阅读说明：本技术 半容量同相供电变流器 (Half-capacity cophase power supply converter ) 是由 隋明飞 孟岩 于 2021-02-01 设计创作，主要内容包括：本发明公开了一种半容量同相供电变流器,涉及电力控制技术领域,由多绕组变压器三相-单相AC-AC变流器组成。多绕组变压器原边包括七个绕组,多绕组变压器的原边三个绕组连接到三相交流电网,三个副边绕组连接到三相-单相AC-AC变流器的输入侧,三相-单相AC-AC变流器的输出侧与多绕组变压器的第四个绕组串联之后连接到电气化铁路牵引接触网和钢轨。通过控制所述的三相-单相AC-AC变流器的输入侧电流,可以实现多绕组变压器的原边三个绕组单位功率因数运行,即输入电流不存在无功电流,且没有负序电流。所述的三相-单相AC-AC变流器的单相输出侧电流与牵引变电所向接触网供电的电流相同,而输出电压和为接触网电压的一半,可以减小电力电子装置的容量和造价。(The invention discloses a half-capacity cophase power supply converter, relates to the technical field of power control, and consists of a multi-winding transformer three-phase-single-phase AC-AC converter. The primary side of the multi-winding transformer comprises seven windings, three windings of the primary side of the multi-winding transformer are connected to a three-phase alternating-current power grid, three secondary windings of the multi-winding transformer are connected to the input side of a three-phase-single-phase AC-AC converter, and the output side of the three-phase-single-phase AC-AC converter is connected with a fourth winding of the multi-winding transformer in series and then connected to a traction contact net and a steel rail of the electrified railway. By controlling the input side current of the three-phase-single-phase AC-AC converter, the unit power factor operation of three primary windings of the multi-winding transformer can be realized, namely, the input current has no reactive current and no negative sequence current. The single-phase output side current of the three-phase-single-phase AC-AC converter is the same as the current supplied by the traction substation to the contact network, and the sum of the output voltage and the voltage of the contact network is half of the voltage of the contact network, so that the capacity and the manufacturing cost of the power electronic device can be reduced.)

1. Half capacity cophase supply converter, its characterized in that: the half-capacity cophase power supply converter consists of a multi-winding transformer and a three-phase single-phase AC-AC converter; the multi-winding transformer comprises seven windings, one connecting terminal of a first winding is T1, and the other connecting terminal of the first winding is connected to a point N1; one connection terminal of the second winding is T2, and the other connection terminal of the second winding is connected to point N1; one connection terminal of the third winding is T3, and the other connection terminal of the third winding is connected to a point N1; one connection terminal of the fourth winding is T4, and the other connection terminal of the fourth winding is connected to a point N2; one connection terminal of the fifth winding is T5, and the other connection terminal of the fifth winding is connected to point N2; one connection terminal of the sixth winding is T6, and the other connection terminal of the sixth winding is connected to point N2; one connection terminal of the seventh winding is T7, and the other connection terminal of the seventh winding is T8; the three-phase-single-phase AC-AC converter is provided with five connecting terminals Ta, Tb, Tc, Tx and Ty; the winding terminal T1 of the multi-winding transformer is connected to the A phase of the three-phase alternating current power grid, the winding terminal T2 is connected to the B phase of the three-phase alternating current power grid, and the winding terminal T3 is connected to the C phase of the three-phase alternating current power grid; t4 is connected to the Ta terminal of the three-phase to single-phase AC-AC converter, T5 is connected to the Tb terminal of the three-phase to single-phase AC-AC converter, T6 is connected to the Tc terminal of the three-phase to single-phase AC-AC converter; the T7 is connected to the Ty terminal of the three-phase-single-phase AC-AC converter, and the T8 is connected to the steel rail; the Tx terminal of the three-phase-single-phase AC-AC converter is connected to an overhead line system.

2. A half-capacity co-phase fed converter according to claim 1, characterized in that: the winding voltage u of the multi-winding transformer_T4N2And u_T1N1In phase, u_T5N2And u_T2N1In phase, u_T6N2And u_T3N1In phase, u_T7T8And u_T3N1In phase; the winding voltage u of the multi-winding transformer_T4N2、u_T5N2、u_T6N2、u_T7T8And a connection terminal voltage u of the three-phase-single-phase AC-AC converter_TxTyAre all equal in amplitude and are 1/2 of the supply voltage between the catenary and the rail.

3. A half-capacity co-phase fed converter according to claim 1, characterized in that: the input currents of Ta, Tb and Tc connecting terminals of the three-phase-single-phase AC-AC converter are i respectively_a、i_bAnd i_cThe output current of a seventh winding terminal T7 of the multi-winding transformer winding is i_f(ii) a The lag 240 DEG electrical angle operator is represented by alpha, alpha x represents an instantaneous value that lags the real-time variable x by 240 DEG electrical angle, alpha²x represents an instantaneous value that lags the real-time variable x by 120 electrical degrees; i.e. i_a、i_bAnd i_cThe positive sequence component of (a) is obtained as follows: i.e. i_a+＝(i_a+αi_b+α²i_c)/3，i_b+＝(α²i_a+i_b+αi_c)/3，i_c+＝(αi_a+α²i_b+i_c)/3。

i_a、i_bAnd i_cThe negative sequence component of (a) is obtained as follows: i.e. i_a-＝(i_a+α²i_b+αi_c)/3，i_b-＝(αi_a+i_b+α²i_c)/3，i_c-＝(α²i_a+αi_b+i_c)/3。

The real-time phase of the sine alternating voltage of the A-phase power grid is theta, the real-time phase of the sine alternating voltage of the B-phase power grid is theta-120 degrees, and the sine of the C-phase power grid is crossedThe real-time phase of the current voltage is theta-240 DEG, i_a+、i_b+And i_c+The reactive component of (a) is obtained as follows:

i_a+q＝I_qabc+×cos(θ)，i_b+q＝I_qabc+×cos(θ-120°)，i_c+q＝I_qabc+xcos (. theta. -240 ℃ C.). Wherein, I_qabc+＝[i_a+×cos(θ)+i_b+×cos(θ-120°)+i_c+×cos(θ-240°)]×2/3。

i_fThe positive sequence component of (a) is obtained as follows: i.e. i_fa+＝α²i_f/3，i_fb+＝αi_f/3，i_fc+＝i_f/3。i_fThe negative sequence component of (a) is obtained as follows: i.e. i_fa-＝αi_f/3，i_fb-＝α²i_f/3，i_fc-＝i_f/3。

i_fa+、i_fb+And i_fc+The reactive component of (a) is obtained as follows:

i_fa+q＝I_qf+×cos(θ)，i_fb+q＝I_qf+×cos(θ-120°)，i_fc+q＝I_qf+xcos (. theta. -240 ℃ C.). Wherein, I_qf+＝[i_fa+×cos(θ)+i_fb+×cos(θ-120°)+i_fc+×cos(θ-240°)]×2/3。

4. A half-capacity co-phase fed converter according to claim 3, characterized in that: the three-phase-single-phase AC-AC converter enables the i to be controlled in a closed loop mode_a-、i_b-、i_c-、i_fa-、i_fb-、i_fc-、i_a+q、i_b+q、i_c+q、i_fa+q、i_fb+q、i_fc+qThe following relationship is satisfied:

i_a-+i_fa-＝i_b-+i_fb-＝i_c-+i_fc-＝0，i_a+q+i_fa+q＝i_b+q+i_fb+q＝i_c+q+i_fc+q＝0。

Technical Field

The invention relates to the technical field of power control, in particular to a co-phase power supply converter of an electrified railway traction power supply system with the capacity of the converter being half of the power supply capacity and a control method.

Background

The traction power supply system of the electrified railway is a power supply system for providing electric power for traction of an electric locomotive and mainly comprises a traction substation and a contact network. Traction substations generally convert alternating current of a three-phase public power grid into an electric energy form suitable for electric locomotives, and the electric energy form is sent to a contact network, and then the locomotive is supplied with power by the contact network.

Because an electric locomotive generally needs single-phase power supply, an existing traction power supply system of the electrified railway generally adopts a sectional and split-phase mode to supply power to the electric locomotive (i.e. a contact network generally adopts a sectional power supply mode, and different power supply sections only adopt a certain phase in a three-phase power grid to supply power). Between the different power supply sections there is usually provided an electrically non-conductive insulation zone (neutral section) through which the electric locomotive is not able to obtain power supply when passing. In the process, the traction and speed loss of the electric locomotive is caused, and the train is in a single-phase power supply mode, so that negative sequence current is generated in a three-phase power grid, and the negative sequence current is caused in the three-phase power grid, and the negative sequence current is more serious along with the increase of the power of the electric locomotive.

At present, a cophase power supply converter based on a power electronic technology is mainly adopted to supply single-phase alternating current to an electric locomotive, and meanwhile, negative sequence current can be prevented from being generated in a three-phase power grid. However, the capacity of the existing cophase power supply converter is generally the same as the capacity provided by the traction substation to an alternating current contact network, so that the cost of the converter is high.

Disclosure of Invention

In view of the defects and shortcomings in the prior art, the invention provides the in-phase power supply converter of the traction power supply system of the electrified railway with the converter capacity being half of the power supply capacity and the control method thereof.

In order to solve the technical problems, the invention adopts the following technical scheme: a half-capacity cophase power supply converter is composed of a multi-winding transformer and a three-phase single-phase AC-AC converter. The multi-winding transformer comprises seven windings, one connecting terminal of a first winding is T1, and the other connecting terminal of the first winding is connected to a point N1; one connection terminal of the second winding is T2, and the other connection terminal of the second winding is connected to point N1; one connection terminal of the third winding is T3, and the other connection terminal of the third winding is connected to a point N1; one connection terminal of the fourth winding is T4, and the other connection terminal of the fourth winding is connected to a point N2; one connection terminal of the fifth winding is T5, and the other connection terminal of the fifth winding is connected to point N2; one connection terminal of the sixth winding is T6, and the other connection terminal of the sixth winding is connected to point N2; one connection terminal of the seventh winding is T7, and the other connection terminal of the seventh winding is T8; the three-phase-single-phase AC-AC converter is provided with five connecting terminals Ta, Tb, Tc, Tx and Ty; the winding terminal T1 of the multi-winding transformer is connected to the A phase of the three-phase alternating current power grid, the terminal T2 is connected to the B phase of the three-phase alternating current power grid, and the terminal T3 is connected to the C phase of the three-phase alternating current power grid; t4 is connected to the Ta terminal of the three-phase to single-phase AC-AC converter, T5 is connected to the Tb terminal of the three-phase to single-phase AC-AC converter, T6 is connected to the Tc terminal of the three-phase to single-phase AC-AC converter; the T7 is connected to the Ty terminal of the three-phase-single-phase AC-AC converter, and the T8 is connected to the steel rail; the Tx terminal of the three-phase-single-phase AC-AC converter is connected to an overhead line system.

The winding voltage u of the multi-winding transformer_T4N2And u_T1N1In phase, u_T5N2And u_T2N1In phase, u_T6N2And u_T3N1In phase, u_T7T8And u_T3N1In phase; the winding voltage u of the multi-winding transformer_T4N2、u_T5N2、u_T6N2、u_T7T8And a connection terminal voltage u of the three-phase-single-phase AC-AC converter_TxTyAre all equal in amplitude and are 1/2 of the supply voltage between the catenary and the rail.

The input currents of Ta, Tb and Tc connecting terminals of the three-phase-single-phase AC-AC converter are i respectively_a、i_bAnd i_cThe output current of a seventh winding terminal T7 of the multi-winding transformer winding is i_f(ii) a The electric angle operator lags by 120 DEG is represented by alpha, alpha x represents an instantaneous value lags by 120 DEG in electric angle with respect to the real-time variable x, alpha²x represents a real-time variablex lags by an instantaneous value of 240 ° in electrical angle; i.e. i_a、i_bAnd i_cThe positive sequence component of (a) is obtained as follows: i.e. i_a+＝(i_a+αi_b+α²i_c)/3，i_b+＝(α²i_a+i_b+αi_c)/3，i_c+＝(αi_a+α²i_b+i_c)/3。i_a、i_bAnd i_cThe negative sequence component of (a) is obtained as follows: i.e. i_a-＝(i_a+α²i_b+αi_c)/3，i_b-＝(αi_a+i_b+α²i_c)/3，i_c-＝(α²i_a+αi_b+i_c)/3。

The real-time phase of the sine alternating voltage of the A-phase power grid is theta, the real-time phase of the sine alternating voltage of the B-phase power grid is theta-120 degrees, the real-time phase of the sine alternating voltage of the C-phase power grid is theta-240 degrees, and i_a+、i_b+And i_c+The reactive component of (a) is obtained as follows:

i_a+q＝I_qabc+×cos(θ)，i_b+q＝I_qabc+×cos(θ-120°)，i_c+q＝I_qabc+xcos (. theta. -240 ℃ C.). Wherein the content of the first and second substances,

I_qabc+＝[i_a+×cos(θ)+i_b+×cos(θ-120°)+i_c+×cos(θ-240°)]×2/3。

i_fthe positive sequence component of (a) is obtained as follows: i.e. i_fa+＝α²i_f/3，i_fb+＝αi_f/3，i_fc+＝i_f/3。i_fThe negative sequence component of (a) is obtained as follows: i.e. i_fa-＝αi_f/3，i_fb-＝α²i_f/3，i_fc-＝i_f/3。

i_fa+、i_fb+And i_fc+The reactive component of (a) is obtained as follows:

i_fa+q＝I_qf+×cos(θ)，i_fb+q＝I_qf+×cos(θ-120°)，i_fc+q＝I_qf+xcos (. theta. -240 ℃ C.). Wherein the content of the first and second substances,

I_qf+＝[i_fa+×cos(θ)+i_fb+×cos(θ-120°)+i_fc+×cos(θ-240°)]×2/3。

the three-phase-single-phase AC-AC converter enables the i to be controlled in a closed loop mode_a-、i_b-、i_c-、i_fa-、i_fb-、i_fc-、i_a+q、i_b+q、i_c+q、i_fa+q、i_fb+q、i_fc+qThe following relationship is satisfied:

i_a-+i_fa-＝i_b-+i_fb-＝i_c-+i_fc-＝0，i_a+q+i_fa+q＝i_b+q+i_fb+q＝i_c+q+i_fc+q＝0。

compared with the prior art, the invention has the beneficial effects that: according to the invention, the unit power factor operation of three primary windings of the multi-winding transformer is realized by controlling the input side current of the three-phase-single-phase AC-AC converter, namely, the input current has no reactive current and no negative sequence current, so that the influence of the negative sequence current on an electric locomotive is avoided; the single-phase output side current of the three-phase-single-phase AC-AC converter is the same as the current supplied by the traction substation to the contact network, and the output voltage is half of the voltage of the contact network, so that the capacity of the power electronic device is effectively reduced, the manufacturing cost is reduced, and the input cost is reduced.

Drawings

The invention will be further described with reference to the following drawings and detailed description:

FIG. 1 is a schematic diagram of a half-capacity in-phase power converter circuit of the present invention;

FIG. 2 is a schematic circuit diagram of one embodiment of a three-phase to single-phase AC-AC converter in a half capacity in-phase power converter of the present invention;

fig. 3 is a block diagram of a control strategy for the three-phase to single-phase AC-AC converter of fig. 2.

Detailed Description

For better understanding of the technical solutions and advantages of the present invention, the following detailed description of the present invention is provided in conjunction with the accompanying drawings and specific embodiments, it should be understood that the specific embodiments described herein are only for the understanding of the present invention and are not intended to limit the present invention, and all other embodiments obtained by those of ordinary skill in the art without any inventive work are within the scope of the present invention.

Fig. 1 is a schematic diagram of a half-capacity in-phase power supply converter circuit of the invention, which consists of a multi-winding transformer and a three-phase-single-phase AC-AC converter. The multi-winding transformer comprises seven windings, one connecting terminal of a first winding is T1, and the other connecting terminal of the first winding is connected to a point N1; one connection terminal of the second winding is T2, and the other connection terminal of the second winding is connected to point N1; one connection terminal of the third winding is T3, and the other connection terminal of the third winding is connected to a point N1; one connection terminal of the fourth winding is T4, and the other connection terminal of the fourth winding is connected to a point N2; one connection terminal of the fifth winding is T5, and the other connection terminal of the fifth winding is connected to point N2; one connection terminal of the sixth winding is T6, and the other connection terminal of the sixth winding is connected to point N2; one connection terminal of the seventh winding is T7, and the other connection terminal of the seventh winding is T8; the three-phase-single-phase AC-AC converter is provided with five connecting terminals Ta, Tb, Tc, Tx and Ty; the multi-winding transformer winding terminal T1 is connected to the a-phase of the three-phase ac grid, T2 is connected to the B-phase of the three-phase ac grid, and T3 is connected to the C-phase of the three-phase ac grid; t4 is connected to the Ta terminal of the three-phase to single-phase AC-AC converter, T5 is connected to the Tb terminal of the three-phase to single-phase AC-AC converter, T6 is connected to the Tc terminal of the three-phase to single-phase AC-AC converter; the T7 is connected to the Ty terminal of the three-phase-single-phase AC-AC converter, and the T8 is connected to the steel rail; the Tx terminal of the three-phase-single-phase AC-AC converter is connected to the overhead line system.

Winding voltage u of multi-winding transformer_T4N2And u_T1N1In phase, u_T5N2And u_T2N1In phase, u_T6N2And u_T3N1In phase, u_T7T8And u_T3N1In phase; winding voltage u of multi-winding transformer_T4N2、u_T5N2、u_T6N2、u_T7T8And connection terminal voltage u of three-phase-single-phase AC-AC converter_TxTyAre all equal in amplitude and are 1/2 of the supply voltage between the catenary and the rail.

Input currents of Ta, Tb and Tc connection terminals of a three-phase-single-phase AC-AC converter are i_a、i_bAnd i_cThe output current of the seventh winding terminal T7 of the multi-winding transformer winding is i_f(ii) a The electric angle operator lags by 120 DEG is represented by alpha, alpha x represents an instantaneous value lags by 120 DEG in electric angle with respect to the real-time variable x, alpha²x represents an instantaneous value that lags the real-time variable x by 240 ° in electrical angle; i.e. i_fThe positive sequence component of (a) is obtained as follows: i.e. i_fa+＝α²i_f/3，i_fb+＝αi_f/3，i_fc+＝i_f/3。i_fThe negative sequence component of (a) is obtained as follows: i.e. i_fa-＝αi_f/3，i_fb-＝α²i_f/3，i_fc-＝i_f/3。

The real-time phase of the sine alternating voltage of the A-phase power grid is theta, the real-time phase of the sine alternating voltage of the B-phase power grid is theta-120 degrees, the real-time phase of the sine alternating voltage of the C-phase power grid is theta-240 degrees, and i_fa+、i_fb+And i_fc+The reactive component of (a) is obtained as follows:

i_fa+q＝I_qf+×cos(θ)，i_fb+q＝I_qf+×cos(θ-120°)，i_fc+q＝I_qf+xcos (. theta. -240 ℃ C.). Wherein, I_qf+＝[i_fa+×cos(θ)+i_fb+×cos(θ-120°)+i_fc+×cos(θ-240°)]×2/3。

Fig. 2 is a schematic circuit diagram of a specific embodiment of a three-phase to single-phase AC-AC converter in a half-capacity in-phase power supply converter according to the present invention, and the converter is composed of 6N power modules PM, where N is a positive integer, and the power modules PM can be selected from half-bridge and full-bridge circuits. The terminals Ta, Tb, Tc, Tx and Ty of the three-phase-single-phase AC converter and the positive pole P are respectively connected with N power modules PM and an inductor L in series; the terminals Ta, Tb, Tc, Tx and Ty of the three-phase-single-phase AC converter and the negative pole N are respectively connected with N power modules PM and an inductor L in series.

FIG. 3 is a three-phase-single-phase diagram of FIG. 2Control strategy block diagram of AC-AC converter, and outer ring reference value u of direct-current voltage_{PN_ref}And a DC voltage feedback value u_PNGenerating the amplitude I of the reference value of the current inner loop positive sequence active current through the PI regulator by taking the difference_+p。I_+pMultiplying by sin (theta), sin (theta-120 degrees) and sin (theta +120 degrees) respectively to obtain a three-phase positive sequence active current reference value i_{a+p_ref}、i_{b+p_ref}、i_{c+p_ref}。

i_{a+p_ref}-i_fa--i_fa+q＝i_{a_ref}，i_{a_ref}And i_aAfter the difference is made, pass through PR adjuster and subtract u_T4N2Then as u_{a_ref}，u_PN/2-u_{a_ref}As the PM reference voltage between Ta and P, u_PN/2+u_{a_ref}As the PM reference voltage between Ta and N; i.e. i_{b+p_ref}-i_fb--i_fb+q＝i_{b_ref}，i_{b_ref}And i_bAfter the difference is made, pass through PR adjuster and subtract u_T5N2Then as u_{b_ref}，u_PN/2-u_{b_ref}As PM reference voltage between Tb and P, u_PN/2+u_{b_ref}As the PM reference voltage between Tb and N; i.e. i_{c+p_ref}-i_fc--i_fc+q＝i_{c_ref}，i_{c_ref}And i_cAfter the difference is made, pass through PR adjuster and subtract u_T6N2Then as u_{c_ref}，u_PN/2-u_{c_ref}As the PM reference voltage between Tc and P, u_PN/2+u_{c_ref}As the PM reference voltage between Tc and N.

u_{TxTy_ref}1/2 for supplying voltage between contact net and rail, i.e. u_{TxTy_ref}＝u_TxT8/2。u_PN/2-u_{TxTy_ref}V 2 as reference voltages for PM between Tx and P and PM between Ty and N, u_PN/2+u_{TxTy_ref}And/2 as the reference voltage for PM between Tx and N and PM between Ty and P.

In summary, the primary winding of the multi-winding transformer includes seven windings, three windings of the primary winding of the multi-winding transformer are connected to the three-phase AC power grid, three secondary windings of the multi-winding transformer are connected to the input side of the three-phase-single-phase AC-AC converter, and the output side of the three-phase-single-phase AC-AC converter and the fourth winding of the multi-winding transformer are connected in series and then connected to the traction contact system of the electrified railway and the steel rail. The unit power factor operation of three primary windings of the multi-winding transformer is realized by controlling the input side current of the three-phase-single-phase AC-AC converter, namely, the input current has no reactive current and has no negative sequence current. The single-phase output side current of the three-phase-single-phase AC-AC converter is the same as the current supplied by the traction substation to the contact network, and the sum of the output voltage and the voltage of the contact network is half of the voltage of the contact network, so that the capacity and the manufacturing cost of the power electronic device can be reduced.