A kind of control circuit of low-voltage reactive compensator capable and control method thereof
Technical field
The present invention relates to the electric network reactive compensation field, be specifically related to a kind of control circuit and control method thereof of low-voltage reactive compensator capable.
Background technology
In commercial production and daily life, most of loads all are resistance sense property, need to consume a large amount of reactive powers.The transmission of reactive power in transmission line can cause electric current increase in the circuit, thereby increase the loss in the circuit.Also can cause simultaneously the decline of quality of voltage, power consumption equipment is caused adverse effect.Therefore, the application of reactive power compensator has important function for the power factor and the transmission voltage quality that improve system, helps efficient, the safe operation of electrical network, and is also significant for energy-saving and emission-reduction.
At present common reactive power compensator mainly is divided into two kinds of power factor type idle compensating control and reactive power type idle compensating controls according to the difference of sampling physical quantity.Since electric power system general direct with power factor as the whether qualified detection index of user power utilization, the power factor type controller that with the power factor is controlled quentity controlled variable be the most simply, the most traditional controlling schemes.But in the practical application, when underloading, be prone to " switching concussion " phenomenon of frequent switching; Satisfy condition though power factor when heavy duty, can occur, the still very big situation of idle component of load can not accomplish the tracking of reactive power is regulated conscientiously.The deficiency of power factor type controller that has been the then comparatively perfect solution of the controller of controlled quentity controlled variable with the reactive power can perform to the effect of compensation arrangement best.Existing low-voltage reactive compensator capable have small product size big, inner complicated, maintainable poor, use inflexible shortcoming.
Summary of the invention
To the deficiency of prior art, the present invention provides a kind of low-voltage reactive compensator capable and control method thereof, has overcome the shortcoming and the frequent switching problem that has easy appearance in the nine district figure control now of existing low-voltage reactive compensator capable.
The control circuit of a kind of low-voltage reactive compensator capable provided by the invention, said reactive power compensator comprises capacitor; Its improvements are that said control circuit comprises control module, power module, human-computer interaction module, acquisition module, data memory module, communication module, switching control circuit, operating passing zero module and protection alarm module; Said control module is connected with said power module, said human-computer interaction module, said acquisition module, said data memory module, said communication module, said switching control circuit and said protection alarm module respectively; Said switching control circuit is connected with said capacitor with said operating passing zero module successively.
Wherein, said reactive power compensator is that three-phase is mended mode altogether, and then said sampling module is taked the line voltage U of A, C phase
AC, get the phase current I of B phase
BSaid capacitor comprises that two groups of Δ shapes connect the capacitor of method.
Wherein, said reactive power compensator is a three-phase branch benefit mode, and then said sample circuit is taked the phase voltage U of A, B, C three-phase
A, phase voltage U
BWith phase voltage U
C, get the phase current I of A, B, C three-phase
A, phase current I
BWith phase current I
CSaid capacitor comprises the capacitor of a star connection.
Wherein, when at least two said reactive power compensator constitutes the three-phase mode of mending altogether and combines with three-phase branch benefit mode, parallel connection formation three-phase mixing compensation system between said reactive power compensator.
Wherein, the switch of switched capacitor is selected the combination switch with no-voltage conducting and zero current break function for use, to reduce the surge current in capacitor input and when excision.
Wherein, said control module comprises the LPC2388 controller.
Wherein, said human-computer interaction module comprises keyboard and LCD display; Said keyboard is used to be provided with the parameter of reactive power compensator, and said LCD display is used to show power factor, voltage, electric current, active power and the reactive power parameter of three-phase.
Wherein, said communication module adopts the RS485 communication mode, and it selects to insert said reactive power compensator quantity and type according to load, and selected one of them be main frame, work by the mode of master-slave communication with remaining device.
The present invention is based on a kind of control method that another purpose provides based on low-voltage reactive compensator capable; Its improvements are; Improve according to magnitude of voltage and reactive power value Jiang Jiu district figure, said LPC2388 controller carries out Region control according to improved nine district figure, and control command is passed to said switching control circuit and said operating passing zero module; The capacitor of the said reactive power compensator of switching carries out real-time reactive power compensation to said network system.
Wherein, said improved nine district figure divide according to magnitude of voltage and reactive power value, wherein:
Upper voltage limit value U
OnWith lower voltage limit value U
DownNetwork system is divided into three parts; Greater than said upper voltage limit value U
OnThe zone be 1 district; Less than said lower voltage limit value U
DownThe zone be 6 districts;
Said upper voltage limit value U
OnConstituting anti-concussion zone with magnitude of voltage 1, is 2 districts, said lower voltage limit value U
DownConstituting anti-concussion zone with magnitude of voltage 2, is 5 districts; Magnitude of voltage 1 is said upper voltage limit value U
On-6, magnitude of voltage 2 is said lower voltage limit value U
Down+ 6;
Being divided into three parts according to the reactive power Q value between said magnitude of voltage 1 and the said magnitude of voltage 2, is 4 districts less than the zone of said reactive power Q value lower limit, is 3 districts greater than the zone of the said reactive power Q value upper limit, wherein between the zone be 0 district.
Wherein, the control method of zones of different comprises among the said improved nine district figure:
0 district: do not carry out reactive power compensation;
1 district: capacitor is excised one by one, till complete resection;
2 districts: if the capacitance that calculates required excision then excises capacitor greater than the condenser capacity that drops into;
3 districts: drop into capacitor;
4 districts: excision capacitor;
5 districts: if the capacitance of the required input of calculating is greater than the condenser capacity that does not drop into, then with the capacitor input;
6 districts: capacitor is dropped into one by one, till whole inputs.
Wherein, said LPC2388 controller record capacitor switching number of times and switching time; In the switching process, the according to value switching of different capabilities capacitor, with little the throwing earlier of switching frequency of capacity capacitor, what switching frequency was big cuts earlier, equal switching frequency, switching big throwing earlier blanking time reaches maximum with life-span and the utilance that guarantees electric capacity.
Wherein, according to the number of the said reactive power compensator of network system capacity setting; If said reactive power compensator greater than one group, carries out the master and slave devices setting.
Wherein, need the parameter determining of the reactive power of compensation, occupy the ratio value of merit power for power factor and the maximum reactive power that allows by two settings.
Wherein, At least two said reactive power compensator formation three-phase mends mode altogether and three-phase branch benefit mode combines; The main frame of said reactive power compensator is common benefit mode; Divide the said reactive power compensator slave of mending to obtain voltage, telemetering of current information in real time from other, carry out logic determines for main frame.
Wherein, during system works, main frame sends querying command to each slave in real time, and slave comprises to the information that main frame returns: the working method of each slave (three-phase mend altogether or divide benefit), capacitor volume, switching state, switching time; Main frame also timing is ordered when each slave sends school, and is synchronous with the time maintenance that guarantees main frame and each slave, realizes with the form of sending broadcasting command during the school; When main frame needs slave to carry out switching when action of capacitor through the logical program judgement, can send the switching order to this slave; If system is the mixed compensation mode, and main frame is common benefit mode, and then main frame is operated in the slave transmission inquiry telemetry intelligence (TELINT) order that branch is mended mode to certain in real time.
With the prior art ratio, beneficial effect of the present invention is:
(1) adopts improved nine districts figure control strategy, overcome the frequent switching problem that occurs easily in traditional nine district figure control.
(2) realize the setting of parameter through panel and keypad, and utilize LCD to show, simple and clear human-computer dialogue, simple to operate.
(3) have over-voltage protection function, safe in utilization.
(4) can realize the no-voltage conducting and the zero current break function of capacitor, have low in energy consumption, the advantage such as little of shoving of operation.
(5) communication module in the device can realize many table apparatus group net operation easily.
(6) have low, the applying flexible of cost, and can realize the advantage of quick, the accurate switching of capacitor.
(7) there is the situation of pressure regulation repeatedly and capacitor switching in existing nine district's figure control strategies.For example when system was in 1 district, voltage was got over the upper limit, and the idle upper limit more needs first step-down, makes voltage normal, thereby gets into 2 districts.But after dropping into capacitor, idle normal, voltage can raise simultaneously, might get into 8 districts, needs step-down again, thereby has caused the frequent adjusting of load tap changer and the switching repeatedly of capacitor.The present invention is used for the low-voltage customer side, and voltage regulating device is not set, and is employed in the improvement nine district figure control strategies that anti-concussion zone is set on idle-voltage plane, can avoid the frequent switching of capacitor effectively.
Description of drawings
Fig. 1 is the system construction drawing of low-voltage reactive compensator capable provided by the invention.
Fig. 2 is the sketch map of improved nine districts figure provided by the invention.
Fig. 3 is the flow chart of main-machine communication process provided by the invention.
Fig. 4 is the flow chart of slave communication process provided by the invention.
Embodiment
Do further to specify below in conjunction with the accompanying drawing specific embodiments of the invention.
Present embodiment proposes a kind of low-voltage reactive compensator capable of intelligence; Constitute by control circuit and capacitor; Consider the detection index of electric power system and direct controlled quentity controlled variable different, the present invention considers voltage, power factor and reactive power simultaneously, as the foundation of control capacitance device switching.
The control circuit of a kind of low-voltage reactive compensator capable that present embodiment provides, reactive power compensator comprises capacitor, and working method is that three-phase divides in the device of mending, and capacitor is a star connection; Working method is that capacitor connects method for Δ shape in the device mended altogether of three-phase.Its control section is as shown in Figure 1, comprises control module, power module, human-computer interaction module, acquisition module, data memory module, communication module, switching control circuit, operating passing zero module and protection alarm module; Said control module is connected with said power module, said human-computer interaction module, said acquisition module, said data memory module, said communication module, said switching control circuit and said protection alarm module respectively; Said switching control circuit is connected with capacitor with said operating passing zero module successively.Power module is the control circuit power supply.The data that the data memory module real-time storage is gathered.Indication (indication of led lamp) is protected and alarmed to the protection alarm module when three-phase imbalance, the phase failure, overcurrent, excess temperature.Capacitor is at overvoltage, mistake harmonic wave, out of service when ambient temperature is too high.
When said reactive power compensator is that three-phase is mended mode altogether, then said sampling module is taked the line voltage U of A, C phase
AC, get the phase current I of B phase
BSaid capacitor comprises that two groups of Δ shapes connect the capacitor of method.When said reactive power compensator is a three-phase branch benefit mode, then said sample circuit is taked the phase voltage U of A, B, C three-phase
A, phase voltage U
BWith phase voltage U
C, get the phase current I of A, B, C three-phase
A, phase current I
BWith phase current I
CSaid capacitor comprises the capacitor of a star connection.When at least two said reactive power compensator constitutes the three-phase mode of mending altogether and combines with three-phase branch benefit mode, parallel connection formation three-phase mixing compensation system between said reactive power compensator.
The human-computer interaction module of present embodiment comprises keyboard and LCD display; Keyboard comprises four buttons, can realize the input that is provided with of each parameter.Be provided with under the state non-, LCD can show parameters such as the power factor, voltage, electric current, active power, reactive power of each phase in turn.
The said control module of present embodiment comprises the LPC2388 controller.
According to said apparatus; A kind of control method based on low-voltage reactive compensator capable that present embodiment provides is; Improve according to magnitude of voltage and reactive power value Jiang Jiu district figure, said LPC2388 controller carries out Region control according to improved nine district figure, and control command is passed to said switching control circuit and said operating passing zero module; The capacitor of the said reactive power compensator of switching carries out real-time reactive power compensation to said network system.
Wherein improved nine district figure divide according to magnitude of voltage and reactive power value, and it is as shown in Figure 2 to divide figure, the concrete division as follows: upper voltage limit value U
OnWith lower voltage limit value U
DownNetwork system is divided into three parts; Greater than said upper voltage limit value U
OnThe zone be 1 district; Less than said lower voltage limit value U
DownThe zone be 6 districts.Said upper voltage limit value U
OnConstituting anti-concussion zone with magnitude of voltage 1, is 2 districts, said lower voltage limit value U
DownConstituting anti-concussion zone with magnitude of voltage 2, is 5 districts; Magnitude of voltage 1 is said upper voltage limit value U
On-6, magnitude of voltage 2 is said lower voltage limit value U
Down+ 6.Being divided into three parts according to the reactive power Q value between said magnitude of voltage 1 and the said magnitude of voltage 2, is 4 districts less than the zone of said reactive power Q value lower limit, is 3 districts greater than the zone of the said reactive power Q value upper limit, wherein between the zone be 0 district.
Corresponding, the control method of zones of different comprises among the improved nine district figure:
0 district: do not carry out reactive power compensation;
1 district: capacitor is excised one by one, till complete resection;
2 districts: if the capacitance that calculates required excision then excises capacitor greater than the condenser capacity that drops into;
3 districts: drop into capacitor;
4 districts: excision capacitor;
5 districts: if the capacitance of the required input of calculating is greater than the condenser capacity that does not drop into, then with the capacitor input;
6 districts: capacitor is dropped into one by one, till whole inputs.
Wherein, reactive power is by the parameter determining of two settings: according to the actual loading situation, the ratio value that target power factor and the maximum reactive power that allows are occupied merit power is set by the user.Performance assessment criteria with electric power system---power factor is primary parameter, calculates the reactive capability that will reach required input of target power factor or excision, and carries out the switching of capacitor.When power factor satisfies condition; Calculate reactive power again and whether satisfy condition, if do not satisfy condition, the reactive capability that drops into or excise as required; Proceed the switching of capacitor, overcome that power factor satisfies condition but the still very big drawback of reactive power.Because both are to be controlled quentity controlled variable with the reactive power after all, have also avoided the generation of " switching concussion " situation.
The LPC2388 controller record capacitor switching number of times and the switching time of present embodiment; In the switching process, the according to value switching of different capabilities capacitor, with little the throwing earlier of switching frequency of capacity capacitor, what switching frequency was big cuts earlier, equal switching frequency, switching big throwing earlier blanking time reaches maximum with life-span and the utilance that guarantees electric capacity.
Transmit information and order when the communication module in the device is used for many table apparatus on-line working, the user can setting device be main frame or slave on panel.The quantity of the reactive power compensator of selecting according to different power system capacity to insert, the largest device number that system allows to insert is 32.When system works, slave no longer carries out logic determines, but the switching of switching order the carrying out capacitor that the reception main frame sends.
If system is the mixed compensation mode, and main frame is common benefit mode, and need divide the slave of mending to obtain telemetry intelligence (TELINT)s such as voltage, electric current in real time this moment from other, carries out logic determines for main frame.
During system works, main frame sends querying command to each slave in real time, and slave comprises to the information that main frame returns: the working method of each slave (three-phase mend altogether or divide benefit), capacitor volume, switching state, switching time; Main frame also timing is ordered when each slave sends school, and is synchronous with the time maintenance that guarantees main frame and each slave, realizes with the form of sending broadcasting command during the school; When main frame needs slave to carry out switching when action of capacitor through the logical program judgement, can send the switching order to this slave; If system is the mixed compensation mode, and main frame is common benefit mode, and then main frame is operated in the slave transmission inquiry telemetry intelligence (TELINT) order that branch is mended mode to certain in real time.The flow chart of main frame, slave communication process is respectively like Fig. 3, shown in Figure 4.
As shown in Figure 3, the main-machine communication process comprises the steps:
(1) system initialization;
(2) the LPC2388 controller judges that main frame is whether idle, if the free time is then carried out step (3), otherwise controller sends data, and host receiving data is also handled;
Order when (3) main frame judges whether need to send the school,, otherwise carry out step (4) if order when needing then to send the school as slave;
(4) main frame judges whether to need to send the switching order, if need then to send the switching order as slave, otherwise carries out step (5);
(5) main frame need to judge whether the inquiry telemetry intelligence (TELINT), if need then slave to be sent the order of inquiry telemetry intelligence (TELINT), otherwise carries out step (6);
(6) main frame need to judge whether inquiry from machine information, if need then slave to be sent inquiry slave message command, if do not need then to finish.Slave information comprises the working method (divide to mend still and mend altogether) of slave, slave capacitor volume, switching state, switching time, switching frequency.
As shown in Figure 4, the slave communication process comprises: the initialization of elder generation of system, begin thereafter to accept host data and handle, and wherein, the order of sending during according to main-machine communication (like step (3)-(6)) is sent corresponding information result and is given main frame.
The switch of switched capacitor is selected the combination switch with no-voltage conducting and zero current break function for use, to reduce the surge current in capacitor input and when excision.In addition, system has at alarm and the automatic defencive function out of service crossed under the situation such as harmonic wave, overcurrent, overvoltage, excess temperature.
The communication module of present embodiment adopts the RS485 communication mode, and it selects access device quantity according to load, selects one of them and is main frame, and the residue device is a slave, makes between each device to work by the mode of master-slave communication.
The present invention is in the reactive power compensation experiment, and experimental data is (the target power factor is made as 0.95 in the experiment, and the ratio that the maximum reactive power that allows is occupied merit power is 20%) shown in table 1, table 2.
Table 1 three-phase divides benefit mode experimental result
Table 2 three-phase is mended the mode experimental result altogether
Experimental result shows that the present invention can realize the accurate switching of capacitor, reaches the purpose that improves power factor.
Should be noted that at last: above embodiment is only in order to technical scheme of the present invention to be described but not to its restriction; Although the present invention has been carried out detailed explanation with reference to the foregoing description; Under the those of ordinary skill in field be to be understood that: still can specific embodiments of the invention make amendment or be equal to replacement; And do not break away from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present invention.