the measured capacitance of the network 6. The error signal at the output of block 21 in this case becomes equal to zero and the relay element 20 breaks the current circuit in the control windings 18 and 19. As a result, the inductance of the compensating inductor increases, and therefore the current in the measuring windings 9 and 10 decreases. At the same time, at the output of the comparison unit 21, a mismatch signal appears again, bringing the DC circuit 'in the control windings 18 and 19 into a conduction state. The cycle repeats. Thus, the condition for the resonant adjustment of the compensation circuit, consisting of the working windings 11-14, the inductor, the inductive connecting filter 16 and the isolation capacitor 17, is the equality of the current proportional to the signal, which is a function of the capacitance of the network 6, 'and the current proportional to the inductance of the measuring windings 9 and 10.

Предложенное техническое решение позволяет значительно упростить устройства, реализующие предложенный способ автокомпенсации, так как в них не требуются специальные функциональные узлы для устранения влияния напряжения смещения нейтрали промышленной частоты на работу системы автоматичесго с измерительного блока 3, который пропорционален активной 5 и емкостной 6 проводимостям изоляции сети, и постоянного тока, снимаемого с измерительного блока 15, который пропорционален только активной 5 проводимости изоляции сети. Постоянный оперативный источник 23 для измерения активного сопротивления 5 изоляции подключен параллельно разделительному конденсатору 17. Сигнал рассогласования, появляющийся на выходе блока 21 сравнения с помощью релейного элемента 20, управляет током подмагничивания компен^-. сирующего дросселя в его обмотках управления 18 и 19. При появлении сигнала рассогласования,' например, из-за увеличения емкости сети 6, релейный элемент 20 .замыкает цепь постоянного тока в обмотках управления 18 и 19j в результате чего обеспечивается подмагничивание магнитопровода дросселя и индуктивность рабочих обмоток 11—14 кого регулирования и уменьшение влияния изменения индуктивности рабочих обмоток на параметры измерительных обмоток. При •э'Гом измерение емкости сети 6 осуществляется достаточно точно в широком диапазоне ее изменения и характеристика сигнала, являющегося .функцией измеряемой емкости, не зависит ни от активных проводимостей 5 изоляции сети, ни от колебаний напряжения в сети, ни от вида утечки (однофазная, двухфазная и др.) > которая одинаково влияет как на цепь измерения тока высокой частоты в блоке 3, так и постоянного тока в блоке 15, а различные приращения в этих цепях после блока 22 сравнения токов взаимно компенсируются. В то же время цепь измерения индуктивности учитывает состояние дросселя: напряжение на дросселе, индукцию в его магнитопроводе. Это обусловлено тем, что требуемый ток управления для изменения индуктивности ра бочих обмоток зависит от вида и вели-^!чины активной утечки в сети, а,.следовательно, и от напряжения на дросселе, в силу чего изменение индуктивности измерительных обмоток при раз- ₅личных видах утечки учитывается и автоматически вводится в систему отработки рассогласования.The proposed technical solution can significantly simplify devices that implement the proposed method of auto-compensation, since they do not require special functional units to eliminate the influence of the neutral bias voltage of the industrial frequency on the operation of the automatic system from the measuring unit 3, which is proportional to the active 5 and 6 capacitive conductivities of the network insulation, and direct current taken from the measuring unit 15, which is proportional only to the active 5 conductivity of the insulation network. A constant operational source 23 for measuring the insulation resistance 5 is connected in parallel with the isolation capacitor 17. The error signal appearing at the output of the comparison unit 21 using the relay element 20 controls the bias current of the compen ^- sator. a throttling inductor in its control windings 18 and 19. When a mismatch signal appears, for example, due to an increase in the capacity of the network 6, the relay element 20. closes the DC circuit in the control windings 18 and 19j, as a result of which the magnetization of the inductor magnetic core and the inductance of the workers are ensured windings of 11-14 regulation and reducing the influence of changes in the inductance of the working windings on the parameters of the measuring windings. At • e'Gom, the measurement of the capacitance of the network 6 is carried out quite accurately in a wide range of its variation and the characteristic of the signal, which is a function of the measured capacitance, does not depend on the active conductivities 5 of the insulation of the network, nor on the voltage fluctuations in the network, nor on the type of leakage (single-phase , two-phase, etc.)> which equally affects both the high frequency current measuring circuit in block 3 and the direct current in block 15, and various increments in these circuits after the current comparison block 22 are mutually compensated. At the same time, the inductance measurement circuit takes into account the state of the inductor: voltage on the inductor, induction in its magnetic circuit. This is due to the fact that the required control current for changing the inductance of the working windings depends on the type and magnitude ^! ranks of active leaks in the network and, .sledovatelno, and the voltage across the inductor, whereby the change in the measuring coil inductance at ₅ different kinds of leaks of personal counted and automatically entered into the system working off a mismatch.

В связи с тем, .что на практике устройства автокомпенсации емкостных то- щ ков утечки применяются совместно с устройством контроля сопротивления изоляции и защитного отключения (реле утечки), в которых в качестве оперативного источника используется по- _ί5стоянный ток, для упрощения устройства автокомпенсации, реализующих предложенный способ, в качестве источника постоянного оперативного тока возможно использование источника постоянно- ₂₀Го тока устройств контроля сопротивления изоляции. Таким образом, предложенный способ автокомпенсации емкостных токов утечки свободен от перечисленных недостатков известных спосо- ₂₅бов и позволяет упростить и повысить эффективность компенсации емкостной составляющей токов утечки в сетях с изолированной нейтралью трансформатора. ₃₀ In connection with the fact that, in practice, autocompensation devices for capacitive leakage currents are used in conjunction with a device for monitoring insulation resistance and protective shutdowns (leakage relays), in which a _constant current is used as an operational source, to simplify the autocompensation device, implements the proposed method, as a source of constant operational current it is possible to use a source of constant- ₂₀ Go current devices for monitoring insulation resistance. Thus, the proposed method autocompensation capacitive leakage currents is free from the above drawbacks of known sposo- CWA ₂₅ and allows to simplify and increase efficiency of the capacitive component compensation of leakage currents in networks with isolated neutral transformer. _thirty

Claims

This invention relates to a method for automatically compensating for capacitive leakage currents and is mainly intended to improve the tuning accuracy of compensating chokes, which ensures the reduction of capacitive leakage currents in electrical networks with an insulated transformer neutral. Autocompensation methods are known which consist in measuring the network capacity using an operational source current and converting a signal proportional to the measured capacitance to the bias current of the compensating throttle that adjusts after it to resonance with the network capacity LlJ The disadvantage of this autocompensation method is the inability to take into account the state of the compensating drog .sel: voltage on it, induction in its magnetic field. This leads to the fact that the control current of the compensating throttle does not depend on its parameters. durability and type of leakage. However, the required control current required for resonant adjustment of the compensating throttle depending on the type of leakage (single-phase, two-phase, etc., varies widely, since the voltage across the compensating choke can vary from o to phase voltage network, in connection with which the accuracy of adjustment of the compensation circuit in this method in a wide range of variation of leakage resistances is not high enough. There are known methods of autocompensation, in which the automatic adjustment system closed on the auxiliary saturation throttle connected through the filter system between the mains phases and the ground, said auxiliary choke tunes in resonance with the network capacity at the operating frequency with a current that is introduced into the control winding of the compensating throttle by adjusting the latter in resonance with the network capacity at the operating network frequency 2. However, according to this method, the jammed automatic control system does not cover the compensating choke, its state is not monitored. Disregarding the voltage on the compensator 1-th choke and induction in its magnetic core leads to significant errors when setting the compensating circuit for different types and values of leakage resistance. The closest in technical essence to the invention is a method of autocompensation, which consists in measuring the network capacitance and equivalent inductance of a compensating throttle using a high frequency current superimposed on the working network and winding of the specified throttle and resonating with the network capacity at the operating frequency those closed by a compensating choke by an automatic control system, which performs the error signal by changing the inductance of the compensating circuit GZ1, For us Royko compensating circuit operative current source superimposed on network capacity and performance to the measuring coil and the compensating throttle. At the same time, the predominance of the inductive or capacitive nature of the operating current determines the operation of the tuning sensor, the phase-sensitive detector. The imposition of the operational source current on both the working and measuring windings causes the control current of the phase-sensitive detector to be determined not only by the network capacity and inductance of the measuring winding of the compensating throttle, but also by the inductance of its working windings. In addition, the electrical connection between the measuring and working windings of the throttles necessitates the inclusion in the circuit of the measuring windings of an additional throttle with an air gap and a filter connecting them to the ground to eliminate the effect of the bias voltage of the industrial frequency neutral system on the automatic control system and reduce x the effect of changing the inductance of the working windings on the inductance of the measuring windings. However, such a terrible decision, along with the complication of compensation devices, does not allow one to obtain stable tuning characteristics of the compensation circuit in a wide range of changes in the capacitance of the network. This is due to the fact that the parameters of chokes, especially with an adjustable air gap, have, as a rule, a considerable variation in the parameters, which change both during manufacture (stamping, heat treatment of the magnetic cores) and during operation (voltage fluctuations in the network, aging, mechanical stress). If changes in the parameters during manufacturing can be taken into account by individual adjustment of compensation devices, then changes in parameters during operation cannot be taken into account. This disadvantage is particularly manifested when the compensation circuit is configured in this way, since the condition for tuning into resonance with the network capacitance at the industrial frequency tl) of the LAO inductance of the working windings of the compensating throttle is tuning the inductance of the LUT, measuring windings in resonance with the network capacitance at the frequency About operative (1 source 1 fs-rs-I H-ig 1 as a result of this) Even a small detuning of inductance in the circuit of the measuring windings leads to significant errors in the setting of the compensating throttle, which is The aim of the invention is to improve the accuracy of compensation in a wide range of changes in network capacity. The goal is achieved by the method of autocompensation, which measures the network capacity and the equivalent inductance of compensating drossels using the superimposed working network. and the windings of the specified russel of high frequency current and natrojky of a compensating circuit in-Resoance with a network capacity at the operating frequency closed to a compensating Rossel system of automatic By matching the matching signal by changing the inductance of the compensating circuit, a constant operating current is imposed on the operating network, its value is measured, compared to the high frequency current superimposed on the working network, their difference with the high frequency current in the measuring circuit of the compensating throttle. and a half-valued current difference is converted to a mismatch signal. The drawing shows a schematic block diagram of the connections of functional units for the implementation of the proposed method of autocompensating capacitive leakage currents. The high-frequency source 1 is connected to the mains phases with active 5 and capacitive 6 conductance of the insulation relative to the earth by means of a connecting capacitive filter 2, measuring unit 3 and transformer 4. Using a transformer 7 and sensor 8, the specified source 1 is connected to measuring windings 9 and 10 of compensating throttle with working windings 11, 12 and 13, 14, which through measuring unit 15 and inductive connecting filter 16 are connected to the mains phases, and the divider capacitor 17 is connected to earth, the control windings 18 and 19 of the indicated compensating throttle are connected to the output of the relay element 20, the input of which is connected to the output of the current comparison unit 21. The input of the current comparison unit 21 is connected to the output of the sensor 8, to It measures the current proportional to the inductance of the measuring windings 9, 10 and to the output of the current comparison unit 22, the force from which is a function of the network capacitance 6. The latter is due to the comparison of the high frequency current taken from the measuring unit 3 in unit 22 which is proportional to the active 5 and capacitive 6 conductance of the insulation of the network, and the DC current taken from the measuring unit 15, which is proportional only to the active 5 conductance of the insulation of the network. A constant operational source 23 for measuring the active resistance 5 of the insulation is connected in parallel to the separation capacitor 17. The error signal that appears at the output of the comparator unit 21 by means of the relay element 20 controls the bias current of the compensating chokes in its control windings 18 and 19 When a misalignment signal appears, for example, due to an increase in the capacity of the network 6, the relay element 20 closes the DC circuit in the control windings 18 and 19j, resulting in a magnetic bias the throttle plug-in and the inductance of the working windings 11-14 30i decrease. - As a result, the current in the measuring windings 9 and 10 of the choke is increased until it reaches the current taken from unit 22 proportional to the measured capacity of the network 6. The error signal in this case, the output of block 21 becomes equal to zero and the relay element 20 breaks the current circuit in control windings 18 and 19. As a result, the inductance of the compensating throttle increases, and, consequently, the current in measuring windings 9 and 10 decreases. In this case, at the output of the comparator unit 21, an error signal appears, which causes the direct current circuit in the control windings 18 and 19 to be in the conduction state. The cycle is repeated. Thus, the condition for resonant adjustment of the compensation circuit consisting of operating windings 11-14, chokes, inductive connecting filter 16 and separation capacitor 17 is the equality of the current proportional to the signal, which is a function of the capacitance of the network 6, and the current proportional to the inductance of the measuring windings 9 and 10. The proposed technical solution allows to significantly simplify the devices that implement the proposed method of autocompensation, since they do not require special functional units for devices the influence of the bias voltage of the industrial frequency on the operation of the automatic control system and the reduction of the effect of changes in the inductance of the working windings on the parameters of the measuring windings. With this, the measurement of the capacitance of the network 6 is carried out fairly accurately in a wide range of its change and the signal characteristic, which is a function of the measured capacitance, does not depend on the active conductance 5 of the network insulation, nor on the voltage fluctuations in the network, nor on the type of leakage (single phase, two phase, etc.) which equally affects both the high frequency current measurement circuit in block 3 and the direct current in block 15, and the various increments in these circuits after current comparison block 22 are mutually compensated. At that time, the inductance measurement circuit studies the state of the drossel: the voltage across the inductor, the induction in its magnetic circuit. This is because the required control current for changing the inductance of the working windings depends on the type and magnitude of the active leakage in the network, and, consequently, on the voltage on the choke, whereby the change in inductance of the measuring windings for various types of leakage is taken into account and automatically entered into the system of eliminating mismatch. Due to the fact that, in practice, capacitive leakage current compensating devices are used in conjunction with an insulation resistance and protective disconnect monitoring device (leakage relay): in which a direct current is used as an operational source, to simplify the automatic compensation device , implementing the proposed method, as a source of direct operating current, it is possible to use a source of direct current of the devices for monitoring the insulation resistance. Thus, the proposed method of autocompensating capacitive leakage currents is free from the listed disadvantages of the known methods and allows to simplify and increase the efficiency of compensation of the capacitive component of leakage currents in networks with an isolated transformer neutral. A method for autocompensating capacitive leakage current to earth in a three-phase electrical network, consisting in measuring the network capacity and equivalent inductance of a compensating throttle using a specified high-frequency current thrust on the working network and winding and setting the compensating circuit to resonate with the network capacity at the operating frequency , closed by a compensating choke by an automatic control system, regulating, processing the error signal by changing the inductance of the compensating dep and, in order to improve the accuracy of compensation in a wide range of network capacity, a constant operational current is applied to the working network, its value is measured, compared with the high frequency current superimposed on the working network, and their difference with the high-frequency current in the measuring winding circuit of the compensating throttle and the resulting difference in current is converted into an error signal. Sources of information taken into account during the examination 1. USSR author's certificate No. 213171, cl. H Q2 H 1/02, 1964.

2. USSR Author's Certificate No. 235162, cl. H02 H 9/02, 1965.

3. USSR author's certificate number 390620, cl. H 02 H 3/16, 1971.