Background technology
Capacitance reactive compensation is that the various electrical loads of power network are used for regulation voltage and improve the most general modal compensation arrangement of power factor (PF), also is the reactive power source that electric power system generally adopts.But the present domestic mechanical type circuit breaker opening-closing capacitor bank (MSC) that almost all adopts, there are the following problems for it.When circuit breaker dropped into, impulse current was big, not only influences electrical network, and increased the contact of breaker electrical wear, did not allow frequent operation, can only adapt to the load of slow variation.If voltage ripple of power network is big, the vibration frequency height, particularly Railway Electric traction, arc furnace, rolling mill, oil-field oil pumper, the big capacity elevator of mine etc. often big load jumpy are carried out pressure regulation and reactive power compensation with mechanical type circuit breaker opening-closing capacitor bank, are difficult to be competent at.Mechanical type circuit breaker opening-closing capacitor bank only is applicable to the static voltage adjustment and the reactive power compensation of slow variation.
After power electronic technology occurs, the beginning development and Application following dynamic reactive compensation device, as thyristor operating passing zero capacitor group (TSC), thyristor-controlled reactor (TCR)+capacitor group (MSC) is based on the SVG of unsteady flow principle.This class reactive-load compensation equipment, have non-impact current, reaction speed fast, advantage, the higher or quick dynamic adjustments of voltage reactive voltage jumpy of applicable vibration frequency such as can frequently regulate.But this kind equipment investment is high, and power consumer is difficult to accept.And allow operating voltage low, when inserting high voltage bus, have to install additional intermediate transformer, more increase project cost.
A kind of thyristor series voltage-regulating capacitance reactive compensation device is arranged, be called for short russian CKY, use within the specific limits, it is low than the TSC cost, but still has shortcomings such as cost height, control technology complexity.The principle of this device is a tapping that changes auxiliary transformer by thyristor switching equipment, change the connection set of auxiliary transformer simultaneously, thereby change the additional electromotive force that the TB secondary winding is produced, and then change the size of capacitor group C both end voltage, control capacittance is idle.Because the change of the additional electromotive force of auxiliary transformer secondary winding is to realize by the thyristor switching equipment of a winding of auxiliary transformer, so be called indirect variable pressure type capacitance reactive compensation device.This device needs two transformers, though total capacity only is 60% of a compensation arrangement rated capacity, has still increased installation cost.In addition, the thyristor switching equipment of russian CKY has different tie lines in changing grade process, causes flowing through the thyristor switch electric current not at the same level, and its direction changes, and causes the complexity of changing level control, thereby has hindered applying of russian CKY.
Summary of the invention
The objective of the invention is to: method and equipment therefor that a kind of new control capacittance reactive power is provided.The present invention only uses an auxiliary transformer; Thyristor switching equipment is connected on the auxiliary transformer secondary side, directly changes capacitor voltage at both ends; Thyristor switching equipment only changes the auxiliary transformer secondary winding equivalence number of turn, and the auxiliary transformer connection set remains unchanged before and after changing level.Installation cost reduces greatly, controls also very simply, and technical performance is still the same with TSC.
Implementation of the present invention is: the method for control capacittance reactive power is characterized in that: after compensation capacitors C and auxiliary transformer TB secondary windings in series or equivalent series, be connected to the same bus of electrical network jointly with winding of auxiliary transformer TB; Make line voltage put on capacitor group C on the one hand, the additional electromotive force that auxiliary transformer TB secondary winding is produced puts on capacitor group C in the other direction; Capacitor group C both end voltage is the mould of the difference of line voltage and additional electromotive force; Utilize thyristor switching equipment VT2 to change the tap number of turn or the equivalent number of turn of auxiliary transformer TB secondary winding, compare K to change TB first and second umber of turn, change the size of the additional electromotive force that secondary winding produced, and then change the size of capacitor group C both end voltage and the size of the reactive power that capacitor group C is sent.At capacitor group reactance X
CUnder the constant situation, the reactive power that the regulating capacitor group is sent.
In the method for above-mentioned control capacittance reactive power, also can utilize thyristor switching equipment VT1 to change the tap number of turn or the equivalent number of turn of a winding of auxiliary transformer, help out, cooperate the turn ratio that changes auxiliary transformer first and second winding.
The device that control capacittance reactive power method is used, it comprises the conventional capacitor group C and the current-limiting inductance L of serial connection; It is characterized in that: also comprise a three-phase auxiliary transformer TB and thyristor switching equipment VT2; The winding of three-phase auxiliary transformer TB directly and bus join, secondary winding is connected to the same bus of electrical network with after capacitor group C, current-limiting inductance L are connected in series; Thyristor switching equipment VT2 adopts " tap " or " bridge joint " mode to be connected to secondary winding, the tap number of turn of control break secondary winding or the equivalent number of turn.
In the device of above-mentioned control capacittance reactive power, the winding of three-phase auxiliary transformer TB can have the tap number of turn of the winding of control break that employing " tap " or " bridge joint " mode insert or the thyristor switching equipment VT1 of the equivalent number of turn.
Compared with the prior art.The present invention does not use intermediate transformer or power transformer, has only used an auxiliary transformer; Thyristor switching equipment is not connected in the major loop, neither be connected on the primary side of auxiliary transformer, but is connected on the auxiliary transformer secondary side, directly the control break capacitor voltage at both ends; Thyristor switching equipment only changes the auxiliary transformer secondary winding equivalence number of turn, and the auxiliary transformer connection set remains unchanged before and after changing level.Make installation cost and application cost reduce greatly, control also very simply that technical performance is still the same with russian CKY with TSC.Because thyristor switching equipment directly is connected on the auxiliary transformer secondary side, directly change is added in the terminal voltage at capacitor C two ends, so be called direct pressure swing type capacitance reactive compensation, is called novel transistor controlling series pressure regulation capacitance reactive compensation again.The present invention is used for capacitance reactive compensation, and it is low to have cost, and application cost is low, and simple, the easily realization of control allows the operating voltage height, the characteristics of control progression many (can reach more than 80 grades).According to China's present thyristor serial connection technology level, can directly meet sub-35KV, 110KV even 220KV.It can be widely used in each step voltage transformer station capacitance reactive compensation pressure regulation of electric power system, improve the high-tension line ability to transmit electricity; Also be specially adapted to the reactive power compensation of the higher various impact load power supplies of Railway Electric traction net, smelting and steel rolling equipment power supply buses and supply power voltage.
Embodiment
Embodiment: as shown in Figure 5, control capacittance reactive power method of the present invention be with ordinary capacitor group C with after current-limiting inductance L is connected routinely, by thyristor switching equipment VT2 be connected to the same bus of electrical network through circuit breaker Q F together with the winding of auxiliary transformer TB (can through or without thyristor switching equipment VT1) again after auxiliary transformer TB secondary winding is connected.Circuit breaker Q F only makes whole device input, excision (comprising failure removal) is used.Change the auxiliary transformer first and second tapping number of turn or the equivalent number of turn with thyristor switching equipment, promptly change the turn ratio K of auxiliary transformer first and second winding, when winding of auxiliary transformer applies line voltage when constant, the additional electrical that secondary winding produced will definitely take place to change on a large scale, add under the electromotive force acting in conjunction at line voltage U and the variable secondary winding of auxiliary transformer, capacitor group C both end voltage will take place to change on a large scale, thus capacitor group C sends idle will be adjustable on a large scale.Thyristor switching equipment is made up of a plurality of thyristor switchs.Each thyristor switch can be made of half control device triode thyristor or bidirectional thyristor, also can be made of full control device.Each thyristor switching equipment can directly connect different taps and change auxiliary transformer first and second umber of turn, and promptly " tap " formula connects; Also available thyristor switch constitutes bridge connection to the regulating winding of first and second winding, to regulating winding just connect, reversal connection or do not fetch the equivalent number of turn that changes winding, promptly " bridge joint " formula connects.The thyristor switching equipment that the change of first and second umber of turn is adopted is that " tap " connects or " bridge joint " do not fixed, and choose as required, and the number of turn of a winding can not regulated yet.
Shown in Figure 1 is the key wiring diagram of thyristor operating passing zero capacitor group (being TSC).It can directly insert 10KV and with Down Highway, insert 35KV and above bus, could insert after an intermediate transformer step-down.In the TSC mode, thyristor operating voltage height is 2 times of network rated voltage U
N, be the deadly defect that causes the TSC cost high.
Shown in Figure 2 is the key wiring diagram of TCR+MSC reactive power compensator.So-called TCR is exactly a thyristor-controlled reactor, and it is the change that comes implement device first-harmonic inductive current by the angle of flow that changes thyristor.So-called MSC comes opening-closing capacitor bank with mechanical switch exactly.Though the cost of TCR itself is lower than TSC, because of it can only regulate inductance current, and high order harmonic component is arranged, must could realize the adjusting of capacitive reactive power with capacitor group C parallel connection.Be mainly used in the place that 500KV transformer station perception is idle and capacitive reactive power is regulated.If be used for the place that 220KV and following transformer station only need capacitive reactive power, perhaps be used to improve ability to transmit electricity, with the cost of the unit capacity of TCR+MSC just than TSC height, but owing to technical reason, in smelting iron and steel and rolling large enterprise, China has adopted the TCR+MSC device more.Maximum operating voltage only is 35KV at present.
Shown in Figure 3 is the SVG mode key wiring diagram of static reacance power supply, and it is based on the inverter principle, can inhale and can send out idle, but the cost height, every megavar is greater than 500,000, and domestic have only a 20MVAR to come into operation.
Shown in Figure 4 is the key wiring diagram of russian CKY device, and it also is based on thyristor series voltage-regulating principle, in the existing practical application of Russia, lower than TSC cost.But required transformer capacity is still bigger, and thyristor control is complicated.Can only be connected to 10KV~35KV.
Shown in Figure 5 is the single-phase key wiring diagram of apparatus of the present invention.It still is based on thyristor series voltage-regulating principle and the remarkable difference of russian CKY is: 1) cancelled power transformer TY; 2) thyristor switching equipment VT2 and capacitor group C are placed on auxiliary transformer TB secondary winding side together and play main regulating action, and one time winding side thyristor switching equipment VT1 plays the fit adjustment effect, generally can; 3) thyristor switching equipment only changes auxiliary transformer first and second winding no-load voltage ratio, does not change connection set.The maximum characteristics of apparatus of the present invention are: required thyristor, transformer capacity are little, and the thyristor operating voltage is low, control is uncomplicated, and cost is low, can directly be connected to 35KV, 110KV and 220KV high voltage bus, and comprehensive cost is lower.
Shown in Figure 6 is " tap " formula thyristor switching equipment one joins line chart, 1~6 expression thyristor switch number, every grade is had only a thyristor switch to connect, capacitor is connected to a tap of auxiliary transformer TB first and second winding, thyristor switching equipment VT2 plays main regulating action, and VT1 cooperates (also shouldn't).
Shown in Figure 7 is " bridge joint " formula thyristor switching equipment one joins line chart, the secondary winding of auxiliary transformer TB is made of 3 coils, wherein the coil of W21, W22 sign is a regulating winding, constitute bridge connection with thyristor switch 1~4,5~8 with power supply respectively, the thyristor switch of each " bridge joint " can be realized just the connecing of regulating winding, reversal connection by the combination of orderly break-make or not connect, realize the change of the auxiliary transformer TB secondary winding equivalence number of turn.In like manner, winding of TB can be made of two coils, and the coil that W11 characterizes is a regulating winding, by the break-make combination of bridge joint thyristor switch 9~12, can realize just the connecing of regulating winding W11 and coil W12, reversal connection or not connect three kinds of working methods; Also available tapped thyristor switching equipment replaces; Also can umber of turn of not control break TB.
Shown in Figure 8 is that a kind of concrete wiring that the present invention's " tap " formula thyristor switching equipment is controlled is given an example.The thyristor switch 1~12 of thyristor switching equipment VT is that " tap " formula connects, and is connected in the alternate tap of TB secondary winding, and every level work state has only thyristor switch at the same level to connect all the other disconnections.F is a piezo-resistance among the figure, makes overvoltage protection usefulness, and L is the three-phase current-limiting reactor.
Shown in Figure 9 is that a kind of concrete wiring that the present invention's " bridge joint " formula thyristor switching equipment is controlled is given an example.Thyristor switching equipment VT2 is that " bridge joint " formula connects, the VT1 cancellation.TB first and second winding coupling is Y
0/ Y
0-12, this wiring can directly insert 110KV and 220KV bus.The power supply of TB first and second side all is connected to same bus.
Shown in Figure 10 also is that a kind of concrete wiring that the present invention's " bridge joint " formula is controlled is given an example.VT2 and VT1 are " bridge joint " formula thyristor switching equipment.Auxiliary transformer TB first and second winding adopts Δ/Δ-12 to connect.F
1, F
2, F
3Be over-voltage protection element.This wiring can directly insert 10KV~35KV bus.
Fig. 8~Figure 10 has represented the typical several physical cablings of the present invention, but be not limited solely to these 3 kinds, usually the physical cabling feature is: thyristor switching equipment VT1 and VT2 can adopt " bridge joint " or " tap ", also can adopt the combination of " bridge joint " and " tap ", and VT1 also shouldn't; Auxiliary transformer TB first and second winding also can adopt Y/d-11 or Y/d-1 equijoin mode except that adopting Y/Y-12 and Δ/Δ-12; Which kind of bind mode no matter, TB secondary side can equivalence be electrical network bus-L, C-VT2 and the TB secondary winding form that is in series, and winding of VT1 and TB is connected to the same bus of electrical network.After connection form design in a single day is definite, constant in the control of adjusting a wage scale.
Thyristor switching equipment of the present invention only changes auxiliary transformer first and second umber of turn ratio, does not change their connection set.Auxiliary transformer first and second winding coupling group can adopt Y/Y-12, Δ/Δ-12, Y/d-11, Y/d-1 or other connection form as required.
Three-phase auxiliary transformer involved in the present invention, its iron core and design of Windings and common transformer do not have essential distinction.
The present invention generally is used for electrical network, and the symmetrical capacitive reactive powers compensation of load three also can cooperate with inductance and be used for the three-phase asymmetry compensation, also can be used for single-phase, two-phase capacitive compensation, and method therefor, principle, every phase structure are constant substantially.Regulate though the present invention also is classification, " bridge joint " mode of employing changes the winding equivalence number of turn, can utilize the combination of different number of turn regulating windings, can realize the multistage adjusting more than 80 grades for two groups.