A three-dimensional DC hub substation operation control method, system and equipment

Abstract

The present invention provides a method, system and device for operating and controlling a three-dimensional DC hub substation, including: the three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port and an AC busbar, including: determining an operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation; in the operation mode corresponding to the operation scenario, determining the control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails. The present invention realizes the interconnection of multi-voltage-level DC lines of high-proportion new energy - power grid - load through flexible and stable control of the power and voltage of the high-voltage DC port, medium-voltage DC port and standby AC port.

Description

Technical Field

[0001] The present invention relates to the technical field of DC substations and DC power transmission, and particularly relates to an operation control method, system and equipment for a three-dimensional DC hub substation. Background Art

[0002] With the continuous increase in the proportion of renewable energy connected to the power grid, traditional AC power grids face many limitations in carrying a high proportion of new energy, such as weak thermal power support, insufficient short-circuit capacity, and limited voltage regulation ability. Due to the absence of reactive power and voltage problems, DC power transmission technology has shown a rapid growth trend in the generation, transmission, distribution, and use of power systems. On the generation side, demonstration projects of all-DC integration projects for new energy such as photovoltaic and wind power have been carried out. On the transmission side, demonstration projects of multi-terminal DC power transmission projects have been carried out. On the distribution side, demonstration projects of DC distribution networks and DC interconnection projects in substations have been carried out. On the user side, DC data centers, DC industrial parks, and integrated photovoltaic energy storage and charging stations have also developed rapidly.

[0003] Since the existing substations are AC substations at present, DC application scenarios, including all-DC integration scenarios for new energy on the generation side, long-distance power transmission scenarios on the transmission side, and DC load power supply scenarios on the distribution side, all need to go through direct-AC conversion, access AC substations of corresponding voltage levels, and then be interconnected with the large power grid, which reduces the overall system operation and transmission efficiency of DC generation - DC power transmission - DC distribution - DC power consumption. At the same time, it is easy to generate a large number of randomly connected AC-DC nodes in AC substations, increasing the difficulty of power grid regulation and potential safety and stability operation hazards. Summary of the Invention

[0004] In order to solve the problems that in the existing technology, DC application scenarios all need to go through direct-AC conversion, access AC substations of corresponding voltage levels, and then be interconnected with the large power grid, which reduces the overall system operation and transmission efficiency of DC generation - DC power transmission - DC distribution - DC power consumption. At the same time, it is easy to generate a large number of randomly connected AC-DC nodes in AC substations, increasing the difficulty of power grid regulation and potential safety and stability operation hazards, the present invention proposes an operation control method for a three-dimensional DC hub substation, including:

[0005] The three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including:

[0006] Based on the operation scenarios of the three-dimensional DC hub substation, determine the operation control mode corresponding to the operation scenarios;

[0007] In the operation mode corresponding to the operation scenarios, according to whether a DC line fails, determine the control mode of the DC ports of the three-dimensional DC hub substation.

[0008] Optionally, determining the operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation includes:

[0009] If the operation scenario of the three-dimensional DC hub substation is new energy collection and transmission, the new energy DC collection operation control mode is adopted; otherwise, the multi-drop DC power supply operation control mode is adopted.

[0010] Optionally, under the operation mode corresponding to the operation scenario, determining the control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails includes:

[0011] When the operation scenario corresponds to the new energy DC collection operation control mode, the power control mode of each port of the three-dimensional DC hub substation is determined by the operation control mode and the strength of the AC power grid.

[0012] When the operation scenario corresponds to the multi-drop DC power supply operation control mode, the power control mode of each port of the three-dimensional DC hub substation is determined by the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station.

[0013] Optionally, when the operation scenario corresponds to the new energy DC collection operation control mode, determining the power control mode of each port of the three-dimensional DC hub substation by the operation control mode and the strength of the AC power grid includes:

[0014] When no fault occurs, the high-voltage DC port connected to the new energy adopts the constant DC voltage operation control mode, and the high-voltage DC port connected to the DC power grid adopts the v / f operation control mode; when transient traveling waves are detected, fault identification is performed, and the mode of the high-voltage DC port corresponding to the faulty line is switched.

[0015] The medium-voltage DC port connected to the new energy adopts the control mode of constant DC voltage.

[0016] The power control mode of the standby high-voltage AC port is determined based on the strength of the local AC power grid.

[0017] Optionally, when transient traveling waves are detected, fault identification is performed, and the mode of the high-voltage DC port corresponding to the faulty line is switched, including:

[0018] When the high-voltage DC port connected to the new energy field and / or the high-voltage DC port connected to the DC power grid detects DC line traveling waves and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connected to the new energy field and the high-voltage DC port connected to the DC power grid.

[0019] The control mode of the high-voltage DC port whose identified result is the traveling wave generated by the DC short-circuit fault is switched to the fault current limiting control mode.

[0020] Optionally, when the operating scenario corresponds to the multi-drop DC power supply operation control mode, the power control modes of each port of the three-dimensional DC hub substation are determined by the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station, including:

[0021] When no fault occurs, the HVDC port adopts the v / f operation control mode; when transient traveling waves are detected, fault identification is performed to determine whether to switch the operation control mode of the HVDC port connected to the DC power grid;

[0022] Based on the control mode of the opposite converter station, determine the control mode of the medium-voltage DC port;

[0023] Based on the strength of the local AC power grid, determine the power control mode of the standby high-voltage AC port.

[0024] Optionally, the determining the control mode of the medium-voltage DC port based on the control mode of the opposite converter station includes:

[0025] If the control mode of the opposite converter station is constant DC voltage control, the medium-voltage DC port adopts a constant power operation control mode; otherwise, the medium-voltage DC port adopts a constant DC voltage operation control mode;

[0026] Optionally, the determining the power control mode of the standby high-voltage AC port based on the strength of the local AC power grid includes:

[0027] If the short-circuit ratio of the connected AC power grid is less than the set threshold, a network-forming control mode is adopted; otherwise, a constant power control mode is adopted.

[0028] Optionally, when transient traveling waves are detected, fault identification is performed to determine whether to switch the operation control mode of the HVDC port connected to the DC power grid, including:

[0029] When the HVDC port connected to the DC power grid detects DC line traveling waves and the amplitude exceeds a predetermined threshold, fault identification is performed on the HVDC port connected to the DC power grid;

[0030] When the identification result is a traveling wave generated by a DC short-circuit fault, the control mode of the HVDC port connected to the DC power grid is switched to a fault current limiting control mode.

[0031] On the other hand, the present application also provides an operation control system for a three-dimensional DC hub substation. The three-dimensional DC hub substation includes an HVDC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including:

[0032] A mode identification module, configured to determine an operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation;

[0033] A mode switching module, configured to determine a control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails under the operation mode corresponding to the operation scenario.

[0034] Optionally, the mode identification module is specifically configured to:

[0035] If the operation scenario of the three-dimensional DC hub substation is new energy collection and transmission, the new energy DC collection operation control mode is adopted; otherwise, the multi-drop DC power supply operation control mode is adopted.

[0036] Optionally, the mode switching module includes:

[0037] A first control sub-module, configured to determine a power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid when the operation scenario corresponds to the new energy DC collection operation control mode;

[0038] A second control sub-module, configured to determine a power control mode of each port of the three-dimensional DC hub substation according to the operation control mode, the strength of the AC power grid, and the control mode of the opposite-side converter station when the operation scenario corresponds to the multi-drop DC power supply operation control mode.

[0039] Optionally, the first control sub-module includes:

[0040] A first high-voltage port control unit, configured to, when no fault occurs, adopt a constant DC voltage operation control mode for the high-voltage DC port connected to the new energy, and adopt a v / f operation control mode for the high-voltage DC port connected to the DC power grid; when transient traveling waves are detected, perform fault identification and switch the mode of the high-voltage DC port corresponding to the faulty line;

[0041] A first medium-voltage port control unit, configured to adopt a control mode of constant DC voltage for the medium-voltage DC port connected to the new energy;

[0042] A first standby port control unit, configured to determine a power control mode of the standby high-voltage AC port based on the strength of the local AC power grid.

[0043] Optionally, when transient traveling waves are detected in the first high-voltage port control unit, perform fault identification and switch the mode of the high-voltage DC port corresponding to the faulty line. The specific implementation steps include:

[0044] When traveling waves on the DC line are detected at the high-voltage DC port connecting to the new energy power station and / or the high-voltage DC port connecting to the DC grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting to the new energy power station and the high-voltage DC port connecting to the DC grid;

[0045] Switch the control mode of the high-voltage DC port where the traveling wave generated by the DC short-circuit fault is identified to the fault current-limiting control mode.

[0046] Optionally, the first standby port control unit is specifically used for:

[0047] If the short-circuit ratio of the connected AC grid is less than the set threshold, the grid-forming control mode is adopted; otherwise, the constant power control mode is adopted.

[0048] Optionally, the second control sub-module is used for:

[0049] The second high-voltage port control unit is used for, when no fault occurs, the high-voltage DC port adopts the v / f operation control mode; when transient traveling waves are detected, fault identification is performed to determine whether to switch the operation control mode of the high-voltage DC port connecting to the DC grid;

[0050] The second medium-voltage port control unit is used for determining the control mode of the medium-voltage DC port based on the control mode of the opposite converter station;

[0051] The second standby port control unit is used for determining the power control mode of the standby high-voltage AC port based on the strength of the local AC grid.

[0052] Optionally, when transient traveling waves are detected in the second high-voltage port control unit, the specific implementation steps for performing fault identification to determine whether to switch the operation control mode of the high-voltage DC port connecting to the DC grid include:

[0053] When traveling waves on the DC line are detected at the high-voltage DC port connecting to the DC grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting to the DC grid;

[0054] When the identification result is a traveling wave generated by a DC short-circuit fault, switch the control mode of the high-voltage DC port connecting to the DC grid to the fault current-limiting control mode.

[0055] Optionally, the second standby port control unit is specifically used for:

[0056] If the short-circuit ratio of the connected AC grid is less than the set threshold, the grid-forming control mode is adopted; otherwise, the constant power control mode is adopted.

[0057] Optionally, the second medium-voltage port control unit is specifically used for:

[0058] If the control mode of the opposite converter station is constant DC voltage control, the medium-voltage DC port operates in a constant power control mode; otherwise, the medium-voltage DC port operates in a constant DC voltage control mode.

[0059] On the other hand, the present application also provides a computing device, including: one or more processors;

[0060] The processor is configured to execute one or more programs;

[0061] When the one or more programs are executed by the one or more processors, the method for operating and controlling a three-dimensional DC hub substation as described above is implemented.

[0062] On the other hand, the present application also provides a computer-readable storage medium with a computer program stored thereon. When the computer program is executed, the method for operating and controlling a three-dimensional DC hub substation as described above is implemented.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] The present invention provides a method for operating and controlling a three-dimensional DC hub substation, including: the three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including: determining an operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation; in the operation mode corresponding to the operation scenario, determining the control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails. By flexibly and stably controlling the power and voltage of the high-voltage DC port, medium-voltage DC port, and standby AC port, the present invention realizes the interconnection of multi-voltage-level DC lines of high-proportion new energy - power grid - load. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a flowchart of a method for operating and controlling a DC hub substation according to the present invention;

[0066] Figure 2 It is a schematic diagram of classified control of the application scenario of a three-dimensional DC hub substation according to the present invention;

[0067] Figure 3 It is a control block diagram of a new energy aggregation operation control mode according to the present invention;

[0068] Figure 4 It is a control block diagram of a multi-drop DC power supply operation control mode according to the present invention;

[0069] Figure 5 It is a schematic diagram of a three-dimensional DC hub substation according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The present invention provides a method for operating and controlling a DC hub substation, which has a "three-dimensional" characteristic. Here, the "three-dimensional" mainly reflects that the hub substation can provide AC and DC access ports of multiple voltage levels, covering high, medium, and low different series of multiple levels of DC voltages such as ±800kV, ±500kV, ±200kV, ±100kV, ±35kV, ±10kV, ±750V and all levels of AC voltages, forming a power interaction hub that can realize the convergence and access of new energy of different scales and the power supply of multi-point and multi-type AC and DC loads. Through the flexible and stable control of the power and voltage of the high-voltage DC port, medium-voltage DC port, and standby AC port of the DC hub substation, the interconnection of multi-voltage-level DC lines of high-proportion new energy-grid-load is realized. A fault traveling wave detection module is embedded in the converter control system of the DC hub substation to achieve fast current limiting for DC port faults and non-blocking fault crossing, improving the overall operation reliability of the DC hub substation.

[0071] Embodiment 1:

[0072] A method for operating and controlling a DC hub substation, as Figure 1 shown, the three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including:

[0073] Step S1: Based on the operation scenario of the three-dimensional DC hub substation, determine the operation control mode corresponding to the operation scenario;

[0074] Step S2: In the operation mode corresponding to the operation scenario, determine the control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails.

[0075] Aiming at the problems of low overall efficiency and poor operation control flexibility in the control of high-proportion new energy DC integration and multi-drop DC power supply in existing AC substations, the present invention discloses a method for operating and controlling a "three-dimensional" DC hub substation to achieve the interconnection of multi-voltage-level DC lines of high-proportion new energy-grid-load.

[0076] To achieve the above invention purpose, the present invention adopts the following method to achieve:

[0077] A method for operating and controlling a three-dimensional DC hub substation, the three-dimensional DC hub substation has an external high-voltage DC port, an external medium-voltage DC port, a standby high-voltage AC port, and an internal AC bus; the operation control method mainly includes a new energy DC integration operation control mode and a multi-drop DC power supply operation control mode according to the application scenario; the operation control method determines whether to switch to a fault current limiting control mode according to whether a DC line fails.

[0078] Step S1: Based on the operation scenario of the three-dimensional DC hub substation, determine the operation control mode corresponding to the operation scenario, as Figure 2 shown, including:

[0079] If the operation scenario of the three-dimensional DC hub substation is new energy collection and transmission, the new energy DC collection operation control mode is adopted; otherwise, the multi-drop DC power supply operation control mode is adopted.

[0080] Step S2: Under the operation mode corresponding to the operation scenario, determine the control mode of the DC ports of the three-dimensional DC hub substation according to whether a DC line fails, including:

[0081] When the operation scenario corresponds to the new energy DC collection operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid;

[0082] When the operation scenario corresponds to the multi-drop DC power supply operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station.

[0083] Further, as Figure 3 shown, when the operation scenario corresponds to the new energy DC collection operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid, including:

[0084] When no fault occurs, the high-voltage DC port connected to the new energy adopts the constant DC voltage operation control mode, and the high-voltage DC port connected to the DC power grid adopts the v / f operation control mode; when transient traveling waves are detected, perform fault identification and switch the mode of the high-voltage DC port corresponding to the faulty line;

[0085] Adopt the control mode of constant DC voltage for the medium-voltage DC port connected to the new energy;

[0086] Determine the power control mode of the standby high-voltage AC port based on the strength of the local AC power grid.

[0087] Further, when transient traveling waves are detected, perform fault identification and switch the mode of the high-voltage DC port corresponding to the faulty line, including:

[0088] When DC line traveling waves are detected at the high-voltage DC port connected to the new energy station and / or the high-voltage DC port connected to the DC power grid, and the amplitude exceeds a predetermined threshold, perform fault identification on the high-voltage DC port connected to the new energy station and the high-voltage DC port connected to the DC power grid;

[0089] Switch the control mode of the high-voltage DC port whose identified traveling wave is generated by a DC short-circuit fault to the fault current-limiting control mode.

[0090] Furthermore, as Figure 4 shown, when the operating scenario corresponds to the multi-drop DC power supply operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operating control mode, the strength of the AC power grid, and the control mode of the opposite converter station, including:

[0091] When no fault occurs, the high-voltage DC port adopts the v / f operation control mode; when transient traveling waves are detected, perform fault identification to determine whether to switch the operating control mode of the high-voltage DC port connected to the DC power grid.

[0092] Determine the control mode of the medium-voltage DC port based on the control mode of the opposite converter station;

[0093] Determine the power control mode of the standby high-voltage AC port based on the strength of the local AC power grid.

[0094] Furthermore, when transient traveling waves are detected, perform fault identification to determine whether to switch the operating control mode of the high-voltage DC port connected to the DC power grid, including:

[0095] When the high-voltage DC port connected to the DC power grid detects a DC line traveling wave and the amplitude exceeds a predetermined threshold, perform fault identification on the high-voltage DC port connected to the DC power grid;

[0096] When the identified result is a traveling wave generated by a DC short-circuit fault, switch the control mode of the high-voltage DC port connected to the DC power grid to the fault current-limiting control mode.

[0097] Furthermore, determine the control mode of the medium-voltage DC port based on the control mode of the opposite converter station, including:

[0098] If the control mode of the opposite converter station is constant DC voltage control, the medium-voltage DC port adopts the constant power operation control mode; otherwise, the medium-voltage DC port adopts the constant DC voltage operation control mode.

[0099] Furthermore, the determination of the power control mode of the standby high-voltage AC port based on the strength of the local AC power grid includes:

[0100] If the short-circuit ratio of the connected AC power grid is less than the set threshold, adopt the network-forming control mode; otherwise, adopt the constant power control mode.

[0101] The specific content of step S2 is as follows:

[0102] A three-dimensional DC hub substation, asFigure 5 As shown, when its operation control works in the new - energy DC collection operation control mode, the external medium - voltage DC port is connected to the new - energy power station, the external high - voltage DC port (non - highest - voltage - level port) is connected to the new - energy power station, the external high - voltage DC port (highest - voltage - level port) is connected to the high - voltage DC line or the DC grid, and the standby high - voltage AC port is connected to the nearby AC grid;

[0103] For a three - dimensional DC hub substation, when its operation control works in the new - energy DC collection operation control mode, the external high - voltage DC port (non - highest - voltage - level port) adopts constant DC voltage control to control the DC voltage of the new - energy collection line, the external high - voltage DC port (highest - voltage - level port) adopts v / f control to generate and control the internal AC bus voltage, and the external medium - voltage DC port adopts constant DC voltage control to control the DC voltage of the new - energy collection line.

[0104] For a three - dimensional DC hub substation, when its operation control works in the new - energy DC collection operation control mode, according to the power quality of the internal AC bus voltage, it automatically switches between the PI double - closed - loop control mode and the model - predictive control to achieve v / f control; the specific implementation process is as follows:

[0105] When using PI double - closed - loop control, generally, the response speed of the voltage outer loop is much lower than that of the current inner loop. When the high - voltage DC port is used to connect a large - scale new - energy source, the large - scale fluctuation of new - energy power easily causes the deterioration of the internal AC voltage quality of the DC hub substation. This application proposes a dual - control mode of PI double - closed - loop / model - predictive control. Under normal conditions, the PI double - closed - loop control mode is used for v / f control. When the internal AC voltage quality of the DC hub substation deteriorates, it automatically switches from PI double - closed - loop control to model - predictive control to improve the internal AC voltage quality;

[0106] For a three - dimensional DC hub substation, when its operation control works in the multi - drop DC power supply operation control mode, the external medium - voltage DC port is connected to the medium - voltage DC distribution system, the external high - voltage DC port is connected to the high - voltage DC grid, and the standby high - voltage AC port is connected to the high - voltage AC grid;

[0107] For a three - dimensional DC hub substation, when its operation control works in the multi - drop DC power supply operation control mode, at least one of the control modes of the opposite - side converter station connected to the external high - voltage DC port (corresponding to the highest - voltage - level port) should be constant DC voltage control, and the control mode of the external high - voltage DC port (corresponding to the highest - voltage - level port) adopts v / f control to generate and control the internal AC bus voltage;

[0108] A three-dimensional DC hub substation, when its operation control works in the multi-drop DC power supply operation control mode, the control mode of the external medium-voltage DC port is determined according to the control mode of the connected converter station on the opposite side. When the control mode of the connected converter station on the opposite side is constant DC voltage control, the control mode of the external medium-voltage DC port adopts constant power control. When the control mode of the connected converter station on the opposite side is constant power control, the control mode of the external medium-voltage DC port adopts constant DC voltage control;

[0109] The identification of high-voltage DC line faults is realized through the fault traveling wave detection module embedded in the converter control system of the high-voltage DC port. When the embedded fault traveling wave detection module detects a traveling wave on the DC line and its amplitude exceeds a predetermined threshold, it enters the fault identification program. The fault identification program determines whether the traveling wave is generated by line disturbances such as lightning strikes and switch operations, or by DC short-circuit faults. If it is determined that the traveling wave is generated by a DC short-circuit fault, a fault trigger signal is quickly sent to the converter control system of the high-voltage DC port, and the control mode of the high-voltage DC port converter is switched to the fault current limiting control mode. If it is determined that the traveling wave is generated by a disturbance, the current control mode is maintained unchanged;

[0110] In the fault current limiting control mode, by reducing the number of sub-modules put into operation by the high-voltage DC port converter or switching its control mode to the constant DC current control mode, the rapid rise of the DC current is suppressed, and at the same time, a small-capacity DC circuit breaker is used to isolate the faulty line, realizing the non-blocking fault crossing of the DC hub substation;

[0111] The standby high-voltage AC port can be used to transmit power to the local AC grid or to construct an internal AC bus standby power port. When it is used to transmit power to the local AC grid, the control mode is selected according to the strength of the local AC grid. When the short-circuit ratio of the connected AC grid < 3, the grid-forming control mode is adopted. When the short-circuit ratio of the connected AC grid ≥ 3, the constant power control is adopted;

[0112] A three-dimensional DC hub substation operates and controls in the new energy DC aggregation operation control mode. The number of high-voltage DC ports for different DC voltage levels is ≥2, and the high-voltage DC voltage levels can be (but are not limited to) ±200kV, ±400kV, ±500kV, ±800kV, etc. The number of medium-voltage DC ports for different DC voltage levels is ≥1, and the medium-voltage DC voltage levels can be (but are not limited to) ±10kV, ±30kV, ±35kV, ±100kV, etc.; it operates and controls in the multi-drop DC power supply operation control mode. The number of high-voltage DC ports for different DC voltage levels is ≥2, and the high-voltage DC voltage levels can be (but are not limited to) ±200kV, ±400kV, ±500kV, ±800kV, etc. The number of medium-voltage DC ports for different DC voltage levels is ≥1, and the medium-voltage DC voltage levels can be (but are not limited to) ±10kV, ±30kV, ±35kV, ±100kV, etc.

[0113] The external high-voltage DC port, external medium-voltage DC port, and standby high-voltage AC port are all power bi-directional ports, and the operation control method can achieve bi-directional flow control of the power of each port.

[0114] Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

[0115] In the application scenarios of new energy DC aggregation and multi-drop DC power supply, existing AC substations need to go through direct-current to alternating-current conversion to be connected to the AC power grid, which reduces the overall system operation and transmission efficiency of DC power generation - DC power transmission - DC power distribution - DC power consumption. At the same time, a large number of randomly connected AC-DC nodes are generated in the AC substation, increasing the difficulty of power grid regulation and potential safety and stable operation hazards.

[0116] In summary, the present invention specifically proposes an operation control method for a "three-dimensional" DC hub substation. By flexibly and stably controlling the power and voltage of the high-voltage DC port, medium-voltage DC port, and standby AC port, it realizes the interconnection of multi-voltage-level DC lines of high-proportion new energy - power grid - load. Through the embedded fault traveling wave detection module, it realizes fast current limiting of the DC port of the "three-dimensional" DC hub substation and fault-free crossing without blocking. The operation control method of the "three-dimensional" DC hub substation proposed in this application is applicable to the application scenarios of new energy DC aggregation and multi-drop DC power supply.

[0117] Embodiment 2:

[0118] Based on the same inventive concept, the present invention also provides an operation control system for a three-dimensional DC hub substation. The three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including:

[0119] A mode identification module, configured to determine an operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation;

[0120] A mode switching module, configured to determine a control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails under the operation mode corresponding to the operation scenario.

[0121] Optionally, the mode identification module is specifically configured to:

[0122] If the operation scenario of the three-dimensional DC hub substation is new energy collection and transmission, an operation control mode of new energy DC collection is adopted; otherwise, an operation control mode of multi-drop DC power supply is adopted.

[0123] Optionally, the mode switching module includes:

[0124] A first control sub-module, configured to determine a power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid when the operation scenario corresponds to the operation control mode of new energy DC collection;

[0125] A second control sub-module, configured to determine a power control mode of each port of the three-dimensional DC hub substation according to the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station when the operation scenario corresponds to the operation control mode of multi-drop DC power supply.

[0126] Optionally, the first control sub-module includes:

[0127] A first high-voltage port control unit, configured to adopt a constant DC voltage operation control mode for the high-voltage DC port connected to new energy and a v / f operation control mode for the high-voltage DC port connected to the DC power grid when no fault occurs; when a transient traveling wave is detected, fault identification is performed, and mode switching is performed on the high-voltage DC port corresponding to the faulty line;

[0128] A first medium-voltage port control unit, configured to adopt a control mode of constant DC voltage for the medium-voltage DC port connected to new energy;

[0129] A first standby port control unit, configured to determine a power control mode of the standby high-voltage AC port based on the strength of the local AC power grid.

[0130] Optionally, when a transient traveling wave is detected in the first high-voltage port control unit, fault identification is performed, and mode switching is performed on the high-voltage DC port corresponding to the faulty line. The specific implementation process includes:

[0131] When traveling waves on the DC line are detected at the high-voltage DC port connecting to the new energy power station and / or the high-voltage DC port connecting to the DC power grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting to the new energy power station and the high-voltage DC port connecting to the DC power grid;

[0132] Switch the control mode of the high-voltage DC port where the traveling wave generated by the DC short-circuit fault is identified to the fault current limiting control mode.

[0133] Optionally, the first standby port control unit is specifically used for:

[0134] If the short-circuit ratio of the connected AC power grid is less than the set threshold, a grid-forming control mode is adopted; otherwise, a constant power control mode is adopted.

[0135] Optionally, the second control sub-module is used for:

[0136] The second high-voltage port control unit is used for the high-voltage DC port to adopt the v / f operation control mode when no fault occurs; when transient traveling waves are detected, fault identification is performed to determine whether to switch the operation control mode of the high-voltage DC port connecting to the DC power grid;

[0137] The second medium-voltage port control unit is used to determine the control mode of the medium-voltage DC port based on the control mode of the opposite converter station;

[0138] The second standby port control unit is used to determine the power control mode of the standby high-voltage AC port based on the strength of the local AC power grid.

[0139] Optionally, when transient traveling waves are detected in the second high-voltage port control unit, the specific implementation steps for fault identification to determine whether to switch the operation control mode of the high-voltage DC port connecting to the DC power grid include:

[0140] When traveling waves on the DC line are detected at the high-voltage DC port connecting to the DC power grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting to the DC power grid;

[0141] When the identification result is a traveling wave generated by a DC short-circuit fault, switch the control mode of the high-voltage DC port connecting to the DC power grid to the fault current limiting control mode.

[0142] Optionally, the second standby port control unit is specifically used for:

[0143] If the short-circuit ratio of the connected AC power grid is less than the set threshold, a grid-forming control mode is adopted; otherwise, a constant power control mode is adopted.

[0144] Optionally, the second medium-voltage port control unit is specifically used for:

[0145] If the control mode of the opposite converter station is constant DC voltage control, the medium-voltage DC port adopts a constant power operation control mode; otherwise, the medium-voltage DC port adopts a constant DC voltage operation control mode.

[0146] Embodiment 3:

[0147] Based on the same inventive concept, the present invention further provides a computer device, which includes a processor and a memory. The memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a three-dimensional DC hub substation operation control method in the above embodiment.

[0148] Embodiment 4:

[0149] Based on the same inventive concept, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device and is used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and the operating system of the terminal is stored in this storage space. And, one or more instructions suitable for being loaded and executed by the processor are also stored in this storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. One or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the steps of a three-dimensional DC hub substation operation control method in the above embodiment.

[0150] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0151] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0152] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that realizes the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0153] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process, so that the instructions executed on the computer or other programmable devices provide steps for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0154] The above are only embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention pending approval.

Claims

1. A three-dimensional DC hub substation operation control method, characterized in that The three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a spare high-voltage AC port, and an AC busbar, and includes: Based on the operation scenario of the three-dimensional DC hub substation, determine the operation control mode corresponding to the operation scenario; In the operation mode corresponding to the operation scenario, determine the control mode of the DC port of the three-dimensional DC hub substation according to whether a fault occurs in the DC line; The determining the operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation includes: If the operation scenario of the three-dimensional DC hub substation is new energy collection and transmission, the new energy DC collection operation control mode is adopted; otherwise, the multi-drop DC power supply operation control mode is adopted; The determining the control mode of the DC port of the three-dimensional DC hub substation according to whether a fault occurs in the DC line in the operation mode corresponding to the operation scenario includes: When the operation scenario corresponds to the new energy DC collection operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid; When the operation scenario corresponds to the multi-drop DC power supply operation control mode, determine the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station; The determining the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode and the strength of the AC power grid when the operation scenario corresponds to the new energy DC collection operation control mode includes: When no fault occurs, the high-voltage DC port connected to the new energy adopts the constant DC voltage operation control mode, and the high-voltage DC port connected to the DC power grid adopts the v / f operation control mode; When a transient traveling wave is detected, perform fault identification, switch the mode of the high-voltage DC port corresponding to the fault line; adopt the constant DC voltage control mode for the medium-voltage DC port connected to the new energy; determine the power control mode of the spare high-voltage AC port based on the strength of the local AC power grid; The determining the power control mode of each port of the three-dimensional DC hub substation according to the operation control mode, the strength of the AC power grid, and the control mode of the opposite converter station when the operation scenario corresponds to the multi-drop DC power supply operation control mode includes: When no fault occurs, the high-voltage DC port adopts the v / f operation control mode; when a transient traveling wave is detected, perform fault identification to determine whether to switch the operation control mode of the high-voltage DC port connected to the DC power grid; Determine the control mode of the medium-voltage DC port based on the control mode of the opposite converter station; Determine the power control mode of the spare high-voltage AC port based on the strength of the local AC power grid; The high-voltage DC voltage level corresponding to the high-voltage DC port voltage is ±200kV, ±400kV, ±500kV, ±800kV; The medium-voltage DC voltage levels corresponding to the medium-voltage DC port are: ±10kV, ±30kV, ±35kV, ±100kV; When a transient traveling wave is detected, fault identification is performed, and the mode of the high-voltage DC port corresponding to the faulty line is switched, including: When a DC line traveling wave is detected at the high-voltage DC port connecting the new energy power station and / or the high-voltage DC port connecting the DC grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting the new energy power station and the high-voltage DC port connecting the DC grid; The control mode of the high-voltage DC port where the traveling wave generated by the DC short-circuit fault is identified is switched to the fault current limiting control mode; In the fault current limiting control mode, by reducing the number of sub-modules put into operation by the converter of the high-voltage DC port or switching its control mode to the constant DC current control mode, the rapid rise of the DC current is suppressed, and at the same time, a small-capacity DC circuit breaker is used to isolate the faulty line; When a transient traveling wave is detected, fault identification is performed to determine whether to switch the operation control mode of the high-voltage DC port connecting the DC grid, including: When a DC line traveling wave is detected at the high-voltage DC port connecting the DC grid, and the amplitude exceeds a predetermined threshold, fault identification is performed on the high-voltage DC port connecting the DC grid; When the identification result is a traveling wave generated by a DC short-circuit fault, the control mode of the high-voltage DC port connecting the DC grid is switched to the fault current limiting control mode; The operation control of the three-dimensional DC hub substation works in the new energy DC aggregation operation control mode or the multi-drop DC power supply operation control mode. The number of high-voltage DC ports of different DC voltage levels ≥ 2, and the number of medium-voltage DC ports of different DC voltage levels ≥ 1.

2. The method according to claim 1, wherein Based on the control mode of the opposite converter station, determining the control mode of the medium-voltage DC port, including: If the control mode of the opposite converter station is the constant DC voltage control, the medium-voltage DC port adopts the constant power operation control mode, otherwise the medium-voltage DC port adopts the constant DC voltage operation control mode.

3. The method according to claim 1, characterized in that, Based on the strength of the local AC grid, determining the power control mode of the standby high-voltage AC port, including: If the short-circuit ratio of the connected AC grid is less than the set threshold, the grid-forming control mode is adopted, otherwise the constant power control mode is adopted.

4. A system for implementing the operation control method of the three-dimensional DC hub substation according to any one of claims 1 to 3, characterized in that, The three-dimensional DC hub substation includes a high-voltage DC port, a medium-voltage DC port, a standby high-voltage AC port, and an AC bus, including: A mode discrimination module for determining the operation control mode corresponding to the operation scenario based on the operation scenario of the three-dimensional DC hub substation; A mode switching module for determining the control mode of the DC port of the three-dimensional DC hub substation according to whether a DC line fails in the operation mode corresponding to the operation scenario.

5. A computer device, characterized in that, Including: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, an operation control method of a three-dimensional DC hub substation as described in any one of claims 1 to 3 is implemented.

6. A computer-readable storage medium, characterized in that, There is a computer program stored thereon, and when the computer program is executed, an operation control method of a three-dimensional DC hub substation as described in any one of claims 1 to 3 is implemented.

Images