RU71042U1 - ADAPTIVE ARC PROTECTION DEVICE FOR HOUSING ELECTRICAL EQUIPMENT - Google Patents

Abstract

The device is designed to protect enclosed switchgear enclosures from short circuits, accompanied by an electric arc. The essence of the device is to control the signal level proportional to the luminous flux generated by the electric arc of a short circuit by the measuring body using an optical-electric sensor (photosensor) connected to the measuring part of the device by an electric communication line (ELS). A distinctive feature of the device is the monitoring of the state of the photosensor, ELS, input converter both in normal mode and during short-circuit, as well as the introduction of protection for a time sufficient to eliminate internal damage. This allows you to increase reliability and performance and to simplify the device with its high noise immunity.

Description

The inventive device (utility model) relates to the field of electrical engineering and is intended for the relay protection of electrical equipment of housing design - complete switchgears of indoor (switchgear) and outdoor (KRUN) installations from short circuits (short circuit), accompanied by an open electric arc inside the switchgear compartments.

Known devices for protecting switchgear enclosures from an electric arc KZ, containing working and brake photosensors, a comparison circuit, a threshold element (US Pat. Germany No. 1126011, French Patent No. 2087348, AS USSR No. 851544, No. 1415320, No. 1111224 , No. 997175, No. 1545287, No. 1453518, RF Patent 2162271).

The closest in technical essence (prototype) is a device for protecting switchgear from arc short circuits according to RF Patent 2162271, containing working and brake photosensors, first and second control cables, first and second voltage sources, frequency-dependent element, first threshold element, integrator , second threshold element.

This device provides control of the illumination of the working and brake photosensors. The operation of the device is achieved only when the working signal exceeds the brake signal. The presence in the device of a frequency-dependent element, which forms, together with the working photosensor, control cable, a frequency filter, the transmission coefficient of which is determined by the state of the working photosensor, allows you to effectively tune out the electromagnetic interference induced in the control cable and get a fairly high speed.

However, despite the positive qualities noted above, this technical solution has the following disadvantages: the lack of monitoring of the state of the photosensor, control cables and measuring part, which certainly reduces the reliability of protection, and the presence of a brake channel

designed to increase the detuning from light and electromagnetic interference, complicates both the protection device itself and its installation and commissioning at the substation (the presence of an additional control cable laid in the protected high-voltage switchgear compartments for connecting the brake sensor).

The purpose of the utility model is to increase reliability, speed and simplification.

This goal is achieved by the fact that in the device of adaptive arc protection of electrical equipment of a housing design containing a photosensor, the first output of which is connected in series by the first wire of the two-wire control cable to the first output of the AC voltage source, the first and second threshold elements, the first output organ, the second output of the photosensor are connected by the second a wire of a two-wire control cable with the first input of the input converter, the second input of which is connected to the second terminal of the ballast unit, and its first output is connected to the second output of the voltage source, the output of the input converter is connected to the input of the signal selection unit, the first output of which is connected to the input of the first threshold element, and its second output is connected to the input of the second threshold element, the output of which is connected to the input of the second the delay element to return, and the output of the latter is connected to the second input of the logical element And and the input of the second output organ, the output of the first threshold organ is connected to the input of the first delay element and return, whose output is connected to the first input of the AND gate and its output connected to the input of the first output organ, organ trigger output connected to an input element limits the duration and the yield of the latter is connected to the third input of NAND gate I.

The essence of the device is illustrated by drawings in figure 1 and figure 2. Figure 1 shows a diagram of a device that consists of a photosensor (photodiode) (PD) 1, two-wire control cable (KK) 2, consisting of the first and second wires, voltage source (IN) 3, ballast unit (BB) 4, input converter (VP) 5, signal selection block (BSS) 6, first and second threshold elements (PE1 and PE2) 7 and 8, respectively, of the first and second

return delay elements (EZV1 and EZV2) 9 and 10, logical element 11, first and second output organs (VO1 and VO2) 12 and 13, launching element (ON) 14, duration limitation element (EDI) 15.

Figure 2 shows the timing diagrams explaining the operation of the device in normal mode (figure 2, a) and in emergency mode with a short circuit, accompanied by the appearance of an electric arc in the installation area of the photosensor (figure 2, b).

The photosensor 1 is installed in the high-voltage compartments of the switchgear cells. The control cable 2 provides the functions of an electric communication line and must be twisted with a step of 2-3 cm, and can also be placed on the screen, which significantly reduces the influence of electromagnetic interference arising from the flow of currents from several hundred amperes to tens of kA in alternating circuits current during short-circuit, as well as in operational direct current circuits, for example, when switching switches or shorting the battery pole to ground.

Due to the fact that these measures do not completely eliminate the influence of electromagnetic interference on the operation of the device, it provides a filter element consisting of a photosensor 1, a control cable 2, a ballast unit 4 and an input converter 5. An example of the implementation of a filter element is the switching circuit operational amplifier with multi-loop feedback (Temkina R.V. Measuring bodies of relay protection on integrated circuits. - M.: Energoatomizdat, 1985. - 240 p., see S.88, Fig. 4, 9). In this case, the photosensor 1, control cable 2, ballast unit 4 perform the functions of element Y1 in Fig. 4.9, the specified source. The ballast block 4 can be made in the form of a linear or non-linear resistor, as well as a combination of linear resistors connected in parallel, for example, a rectifier diode is connected in the circuit of one of which. This allows you to separately adjust the transmission coefficient of the signal by positive and negative polarity. Voltage source 3 can be implemented as a sinusoidal voltage source or as an alternating voltage source of a given frequency and waveform.

The voltage transfer coefficient of the input transducer 5, to which are connected in series: a photosensor (photodiode) 1, a control cable 2, a ballast unit 4, depends on the state of the photo sensor and on the performance of the ballast unit 4, because its resistance when current flows in the positive and negative directions can be different. With an unlit photosensor, the transmission coefficient of the positive half-wave voltage is minimal, and with an illuminated photosensor it is maximum. The transmission coefficient of the positive half-wave voltage is determined by the illumination of the photosensor and thereby regulates the sensitivity of the protection device. The transmission coefficient of the negative half-wave voltage is mainly determined by the resistance value of the ballast block 4. Various resistance of the ballast block 4 in different directions allow you to adjust the gear ratio of the input Converter 5.

Block selection of signals 6 is intended to highlight the signs of signals characterizing the normal and emergency modes of electrical installations and devices. Signal selection block 6 can represent, for example, half-wave rectifiers emitting positive and negative half-waves of voltage from the output of input converter 5 (see, for example, Distance and current protection devices of the ШДЭ 2801, ШДЭ2802 / А.N. Birg, G.S. Nudelman types, E.K. Fedorov et al. - M.: Energoatomizdat, 1988, 144 p., Pp. 41-45, Figs. 21 and 22, the trigger of blocking distance protection when swinging). Selection block 6 has two outputs to which threshold elements 7 and 8 are connected, respectively, which control signals in emergency mode of the electrical installation, i.e. with short circuit through an electric arc and in normal and emergency mode. BSS 6 can also be implemented as frequency filters, for example, a band-pass filter or a high-pass filter that selects a signal controlled by a threshold element 7 and a low-pass filter that selects a signal controlled by a threshold element 8. Signal selection block 6 can also be implemented as integrator, at the first output of which a positive signal is formed, at the second - a negative signal.

The first threshold element 7 provides control of the proportional illumination signal inside the controlled switchgear compartments, due to the appearance of an electric arc column. The second threshold element 8 provides control of the signal due to the flow of current through the photodiode 1 in the forward direction. The presence of this current characterizes the integrity of the input circuit of the protection device (photosensor 1, control cable 2, ballast unit 4, serviceability of voltage source 3 and input converter 5).

The delay elements for the return of 9 and 10 ensure the stable operation of the protection device with the pulsed nature of the output signals of the threshold elements 7 and 8, by extending their existence for a period of 10 ... 30 ms.

The logical element And 11 generates an input signal for the output organ 12 only if the first threshold element 7 is triggered and the input circuit is operational (when the second threshold element 8 is triggered). The operation of the second output organ 13 with a long absence of the output signal of the delay element to return 10 indicates a malfunction of the input circuit of the protection device. The first output organ has a limited duration of the formation of the output signal, which eliminates the wrong actions in the event of a malfunction of the measuring elements of the proposed protection device. The maximum time of formation of the output signal by the output organ 12 is due to the limit time for eliminating internal short circuits in the switchgear. At the same time, the device has a control channel for another symptom of a short circuit, for example, current or voltage levels (see, for example, V. Nagay. Classification of methods and analysis of information signs for detecting arc short circuits in electrical installations of a cabinet structure. - Izv. Universities Sev. - Caucasus region. Technical sciences. 2001, No. 2. P.50-54 or Nagai V.I. Relay protection of branch substations of electric networks. - Energoatomizdat, 2002. - 312 p.), Consisting of a sequentially connected starting element (ON ) 14 and the constraint element I the duration of the signal (EDI) 15. The output of EDI 15 is connected to the third input of the logic circuit And 11. The lifetime of the output signal of EDI 15 does not exceed the duration

tripping of an external short circuit and time of a selectivity stage, which allows reliable disconnection of external short circuits passing into internal short circuits when the high-voltage circuit breaker is unsuccessfully disconnected. At the same time, it is possible to exclude unnecessary trips with external short-circuit and the presence of powerful electromagnetic interference. The presence of three channels that control the level of light flux (illumination), current (voltage) and the health of the photosensor circuits makes it possible to ensure reliable operation of the device in any modes. The prolonged existence of one of the signs and the absence of the other is perceived by the defense as a malfunction (see, for example, distance and current protection devices of the ШДЭ 2801, ШДЭ2802 / A.N.Birg, G.S. Nudelman, E.K. Fedorov, etc. - M .: Energoatomizdat, 1988, - 144 p.).

In normal mode, the device is in the following state: the photosensor 1 is unlit, the current flows through it only when the voltage of the source 3 is negative. The input converter 5 converts the voltage, for example, by scaling, filtering, etc. The output voltage of the input Converter 5 is supplied to the input of the signal selection block 6, which is subjected to secondary processing, for example, is divided into half-waves using half-wave rectifiers (positive and negative half-waves) or various harmonic components are distinguished. In the latter case, the main harmonic component and the highest harmonic components are allocated at the first output of the FSN 6, the constant component is allocated at its second output. The signal level at the first output of the BSS 6 is insignificant due to the small transmission coefficient of positive half-waves of voltage by the input converter 5 (the resistance of the photodiode in the reverse direction for the positive voltage of source 3 is high) and therefore insufficient for the first threshold element 7 to operate, the output of which has a logic zero signal . The signal level at the second output, on the contrary, is large, because the photodiode 1 for the negative polarity of the voltage of the source 3 is turned on in the forward direction, which leads to the actuation of the second threshold element PE2 8 and to the appearance of one logic signal at its output. It causes

formation at the output of the delay element for the return of 10 logical signal unit, the duration of which is extended by 10 ... 30 ms. With the arrival of the next impulse, the action of EZV2 10 is extended again by the mentioned time. The triggered state of the return delay element 10 does not allow generating an output signal to the output organ 13, at the output of which there is a logical signal zero. The return delay element 9, the starting element 14, the element, duration limits 15, the logical element And 11, and the first output organ 12 are in an unused state and a logic zero signal is generated at their outputs.

The described state of the device is illustrated by the figure in figure 2, a, the output voltage on which are indicated by the numbers of the corresponding elements. In this figure, the states of the elements correspond to the inclusion of source 3, i.e. zero initial conditions (return delay elements were in the zero state). In a stationary state, at the output of the return delay element 10, there is a high level signal, i.e. logical unit. The signals of the remaining elements correspond to the diagrams in figure 2, a.

With an internal short circuit, accompanied by an electric arc, the illumination in the switchgear cell and the light flux incident on the photosensor 1 are many times increased (Fig. 2, b). As a result of this, the conductivity of the photosensor 1 increases and the signal level of the positive half-waves at the output of the input transducer 5 and BSS 6 (the first output) increases and becomes sufficient to overcome the response level , of the first threshold element 7. At the output of the threshold element 7 and the delay element for return 9, a signal is generated by a logic unit, which is fed to the first input of the logic circuit And 11. At the second input And 11, in the presence of negative half-waves at the second output of the BSS 6, the second the threshold element 8 and the second EZV2 10, which indicates the health of the photosensor 1, two-wire control cable 2, ballast unit 4 and the input Converter 5, a logical unit is also formed. At the outputs of the threshold organ 14 and the element for limiting the duration of the signal 15, a logical unit signal is formed, which

provides the appearance of the enable signal at the third input of the logical element And 11, and at its output also appears the signal logical unit. This ensures the response of the output organ 12, affecting the shutdown of the switchgear and the elimination of the accident. At the output of the second output organ, as well as in the absence of a short circuit, an output signal of logical zero is generated.

In the presence of short-term interference arising in the sensor circuits, the control cable does not work, due to the presence of a complex of filter elements in the input converter 5, the signal selection block 6, and also the absence of the trigger actuation 14. The corresponding choice of the trigger voltage of the first threshold element 7 and time constants output organ 12 can ensure that the device is triggered only at a certain duration of the signal of positive polarity at the output of the FSU 6, which ensures t the noise immunity of the device and the reliability of operation even in the presence of powerful electromagnetic interference in conditions of external short-circuit, when it is possible to trigger the launching organ 14.

When the control cable or one of the elements of the input circuit is broken off at the second output of the signal selection block 6, there are no signals sufficient to trigger the second threshold element 8, which causes it to return to its original state and, as a result, the second delay element to return 10 and, therefore, the second output organ 13 , thus indicating the malfunction of these elements. The operation of the second output organ 13 occurs in the absence of a signal at the output of the second delay element to return 10.

The speed of the protection device is determined by the following factors: the rate of increase in the level of the light flux in the protected compartment, the frequency of the signal from the voltage source 3, the time delays introduced by the input converter 5 and the signal selection block 6 due to the presence of inertial elements in them. A significant reduction in the response time of the device can be achieved by increasing the frequency of the voltage of the voltage source 3, while the inertia of the frequency filters in the input converter 5 and the signal selection block 6 is reduced.

Simplification of the device and increasing its reliability is achieved both by the use of the same type of elements (PE1 and PE2, EZV1 and EZV2, VO1 and VO2), and by introducing into it a device for monitoring the photosensor, connecting wires, AC voltage source, ballast block, input converter, starting organ and an element for limiting the duration of the signal. The presence of these elements in the relationship with each other allows you to timely identify the malfunction of the device, reduce the number of checks and increase the inter-check interval. Adaptation of the device to operating conditions consists in changing the transfer coefficients of the input converter depending on the state of the photosensor, in generating output signals when the input circuits are in good condition and blocking the device when they malfunction.

Currently, the device according to the proposed scheme has been put into operation and field tests have been carried out, confirming its performance and positive qualities.

Claims (1)

Adaptive arc protection device of electrical equipment of a housing design containing a photosensor, the first output of which is connected in series by the first wire of the two-wire control cable to the first output of the AC voltage source, the first and second threshold elements, the first output organ, characterized in that the second output of the photosensor is connected by the second wire of the two-wire control cable with the first input of the input Converter, the second input of which is connected to the second output of the ballast block, and its ne the output terminal is connected to the second terminal of the voltage source, the output of the input converter is connected to the input of the signal selection block, the first output of which is connected to the input of the first threshold element, and its second output is connected to the input of the second threshold element, the output of which is connected to the input of the second return delay element and the output of the latter is connected to the second input of the AND gate and the input of the second output organ, the output of the first threshold organ is connected to the input of the first return delay element, exit which is connected to the first input of the AND gate and its output connected to the input of the first output organ, organ trigger output connected to an input element duration limitations, and the output of the latter is connected to the third input of NAND gate I.