A combined same-phase power supply structure and compensation method thereof

Abstract

The present invention discloses a combined co-phase power supply structure and a compensation method thereof, wherein the co-phase power supply structure comprises a first traction transformer, a second traction transformer, a three-phase compensation transformer and a co-phase compensation device; the primary sides of the first traction transformer and the second traction transformer are single-phase windings connected to the three-phase high-voltage bus, and the secondary sides respectively comprise traction windings and compensation windings connected to the traction bus; the primary side of the three-phase compensation transformer is connected to the three-phase high-voltage bus, and the secondary side is connected to the input end of the co-phase compensation device; the compensation windings of the secondary sides of the first traction transformer and the second traction transformer are connected in pairs to form a compensation bus; the compensation bus is respectively connected to the output end of the co-phase compensation device. Therefore, the present invention can not only effectively realize co-phase traction power supply and eliminate electrical phase separation, but also has a compensation winding that minimizes the capacity of the co-phase compensation device, effectively eliminating the problem of voltage imbalance.

Description

Technical Field

[0001] The present invention relates to the field of electrified railway traction power supply, and in particular to a combined same-phase power supply and transformation structure of a single-phase multi-winding transformer and a three-phase transformer and a compensation method thereof. Background Art

[0002] my country's electrified railways generally adopt single-phase industrial frequency AC system. In order to make the single-phase traction load as balanced as possible in the three-phase power system, electrified railways often adopt the scheme of rotating phase sequence and phase-divided power supply. Phase-divided insulators are set in the adjacent power supply sections at the phase-divided and divided places, which is called electrical phase separation or phase separation. In order to prevent the electric locomotive from burning arcs and burning the contact network suspension components when it is energized through the electrical phase separation, and even causing accidents such as phase-to-phase short circuit, and with the continuous increase of train speed, when the driver cannot manually degrade, turn off the auxiliary unit, cut off the main circuit breaker, rely on the inertia of the train to pass through the neutral section, close the main circuit breaker, close the auxiliary unit, and upgrade to restore the traction power to complete the phase separation, the existing traction power supply system has introduced automatic phase separation technology, mainly including ground switch automatic phase separation, vehicle-mounted automatic phase separation, and pole-mounted automatic phase separation. However, there is still a transient electrical process when the train passes through the electrical phase separation during the switch switching, which is easy to produce large operating overvoltage or overcurrent, causing accidents such as burning of the traction network and vehicle-mounted equipment, affecting the power supply reliability and safe operation of the train. Therefore, the electrical phase separation link is the weakest link in the entire traction power supply system, and excessive phase separation of trains has become a bottleneck in the traction power supply of high-speed railways and even the entire electrified railways.

[0003] High-speed and heavy-load railways have widely adopted high-power AC-DC-AC electric locomotives or EMUs based on IGBT fully controllable devices. The core of these locomotives is a traction converter with multiple four-quadrant PWM control and multiple control. In actual operation, the harmonic content is small and the power factor is close to 1. However, the traction power of AC-DC-AC electric locomotives or EMUs is large. For example, the rated power of a single-car high-speed EMU running in large formations is as high as 25MW (equivalent to 5 trains on conventional railways). These large-scale high-power single-phase loads have caused increasingly serious power quality problems on the three-phase power grid, mainly the three-phase voltage imbalance (negative sequence), which cannot be ignored.

[0004] Theory and practice have shown that the use of co-phase power supply technology can not only eliminate the electrical phase separation at the traction substation outlet and eliminate the power supply bottleneck, but also effectively control the negative sequence current and achieve the power quality requirements based on the three-phase voltage imbalance (negative sequence) limit, which is conducive to promoting the harmonious development of electricity and railways. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a combined same-phase power supply structure and a compensation method thereof, which can not only effectively realize the same-phase traction power supply of the electrified railway and eliminate the electrical phase separation at the substation outlet, but also effectively eliminate the voltage imbalance problem of the three-phase system caused by the single-phase load of the electrified railway. At the same time, the relevant windings are highly integrated, occupy less space and are easy to install.

[0006] In view of this, the present invention adopts the following technical solution:

[0007] A combined co-phase power supply structure, which includes a first traction transformer, a second traction transformer serving as a backup for the first traction transformer, a three-phase compensation transformer and a co-phase compensation device; the primary sides of the first traction transformer and the second traction transformer are single-phase windings connected to the three-phase high-voltage bus, and the secondary sides respectively include traction windings and compensation windings connected to the traction bus; the primary side of the three-phase compensation transformer is connected to the three-phase high-voltage bus, and a phase lead-out port of the secondary side is connected to the input end of the co-phase compensation device; the compensation windings of the secondary sides of the first traction transformer and the second traction transformer are connected in parallel in pairs to form a compensation bus; the compensation bus is correspondingly connected to the output end of the co-phase compensation device.

[0008] Preferably, a plurality of the same-phase compensation devices are provided, and the parallel port of the input end of each same-phase compensation device is connected to a phase lead-out port of the secondary side of the three-phase compensation transformer, and each same-phase compensation device is connected in parallel with each other; or the series port of the input end of each same-phase compensation device is connected to the secondary side of the three-phase compensation transformer.

[0009] Further preferably, the traction winding and compensation winding port voltages of the first traction transformer and the second traction transformer are in phase, and are both in phase with the voltage of one line in the three-phase high-voltage bus.

[0010] Further preferably, the voltage at one-phase lead-out port of the secondary side of the three-phase compensation transformer is in phase with the voltage of one phase in the three-phase high-voltage bus, and is perpendicular to the voltage phase of the traction winding or compensation winding of the first traction transformer and the second traction transformer.

[0011] Preferably, the number of compensation windings on the secondary side of the first traction transformer, the number of compensation windings on the secondary side of the second traction transformer, the number of in-phase compensation devices and the number of compensation busbars are all equal.

[0012] Further preferably, the capacity of each compensation winding of the first traction transformer or the second traction transformer is not greater than the capacity of the traction winding of the first traction transformer or the second traction transformer.

[0013] Preferably, the in-phase compensation device may adopt an H-bridge cascade or a low-voltage H-bridge in a back-to-back structure.

[0014] Preferably, the three-phase compensation transformer can adopt YNd11 connection.

[0015] In view of this, the present invention adopts the following technical solution:

[0016] A compensation method using the above-mentioned combined co-phase power supply structure, wherein the specific steps of the compensation method include the following:

[0017] When the traction winding of the first traction transformer or the second traction transformer supplies traction power, the compensation winding outputs a negative compensation load to the output end of the same-phase compensation device connected thereto, and the secondary lead-out port of the three-phase compensation transformer outputs a positive compensation load to the input end of the same-phase compensation device connected thereto, and the value of the negative compensation load is equal to the value of the positive compensation load;

[0018] When the traction winding of the first traction transformer or the second traction transformer supplies regenerative power, the compensation winding outputs a positive compensation load to the output end of the same-phase compensation device to which it is connected, and the secondary lead-out port of the three-phase compensation transformer outputs a negative compensation load to the input end of the same-phase compensation device to which it is connected, and the value of the positive compensation load is equal to the value of the negative compensation load.

[0019] Preferably, during normal operation, the first traction transformer, the same-phase compensation device and the three-phase compensation transformer are working, and the second traction transformer is not working; when the first traction transformer exits, the second traction transformer is put into operation.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention can improve the flexibility and reliability of the operation of the traction substation. When the three-phase compensation transformer or the same-phase compensation device is out of operation, the first traction transformer can continue to work alone. When the first traction transformer is out of operation, the second traction transformer is put into operation. The compensation branch circuit is appropriately increased in redundancy, and the withdrawal of a single same-phase compensation device does not affect the normal operation of the system;

[0022] 2. Compared with the traditional same-phase power supply and transformation structure, the present invention eliminates the matching transformer on the traction network side, and its function is replaced by the compensation winding of the first traction transformer, which can save the equipment floor space of the traction station and reduce the number of equipment installations and maintenance;

[0023] 3. The three-phase compensating transformer of the present invention adopts the YNd11 standard wiring, which is easy to manufacture. At the same time, the primary side can implement high current grounding, and the secondary three-phase winding can also provide three-phase symmetrical power;

[0024] 4. The present invention adopts a same-phase compensation device to generate equal negative-sequence power with the same direction in the compensation winding and the three-phase compensation transformer. The negative-sequence power is opposite to the traction load power in the traction winding of the first traction transformer or the second traction transformer, thereby effectively eliminating the voltage imbalance problem of the three-phase system caused by the single-phase load of the electrified railway. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the combined in-phase power supply structure described in Example 1 of the present invention.

[0026] Figure 2 It is a specific structural schematic diagram of the combined in-phase power supply structure described in Example 1 of the present invention.

[0027] Figure 3 It is a structural schematic diagram of the combined in-phase power supply structure described in the second embodiment of the present invention.

[0028] Figure 4 It is a specific structural diagram of the combined in-phase power supply structure described in the second embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to better understand the creative idea of ​​the present invention, the working principle of the present invention is described as follows:

[0030] The compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c The same-phase compensation device CPD and the three-phase compensation transformer CPT together form a compensation branch. The same-phase compensation device CPD is in the compensation winding W c The same amount of negative sequence power with the same direction is generated in the three-phase compensation transformer CPT, and the negative sequence power is connected to the traction winding W of the first traction transformer TT1 or the second traction transformer TT2. t The power direction of the traction load in the circuit is opposite. Reasonable design and control of the power capacity of the compensation branch can limit the three-phase voltage imbalance caused by the residual negative sequence current of the traction load to within the national standard range, and the three-phase voltage imbalance meets the national standard requirements.

[0031] Embodiment 1

[0032] like Figure 1 As shown, an embodiment of the present invention provides a combined in-phase power supply structure, which includes a first traction transformer TT1, a second traction transformer TT2 that is a backup for the first traction transformer TT1, a three-phase compensation transformer CPT and n in-phase compensation devices CPD, where n is a positive integer; the primary sides of the first traction transformer TT1 and the second traction transformer TT2 are single-phase windings connected to the three-phase high-voltage bus, and the secondary sides respectively include traction windings W connected to the traction bus BT.t and n compensation windings W c The primary side of the three-phase compensation transformer CPT is connected to the A phase, B phase, and C phase of the three-phase high-voltage bus, and the secondary side of the one-phase lead-out port is connected to the input end of each in-phase compensation device CPD; the compensation winding W of the secondary side of the first traction transformer TT1 and the second traction transformer TT2 c Two by two are connected in parallel to form n compensation busbars B c Each compensation bus B c They are respectively connected to the output ends of each common-phase compensation device CPD in a one-to-one correspondence.

[0033] In the embodiment of the present invention, the traction winding W of the first traction transformer TT1 and the second traction transformer TT2 t One end is connected to the traction bus BT, and the traction winding W of the first traction transformer TT1 and the second traction transformer TT2 t The other end is grounded. c and the compensation winding W of the second traction transformer TT2 c Connected to each other to form n compensation busbars B c .

[0034] The traction winding W of the first traction transformer TT1 and the second traction transformer TT2 t And compensation winding W c The port voltages are in phase and are in phase with the voltage of one line in the three-phase high-voltage bus. The phase of the voltage of the secondary one-phase lead-out port of the three-phase compensation transformer CPT is the same as the traction winding W of the first traction transformer TT1 and the second traction transformer TT2. t and compensation winding W c The voltage phase is vertical.

[0035] The secondary compensation winding W of the first traction transformer TT1 c The number of the secondary compensation winding W of the second traction transformer TT2 c The number of in-phase compensation devices CPD and the compensation bus B c Each compensation winding W of the first traction transformer TT1 or the second traction transformer TT2 is equal. c The capacity is not greater than the traction winding W t capacity.

[0036] In the embodiment of the present invention, each in-phase compensation device CPD can adopt a back-to-back H-bridge cascade or a low-voltage H-bridge. The three-phase compensation transformer CPT can adopt a three-phase standard connection of YNd11.

[0037] like Figure 2As shown, in order to better understand the technical solution described in the embodiment of the present invention, the H-bridge cascade of the same-phase compensation device CPD with a back-to-back structure and the YNd11 connection of the three-phase compensation transformer CPT are taken as an example to specifically illustrate: the combined same-phase power supply and transformation structure includes a first traction transformer TT1, a three-phase compensation transformer CPT, one or more back-to-back same-phase compensation devices CPD and a second traction transformer TT2; the primary sides of the first traction transformer TT1, the three-phase compensation transformer CPT and the second traction transformer TT2 are connected to the three-phase high-voltage bus, and the phases of the three-phase high-voltage bus are marked as A, B, and C; the secondary sides of the first traction transformer TT1 and the second traction transformer TT2 are respectively connected by a traction winding W t and multiple compensation windings W c The traction winding W of the first traction transformer TT1 and the second traction transformer TT2 is composed of t Connect the traction bus BT, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 respectively. c The number is equal, two by two are connected in parallel to form multiple compensation busbars B c , each compensation bus B c They are respectively connected to the output end of the corresponding in-phase compensation device CPD; the input end of each in-phase compensation device CPD is connected to the secondary one-phase lead-out port of the three-phase compensation transformer CPT.

[0038] In the embodiment of the present invention, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c The number and the number of co-phase compensation devices CPD can be appropriately increased with redundant backup according to project needs, so that when one of the co-phase compensation devices CPD stops running, it can continue to work.

[0039] In addition, all compensation windings W of the first traction transformer TT1 and the second traction transformer TT2 c With its traction winding W t The corresponding port voltages are the same, and the phases of the line voltage of the corresponding three-phase system and the output phase voltage of the one-phase lead-out port of the secondary side of the three-phase compensation transformer CPD are perpendicular to each other; the output power of the AC output port of each in-phase compensation device CPD is equal to the input power of its AC input port, and the phase difference between the two is also 90°; the in-phase compensation device CPD has a phase difference of 90° in all compensation windings W cThe negative sequence generated by the secondary winding of the three-phase compensation transformer CPT is equal in size and phase, and opposite in phase to the negative sequence generated by the traction load, thus realizing negative sequence compensation. The three-phase compensation transformer CPT adopts the three-phase standard wiring topology of YNd11. The primary side provides a large current grounding point, and the power capacity of the secondary three-phase winding is set as one heavy and two light as required. The secondary heavy winding is connected to the parallel connection port of all the same-phase compensation devices CPD connected in parallel with each other, and its power capacity and voltage size match the power capacity and port voltage of the same-phase compensation device CPD.

[0040] In the embodiment of the present invention, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c , the same-phase compensation device CPD and the three-phase compensation transformer CPT together constitute the compensation branch; reasonable design and control of the power capacity of the compensation branch can limit the three-phase voltage imbalance caused by the residual negative sequence current of the traction load to within the national standard range, and the three-phase voltage imbalance meets the national standard requirements.

[0041] Embodiment 2

[0042] like Figure 3 As shown, an embodiment of the present invention provides a combined in-phase power supply structure, which includes a first traction transformer TT1, a second traction transformer TT2 that is a backup for the first traction transformer TT1, a three-phase compensation transformer CPT and n in-phase compensation devices CPD, where n is a positive integer; the primary sides of the first traction transformer TT1 and the second traction transformer TT2 are single-phase windings connected to the three-phase high-voltage bus, and the secondary sides respectively include traction windings W connected to the traction bus BT. t and n compensation windings W c The primary side of the three-phase compensation transformer CPT is connected to the A phase, B phase, and C phase of the three-phase high-voltage bus, and the secondary side is connected to the input end of each in-phase compensation device CPD; the compensation winding W of the secondary side of the first traction transformer TT1 and the second traction transformer TT2 c Two by two are connected in parallel to form n compensation busbars B c The n compensation busbars B c They are respectively connected to the output ends of n common-phase compensation devices CPD in a one-to-one correspondence.

[0043] In the embodiment of the present invention, the traction winding W of the first traction transformer TT1 and the second traction transformer TT2 t One end is connected to the traction bus BT, and the compensation winding W of the first traction transformer TT1 c One end and the compensation winding W of the second traction transformer TT2 c Connected to each other to form n compensation busbars B cIn the embodiment of the present invention, in order to improve the reliability of the same-phase power supply, a switch K is connected in parallel between the input ends of the adjacent same-phase compensation devices CPD, so that the redundancy backup can be appropriately increased or decreased according to the working conditions and the normal operation of the system is not affected when a single same-phase compensation device stops operating.

[0044] The traction winding W of the first traction transformer TT1 and the second traction transformer TT2 t And compensation winding W c The port voltages are in phase and are in phase with the voltage of one line in the three-phase high-voltage bus. The voltage phase of the secondary one-phase lead-out port of the three-phase compensation transformer CPT is the same as the traction winding W of the first traction transformer TT1 and the second traction transformer TT2. t Or compensation winding W c The voltage phase is vertical.

[0045] The secondary compensation winding W of the first traction transformer TT1 c The number of the secondary compensation winding W of the second traction transformer TT2 c The number of in-phase compensation devices CPD and the compensation bus B c Each compensation winding W of the first traction transformer TT1 or the second traction transformer TT2 is equal. c The capacity is not greater than the traction winding W t capacity.

[0046] In the embodiment of the present invention, each in-phase compensation device CPD can adopt a back-to-back H-bridge cascade or a low-voltage H-bridge. The three-phase compensation transformer CPT can adopt a three-phase standard connection of YNd11.

[0047] like Figure 4 As shown, in order to better understand the technical solution described in the embodiment of the present invention, the H-bridge cascade of the same-phase compensation device CPD with a back-to-back structure and the YNd11 connection of the three-phase compensation transformer CPT are taken as an example to specifically illustrate: the combined same-phase power supply and transformation structure includes a first traction transformer TT1, a three-phase compensation transformer CPT, n back-to-back same-phase compensation devices CPD and a second traction transformer TT2; the primary sides of the first traction transformer TT1, the three-phase compensation transformer CPT and the second traction transformer TT2 are connected to the three-phase high-voltage bus, and the phases of the three-phase high-voltage bus are marked as A, B, and C; the secondary sides of the first traction transformer TT1 and the second traction transformer TT2 are respectively composed of a traction winding W t and n compensation windings W c The traction winding W of the first traction transformer TT1 and the second traction transformer TT2 is composed of tConnect the traction bus BT, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 respectively. c The number is equal, two by two are connected in parallel to form n compensation busbars B c , each compensation bus B c They are respectively connected to the output end of the corresponding in-phase compensation device CPD; the input end of each in-phase compensation device CPD is connected to the secondary one-phase lead-out port of the three-phase compensation transformer CPT.

[0048] In the embodiment of the present invention, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c The number and the number of co-phase compensation devices CPD can be appropriately increased with redundant backup according to project needs, so that when one of the co-phase compensation devices CPD stops running, it can continue to work.

[0049] In addition, all compensation windings W of the first traction transformer TT1 and the second traction transformer TT2 c With its traction winding W t The polarity of the corresponding ends is the same, and the phase quantities of the line voltage of the corresponding three-phase system and the output phase voltage of the secondary winding of the three-phase compensation transformer CPD are perpendicular; the output power of the AC output end of each in-phase compensation device CPD is equal to the input power of its AC input end, and the phase difference between the two is also 90°; the in-phase compensation device CPD has a phase difference of 90° in all compensation windings W c The negative sequence generated by the secondary winding of the three-phase compensation transformer CPT is equal in size and phase, and opposite in phase to the negative sequence generated by the traction load, thus realizing negative sequence compensation. The three-phase compensation transformer CPT adopts the three-phase standard wiring topology of YNd11. The primary side provides a large current grounding point, and the power capacity of the secondary three-phase winding is set as one heavy and two light as required. The secondary heavy winding is connected to the series port of all the same-phase compensation devices CPD, and its power capacity and voltage size match the power capacity and port voltage of the same-phase compensation device CPD.

[0050] In the embodiment of the present invention, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c , the same-phase compensation device CPD and the three-phase compensation transformer CPT together constitute the compensation branch; reasonable design and control of the power capacity of the compensation branch can limit the three-phase voltage imbalance caused by the residual negative sequence current of the traction load to within the national standard range, and the three-phase voltage imbalance meets the national standard requirements.

[0051] Embodiment 3

[0052] The embodiment of the present invention provides a compensation method using the above-mentioned combined co-phase power supply structure. When working normally, the first traction transformer TT1, the co-phase compensation device CPD and the three-phase compensation transformer CPT work, and the second traction transformer TT2 does not work; or when the first traction transformer TT1 is out of service, the second traction transformer TT2 is put into operation; the specific steps of the compensation method include the following:

[0053] When the traction winding W of the first traction transformer TT1 or the second traction transformer TT2 t When supplying traction power, the compensation winding W c Outputting a negative compensation load to the output terminal of the connected same-phase compensation device CPD, and outputting a positive compensation load to the input terminal of the connected same-phase compensation device CPD by a phase lead-out port of the secondary side of the three-phase compensation transformer CPT, wherein the value of the negative compensation load is equal to the value of the positive compensation load;

[0054] When the traction winding W of the first traction transformer TT1 or the second traction transformer TT2 t When supplying regenerative power, the compensation winding W c A positive compensation load is output to the output terminal of the connected same-phase compensation device CPD, and a one-phase lead-out port of the secondary side of the three-phase compensation transformer CPT outputs a negative compensation load to the input terminal of the connected same-phase compensation device CPD, and the value of the positive compensation load is equal to the value of the negative compensation load.

[0055] In the embodiment of the present invention, when the co-phase compensation device CPD and the three-phase compensation transformer CPT are out of operation, the first traction transformer TT1 works alone, and the second traction transformer TT2 can also replace the first traction transformer TT1 to work alone. In this case, the combined co-phase power supply and transformation structure cannot perform the compensation method described in the embodiment of the present invention, and only supplies traction power. However, it is conducive to improving the flexibility and reliability of the operation of the traction substation.

[0056] In the embodiment of the present invention, all the compensation windings W of the first traction transformer TT1 and the second traction transformer TT2 c With its traction winding W t The polarity of the corresponding ends is the same, and the phase between the line voltage of the corresponding three-phase system and the output phase voltage of the one-phase lead-out port of the secondary side of the three-phase compensation transformer CPD is perpendicular; the output power of one AC port of all in-phase compensation devices CPD is equal to the input power of the other AC port, and the phase difference between the two is also 90°; the in-phase compensation device CPD has all compensation windings W cThe negative sequence generated by the secondary lead-out port of the three-phase compensation transformer CPT is equal in size and phase, and opposite in phase to the negative sequence generated by the traction load, thus realizing negative sequence compensation. The three-phase compensation transformer CPT adopts the three-phase standard wiring topology of YNd11. The primary side provides a large current grounding point, and the power capacity of the three-phase winding on the secondary side is set to one heavy and two light as required. The secondary heavy winding is connected to the parallel ports of all the same-phase compensation devices CPD connected in parallel with each other or to the series ports of all the same-phase compensation devices CPD. Its power capacity and voltage size match the power capacity and port voltage of the same-phase compensation device CPD.

[0057] All compensation windings W of the first traction transformer TT1 and the second traction transformer TT2 c , each co-phase compensation device CPD and the three-phase compensation transformer CPT together constitute a compensation branch; when working normally, the power of the traction load is jointly provided by the primary winding of the first traction transformer TT1 and the compensation branch; when the power of the traction load is equal to or less than twice the power capacity of the compensation branch, the primary winding of the first traction transformer TT1 and the compensation branch each provide 1 / 2 of the power of the traction load, at this time the negative sequence current caused by the traction load is fully compensated; when the power of the traction load is greater than twice the power capacity of the compensation branch, the compensation branch works at full load, at this time there is residual negative sequence current in the three-phase power grid; reasonable design of the power capacity of the compensation branch can limit the three-phase voltage imbalance caused by the residual negative sequence current of the traction load to within the national standard range, and the three-phase voltage imbalance meets the national standard requirements.

[0058] In addition, the compensation winding W of the first traction transformer TT1 and the second traction transformer TT2 c The number and the number of co-phase compensation devices CPD can be appropriately increased with redundant backup according to project needs, so that when one of the co-phase compensation devices CPD stops running, it can continue to work.

[0059] In summary, the co-phase power supply and transformation structure and its compensation method described in the present invention are based on a single-phase multi-winding traction transformer and a three-phase compensation transformer, and are equipped with a co-phase compensation device (AC-DC-AC compensation device) of appropriate capacity, so as to achieve the purpose of eliminating the electrical phase separation at the outlet of the traction substation to eliminate the power supply bottleneck, and to control the negative sequence, meet the power quality requirements of the three-phase voltage imbalance (negative sequence) limit, and achieve a good match between the traction substation wiring method and the power supply device capacity. In addition, the present invention can also improve the system flexibility and reliability, reduce the installation area of ​​the traction station equipment, and reduce the number of equipment installation and maintenance. At the same time, the three-phase compensation transformer with YNd11 structure provides a large current grounding point for the three-phase high-voltage side.

Claims

1. A combined same-phase power supply structure, characterized in that: The invention comprises a first traction transformer (TT1), a second traction transformer (TT2) which is a backup for the first traction transformer (TT1), a three-phase compensation transformer (CPT) and a co-phase compensation device (CPD); the primary sides of the first traction transformer (TT1) and the second traction transformer (TT2) are single-phase windings connected to a three-phase high-voltage bus, and the secondary sides respectively include traction windings (W) connected to a traction bus (BT). t ) and compensation winding (W c ); the primary side of the three-phase compensation transformer (CPT) is connected to the three-phase high-voltage bus, and the secondary side one-phase lead-out port is connected to the input end of the same-phase compensation device (CPD); the compensation windings (W c ) are connected in pairs to form a compensation bus (B c ); the compensation bus (B c ) is connected correspondingly to the output terminal of the common-phase compensation device (CPD); The co-phase compensation device (CPD) generates equal amount of negative sequence power with the same direction in the compensation winding (Wc) and the three-phase compensation transformer (CPT), and the negative sequence power is opposite in direction to the traction load power in the traction winding (Wt) of the first traction transformer (TT1) or the second traction transformer (TT2).

2. The combined in-phase power supply structure according to claim 1, characterized in that: The same-phase compensation device (CPD) is arranged in plurality, and the parallel port of the input end of each same-phase compensation device (CPD) is connected to the secondary-side one-phase lead-out port of the three-phase compensation transformer (CPT), and each same-phase compensation device (CPD) is connected in parallel with each other; or the series port of the input end of each same-phase compensation device (CPD) is connected to the secondary-side one-phase lead-out port of the three-phase compensation transformer (CPT).

3. The combined in-phase power supply structure according to claim 2, characterized in that: The port voltages of the traction winding (Wt) and the compensation winding (Wc) of the first traction transformer (TT1) and the second traction transformer (TT2) are in phase, and are both in phase with the voltage of one line in the three-phase high-voltage bus.

4. The combined in-phase power supply structure according to claim 2, characterized in that: The voltage phase of the one-phase lead-out port of the secondary side of the three-phase compensating transformer (CPT) is perpendicular to the voltage phase of the traction winding (Wt) or the compensation winding (Wc) of the first traction transformer (TT1) and the second traction transformer (TT2).

5. The combined in-phase power supply structure according to claim 1, characterized in that: The number of compensation windings (Wc) on the secondary side of the first traction transformer (TT1), the number of compensation windings (Wc) on the secondary side of the second traction transformer (TT2), the number of co-phase compensation devices (CPD) and the number of compensation busbars (Bc) are all equal.

6. The combined in-phase power supply structure according to claim 4, characterized in that: The capacity of each compensation winding (Wc) of the first traction transformer (TT1) or the second traction transformer (TT2) is not greater than the capacity of the traction winding (Wt) of the first traction transformer (TT1) or the second traction transformer (TT2).

7. The combined in-phase power supply structure according to claim 1, characterized in that: The common-phase compensation device (CPD) may adopt a back-to-back H-bridge cascade or a low-voltage H-bridge.

8. The combined in-phase power supply structure according to claim 1, characterized in that: The three-phase compensating transformer (CPT) can adopt YNd11 connection.

9. A compensation method using the combined co-phase power supply structure according to any one of claims 1 to 8, characterized in that: The specific steps of the compensation method include the following: When the traction winding (Wt) of the first traction transformer (TT1) or the second traction transformer (TT2) supplies traction power, the compensation winding (Wc) outputs a negative compensation load to the output end of the same-phase compensation device (CPD) connected thereto, and the secondary one-phase lead-out port of the three-phase compensation transformer (CPT) outputs a positive compensation load to the input end of the same-phase compensation device (CPD) connected thereto, and the value of the negative compensation load is equal to the value of the positive compensation load; When the traction winding (Wt) of the first traction transformer (TT1) or the second traction transformer (TT2) supplies regenerative power, the compensation winding (Wc) outputs a positive compensation load to the output end of the same-phase compensation device (CPD) to which it is connected, and the one-phase lead-out port of the secondary side of the three-phase compensation transformer (CPT) outputs a negative compensation load to the input end of the same-phase compensation device (CPD) to which it is connected, and the value of the positive compensation load is equal to the value of the negative compensation load.

10. The combined in-phase power supply structure according to claim 9, characterized in that: During normal operation, the first traction transformer (TT1), the co-phase compensation device (CPD) and the three-phase compensation transformer (CPT) are working, and the second traction transformer (TT2) is not working; when the first traction transformer (TT1) exits, the second traction transformer (TT2) starts working.

Images