CN1003028B - Automatic compensation control method and compensation system for imaginary power - Google Patents

Abstract

The present invention relates to an automatic compensation control method for reactive power, and a compensation system. In the control method provided by the present invention, the voltage of an electric network and current signals are obtained by the conventional measuring means, and the switching and the prediction of a compensation device are controlled and the ineffective switching action of the compensation device is eliminated by signal treatment on the basis of the reactive power of the electric network. The compensation system using the method is composed of the main line of the electric network, the compensation device, a control executing device, a signal detector and a control circuit, wherein the control circuit comprises the sections of signal conversion, operating control, COSphi digital display and output expansion driving. The present invention is used for the reactive power compensation of electric networks with high voltage and low voltage and the digital display of the values of power factors.

Description

Reactive power automatic compensation control method and bucking-out system

The invention belongs to the power system reactive power compensation technique, particularly with electric capacity, inductance be compensating device, can eliminate the compensating device reactive power compensation system of throw in-of oscillation repeatedly.

The compensation of power system reactive power, the general at present technology that adopts is to use electric capacity to make compensating device, give the upper limit scaled values and the lower limit scaled values of first setting power factor, control system is lower than lower limit or is higher than higher limit according to the power factor of electrical network, correspondingly drops into or excision capacitor group.Because this technology is to control foundation by way of compensation with power factor value, when just having little load, total system vibrates easily, the low shortcoming of compensation precision when loading greatly.For the elimination of capacitance compensation system oscillation, Chinese patent CN85-100197 " a kind of power factor calibration system of eliminating the invalid throwing deactuate work of electric capacity " has done partly to solve.This known technology is to be provided with one " invalid action locking link " in compensation control circuit, when system when dropping into capacitor adjacent twice, if power factor value equates that control circuit promptly sends the input block signal.Electrical network has been avoided the invalid switching of electric capacity.And in operation of power networks, it is unequal twice input power factor value often to occur, but throw in-of oscillation takes place.At this moment, just do not eliminate the invalid switching of electric capacity.

Purpose of the present invention, aim to provide a kind of common unit that utilizes measured power factor angle in the electrical network, realization compensates electrical network according to reactive power value, prediction is also eliminated the invalid switching action of compensating device, carries out the power factor scaled values and carries out control method and the bucking-out system that self-adaptation is adjusted with respect to network load.

1., with electric capacity, inductance or its equivalent electrical circuit by way of compensation in the electrical network of device method proposed by the invention is:, at first utilize electrical network conventionally test device to obtain the live signal of line voltage, electric current, obtain electrical network at one group of forward and backward power-factor angle of compensating device action of switching through conversion.2., according to two power-factor angles before and after the action of one group of compensating device of resulting electrical network switching and power factor scaled values, use the operation control device of forming by numeral＜〉device, calculate the reactive power of electrical network.3., again according to reactive power and the power factor scaled values of calculating the gained electrical network, use the motion control device of forming by digital logic device, to electrical network once more the switching compensating device vibration can take place carries out the prediction judgement:

(a), when judging when can not vibrate, calculating according to the size of reactive power needs to drop into or the compensating device group number of excision, drops into or the compensating device of excision respective sets number.

(b), just take the power factor scaled values operation of floating when judging when will vibrate.Promptly according to network load, the power factor scaled values of switching action is done the self-adaptation adjustment, move down scaled values, the pairing power-factor angle zero line of scaled values is overlapped with the power-factor angle of electrical network at this moment.Response time afterwards is when arriving, if the power factor in the electrical network remains unchanged or its variation range less than upper limit scaled values during greater than the lower limit scaled values, compensating device is not made switching: when the variation of power factor of electric network greater than the upper limit scaled values after moving down, or during less than the lower limit scaled values after moving down, then restart the switching of one group of compensating device, repeat above signal transformation processing procedure.If be judged to vibration again, the power-factor angle zero line of scaled values continues to move, if be judged to nonoscillatory, scaled values power-factor angle zero line homing.

In finishing said process, simultaneously power-factor angle is carried out time sharing sampling, superposition and on average reach secondary weighted digital correlation such as average and handle, obtain the power factor value of electrical network through conversion, and carry out numeral demonstration.

Fig. 2 is for using the schematic block circuit diagram of above-mentioned " automatic compensation method of reactive power " custom-designed " reactive power automatic compensation system ", wherein (13) are the electrical network backbone, (10) be compensating device, (9) be the control performer, (11) survey link for the real-time power network voltage and current signal, (1) is the signal transformation link, (2) be the power factor scaled values, compensating device group number, the model selection link of switching response time, (3) be the s operation control link, (4) latch link for the output expansion, (5) drive link for output, (6) for isolating amplifying element, (7) drive link for latching decoding, (8) are cos φ value digital indicator, and (12) are control circuit, be connected in the acquisition of signal link (11) of electrical network backbone, provide line voltage, the live signal of electric current through signal transformation link (1), is transformed to the two-way square-wave signal with it.Simultaneously, transform part is transformed to ac voltage signal and current signal the power network current keying level signal that electrical network overvoltage protection keying level signal and bucking-out system start again.This four road signal is together given s operation control link (3), and it is poor that s operation control link (3) detects the forward position difference or the edge, back of voltage, current square-wave signal, promptly obtains the power-factor angle φ of electrical network.Model selection (2) is given fixed power factor scaled values, compensating device group number and switching response time and is also delivered to s operation control link (3) simultaneously, and s operation control link (3) is handled φ and above-mentioned input signal according to giving fixed operation processing program.After finishing various computing judgment processing, s operation control link (3) latchs the coded signal that link (4) is sent the compensating device switching to the output expansion, the output expansion is latched link (4) and is sent the switching control signal according to giving fixed compensating device switching mode (can be binary code, torsion circle sign indicating number, reflected code) to output driving link (5), again through isolating amplifying element (6) drive controlling performer (9), the switching or the excision of removing control compensation device (10).Simultaneously, s operation control link (3) calculates power factor value according to power-factor angle, and to the digitally encoded signal that latchs decoding driving link (7) output power factor value.Latching decoding drives link (7) and sends the digital displaying signal of cos φ value, cos φ digital indicator (8) demonstration power factor value to COS φ digital indicator (8).

Wherein, s operation control link (3) can be made up of various digital logic devices, can be microprocessor and memory under program, one chip microcomputer.Its internal arithmetic handling procedure comprises following Intelligent treatment link:

The time sharing sampling of a, power factor value, superposition on average reach secondary weighted digital correlation processing links such as average.

The calculating of b, power system reactive power, the prediction of throw in-of oscillation and processing repeatedly.

C, according to the size of network load, automatic power adjustment factor scaled values realizes the minimum reactive power operation of electrical network.

D, according to the model selection input state, select the switching response time automatically, switching action scaled values, switching compensating device group number are according to external cabling Scheme Choice output encoder mode.

E, self diagnosis whether working properly, and indicate in real time by display.

Output expansion is latched link (4) and can be made up of monolithic output expansion latch, and output drives link (5) to be made up of the multi-channel power drive array, through the isolation amplification, both can have the contact performer, also can be with contactless performer.

Decoding drives link (7) to the power factor display circuit and cos φ digital indicator (8) is formed by latching, and cos φ digital indicator (8) can be made up of the LED nixie display.S operation control link (3) is sent BCD-7 section coded signal to latching decoding driving link (7), latchs decoding and drives directly driving LED nixie display of link (7).

Signal transformation link (1) can hand over detector and two-way hysteresis comparator circuit to form by two-way zero.

Compensating device (10) can be the capacitor group, also can be capacitor and inductor device group or its equivalent electrical circuit and forms.

Control circuit of the present invention (12) also can be used as a kind of high-precision digital power efficiency meter and uses, and is used for the power factor value of detection of grid.Obtain the live signal of line voltage, electric current from the signal detecting device that is connected in the electrical network backbone, send into the input end of this power factor meter, power factor meter just numeral shows the power factor value of electrical network, and measuring accuracy can reach 0.2%-0.1%.

1, because the present invention has realized compensating according to the power system reactive power size, improved compensation precision.

2, because the present invention has vibration prediction and inhibition link, fundamentally eliminate the invalid switching action of compensating device, reduced voltage ripple of power network and electric current shoves, improved the stability of compensation, realize the reactive power compensation unmanned, improved the life-span of executive component.

3, owing to adopted time sharing sampling, superposition on average to wait digital correlation to handle, improved the measuring accuracy of power factor value, precision can reach 0.2%-0.1%, and has realized digital demonstration.

4, because the present invention has adopted the large scale integrated circuit device, feasible simple in structure than conventional art, debugging is made easily, and process repeatability is strong, produces in batches conveniently, and cost reduces.

5, adopt the present invention, each parameter is set up wide ranges and accurately.Wherein: the power factor scaled values 0.85-1.00 of switching action; The switching response time is from * 20ms-256s or longer time; Switching compensating device group number both available digital switch or bonding line is made the fourth gear flexible conversion respectively, and also available programs is carried out digital setting; Both the contact control actuating component can be had, also contactless executive component can be with; Be not only applicable to the following system of 0.5kv, applicable to the high-pressure system more than the number kv yet; Both can use capacitance compensation, also can use the capacitor and inductor compensation.

6, because the present invention has adopted self-diagnosis technology, can whether normal by the work of LED nixie display observing system at any time, the maintainer is brought great convenience.

7, adopt the present invention, when network load has bigger increase and decrease, can realize the disposable switching compensation of many groups, improve power network compensation stability.

8, because the present invention has adopted the self-adaptation adjustment of power factor scaled values with respect to network load, can make electrical network with minimum reactive power operation.

Description of drawings is as follows:

Fig. 1: the power factor scaled values of expression compensating device switching action is carried out the principle schematic that self-adaptation is adjusted with respect to network load.Wherein the P axle is represented electric network active power, the Q axle is represented power system reactive power, Qo is one group of reactive power that compensating device had, it is the upper limit scaled values and the pairing power-factor angle of lower limit scaled values of zero line that φ os and φ ox are respectively with the P axle, S is the applied power of electrical network, and φ s is the power-factor angle that S has.Cross the parallel lines that Qo makes Upper Bound Power factor angle lower sideline.Intersect at A with the upper sideline of lower limit power-factor angle, form the OQoA triangle.When S is positioned at the OQoA triangle, one group of compensating device of switching will cause repeatedly the switching action again, cause electrical network to shake, at this moment the pairing power-factor angle zero line of scaled values that just switching moved moves to the S axle, upper limit scaled values is COS(φ s-φ os), the lower limit scaled values is COS(φ s+ φ ox).And 〈 ﹠﹠〉in triangle OQoA the time, network load is more little, and φ s is big more; Network load is big more, and φ s is more little.

Fig. 2: see before and state.

Fig. 3: the system chart of expression one embodiment of the invention.A wherein, B, C is the three phase network backbone, HY is a voltage transformer (VT), HL is a current transformer, I, II, III, IV is four road building-out capacitors, the ratio of capacity is 8: 4: 2: 1,1J, 2J, 3J, 4J is a pilot relay, 1CJ-4CJ is an A.C. contactor, 139 is monolithic four voltage comparators, MCS-48 is an one chip microcomputer, the voltage transformer (VT) HY that is connected in electrical network AC phase detects the real-time voltage signal of electrical network, the current transformer HL that is connected in electrical network B phase detects the real-time current signal of electrical network, these two kinds of signals are admitted to 〈 ﹠﹠〉voltage comparator 139, be transformed to voltage respectively, the square-wave signal of electric current, the high-low level signal of the power network current that power network overvoltage signal and bucking-out system start, this four road signal is together sent into one chip microcomputer MCS-48.Simultaneously, finish model selection by six miniature code switchs, wherein represent the fourth gear switching response time for two, represent fourth gear opening-closing capacitor bank number for two, represent fourth gear power factor switching action scaled values for all the other two, give fixed mode select signal and also send into MCS-48, MCS-48 and carry out that s operation control is handled and logic determines is handled.After the processing, draw four coded signals of switching compensation condenser group number, output to four d flip-flop 4042 and latch, after the buffering of four tunnel in seven road drive arrays 1413, drive four relay 1J-4J.The normally opened contact of this No. four relay is controlled No. four contactor 1CJ-4CJ again, controls the switching or the excision of No. four capacitor groups.No. four capacitor groups are respectively according to 8: 4: 2: 1 numeric coding connects, and whole compensation condenser group number is 15 groups.In addition, the COS φ value that single-chip microcomputer MCS-48 calculates is again with the output of 10 position digital codings, and four charactrons that go to drive FR1424-14P through two two-way that latch in decoder driver 5411 and 1413 show.

Fig. 4 represents the signal transformation link schematic diagram of control circuit among the embodiment.Wherein (a) is the voltage square wave signal change-over circuit, (b) is the electric current square wave conversion circuit, (c) is electrical network overvoltage signal conversion circuit, (d) the power network current signal conversion circuit that starts for bucking-out system.

(a): the voltage square wave signal translation circuit is a core by a comparer in monolithic four voltage comparators 139, with resistance 1R1-1R7 and the common zero friendship detector of forming of diode D1, the voltage signal U of input AC phase _AC～, the output voltage square-wave signal.

(b): the current square-wave signal transducer is identical with composition (a), input B phase current signal I _b～, the output current square-wave signal.

(c): electrical network overvoltage signal conversion circuit is formed U by diode D3, potentiometer W1 and capacitor C 1, C2 _AC～current rectifying and wave filtering circuit.Resistance 1R15-1R18, potentiometer W1 and a voltage comparator of 139 are formed sluggish type voltage comparator circuit.(c) input U _AC～.When the line voltage amplitude in allowed band, (c) output high level; When the electrical network overvoltage, output low level.

(d) the circuit composition is similar to (c), input I _b～, output high level when electrical network normally moves; The output low level during operation of electrical network undercurrent.

Fig. 5 represents the output executing circuit schematic diagram of control circuit among the embodiment.Wherein 4042 is four d flip-flop, 1413 is 7 road drive arrays, control coded signal D1-D4 by four switchings that single-chip microcomputer MCS-48 comes, under the trigger action of gating pulse CL, latch its output signal Q1-Q4 four relay 1J-4J of four tunnel buffering rear drives in seven road drive arrays 1413 by four d flip-flop 4042.

Fig. 6 represents the COS φ digital display circuit schematic diagram of embodiment control circuit.Wherein (a) is the sign bit and the integer-bit display circuit of power factor value, (b), (c) be respectively the two-decimal position display circuit of power factor value.

(a) form by charactron DS, D among the two-way in seven road drive arrays 1413, resistance 4R1-4R4 and the ER1424-14P.By the next signal D of single-chip microcomputer MCS-48 _M, D _NBe the input signal of (a), wherein DM characterizes the sign bit of powerfactorcos value.When this position is 1, Ds shows L, and the expression network load be perceptual, is lagging power-factor; When DM was 0, Ds showed C, and the expression network load is a capacitive, is leading power factor.DN characterizes the integer-bit of power factor value, and when this position is 1, D shows 1, and this position is 0, demonstration 0.

(b) form by seven sections display latch decoder drivers 4511, resistance 4R5-4R11 and FR1424-14P charactron DI.Input signal DB0-DB3 is the coded signal of binary-coded decimal, first bit value behind the DI demonstration radix point.

(c) the circuit composition is identical with (b), second order digit value behind the D II demonstration radix point.

Embodiments of the invention:

The secondary coil of the voltage transformer (VT) HY summation current transformer HL of 3 li in accompanying drawing is received U in the accompanying drawing 4 _AC～, I _b～signal input part, at the HL secondary coil and connect one 0.4 Ω pull-up resistor, by (a) circuit of accompanying drawing 4 and (b) the two-way square wave output terminal of circuit be connected respectively to T1 and the 〈 ﹠﹠ of single-chip microcomputer MCS-48 hold, accompanying drawing 4(c) circuit and accompanying drawing 4-(d) output terminal of circuit is connected respectively to the I/O port of MCS-48, and 6 road mode selection switchs also link to each other with the I/O port of MCS-48 in addition.

Carry out the D1-D4 end that control signal is connected to accompanying drawing 5 from the tetrad coding of the I/O port of MCS-48 output, receive CL with the PROG signal of MCS-48 as 4042 control wave in the accompanying drawing 5 and hold.

10 COS φ value coded signals by the I/O port of single-chip microcomputer MCS-48 is exported are connected with input end DM, DN, the DBO-DB7 of accompanying drawing 6.

The normally open contact of four relays among Fig. 3 is received the coil of four contactors, and main contact one side of contactor is respectively by 8: 4: 2: 1 coding is connected with No. four capacitor groups, and opposite side then joins with the electrical network backbone.

As mentioned above, control circuit is connected with backbone finishes, and debugged all operation processing programs according to Intelligent treatment link proposed by the invention, its code is solidified among the EPROM of single-chip microcomputer MCS-48, total system can put into operation.

Claims (13)

1, the automatic control method that detects and compensate of a kind of power system reactive power.Be used for electric capacity, inductance or its equivalent electrical circuit is the reactive power compensation system of compensating device, record the live signal of line voltage, electric current earlier, handle through signal transformation, finally remove the switching of control compensation device, it is characterized in that the signal transformation processing procedure is as follows to control performer output control signal:

(1) at first utilizes electrical network conventionally test device to obtain voltage, the current signal of electrical network, obtain electrical network at one group of forward and backward power-factor angle of compensating device of switching through conversion.

(2) secondly according to resulting electrical network in one group of compensating device action of switching forward and backward two power-factor angles and power factor scaled values, The operation control device that use is made up of digital logic device, calculate the reactive power of electrical network.

(3) again according to the reactive power and the power factor scaled values that calculate, The operation control device that use is made up of digital logic device, to electrical network once more the switching compensating device vibration can take place carries out prediction and judge:

(a) when judgement can not vibrated, then the size according to reactive power calculates the compensating device group number that needs to drop into excision, drops into or excise the compensating device of respective sets number.

(b) when judgement will be vibrated, just adopt the operation of floating power factor scaled values, promptly move down scaled values, its corresponding power-factor angle zero line is overlapped with the power-factor angle of electrical network at that time, when the response time arrives afterwards, the power factor of electrical network constant or its when changing within the bound scope of the scaled values after moving down, compensating device is not done the switching action.If the power factor of electrical network, then begins the switching action of one group of new compensating device again greater than the upper limit scaled values after moving down or less than the lower limit scaled values after moving down, repeat above signal transformation processing procedure again.

2, method according to claim 1 is characterized in that said operation control device is to be that core is formed with the computing machine in (2) and (3).

3; a power system reactive power self compensating system; comprise electrical network backbone (13); compensating device group (10); control performer (9); acquisition of signal link (11) and control circuit (12); it is characterized in that control circuit (12) includes signal transformation link (1); model selection link (2); s operation control link (3); link (4) is latched in the output expansion; output drives link (5); isolate amplifying element (6); latch decoding and drive link (7); cos φ digital indicator (8); control procedure is as follows: the real-time voltage that acquisition of signal link (11) is detected; current signal; send into signal transformation link (1); signal transformation link (1) provides voltage to s operation control link (3); current square-wave signal; the electric current keying level signal that the level signal of electrical network overvoltage protection action and bucking-out system start; s operation control link (3) is according to model selection (2) the fixed power factor scaled values of giving; compensating device group number and switching response time; input signal is carried out digital processing; latch the coded signal that link (4) is sent control compensation device switching to the output expansion; coded signal drives link (5) through output and removes to isolate amplifying element (6); isolate amplifying element (6) and drive control performer (9); carry out the switching control of external compensating device (10); simultaneously; s operation control link (3) is to the digitally encoded signal that latchs decoding driving link (7) output power factor value; latch decoding driving link (7) and send digital displaying signal to cos φ digital indicator (8), cos φ digital indicator (8) is made numeral and is shown.

4, system according to claim 3 is characterized in that said s operation control link (3) is is that core devices is formed with the one chip microcomputer.

5, according to claim 3 and 4 described systems, it is characterized in that cos φ digital indicator (8) is made up of the LED nixie display, latch decoding and drive the BCD-7 piece of digital coded signal that link (7) input is sent from s operation control link (3), export 7 sections shows signal to cos φ digital indicator (8).

6,, it is characterized in that signal transformation link (1) hands over detector and two-way hysteresis comparator circuit to form by two-way zero according to claim 3 and 4 described systems.

7, system according to claim 5 is characterized in that signal transformation link (1) hands over detector and two-way hysteresis comparator circuit to form by two-way zero.

8, according to claim 3 and 4 described systems, it is characterized in that said output expansion latchs link (4) and is made up of monolithic output expansion latch, output driving link (5) is made up of multi-channel power drive array device.

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