CN201813165U - Intelligent control and protection compound switch - Google Patents

Abstract

An intelligent control and protection compound switch includes a singlechip unit, an SCR (Silicon Controlled Rectifier) zero-crossing switching circuit, an anti-parallel one-way SCR and a protection device thereof, a magnetic latching coil driving circuit and a magnetic latching relay thereof, a full wave detection circuit and a communication circuit, wherein the SCR zero-crossing switching circuit, the magnetic latching coil driving circuit, the full wave detection circuit and the communication circuit are connected with the singlechip unit; the anti-parallel one-way SCR and the protection device thereof are connected with the SCR zero-crossing switching circuit, and the magnetic latching relay is connected with the magnetic latching coil driving circuit. The intelligent control and protection compound switch not only solves phenomena, such as breakdown of the SCR, sintering of the magnetic latching relay and the like, but also has functions of under-current and over-current protection, capacitor state diagnosis and fault reminding, which are not configured in the conventional domestic compound switches, moreover, the intelligent compound switch provided by the utility model is low in cost and wide in application prospect.

Description

Intelligent control and protection composite switch

technical field

The utility model relates to a switch actuator used in an electric power system, in particular to an intelligent control and protection composite switch. the

Background technique

Composite switch is a relatively economical new low-voltage reactive power compensation capacitor’s zero-crossing switching device. The so-called zero-crossing switching refers to voltage zero-crossing input and current zero-crossing cut-off. The capacitor is connected to the system at the moment when the voltage is equal, so that there will be no inrush current (that is, a short-duration current); The peak moment of the phase voltage (the phase current corresponding to the phase voltage is zero) is disconnected, so that the zero-crossing cutting of the capacitor current can be realized, thereby realizing the arc-free disconnection of the switch contact. the

Compared with switching elements such as AC contactors, thyristors or solid state relays, the composite switch has greater technical advantages, and its basic working principle is to connect the thyristor switch and the magnetic latching relay in parallel to realize voltage zero-crossing conduction ( That is, the voltage zero-crossing input) and the current zero-crossing cut off, so that the composite switch has the advantages of a thyristor switch at the moment of turning on and off, and has the advantage of no power consumption of a contactor switch during normal turning on. Compared with pure AC contactors or pure thyristor switching devices, the composite switch has significant technical advantages, such as high efficiency, low consumption, environmental protection and energy saving, especially greatly improved performance in terms of inrush current, safety and reliability. The implementation method of the composite switch is: when the voltage crosses zero at the moment of zero-crossing when inputting, the thyristor switch connected in parallel with the magnetic latching relay is triggered, and then the magnetic latching relay is sucked in and turned on after it is stable; When the relay is disconnected, the thyristor switch will be turned on immediately after the voltage crosses zero, so as to avoid the magnetic latching relay disconnecting the voltage to generate an arc. zero cutoff). the

Judging from the current use in the market, most of the composite switches of domestic manufacturers have a high failure rate, unstable work, and many safety hazards. The main problems are the breakdown of the thyristor switch and the sintering of the magnetic latching relay, and many composite switches are failing. Finally, because it is installed in the capacitor cabinet, no one knows it, which greatly affects the compensation effect of the entire compensation device. the

After analyzing the cause of the fault, it is found that because the load is a capacitor, which is different from the resistive load, the protection method for the thyristor switch is different. In addition, whether the thyristor switch is triggered at zero crossing, how to control the shortest thyristor switch conduction Most manufacturers have not found a real solution to this. In addition, in order to improve market competitiveness, many manufacturers use components that do not meet performance indicators in order to reduce production costs, and fail to take necessary software and hardware protection methods. Further affect the quality of composite switch. In addition, due to the low cost and low price of these low-quality composite switches, this greatly disrupts the sales market of composite switches and has a relatively large negative impact on the improvement of composite switch technology. the

Therefore, a new composite switch is needed to effectively eliminate unsafe phenomena such as breakdown of the thyristor switch and sintering of the magnetic latching relay existing in the existing composite switch, and improve the control and protection functions of the composite switch. the

Utility model content

The technical problem to be solved by the utility model is to provide an intelligent control and protection composite switch, the intelligent control and protection composite switch can not only effectively perform zero-crossing switching on capacitors in the power system, but also provide perfect protection functions , which can effectively prevent the thyristor zero-crossing trigger circuit from being unstable, the thyristor from being damaged, and the sintering of the magnetic holding contact, and can provide a reliable fault detection function when the composite switch fails. the

In order to solve the above basic problems, the utility model provides an intelligent control and protection composite switch, which includes a single-chip microcomputer unit, a thyristor zero-crossing switching circuit, an anti-parallel unidirectional thyristor and its A protection device, a magnetic latching coil drive circuit and its magnetic latching relay, a full-wave detection circuit, and a communication circuit, wherein the thyristor zero-crossing switching circuit, the magnetic latching coil drive circuit, the full-wave detection circuit, and the communication circuit are connected In the single-chip microcomputer unit, the anti-parallel one-way thyristor and its protection device are connected to the zero-crossing switching circuit of the thyristor, and the magnetic latching relay is connected to the magnetic latching coil driving circuit. the

Preferably, the intelligent control and protection composite switch further includes a door indicator light and a state indicator light driving circuit connected to the single-chip microcomputer unit. the

Preferably, the single-chip microcomputer unit is an STC12C series single-chip microcomputer unit. the

Preferably, the communication circuit is a 485 communication circuit. the

Preferably, the thyristor zero-crossing switching circuit is a thyristor zero-crossing switching circuit based on the MOC3083 chip, and the thyristor zero-crossing switching circuit uses an integrated circuit with a Schmitt trigger to drive the MOC3083 chip , and the core inductor is connected in series with the thyristor. the

Preferably, the full-wave detection circuit includes a current transformer to sample the current state of each phase in real time. the

Preferably, the single-chip microcomputer unit performs real-time current analysis and transmits the analysis result to the controller or the host computer through the communication circuit. the

Preferably, the door panel indicator light driving circuit includes a ULN2003A chip and a MOC3083 chip. the

Through the above-mentioned technical solutions, the problems of unstable zero-crossing trigger circuit of thyristor, damage of thyristor, and sintering of magnetic holding contacts have been completely solved. At the same time, functions such as adaptive control of thyristor conduction time and real-time monitoring of each phase current have been added. Make accurate control and protection through real-time current analysis, and transmit it to the controller and host computer through the communication circuit to provide accurate composite switch and capacitor state information. At the same time, in the case of a fault, in addition to its own maximum protection, it also provides the upper computer or controller with the current operating information of the composite switch and capacitor through the communication circuit, so that it can be repaired and replaced in time when the fault occurs. Therefore, the intelligent composite switch of the utility model not only solves the breakdown of the thyristor and the sintering of the magnetic latching relay, but also increases the undercurrent, overcurrent protection, capacitor state diagnosis and fault reminder functions that the current domestic composite switch does not have. Intelligent control and protection composite switch. In addition, the intelligent composite switch of the utility model is low in cost and has wide application prospects. Other features and advantages of this utility model will be described in detail in the following specific embodiments. the

Description of drawings

The accompanying drawings are used to provide a further understanding of the utility model, and constitute a part of the description, and are used to explain the utility model together with the specific embodiments of the utility model, but do not constitute a limitation to the utility model. In the attached picture:

Fig. 1 is the overall block diagram of the intelligent control and protection composite switch of the specific embodiment of the present invention;

Fig. 2 is the single-chip microcomputer unit of the STC12C series adopted by the intelligent control and protection composite switch of the specific embodiment of the present utility model;

Fig. 3 is the thyristor zero-crossing switching circuit of the intelligent control and protection compound switch of the specific embodiment of the utility model;

Fig. 4 is the silicon controlled rectifier and protection device thereof of the intelligent control and protection compound switch of the specific embodiment of the present invention;

Fig. 5 is a schematic diagram of the current waveform of the intelligent control and protection composite switch of the present invention when there is no protection;

Fig. 6 is the current full-wave detection circuit of the intelligent control and protection compound switch of the specific embodiment of the present invention;

Fig. 7 is the schematic diagram of the door panel indicator light and the state indicator light drive circuit of the intelligent control and protection composite switch of the specific embodiment of the present invention;

Fig. 8 is the entity schematic diagram of the control circuit printed circuit board of the specific embodiment of the present invention;

Fig. 9 is the entity schematic diagram of the composite switching power device circuit printed circuit board of the specific embodiment of the present invention;

Fig. 10 is the entity schematic diagram of the 485 communication interface circuit printed circuit board of the specific embodiment of the present utility model; And

Fig. 11 is a physical schematic diagram of the magnetic latching relay driving circuit printed circuit board according to the specific embodiment of the present invention. the

Detailed ways

In order to facilitate the understanding of those skilled in the art, a further description will be made below in conjunction with the specific embodiments of the present invention and the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the utility model, and are not intended to limit the utility model. In the following description of the specific embodiments of the present invention, the description of the relevant circuits is only exemplary and not restrictive. Within the scope of the technical concept of the present invention, those skilled in the art can think of many simple deformations. The key technical requirement of the new intelligent control and protection composite switch lies in the connection structure of the relevant circuits. the

As shown in Figure 1, the basic technical solution of the utility model discloses an intelligent control and protection composite switch for reactive power compensation switching capacitors. The intelligent control and protection composite switch includes a single-chip microcomputer unit, a silicon controlled Switching circuit, anti-parallel one-way thyristor and its protection device, magnetic latching coil drive circuit and its magnetic latching relay, full-wave detection circuit, and communication circuit, wherein, the thyristor zero-crossing switching circuit, magnetic The holding coil drive circuit, the full-wave detection circuit and the communication circuit are connected to the single-chip microcomputer unit, the anti-parallel unidirectional thyristor and its protection device are connected to the zero-crossing switching circuit of the thyristor, and the magnetic latching relay Connected to the magnetic holding coil driving circuit. the

On the basis of the above-mentioned basic technical solution, preferably, the communication circuit can use a 485 communication circuit, through which the upper computer or controller can be provided with the operation information of the current composite switch and capacitor, so as to obtain timely maintenance and replacement in case of failure . 2500V isolated power supply and optocoupler isolation circuit can be used in the 485 communication circuit to ensure the reliability of 485 communication, and the ModBus protocol is used to communicate with the host computer or controller to ensure the accuracy of receiving and sending data (for details, please refer to the 485 communication shown in Figure 10). physical schematic of the interface circuit printed circuit board). the

In addition, preferably, the intelligent control and protection composite switch of the present invention may also include a door panel indicator light drive circuit and a status indicator light drive circuit, so as to indicate the intelligent composite switch of the present utility model through the door panel indicator light and the status indicator light working status. the

The various components and functions of the intelligent control and protection composite switch of the present invention will be described in detail below in conjunction with the accompanying drawings. the

As shown in Figure 2, the single-chip microcomputer unit can adopt the single-chip microcomputer unit of STC12C series, and the inventor has selected STC's latest 1T enhanced 8051 single-chip microcomputer as the microprocessor, which can guarantee higher anti-interference ability at a lower price and reliability, through the software programming of the single chip microcomputer to switch the thyristor and the magnetic latching relay, and through the sampling current for switching state analysis, capacitor capacity analysis, overcurrent, undercurrent, phase loss analysis, etc., if a fault occurs Composite switches and capacitors will be protected to the greatest extent possible. In addition, in the preferred mode, the single-chip unit communicates with the controller through the 485 communication circuit, receives the switching signal and sends out the working status (working current, capacitor status and some fault indicators, etc.), so that it can be observed on the controller to the working state of the composite switch and capacitor. the

As shown in Figure 3, the MOC3083 is used in the thyristor zero-crossing switching circuit to control the on and off of the anti-parallel unidirectional thyristor higher than 1600v. Since the MOC3083 uses the voltage zero-crossing point to trigger the photo-silicon, the withstand voltage is only 800V, so two MOC3083 are used in series, and the off-state withstand voltage of the two MOC3083 is balanced through a voltage equalizing resistor. The resistance selection should not be too large or too small. , And it will cause the fault to not be triggered for 10ms when it is cut off, which will cause fatal damage to the magnetic latching relay. It is found in the experiment that it is best to use a resistance of about 1M and 0.5W. The drive MOC3083 adopts 7414 integrated circuit with Schmitt trigger, which can well prevent the phenomenon of false triggering of MOC3083 caused by the fluctuation of the composite switching DC power supply. the

At present, many composite switches use bidirectional thyristors in series, which is a very harmful practice. Triacs are not as good as anti-parallel unidirectional thyristors in terms of withstand voltage, current resistance, voltage changes, and current changes. Customized silicon controlled rectifiers with high withstand voltage, high voltage change rate, and high current change rate with domestic manufacturers. However, since the load is a capacitor, a unidirectional thyristor transitions from conduction to cutoff during commutation (as shown in Figure 5), and the excess electrons inside will form a large reverse current under the pull of reverse voltage , It is very easy to cause damage to the thyristor. The inventor has produced a cost-effective magnetic core inductor connected in series with the thyristor through large-scale experiments (as shown in Figure 4), which has solved the problem of damage to the thyristor. the

As shown in Figure 6, the current full-wave detection circuit is used to detect the working state of the composite switch in real time and provide the maximum protection function. Among them, the high-precision current transformer is used to sample the current state of each phase in real time, and the full-wave detection circuit can improve detection Performance, the sampling current is analyzed by the single-chip microcomputer to obtain the operation status of the thyristor and the relay, the working current, the capacity of the capacitor, whether there is an abnormality in the item, etc. More importantly, the full-wave detection circuit detects the three-phase current, supplies it to the microcontroller for real-time analysis, and obtains information such as the thyristor, magnetic latching working status, capacitance capacity and current (normal, overcurrent, undercurrent and phase loss), and Make the best control and protection application, and the application prolongs the life of the indicator light. Also, since many times a composite switch or capacitor goes bad, no one knows. And this composite switch will pass the analysis result to the controller and the host computer through the 485 communication interface, which can make the staff find the fault well and repair or replace it. In addition, because the capacitor capacity will continue to decay with the passage of time, the composite switch will continuously send the latest capacity data to the controller through capacity analysis. On the one hand, the controller can obtain the most accurate capacitor capacity and improve the compensation accuracy. Therefore, in the event of a fault, in addition to its maximum protection, it also provides the upper computer or controller with the current operating information of the composite switch and capacitor through the 485 communication circuit, so that it can be repaired and replaced in time when a fault occurs. the

As shown in Figure 7, ULN2003A plus MOC3083 is used in the external 220V door panel indicator drive circuit to drive the door panel indicator light, which avoids the reduction of the life of the indicator light caused by the use of relays. We ensure that the indicator light is turned on and off in the zero-crossing state , improve the service life of the door indicator light. In addition, the figure also shows the status indicator light on the composite switch, which is mainly used to indicate the current working status of the composite switch. The green light is in the state of power-on and non-closed, the red light is in the state of power-on and closed, and the light is not on when it is faulty. state. the

The magnetic latching coil drive circuit can use the domestic Belling 8023 special magnetic latching relay drive chip (see the physical schematic diagram of the magnetic latching relay drive circuit printed circuit board shown in Figure 11), which simplifies the drive design, improves reliability, and can guarantee 50ms Effectively closes and opens the magnetic latching relay within. The magnetic latching relay can use the domestic Best 902 series magnetic latching relay. As long as the thyristor is zero-crossed when the magnetic latching relay is closed and disconnected, the service life of the magnetic latching relay can reach more than 100,000 times, but if the thyristor When there is no conduction or incomplete conduction, the magnetic latching relay is closed under the rated current. After hundreds of tests, the silver contacts will burn or stick together. Therefore, the use of magnetic latching relays must ensure that the thyristor works normally. the

The working principle of the utility model is that after power on, the three-phase current enters the monitoring state immediately, analyzes the current situation every millisecond, and sends the working state information to the controller no matter whether it is normal or not, so that the controller can record the operation status of the composite switch , in order to make the optimal switching plan. When the input signal from the controller is received, the thyristor is first triggered by the voltage zero crossing, and the current is monitored to determine whether the current is normal. If it is normal, the magnetic latching relay is activated. After receiving the cutting signal from the controller, first start the SCR trigger circuit, then cut off the magnetic latching relay, and then make the SCR current zero-crossing to close. Regardless of whether the composite switch is closed or disconnected, the current monitoring is always in progress. If there is any abnormal situation, the composite switch will enter the protection state. the

In addition, Fig. 8 and Fig. 9 also show the physical schematic diagram of the control circuit printed circuit board of the composite switch of the present invention and the physical schematic diagram of the printed circuit board of the power device circuit, wherein the connection positions of the relevant leads are shown in detail, for those skilled in the art Personnel reference. the

It should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner, which also fall within the scope of the present utility model. In addition, various implementations of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention. the

The preferred embodiment of the utility model has been described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the specific details of the above-mentioned embodiment, and within the scope of the technical concept of the utility model, the technical solution of the utility model can be carried out in many ways. These simple modifications all belong to the protection scope of the present utility model. The protection scope of the utility model is defined by the claims. the

Claims (8)

1. An intelligent control and protection composite switch is characterized in that the intelligent control and protection composite switch comprises a single-chip microcomputer unit, a thyristor zero-crossing switching circuit, an anti-parallel unidirectional thyristor and its protection device, a magnetic Holding coil driving circuit and its magnetic holding relay, full-wave detection circuit and communication circuit, wherein the thyristor zero-crossing switching circuit, magnetic holding coil driving circuit, full-wave detection circuit and communication circuit are connected to the single-chip microcomputer unit , the anti-parallel unidirectional thyristor and its protection device are connected to the zero-crossing switching circuit of the thyristor, and the magnetic latching relay is connected to the magnetic latching coil drive circuit. 2. The intelligent control and protection composite switch according to claim 1, characterized in that, the intelligent control and protection composite switch also includes a door indicator light and a status indicator driving circuit connected to the single-chip microcomputer unit. 3. The intelligent control and protection compound switch according to claim 1, characterized in that, the single-chip microcomputer unit is a STC12C series single-chip microcomputer unit. 4. The intelligent control and protection composite switch according to claim 1, wherein the communication circuit is a 485 communication circuit. 5. The intelligent control and protection composite switch according to claim 1, characterized in that, the thyristor zero-crossing switching circuit is a thyristor zero-crossing switching circuit based on the MOC3083 chip, and the thyristor The zero-switching circuit uses an integrated circuit with a Schmitt trigger to drive the MOC3083 chip, and uses a magnetic core inductor in series with a thyristor. 6. The intelligent control and protection composite switch according to claim 1, wherein the full-wave detection circuit includes a current transformer to sample the current state of each phase in real time. 7. The intelligent control and protection composite switch according to claim 1, characterized in that, the single-chip microcomputer unit performs real-time current analysis and transmits the analysis result to the controller or the host computer through the communication circuit. 8. The intelligent control and protection composite switch according to claim 2, characterized in that, the door panel indicator light driving circuit includes a ULN2003A chip and a MOC3083 chip. the

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