CN101902048B - High-speed railway negative-sequence and harmonic compensation system based on two-phase three-wire system converter - Google Patents

Abstract

The invention discloses a high-speed railway negative-sequence and harmonic compensation system based on a two-phase three-wire system converter, comprising two single-phase reducing transformers and a two-phase three-wire system converter, wherein the primary sides of the two single-phase reducing transformers are connected with two single-phase power-supply arms arranged in a three-phase V/V tractive power-supply system, and both ends of the secondary sides of the two single-phase reducing transformers are connected correspondingly with the primary sides, thereby the secondary sides of the two single-phase reducing transformers form three wires; the two-phase three-wire system converter comprises three switch arms, wherein one switch arm is connected with two single-phase voltage shared ground wires, and the other two switch arms are respectively connected with the other two wires in the secondary sides of the two single-phase reducing transformers by an inductor. Compared with two common single-phase converters, the high-speed railway negative-sequence and harmonic compensation system reduces one switch arm and does not increase the current level of a switch device. Compared with the common three-phase converter, the high-speed railway negative-sequence and harmonic compensation system reduces one output inductor to save cost, and the voltage utilization of a direct current side is one time higher.

Description

High-speed railway negative-sequence and harmonic wave bucking-out system based on the two-phase three wire system current transformer

Technical field

The present invention relates to a kind of high-speed railway negative-sequence and harmonic wave comprehensive compensation system, particularly a kind of high-speed railway negative-sequence and harmonic wave bucking-out system based on the two-phase three wire system current transformer.

Background technology

The high-speed railway tractive power supply system is owing to adopt the single phase power supply mode, produce negative-sequence current, bring serious harm for the operation of generating, transmission of electricity and converting equipment in the electric power system, for example increase the loss of generator, reduce that transformer is exerted oneself etc., have a strong impact on the safety and economic operation of electric power system.In addition, the harmonic wave of high-speed railway electric locomotive generation has also reduced the reliability of its electric power system and higher level's electric power system.Therefore, must adopt an effective measure and suppress negative phase-sequence and the harmonic current that the high-speed railway electric power system produces.

At negative phase-sequence, the harmonic problem of electric railway, some indemnifying measures have appearred both at home and abroad.The negative sequence compensation that two supply arms that adopt SVC to be installed in traction transformer carry out electric railway, in theory can be with the negative phase-sequence full remuneration under the situation that traction transformer capacity allows, but increased the capacity of traction transformer and exerted oneself, and reduced by two supply arm power factors.Take single-phase active power filter can realize the harmonic wave of electric railway is suppressed, but can not effectively compensate the negative-sequence current in the electric railway.Single phase power supply characteristic at the railway power supply system, the Japan scholar has proposed railway power regulator (Railway Static Power Conditioner, RPC), utilize that back-to-back two single-phase converters are gained merit, the control of idle and harmonic wave, can realize negative phase-sequence and harmonic wave comprehensive compensation, but two single-phase converters comprise 8 device for power switching, and device for power switching is more, and its concrete structure is seen Fig. 1.In addition, also have the scholar to propose a kind of three-phase active bucking-out system---active power quality compensator (Active Power Quality Compensator, APQC), its structure is to adopt the Scott transformer that two single-phase electricity are transformed to three-phase equilibrium voltage, again a 3-phase power converter is electrically connected with three-phase equilibrium by three outputting inductances, saved an arm device for power switching than RPC, but increased the electric pressure of power device, and need the complicated Scott transformer of structure and many outputting inductances, its concrete structure is seen Fig. 2.

Summary of the invention

In order to solve the problems of the technologies described above, the invention provides a kind of high-speed railway negative-sequence based on the two-phase three wire system current transformer and harmonic wave bucking-out system.

The technical scheme that the present invention solves the problems of the technologies described above is: comprise two single phase step-down transformers, described two former limits of single phase step-down transformer are connected with two single phase power supply arms in the three-phase V/V tractive power supply system, two ends corresponding with former border district in the two single-phase transformer secondary couple together, thereby make two single phase step-down transformer secondary form three lines, it is characterized in that: also comprise a two-phase three wire system current transformer, described two-phase three wire system current transformer comprises three switch arms, wherein a switch arm and two single-phase voltages share ground wire and are connected, and all the other two switch arms pass through an inductance respectively and are connected with all the other two lines in the two single phase step-down transformer secondary.

Technique effect of the present invention is: two-phase three wire system converter switches device is few in (1) this system, than RPC take two back-to-back single-phase converter lack 2 device for power switching; Adopt better simply two single-phase transformers of structure to have only two two-phase three wire system current transformer to be connected two single-phase voltages and outputting inductance, the Scott transformer device structure that adopts than active power quality compensator APQC is simple, and will lack 1 outputting inductance.

(2) fundamental voltage amplitude of each phase offset current of two-phase three wire system current transformer equates.That is to say that the current class that shares an arm switch device of ground wire in the two-phase three wire system current transformer does not increase, novel bucking-out system has more embodied its structural advantage.

(3) the dc voltage utilance of two-phase three wire system current transformer doubles than common three-phase system current transformer, can reduce the cost of dc bus capacitor; (4) by regulating the state that cut-offs of 3 switch brachium pontis, the dc voltage that can keep the two-phase three wire system current transformer is stable, and regulates the output current of two-phase three wire system current transformer, realizes negative phase-sequence and harmonic wave comprehensive compensation to the high-speed railway electric power system.

The present invention is further illustrated below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the structure chart of RPC.

Fig. 2 is the structure chart of APQC.

Fig. 3 is structure chart of the present invention.

Fig. 4 is circuit diagram of the present invention.

Fig. 5 is the switch model of two-phase three wire system current transformer.

Fig. 6 is equivalent circuit diagram of the present invention.

Fig. 7 is negative sequence compensation schematic diagram of the present invention.

Embodiment

Referring to Fig. 3, Fig. 3 is structure chart of the present invention.The present invention 4 target compensation is for adopting the high-speed railway electric power system of three-phase V/V traction transformer 1.The present invention 4 is made up of two single phase step-down transformers 2 and two-phase three wire system current transformer 3.The former limit of two single-phase transformers is connected with two single-phase traction power supply arms respectively, and two ends corresponding with former border district in the two single-phase transformer secondary are coupled together, thereby forms three lines.The three-phase that the transformer secondary forms is connected with the two-phase three wire system current transformer.The two-phase three wire system current transformer is by common three brachium pontis current transformers and two outputting inductance L _αAnd L _βConstitute, the output of corresponding connection with ground wire does not have outputting inductance in the current transformer.The supply arm that is connected with three-phase V/V transformer secondary ac end among the definition figure is the α phase, and another arm is the β phase.

The present invention and APQC have relatively adopted two single-phase transformers, and its structure wants simple with respect to the Scott transformer, and outputting inductance only needs 2; Compare with RPC, saved an arm device for power switching.Therefore, this collocation structure is more simplified.

Operation principle and effect below in conjunction with accompanying drawing 4,5,6,7 pairs of comprehensive compensation systems are further elaborated.

Referring to Fig. 4, Fig. 4 is equivalent circuit diagram of the present invention.If three-phase V/V transformer voltage ratio is k _v, two single-phase transformer no-load voltage ratios are k _s, be current source with the locomotive load equivalent.Ignore inductance resistance, supply arm net side impedance difference equivalence mutually is inductance L to α with β _{S α}And L _{S β}, two-phase three wire system current transformer 1 equivalent transformation is ignored electric network impedance to the 27.5kV side, order: $\left\{\begin{array}{c}{L}_{\mathrm{\αs}}=\frac{L_{\mathrm{\α}}}{k_s}\\ L_{\mathrm{\βs}}=\frac{L_{\mathrm{\β}}}{k_s}\end{array}\right.---\left(1\right)$ Referring to Fig. 5, Fig. 5 is the switch model of two-phase three wire system current transformer.Using the switching circuit modeling method is shown in Figure 5 with two-phase three wire system current transformer 1 equivalence among Fig. 2.The state that cut-offs of each brachium pontis in the corresponding diagram 5, the definition switch function is

S in the following formula _i(i=α, n, β) state that cut-offs of the switch brachium pontis that connects of corresponding α phase, ground wire, β phase.

According to Kirchhoff's law and Fig. 5 circuit relationships, can obtain its voltage-current relationship equation $\left\{\begin{array}{c}{L}_{\mathrm{\αe}}\frac{{\mathrm{di}}_{\mathrm{c\α}}}{\mathrm{dt}}+u_{\mathrm{\αinv}}-u_{\mathrm{\α}}=0\\ L_{\mathrm{\βe}}\frac{{\mathrm{di}}_{\mathrm{c\β}}}{\mathrm{dt}}+u_{\mathrm{\βinv}}-u_{\mathrm{\β}}=0\\ i_{\mathrm{c\α}}+i_{\mathrm{c\β}}+i_{\mathrm{cn}}=0\end{array}\right.---\left(3\right)$ In the following formula, u _{α inv}And u _{β inv}Represent two-phase three wire system current transformer α phase and β output voltage mutually respectively.

Break-make situation according to switching device can obtain $\left\{\begin{array}{c}{u}_{\mathrm{\αinv}}=(S_{\mathrm{\α}}-S_n)u_{\mathrm{dc}}\\ u_{\mathrm{\βinv}}=(S_{\mathrm{\β}}-S_n)u_{\mathrm{dc}}\end{array}\right.---\left(4\right)$ Can find u from following formula _{α inv}And u _{β inv}U is arranged _Dc, 0 and-u _DcThree kinds of states, and the maximum output voltage of common three-phase inverter is

As seen the dc voltage utilance of two-phase three wire system current transformer doubles than common three-phase inverter.

With (4) substitution (3), can get $\left\{\begin{array}{c}{L}_{\mathrm{\αe}}\frac{{\mathrm{di}}_{\mathrm{c\α}}}{\mathrm{dt}}+(S_{\mathrm{\α}}-S_n)u_{\mathrm{dc}}-u_{\mathrm{\α}}=0\\ L_{\mathrm{\βe}}\frac{{\mathrm{di}}_{\mathrm{c\β}}}{\mathrm{dt}}+(S_{\mathrm{\β}}-S_n)u_{\mathrm{dc}}-u_{\mathrm{\β}}=0\\ i_{\mathrm{cn}}=-(i_{\mathrm{c\α}}+i_{\mathrm{c\β}})\end{array}\right.---\left(5\right)$ From formula (5) as can be seen, two-phase three wire system current transformer α phase current obtains by regulating with the switch brachium pontis switching signal that α is connected with ground wire mutually, and the β phase current obtains by regulating with the switch brachium pontis switching signal that β is connected with ground wire mutually.Can find that the switch arm that is connected with ground wire is being controlled α mutually and the β phase current in fact simultaneously.Therefore, the two-phase three wire system current transformer can be considered as two single-phase converters, these two single-phase converters share the switch brachium pontis that is connected with ground wire, and the common DC lateral capacitance.By regulating the state that cut-offs of 3 switch brachium pontis, can regulate two-phase three wire system current transformer α mutually and the β phase current, also just correspondingly regulated ground line current; By suitable adjustable, it is stable to keep dc voltage, realizes the meritorious transfer between two supply arms, and compensating reactive power and harmonic wave, thereby realizes negative phase-sequence and harmonic synthesis compensation to the high-speed railway electric power system.

Referring to Fig. 6, Fig. 6 is equivalent circuit diagram of the present invention.According to top analysis as can be known, the two-phase three wire system current transformer can be considered the merging of two single-phase converters and forms, and therefore can control it as controlled current source I _{C α}And I _{C β}, map of current of the present invention can equivalence be shown in Figure 6.Can be got by Fig. 6 $\left\{\begin{array}{c}{I}_{\mathrm{\α}}=I_{\mathrm{c\α}}+I_{\mathrm{L\α}}\\ I_{\mathrm{\β}}=I_{\mathrm{c\β}}+I_{\mathrm{L\β}}\end{array}\right.---\left(6\right)$ Referring to Fig. 7, Fig. 7 is the schematic diagram of comprehensive compensation system compensation negative-sequence current.Be benchmark with A phase voltage phase place in the three-phase voltage, because the high-speed railway locomotive adopts PWM four-quadrant rectification control mode, phasor power factor is approximately 1.Then two supply arm load currents can be expressed as $\left\{\begin{array}{c}{I}_{\mathrm{L\α}}=I_{\mathrm{L\αf}}{e}^{-j\frac{\mathrm{\π}}{6}}+I_{\mathrm{L\αh}}\\ I_{\mathrm{L\β}}=I_{\mathrm{L\βf}}{e}^{-j\frac{\mathrm{\π}}{2}}+I_{\mathrm{L\βh}}\end{array}\right.---\left(7\right)$ In the formula (7), I _{L α f}, I _{L β f}Be respectively the first-harmonic composition amplitude of α, β phase load electric current, I _{L α h}, I _{L β h}Represent α, β phase load harmonic current summation respectively.

Analyze the negative sequence compensation principle and only consider the first-harmonic composition, each variable among Fig. 5 is all only represented the first-harmonic composition.Can be expressed as according to the former limit of formula (7) V/V transformer three-phase current $\left\{\begin{array}{c}{I}_A=\frac{I_{\mathrm{L\αf}}}{k_v}{e}^{-j\frac{\mathrm{\π}}{6}}\\ I_B=\frac{I_{\mathrm{L\βf}}}{k_v}{e}^{-j\frac{\mathrm{\π}}{2}}\\ I_C=-(I_A+I_B)\end{array}\right.---\left(8\right)$ Shifting the amplitude size by the two-phase three wire system current transformer between two single phase power supply arms is half of two supply arm active current differences

Active current, two supply arm net side active currents are equated, then three-phase current becomes the I ' shown in Fig. 7 _A, I ' _BAnd I ' _C, its value is $\left\{\begin{array}{c}{I}_A^{\&prime;}=\frac{(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{2k_v}{e}^{-j\frac{\mathrm{\&pi;}}{6}}\\ I_B^{\&prime;}=\frac{(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{2k_v}{e}^{-j\frac{\mathrm{\&pi;}}{2}}\\ I_C^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{2k_{\mathrm{<figure-callout\; id="2"\; label="v\; e\; j"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">v</figure-callout>}}}{e}^j{\frac{2\mathrm{\&pi;}}{3}}^{}\end{array}\right.---\left(9\right)$ As can be seen from Figure 7, this moment three-phase current I ' _A, I ' _BAnd I ' _CImbalance makes moderate progress, but three-phase current lack of equilibrium also.From Fig. 7 as seen, also need in the certain reactive current of two single phase power supply arms compensation, reactive current amplitude size is $I_{\mathrm{\&alpha;q}}=I_{\mathrm{\&beta;q}}=\frac{1}{2}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})\&CenterDot;\tan \frac{\mathrm{\&pi;}}{6}---\left(10\right)$ I wherein _{α q}And I _{β q}Be respectively the reactive current amplitude of two-phase three wire system current transformer compensation.

Behind the compensating reactive power electric current, net side three-phase current becomes I " _A, I " _B, I " _C, as can be seen from Figure 7: $\left\{\begin{array}{c}{I}_A^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3k_t}{e}^{j0}\\ I_B^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3k_t}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{3}}\\ I_C^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3k_{\mathrm{<figure-callout\; id="2"\; label="t\; e\; j"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">t</figure-callout>}}}{e}^j{\frac{2\mathrm{\&pi;}}{3}}^{}\end{array}\right.---\left(11\right)$ From following formula as seen, after compensation, three-phase current is balance.

Because the locomotive load also contains a spot of harmonic wave, bucking-out system also should be sent corresponding harmonic compensation current and remove to offset the load harmonic wave.Three-phase current behind compensation negative phase-sequence and the harmonic wave should be as the formula (11).According to three-phase V/V transformer characteristic, can learn that compensation back α, β phase supply arm electric current are: $\left\{\begin{array}{c}{I}_{\mathrm{\&alpha;}}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3}{e}^{j0}\\ I_{\mathrm{\&beta;}}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{3}}\end{array}\right.---\left(12\right)$ According to Fig. 3 I as can be known _{T α i}=k _sI _α(n) (13) are got the offset current of two-phase three wire system current transformer by formula (5), (6), (7), (12), (13) simultaneous solution for i=α, β $\left\{\begin{array}{c}{I}_{\mathrm{tc\&alpha;}}=\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{-j\frac{\mathrm{\&pi;}}{6}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})e^{j\frac{\mathrm{\&pi;}}{3}}\\ -k_s{I}_{\mathrm{L\&alpha;h}}\\ I_{\mathrm{tc\&beta;}}=\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{j\frac{\mathrm{\&pi;}}{2}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})e^{\mathrm{j\&pi;}}\\ -k_s{I}_{\mathrm{L\&beta;h}}\\ I_{\mathrm{tcn}}=-\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{j\frac{\mathrm{\&pi;}}{6}}-\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}}){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="HDA0000024037640000011.png,HDA0000024037640000021.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\\ +k_s{I}_{\mathrm{L\&alpha;h}}+k_s{I}_{\mathrm{L\&beta;h}}\end{array}\right.---\left(14\right)$ From formula (14) as can be seen, the fundamental voltage amplitude of each phase offset current of two-phase three wire system current transformer equates.That is to say that the current class that shares an arm switch device of ground wire in the two-phase three wire system current transformer does not increase, novel bucking-out system has more embodied its structural advantage.

Claims (1)

1. high-speed railway negative-sequence and harmonic wave bucking-out system based on a two-phase three wire system current transformer, comprise two single phase step-down transformers, described two former limits of single phase step-down transformer are connected with two single phase power supply arms in the three-phase V/V tractive power supply system, two ends corresponding with former border district in the two single-phase transformer secondary couple together, thereby make two single phase step-down transformer secondary form three lines, it is characterized in that: also comprise a two-phase three wire system current transformer, described two-phase three wire system current transformer comprises three switch arms, wherein a switch arm and two single-phase voltages share ground wire and are connected, and all the other two switch arms pass through an inductance respectively and are connected with all the other two lines in the two single phase step-down transformer secondary.

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