Urban rail transit power supply system voltage class design method and system based on AC3kV

Abstract

The invention discloses a voltage grade design method and system for an urban rail transit power supply system based on AC3kV. The method comprises the following steps: preliminarily determining a new traction power supply voltage grade according to the technical characteristics of the existing urban rail transit power supply voltage grade and the actual demand of new rail transit; designing a new urban rail transit power supply system according to the preliminarily determined new traction power supply voltage grade; a new traction network system of the urban rail transit power supply system is constructed, and the insulation installation technology is adopted for installation; according to the new power supply mode, determining the voltage level of a medium-voltage looped network of the new urban rail transit power supply system; analyzing and verifying the power supply capability and the power supply radius of the new urban rail transit power supply system, and optimizing voltage class parameters according to a verification result; a new thought is provided for the voltage grade design of an urban rail transit power supply system based on AC3kV, and the optimization of the power supply system is realized through scientific and reasonable voltage grade design.

Description

Technical Field

[0001] The present invention relates to the technical field of urban rail transit traction power supply, and particularly relates to a method and system for designing the voltage level of an urban rail transit power supply system based on AC 3 kV. Background Art

[0002] The currently adopted power supply voltage levels for urban rail transit in China are DC 750 V and DC 1500 V. However, their power supply radii are relatively short (the power supply radius of DC 750 V is about 1.5 - 2 km, and the power supply radius of DC 1500 V is about 3.5 - 4 km), making it difficult to meet the long-distance power supply requirements of rail transit express lines (running speeds of 120 - 200 km / h). Due to the large station spacing of rail transit express lines, when using the existing DC power supply system, it is necessary to set up interval substations, increasing the construction difficulty and cost. With the development of rail transit express lines, the adaptability of the existing power supply system in high-speed operation scenarios is insufficient. For example, the running speed of subway express lines has far exceeded the traditional subway design standard (100 km / h), and a higher voltage level is required to meet the power supply demand. When selecting the power supply system, there is a lack of systematic technical and economic comparison and selection, resulting in sub-optimal power supply schemes for some lines.

[0003] Although some studies have proposed preferentially using DC 3000 V power supply in the speed range of 120 - 160 km / h, this system still faces problems of technical maturity and equipment compatibility. The compatibility between different power supply systems (such as DC 750 V, DC 1500 V, DC 3000 V, AC 25 kV) is insufficient, resulting in the inability to directly rescue or operate in mixed formation between trains on different lines. When the existing power supply system undergoes multi-system conversion, there are problems such as complex technology, high equipment cost, and insufficient reliability.

[0004] Some researchers have also proposed a system using AC 3 kV as the traction power supply voltage. The AC 3 kV traction power supply system is a new type of rail transit power supply solution, which can expand the power supply radius and reduce the number of substations, aiming to meet the development needs of urban rail transit with higher speeds, larger passenger volumes, and more energy-efficient and environmentally friendly features. This system shows significant advantages in terms of technology, economy, and engineering applications, and is considered an important development direction for future urban rail transit power supply systems. However, there is still a technical gap in determining the voltage level of the AC 3 kV traction power supply system. For example, although the nominal traction power supply voltage is mentioned as 3 kV in the literature, the relevant national standards and industry specifications have not been fully established. The determination of the voltage level needs to comprehensively consider factors such as power supply capacity, technical maturity of the train traction system, equipment compatibility, and economy, and currently these aspects are still in the research and exploration stage. These problems need to be solved through further research and practice to promote the wide application of the AC 3 kV traction power supply system in urban rail transit.

[0005] In addition, "Rated Voltage for DC Electric Traction" GB / T 999-2021 stipulates the nominal voltage and allowable limit values of the traction power supply system (DC 750V, DC 1500V, DC 3000V). "Rail Transit Traction Power Supply System Voltage" GB / T 1402-2010 stipulates the traction voltage levels DC 750V, DC 1500V, and AC 25kV used in rail transit. Currently, there is no regulation on the allowable limit values of the AC 3kV traction voltage level.

[0006] Therefore, there is an urgent need to study a design method for the allowable limit values of the voltage level of an urban rail transit power supply system based on AC 3kV. Summary of the Invention

[0007] The present invention aims to provide a design method specifically applicable to the voltage level of an urban rail transit power supply system based on AC 3kV. Based on the technical characteristics of AC 25kV and the vehicle starting voltage requirements, three-phase alternating current 3kV is determined as the new traction power supply voltage level, and the technical indicators of the new traction power supply voltage level are formulated; the continuous voltage and non-continuous voltage ranges are clarified, and the minimum continuous voltage and the maximum continuous voltage of the system are determined; a new industry standard is set for the limit values of the AC 3kV traction voltage level, which not only improves the efficiency and reliability of the power supply system but also lays a solid foundation for the future development of the urban rail transit power supply system; adopting the AC 3kV power supply system provides the advantages of a higher voltage level and AC power supply, and can significantly improve the power supply capacity, power supply radius, and power quality; the AC 3kV power supply system realizes the lightweight of the train by canceling the on-vehicle traction transformer and supports a higher traction network voltage, further improving the system efficiency; it not only breaks through the limitations of the traditional power supply system in technology but also shows significant advantages in economy, compatibility, and intelligence; this design method provides an efficient, flexible, and sustainable solution for the future development of urban rail transit.

[0008] In view of the above defects or improvement requirements of the prior art, the first aspect of the present invention provides a design method for the voltage level of an urban rail transit power supply system based on AC 3kV, including:

[0009] S1: Initially determine the new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit.

[0010] S2: Design a new urban rail transit power supply system according to the initially determined new traction power supply voltage level.

[0011] S3: Construct the traction network 5 of the new urban rail transit power supply system and install it using insulation installation technology.

[0012] S4: Determine the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode;

[0013] S5: Analyze and verify the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimize the voltage level parameters according to the verification results.

[0014] Furthermore, in step S1, determining the new traction power supply voltage level according to the technical characteristics of the existing voltage level and the actual requirements of the new rail transit includes:

[0015] S11: Analyze the technical characteristics of the existing voltage level, determine its limitations; consider the advantages of the AC3kV voltage level; evaluate the adaptability of the existing equipment to AC3kV;

[0016] S12: Analyze the actual requirements of the new rail transit, and clarify the design objectives of the new traction power supply voltage level;

[0017] S13: Determine the voltage level. Considering the technical characteristics of the existing voltage level and the actual requirements of the new rail transit, determine AC3kV as the traction power supply voltage level.

[0018] Furthermore, in step S13, determining AC3kV as the traction power supply voltage level by integrating the technical characteristics of the existing voltage level and the actual requirements of the new rail transit includes:

[0019] S131: Conduct technical selection and parameter analysis according to the design objectives of the new traction power supply voltage level;

[0020] S132: Calculate the power supply distance, energy consumption, and equipment parameters under different candidate voltage levels. At the same time, consider the requirements of overvoltage protection and insulation coordination;

[0021] S133: Based on the technical characteristics of AC25kV and the vehicle starting voltage requirements, determine three-phase alternating current 3kV as the new traction power supply voltage level, and formulate the technical index of the allowable limit value under the AC3kV power supply voltage level of the new traction power supply system.

[0022] Furthermore, the formulation of the technical index of the allowable limit value under the AC3kV power supply voltage level of the new traction power supply system in step S133 includes: clarify the continuous voltage and non-continuous voltage ranges, and determine the minimum continuous voltage and the maximum continuous voltage of the system; among them:

[0023] Minimum non-continuous voltage: 2.2kV;

[0024] Minimum continuous voltage: 2.4kV;

[0025] Maximum continuous voltage: 3.3kV;

[0026] Maximum non-sustained voltage: 3.6 kV.

[0027] Furthermore, in step S2, designing a new urban rail transit power supply system according to the newly determined traction power supply voltage level includes:

[0028] S21: Determine the basic composition of the new urban rail transit power supply system, including main substations 1, medium-voltage ring networks 2, traction and step-down hybrid substations 3, step-down substations 4, traction transformers, AC 3 kV switchgears, traction networks 5, and locomotives;

[0029] S22: Construct the traction network 5 and install it using insulation installation technology;

[0030] S23: Determine the voltage level of the medium-voltage ring network 2 according to the power supply mode.

[0031] Furthermore, in step S3, the traction network 5 includes a positive contact rail A, a negative contact rail B, and a grounded running rail C;

[0032] Installing the traction network of the traction power supply system using insulation installation technology includes:

[0033] Insulation installation of the positive contact rail A and the negative contact rail B. When the grounded running rail C is not grounded, the vehicle body is in contact with the running rail, and insulation design is carried out for the vehicle body;

[0034] Strengthen the insulation design of the vehicle body against the ground at the platform screen door to avoid electric shock to personnel;

[0035] When the running rail C is designed to be grounded, the voltages of the positive contact rail A and the negative contact rail B to the ground (i.e., the running rail C) are line voltages, and the voltages between phases do not affect each other;

[0036] The input voltage of the rectifier on the locomotive is 3 kV both between phases and to the ground.

[0037] Furthermore, in step S4, determining the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode includes:

[0038] Select AC 35 kV for centralized power supply and AC 10 kV for decentralized power supply;

[0039] Adopt AC 3 kV as the traction power supply voltage, and the voltage level for centralized power supply can be selected from AC 25 kV, AC 35 kV, or AC 55 kV;

[0040] The traction power supply system is powered by 110 kV - 35 kV - 3 kV;

[0041] The power and lighting power supply system is powered by 110 kV - 35 kV - 0.4 kV;

[0042] For the traction power supply system with decentralized power supply, 10 kV - 3 kV is used for power supply;

[0043] For the power supply system of power and lighting, 10 kV - 0.4 kV is used for power supply.

[0044] Furthermore, in step S5, analyzing and verifying the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimizing the voltage level parameters according to the verification results include:

[0045] S51: Based on the theoretical calculation method, evaluate the maximum traction power and the power supply range of a single traction step-down hybrid substation under different voltage levels;

[0046] S52: Compare the performance indicators (such as energy consumption, efficiency, reliability, etc.) of the AC 3 kV system with the existing DC power supply system, and verify the advantages of adopting the new traction power supply voltage level;

[0047] S53: Conduct actual working condition verification through simulation software or experimental platform, analyze the performance of the new traction power supply system under different operating conditions, and optimize the voltage level parameters according to the verification results.

[0048] The second aspect of the present invention provides a voltage level design system for an urban rail transit power supply system based on AC 3 kV, which is used to implement the voltage level design method for the urban rail transit power supply system based on AC 3 kV, including a first main module, a second main module, a third main module, a fourth main module, and a fifth main module;

[0049] The first main module is used to initially determine the new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit;

[0050] The second main module is used to design a new urban rail transit power supply system according to the initially determined new traction power supply voltage level;

[0051] The third main module is used to construct the traction network 5 of the new urban rail transit power supply system and install it using insulation installation technology;

[0052] The fourth main module is used to determine the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode;

[0053] The fifth main module is used to analyze and verify the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimize the voltage level parameters according to the verification results.

[0054] In a third aspect of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program, which is executed by a processor to perform any one of the steps of the above-mentioned voltage level design method for an urban rail transit power supply system based on AC 3 kV.

[0055] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0056] 1. The voltage level design method for an urban rail transit power supply system based on AC 3 kV of the present invention, by carefully analyzing the technical characteristics and limitations of existing power supply systems such as DC 750 V, DC 1500 V, AC 25 kV, etc., and combining the specific requirements of new rail transit for power supply capacity, power supply radius, equipment compatibility, economy and safety, innovatively proposes to use AC 3 kV as the new traction power supply voltage level. The selection of this voltage level can not only provide higher power supply capacity and longer power supply radius, but also effectively reduce current loss and reduce the number of substations, thereby improving the system efficiency while reducing the construction and operation and maintenance costs.

[0057] 2. The voltage level design method for an urban rail transit power supply system based on AC 3 kV of the present invention, based on an in-depth analysis of the technical characteristics of the AC 25 kV system and the train starting voltage requirements, innovatively sets the three-phase alternating current 3 kV as the new generation of traction power supply voltage level, and accordingly formulates a set of new traction power supply voltage technical indicators. These indicators not only clarify the ranges of continuous voltage and non-continuous voltage, but also precisely specify the values of the minimum continuous voltage and the maximum continuous voltage of the system. Thus, a new industry standard is set for the limit values of the AC 3 kV traction voltage level, which not only improves the efficiency and reliability of the power supply system, but also lays a solid foundation for the future development of urban rail transit power supply systems.

[0058] 3. The voltage level design method for an urban rail transit power supply system based on AC 3 kV of the present invention covers the detailed design of an urban rail transit power supply system based on AC 3 kV, including key components such as main substations, medium-voltage ring networks, traction step-down hybrid substations, step-down substations, traction transformers, AC 3 kV switch cabinets, traction network systems and locomotives. In particular, the construction of the traction network system and the adoption of insulation installation technology, as well as the determination of the medium-voltage ring network voltage level, all reflect the high attention paid to the safety and reliability of the power supply system.

[0059] 4. The voltage level design method of the urban rail transit power supply system based on AC 3 kV of the present invention analyzes and verifies the power supply capacity and power supply radius of the new power supply system, and optimizes the voltage level parameters according to the verification results. This design method not only provides a new idea for the voltage level design of the urban rail transit power supply system based on AC 3 kV, but also ensures the feasibility and effectiveness of the design through actual verification. The implementation of this method will contribute to the progress of urban rail transit power supply technology, meet the needs of future rail transit development, and has important practical value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a flowchart of the voltage level design method of the urban rail transit power supply system based on AC 3 kV according to an embodiment of the present invention;

[0061] Figure 2 is a schematic structural diagram of the urban rail transit power supply system based on AC 3 kV according to an embodiment of the present invention;

[0062] Figure 3 is a schematic structural diagram of the voltage level design system of the urban rail transit power supply system based on AC 3 kV according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0064] One aspect of the present invention provides a voltage level design method of an urban rail transit power supply system based on AC 3 kV, including the following steps:

[0065] S1: Initially determine a new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit;

[0066] S2: Design a new urban rail transit power supply system according to the initially determined new traction power supply voltage level;

[0067] S3: Construct a traction network 5 of the new urban rail transit power supply system and install it using insulation installation technology;

[0068] S4: Determine the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode;

[0069] S5: Analyze and verify the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimize the voltage level parameters according to the verification results.

[0070] Further, in step S1, initially determine the new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit; including:

[0071] S11: Analyze the technical characteristics of the existing voltage levels, determine their limitations; consider the advantages of the AC3kV voltage level; evaluate the adaptability of the existing equipment to AC3kV;

[0072] S12: Analyze the actual requirements of the new rail transit, and clarify the design objectives of the new traction power supply voltage level;

[0073] S13: Determine the voltage level. Considering the technical characteristics of the existing voltage levels and the actual requirements of the new rail transit, determine AC3kV as the traction power supply voltage level;

[0074] Further, in step S11, the analysis of the technical characteristics of the existing voltage levels, determining their limitations; considering the advantages of the AC3kV voltage level; evaluating the adaptability of the existing equipment to AC3kV; includes:

[0075] S111: Analyze the technical characteristics of the existing power supply system voltage levels (such as DC750V, DC1500V, AC25kV, etc.) of urban rail transit in terms of power supply capacity, power supply radius, equipment compatibility, economy, and safety, and determine their limitations;

[0076] Specifically as follows:

[0077] Power supply capacity:

[0078] DC750V: The power supply radius is relatively short (about 1.5 - 2 km), suitable for low-speed and short-distance subway lines;

[0079] DC1500V: The power supply radius is longer (about 3.5 - 4 km), suitable for medium-speed and medium-distance subway lines;

[0080] AC25kV: The power supply radius is the longest (10 - 20 km), suitable for high-speed and large-capacity railway systems;

[0081] Equipment complexity:

[0082] DC systems (DC750V / 1500V): The equipment is relatively simple, mainly composed of rectifier units, DC switch cabinets, etc.;

[0083] AC system (AC 25 kV): The equipment is complex and requires traction transformers and overhead catenaries. Although it has strong power supply capacity, the high voltage level may pose safety risks, and the equipment has poor compatibility.

[0084] Economy:

[0085] DC 750 V / 1500 V: The equipment cost is low, but its power supply distance is limited and the power supply radius is short, resulting in a relatively large number of traction step-down hybrid substations, increasing the construction and operation and maintenance costs.

[0086] DC 3000 V: The power supply distance is doubled compared with DC 1500 V, reducing the number of substations and having better economic benefits.

[0087] AC 25 kV: The equipment cost is high, but the power supply radius is long, suitable for long-distance lines.

[0088] Safety:

[0089] DC system: The insulation requirement is relatively low, but the voltage fluctuation range is relatively large.

[0090] AC system: The insulation requirement is high, the voltage fluctuation range is small, and the power supply stability is high.

[0091] S112: Consider the advantages of the AC 3 kV voltage level, such as higher power supply capacity, longer power supply radius, lower current loss, etc.

[0092] Advantages of the AC 3 kV voltage level include:

[0093] Higher power supply capacity: Compared with traditional DC 1.5 kV or DC 750 V power supply systems, the AC 3 kV voltage level can provide higher power supply capacity. Under the same line conditions, the maximum output power of the AC 3 kV power supply system is significantly improved, meeting the requirements of larger traffic volume and higher operating speed.

[0094] Longer power supply radius: Due to the increase in voltage level, the AC 3 kV power supply system has smaller current loss during transmission, thus enabling a longer power supply radius. Compared with the DC 1.5 kV power supply scheme, when the medium-voltage cable voltage level is 66 kV, the number of traction step-down hybrid substations in the AC 3 kV power supply scheme can be reduced by 8, significantly reducing the construction cost.

[0095] Lower current loss: The AC 3 kV power supply system has a smaller current during transmission, so the line loss is lower. This not only improves the power supply efficiency but also reduces energy waste. The system also supports the efficient utilization of regenerative braking energy, further enhancing the energy-saving effect.

[0096] Lightweight design of trains: The on-board traction transformer is eliminated in the AC 3 kV power supply system, achieving the lightweight of trains and further improving the load-bearing efficiency and energy-saving rate of trains;

[0097] Problem of stray current: There is a problem of stray current in the DC power supply system, which can cause electrochemical corrosion to underground metal pipelines and foundation steel structures. However, there is no problem of stray current in the AC 3 kV power supply system, which is safer for urban underground facilities;

[0098] Higher economy and technology: In terms of economy, the cost of the AC 3 kV power supply system in the whole life cycle is significantly lower than that of the traditional DC 1.5 kV power supply system; for example, when the voltage grade of the medium-voltage cable is 66 kV, the total costs of the three-phase AC 3 kV and single-phase AC 3 kV power supply schemes are reduced by 17.5% and 18.24% respectively;

[0099] In terms of technology, the AC 3 kV power supply system supports long-distance uninterrupted power supply, improves the flexibility of the location selection of main substations, and introduces sectional protection and measurement and control technology, improving the reliability and flexibility of power supply;

[0100] Compatibility and expandability: The AC 3 kV power supply system can be compatible with single-phase and three-phase power receiving methods, and is suitable for the transformation of new lines and existing lines; this system also provides a unified power supply method for the interconnection of trunk railways and urban rail transit, laying a foundation for future technology upgrading and expansion;

[0101] It can be seen that the AC 3 kV voltage grade has significant technical and economic advantages in the urban rail transit power supply system, and can better meet the requirements of the new era of rail transit for higher efficiency, longer power supply distance and lower energy consumption;

[0102] S113: Evaluate the adaptability of existing equipment (such as traction step-down hybrid substations, overhead catenaries, train traction systems) to AC 3 kV;

[0103] Furthermore, in step S12, analyze the actual requirements of the new rail transit, and clarify the design objectives of the new traction power supply voltage grade; including:

[0104] According to the actual requirements of the new rail transit, calculate the power and energy required by the power supply system;

[0105] The power and energy of the power supply system need to meet the requirements of long distance and high traffic volume, while reducing the number of substations and energy consumption;

[0106] According to the planning of the new rail transit line, including line length, train operation density, train traction power demand, etc., determine whether a higher voltage grade is required;

[0107] Considering the need for future scalability and technology upgrades, ensure that the new voltage level can meet the long-term operation requirements;

[0108] Furthermore, for the determination of the voltage level in step S13, considering the technical characteristics of the existing voltage levels and the actual requirements of the new rail transit, determine AC3kV as the traction power supply voltage level; including:

[0109] S131: Conduct technical selection and parameter analysis according to the design objectives of the new traction power supply voltage level;

[0110] Select the voltage type:

[0111] Select the AC or DC power supply mode according to the design objectives; for example, the AC system is suitable for long-distance power supply, while the DC system is more common in urban rail transit;

[0112] Determine the voltage level range:

[0113] Combining the actual requirements and existing technical experience, preliminarily draw up several candidate voltage levels (such as AC3kV, AC25kV, etc.);

[0114] Analyze the technical feasibility of the candidate voltage levels. Among them, the technical characteristics of the existing AC25kV are as follows:

[0115] Power supply capacity: The AC25kV power supply system has a long power supply radius (10 - 20 km) and high traction power, and is suitable for high-speed and large-capacity railways;

[0116] Equipment complexity: The AC25kV system requires complex equipment such as traction transformers and overhead lines, and has high insulation requirements;

[0117] Economy and energy saving: Although the equipment cost is high, the power supply capacity is strong, suitable for long-distance lines, and has good energy-saving effects;

[0118] Vehicle starting voltage requirements: The AC25kV system requires the train traction system to have a high insulation level and adaptability to ensure stable operation under high voltage;

[0119] The technical requirements for the AC3kV voltage level are as follows:

[0120] Power supply capacity and power supply radius: The AC3kV system needs to meet the requirements of the urban rail transit express line in terms of power supply capacity and power supply radius, while reducing the number of substations;

[0121] Train lightweight: Cancel the on-board traction transformer, and use a 4.5kV IGBT to construct a three-level topology traction converter to achieve train lightweight;

[0122] S132: Calculate the power supply distance, energy consumption, and equipment parameters (such as transformer capacity, switchgear specifications, etc.) at different candidate voltage levels. At the same time, consider the requirements of overvoltage protection and insulation coordination;

[0123] For a DC power supply system, the relationship between the power supply radius and the power supply voltage level is as follows:

[0124]

[0125] In the formula, L is the power supply radius (m), ΔU% is the voltage loss percentage, R0 is the unit resistance of the line (Ω), U is the power supply voltage, and I is the current (A); the power supply radius L is directly proportional to the power supply voltage U and inversely proportional to the current I and the unit resistance R0 of the line;

[0126] In practical applications, to increase the power supply radius, the power supply voltage level is usually increased, and the current and the unit resistance of the line are reduced. For example, increasing from DC1500V to DC3000V can significantly increase the power supply radius, thereby reducing the number of traction step-down hybrid substations and improving the power supply efficiency.

[0127] S133: Based on the technical characteristics of AC25kV and the vehicle starting voltage requirements, determine 3kV three-phase AC as the new traction power supply voltage level and formulate the technical indicators of the new traction power supply voltage level;

[0128] Furthermore, as shown in Table 1, the minimum continuous voltage, maximum continuous voltage, and ratio of the voltage level design given by the DC system are fixed at different nominal voltages of 750V, 1500V, and 3000V;

[0129] Table 1 Existing traction power supply system voltage level parameter table

[0130]

[0131] Therefore, based on the minimum voltage and minimum voltage of AC25kV and the vehicle starting voltage, formulate the technical indicators of the limit values allowed under the AC3kV power supply voltage level of the new traction power supply system;

[0132] The formulation of the technical indicators of the limit values allowed under the AC3kV power supply voltage level of the new traction power supply system described in step S133 includes: clarifying the continuous voltage and non-continuous voltage ranges, and determining the minimum continuous voltage and maximum continuous voltage of the system; among them:

[0133] Minimum non-continuous voltage: 2.2kV (the lowest voltage allowed in a short time);

[0134] Minimum continuous voltage: 2.4kV (the lowest voltage at which the train can continuously operate);

[0135] Maximum continuous voltage: 3.3 kV (the highest voltage during normal train operation);

[0136] Maximum non - continuous voltage: 3.6 kV (the highest voltage allowed for a short period);

[0137] Determine the insulation level and protection measures of the system: Ensure that the insulation strength of the equipment can withstand the maximum over - voltage, and at the same time design a reliable over - voltage protection device.

[0138] Further, in step S2, design a new urban rail transit power supply system according to the newly determined traction power supply voltage level; including:

[0139] S21: Determine the basic composition of the new urban rail transit power supply system, including main substation 1, medium - voltage ring network 2, traction - step - down combined substation 3, step - down substation 4, traction transformer, AC3 kV switchgear, traction network 5 and locomotives;

[0140] Figure 2 It is a structural schematic diagram of an urban rail transit power supply system based on AC3 kV;

[0141] The main substation 1 is the power core of the power supply system, responsible for stepping down the external high - voltage alternating current of 110 kV or 220 kV to 35 kV or 66 kV; the medium - voltage ring network 2 (AC35 kV) serves as the intermediate transmission link for AC35 kV three - phase electricity, and transmits electric energy through medium - voltage cables to each traction - step - down combined substation 3 and step - down substation 4; the traction - step - down combined substation 3 receives the AC35 kV three - phase electricity from the medium - voltage ring network, and further steps down the medium - voltage electric energy to AC3 kV through the traction transformer for exclusive use in the traction power supply system; each traction - step - down combined substation 3 feeds out 4 feeder lines to the traction network 5 to supply power to the train; the step - down substation 4 mainly provides low - voltage power for auxiliary facilities such as lighting, ventilation, and communication in the station; the step - down substation 4 also obtains electric energy from the AC35 kV medium - voltage ring network 2 and steps it down to low - voltage electricity suitable for in - station equipment and auxiliary systems; specifically, the external high - voltage electricity (such as 110 kV or 220 kV) is stepped down to AC35 kV three - phase electricity by the main substation 1 from the power grid. This three - phase electricity serves as the medium - voltage power supply and is transmitted through the medium - voltage ring network 2 to all traction - step - down combined substations 3 and step - down substations 4 along the line to supply power to them. The traction - step - down combined substation 3 receives the AC35 kV three - phase electricity from the medium - voltage ring network 3, and through two traction transformers, respectively feeds out 4 feedback lines to further step down the AC35 kV three - phase electricity to AC3 kV and then supplies power to the train through the traction network 5; the 2 feedback lines fed out by one traction transformer for the up - line power supply are defined as phase A, and the 2 feedback lines fed out by the other traction transformer for the up - line power supply are defined as phase B, and the running rail serves as phase C to form a return path.

[0142] Furthermore, the traction transformer adopts the Yd11 wiring form to convert medium-voltage electric energy into AC 3 kV electric energy suitable for the use of the traction network 5; the AC 3 kV switchgear is used to control and protect the power distribution of the traction power supply system to ensure the safety and reliability of power supply; the traction network 5 is the power supply network of the train, and the AC 3 kV electric energy fed out by the traction step-down hybrid substation is supplied to the train through the contact rail or catenary; the AC 3 kV system can be powered in the form of the third rail (supplying power to the train through the contact rail), the fourth rail (adding an additional return rail on the basis of the third rail), or catenary power supply (obtaining electric energy from the catenary through the pantograph); the locomotive adopts a lightweight design, cancels the on-vehicle traction transformer, and improves the load-carrying efficiency and energy-saving rate of the train; the locomotive can adapt to the voltage level of the AC 3 kV power supply system to ensure the stability and safety of the train under different operating conditions.

[0143] Furthermore, in step S3, the AC 3 kV electric energy fed out by the traction step-down hybrid substation 3 to the traction network 5 is supplied to the train through the contact rail or catenary; the traction network 5 includes the positive contact rail A, the negative contact rail B, and the grounding running rail C; the insulation installation technology is used to install the traction network of the traction power supply system to reduce the leakage current loss and improve the system efficiency;

[0144] Using the insulation installation technology to install the traction network of the traction power supply system includes:

[0145] The positive contact rail A and the negative contact rail B are installed insulatively, and when the grounding running rail C is not grounded, the vehicle body is in contact with the running rail, and the vehicle body is insulatedly designed;

[0146] At the platform screen door, the ground insulation design of the vehicle body is strengthened to avoid electric shock to people;

[0147] When the running rail C is grounded, the voltages of the positive contact rail A and the negative contact rail B to the ground (i.e., the running rail C) are line voltages, and the voltages between phases do not affect each other;

[0148] The input voltage of the rectifier on the locomotive is 3 kV both between phases and to the ground; considering comprehensively the safety and technicality, it is recommended that the running rail be installed grounded.

[0149] Furthermore, in step S4, determining the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode includes:

[0150] When centralized power supply is adopted, AC 35 kV is selected, and when decentralized power supply is adopted, AC 10 kV is selected;

[0151] Using AC 3 kV as the traction power supply voltage, the voltage level during centralized power supply can be selected as AC 25 kV, AC 35 kV, or AC 55 kV;

[0152] When the traction power supply voltage level is fixed, the higher the voltage level of the medium-voltage ring network 2, the stronger the power supply capacity. Considering the current application of urban rail transit voltage levels comprehensively, it is recommended to still adopt AC35kV for the medium-voltage ring network of centralized power supply. The traction power supply system is powered by 110kV - 35kV - 3kV, and the power supply system for power and lighting is powered by 110kV - 35kV - 0.4kV. For the decentralized power supply mode, the traction power supply system is powered by 10kV - 3kV, and the power supply system for power and lighting is powered by 10kV - 0.4kV.

[0153] Furthermore, in step S5, analyzing and verifying the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimizing the voltage level parameters according to the verification results include:

[0154] S51: Based on the theoretical calculation method, evaluate the maximum traction power and the power supply range of a single traction step-down hybrid substation under different voltage levels;

[0155] S52: Compare the performance indicators (such as energy consumption, efficiency, reliability, etc.) of the AC3kV system with the existing DC power supply system, and verify the advantages of adopting the new traction power supply voltage level;

[0156] S53: Conduct actual working condition verification through simulation software or experimental platform, analyze the performance of the new traction power supply system under different operating conditions, and optimize the voltage level parameters according to the verification results.

[0157] Since a higher voltage can reduce the loss during current transmission, thereby extending the power supply distance and reducing the number of traction step-down hybrid substations; when other conditions are the same, compared with DC1500V, the power supply capacity of the DC3000V power supply system can be increased by about one time, and the number of traction step-down hybrid substations is reduced by half.

[0158] Since the effective value of three-phase alternating current is times (about 1.732 times) that of single-phase alternating current, therefore, the power supply capacity of three-phase AC 3kV is about 1.732 times that of single-phase AC 3kV. Under the same voltage level, three-phase alternating current can transmit more power; when adopting AC3kV power supply, the voltage level is doubled compared with DC1500V, and the power supply capacity is about 4 times that of DC1500V.

[0159] As Figure 3 shown, the second aspect of the present invention provides a voltage level design system for an urban rail transit power supply system based on AC3kV, including a first main module, a second main module, a third main module, a fourth main module, and a fifth main module;

[0160] The first main module is used to preliminarily determine a new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit.

[0161] The second main module is used to design a new urban rail transit power supply system according to the preliminarily determined new traction power supply voltage level.

[0162] The third main module is used to construct the traction network 5 of the new urban rail transit power supply system and install it using insulation installation technology.

[0163] The fourth main module is used to determine the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode.

[0164] The fifth main module is used to analyze and verify the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimize the voltage level parameters according to the verification results.

[0165] The third aspect of the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, any step of the design calculation method of the urban rail transit AC3kV traction power supply system can be realized.

[0166] The computer-readable storage medium may include: various media such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs that can store program codes.

[0167] For the introduction of the computer-readable storage medium provided in this application, please refer to the above method embodiments, and this application will not be elaborated here.

[0168] Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A voltage level design method for the power supply system of urban rail transit based on AC 3 kV, characterized in that, Including: S1: Initially determine a new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit; S2: Design a new urban rail transit power supply system according to the initially determined new traction power supply voltage level; S3: Construct the traction network 5 of the new urban rail transit power supply system and install it using insulation installation technology; S4: Determine the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode; S5: Analyze and verify the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimize the voltage level parameters according to the verification results.

2. A voltage level design method for an urban rail transit power supply system based on AC 3 kV according to claim 1, characterized in that Including: Determining the new traction power supply voltage level according to the technical characteristics of the existing voltage level and the actual requirements of the new rail transit in step S1; including: S11: Analyze the technical characteristics of the existing voltage level, determine its limitations; consider the advantages of the AC3kV voltage level; Evaluate the adaptability of existing equipment to AC3kV; S12: Analyze the actual requirements of the new rail transit, and clarify the design objectives of the new traction power supply voltage level; S13: Determine the voltage level, and comprehensively consider the technical characteristics of the existing voltage level and the actual requirements of the new rail transit to determine AC3kV as the traction power supply voltage level.

3. A voltage level design method for an urban rail transit power supply system based on AC 3 kV according to claim 2, characterized in that, Comprehensively considering the technical characteristics of the existing voltage level and the actual requirements of the new rail transit in step S13 to determine AC3kV as the traction power supply voltage level; including: S131: Conduct technical selection and parameter analysis according to the design objectives of the new traction power supply voltage level; S132: Calculate the power supply distance, energy consumption, and equipment parameters under different candidate voltage levels, and at the same time, consider the requirements of overvoltage protection and insulation coordination; S133: Based on the technical characteristics of AC25kV and the vehicle starting voltage requirements, determine three-phase alternating current 3kV as the new traction power supply voltage level, and formulate the technical indicators of the allowable limit values under the AC3kV power supply voltage level of the new traction power supply system.

4. A design method for the voltage level of an urban rail transit power supply system based on AC 3 kV according to claim 3, characterized in that, The formulation of the technical indicators of the allowable limit values under the AC3kV power supply voltage level of the new traction power supply system in step S133 includes: clarify the continuous voltage and non-continuous voltage ranges, and determine the minimum continuous voltage and the maximum continuous voltage of the system; where: Minimum non-continuous voltage: 2.2kV; Minimum continuous voltage: 2.4kV; Maximum continuous voltage: 3.3kV; Maximum non-continuous voltage: 3.6kV.

5. A voltage level design method for an urban rail transit power supply system based on AC 3 kV according to any one of claims 1-4, characterized in that, The new urban rail transit power supply system in step S2 includes a main substation 1, a medium-voltage ring network 2, a traction step-down hybrid substation 3, a step-down substation 4, a traction transformer, an AC3kV switch cabinet, a traction network 5, and a locomotive; The high-voltage alternating current from the power grid is stepped down to three-phase power of AC35kV after passing through the main substation 1, and the stepped-down three-phase power of AC35kV is transmitted through the medium-voltage ring network 2 to the traction step-down hybrid substation 3 and the step-down substation 4 of the whole line. The traction step-down hybrid substation 3 receives the three-phase power of AC35kV from the medium-voltage ring network 3 and is further stepped down to AC3kV through the traction transformer for exclusive use in the traction power supply system; the traction step-down hybrid substation 3 usually feeds out multiple feeder lines to the traction network 5.

6. A design method for the voltage level of an urban rail transit power supply system based on AC 3 kV, characterized in that, In step S3, the traction network 5 includes a positive contact rail A, a negative contact rail B, and a grounded running rail C; The traction network of the traction power supply system is installed using an insulation installation technique, including: The positive contact rail A and the negative contact rail B are installed insulatively. When the grounded running rail C is not grounded, the vehicle body contacts the running rail, and an insulation design is carried out for the vehicle body; At the platform screen door, the insulation design of the vehicle body against the ground is strengthened to avoid electric shock to personnel; When the running rail C is grounded, the voltages of the positive contact rail A and the negative contact rail B to the ground (i.e., the running rail C) are line voltages, and the voltages between phases do not affect each other; The input voltage of the rectifier on the locomotive is 3 kV both between phases and to the ground.

7. A voltage level design method for an urban rail transit power supply system based on AC 3 kV according to claim 5, characterized in that In step S4, determining the voltage level of the medium-voltage ring network 2 of the new urban rail transit power supply system according to the new power supply mode includes: Selecting AC 35 kV for centralized power supply and AC 10 kV for decentralized power supply; Using AC 3 kV as the traction power supply voltage, and selecting AC 25 kV, AC 35 kV or AC 55 kV for the voltage level in centralized power supply; The traction power supply system is powered by 110 kV - 35 kV - 3 kV; The power and lighting power supply system is powered by 110 kV - 35 kV - 0.4 kV; For the traction power supply system with a decentralized power supply mode, it is powered by 10 kV - 3 kV; The power and lighting power supply system is powered by 10 kV - 0.4 kV.

8. A design method for the voltage level of an urban rail transit power supply system based on AC 3 kV according to any one of claims 1-4, 6 or 7, characterized in that In step S5, analyzing and verifying the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimizing the voltage level parameters according to the verification results includes: S51: Based on the theoretical calculation method, evaluate the maximum traction power and the power supply range of a single traction step-down hybrid substation under different voltage levels; S52: Compare the performance indicators (such as energy consumption, efficiency, reliability, etc.) of the AC 3 kV system with the existing DC power supply system, and verify the advantages of adopting the new traction power supply voltage level; S53: Conduct actual working condition verification through simulation software or experimental platform, analyze the performance of the new traction power supply system under different operating conditions, and optimize the voltage level parameters according to the verification results.

9. A voltage level design system for an urban rail transit power supply system based on AC 3 kV, characterized in that, Including: The first main module is used to initially determine the new traction power supply voltage level according to the technical characteristics of the existing urban rail transit power supply voltage level and the actual requirements of the new rail transit; The second main module is used to design the new urban rail transit power supply system according to the initially determined new traction power supply voltage level; The third main module analyzes and verifies the power supply capacity and power supply radius of the new urban rail transit power supply system, and optimizes the voltage level parameters according to the verification results.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, This computer program is executed by a processor to implement the method for designing the voltage level of the urban rail transit power supply system based on AC 3 kV according to any one of claims 1 - 8.

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