Hybrid cut-through power supply system for electrified railway and power flow regulation and control method

Abstract

The invention relates to an electrified railway hybrid cut-through power supply system and a power flow regulation and control method, which are used for in-phase cut-through power supply and power flow regulation and control of an electrified railway, the cut-through power supply system is provided with at least two traction substations, and the traction substations comprise transformer type traction substations and AC-DC-AC type traction substations which are alternately arranged. And the ride-through power of the traction network between the transformer type traction substation and the AC-DC-AC type traction substation is 0 through power flow regulation and control. The method is excellent in performance, advanced in technology, reliable and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of AC electrified railway power supply, and in particular to a through power supply system and a power flow control method. Background Art

[0002] The mainline single-phase industrial frequency AC electrified railway is powered by the public power grid. In order to make the single-phase traction load as balanced as possible in the three-phase power system, the electrified railway often adopts the scheme of rotating phase sequence and phase-divided power supply. The adjacent power supply areas at the phase-divided zone are isolated by phase-divided insulators, which is called electrical phase separation, or simply phase separation. The insulator belongs to the neutral section, which is a section without electricity under normal circumstances. The traditional way for electric locomotives to pass through electrical phase separation is manual operation, relying on the driver to manually degrade, turn off the auxiliary unit, disconnect the main circuit breaker, rely on the inertia of the train to pass the neutral section, then close the main circuit breaker, close the auxiliary unit, and then restore the traction power to complete the phase separation. Once this manual phase separation method is misoperated, it is easy to cause the electric locomotive to pass through the electrical phase separation (over-phase) with power on, arcing and burn out the contact network suspension components, and even cause phase-to-phase short circuits and other tripping and power outage accidents. As train speeds continue to increase, automatic over-phase technology has been adopted, mainly including ground switch automatic over-phase switching, on-board automatic over-phase switching, and pole-mounted automatic over-phase switching. However, there is still a transient electrical process when the train passes through the electrical over-phase switching during the switch switching, which is prone to generate large operating overvoltage or overcurrent, causing accidents such as burning of the traction network and on-board equipment, and even leading to failure of automatic over-phase operation, affecting power supply reliability and safe operation of the train. Therefore, the electrical over-phase link is the weakest link in the entire traction power supply system, and the train over-phase switching has become a bottleneck for the traction power supply of high-speed railways and even the entire electrified railway.

[0003] Theory and practice show that the use of single-phase traction transformers or combined same-phase power supply technology in traction substations can eliminate the phase separation at the outlet, and the use of bilateral power supply technology in substations can eliminate the phase separation at the outlet, thereby eliminating the power supply bottleneck and improving the railway power supply capacity and transportation capacity. However, it is worth noting that the bilateral power supply of electrified railway substations is similar to the closed loop of the power grid, and its application is restricted by the conditions of the power grid. For example, the voltage level of the power grid and the traction network is relatively close, the through power (balanced current) is large, and it is not suitable to implement bilateral power supply (closed loop). In this regard, people have proposed a technical solution that has a certain "isolation" and "conversion" effect on the power grid and implements through-power supply for the railway traction network, that is, a traction substation composed of a transformer and an AC-DC-AC converter in series (called an AC-DC-AC type traction substation) to realize through-power supply. Since the AC-DC-AC converter has a DC link, it has the function of isolating the primary AC power grid and the secondary traction power supply system from each other. It can be considered that when the traction power supply system is unloaded, the power flow of the power grid will no longer pass through the traction network, and will not increase the through power in the traction network, nor will it affect the power grid. It is a through-power supply method for electrified railways that the power grid can accept. However, compared with the current method of using traction transformers in traction substations, this method requires the addition of full-power AC-DC-AC converters, which greatly increases the cost, which may reach more than ten times or even dozens of times the original cost, and the cost performance ratio is greatly reduced, which hinders the promotion and application of this method. To this end, a hybrid through-power supply system is proposed. On one line, in the same power grid, under the same technical indicators without increasing the through power, the amount of AC, DC, and AC traction substations used is reduced by more than half, thereby greatly improving the cost performance and the promotion value. At the same time, compared with the traditional converter droop curve control method, the power flow control method of the present invention is more sensitive, more accurate, and has a wider range of applications. It can control the power flow of AC, DC, and AC traction substations without obtaining the train distribution in the system (which cannot be obtained in real time) and the total load, and is not affected by the position and number of trains and their operating conditions (traction or braking), nor is it affected by other (if any) AC, DC, and AC traction substation control methods in the system. Summary of the invention

[0004] The purpose of the present invention is to provide a hybrid through-power supply system for electrified railways, which reduces the number of expensive AC, DC, and AC traction substations by more than half, has the function of blocking the through power path and not generating through power. At the same time, a power flow control method is proposed, which can complete power flow control without obtaining (and being unable to obtain) the distribution position and number of trains in the system and their operating conditions (traction or braking), and is not affected by other (if any) AC, DC, and AC traction substation control methods in the system.

[0005] The present invention adopts the following technical solutions to solve the above technical problems. The present invention provides an electrified railway hybrid through-power supply system, which is used for the same-phase through-power supply and power flow control of the electrified railway. The system is equipped with at least two traction substations, and the traction substations include transformer-type traction substations TS arranged alternately. i And AC-DC-AC traction substation CS j , where i and j are both positive integers ≥ 1 and i ≠ j.

[0006] Furthermore, the transformer type traction substation TS i Including traction transformer TT i , Power flow detection device PS i , traction transformer TT i The primary side is connected to the three-phase grid ABC, and the secondary side is connected to the traction bus TB. i and traction feeder F i Connect to the traction network OCS.

[0007] Furthermore, the AC-DC-AC traction substation CS j Including main transformer T j , AC-DC-AC converter ADA j , Power flow detection device PS j , Power flow controller PL j , main transformer T j The primary side is connected to the three-phase grid ABC, the AC-DC converter ADA j In series with the main transformer T j Secondary and traction busbar TB j Between, traction bus TB j Through traction feeder F j Connect to the traction network OCS.

[0008] Furthermore, the transformer type traction substation TS i The AC-DC-AC traction substation CS j The traction network OCS is connected in phase.

[0009] Furthermore, the power flow controller PL j The input end is connected to the AC / DC traction substation CS through optical fiber FO j Power flow detection device PS j The measuring end and the AC / DC traction substation CS j Adjacent transformer type traction substation TS i Power flow detection device PS i The measuring end.

[0010] Furthermore, the power flow controller PL jThe output end is connected to the AC-DC converter ADA through an optical fiber FO j Control terminal D j , controlling the AC-DC-AC converter ADA j Output to the traction bus TB j The voltage or power meets the preset requirements for the implementation of same-phase through-power supply on electrified railways.

[0011] Preferably, the traction transformer TT i For single-phase transformers or unequal-sided Scott connection transformers.

[0012] Preferably, the transformer type traction substation TS i It also includes a negative sequence compensation device, which includes an SVG structure; wherein the negative sequence compensation device and the traction transformer form a parallel connection structure, or the negative sequence compensation device is connected to the three-phase power grid ABC through a three-phase compensation transformer.

[0013] Preferably, the main transformer T j The three-phase traction transformer, the AC-DC-AC converter ADA j It includes a three-phase rectifier bridge, a DC link and a single-phase inverter bridge.

[0014] Preferably, the transformer type traction substation TS i Power flow detection device PS i Including busbar pressure mutual YH i 、Feeder flow mutual LH i ; The AC-DC-AC traction substation CS j Power flow detection device PS j Including busbar pressure mutual YH j 、Feeder flow mutual LH j .

[0015] As a preferred embodiment, the busbar voltage mutual YH i , busbar voltage mutual YH j Collect traction bus TB separately i TB j The voltage of the feeder current is LH i 、Feeder flow mutual LH j Collect the traction feeder F i 、F j The current is transmitted to the power flow controller PL through the optical fiber FO. j , the power flow controller PL j Calculation, judgment and control are performed based on the voltage and current data transmitted by the optical fiber FO.

[0016] Preferably, the preset requirement is that the transformer type traction substation TSi The AC-DC-AC traction substation CS j The traction network crossing power between them is 0.

[0017] As a preferred embodiment, the through power supply system is provided with two traction substations; when the traction network is in no-load condition, the AC-DC-AC traction substation CS j Traction bus TB j Voltage = adjacent transformer type traction substation TS i Traction bus TB i When the traction network is in load condition, the AC-DC-AC traction substation CS j Output to traction bus TB j The power and adjacent transformer type traction substation TS i Output to traction bus TB i The power ratio of the AC-DC converter ADA j Maximum capacity and traction transformer TT i The maximum capacity is proportional to the ratio.

[0018] Preferably, the through power supply system is provided with at least three traction substations, which are connected to the AC-DC-AC traction substation CS j The two adjacent transformer-type traction substations are TS j-1 TS j+1 , among which, AC-DC-AC traction substation CS j Located in transformer type traction substation TS j-1 TS j+1 When the traction network is in no-load condition, the AC-DC-AC traction substation CS j Traction bus TB j Voltage = Left adjacent transformer type traction substation TS j-1 Traction bus TB j-1 Voltage, or, AC-DC-AC traction substation CS j Traction bus TB j Voltage = right adjacent transformer type traction substation TS j+1 Traction bus TB j+1 When the traction network is in load condition, the AC-DC-AC traction substation CS j Output to traction bus TB j The power is: s j =s j-1 *Smax j / (Smax j +Smax j-1 )+s j+1 *Smax j / (Smax j +Smaxj+1 ),

[0019] in,

[0020] Smax j CS is an AC-DC-AC traction substation j AC-DC-AC Converter ADA j The maximum capacity of

[0021] Smax j-1 The left adjacent transformer type traction substation TS j-1 The maximum capacity of the traction transformer,

[0022] Smax j+1 The right adjacent transformer type traction substation TS j+1 The maximum capacity of the traction transformer,

[0023] s j-1 The left adjacent transformer type traction substation TS j-1 The complex power,

[0024] s j+1 The right adjacent transformer type traction substation TS j+1 The complex power.

[0025] The present invention also provides a power flow control method for a hybrid through-power supply system for an electrified railway, which is applied to a hybrid through-power supply system for an electrified railway with two traction substations, assuming that the traction load power factor is 1, and the current and complex power flow direction to the traction network is +.

[0026] When the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = adjacent transformer type traction substation TS i Traction bus TB i Voltage;

[0027] When the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is not 0, the power flow controller PL j It is determined that the traction network is in a load condition, and the power flow controller PLj Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power and adjacent transformer type traction substation TS i Output to traction bus TB i The power ratio of the AC-DC converter ADA j Maximum capacity and traction transformer TT i The maximum capacity is proportional to the ratio.

[0028] The present invention also provides a power flow control method for a hybrid through-type power supply system for an electrified railway, which is applied to a hybrid through-type power supply system for an electrified railway with at least three traction substations, assuming that the traction load power factor is 1, and the current and complex power flow direction to the traction network is +.

[0029] When the AC-DC-AC traction substation CS j Feeder flow mutual LH j Transmitted to the power flow controller PL j The current is 0, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TS j+1 Feeder flow mutual LH j+1 When the current data calculates that the modulus values ​​of the two currents are both greater than 0 and the modulus value of the sum of the two currents is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = traction bus TB j-1 voltage, or output it to the traction bus TB j Voltage = traction bus TB j+1 Voltage;

[0030] When the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TS j+1 Feeder flow mutual LH j+1 When the modulus of the sum of the two calculated by the current data is greater than 0, the power flow controller PL jIt is determined that the traction network is in a load condition, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 The busbar pressure is YH j-1 and feeder flow mutual LH j-1 The complex power s is calculated from the data j-1 According to the information from the optical fiber FO, the transformer-type traction substation TS on the right is j+1 The busbar pressure is YH j+1 and feeder flow mutual LH j+1 The complex power s is calculated from the data j+1 , the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power is:

[0031] s j =s j-1 *Smax j / (Smax j +Smax j-1 )+s j+1 *Smax j / (Smax j +Smax j+1 ).

[0032] The working principle of the present invention is: assuming that the traction load power factor is 1, the current and complex power flow direction to the traction network is +. In the loop formed by the traction substation, the traction network and the power grid, either an AC-DC-AC type traction substation is set, and its DC link is used to isolate the primary AC power grid and the secondary traction power supply system from each other and block the through power, or control is performed in the following manner in the loop without a DC link.

[0033] In the no-load condition of the traction network, the voltage difference between the two ends of this section of the traction network is controlled to be 0, so that the (through) power of this section of the traction network is 0. Specifically, when the number of traction substations N is 2, when the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = adjacent transformer type traction substation TS iTraction bus TB i voltage; when the number of traction substations N ≥ 3, when the AC-DC-AC traction substation CS j Feeder flow mutual LH j Transmitted to the power flow controller PL j The current is 0, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TS j+1 Feeder flow mutual LH j+1 When the current data calculates that the modulus values ​​of the two currents are both greater than 0 and the modulus value of the sum of the two currents is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = traction bus TB j-1 voltage, or output it to the traction bus TB j Voltage = traction bus TB j+1 voltage.

[0034] Otherwise, the traction network is in a load condition. Under the load condition, the through power of this section of the traction network no longer exists. Specifically, when the number of traction substations N=2, when the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is not 0, the power flow controller PL j It is determined that the traction network is in a load condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power and adjacent transformer type traction substation TS i Output to traction bus TB i The power ratio of the AC-DC converter ADA j Maximum capacity and traction transformer TT i The maximum capacity ratio is proportional to the ratio; when the number of traction substations N ≥ 3, when the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TSj+1 Feeder flow mutual LH j+1 When the modulus of the sum of the two calculated by the current data is greater than 0, the power flow controller PL j It is determined that the traction network is in a load condition, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 The busbar pressure is YH j-1 and feeder flow mutual LH j-1 The complex power s is calculated from the data j-1 According to the information from the optical fiber FO, the transformer-type traction substation TS on the right is j+1 The busbar pressure is YH j+1 and feeder flow mutual LH j+1 The complex power s is calculated from the data j+1 , the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power is: s j =s j-1 *Smax j / (Smax j +Smax j-1 )+s j+1 *Smax j / (Smax j +Smax j+1 ).

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. Utilize the advantages of large transmission capacity and high speed of optical fiber network and data synchronization technology to obtain synchronous data of current and voltage of remote traction substations, and conduct real-time control of local AC / DC traction substations.

[0037] 2. Through power flow control, the through power of the traction network between the transformer-type traction substation and the AC / DC / AC traction substation is reduced to 0, achieving through power supply, eliminating power phase separation and no-power areas, and comprehensively improving the power supply quality of electrified railways. The number of expensive AC / DC / AC traction substations is reduced by more than half, significantly reducing costs and greatly improving cost-effectiveness.

[0038] 3. It has the function of blocking the through power path, or avoiding the generation of through power through control. At the same time, it can complete the power flow control without obtaining (and cannot obtain) the distribution position and number of trains in the system and their operating conditions (traction or braking), and is not affected by other (if any) AC / DC traction substation control methods in the system.

[0039] Fourth, the technical effect of adopting AC, DC and AC traction substations throughout the entire line can be achieved, and even the controllability and performance will be better.

[0040] 5. The present invention has superior performance, advanced technology, reliable method and is easy to implement.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the through power supply system of Example 1 of the present invention.

[0043] Figure 2 It is a schematic diagram of the structure of the through power supply system of Example 2 of the present invention.

[0044] Figure 3a A structural schematic diagram of negative sequence compensation of a transformer-type traction substation according to embodiment 3 of the present invention.

[0045] Figure 3b This is another structural schematic diagram of the negative sequence compensation of the transformer type traction substation according to the third embodiment of the present invention.

[0046] Figure 4 It is a structural schematic diagram of the AC-DC-AC type traction substation power flow controller of the present invention. DETAILED DESCRIPTION

[0047] Example 1

[0048] Figure 1 It is shown that this embodiment provides an electrified railway hybrid through-type power supply system, which is used for the same-phase through-type power supply and power flow control of the electrified railway. The through-type power supply system consists of two traction substations, including a transformer-type traction substation TS1 and an AC-DC-AC traction substation CS2;

[0049] The transformer-type traction substation TS1 includes a traction transformer TT1, a busbar voltage mutual YH1, and a feeder current mutual LH1. The primary side of the traction transformer TT1 is connected to the three-phase power grid ABC, and the secondary side is connected to the traction grid OCS via the traction bus TB1 and the traction feeder F1.

[0050] The AC-DC-AC traction substation CS2 includes a main transformer T2, an AC-DC-AC converter ADA2, a bus voltage mutual YH2, a feeder current mutual LH2, and a power flow controller PL2. The primary side of the main transformer T2 is connected to the three-phase power grid ABC, and the AC-DC-AC converter ADA2 is connected in series between the secondary side of the main transformer T2 and the traction bus TB2. The traction bus TB2 is connected to the traction network OCS via the traction feeder F2;

[0051] The traction network OCS between the transformer type traction substation TS1 and the AC / DC type traction substation CS2 is connected in phase;

[0052] The input end of the flow controller PL2 is connected to the measuring ends of the bus voltage YH2 and the feeder current LH2 of the AC-DC-AC traction substation CS2, and the measuring ends of the bus voltage YH1 and the feeder current LH1 of the transformer-type traction substation TS1 through the optical fiber FO. The output end of the flow controller PL2 is connected to the control end D2 of the AC-DC-AC converter ADA2 through the optical fiber FO, and the AC-DC-AC converter ADA2 is controlled so that the voltage or power output to the traction bus TB2 satisfies the traction network crossing power between the transformer-type traction substation TS1 and the AC-DC-AC traction substation CS2 is 0.

[0053] As an optional embodiment, the traction transformer TT1 is a single-phase transformer, wherein when the three-phase voltage imbalance of the transformer-type traction substation TS1 does not exceed the standard, the use of the single-phase transformer TT1 can meet the power quality requirements of the power grid.

[0054] As an optional embodiment, the traction transformer TT1 may also be an unequal-sided Scott connection transformer.

[0055] As an optional embodiment, the main transformer T2 is a three-phase transformer, and the AC-DC-AC converter ADA2 includes a three-phase rectifier bridge, a DC link and a single-phase inverter bridge.

[0056] As an optional embodiment, a power flow control method for a hybrid through-power supply system of an electrified railway is provided, assuming that the power factor of the traction load is 1, and the direction of the current and complex power flowing to the traction network is +.

[0057] When the current transmitted from the feeder current mutual LH1 of the adjacent transformer-type traction substation TS1 to the power flow controller PL2 is 0, the power flow controller PL2 determines that the section of traction network between the adjacent transformer-type traction substation TS1 and the AC-DC-AC traction substation CS2 is in a no-load condition, and the power flow controller PL2 controls the AC-DC-AC converter ADA2 through the control terminal D2 so that the voltage output to the traction bus TB2 equals the voltage of the traction bus TB1 of the adjacent transformer-type traction substation TS1;

[0058] When the current transmitted by the feeder current mutual LH1 of the adjacent transformer-type traction substation TS1 to the power flow controller PL2 is not zero, the power flow controller PL2 determines that the section of traction network between the adjacent transformer-type traction substation TS1 and the AC-DC-AC traction substation CS2 is in a load condition, and the power flow controller PL2 controls the AC-DC-AC converter ADA2 through the control terminal D2 so that the ratio of the power output to the traction bus TB2 and the power output to the traction bus TB1 by the adjacent transformer-type traction substation TS1 is the same as the power output of the AC-DC-AC converter ADA2. j The maximum capacity is proportional to the ratio of the maximum capacity of the traction transformer TT1.

[0059] Example 2

[0060] Figure 2 It is shown that this embodiment provides a hybrid through-power supply system for electrified railways, which is used for same-phase through-power supply and power flow control of electrified railways. The through-power supply system is equipped with at least three traction substations.

[0061] When there are three traction substations, they are arranged as one transformer-type traction substation + one AC / DC / AC traction substation + one transformer-type traction substation.

[0062] When there are more than 3 substations, they are arranged in a cycle with "one transformer-type traction substation + one AC / DC traction substation + one transformer-type traction substation" as the unit.

[0063] Taking three as an example, there are two transformer-type traction substations TS1 and TS3 and one AC / DC traction substation CS2; the traction network OCS between the AC / DC traction substation CS2 and the left adjacent transformer-type traction substation TS1 and the right adjacent transformer-type traction substation TS3 is connected in the same phase.

[0064] The input end of the flow controller PL2 is connected to the measuring ends of the bus voltage YH2 and the feeder current LH2 of the AC / DC traction substation CS2 through an optical fiber FO, is connected to the measuring ends of the bus voltage YH1 and the feeder current LH1 of the left adjacent transformer-type traction substation TS1 through an optical fiber FO, and is connected to the measuring ends of the bus voltage YH3 and the feeder current LH3 of the right adjacent transformer-type traction substation TS3 through an optical fiber FO. The output end of the flow controller PL2 is connected to the control end D2 of the AC / DC converter ADA2, and the AC / DC converter ADA2 is controlled so that the voltage or power output to the traction bus TB2 satisfies the traction network crossing power between the AC / DC traction substation CS2 and the left adjacent transformer-type traction substation TS1 and the right adjacent transformer-type traction substation TS3 is 0.

[0065] As an optional embodiment, the traction transformers TT1 and TT3 are single-phase transformers. When the three-phase voltage imbalance of the transformer-type traction substations TS1 and TS3 does not exceed the standard, the use of single-phase transformers TT1 and TT3 can meet the power grid's requirements for power quality.

[0066] As an optional embodiment, the traction transformers TT1 and TT3 may also be unequal-sided Scott connection transformers.

[0067] As an optional embodiment, the main transformer T2 is a three-phase transformer, and the AC-DC-AC converter ADA2 includes a three-phase rectifier bridge, a DC link and a single-phase inverter bridge.

[0068] As an optional embodiment, a power flow control method for a hybrid through-power supply system of an electrified railway is provided, assuming that the power factor of the traction load is 1, and the direction of the current and complex power flowing to the traction network is +.

[0069] When the current transmitted to the power flow controller PL2 by the feeder current LH2 of the AC / DC traction substation CS2 is 0, and the power flow controller PL2 calculates the modulus values ​​of the feeder current LH1 of the left adjacent transformer-type traction substation TS1 and the feeder current LH3 of the right adjacent transformer-type traction substation TS3 transmitted by the optical fiber FO and finds that both are greater than 0 and the modulus value of the sum of the two currents is 0, the power flow controller PL2 determines that the section of traction network between the AC / DC traction substation CS2 and the left adjacent transformer-type traction substation TS1 and the right adjacent transformer-type traction substation TS3 is in a no-load condition, and the power flow controller PL2 controls the AC / DC converter ADA2 through the control terminal D2 so that the voltage it outputs to the traction bus TB2 is equal to the voltage of the traction bus TB1, or the voltage it outputs to the traction bus TB2 is equal to the voltage of the traction bus TB3.

[0070] When the power flow controller PL2 calculates the modulus value of the sum of the feeder current LH1 current of the left adjacent transformer-type traction substation TS1 and the feeder current LH3 current data of the right adjacent transformer-type traction substation TS3 transmitted by the optical fiber FO and the two is greater than 0, the power flow controller PL2 determines that the section of traction network between the AC-DC-AC traction substation CS2 and the left adjacent transformer-type traction substation TS1 and the right adjacent transformer-type traction substation TS3 is in a load condition, and the power flow controller PL2 calculates the complex power s1 according to the data of the bus voltage YH1 and the feeder current LH1 of the left adjacent transformer-type traction substation TS1 transmitted by the optical fiber FO, and calculates the complex power s3 according to the data of the bus voltage YH3 and the feeder current LH3 of the right adjacent transformer-type traction substation TS3 transmitted by the optical fiber FO. The power flow controller PL2 controls the AC-DC-AC converter ADA2 through the control terminal D2 so that the power s2 output to the traction bus TB2 is:

[0071] s2=s1*Smax2 / (Smax2+Smax1)+s3*Smax2 / (Smax3+Smax2).

[0072] Among them, Smax2 is the maximum capacity of the AC-DC-AC converter ADA2 of the AC-DC-AC traction substation CS2,

[0073] Smax1 is the maximum capacity of the traction transformer TT1 of the left adjacent transformer-type traction substation TS1,

[0074] Smax3 is the maximum capacity of the traction transformer TT3 of the right adjacent transformer-type traction substation TS3.

[0075] s1 is the complex power calculated by the power flow controller PL2 based on the data of the busbar voltage mutual YH1 and feeder current mutual LH1 of the left adjacent transformer-type traction substation TS1 transmitted by the optical fiber FO.

[0076] s3 is the complex power calculated by the power flow controller PL2 based on the data of the bus voltage YH3 and feeder current LH3 of the right adjacent transformer-type traction substation TS3 transmitted by the optical fiber FO.

[0077] It should be noted that in double-track electrified railways, the traction network is divided into uplink and downlink, and the feeder flow is mutually LH i Should include upstream feeder flow mutual LHs i , Downstream feeder flow mutual LHx i ; Feeder flow mutual LH j Should include upstream feeder flow mutual LHs j , Downstream feeder flow mutual LHx j Among them, the upstream feeder flow is LHs i Used to collect the TS of the transformer type traction substationi The current of the upstream feeder and the downstream feeder are LHx i Used to collect the TS of the transformer type traction substation i The current of the downstream feeder; the current of the upstream feeder j Used to collect the CS of the AC-DC-AC traction substation j The current of the upstream feeder and the downstream feeder are LHx j Used to collect the CS of the AC-DC-AC traction substation j The current of the downstream feeder is the same as above.

[0078] Example 3

[0079] FIG3 shows that this embodiment provides a hybrid through-type power supply system for electrified railways, which is used for same-phase through-type power supply and power flow control of electrified railways. The system is provided with at least two traction substations, and the traction substations include transformer-type traction substations TS arranged alternately. i And AC-DC-AC traction substation CS j , where i and j are both positive integers ≥ 1 and i ≠ j.

[0080] Taking the transformer-type traction substation TS1 as an example, the transformer-type traction substation TS1 includes, in addition to the traction transformer TT1, the busbar voltage mutual YH1, and the feeder current mutual LH1, a negative-sequence compensation device. The negative-sequence compensation device includes an SVG structure. The negative-sequence compensation device is used to compensate for the negative-sequence power of the transformer-type traction substation TS1 so that the three-phase voltage imbalance of the transformer-type traction substation TS1 meets the standard. Preferably, the three-phase voltage imbalance should comply with the relevant provisions of the current "Three-Phase Voltage Unbalance of Electric Energy Quality" GB / T15543.

[0081] As an optional embodiment, Figure 3a As shown, the negative-sequence compensation device and the traction transformer TT1 form a parallel connection structure. Preferably, the negative-sequence compensation device can be a same-phase compensation device, and the traction transformer TT1 can be a single-phase transformer, or an unequal-side Scott connection transformer or other connection forms that can cooperate with the negative-sequence compensation device.

[0082] As an optional embodiment, the same-phase compensation device is connected in parallel with the traction transformer to provide the same-phase voltage to the traction network OCS. Its compensation principle is the same as the compensation principle of a single-phase and three-phase combined same-phase power supply and transformation device in patent ZL201210583674.X or a single-phase combined same-phase power supply and transformation structure in ZL201310227591.1.

[0083] As an optional embodiment, Figure 3bAs shown, the negative sequence compensation device is connected to the three-phase power grid ABC through a three-phase compensation transformer.

Claims

1. An electric railway hybrid through-type power supply system, used for the same-phase through-type power supply and power flow control of the electric railway, characterized in that: The system is equipped with at least two traction substations, which include transformer-type traction substations TS that are alternately arranged. i And AC-DC-AC traction substation CS j , where i and j are both positive integers ≥ 1 and i ≠ j; The transformer type traction substation TS i Including traction transformer TT i , Power flow detection device PS i , traction transformer TT i The primary side is connected to the three-phase grid ABC, and the secondary side is connected to the traction bus TB. i and traction feeder F i Connect to the traction network OCS; The AC-DC-AC traction substation CS j Including main transformer T j , AC-DC-AC converter ADA j , Power flow detection device PS j , Power flow controller PL j , main transformer T j The primary side is connected to the three-phase grid ABC, the AC-DC converter ADA j In series with the main transformer T j Secondary and traction busbar TB j Between, traction bus TB j Through traction feeder F j Connect to the traction network OCS; The transformer type traction substation TS i The AC-DC-AC traction substation CS j The traction network OCS between them is connected in phase; The power flow controller PL j The input end is connected to the AC / DC traction substation CS through optical fiber FO j Power flow detection device PS j The measuring end and the AC / DC traction substation CS j Adjacent transformer type traction substation TS i Power flow detection device PS i The measuring end; Power flow controller PL j The output end is connected to the AC-DC converter ADA through an optical fiber FO j Control terminal D j , controlling the AC-DC-AC converter ADA j Output to the traction bus TB j The voltage or power meets the preset requirements for the implementation of same-phase through-power supply on electrified railways.

2. The hybrid through-power supply system for electrified railway according to claim 1, characterized in that: The traction transformer TT i For single-phase transformers or unequal-sided Scott connection transformers.

3. The hybrid through-power supply system for electrified railway according to claim 2 is characterized in that: The transformer type traction substation TS i It also includes a negative sequence compensation device, which includes an SVG structure; wherein the negative sequence compensation device and the traction transformer form a parallel connection structure, or the negative sequence compensation device is connected to the three-phase power grid ABC through a three-phase compensation transformer.

4. The hybrid through-power supply system for electrified railway according to claim 1, characterized in that: The main transformer T j The three-phase traction transformer, the AC-DC-AC converter ADA j It includes a three-phase rectifier bridge, a DC link and a single-phase inverter bridge.

5. The hybrid through-power supply system for electrified railway according to any one of claims 1 to 4, characterized in that: The transformer type traction substation TS i Power flow detection device PS i Including busbar pressure mutual YH i 、Feeder flow mutual LH i ; The AC-DC-AC traction substation CS j Power flow detection device PS j Including busbar pressure mutual YH j 、Feeder flow mutual LH j .

6. The hybrid through-power supply system for electrified railway according to claim 5, characterized in that: The busbar voltage is YH i , busbar voltage mutual YH j Collect traction bus TB separately i TB j The voltage of the feeder current is LH i 、Feeder flow mutual LH j Collect the traction feeder F i 、F j The current is transmitted to the power flow controller PL through the optical fiber FO. j , the power flow controller PL j Calculation, judgment and control are performed based on the voltage and current data transmitted by the optical fiber FO.

7. The hybrid through-power supply system for electrified railway according to claim 6, characterized in that: The preset requirement is that the transformer type traction substation TS i The AC-DC-AC traction substation CS j The traction network crossing power between them is 0.

8. The hybrid through-power supply system for electrified railway according to claim 7, characterized in that: The through power supply system is equipped with two traction substations; When the traction network is in no-load condition, the AC-DC-AC traction substation CS j Traction bus TB j Voltage = adjacent transformer type traction substation TS i Traction bus TB i Voltage; When the traction network is under load, the AC-DC-AC traction substation CS j Output to traction bus TB j The power and adjacent transformer type traction substation TS i Output to traction bus TB i The power ratio of the AC-DC converter ADA j Maximum capacity and traction transformer TT i The maximum capacity is proportional to the ratio.

9. The hybrid through-power supply system for electrified railway according to claim 7, characterized in that: The through power supply system is equipped with at least three traction substations, which are connected to the AC-DC-AC traction substation CS j The two adjacent transformer-type traction substations are TS j-1 TS j+1 , among which, AC-DC-AC traction substation CS j Located in transformer type traction substation TS j-1 TS j+1 Between, j ≥ 2; When the traction network is in no-load condition, the AC-DC-AC traction substation CS j Traction bus TB j Voltage = Left adjacent transformer type traction substation TS j-1 Traction bus TB j-1 Voltage, or, AC-DC-AC traction substation CS j Traction bus TB j Voltage = right adjacent transformer type traction substation TS j+1 Traction bus TB j+1 Voltage; When the traction network is under load, the AC-DC-AC traction substation CS j Output to traction bus TB j The power is: s j =s j-1 *Smax j / (Smax j +Smax j-1 )+s j+1 *Smax j / (Smax j +Smax j+1 ), in, Smax j CS is an AC-DC-AC traction substation j AC-DC-AC Converter ADA j The maximum capacity of Smax j-1 The left adjacent transformer type traction substation TS j-1 The maximum capacity of the traction transformer, Smax j+1 The right adjacent transformer type traction substation TS j+1 The maximum capacity of the traction transformer, s j-1 The left adjacent transformer type traction substation TS j-1 The complex power, s j+1 The right adjacent transformer type traction substation TS j+1 The complex power.

10. A power flow control method for a hybrid through-type power supply system for an electrified railway, applied to the hybrid through-type power supply system for an electrified railway as claimed in claim 8, characterized in that: Assume that the traction load power factor is 1, the current and complex power flow direction to the traction network is +, When the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = adjacent transformer type traction substation TS i Traction bus TB i Voltage; When the adjacent transformer-type traction substation TS i Feeder flow mutual LH i Transmitted to the power flow controller PL j When the current is not 0, the power flow controller PL j It is determined that the traction network is in a load condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power and adjacent transformer type traction substation TS i Output to traction bus TB i The power ratio of the AC-DC converter ADA j Maximum capacity and traction transformer TT i The maximum capacity is proportional to the ratio.

11. A power flow control method for a hybrid through-type power supply system for an electrified railway, applied to the hybrid through-type power supply system for an electrified railway as claimed in claim 9, characterized in that: Assume that the traction load power factor is 1, the current and complex power flow direction to the traction network is +, When the AC-DC-AC traction substation CS j Feeder flow mutual LH j Transmitted to the power flow controller PL j The current is 0, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TS j+1 Feeder flow mutual LH j+1 When the current data calculates that the modulus of the two currents is greater than 0 and the modulus of the sum of the two currents is 0, the power flow controller PL j It is determined that the traction network is in an unloaded condition, and the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j Voltage = traction bus TB j-1 voltage, or output it to the traction bus TB j Voltage = traction bus TB j+1 Voltage; When the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 Feeder flow mutual LH j-1 The current is related to the adjacent transformer type traction substation TS j+1 Feeder flow mutual LH j+1 When the modulus of the sum of the two calculated by the current data is greater than 0, the power flow controller PL j It is determined that the traction network is in a load condition, and the power flow controller PL j According to the left adjacent transformer type traction substation TS transmitted by optical fiber FO j-1 The busbar pressure is YH j-1 and feeder flow mutual LH j-1 The complex power s is calculated from the data j-1 According to the information from the optical fiber FO, the transformer-type traction substation TS on the right is j+1 The busbar pressure is YH j+1 and feeder flow mutual LH j+1 The complex power s is calculated from the data j+1 , the power flow controller PL j Through the control terminal D j Control the AC-DC-AC converter ADA j Output to the traction bus TB j The power is: S j =s j-1 *Smax j / (Smax j +Smax j-1 )+s j+1 *Smax j / (Smax j +Smax j+1 )。

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