Method and system for calculating the interconnection service capability of a flexible interconnection device of a medium voltage network
Patent Information
- Application Number
- CN202610769164.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-31
- Publication Date
- 2026-09-15
Smart Images
Figure CN122763431A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power network technology, and more specifically, relates to a method and system for calculating the mutual support capability of flexible interconnection devices in medium-voltage networks. Background Technology
[0002] The urban rail transit power supply system is a core infrastructure that ensures stable power supply for the traction and station power and lighting loads of rail transit vehicles such as subways and light rails. Currently, the mainstream system adopts a 35kV medium-voltage ring network power supply architecture, with centralized or decentralized main substations providing zoned power supply as the main form. It undertakes the task of continuously supplying power to traction loads and power and lighting loads, and is gradually connecting to new energy sources such as distributed photovoltaics in vehicle depots and parking lots. It is a key link in supporting the safe, efficient and green operation of rail transit.
[0003] Traditional rail transit power supply systems generally adopt a zoned independent power supply and hard tie switch isolation operation mode. Each main substation corresponds to an independent power supply zone. During normal operation, the inter-zone tie circuit breaker is in the open state. Only when the main substation is faulty or under maintenance can the limited load be transferred by manually operating the hard tie switch. External power sources need to be configured with redundancy based on the maximum load of a single main substation. Distributed photovoltaic power can only be consumed locally and cannot achieve flexible power control and capacity sharing across power supply zones.
[0004] The aforementioned traditional power supply mode has obvious defects: First, external power sources need to be redundantly configured, the investment in building new main substations is high and the site selection is difficult, the existing power reserve capacity cannot be used across regions, and the equipment utilization rate is low; Second, the output of distributed photovoltaic power is intermittent and fluctuates, and curtailment is likely to occur when the local absorption capacity is insufficient, and there is a lack of cross-regional absorption technology; Third, in the event of a fault or maintenance, manual switching of power supply is relied upon by hard switches, which has a slow response speed and poor power supply continuity, making it difficult to meet the high reliability power supply requirements of rail transit. Summary of the Invention
[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method and system for calculating the mutual support capacity of flexible interconnection devices in medium-voltage networks. It integrates rail transit power supply topology, external power source operation data, load and photovoltaic timing characteristics, constructing a complete technical system from data acquisition, capacity calculation, power calculation to device configuration and control strategy generation. The overall system achieves integrated design of flexible power mutual support between power supply zones and cross-regional coordinated absorption of distributed photovoltaic power, providing a complete solution for the planning, equipment selection, and operation control of flexible interconnected power supply systems for rail transit, comprehensively improving the system's overall operational comprehensiveness and engineering practicality.
[0006] To achieve the above objectives, according to a first aspect of the present invention, a method for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network is provided, comprising the following steps: S100. Obtain network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; S200: Collects real-time operating data from various external power sources, including load rate, backup capacity, and status of upstream power supply. S300. Based on the existing capacity of external power sources, calculate the mutual power support capability of the flexible interconnection device in different power supply intervals. S400. Based on the photovoltaic power output forecast data and load forecast data, calculate the feasible range for photovoltaic power to cross power supply zones for consumption. S500. Based on mutual support capability and absorption range, determine the rated power configuration, installation location and system wiring scheme of the flexible interconnection device; S600 generates power mutual assistance control commands based on the determined configuration scheme, driving the flexible interconnect device to perform cross-zone power transmission.
[0007] Further, in step S300, it is necessary to calculate the available reserve capacity of the external power supply at the sending end and the maximum required capacity of the external power supply at the receiving end. Based on the difference between the available reserve capacity and the maximum required capacity, the long-term power mutual assistance power of the flexible interconnection device in different power supply intervals is calculated and determined.
[0008] Furthermore, the available reserve capacity at the sending end is obtained by subtracting the maximum load capacity that the sending end's external power supply must retain, with the maximum output capacity as the upper limit. Specifically: , in, For the available spare capacity at the sending end, This represents the maximum transmittable capacity of the external power supply at the transmitting end. This is the maximum capacity required by the sending end itself; Considering both single-line and dual-line power supply scenarios, the maximum required capacity of the external power supply at the receiving end is calculated. When the constraints are met: At that time, the long-term mutual assistance power is equal to the receiving end gap capacity, that is: , in, For long-term mutual power, This represents the maximum capacity that the external power supply can deliver to the receiving end.
[0009] Furthermore, in a single-line power supply scenario, the maximum required capacity of the external power supply at the receiving end... for: , In a dual-line power supply scenario, the maximum required capacity of the external power supply at the receiving end is... for: , in, , The capacity required for the normal operation of lines 1 and 2 , The maximum capacity required to handle faults in lines 1 and 2; Maximum required capacity for failure regardless of the scenario It is necessary to consider scenarios where the upstream power supply of this power point fails, as well as the maximum capacity to support other power points.
[0010] Furthermore, it is necessary to first obtain photovoltaic power output forecast data and full power supply zone load forecast data within a preset period. Based on the power change characteristics of urban rail transit traction load, which include second-level rapid fluctuations, short-term peak impacts, and random fluctuations, the photovoltaic power output and local zone load are matched and compared point by point on a second-level time scale. Continuous or discrete time periods in which the real-time predicted photovoltaic power output is greater than the real-time absorption capacity of the local zone are selected. Within this time period, using the second-level power sampling value as the calculation benchmark, the real-time photovoltaic power output is subtracted from the real-time absorbable load power of the local zone to obtain the excess photovoltaic power at that moment, and a full-cycle excess photovoltaic power sequence is formed according to the time series. Let the time step be In the time interval Inside: , , in: To predict the photovoltaic output at time t, Let the local zone load be at time t. For photovoltaic power output time series prediction function, For local zone load time-series forecasting functions, , For the prediction model parameter vector; The set of times when photovoltaic output exceeds local consumption capacity is: , The excess photovoltaic power is: , When calculating excess photovoltaic power, the effective value or peak value within the statistical window is used to characterize the overall excess level: , , in, This represents the average excess photovoltaic power during periods of photovoltaic surplus. This represents the total number of sampling points per second during periods of photovoltaic oversupply. This represents the maximum excess photovoltaic power during the period of photovoltaic surplus.
[0011] Furthermore, when calculating excess photovoltaic power, second-level load forecast data for remote zones is acquired simultaneously and time-series aligned with the same time scale and sampling step size. For each moment within the photovoltaic excess period, the excess photovoltaic power at that moment is matched and compared in real time with the load that the remote zone can absorb at the same moment. With the constraint of not exceeding the actual absorption capacity of the remote zone, the smaller value between the excess photovoltaic power and the load of the remote zone is taken as the instantaneous peak mutual assistance power that the flexible interconnection device can carry at that moment. During the entire photovoltaic excess period, the maximum value among all instantaneous peak mutual assistance powers is taken as the peak mutual assistance power of the flexible interconnection device. With this peak mutual assistance power as the upper limit, combined with the photovoltaic output time sequence, the local and remote zone load time sequence, and device transmission constraints, the power range, time range, and transmission capacity upper limit of photovoltaic power that can be transmitted and absorbed across power supply zones are determined. Finally, the feasible range of photovoltaic power that can be absorbed across power supply zones is quantified. Load power of remote zones for: , in, To extend the time-series load forecasting function for different zones, To extend the parameter vector of the regional load forecasting model; The smaller of the excess photovoltaic power and the remote load is : , The rated peak mutual assistance power of the flexible interconnection device is: , The feasible range for the photovoltaic power to be transmitted and consumed across power supply zones is as follows: For photovoltaic power to cross regional feasible consumption zones, This refers to the actual photovoltaic power that can be transmitted across regions.
[0012] Furthermore, in step S500, based on the long-term power mutual assistance capability between power supply sections determined in step S300 and the cross-regional absorption range of photovoltaic power determined in step S400, the rated power configuration, installation location and system wiring scheme of the flexible interconnection device need to be determined as a whole, taking into account the system power supply topology, external power supply capacity constraints, cable transmission capacity, power supply zone boundary conditions and the timing characteristics of rail transit load and photovoltaic output. First, based on the distribution of the main substation, switching station, traction step-down hybrid substation and step-down substation, the division of power supply zones, the connection form of medium voltage bus, site space conditions and power transmission path loss, the optimal installation location of the flexible interconnection device is determined, and then the rated power of the flexible interconnection device is calculated. The rated power of the flexible interconnection device is calculated according to a preset rule, namely: first, the determined long-term mutual assistance power value and the one-third conversion value of the peak mutual assistance power are extracted respectively; then, the long-term mutual assistance power and the one-third conversion value of the peak mutual assistance power are compared, and the larger value of the two is selected as the base power value; the base power value is multiplied by the system's preset capacity margin coefficient to obtain the rated power of the flexible interconnection device. After determining the rated power, and based on the rated power level, installation location, voltage level of the power supply zones on both sides, and busbar structure, determine the system wiring scheme for the flexible interconnection device and the medium-voltage power supply network.
[0013] Furthermore, the rated power of the flexible interconnect device is: in, Preset a capacity margin factor for the system. For long-term mutual power, This represents the peak mutual assistance power.
[0014] Furthermore, step S600 specifically includes: Based on the determined rated power and system wiring scheme, when the load of a certain power supply zone is detected to exceed the preset threshold, the direction of power transfer from the power supply zone with a lower load rate to the power supply zone with a higher load rate is determined, and the photovoltaic absorption of nearby zones is prioritized. Then, a power mutual assistance control command is generated to drive the flexible interconnection device to perform cross-zone power transfer.
[0015] According to a second aspect of the present invention, a system for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network is provided, comprising: The first data module is used to acquire network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; The second data module is used to collect real-time operating data from each external power source, including load rate, standby capacity, and status of upstream power supply. Capacity Calculation Module: Used to calculate the mutual power support capability of flexible interconnection devices in different power supply sections based on the existing capacity of external power sources. Range calculation module: used to calculate the feasible range for photovoltaic power to cross power supply zones and be consumed based on photovoltaic output forecast data and load forecast data; Solution determination module: used to determine the rated power configuration, installation location and system wiring scheme of flexible interconnection devices based on mutual support capacity and absorption range; Command transmission module: Used to generate power mutual assistance control commands according to the determined configuration scheme, and drive the flexible interconnection device to perform cross-zone power transmission.
[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The flexible interconnection device mutual support capacity calculation method of the present invention integrates the rail transit power supply topology, external power supply operation data, load and photovoltaic timing characteristics, and constructs a complete technical system from data acquisition, capacity calculation, power calculation to device configuration and control strategy generation. It achieves integrated design of flexible power mutual support between power supply zones and cross-regional coordinated absorption of distributed photovoltaic power, providing a complete solution for the planning, equipment selection and operation control of rail transit flexible interconnection power supply systems, and comprehensively improving the system's overall operation and engineering practicality.
[0017] 2. The flexible interconnection device mutual support capability calculation method of the present invention relies on comprehensive collection and analysis of power supply network topology and external power supply operation status to accurately calculate the power supply capacity and carrying capacity of each power supply zone, and rationally utilize existing external power supply reserve resources. It breaks down the barriers of traditional independent power supply to different zones, realizing resource sharing and complementarity of power supply capacity in different zones, without the need for excessive addition of transformer equipment and external power supply capacity configuration, effectively saving investment in rail transit power supply system construction and land resource occupation.
[0018] 3. The method for calculating the mutual support capacity of the flexible interconnection device of the present invention combines the second-level fluctuation characteristics of rail transit traction load with the prediction law of photovoltaic power output to accurately identify excess photovoltaic power and reasonably delineate the feasible range for cross-regional consumption. This breaks through the limitation that photovoltaic power can only be consumed locally, fully utilizes the off-site and zoned loads to absorb surplus photovoltaic power, significantly reduces distributed photovoltaic curtailment, improves the utilization rate of new energy, and helps the rail transit power supply system achieve the goal of low-carbon and energy-saving operation.
[0019] 4. The flexible interconnection device mutual support capability calculation method of the present invention rationally configures the rated power, installation location, and wiring scheme of the flexible interconnection device by comprehensively considering long-term mutual support needs and photovoltaic peak mutual support needs, and forms a matching intelligent power mutual support control logic. It can automatically adjust the power flow direction according to the regional load fluctuations, prioritize the local photovoltaic consumption, realize rapid power support under fault and heavy load conditions, and significantly improve the stability, reliability, and dynamic load adaptability of the power supply system. Attached Figure Description
[0020] Figure 1 This is a flowchart illustrating a method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a system wiring scheme calculated by a method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to an embodiment of the present invention. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0022] Example 1 like Figure 1 As shown, this embodiment of the invention provides a method for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network, specifically including the following steps: S100. Obtain network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; S200: Collects real-time operating data from various external power sources, including load rate, backup capacity, and status of upstream power supply. S300. Based on the existing capacity of external power sources, calculate the mutual power support capability of the flexible interconnection device in different power supply intervals. S400. Based on the photovoltaic power output forecast data and load forecast data, calculate the feasible range for photovoltaic power to cross power supply zones for consumption. S500. Based on mutual support capability and absorption range, determine the rated power configuration, installation location and system wiring scheme of the flexible interconnection device; S600 generates power mutual assistance control commands based on the determined configuration scheme, driving the flexible interconnect device to perform cross-zone power transmission.
[0023] Step S100 specifically involves: comprehensively acquiring the medium-voltage network topology data of the target city's rail transit power supply system through methods such as on-site data collection, retrieval of design drawings, and querying of operational databases. This includes: the geographical location of each main substation, the capacity of the main transformer, the wiring configuration of the medium-voltage busbar, and the power supply coverage area; the location of each switching station, the configuration of incoming and outgoing circuits, the transfer capacity, and the range of the power supply zones it serves; the installation location of each traction step-down hybrid substation, the capacity of the traction rectifier unit, the capacity of the step-down transformer, the power supply radius, and the power supply zone affiliation; and the location of each step-down substation, the capacity of the step-down transformer, the type of power supply load, and the power supply service area. Through the complete acquisition of the above data, the equipment distribution, electrical connection relationships, capacity configuration, and zone boundaries of the entire rail transit power supply system are clarified, providing fundamental topology support for subsequent power mutual assistance capacity calculations and photovoltaic absorption range analysis.
[0024] In step S200, real-time operating status data of all external power sources along the entire line is obtained through real-time acquisition and historical data adjustment of the power monitoring system and the acquisition of CT / PT information in the local switch cabinet. Specifically, this includes: the real-time load rate, rated power supply capacity and current actual output power, and long-term operating load level of each external power source; the real-time backup capacity that each external power source can support externally under the premise of meeting the safe and stable operation of its own power supply zone, and the effective backup capacity considering N-1 faults, equipment overload, and cable thermal stability constraints; at the same time, relevant information of the superior power source to which each external power source belongs is collected, including the name of the superior power source site, voltage level, main wiring form, capacity configuration, power supply reliability level, line impedance and transmission capacity, as well as the operation mode, maintenance plan and power supply constraints of the superior power grid, providing a real and complete operating data source for subsequent mutual support capacity calculation, power balance analysis and safety verification.
[0025] In step S300, based on the actual existing capacity and safe operation constraints of the existing external power sources in the urban rail transit power supply system, capacity calculations are performed for the sending and receiving external power sources of the power transmission: First, the available standby capacity that the sending external power source can provide external support is calculated after deducting its maximum load capacity, provided that the safe and reliable operation of its own power supply zone is ensured and N-1 fault redundancy and equipment safety margin are met. Then, the maximum required capacity of the receiving external power source is calculated under typical operating conditions such as normal operation, single power source failure, and cross-line support to ensure continuous and stable power supply to its power supply zone. Under the constraint that the sum of the available standby capacity of the sending end and the maximum power supply capacity of the receiving end can meet the maximum required capacity of the receiving end, the long-term mutual assistance power required by the flexible interconnection device to perform long-term, stable power mutual assistance between power supply zones of different main substations is calculated and finally determined using the difference between the maximum required capacity of the receiving end and the maximum power supply capacity of the receiving end.
[0026] In step S300, it is necessary to calculate the available reserve capacity of the external power supply at the sending end and the maximum required capacity of the external power supply at the receiving end. Based on the difference between the available reserve capacity and the maximum required capacity, the long-term power mutual assistance power of the flexible interconnection device in different power supply intervals is calculated and determined.
[0027] The available reserve capacity at the sending end is obtained by subtracting the maximum load capacity that the sending end must retain, with the maximum output capacity of the external power supply as the upper limit. Specifically: , in, For the available spare capacity at the sending end, This represents the maximum transmittable capacity of the external power supply at the transmitting end. This is the maximum capacity required by the sending end itself; Considering both single-line and dual-line power supply scenarios, the maximum required capacity of the external power supply at the receiving end is calculated. When the constraints are met: At that time, the long-term mutual assistance power is equal to the receiving end gap capacity, that is: , in, For long-term mutual power, This represents the maximum capacity that the external power supply can deliver to the receiving end.
[0028] In a single-line power supply scenario, the maximum required capacity of the external power supply at the receiving end is... for: , In a dual-line power supply scenario, the maximum required capacity of the external power supply at the receiving end is... for: , in, , The capacity required for the normal operation of lines 1 and 2 , The maximum capacity required to handle faults in lines 1 and 2; Maximum required capacity for failure regardless of the scenario It is necessary to consider scenarios where the upstream power supply of this power point fails, as well as the maximum capacity to support other power points.
[0029] In step S400, it is necessary to first obtain the photovoltaic power output prediction data and the load prediction data of the entire power supply zone within the preset period. Based on the power change characteristics of urban rail transit traction load, which are characterized by rapid fluctuations at the second level, short-term peak impacts, and random fluctuations, the photovoltaic power output and the local zone load are matched and compared point by point at the second-level time scale. The continuous or discrete time periods in which the real-time predicted photovoltaic power output is greater than the real-time absorption capacity of the local zone are selected. Within this time period, the real-time photovoltaic power output is subtracted from the real-time absorbable load power of the local zone based on the second-level power sampling value to obtain the excess photovoltaic power at this moment. The excess photovoltaic power sequence of the entire period is then formed according to the time series. Let the time step be In the time interval Inside: , , in: To predict the photovoltaic output at time t, Let the local zone load be at time t. For photovoltaic power output time series prediction function, For local zone load time-series forecasting functions, , For the prediction model parameter vector; The set of times when photovoltaic output exceeds local consumption capacity is: , The excess photovoltaic power is: , When calculating excess photovoltaic power, the effective value or peak value within the statistical window is used to characterize the overall excess level: , , in, This represents the average excess photovoltaic power during periods of photovoltaic surplus. This represents the total number of sampling points per second during periods of photovoltaic oversupply. This represents the maximum excess photovoltaic power during the period of photovoltaic surplus.
[0030] When calculating excess photovoltaic power, second-level load forecast data of remote zones are acquired simultaneously and time-series aligned with the same time scale and sampling step size. For each moment within the photovoltaic excess period, the excess photovoltaic power at that moment is matched and compared with the load that the remote zone can absorb at the same moment in real time. With the constraint of not exceeding the actual absorption capacity of the remote zone, the smaller value between the excess photovoltaic power and the load of the remote zone is taken as the instantaneous peak mutual assistance power that the flexible interconnection device can carry at that moment. During the entire photovoltaic excess period, the maximum value among all instantaneous peak mutual assistance powers is taken as the peak mutual assistance power of the flexible interconnection device. With this peak mutual assistance power as the upper limit, combined with the photovoltaic output time sequence, the local and remote zone load time sequence, and device transmission constraints, the power range, time range, and transmission capacity upper limit of photovoltaic power that can be transmitted and absorbed across power supply zones are determined. Finally, the feasible range of photovoltaic power crossing power supply zones for absorption is quantified. Load power of remote zones for: , in, To extend the time-series load forecasting function for different zones, To extend the parameter vector of the regional load forecasting model; The smaller of the excess photovoltaic power and the remote load is : , The rated peak mutual assistance power of the flexible interconnection device is: , The feasible range for the photovoltaic power to be transmitted and consumed across power supply zones is as follows: For photovoltaic power to cross regional feasible consumption zones, This refers to the actual photovoltaic power that can be transmitted across regions.
[0031] In step S500, based on the long-term power mutual assistance capability between power supply sections determined in step S300 and the cross-regional absorption range of photovoltaic power determined in step S400, the rated power configuration, installation location and system wiring scheme of the flexible interconnection device need to be determined as a whole, taking into account the system power supply topology, external power supply capacity constraints, cable transmission capacity, power supply zone boundary conditions and the timing characteristics of rail transit load and photovoltaic output.
[0032] First, based on the distribution locations of the main substation, switching station, traction step-down hybrid substation and step-down substation, the power supply zone division, the medium-voltage bus connection form, site space conditions and power transmission path loss, the optimal installation location of the flexible interconnection device is determined, and then the rated power of the flexible interconnection device is calculated.
[0033] The rated power of the flexible interconnection device is calculated according to a preset rule, namely: first, the determined long-term mutual assistance power value and the one-third conversion value of the peak mutual assistance power are extracted respectively; then, the long-term mutual assistance power and the one-third conversion value of the peak mutual assistance power are compared, and the larger value is selected as the base power value; the base power value is multiplied by the system's preset capacity margin coefficient to obtain the rated power of the flexible interconnection device.
[0034] After determining the rated power, and based on the rated power level, installation location, voltage level of the power supply zones on both sides, and busbar structure, determine the system wiring scheme for the flexible interconnection device and the medium-voltage power supply network.
[0035] The rated power of the flexible interconnect device is: in, Preset a capacity margin factor for the system. For long-term mutual power, This represents the peak mutual assistance power.
[0036] Step S600 is as follows: Based on the determined rated power and system wiring scheme, when the load of a certain power supply zone is detected to exceed the preset threshold, the direction of power transfer from the power supply zone with a lower load rate to the power supply zone with a higher load rate is determined, and the photovoltaic absorption of nearby zones is prioritized. Then, a power mutual assistance control command is generated to drive the flexible interconnection device to perform cross-zone power transfer.
[0037] like Figure 2 As shown, in a preferred embodiment of the present invention, the system wiring scheme determined by calculation includes: The first main substation has a first 35kV medium-voltage busbar, which supplies power to multiple power supply zones; The second main substation has a second 35kV medium-voltage busbar and supplies power to multiple power supply zones. The upstream 220kV external power sources of the first and second main substations are different; The flexible interconnect device includes a first voltage source converter and a second voltage source converter; The AC side of the first voltage source converter is connected to the first 35kV medium voltage bus, and the AC side of the second voltage source converter is connected to the second 35kV medium voltage bus. The DC sides of the first voltage source converter and the second voltage source converter are interconnected via a common DC bus; The flexible interconnection device enables bidirectional power flow between the power supply zones of the first and second main substations.
[0038] Example 2 This invention provides a system for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network, comprising: The first data module is used to acquire network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; The second data module is used to collect real-time operating data from each external power source, including load rate, standby capacity, and status of upstream power supply. Capacity Calculation Module: Used to calculate the mutual power support capability of flexible interconnection devices in different power supply sections based on the existing capacity of external power sources. Range calculation module: used to calculate the feasible range for photovoltaic power to cross power supply zones and be consumed based on photovoltaic output forecast data and load forecast data; Solution determination module: used to determine the rated power configuration, installation location and system wiring scheme of flexible interconnection devices based on mutual support capacity and absorption range; Command transmission module: Used to generate power mutual assistance control commands according to the determined configuration scheme, and drive the flexible interconnection device to perform cross-zone power transmission.
[0039] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for calculating the flexible interconnection device mutual assistance capability of a medium voltage network, characterized in that, Includes the following steps: S100. Obtain network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; S200: Collects real-time operating data from various external power sources, including load rate, backup capacity, and status of upstream power supply. S300. Based on the existing capacity of external power sources, calculate the mutual power support capability of the flexible interconnection device in different power supply intervals. S400. Based on the photovoltaic power output forecast data and load forecast data, calculate the feasible range for photovoltaic power to cross power supply zones for consumption. S500. Based on mutual support capability and absorption range, determine the rated power configuration, installation location and system wiring scheme of the flexible interconnection device; S600 generates power mutual assistance control commands based on the determined configuration scheme, driving the flexible interconnect device to perform cross-zone power transmission.
2. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 1, characterized in that, In step S300, it is necessary to calculate the available reserve capacity of the external power supply at the sending end and the maximum required capacity of the external power supply at the receiving end. Based on the difference between the available reserve capacity and the maximum required capacity, the long-term power mutual assistance power of the flexible interconnection device in different power supply intervals is calculated and determined.
3. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 2, characterized in that, The available reserve capacity at the sending end is obtained by subtracting the maximum load capacity that the sending end must retain, with the maximum output capacity of the external power supply as the upper limit. Specifically: ， in, For the available spare capacity at the sending end, This represents the maximum transmittable capacity of the external power supply at the transmitting end. This is the maximum capacity required by the sending end itself; Considering both single-line and dual-line power supply scenarios, the maximum required capacity of the external power supply at the receiving end is calculated. When the constraints are met: At that time, the long-term mutual assistance power is equal to the receiving end gap capacity, that is: ， in, For long-term mutual power, This represents the maximum capacity that the external power supply can deliver to the receiving end.
4. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 3, characterized in that, In a single-line power supply scenario, the maximum required capacity of the external power supply at the receiving end is... for: ， In a dual-line power supply scenario, the maximum required capacity of the external power supply at the receiving end is... for: ， in, , The capacity required for the normal operation of lines 1 and 2 , The maximum capacity required to handle faults in lines 1 and 2; Maximum required capacity for failure regardless of the scenario It is necessary to consider scenarios where the upstream power supply of this power point fails, as well as the maximum capacity to support other power points.
5. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 4, characterized in that, In step S400, it is necessary to first obtain the photovoltaic power output prediction data and the load prediction data of the entire power supply zone within the preset period. Based on the power change characteristics of urban rail transit traction load, which are characterized by rapid fluctuations at the second level, short-term peak impacts, and random fluctuations, the photovoltaic power output and the local zone load are matched and compared point by point at the second-level time scale. The continuous or discrete time periods in which the real-time predicted photovoltaic power output is greater than the real-time absorption capacity of the local zone are selected. Within this time period, the real-time photovoltaic power output is subtracted from the real-time absorbable load power of the local zone based on the second-level power sampling value to obtain the excess photovoltaic power at this moment. The excess photovoltaic power sequence of the entire period is then formed according to the time series. Let the time step be In the time interval Inside: ， ， in: To predict the photovoltaic output at time t, Let the local zone load be at time t. For photovoltaic power output time series prediction function, For local zone load time-series forecasting functions, , For the prediction model parameter vector; The set of times when photovoltaic output exceeds local consumption capacity is: ， The excess photovoltaic power is: ， When calculating excess photovoltaic power, the effective value or peak value within the statistical window is used to characterize the overall excess level: ， ， in, This represents the average excess photovoltaic power during periods of photovoltaic surplus. This represents the total number of sampling points per second during periods of photovoltaic oversupply. This represents the maximum excess photovoltaic power during the period of photovoltaic surplus.
6. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 5, characterized in that, When calculating excess photovoltaic power, second-level load forecast data of remote zones are acquired simultaneously and time-series aligned with the same time scale and sampling step size. For each moment within the photovoltaic excess period, the excess photovoltaic power at that moment is matched and compared with the load that the remote zone can absorb at the same moment in real time. With the constraint of not exceeding the actual absorption capacity of the remote zone, the smaller value between the excess photovoltaic power and the load of the remote zone is taken as the instantaneous peak mutual assistance power that the flexible interconnection device can carry at that moment. During the entire photovoltaic excess period, the maximum value among all instantaneous peak mutual assistance powers is taken as the peak mutual assistance power of the flexible interconnection device. With this peak mutual assistance power as the upper limit, combined with the photovoltaic output time sequence, the local and remote zone load time sequence, and device transmission constraints, the power range, time range, and transmission capacity upper limit of photovoltaic power that can be transmitted and absorbed across power supply zones are determined. Finally, the feasible range of photovoltaic power crossing power supply zones for absorption is quantified. Load power of remote zones for: ， in, To extend the time-series load forecasting function for different zones, To extend the parameter vector of the regional load forecasting model; The smaller of the excess photovoltaic power and the remote load is : ， The rated peak mutual assistance power of the flexible interconnection device is: ， The feasible range for the photovoltaic power to be transmitted and consumed across power supply zones is as follows: ， For photovoltaic power to cross regional feasible consumption zones, This refers to the actual photovoltaic power that can be transmitted across regions.
7. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 6, characterized in that, In step S500, based on the long-term power mutual assistance capability between power supply sections determined in step S300 and the cross-regional absorption range of photovoltaic power determined in step S400, the rated power configuration, installation location and system wiring scheme of the flexible interconnection device need to be determined as a whole, taking into account the power supply topology of the system, external power supply capacity constraints, cable transmission capacity, power supply zone boundary conditions and the timing characteristics of rail transit load and photovoltaic output. First, based on the distribution of the main substation, switching station, traction step-down hybrid substation and step-down substation, the division of power supply zones, the connection form of medium voltage bus, site space conditions and power transmission path loss, the optimal installation location of the flexible interconnection device is determined, and then the rated power of the flexible interconnection device is calculated. The rated power of the flexible interconnection device is calculated according to a preset rule, namely: first, the determined long-term mutual assistance power value and the one-third conversion value of the peak mutual assistance power are extracted respectively; then, the long-term mutual assistance power and the one-third conversion value of the peak mutual assistance power are compared, and the larger value of the two is selected as the base power value; the base power value is multiplied by the system's preset capacity margin coefficient to obtain the rated power of the flexible interconnection device. After determining the rated power, and based on the rated power level, installation location, voltage level of the power supply zones on both sides, and busbar structure, determine the system wiring scheme for the flexible interconnection device and the medium-voltage power supply network.
8. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 7, characterized in that, The rated power of the flexible interconnect device is: ， in, Preset a capacity margin factor for the system. For long-term mutual power, This represents the peak mutual assistance power.
9. The method for calculating the mutual support capability of a flexible interconnection device in a medium-voltage network according to claim 8, characterized in that, Step S600 is as follows: Based on the determined rated power and system wiring scheme, when the load of a certain power supply zone is detected to exceed the preset threshold, the direction of power transfer from the power supply zone with a lower load rate to the power supply zone with a higher load rate is determined, and the photovoltaic absorption of nearby zones is prioritized. Then, a power mutual assistance control command is generated to drive the flexible interconnection device to perform cross-zone power transfer.
10. A system for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network, used to implement the method for calculating the mutual support capability of flexible interconnection devices in a medium-voltage network as described in any one of claims 1-9, characterized in that, include: The first data module is used to acquire network topology data of the urban rail transit power supply system, including the location, capacity and power supply range of main substations, switching stations, traction stations and step-down stations; The second data module is used to collect real-time operating data from each external power source, including load rate, standby capacity, and status of upstream power supply. Capacity Calculation Module: Used to calculate the mutual power support capability of flexible interconnection devices in different power supply sections based on the existing capacity of external power sources. Range calculation module: used to calculate the feasible range for photovoltaic power to cross power supply zones and be consumed based on photovoltaic output forecast data and load forecast data; Solution determination module: used to determine the rated power configuration, installation location and system wiring scheme of flexible interconnection devices based on mutual support capacity and absorption range; Command transmission module: Used to generate power mutual assistance control commands according to the determined configuration scheme, and drive the flexible interconnection device to perform cross-zone power transmission.