RU9099U1 - ADAPTIVE RESERVE DEVICE FOR RADIAL LINES WITH BRANCHES - Google Patents

Abstract

A device for adaptive backup protection of a radial line with branches, containing current and voltage sensors according to the number of phases of the line, a converter of the reactive component of the current, the first threshold element according to the number of phases of the line, an OR logic element, a response delay time element and an output organ connected in series, characterized in that that an additional converter of the active component of the current is connected, connected by inputs to the outputs of the current and voltage sensors, and by the output - with the first input of the brake ala, the output of which is connected to the second input of the subtractor, the first input of which is connected to the output of the converter of the reactive current component, the output of the subtractor is connected to the inputs of the first threshold element and the second threshold element with an inverse output, the outputs of the second threshold elements of each phase are connected to the second, third and fourth inputs logical element And, the fifth input of which is connected to the inverse output of the third threshold organ, the input of the latter is connected to the current filter of each phase, to the outputs of the current and voltage sensors The inputs of the phase comparison body are connected, the output of which is connected to the second input of the brake signal generation circuit.

Description

RADIAL ADAPTIVE RESERVE DEVICE

LINES WITH BRANCHES

The inventive device (utility model) relates to electrical engineering and can be used for backup power radial overhead and cable lines having branches with transformer substations.

Known technical solutions for the backup protection of overhead lines with transformers on the branches described in 1,2,3

So, for example, in 1 a technical solution is proposed, the principle of which is based on the purposeful introduction of distortions of the current shape during short circuiting (short circuit) behind the branch transformer. To do this, a reactor is installed at the branch substation, which is saturated during short circuit, which increases the balance relay at the supply end of the overhead line (OHL). This implementation of protection requires the installation of additional equipment at the branch substation, which complicates the protection scheme and reduces its reliability.

In 2, it is proposed to build on the basis of a reverse sequence current relay, a power direction relay and a direct sequence current relay, an increment relay, and a direct sequence current decay relay. The protection is started from the reverse sequence current relay, and the protection pickup during the transition to a symmetrical short circuit is performed through the current relay chains and the direct sequence power direction relay. The disadvantage of this device is the failure of protection during the short-term existence of interphase faults and the insufficient speed of the reverse sequence current relay. The increment (decay) of the currents of the direct sequence also occurs when the electric motors start up (self-start) and when the line is switched on in the automatic reclosure cycle, which must be taken into account when choosing the settings and this limits its sensitivity.

Н02Н 3/08

sensitivity, an increase in the number of stages of protection is necessary, which leads to a complication of protection. In addition, it is necessary to adjust the protection against the mode of switching on the loaded line. It is also necessary to roughen the protection in the presence of a motor load. Zashdga is made in a two-phase design, which limits its sensitivity in case of a two-phase short circuit on the low voltage side of the transformer, the winding of which is connected in a triangle.

The closest technical solution (prototype) is a device for back-up current protection of a dead-end line with branches from a phase-to-phase short circuit 4, which consists of a linear current-to-voltage converter, a multi-bit ADC, a subtractor, a shift register, a comparison unit, a set point unit, the first, second logic elements OR NOT, the first - fourth elements of time, the first - third logical elements AND, the element MEMORY, clock generator, executive body, timing switch, voltage converter zheniya a voltage amplifier - limiter, a low frequency filter, inverter reactive current component, zshneynogo current-voltage converter.

The advantage of this protection device is increased sensitivity compared to overcurrent protection, responding to full currents. This is achieved by increments of currents or their reactive components. Such a construction allows reducing the operating current to the level of a lower load current of the maximum power transformer. However, the drawback of the described technical solution is the complexity, since communication with the automatic reclosure device is required, the position relay is disconnected from the switch, the contacts of the switch control key, and the need to detune from the turn-on mode of the line in time, the sensitivity is reduced when the powerful motor load on the branches of the line is available.

In addition to the detuning of the module by the modulus of the current of the reactive component (increment), it is necessary to detune in time from the start-up time, which is often unacceptable, since this time can be significant values, exceeding the time of thermal resistance of electrical equipment on the lower voltage side (for example, switchgear switchgear cells).

The purpose of the utility model is to increase sensitivity, simplification.

This is achieved by the fact that in an adaptive backup radial line protection device with branches containing current and voltage sensors, according to the number of phase lines, a reactive current component converter, a first threshold element according to the number of phase phases, an OR logic element, a response delay element and an input the body is connected in series, an additional converter of the active component of the current is connected, connected by inputs to the outputs of the current and voltage sensors, and by the output from the first input of the brake a needle whose output is connected to the second input of the subtractor, the first input of which is connected to the output of the converter of the reactive current component, the output of the subtractor is connected to the inputs of the first threshold element and the second threshold element with an inverse output, the outputs of the second threshold elements of each phase are connected to the second input, the third and the fourth inputs of the AND gate, the first input of which is connected to the inverse output of the third threshold organ, the input of the latter is connected to the output of the current filter nosti, whose input is connected to the outputs of the current sensors for each phase, the outputs of voltage sensors connected to inputs of the phase comparison body whose output is connected to the second input forming the input body.

In FIG. 1 shows a structural diagram of the proposed device.

The device contains sensors and voltages (DN) 1 and current (DT) 2, converters reactive (ORS) 3 and active (PAS) 4 component of the current, the phase comparison (OSF) 5, the body of the formation of the brake signal (OFTS) 6, vygatel (RF ) 7, first (PEO 8 and second (PEG) 9 threshold elements, measuring blocks 10, 11, 12 of each phase, formed by elements 1-9, logical elements OR 13, AND 14, zero-sequence current filter (FTPS) 15, third the threshold element (PEZ) 16, the element of the delay time to work (EBV) 17, the output organ (IN) 18.

The voltage sensors 1 and current 2 carries out the conversion of voltage to voltage and current to voltage, respectively. Converters of the reactive component of current 3 and the active component of current 4 carry out the selection of components according to the expressions:

The phase comparator 5 generates a signal proportional to the phase angle between the current and voltage, which is fed to the input of the brake signal generation circuit 6. Depending on the magnitude of the phase angle, the transmission coefficient of the SFTS circuit 6 is formed. The imager 7 generates an output signal

The threshold level of the threshold element 8 is selected from the minimum possible values to increase the sensitivity of the protection. The level of response of the threshold element 9 is selected from the condition U k / jt where U is the operating voltage of the threshold element 9; L, is the coefficient of proportionality; // Osh-t- the maximum possible current during short-circuit behind the transformer of the highest power.

Elements 1–9 form blocks 10–12, which are installed 1 stitching in each phase.

The threshold element 16 with an inverse output is connected to the zero-sequence current filter 15. The logic element OR 13 combines the outputs of the first threshold elements 8 of the measuring units 10-12. The logic element And 14 implements the shaping of the output signal in the presence of an enable signal of the element And 13 and the absence of blocking signals at the second, third, fourth and fifth inputs. The time delay element for operation 17 ensures the coordination of the operating time of the line protections and the protections installed on the branches. With the help of the output element 18, the line circuit breaker is tripped.

In normal network operation mode, the described device is in the following state. At the output of DN 1, the voltage is b.1shzko to the nominal, and at the output of DT 2 it is in the range from zero to the normal value, which is determined by the level of the line load current. At the output of the converters of the reactive component of the current 3 and the active component of the current 4 there are sigIP / sin and / d / cos.

U ,, (p.I

The channels are determined by the module and the line current argument. The output signal of the phase comparator 5 has a minimum value, which ensures a minimum value of the transmission coefficient of the brake signal generation circuit of the SFTS 6. At the output of the subtractor 7 there is a signal level that is less than the threshold for operation of PE 8 and 11E2 9. At the same time, the outputs of OR gates 13 and And 14, the shutter element 17, the output organ 18 there are logical signals 0. At the output of the FTPS signal is close to zero, and at the output of the PEZ 16 the signal is logical 0.

When a lhsh is turned on in the automatic reclosure cycle, taking into account the motor load, the phase angle between the current and voltage can exceed the maximum value of the angle of the check in the steady state. This leads to a change in the output signal of the phase comparator 5, which causes a change in the braking coefficient in the body of the formation of the brake signal 6. Despite the increase in the signal value of the converter of the reactive component, current 3, the braking on the channel of the converter of the active component of the current 4 also increases, which ultimately does not lead to the triggering of threshold elements 8 and 9.

Let us compare two options for implementing long-distance reservation when implemented with the prototype device and with the proposed solution. Suppose the motor load of the overhead line is 1 meter 50% (), 5) of its total miscibility.

Current operation device - prototype ravei:

fcp npomomma 0-94- / „s.

The operating current of the proposed device should be selected from the condition of the detuning and the increment of currents after the reclosure, and the total current of the overhead line:

3 /

1pp offer . 9ng +0. ) - 7Y (sm (ptt2 +0 1 „rE„) - OD2 / „2,

where kj, ke are the stock and return coefficients; , - angles of loading and starting of electric motors; kT (9) l is the braking coefficient, which depends on the angle between voltage and current; 1 - the total current load of the overhead line in maximum mode.

/ V o / V- o

As a comparison of backup protection options shows, the effectiveness of the proposed solution compared to the prototype device is 143 - 206%, with 5, 5, 3.0 and 1.6.

When short circuit behind the transformer, the reactant 1P) 1x and the active component currents are injected by the phaser 3 and 4, and depending on the load mode, which is superimposed on the emergency mode, the braking signal is generated by elements 5 and 6. The total signal of the extender turns out to be the threshold of the threshold element 8 and less the threshold of the threshold element 9, which provides the output signal is the logical unit of the logic elements OR 13 and AND 14 and the start of the time delay element 17 and after the time delay of the emulsion explosive 17 occur dit forming line disable signal pomoPTs.Yu output member 18.

The response current of the threshold element 8 is determined by the detuning from the start current (self-start) of the electric motors connected to the branch transformers and is determined by the expression:

 k, k „(sm (p„ -kJ, (f)), -, (p)

where fkz - the angle between voltage and current during short circuit behind the transformer; ked is the relative fraction of the power of the motor load in the total power of the overhead line.

In case of interphase short circuit on overhead line, the device operates as well as in short circuit behind the branch transformer, except that the threshold element PEZ 9 is activated, which blocks the action of the protector due to the appearance of a signal at its output.

The current for the start of the threshold element 9 is selected from the condition of the detuning from the short-circuit current 1kzt for the transformer of the greatest capacity, i.e.

where FKZ is the angle between voltage and current during short-circuit behind the transformer.

Thus, the use of adaptive braking of the active component of the current under the influence of the phase comparison organ allows increasing the sensitivity of the backup protection to interphase fault behind branch transformers and operating the device at short-circuit currents significantly lower than the maximum

load currents, start-up currents (self-starting) of electric motors connected to the protected excess.

1. A device for backup protection of the soldering transformer. A.S. USSR 1319144, MKI H02H 7/04. Kuznik Yu.S. Publ. 06/23/87, Bull. Number 23.

2. Device for backup line protection with soldering transformers. A.S. USSR 1737611, MKI H02H 7/28. Kuznik Yu.S. Publ. 10/17/89, Bull. No. 20.

3. Device for current protection against interphase short circuit of a three-phase electrical installation. A.S. USSR 1116488, MKI Н02Н 3/08, Н02Н 7/00. Bogdan A.V., Kletsel M.Ya., Nikitin K.I. - Publ. 09/30/84, Bull. No. 36.

4. A device for back-up current protection of a dead-end line with branches from an interphase short circuit. A.S. USSR 1361668, MKI Н02Н 3/08. Kletsel M.Ya., Kopbaev M.A., Nikitin K.A., Polyakov V.E. - Publ. 11.23.87, Bull. No. 47.

Literature

The applicants Nagay Vladimir Ivanovich Sarah Sergey Vladimirovich

Chizhov Konstantin Vladimirovich Kotlov Mikhail Mikhailovich

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Claims (1)

A device for adaptive backup protection of a radial line with branches, containing current and voltage sensors according to the number of phases of the line, a converter of the reactive component of the current, the first threshold element according to the number of phases of the line, an OR logic element, a response delay time element and an output organ connected in series, characterized in that that an additional converter of the active component of the current is connected, connected by inputs to the outputs of the current and voltage sensors, and by the output - with the first input of the brake ala, the output of which is connected to the second input of the subtractor, the first input of which is connected to the output of the converter of the reactive current component, the output of the subtractor is connected to the inputs of the first threshold element and the second threshold element with an inverse output, the outputs of the second threshold elements of each phase are connected to the second, third and fourth inputs logical element And, the fifth input of which is connected to the inverse output of the third threshold organ, the input of the latter is connected to the current filter of each phase, to the outputs of the current and voltage sensors The inputs of the phase comparison body are connected, the output of which is connected to the second input of the brake signal generation circuit.