CN201774261U - High-speed railway negative sequence and harmonic compensation system based on two-phase three-wire system converter - Google Patents

Abstract

The utility model discloses a high-speed railway negative sequence and harmonic compensation system based on a two-phase three-wire system converter. The high-speed railway negative sequence and harmonic compensation system comprises two single-phase voltage-reduction transformers and the two-phase three-wire system converter, wherein primary sides of the two single-phase voltage-reduction transformers are connected with two single-phase power supply arms in a three-phase V/V traction power supply system; two ends in secondary sides of the two single-phase transformers, corresponding to the primary sides, are connected, thus enabling the secondary sides of the two single-phase voltage-reduction transformers to form three wires; and the two-phase three-wire system converter comprises three switch arms, wherein one switch arm is connected with a grounding wire shared by two single-phase voltages, and the other two switch arms are respectively connected with the other two wires in the secondary sides of the two single-phase voltage-reduction transformers through an inductor. The high-speed railway negative sequence and harmonic compensation system omits one switch arm compared with two common single-phase converters, and one output inductor compared with the common three-phase converter, thus saving cost.

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 utility model 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 under the situation that traction transformer capacity allows with the negative phase-sequence full remuneration, 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 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 needed the complicated Scott transformer of structure and many outputting inductances, its structure is seen Fig. 2.

Summary of the invention

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

The technical scheme that the utility model 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-way, 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 is connected with the shared ground wire of two single-phase voltages, and all the other two switch arms are connected with all the other two lines in the two single phase step-down transformer secondary by inductance respectively.

Technique effect of the present utility model 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 of an arm switch device of shared ground wire does not increase in the two-phase three wire system current transformer, novel bucking-out system has more embodied its structural advantage.

(3) 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.

Below in conjunction with accompanying drawing the utility model is further described.

Description of drawings

Fig. 1 is the structure chart of RPC.

Fig. 2 is the structure chart of APQC.

Fig. 3 is a structure chart of the present utility model.

Fig. 4 is a circuit diagram of the present utility model.

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

Fig. 6 is an equivalent circuit diagram of the present utility model.

Fig. 7 is a negative sequence compensation schematic diagram of the present utility model.

Embodiment

Referring to Fig. 3, Fig. 3 is a structure chart of the present utility model.The target compensation of the utility model 4 is for adopting the high-speed railway electric power system of three-phase V/V traction transformer 1.The utility model 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-way.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 connects with three-phase V/V transformer secondary ac end among the definition figure be α mutually, another arm is a phase.

The utility model 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 4,5,6,7 pairs of comprehensive compensation systems of accompanying drawing are further elaborated.

Referring to Fig. 4, Fig. 4 is an equivalent circuit diagram of the present utility model.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 an 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: $\left\{\begin{array}{c}{L}_{\mathrm{\αe}}=\frac{L_{\mathrm{\α}}}{k_s}\\ L_{\mathrm{\βe}}=\frac{L_{\mathrm{\β}}}{k_s}\end{array}\right.---\left(1\right)$ Referring to Fig. 5, Fig. 5 is the switch model of two-phase three wire system current transformer.Utilization switching circuit modeling method is shown in Figure 5 with 1 equivalence of the two-phase three wire system current transformer 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 connected 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, with the switch arm that ground wire connects controlling in fact simultaneously α mutually with the β phase current.Therefore, the two-phase three wire system current transformer can be considered as two single-phase converters, the shared switch brachium pontis that is connected with ground wire of these two single-phase converters, and 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 phase and 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 an equivalent circuit diagram of the present utility model.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 utility model can equivalence be shown in Figure 6.Can get 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.With A phase voltage phase place in the three-phase voltage is benchmark, 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 $\left\{\begin{array}{c}{I}_A^{\&prime;}=\frac{(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{2k_v}{e}^{-j\frac{\mathrm{\&pi;}}{6}}\\ I_B^{\&prime;}=\frac{(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{{2k}_v}{e}^{-j\frac{\mathrm{\&pi;}}{2}}\\ I_C^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{{3k}_{\mathrm{<figure-callout\; id="2"\; label="v\; e\; j"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">v</figure-callout>}}}{e}^j{\frac{2\mathrm{\&pi;}}{3}}^{}\end{array}\right.---\left(9\right)$ 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 _Aa, I _Ba, I _Ca, as can be seen from Figure 7: $\left\{\begin{array}{c}{I}_A^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3k_t}{e}^{j0}\\ I_B^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{{3k}_t}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{3}}\\ I_C^{\&prime;}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{{3\mathrm{<figure-callout\; id="2"\; label="k\; t\; e"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_t}{e}^{}{}^{\frac{2\mathrm{\&pi;}}{3}}\end{array}\right.---\left(11\right)$ 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: $\left\{\begin{array}{c}{I}_{\mathrm{\&alpha;}}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3}{e}^{j0}\\ I_{\mathrm{\&beta;}}=\frac{\sqrt{3}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})}{3}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{3}}\end{array}\right.---\left(12\right)$ According to Fig. 3 I as can be known _Tci=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 $\left\{\begin{array}{c}{I}_{\mathrm{tc\&alpha;}}=\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{-j\frac{\mathrm{\&pi;}}{6}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})e^{j\frac{\mathrm{\&pi;}}{3}}\\ -k_s{I}_{\mathrm{L\&alpha;h}}\\ I_{\mathrm{tc\&beta;}}=\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{j\frac{\mathrm{\&pi;}}{2}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}})e^{\mathrm{j\&pi;}}\\ -k_s{I}_{\mathrm{L\&beta;h}}\\ I_{\mathrm{tcn}}=-\frac{k_s}{2}(I_{\mathrm{L\&beta;f}}-I_{\mathrm{L\&alpha;f}})e^{j\frac{\mathrm{\&pi;}}{6}}-\frac{{\mathrm{<figure-callout\; id="2"\; label="k\; s"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">k</figure-callout>}}_s}{2\sqrt{3}}(I_{\mathrm{L\&alpha;f}}+I_{\mathrm{L\&beta;f}}){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="HDA0000024038260000011.png,HDA0000024038260000021.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\\ +k_s{I}_{\mathrm{L\&alpha;h}}+k_s{I}_{\mathrm{L\&beta;h}}\end{array}\right.---\left(14\right)$ 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 of an arm switch device of shared ground wire does not increase in the two-phase three wire system current transformer, 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-way, 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 is connected with the shared ground wire of two single-phase voltages, and all the other two switch arms are connected with all the other two lines in the two single phase step-down transformer secondary by inductance respectively.

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