SU790062A1 - Device for protecting high-voltage apparatus from earthing - Google Patents

Description

(54) DEVICE FOR PROTECTING A HIGH-VOLTAGE INSTALLATION FROM LOCKING TO EARTH

one

The invention relates to relay protection devices and can be used in the operation of high-voltage installations for the purpose of diagnosing insulation conditions.

A protection device is known which contains a pulsed power direction element, current and voltage starting elements, voltage and zero-sequence current transformers. The outputs of the voltage transformer and the zero-sequence current transformer are connected to the input of the pulsed power direction body, and the output of the Power direction organ. connected to the input of the logic circuit And to the executive relay.

However, the known current transformers and zero-sequence voltage do not allow to isolate the damaged yJO phase, and the device captures only the moment of the appearance of partial discharges and does not fix their intensity. As a result, the device may trigger if there is a high level of interference in the network.

A device is known which uses a method of isolating partial bits from interference by the polarity of the pulses and by their amplitude. If a

Since the amplitudes of positive and negative pulses differ significantly, then corona discharges are present in the system, and with a slight difference partial t2j discharges.

However, in the known device, the fixation of the fact of the occurrence of partial discharges is carried out by one parameter (voltage pulse, which significantly reduces the noise immunity of the device, and with a significant level of interference, the system turns out to be inoperable.

The closest technical

15 of the essence to the present invention is a device consisting of a pulsed power direction organ, a voltage triggering organ, a pulse counter, current transformers, a zero-sequence voltage filter, high-pass filters, logic circuits, and damaged phase indicators. Outputs of impulse organ of direction

25 through filters that emit pulsed signals, to current transformers of each phase and to a zero voltage sequence filter. One output of the impulse element of the power direction is connected to the pulse counter. and others to indexes of the damaged phase. To ensure a given noise immunity, impulse starting voltage organs are introduced. Such a circuit disables the protection object when the number of pulses of the partial bits exceeds a predetermined value, with the number of partial bits being counted together for all three phases. To ensure a given noise immunity, impulse starting voltage organs with pulse delay 3} are introduced. The disadvantages of the known device are the following: in systems with a large level, it is difficult to isolate the damaged phase, since when voltage pulses appear in one phase, they affect the other phases via a common voltage channel on other phases to maintain constant control over the state of the relay and the meter reading skips the partial bits after the relay triggers, thus losing the last information about the state of the object; It is impossible to maintain constant control over the quality of the insulation of the object. The purpose of the invention is to differentiate the functionality of the device. The goal is achieved in those in the device containing a pulsed power organ-direction, the current and voltage outputs of which are connected via filters and current transformers respectively to the filters, and the external damage of the indicated relay is connected to the first input of the logic element whose second input is connected to the output of the starting organ, the second output is the internal damage of the pulse power direction relay connected to the input of the pulse counter, the output of which is connected to the first input of the alarm relay Ignalization, power direction organ, logical element I, triggering organ, pulse counter, alarm reps are installed in each phase, an impulse power estimator and an intensity recorder are currently introduced in each phase, and the impulse power estimator inputs are connected through filters to current transformers and voltage, its output is connected to the input of the pulse intensity recorder at the current time, the output of the latter is connected to the second input of the alarm relay signaling, and the triggering organ is made in the form of a current organ, which is connected through the filter to the current sensor. The information pulses are formed under the action of two independent parameters of the detected phenomenon of the current growth pulse and the voltage drop pulse in each phase. This design of the device eliminates the roping of information signals that occur after the relay is triggered, and provides continuous monitoring of the state of isolation of the object by changing the intensity of partial discharges in time. FIG. 1 is a block diagram of the proposed device; in fig. 2 zones of internal and external closures. The block diagram consists of transformers l - 1 voltage, transformers 2-2 current1 filters s - 3 pulse starting organs 4 - 4 currents, logic elements 5 -, pulse Organizers b - b power direction G - 3 counters 7 - 7 pulses , recorders 8–8 intensity of pulses of partial bits at each current time phase, relay 9–9 alarms, organs 10–10 estimating values of pulsed power. The outputs of voltage transformers 1 and current 2 of each phase through the corresponding high-pass filter 3 are connected to the inputs of a pulse voltage power authority and to the Input 10 of the pulse power rating of each phase, the outputs of which are connected to the PDD intensity recorder at the moment of time. To provide a given noise immunity to the output of the filters 3 of the upper frequencies of the current channel of each phase, pulsed current trigger elements 4 are connected. The device works as follows. At partial discharges and incomplete breakdowns in the protection zone (Fig. 2) in current transformers 2 and voltage 1, the corresponding phase induces current growth impulses — long and voltage decreases — negative. The pulses allocated by the high-pass filters 3 are passed to the pulsed body 6 of the directivity of the corresponding phase and the body 1C of the pulsed power estimate. The organ b determines the sign of the instantaneous power if the input signal exceeds its own threshold, and sends them to the input of the pulse counter 7 if the signal phase corresponds to internal faults. The pulse counter 7 counts the number of pulses received at its input in a single time. The evaluation authority 10, the magnitude of the pulse power, estimates the average power of the pulses and issues a signal to the recording device 3, which marks the current jjHHHOcTb pulses at the current time. If the intensity of the pulses is such that their average power exceeds a predetermined level, at a certain frequency, an alarm 9 of the corresponding phase is triggered. The level at which the alarm relay is triggered is set in dependence on the operating voltage and the existing standards on the insulation. In case of complete, breakdown of insulation, standard relay protections are triggered, switching off the object.

In case of breakdowns, complete or incomplete, as well as partial discharges in the protection zone, the polarity of the current and voltage pulses is one. name. The impulse body 6 of the power direction, estimating the sign of the power, triggers the external damage signal for the corresponding phase of the logic element 5 I. At that phase, where the input pulses of the elements 5, coming from the organs 4 and 6, coincide in sign and time, an external damage signal is issued. The intensity and frequency of the follow-up of breakdowns and partial discharges depends on the quality of the insulation. According to their value, the state of isolation of the object during its operation is judged. When determining the intensity of incomplete breakdowns and partial discharges, or at a high frequency of their following, it is concluded that the facility is not operated, which prevents accidents.

The advantages of the proposed device are as follows:

The ability of the device to operate in all types of damaged insulation relative to the ground, complete or incomplete breakdowns, intense partial discharges

the unambiguity of the choice of the damaged phase and the damage zone, which is ensured by the separate inclusion of current and voltage sensors in each phase

the possibility of continuous monitoring of the state of isolation of objects, which allows for preventive work to prevent accidents and thereby increase the operational reliability of the equipment.

The technical effect is determined by the reduction in costs caused by accidents and the sudden disconnection of consumers.

Claims (3)

1. USSR author's certificate 274197, cl. H 02 And 7/06, 1974. 2.Certificate of the USSR 0 417747, cl. H 02 H 7/06, 1976. 3. Authors certificate of the USSR. 329864, class H 02 H 7/06, 1975. - ..  . f fl If External ao6ftexiffftja U2 /