CN203504190U - Reactive power compensation device for partial voltage regulation and capacity regulation of three-phase four-wire power grid - Google Patents

Abstract

The utility model discloses a partial voltage and capacitance adjustment reactive compensation device for a three-phase four-wire power grid. The partial voltage and capacitance adjustment reactive compensation device comprises a U-phase voltage and capacitance adjustment reactive compensation unit, a V-phase voltage and capacitance adjustment reactive compensation unit, a W-phase voltage and capacitance adjustment reactive compensation unit and a control unit, wherein each phase voltage and capacitance adjustment reactive compensation unit is mainly composed of a current detection element, a voltage detection element, a full voltage compensation capacitor group, an autotransformer and a voltage adjustment capacitor group. A control mode of independent reactive compensation for each phase is adopted in the three-phase four-wire power grid, the total capacitance of each phase is identical, capacitors of each phase is equally divided into n groups, one group of the capacitors adjusts voltage and capacitance through the autotransformer, the autotransformer has m levels of output voltage in total, and each phase is compensated by n*m levels, thereby realizing multi-level fine compensation for the power grid.

Description

Three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement

Technical field

The utility model relates to the reactive power compensation of three-phase four-wire system electrical network, belongs to thyristor control shunt capacitance imaginary power automatic compensation technical field, is specifically related to a kind of three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement.

Background technology

Three-phase four-wire system electrical network has the shortcomings such as three-phase load is uneven seriously, load variations is frequent, the power-factor of load is lower, and this is unfavorable for the safe and highly efficient operation of electrical network.Reactive power compensation is to maintain Network Voltage Stability, safeguard the important means of safe operation of power system, and shunt capacitor is the important means that electrical network carries out reactive power compensation.Conventional power capacitor reactive compensation installation adopts three equal capacity switching mode simultaneously, easily causes certain phase overcompensation, and another phase is under-compensated phenomenon, and jeopardizes power grid security.The shortcomings such as conventional power capacitor reactive compensation installation also exists that compensation real-time is poor, compensation precision is low in addition and switching process impulse current is larger.In order to improve compensation precision, also there is at present employing pressure regulating and capacitance regulating reactive power compensation technique, it is according to Q _c=2 π fCU ²principle, when capacitance C mono-regularly, capacitor lead is idle Q and electric capacity both end voltage U ²be directly proportional.This reactive power compensation technology is generally usingd autotransformer as voltage adjusting device, but autotransformer itself is a kind of not only power consumption but also produce idle equipment, and autotransformer capacity is totally unfavorable to economical operation greatly.

Utility model content

Technical problem to be solved in the utility model is to provide the deficiency for the feature of three-phase four-wire system electrical network and the existence of conventional power capacitor reactive compensation installation, proposes a kind of three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement.

For addressing the above problem, the utility model is achieved through the following technical solutions:

A kind of three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement, comprise U phase, V phase and W phase pressure regulating and capacitance regulating reactive power compensating unit and control unit, wherein every phase pressure regulating and capacitance regulating reactive power compensating unit is mainly by current measuring element, voltage detector component, total head building-out capacitor group, autotransformer and pressure regulation capacitance group form;

Every phase current detecting element is connected on the live wire of this phase electrical network, and every phase voltage detecting element is connected in parallel on the live wire and zero line of this phase electrical network, and every phase current detecting element is connected with the signal output part of every phase voltage detecting element and the input of control unit;

The parallel branch that every phase total head building-out capacitor group is connected in parallel on this phase electrical network live wire and zero line by n-1 bar forms; Every branch road is in series by 1 bidirectional thyristor B1i, 1 fuse Fi, 1 inductance L i and 1 capacitor C i; The T1 end of bidirectional thyristor B1i connects the live wire of this phase electrical network, and the T2 end of bidirectional thyristor B1i is connected with the zero line of this phase electrical network with capacitor C i through fuse Fi, inductance L i; The input of the T2 end connection control unit of bidirectional thyristor B1i, the output of the G end connection control unit of bidirectional thyristor B1i; Above-mentioned i=1,2 ..., n-1; Wherein n be every phase electric capacity etc. packet count;

Every phase autotransformer has m level output voltage to have m voltage output end, and the level pressure reduction of adjacent two voltage output ends is consistent; The input of this autotransformer is connected in parallel on the live wire and zero line of this phase electrical network;

Every phase pressure regulation capacitance group is comprised of 1 capacitor C n, 1 fuse Fn and m bidirectional thyristor B2j; The T1 end of each bidirectional thyristor B2j connects a voltage output end of autotransformer, after being connected, the T2 end of all bidirectional thyristor B2j is divided into 2 tunnels, one tunnel is through fuse Fn and capacitor C n and the zero line that is connected to this phase electrical network, the input of a road connection control unit; The G end of all bidirectional thyristor B2j is all connected with the output of control unit; Above-mentioned j=1,2 ..., m; The number of the voltage output end that wherein m is autotransformer.

In such scheme, the level pressure reduction of adjacent two voltage output ends of every phase autotransformer is by unanimously designing without work difference Δ QC, $\mathrm{\&Delta;}{Q}_C=2\mathrm{\&pi;f}{C}_n(U_j^2-U_{j-1}^2)=\frac{1}{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="HDA0000391135190000011.png"\; state="\{\{state\}\}">m</figure-callout>}}2\mathrm{\&pi;f}{\mathrm{<figure-callout\; id="2"\; label="C\; n\; U"\; filenames="HDA0000391135190000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_n{U}^{}{}^2;$ Above-mentioned j=1,2 ..., m; M is the number of the voltage output end of autotransformer; F is the frequency of electrical network; Cn is the capacitance of capacitor C n; U is phase voltage.

In such scheme, described n and m are the integer that is more than or equal to 3.

The utility model is taked the control mode of every mutually independent reactive power compensation in three-phase four-wire system electrical network, each phase total capacitance is identical, every phase electric capacity is divided into n group, wherein there is one group by autotransformer pressure regulating and capacitance regulating, autotransformer has m level output voltage, every n * m shelves that are divided into mutually compensate, and n, m are more than or equal to 3 integer, realized electrical network multi-level fine is compensated.

Compared with prior art, there is following features:

1, every phase independent compensation is controlled, and avoids three-phase load imbalance to cause and respectively crosses mutually the drawback of mending or owing benefit.

2, adopt part pressure regulating and capacitance regulating control mode, improve compensation precision, reduce capacity, the loss and idle of voltage regulating transformer.

3, adopt bidirectional thyristor switching, improve the real-time of switching conversion speed and reactive power compensation, approaching zero the moment of terminal voltage of selection bidirectional thyristor drops into, and eliminates electric capacity input and causes impulse current.

4, rationally control the operating time of every branch road of total head building-out capacitor group, make the accumulative total operating time of every branch road electric capacity suitable, useful life is consistent.

Accompanying drawing explanation

Fig. 1 is a kind of theory structure schematic diagram of three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement.

Number in the figure: 1-U phase current detecting element, 2-U phase voltage detecting element, 3-U phase total head building-out capacitor group, 4-U phase autotransformer, 5-U phase pressure regulation capacitance group, 6-control unit, 7-V phase pressure regulating and capacitance regulating reactive power compensating unit, 8-W phase pressure regulating and capacitance regulating reactive power compensating unit.

Embodiment

A three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation arrangement, as shown in Figure 1, comprises U phase, V phase and W phase pressure regulating and capacitance regulating reactive power compensating unit and control unit 6.Wherein every phase pressure regulating and capacitance regulating reactive power compensating unit is mainly by current measuring element 1, voltage detector component 2, and total head building-out capacitor group 3, autotransformer 4 and pressure regulation capacitance group 5 form.

The U phase pressure regulating and capacitance regulating reactive power compensating unit of take is below elaborated to every phase pressure regulating and capacitance regulating reactive power compensating unit as example:

U phase current detecting element 1 is connected on the live wire of electrical network U phase, and U phase voltage detecting element 2 is connected in parallel on the live wire and zero line of electrical network U phase, and the signal output part of U phase current detecting element 1 and U phase voltage detecting element 2 is connected with the input of control unit 6.U phase current detecting element 1 detects size and the waveform (phase place) of U phase current.U phase voltage detecting element 2 detects size and the waveform (phase place) of U phase voltage.

U phase total head building-out capacitor group 3 is attempted by the live wire of electrical network U phase by n-1 bar and the parallel branch on zero line forms.Every branch road is in series by 1 bidirectional thyristor B1i, 1 fuse Fi, 1 inductance L i and 1 capacitor C i.The T1 end of bidirectional thyristor B1i connects the live wire of electrical network U phase, and the T2 end of bidirectional thyristor B1i is connected with the zero line of electrical network with capacitor C i through fuse Fi, inductance L i.The input of the T2 end connection control unit 6 of bidirectional thyristor B1i, the output of the G end connection control unit 6 of bidirectional thyristor B1i.Above-mentioned i=1,2 ..., n-1.Wherein n be every phase electric capacity etc. packet count.Bidirectional thyristor B1i is the switching with electrical network for this branch road.Fuse Fi is for the protection of this branch, short-circuit.The inductance value of inductance L i is less, for suppressing triple harmonic current and dropping into impulse current.It is the base components of compensation arrangement that capacitor C i produces leading idle.

U phase autotransformer 4 has m level output voltage to have m voltage output end, and the level pressure reduction of adjacent two voltage output ends is by unanimously designing without work difference, $\mathrm{\&Delta;}{Q}_C=2\mathrm{\&pi;f}{C}_n(U_j^2-U_{j-1}^2)=\frac{1}{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="HDA0000391135190000011.png"\; state="\{\{state\}\}">m</figure-callout>}}2\mathrm{\&pi;f}{\mathrm{<figure-callout\; id="2"\; label="C\; n\; U"\; filenames="HDA0000391135190000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_n{U}^{}{}^2;$ Above-mentioned j=1,2 ..., m; M is the number of the voltage output end of autotransformer 4; F is the frequency of electrical network; Cn is the capacitance of capacitor C n; U is phase voltage.The input of this autotransformer 4 is attempted by the live wire and zero line of electrical network U phase;

U phase phase pressure regulation capacitance group 5 is comprised of 1 capacitor C n, 1 fuse Fn and m bidirectional thyristor B2j.The T1 end of each bidirectional thyristor B2j connects a voltage output end of autotransformer 4, after the T2 end of all bidirectional thyristor B2j is connected, is divided into 2 tunnels, and a road is connected to the zero line of electrical network, the input of a road connection control unit 6 through fuse Fn and capacitor C n.The G end of all bidirectional thyristor B2j is all connected with the output of control unit 6.Above-mentioned j=1,2 ..., m.Wherein m is the number of the voltage output end of autotransformer 4.It is the base components of compensation arrangement that capacitor C n produces leading idle.Fuse Fn is for the short-circuit protection of capacitor C n.Bidirectional thyristor (B21, B22 ... and B2m) for the voltage of switch-capacitor Cn.

The circuit of V phase pressure regulating and capacitance regulating reactive power compensating unit 7 and W phase pressure regulating and capacitance regulating reactive power compensating unit 8 is identical with U phase pressure regulating and capacitance regulating reactive power compensating unit circuit structure, and parameter is consistent.Said n and m are the integer that is more than or equal to 3.

The three-phase four-wire system electrical network part pressure regulating and capacitance regulating reactive power compensation method that said apparatus is realized, comprises the steps:

1. control unit 6 is according to the detected monophase current signal of current measuring element 1 and the detected single-phase voltage signal of voltage detector component 2, calculate idle amount Q, Q=UIsin φ wherein, in formula, U is phase voltage value, I is phase current values, and φ is the phase place of phase voltage and electric current.

2. control unit 6 calculates the switching of electric capacity according to idle amount Q, selects the input of total head building-out capacitor group 3 to prop up the operating voltage of way and pressure regulation capacitance group 5.In the utility model, reactive power compensation worst error is that precision is

above-mentioned j=1,2 ..., m; M is the number of the voltage output end of autotransformer 4; F is the frequency of electrical network; Cn is the capacitance of capacitor C n; U is phase voltage.

3. capacitor C 1 in control unit 6 accumulative total total head building-out capacitor groups 3, C2 ... with the operating time separately of Cn-1; If need to increase input branch road, select short branch road of accumulative total operating time to drop into, if need to reduce, drop into branch road, select the branch road of accumulative total longevity of service to cut off;

4. according to the characteristic of bidirectional thyristor, need to when bidirectional thyristor is zero, drop into avoid electric capacity to drop into and cause impulse current.As will be dropped into total head building-out capacitor group 3 time, control unit 6 detects the terminal voltage of bidirectional thyristor B1i, and selects the terminal voltage of bidirectional thyristor B1i to approach moment of zero and drop into.While pressing capacitance group 5 to drop into as exchanged, control unit 6 detects the terminal voltage of bidirectional thyristor B2j, selects approaching zero the moment of terminal voltage of bidirectional thyristor B2j to drop into.

5. control unit 6 calculates the idle reduction Δ Q that capacitive branch drops into front and back Reactive Quantity of Power Network Q, and by idle reduction Δ Q and the new idle value of the theory Q that drops into capacitive branch _ccompare, wherein Q _c=2 π fCU ², the frequency that in formula, f is electrical network, C is the capacitance of switching branch road; U capacitance terminal magnitude of voltage; If idle reduction Δ Q and theoretical idle value Q _cdifference in allowed limits, illustrate that the capacitive branch of switching is working properly, and indicate this capacitive branch normal operating conditions; If idle reduction Δ Q and theoretical idle value Q _cdifference having surpassed the scope allowing, the capacitive branch operation irregularity of switching be described, and indicate this capacitive branch abnormal work state.

Claims (3)

1. The partial voltage regulation and capacity regulation reactive power compensation device of the three-phase four-wire power grid is characterized in that it includes a U-phase, V-phase and W-phase voltage regulation and capacity regulation reactive power compensation unit and a control unit (6), wherein each phase regulation The voltage regulating reactive power compensation unit is mainly composed of a current detection element (1), a voltage detection element (2), a full voltage compensation capacitor group (3), an autotransformer (4) and a voltage regulation capacitor group (5); The current detection element (1) of each phase is connected in series with the live wire of the phase grid, and the voltage detection element (2) of each phase is connected in parallel with the live wire and neutral wire of the phase grid. The current detection element (1) of each phase and the voltage detection of each phase The signal output terminal of the component (2) is connected with the input terminal of the control unit (6); Each phase full-voltage compensation capacitor group (3) is composed of n-1 parallel branches connected in parallel to the live wire and neutral wire of the phase grid; each branch consists of 1 bidirectional thyristor B1i, 1 fuse Fi, 1 An inductor Li and a capacitor Ci are connected in series; the T1 terminal of the bidirectional thyristor B1i is connected to the live line of the phase grid, and the T2 terminal of the bidirectional thyristor B1i is connected to the neutral line of the phase grid through the fuse Fi, the inductor Li and the capacitor Ci; The T2 terminal of the bidirectional thyristor B1i is connected to the input terminal of the control unit (6), and the G terminal of the bidirectional thyristor B1i is connected to the output terminal of the control unit (6); the above i=1, 2, ..., n-1; where n is each The number of equal groups of phase capacitance; Each phase autotransformer (4) has m-level output voltage, that is, it has m voltage output terminals, and the step voltage difference between two adjacent voltage output terminals is consistent; the input terminal of the autotransformer (4) is connected in parallel to the live wire of the phase grid and zero line; Each phase voltage regulating capacitor group (5) is composed of a capacitor Cn, a fuse Fn and m bidirectional thyristors B2j; the T1 end of each bidirectional thyristor B2j is connected to a voltage output end of the autotransformer (4), all The T2 ends of the bidirectional thyristors B2j are connected and divided into two circuits, one of which is connected to the neutral line of the phase power grid through the fuse Fn and the capacitor Cn, and the other is connected to the input terminal of the control unit (6); the G terminals of all the bidirectional thyristors B2j are connected to The output terminals of the control unit (6) are connected; the above j=1, 2, ..., m; wherein m is the number of voltage output terminals of the autotransformer (4). the 2. The reactive power compensation device for partial voltage regulation and capacity regulation of the three-phase four-wire power grid according to claim 1, characterized in that: the step voltage difference between two adjacent voltage output terminals of each phase autotransformer (4) is based on the reactive power difference ΔQ _C consistent to design, that is

The above j=1, 2, ..., m; m is the number of voltage output terminals of the autotransformer (4); f is the frequency of the grid; Cn is the capacitance value of the capacitor Cn; U is the phase voltage. 3. The reactive power compensation device for partial voltage regulation and capacity regulation of a three-phase four-wire power grid according to claim 1 or 2, characterized in that: said n and m are both integers greater than or equal to 3. the

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