CN112018782A - Intelligent capacitor with synchronous fling-cut switch - Google Patents

Abstract

The invention discloses an intelligent capacitor with a synchronous switching switch, which comprises a micro-processing unit, a synchronous switching circuit and a capacitor, wherein the micro-processing unit comprises a voltage and current signal conditioning circuit, an electric energy detection circuit, a microprocessor, a zero-crossing detection circuit, an LCD (liquid crystal display) circuit, an LED (light emitting diode) indicating circuit and an RS485 communication circuit, the synchronous switching circuit comprises a thyristor trigger circuit, a thyristor and a magnetic latching relay, the thyristor is connected with the magnetic latching relay in parallel, and the synchronous switching circuit and the capacitor are connected with an alternating current 220V in series. The synchronous switching switch and the capacitor are integrated, so that the inrush current and the electric arc generated by the power capacitor during switching are greatly reduced, the safety and the reliability of the capacitor are improved, the self-diagnosis function of faults such as three-phase undervoltage, overvoltage, overcurrent and phase failure is realized, and the requirement of a low-voltage distribution network on reactive compensation can be well met.

Description

A smart capacitor with synchronous switching switch

technical field

The invention relates to the technical field of power reactive power compensation, in particular to an intelligent capacitor with a synchronous switching switch.

Background technique

At present, there are three main ways of switching capacitors: (1) AC contactors are used as switching switches, inrush current will be generated when the capacitors are put in, and the contacts are easy to stick and not easily pulled apart; (2) Thyristors are used as switching switches, which have The voltage zero-crossing turn-on and current zero-crossing turn-off capability can limit the closing inrush current, but there will be a conduction voltage drop when it is turned on, resulting in large losses and heat generation; (3) Using a composite switch as a switching switch, it It is composed of a thyristor and a magnetic latching relay in parallel, which can realize the zero-crossing of the capacitor voltage and the zero-crossing of the current, but it does not have the functions of fault self-diagnosis and self-display, and has no protection function for switches and capacitors.

Because reactive power will cause the loss of distribution network and the voltage drop of the receiving terminal, the utilization rate of electric energy will be greatly reduced and the quality of power supply will be seriously affected. Therefore, installing a reactive power compensation device at an appropriate position in the line has become a necessary means to reduce reactive power loss. , In the low-voltage distribution network, the method of parallel capacitors is generally used for reactive power compensation, but if the method and timing of switching are not appropriate, large inrush currents and harmonics will be generated.

SUMMARY OF THE INVENTION

(1) Technical problems solved

Aiming at the deficiencies of the prior art, the present invention provides a smart capacitor with a synchronous switching switch, which solves the problem that in the current low-voltage power distribution network, the reactive power compensation method using parallel capacitors is prone to inconsistencies in the switching method and timing. Appropriately, large inrush current and harmonics will be generated, and it is difficult to meet the needs of reactive power compensation.

(2) Technical solutions

In order to achieve the above purpose, the present invention is achieved through the following technical solutions: a smart capacitor with a synchronous switching switch, comprising a micro-processing unit, a synchronous switching circuit and a capacitor, and the micro-processing unit includes a voltage and current signal conditioning circuit , power detection circuit, microprocessor, zero-crossing detection circuit, LCD display circuit, LED indication circuit, RS485 communication circuit, the synchronous switch circuit includes a thyristor trigger circuit, a thyristor and a magnetic latching relay, the thyristor is connected in parallel with the magnetic latching relay .

Preferably, the synchronous switch circuit and the capacitor are connected in series with AC 220V.

Preferably, a current transformer and a voltage sampler are arranged outside the voltage and current signal conditioning circuit.

(3) Beneficial effects

The present invention provides an intelligent capacitor with a synchronous switching switch. Has the following beneficial effects:

The smart capacitor with synchronous switching switch adopts the synchronous switching technology based on magnetic latching relay and integrates it with the compensation capacitor. Zero synchronous switching, that is, the magnetic latching relay can be switched on in advance before the voltage zero-crossing point, so that its contacts are just closed at the time of the voltage zero-crossing, so as to realize the inrush-free switching of the capacitor, and the magnetic latching can be cut off in advance before the current zero-crossing point. The relay makes its contacts disconnected at the moment when the current crosses zero, thereby realizing the arc-free cutting of the capacitor and achieving true zero-crossing switching. Compared with the traditional reactive power compensation method, it can greatly reduce the power capacitor in the switching The inrush current and arc generated during the switch further improve the safety and reliability of the capacitor. This smart capacitor also has three-phase undervoltage, overvoltage, overcurrent, and lack of phase fault self-diagnosis functions, which can be well adapted to low voltage. The demand for reactive power compensation in the distribution network can meet the needs of large changes in grid load and rapid reactive power compensation, and is suitable for various power consumption occasions.

Description of drawings

Fig. 1 is the principle diagram of the micro-processing unit of the patent of the present invention;

Fig. 2 is the schematic diagram of the synchronous switch circuit of the patent of the present invention;

Fig. 3 is the flow chart of the capacitor synchronous switching software of the patent of the present invention.

In the figure: 1 microprocessor unit, 101 voltage and current signal conditioning circuit, 102 electric energy detection circuit, 103 microprocessor, 104 zero-crossing detection circuit, 105 LCD display circuit, 106 LED indication circuit, 107 RS485 communication circuit, 2 synchronous switch Circuit, 201 thyristor trigger circuit, 202 thyristor, 203 magnetic latching relay, 3 capacitors.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1-3, the present invention provides a technical solution: an intelligent capacitor with a synchronous switching switch, comprising a micro-processing unit 1, a synchronous switching circuit 2 and a capacitor 3, and the micro-processing unit 1 includes voltage and current signals Conditioning circuit 101, power detection circuit 102, microprocessor 103, zero-crossing detection circuit 104, LCD display circuit 105, LED indication circuit 106, RS485 communication circuit 107, synchronous switch circuit 2 including thyristor trigger circuit 201, thyristor 202 and magnetic latch The relay 203 and the thyristor 202 are connected in parallel with the magnetic latching relay 203 .

Synchronous switch circuit 2 and capacitor 3 are connected in series with AC 220V.

A current transformer and a voltage sampler are arranged outside the voltage and current signal conditioning circuit 101 .

When in use, as shown in FIG. 1 using the microprocessor unit 1, the voltage and current signals are sent to the electric energy detection circuit 102 after the signal conditioning 101. The electric energy detection circuit 102 completes the voltage and current sampling and the corresponding electric energy parameter conversion and then sends it to the microprocessor 103. At the same time, the zero-crossing detection circuit 104 sends the zero-crossing state to the microprocessor 103 after completing the voltage and current phase detection and zero-crossing judgment. It is also necessary to complete the calculation of apparent power, reactive power, active power, and power factor voltage and current RMS for the data sent through the power detection circuit 102, and display the operating conditions in real time through the LCD display circuit 105 and the LED indication circuit 106. display,

Then, as shown in Figure 2, the synchronous switch circuit 2 is connected in series with the capacitor 3 to complete the switching of the compensation capacitor. After receiving the voltage zero-crossing signal from the zero-crossing detection circuit 104, the micro-processing unit 1 issues a turn-on command to the thyristor trigger circuit 201, The trigger circuit 201 turns on the thyristor 202, the magnetic latching relay 203 connected in parallel with it is then turned on, and the capacitor 3 is connected with the AC 220V single-phase loop; when the micro-processing unit 1 receives the current zero-crossing signal from the zero-crossing detection circuit 104 , issue a shutdown command to the thyristor trigger circuit 201, the trigger circuit 201 turns off the thyristor 202, the magnetic latching relay 203 connected in parallel with it is then turned off, and the capacitor 3 is disconnected from the main circuit,

As shown in Figure 3, when capacitors are switched synchronously, the software process of synchronous switching is as follows:

Step S101: complete the initialization of the voltage, phase sequence, and switch state, and set the flag bit;

Step S102: Detecting the synchronization signal before the switch is turned on;

Step S103: self-diagnose the fault of the smart capacitor, determine whether there is a fault, and handle the fault if there is a fault;

Step S104: if there is no fault, detect the state of the switching signal;

Step S105: determine whether the voltage and current signals cross zero;

Step S106: if the voltage or current signal crosses zero, the switching operation will be performed, that is, the compensation capacitor will be turned on or off by controlling the on-off of the thyristor and the magnetic latching relay;

Step S107: self-diagnose the fault of the smart capacitor, determine whether there is a fault, if there is a fault, light the fault LED indicator, and the composite switch exits;

Step S108: If there is no fault, turn on the LED indicator, and continue to detect the state of the synchronization signal after the switch is switched on and off;

Step S109: self-diagnose the fault of the smart capacitor, determine whether there is a fault, if there is a fault, light the fault LED indicator, and the composite switch exits;

Step S110: If there is no fault, detect the switching signal;

Step S111 : if the switching signal needs to be maintained, the original state of switching is continued; if the switching signal does not need to be maintained, the composite switch exits, and the program returns.

The smart capacitor can be assembled in building block type in the electrical cabinet to form a complete set of reactive power compensation device, breaking the structure mode of the traditional automatic compensation device, and has excellent functions such as zero-crossing switching of capacitors, as well as simple structure, simple production, and adjustable capacity. It has the characteristics of good performance, convenient operation and maintenance, etc., because each smart capacitor has operating condition indication and display and can be manually switched on and off, so the status indicator and manual operation switch can not be installed on the cabinet.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. without more restrictions. An element defined by the phrase "comprising an... does not preclude the presence of additional identical elements in a process, method, article or apparatus comprising said element".

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

1. The utility model provides an intelligent capacitor with synchronous fling-cut switch, includes microprocessing unit (1), synchronous switch circuit (2) and condenser (3), its characterized in that: the micro-processing unit (1) comprises a voltage and current signal conditioning circuit (101), an electric energy detection circuit (102), a microprocessor (103), a zero-crossing detection circuit (104), an LCD display circuit (105), an LED indicating circuit (106) and an RS485 communication circuit (107), the synchronous switch circuit (2) comprises a thyristor trigger circuit (201), a thyristor (202) and a magnetic latching relay (203), and the thyristor (202) is connected with the magnetic latching relay (203) in parallel.

2. The intelligent capacitor with the synchronous switching switch of claim 1, wherein: the synchronous switch circuit (2) and the capacitor (3) are connected with an alternating current 220V in series.

3. The intelligent capacitor with the synchronous switching switch of claim 1, wherein: and a current transformer and a voltage sampler are arranged outside the voltage and current signal conditioning circuit (101).

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