CN2295288Y

CN2295288Y - Reactive power automatic compensating box for civil buildings

Info

Publication number: CN2295288Y
Application number: CN 97210028
Authority: CN
Inventors: 袁从武
Original assignee: YANENG ELECTRIC-APPLIANCE Co Ltd CHONGQING
Current assignee: YANENG ELECTRIC-APPLIANCE Co Ltd CHONGQING
Priority date: 1997-03-28
Filing date: 1997-03-28
Publication date: 1998-10-21
Anticipated expiration: 2007-03-28

Abstract

The utility model relates to a reactive power automatic compensating box for civil buildings. The utility model is characterized in that the utility model comprises a reactive power testing circuit, an over voltage and under voltage circuit, a capacitor protection mechanism, a control logic circuit, and a switching operating mechanism, wherein, the reactive power testing circuit comprises a voltage signal phase shift circuit and a multiplier circuit, the capacitor protection mechanism is composed of three parts, such as a capacitor losses testing circuit, a capacitor inner part component overheat protection circuit, and a capacitor breakdown short circuit protection part, and a compensation capacitor is a fully dry type integrated self healing capacitor. The utility model uses the cross product of line current and SINphi as the basis of controlling the switch of the compensating capacitor, and the compensation precision is obviously improved. The utility model is especially suitable for objects, such as the civil buildings having the characteristics that the change in load is large, and the power factor fluctuation is violent.

Description

Civil buildings reactive power automatic compensation case

The circuit arrangement that relates to power supply or distribution of the present utility model, particularly a kind of civil buildings reactive power automatic compensation case.

Along with the raising of development and national economy and people's living standard, household electrical appliance enter huge numbers of families fast, and civilian electric weight increases considerably, and according to the authoritative department statistics, town dweller's electricity consumption in 95 years has accounted for more than 15% of city electricity consumption total amount.On the other hand, most civil electric appliances are inductive load, and power factor generally is lower than 0.75, have not only taken power supply unit capacity at full stretch, and have caused a large amount of electric energy and the loss of voltage, cause supply power voltage on the low side, influence normal power supply.Therefore the civil buildings electric power system being carried out reactive power compensation has been imperative.

The reactive power compensation device that is used for civil buildings in the prior art uses shunt capacitor bar none, most reactive power compensation devices are selected the input of capacitor or are cut off electrical network according to supply line's power factor, and there is the problem of following three aspects in they:

1. civilian electric loading is small and scattered, starts and stop frequent.Therefore, reaction output power on the line is very big with seasonal variations in time, and the electricity consumption electric current when its peak and low ebb can differ tens of times to hundreds of times.Simultaneously, power factor also fluctuates acutely, as to establish line current be I, and voltage is V, and power-factor angle is, active power is P, and reactive power is Q, then

P＝V·I·COSΦ

Q＝V·I·SINΦ

The purpose of reactive power compensation is to offset Q, and when angle one timing, Q is directly proportional with line current I.Therefore, as with the COS Φ control switching variable of capacitor by way of compensation, the undercompensation when overcompensation in the time of certainly will causing low power consumption and peak of power consumption.In some cases, even can cause the controlling organization concussion, the frequent switching capacitor influences power grid operation.

Chinese patent CN89208932.6 proposes directly to detect the peak value of each cycle of reactive current of inductive load, CN90225832.x utilizes the total idle amount of reactive energy-meter measurement circuitry, but have complex circuit, cost is too high, only can be used for 100KVA above industrial object or high-low pressure transformer and distribution station.

2. the industry compensation is bigger with the shunt capacitor volume, and the separate unit capacity is big, is used for the civil buildings compensation and certainly will causes the capacitor switching step pitch big.Because the capacity of short circuit of civil buildings distribution system is little, shoving of large value capacitor switching moment causes serious impact to electrical network, makes air switch tripping operation or blown fuse, influences normal electricity consumption.

Since compensation with capacitor to overvoltage, to cross short circuit relatively more responsive, the fault probability is big, when loss increases, generates heat when serious, may set off an explosion.Therefore, industrial reactive power compensation device is all sent out the staff on duty monitoring, and the necessary unattended operation system of civilian reactive power compensation device, so particularly important to the automatic protection of capacitor.Existing product a protection to service conditions such as voltage, electric currents, and do not consider capacitor after long-term the use, loss increases, and the blast of still may generating heat under regular service conditions stays great potential safety hazard.

The purpose of this utility model is to change at appliance load violent, and the characteristics that peak of power consumption and low ebb differ greatly are control variables with the product of line current I and SIN Φ, that is is that reactive power with circuit is a control variables.Direct measurement circuitry electric current I of a kind of employing controlling organization and SIN Φ are provided, and carry out multiplying by multiplier, with the foundation of product as capacitor switching, can obviously improve the accuracy of compensation, can overcome the prior art above shortcomings, have good practicability and fail safe, can obtain the civil buildings reactive power automatic compensation case of good effect.

Above-mentioned purpose of the present utility model is to realize by such technical scheme, it is a kind of civil buildings reactive power automatic compensation case, comprise casing and building-out capacitor, it is characterized in that: 1. comprise a reactive power testing circuit, it comprises voltage signal phase-shift circuit and multiplier circuit, after 90 ° of phase shifts, multiply each other and obtain reactive power signals through the voltage signal of sensor with current signal, this signal input two is preset with the comparator circuit of reactive power higher limit and lower limit, exports switching and excision signal respectively by it; 2. comprise an overvoltage and under voltage protection circuit, after peak detection and filtering, import two comparators that are preset with upper voltage limit value and lower limit through the voltage signal of sensor, by its output over-voltage signal or brownout signal; 3. comprise a capacitor protection mechanism, form by condenser loss testing circuit, capacitor inner member overheating protection circuit and capacitor breakdown short-circuit protection three parts, wherein the current transformer in the condenser loss testing circuit detects the current difference signal that capacitor produces because of loss, amplify through active wave detector detection, signal is sent into the comparator that is preset with permission electric current difference upper and lower bound, by its output protection signal, capacitor inner member overheating protection circuit is made of the heat portective switch of connecting with each compensation condenser; 4. comprise a control logic circuit, constitute by the programmable logic array integrated circuit, carry out substep input, excise function step by step by its switching, excision, overvoltage, under voltage, guard signal, and send control signal to switching actuator to input; 5. comprise a switching actuator, constitute by drive circuit driving controllable silicon or contactor; 6. compensation condenser is the integrated self-healing capacitor of dry type, and its inside has 6 or 9 capacitor elements, divides 2 or 3 groups, capacity is equal difference and distributes, adopt the three-phase delta connection, connect the three-phase and four-line electrical network, realize 4-8 step switching by actuator and automatic air circuit breaker.

The embodiment of the indefiniteness that said structure of the present utility model can provide by accompanying drawing further specifies.

The utility model has following accompanying drawing:

Accompanying drawing 1 is circuit theory diagrams of the present utility model;

Accompanying drawing 2 is the electrical block diagram of embodiment of the present utility model.

Referring to accompanying drawing: the civil buildings reactive power automatic compensation case among the figure, 1. comprise a reactive power testing circuit, it comprises voltage signal phase-shift circuit and multiplier circuit, by two operational amplifier U1-1, U1-2 (LM339), resistance R 1～R6, capacitor C 1, C2 forms, through the voltage signal of sensor through R6, after 90 ° of phase shifts of rc phase shifter circuit that C3 forms, current signal is carried out the PWM modulation, after amplifying, multiply each other with current signal and obtain reactive power signals, this signal input two is preset with the comparator circuit of reactive power higher limit and lower limit, exports switching and excision signal respectively by it; 2. comprise an overvoltage and under voltage protection circuit, after peak detection and filtering, import two comparator U1-3, the U2-1 (LM324) that are preset with upper voltage limit value and lower limit through the voltage signal of sensor, by its output over-voltage signal or brownout signal; 3. comprise a capacitor protection mechanism, by the condenser loss testing circuit, capacitor inner member overheating protection circuit and capacitor breakdown short-circuit protection three parts are formed, wherein the current transformer LB in the condenser loss testing circuit detects the current difference signal that capacitor produces because of loss, through U2-4, R27, R26, R28, C6, D3 forms active wave detector detection and amplifies, signal is sent into the comparator U1-4 that is preset with permission electric current difference upper and lower bound, by its output protection signal, capacitor inner member overheating protection circuit is made of the heat portective switch Rt1-Rt7 that connects with each compensation condenser, when the capacitor heating surpasses the heat portective switch set point, switch disconnects, remove the power supply of compensation condenser, the capacitor breakdown short-circuit protection adopts automatic air circuit breaker K; 4. comprise a control logic circuit, 16V8 constitutes by the programmable logic array integrated circuit, by its switching to input, excision, overvoltage, under voltage, guard signal carries out substep input, substep excises function, and by its 18,19 pin send control signal to switching actuator, circuit adopts the time-delay switching technology simultaneously, its clock pulse is 1,60Hz and 50Hz, the former is produced by the NE555 integrated circuit, the latter is produced by line voltage distribution, be used to realize the discharge time-delay of capacitor, in addition, when the compensation condenser that drops into switches between the different capabilities group, the generation of avoiding switching to shove; 5. comprise a switching actuator, drive circuit drives controllable silicon by triode T1, T2 or contactor constitutes, for jumbo compensation condenser, drive auxiliary relay G1, G2 by T1, T2, promote A.C. contactor G2, G3 again and drop into or excise compensation condenser C; 6. compensation condenser C is the integrated self-healing capacitor of dry type, its inside has 6 or 9 capacitor elements, divide 2 or 3 groups, capacity is equal difference and distributes, for example: one group 3,6 of another groups, all adopt the three-phase delta connection, its capacity is 3KVar and 6KVar, connects the three-phase and four-line electrical network by A.C. contactor G3, G4 and automatic air circuit breaker K, realizes 4-8 step switching.

The utility model is following significant advantage owing to described structure has:

1. the foundation take the product of line current and SIN Φ as the control and compensation capacitor switching, Obviously improved the compensation degree of accuracy, very suitable this type load of civil buildings changes greatly, power The object that the factor fluctuation is violent;

2. have overvoltage, overcurrent and temperature rise and cross high multiple auto-protection function, because Designed capacitor incipient fault detection function, prevented the capacitor long-time running after loss increase Big and the combustion explosion accident that produces guarantees the security of product;

3. adopt the time-delay switching technology, reduced the switching step pitch, improved compensation precision, reduced moment impact electrical network;

4. circuit structure is simple, and dependable performance is with low cost.

The civil buildings reactive power automatic compensation that is used for of the present utility model has good practicability and fail safe.

Claims

1. civil buildings reactive power automatic compensation case, comprise casing and building-out capacitor, it is characterized in that: (1). comprise a reactive power testing circuit, it comprises voltage signal phase-shift circuit and multiplier circuit, after 90 ° of phase shifts, multiply each other and obtain reactive power signals through the voltage signal of sensor with current signal, this signal input two is preset with the comparator circuit of reactive power higher limit and lower limit, exports switching and excision signal respectively by it; (2). comprise an overvoltage and under voltage protection circuit, after peak detection and filtering, import two comparators that are preset with upper voltage limit value and lower limit through the voltage signal of sensor, by its output over-voltage signal or brownout signal; (3). comprise a capacitor protection circuit, form by condenser loss testing circuit, capacitor inner member overheating protection circuit and capacitor breakdown short-circuit protection three parts, wherein the current transformer in the condenser loss testing circuit detects the current difference signal that capacitor produces because of loss, amplify through active wave detector detection, signal is sent into the comparator that is preset with permission electric current difference upper and lower bound, by its output protection signal, capacitor inner member overheating protection circuit is made of the heat portective switch of connecting with each compensation condenser; (4). comprise a control logic circuit, constitute by the programmable logic array integrated circuit, carry out substep input, excise function step by step by its switching, excision, overvoltage, under voltage, guard signal, and send control signal to switching actuator to input; (5). comprise a switching actuator, constitute by drive circuit driving controllable silicon or contactor; (6). compensation condenser is the dry type integrated capacitor, and its inside has 6 or 9 capacitor elements, divides 2 or 3 groups, capacity is equal difference and distributes, adopt the three-phase delta connection, connect the three-phase and four-line electrical network, realize 4-8 step switching by actuator and automatic air circuit breaker.