CN112018782A

CN112018782A - Intelligent capacitor with synchronous fling-cut switch

Info

Publication number: CN112018782A
Application number: CN202010810049.9A
Authority: CN
Inventors: 刘曙光; 陈小龙; 陈志�; 王泽超
Original assignee: Huangshan University
Current assignee: Huangshan University
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2020-12-01

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

Intelligent capacitor with synchronous fling-cut switch

Technical Field

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

Background

At present, capacitor switching mainly has three modes: (1) an alternating current contactor is used as a switching switch, inrush current can be generated when a capacitor is put into the switching switch, and contacts are easy to bond and difficult to pull open; (2) the thyristor is used as a switching switch, has the capabilities of voltage zero-crossing conduction and current zero-crossing turn-off, can limit the switching-on inrush current, but has conduction voltage drop during conduction to generate larger loss and heating phenomena; (3) the composite switch is used as a switching switch and is formed by connecting a thyristor and a magnetic latching relay in parallel, so that the zero-crossing switching-in and the zero-crossing cutting-off of the voltage of the capacitor can be realized, but the composite switch does not have the functions of fault self-diagnosis and self-display, and does not have the protection function on the switch and the capacitor.

Because reactive power can cause the loss of a power distribution network and the voltage drop of a power receiving end, the electric energy utilization rate is greatly reduced, and the power supply quality is seriously influenced, so that a reactive compensation device is arranged at a proper position in a circuit to become a necessary means for reducing reactive loss.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides an intelligent capacitor with a synchronous switching switch, and solves the problems that in the existing low-voltage distribution network, a reactive compensation method of parallel capacitors is adopted, large inrush current and harmonic waves are easily generated due to improper switching method and time, and the use requirement of reactive compensation is difficult to meet.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: the utility model provides an intelligent capacitor with synchronous on-off switch, includes microprocessing unit, synchronous switch circuit and condenser, the microprocessing unit includes voltage, current signal conditioning circuit, electric energy detection circuitry, microprocessor, zero passage detection circuit, LCD display circuit, LED indicating circuit, RS485 communication circuit, the synchronous switch circuit includes thyristor trigger circuit, thyristor and magnetic latching relay, the thyristor is parallelly connected with magnetic latching relay.

Preferably, the synchronous switch circuit and the capacitor are connected in series with an alternating current of 220V.

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

(III) advantageous effects

The invention provides an intelligent capacitor with a synchronous fling-cut switch. Has the following beneficial effects:

the intelligent capacitor with the synchronous switching switch is integrated with a compensation capacitor by adopting a synchronous switching technology based on a magnetic latching relay, and the micro-processing unit finishes accurate zero-crossing synchronous switching by prejudging the time of voltage and current zero crossing points, namely, the magnetic latching relay can be put in advance before the voltage zero crossing point to ensure that the contact of the magnetic latching relay is just closed at the time of voltage zero crossing, thereby realizing inrush current-free input of the capacitor, and the magnetic latching relay can be cut off in advance before the current zero crossing point to ensure that the contact of the magnetic latching relay is just disconnected at the time of current zero crossing, thereby realizing arc-free cutting of the capacitor and achieving real zero-crossing switching. The intelligent capacitor also has the self-diagnosis function of faults such as three-phase undervoltage, overvoltage, overcurrent, phase failure and the like, can well meet the requirement of a low-voltage distribution network on reactive compensation, can meet the requirement of large load change of a power grid on the reactive compensation rapidly, and is suitable for various power utilization occasions.

Drawings

FIG. 1 is a schematic diagram of a microprocessor unit of the present invention;

FIG. 2 is a schematic diagram of a synchronous switching circuit of the present invention;

fig. 3 is a flow chart of the capacitor synchronous switching software of the invention.

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

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides a technical solution: the utility model provides an intelligent capacitor with synchronous on-off switch, includes microprocessing unit 1, synchronous switch circuit 2 and condenser 3, microprocessing unit 1 includes voltage, current signal conditioning circuit 101, electric energy detection circuitry 102, microprocessor 103, zero cross detection circuitry 104, LCD display circuit 105, LED indicating circuit 106, RS485 communication circuit 107, synchronous switch circuit 2 includes thyristor trigger circuit 201, thyristor 202 and magnetic latching relay 203 are parallelly connected.

The synchronous switch circuit 2 and the capacitor 3 are connected in series with an alternating current of 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, a micro-processing unit 1 is utilized to send voltage and current signals into an electric energy detection circuit 102 after signal conditioning 101, the electric energy detection circuit 102 finishes voltage and current sampling and corresponding electric energy parameter conversion and then sends the signals into a microprocessor 103, meanwhile, a zero-crossing detection circuit 104 finishes voltage and current phase detection and zero-crossing judgment and then sends a zero-crossing state into the microprocessor 103, the microprocessor 103 carries out drive control on a thyristor trigger circuit 201 through logic judgment, in addition, the microprocessor 103 also finishes the calculation of voltage and current effective values of apparent power, reactive power, active power and power factor on data sent by the electric energy detection circuit 102, and displays the operation working conditions in real time through an LCD display circuit 105 and an LED indicating circuit 106,

then, as shown in fig. 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 sends a conduction command to the thyristor trigger circuit 201, the thyristor 202 is conducted by the trigger circuit 201, the magnetic latching relay 203 connected in parallel with the thyristor is then conducted, and the capacitor 3 is connected with the alternating current 220V single-phase loop; when the micro-processing unit 1 receives the current zero-crossing signal from the zero-crossing detection circuit 104, it sends out a turn-off command to the thyristor trigger circuit 201, the thyristor 202 is turned off by the trigger circuit 201, the magnetic latching relay 203 connected in parallel with the thyristor is then turned off, the capacitor 3 is disconnected from the main circuit,

as shown in fig. 3, when the capacitor is synchronously switched, the synchronous switching software flow is as follows:

step S101: completing initialization of voltage, phase sequence and switch state, and setting a flag bit;

step S102: detecting a synchronous signal before the switch is put into operation;

step S103: the intelligent capacitor is self-diagnosed when the fault occurs, and if the fault occurs, fault processing is carried out;

step S104: if no fault exists, detecting the switching signal state;

step S105: judging whether the voltage and current signals are zero-crossing;

step S106: if the voltage or current signal crosses zero, switching operation is executed, namely, the compensation capacitor is switched on or off by controlling the on-off of the thyristor and the magnetic latching relay;

step S107: the intelligent capacitor fault self-diagnosis judges whether a fault exists, if so, a fault LED indicating lamp is lightened, and the combination switch exits;

step S108: if no fault exists, the LED indicator lamp is lightened, and the state of the synchronous signal after switching of the switch is continuously detected;

step S109: the intelligent capacitor fault self-diagnosis judges whether a fault exists, if so, a fault LED indicating lamp is lightened, and the combination switch exits;

step S110: if no fault exists, detecting a switching signal;

step S111: if the switching signal is required to be continuously maintained, the original switching state is continuously maintained; and if the switching signal is not required to be continuously maintained, the compound switch is quitted, and the program returns.

The intelligent capacitor can be assembled in a building block mode in the electrical cabinet to form a reactive automatic compensation complete device, the structural mode of the traditional automatic compensation device is broken through, the intelligent capacitor has excellent functions such as capacitor zero-crossing switching and the like, and has the characteristics of simple structure, easiness in production, good capacity adjustability, convenience in operation and maintenance and the like, and because the intelligent capacitor has operation condition indication and display and can be manually operated, a state indicator lamp and a manual operation switch can not be mounted on the cabinet.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation. The use of the phrase "comprising one of the elements does not exclude the presence of other like elements in the process, method, article, or apparatus that comprises the element.

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

Claims

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).