Start control method and device for new energy through hybrid direct current transmission output system

Abstract

The invention relates to the technical field of new energy, and discloses a starting control method and device of a new energy hybrid direct current transmission output system. The method comprises the following steps: after a sending-end flexible direct current converter valve is unlocked, controlling the sending-end flexible direct current converter valve to establish sending-end alternating current bus voltage in a mode of boosting from zero through alternating current voltage amplitude and frequency control so as to start a wind power plant; and meanwhile, active power output of the diesel generator-converter group is controlled, so that the direct-current voltage value of the sending-end flexible direct-current converter valve or the average voltage value of all sub-modules in the sending-end flexible direct-current converter valve is kept at a rated value. And then a sending-end flexible direct current converter valve is controlled to slowly increase the alternating current voltage amplitude of a sending-end bus, a first diode valve and a second diode valve in a sending-end converter station are smoothly conducted, and starting of the new energy mixed direct current transmission sending-out system is completed. According to the method and the device, the equipment cost required in the starting process is reduced, and a simplified and reliable starting control strategy is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a starting control method and device of a new energy hybrid DC transmission delivery system. BACKGROUND

[0002] In a new energy flexible DC delivery system, the sending end flexible DC conversion platform has problems of large volume, large weight and high cost. In order to realize its compactness, lightness and cost reduction, while being compatible with grid-connected and grid-constructing wind turbines, diodes and flexible DC conversion valves are mixed in parallel on the AC side and in series on the DC side, or only diodes and flexible DC conversion valves are mixed in parallel on the AC side. However, this will cause the problem of black start. In the prior art, the black start can be realized by using thyristor converter valves, full-bridge sub-modules or diesel generator-inverter groups. However, the thyristor conversion valve has the risk of commutation failure, the full-bridge sub-module configuration scheme increases the cost of the land flexible DC conversion valve, and the diesel generator-inverter group scheme has problems of complex switching process of grid control function, difficult balance of filter switching timing in black start and easy disturbance to the system. SUMMARY

[0003] Therefore, the present application provides a starting control method and device of a new energy hybrid DC transmission delivery system to solve the problems of complex and unreliable starting control strategy.

[0004] In the first aspect, the present application provides a starting control method of a new energy hybrid DC transmission delivery system, which is used in a new energy hybrid DC transmission delivery system. The system includes a receiving end power grid, a receiving end conversion station, a sending end conversion station and a sending end new energy. The receiving end power grid is connected with the receiving end conversion station. The receiving end conversion station is connected with the sending end conversion station. The sending end conversion station includes a first diode valve, a sending end flexible DC conversion valve, a second diode valve, a diesel generator-inverter group and a sending end AC bus. The first diode valve, the sending end flexible DC conversion valve, the second diode valve and the diesel generator-inverter group are connected with the sending end AC bus respectively. The method includes: After the sending end flexible DC conversion valve in the sending end conversion station is unlocked, the sending end flexible DC conversion valve is controlled to establish the voltage of the sending end AC bus in the form of zero voltage rise through AC voltage amplitude and frequency control, so as to start the wind farm. At the same time, the active power output by the diesel generator-inverter group is controlled, so that the DC voltage value of the sending end flexible DC conversion valve or the average voltage value of all sub-modules in the sending end flexible DC conversion valve is maintained at the corresponding rated value. The first diode valve and the second diode valve in the sending end conversion station are turned on, and the starting of the new energy hybrid DC transmission delivery system is completed.

[0005] The method provided in the embodiment is used for providing energy for the sending-end HVDC valve in the sending-end converter station after the sending-end HVDC valve is unlocked, considering that if the sending-end HVDC valve uses AC voltage amplitude and frequency control, the DC side of the sending-end HVDC valve lacks energy source support, the DC voltage will rapidly drop to cause system collapse. Therefore, the diesel generator-inverter set is used for providing energy for the sending-end HVDC valve. However, the energy required by the sending-end HVDC valve is dynamically changed. Therefore, in the embodiment, the energy required by the sending-end HVDC valve is reflected by the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve. The active power output by the diesel generator-inverter set is controlled to keep the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve at the corresponding rated value, so as to provide energy for the DC side of the sending-end HVDC valve and realize reliable starting of the system.

[0006] In an optional embodiment, the active power output by the diesel generator-inverter set is controlled to keep the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve at the corresponding rated value, including: In the case that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve changes, the sending-end AC bus voltage angular frequency is changed by controlling the sending-end HVDC valve; In the case that the sending-end AC bus voltage angular frequency changes, the active power output by the diesel generator-inverter set is adjusted to keep the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve at the corresponding rated value.

[0007] According to the above-mentioned embodiments, the energy required by the sending-end HVDC valve is reflected by the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve. Specifically, in the case that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve changes, it is determined that the energy required by the sending-end HVDC valve changes, and the sending-end AC bus voltage angular frequency is changed by controlling the sending-end HVDC valve as a signal for adjusting the active power output by the diesel generator-inverter set, so that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve is kept at the corresponding rated value. That is, when the energy required by the sending-end HVDC valve changes, the diesel generator-inverter set can timely adjust the output active power to ensure reliable operation of the sending-end HVDC valve.

[0008] In an optional embodiment, in the case that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve changes, the sending-end HVDC valve is controlled to change the angular frequency of the sending-end AC bus voltage, comprising: According to the DC voltage value of the sending-end HVDC valve at the current moment and the DC voltage reference value, the DC voltage value change amount of the sending-end HVDC valve is determined; According to the DC voltage value change amount of the sending-end HVDC valve, the first angular frequency change amount corresponding to the sending-end AC bus voltage is determined; Or, According to the average voltage value of all sub-modules in the sending-end HVDC valve at the current moment and the average voltage reference value, the average voltage value change amount of all sub-modules in the sending-end HVDC valve is determined; According to the average voltage value change amount of all sub-modules in the sending-end HVDC valve, the second angular frequency change amount corresponding to the sending-end AC bus voltage is determined; According to the first angular frequency change amount or the second angular frequency change amount, the sending-end HVDC valve is controlled to change the angular frequency of the sending-end AC bus voltage.

[0009] In an optional embodiment, according to the DC voltage value change amount of the sending-end HVDC valve, the first angular frequency change amount corresponding to the sending-end AC bus voltage is determined, comprising: The first angular frequency change amount is determined through the DC voltage value change amount of the sending-end HVDC valve and the preset mapping relationship between the DC voltage value change amount and the angular frequency change amount.

[0010] Through the above-mentioned embodiments, by establishing the accurate mapping relationship between the DC voltage value change amount of the sending-end HVDC valve and the angular frequency change amount, the precise closed-loop control of the sending-end HVDC valve voltage is realized. When the DC voltage or the average voltage of the sub-module deviates from the reference value, the corresponding angular frequency change amount of the AC bus voltage can be quickly calculated, so that the sending-end AC bus voltage angular frequency responds, thereby flexibly adjusting the active power output by the diesel generator-inverter group, ensuring the energy supply of the sending-end HVDC valve, and providing a basis for reliable operation of the sending-end HVDC valve.

[0011] In an optional embodiment, in the case that the angular frequency of the sending-end AC bus voltage changes, the active power output by the diesel generator-inverter group is adjusted, so that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve is maintained at the corresponding rated value, comprising: In the case that the angular frequency output by the phase-locked loop in the diesel generator-inverter group changes, it is determined that the angular frequency of the sending-end AC bus voltage changes; determining a target active power according to an angular frequency output by a phase-locked loop at a current moment; controlling the diesel generator-inverter set according to the target active power, so that a DC voltage value of the sending-end HVDC valve or an average voltage value of all sub-modules in the sending-end HVDC valve is maintained at a corresponding rated value.

[0012] Through the above embodiments, the change of the angular frequency of the sending-end AC bus voltage is perceived through the change of the angular frequency output by the phase-locked loop in the diesel generator-inverter set, and the target active power is determined based on the angular frequency output by the phase-locked loop, so as to realize the dynamic correlation between the angular frequency of the sending-end AC bus voltage and the diesel generator-inverter set, and further realize the correlation between the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve and the active power output by the diesel generator-inverter set, i.e., the correlation between the required energy of the sending-end HVDC valve and the active power output by the diesel generator-inverter set, so that the diesel generator-inverter set can timely provide reliable energy supply for the sending-end HVDC valve.

[0013] In an optional embodiment, determining the target active power according to the angular frequency output by the phase-locked loop at the current moment comprises: determining a difference between the angular frequency output by the phase-locked loop at the current moment and a rated angular frequency; determining the target active power according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency.

[0014] In an optional embodiment, determining the target active power according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency comprises: determining the target active power according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency and a preset mapping relationship between the difference of the angular frequency and the active power.

[0015] Through the above embodiments, by establishing the mapping relationship between the difference of the angular frequency output by the phase-locked loop and the active power output by the diesel generator-inverter set, the precise control of the active power output by the diesel generator-inverter set is realized, and the difference between the angular frequency output by the phase-locked loop and the rated angular frequency is taken as the control basis, so as to timely perceive the change of the required energy of the sending-end HVDC valve, quickly determine the active power of the diesel generator-inverter set based on the preset mapping relationship, and make the active power output by the diesel generator-inverter set timely respond to the energy fluctuation required by the sending-end HVDC valve, so as to effectively maintain the stable operation of the sending-end HVDC valve.

[0016] In an optional embodiment, before the sending-end HVDC valve is unlocked, the method further comprises: The diesel generator-inverter set charges the sending-end HVDC converter valve by AC voltage amplitude and frequency control in a zero-voltage-rising manner. After the sending-end HVDC converter valve is charged, the diesel generator-inverter set is controlled to reduce the voltage of the sending-end AC bus to 0.

[0017] In an alternative embodiment, the sending-end converter station further comprises a first rectifier transformer, a sending-end HVDC coupling transformer, a second rectifier transformer, and a filter; the first diode valve is connected to the sending-end AC bus through the first rectifier transformer and a first circuit breaker in sequence; the sending-end HVDC converter valve is connected to the sending-end AC bus through the sending-end HVDC coupling transformer; the second diode valve is connected to the sending-end AC bus through the second rectifier transformer and a second circuit breaker in sequence; and the filter is connected to the sending-end AC bus through a third circuit breaker. After the sending-end HVDC converter valve is charged, the diesel generator-inverter set is controlled to reduce the voltage of the sending-end AC bus to 0, and before the sending-end HVDC converter valve is controlled to establish the voltage of the sending-end AC bus by AC voltage amplitude and frequency control in a zero-voltage-rising manner, the method further comprises: closing the first circuit breaker, the second circuit breaker, and the third circuit breaker; unlocking the sending-end HVDC converter valve.

[0018] By the above embodiment, the sending-end HVDC converter valve is charged by the diesel generator-inverter set in a zero-voltage-rising manner, which can avoid the surge current impact during direct charging, guarantee the safety of the sub-module capacitors and other elements in the HVDC converter valve, and ensure the smooth and controllable charging process. In addition, after the sending-end HVDC converter valve is charged, the diesel generator-inverter set is controlled to reduce the voltage of the sending-end AC bus to 0, which can avoid the impact current when the switch of the equipment connected to the sending-end AC bus is closed, effectively protect the safety of the equipment, and improve the stability during the system starting process.

[0019] In a second aspect, the application provides a starting control device for a new energy hybrid DC transmission system, which is used in a new energy hybrid DC transmission system, and the system comprises a receiving-end power grid, a receiving-end converter station, a sending-end converter station, and a sending-end new energy; the receiving-end power grid is connected to the receiving-end converter station; the receiving-end converter station is connected to the sending-end converter station, and the sending-end converter station comprises a first diode valve, a sending-end HVDC converter valve, a second diode valve, a diesel generator-inverter set, and a sending-end AC bus; the first diode valve, the sending-end HVDC converter valve, the second diode valve, and the diesel generator-inverter set are connected to the sending-end AC bus. The device comprises: The control module is configured to control the sending-end HVDC valve to establish the voltage of the sending-end AC bus in a zero-voltage-rising manner through AC voltage amplitude and frequency control after the sending-end HVDC valve in the sending-end converter station is unlocked, so as to start the wind farm; and control the active power output by the diesel generator-inverter set, so that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve is kept at the corresponding rated value. The conduction module is configured to turn on the first diode valve and the second diode valve in the sending-end converter station, and complete the start of the new energy through the hybrid DC power transmission and delivery system.

[0020] Through the device provided in the embodiment, after the sending-end HVDC valve in the sending-end converter station is unlocked, considering that if the sending-end HVDC valve adopts AC voltage amplitude and frequency control, the DC side lacks energy source support, and the DC voltage will rapidly drop to cause system collapse, therefore, the diesel generator-inverter set is used to provide energy for the sending-end HVDC valve, but the energy required by the sending-end HVDC valve is dynamically changed, therefore, in the embodiment, the energy required by the sending-end HVDC valve is reflected through the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve, the active power output by the diesel generator-inverter set is controlled, so that the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve is kept at the corresponding rated value, so as to provide energy for the DC side of the sending-end HVDC valve, and realize reliable start of the system.

[0021] In a third aspect, the present application provides a computer device, comprising a memory and a processor, the memory and the processor are communicatively connected with each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the start control method of the new energy through the hybrid DC power transmission and delivery system according to the first aspect or any one of the corresponding embodiments thereof.

[0022] In a fourth aspect, the present application provides a computer readable storage medium, which stores computer instructions, and the computer instructions are used to make a computer execute the start control method of the new energy through the hybrid DC power transmission and delivery system according to the first aspect or any one of the corresponding embodiments thereof.

[0023] In a fifth aspect, the present application provides a computer program product, which comprises computer instructions, and the computer instructions are used to make a computer execute the start control method of the new energy through the hybrid DC power transmission and delivery system according to the first aspect or any one of the corresponding embodiments thereof. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0025] Figure 1 is a circuit diagram of a new energy hybrid DC transmission system according to an embodiment of the present application; Figure 2 is a circuit diagram of another new energy hybrid DC transmission system according to an embodiment of the present application; Figure 3 is a flow chart of a start-up control method of a new energy hybrid DC transmission system according to an embodiment of the present application; Figure 4 is a schematic diagram of determining the angular frequency change amount based on the DC voltage value of the sending end HVDC converter valve according to an embodiment of the present application; Figure 5 is a schematic diagram of determining the angular frequency change amount based on the average voltage value of all sub-modules of the sending end HVDC converter valve according to an embodiment of the present application; Figure 6 is a V / F control schematic diagram of controlling the sending end HVDC converter valve to change the angular frequency of the sending end AC bus voltage according to an embodiment of the present application; Figure 7 is a schematic diagram of determining the target active power based on the phase-locked loop output according to an embodiment of the present application; Figure 8 is a schematic diagram of controlling the diesel generator-inverter group based on the target active power according to an embodiment of the present application; Figure 9 is a flow chart of a start-up control method of a new energy hybrid DC transmission system according to an embodiment of the present application; Figure 10 is a structural schematic diagram of a start-up control device of a new energy hybrid DC transmission system according to an embodiment of the present application; Figure 11 is a structural schematic diagram of a computer device according to an embodiment of the present application; DETAILED DESCRIPTION In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0026] First, the application scenario of the embodiments of the present application is exemplarily introduced.

[0027] At present, in the new energy flexible direct current sending out system, the volume and weight of the sending end flexible direct current conversion platform are too large, and the cost is high. In order to realize the compactness and lightness of the sending end conversion platform, and reduce the cost of the sending end conversion valve, while being compatible with the grid-connected type and network-constructed type wind turbine, in the related technology, the diode and the modular multilevel converter (MMC) are connected in series at the direct current side, so as to reduce the volume, weight and cost of the sending end circulating current platform. However, the connection of the MMC and the diode in series at the direct current side needs to overcome a technical difficulty, that is, the black start problem. This is because the unidirectional conduction characteristic of the diode makes it difficult for the hybrid valve to send electricity from the receiving end to the sending end like a pure flexible direct current system to supply the starting power for the conversion platform and the electric field.

[0028] In order to realize the start of the power supply from the receiving end to the sending end, in the first related technology, a line commutated converter (LCC) is used in the land station, and the LCC has the risk of commutation failure, which reduces the power supply reliability. In the second related technology, the land converter station uses a flexible DC converter valve with a large adjustable DC voltage, and a large number of full-bridge sub-modules need to be configured, which significantly increases the cost of the land flexible DC converter valve. In the third related technology, a small-capacity diesel generator on the offshore converter platform is used, and a converter is combined into a diesel generator converter group. The diesel generator converter group uses network construction control to charge the offshore auxiliary MMC and provide start-up power for a small number of wind turbines. After the offshore auxiliary MMC is charged and the small number of wind turbines start to output power, the network construction control function of the diesel generator converter group is transferred to the offshore auxiliary MMC. Although this start-up method significantly reduces the additional cost of black start, it has two problems. The first problem is that the process of transferring the network construction control function of the diesel generator converter group to the offshore auxiliary MMC is complex. Before the network construction function is transferred, the diesel generator converter group uses network construction control and the offshore auxiliary MMC uses network following control. Then the offshore auxiliary MMC switches from network following control to network construction control. At this time, the diesel generator converter group and the offshore auxiliary MMC jointly construct the network, and a special common network construction strategy needs to be used to avoid conflicts between control quantities. After the two jointly stabilize the network, the diesel generator converter group is switched to network following control. The whole process involves online switching of two types of equipment and common network construction, which is extremely complex. The second problem is that there is a large-capacity filter on the offshore AC bus. If the filter is put into operation during the zero-voltage boosting stage of the diesel generator converter group during black start, the diesel generator converter group needs to compensate the filter reactive power, which results in a high apparent power configuration of the converter, far exceeding the capacity of the diesel generator. If the filter is put into operation after the MMC is charged, although the MMC can be used to compensate the filter capacity, the system has established an AC voltage close to the rated voltage at this time. At this time, the input of the filter will inevitably cause the AC bus voltage to drop instantaneously, causing great disturbance to the system, and in serious cases, it may cause overvoltage, overcurrent, and even instability. Therefore, it is necessary to study a start-up control strategy with low cost, simple control strategy and higher reliability.

[0029] Therefore, the embodiments of the present application provide a start-up control method of a new energy hybrid DC transmission system to solve the problems of complex and unreliable start-up control strategy.

[0030] It should be noted that the execution subject of the method for starting control of the new energy hybrid DC power transmission and delivery system provided by the embodiment of the application can be a device for starting control of the new energy hybrid DC power transmission and delivery system, the device for starting control of the new energy hybrid DC power transmission and delivery system can be realized by software, hardware or a combination of software and hardware to become part or all of an electronic device, and the electronic device can be a server or a terminal. The server in the embodiment of the application can be a server or a server cluster composed of multiple servers, and the terminal in the embodiment of the application can be a smart phone, a personal computer, a tablet computer, a wearable device, a smart robot and other smart hardware devices. In the following method embodiment, the execution subject is taken as an example to be described.

[0031] According to the embodiment of the application, a method for starting control of a new energy hybrid DC power transmission and delivery system is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0032] Figure 1 A circuit diagram of a new energy hybrid DC power transmission and delivery system according to an exemplary embodiment. The system comprises: a receiving end power grid 1, a receiving end converter station 2, a sending end converter station 3 and a sending end new energy (sending end new energy station) 4; the receiving end power grid 1 is connected with the receiving end converter station 2; the receiving end converter station 2 is connected with the sending end converter station 3, and the sending end converter station 3 comprises a first diode valve 31, a sending end flexible DC converter valve (Modular Multilevel Converter, MMC) 32, a second diode valve 33, a diesel generator-converter group 34 and a sending end AC bus 35; the first diode valve 31, the sending end flexible DC converter valve 32, the second diode valve 33 and the diesel generator-converter group 34 are connected with the sending end AC bus 35 respectively.

[0033] Specifically, the receiving end power grid 1 refers to a target power grid that receives and absorbs new energy power. The receiving end power grid 1 includes but is not limited to a transformer substation, a power transmission line, a load device and the like.

[0034] The sending end new energy 4 refers to a new energy station on the sending end side, such as an offshore wind farm, a photovoltaic power station and the like, and the application does not make specific limitations on the sending end new energy 4.

[0035] The receiving end converter station 2 is used to convert DC power into AC power and access the receiving end power grid 1. Exemplarily, the receiving end converter station 2 includes but is not limited to an LCC, a flexible DC converter valve and the like.

[0036] The sending-end converter station 3 is a converter device connecting the sending-end new energy 4 and the DC transmission line. Taking offshore wind power as an example, the sending-end converter station 3 is an offshore converter station, which is connected with the sending-end converter station 3 through a DC submarine cable.

[0037] The diesel generator-inverter set 34 is a device in series connection of a diesel generator and an inverter, which is used for voltage / power support in a starting stage.

[0038] In the Figure 1 , the first diode valve 31, the sending-end HVDC converter valve 32 and the second diode valve 33 are connected in series at the DC side. The diesel generator-inverter set 34 comprises a diesel generator (Generator) 341, a machine side converter (MSC) 342 and a grid side converter (GSC) 343. The diesel generator 341 is connected with the sending-end AC bus 35 through the machine side converter 342, the grid side converter 343, the transformer 42 and the fourth circuit breaker 43 in sequence.

[0039] In addition, in the Figure 1 , in the sending-end converter station 3, a first rectifier transformer 36, a sending-end HVDC connection transformer 37, a second rectifier transformer 38 and a filter 39 are further included. The first diode valve 31 is connected with the sending-end AC bus 35 through the first rectifier transformer 36 and the first circuit breaker 40 in sequence; the sending-end HVDC converter valve 32 is connected with the sending-end AC bus 35 through the sending-end HVDC connection transformer 37; the second diode valve 33 is connected with the sending-end AC bus 35 through the second rectifier transformer 38 and the second circuit breaker 41 in sequence; and the filter 39 is connected with the sending-end AC bus 35 through the third circuit breaker 44. Here, the filter 39 is used for filtering harmonic components at the AC side.

[0040] In the receiving-end converter station 2, the receiving-end converter station 2 comprises a receiving-end HVDC converter valve 21, which is connected with the receiving-end power grid 1 through the fifth circuit breaker 22, the receiving-end HVDC connection transformer 23 and the sixth circuit breaker 24 in sequence.

[0041] Of course, in addition to the above Figure 1 , the first diode valve 31, the sending-end HVDC converter valve 32 and the second diode valve 33 are connected in series at the DC side, the starting control method of the new energy through the hybrid DC transmission system provided by the embodiments of the present application is also applicable to a mode in which the diode valve and the sending-end HVDC converter valve are not connected at the DC side, i.e., the first diode valve 31, the sending-end HVDC converter valve 32 and the second diode valve 33 are only connected in parallel at the AC side and are not connected at the DC side.

[0042] Figure 2 is another circuit diagram of a new energy through a hybrid DC transmission system according to an exemplary embodiment. In Figure 2In the embodiment, the connection mode between the two diode valves and the sending-end HVDC converter valve can be in addition to the parallel connection on the AC side and the series connection on the DC side in the embodiment Figure 1 , and can be only parallel connection on the AC side without any connection on the DC side. In addition, the specific structure of the receiving-end power grid, the receiving-end converter station, the sending-end converter station, the sending-end new energy unit, and the like in the embodiment Figure 1 is similar, and will not be described here.

[0043] The starting control method of the new energy through hybrid DC power transmission and delivery system provided by the embodiment is applicable to the case that the sending-end diode valve and the sending-end HVDC converter valve are in parallel connection on the AC side, and does not make specific limitation on the connection mode between the sending-end diode valve and the sending-end HVDC converter valve 32 on the DC side.

[0044] Figure 3 is a flowchart of a starting control method of a new energy through hybrid DC power transmission and delivery system according to the embodiment. The method is used in the new energy through hybrid DC power transmission and delivery system in the embodiment Figure 1 . As shown in the embodiment Figure 3 , the flowchart includes the following steps. S101: After the sending-end HVDC converter valve 32 in the sending-end converter station 3 is unlocked, the sending-end HVDC converter valve 32 is controlled to establish the sending-end AC bus voltage in the form of zero step-up voltage through AC voltage amplitude and frequency control (V / F control) to start the wind farm; at the same time, the active power output by the diesel generator-converter group is controlled so that the DC voltage value of the sending-end HVDC converter valve 32, or the average voltage value of all sub-modules in the sending-end HVDC converter valve 32, is maintained at the corresponding rated value.

[0045] Specifically, the AC voltage amplitude and frequency control refers to the precise control of the sending-end AC bus voltage by adjusting the AC voltage size and frequency output by the converter valve. The zero step-up voltage refers to gradually increasing the AC voltage from 0 to the rated value to avoid the impact current.

[0046] Starting the wind farm refers to the conversion of at least part of the wind turbine in the wind farm from the shutdown state to the power generation state.

[0047] The DC voltage value of the sending-end HVDC converter valve 32 refers to the voltage across the DC side of the sending-end HVDC converter valve 32, reflecting the power balance state of the converter valve. The average voltage value of all sub-modules in the sending-end HVDC converter valve 32 refers to the average value of the capacitor voltage of all sub-modules in the converter valve, which is used to measure the voltage balance of the sub-modules. The sub-modules in the sending-end HVDC converter valve 32 can be full-bridge sub-modules or half-bridge sub-modules.

[0048] In a possible implementation, in the S101, the diesel generator-inverter group adopts a constant active power and constant reactive power control (P / Q control) to provide energy for transformer no-load loss, wind farm start, etc.

[0049] S102: Turn on the first diode valve 31 and the second diode valve 33 in the sending-end converter station 3, and complete the start of the new energy through the hybrid DC power transmission to the system.

[0050] In a possible implementation, in the S102, the control sending-end flexible AC transmission system (FACTS) valve 32 raises the voltage of the sending-end AC bus 35 until the second diode valve 33 and the second diode valve 33 are turned on, and the diesel generator-inverter group 34 exits the operation.

[0051] Through the method provided in the embodiment, after the sending-end FACTS valve 32 in the sending-end converter station 3 is unlocked, considering that if the sending-end FACTS valve 32 adopts AC voltage amplitude and frequency control, the DC side lacks energy source support, the DC voltage will rapidly drop to cause system collapse, therefore, the diesel generator-inverter group needs to provide energy for the sending-end FACTS valve 32, but the energy required by the sending-end FACTS valve 32 is dynamically changed, thus, in the embodiment, the energy required by the sending-end FACTS valve 32 is reflected through the DC voltage value of the sending-end FACTS valve 32 or the average voltage value of all sub-modules in the sending-end FACTS valve 32, the active power output by the diesel generator-inverter group is controlled to make the DC voltage value of the sending-end FACTS valve 32 or the average voltage value of all sub-modules in the sending-end FACTS valve 32 keep at the corresponding rated value, so as to provide energy for the DC side of the sending-end FACTS valve 32 and realize reliable start of the system.

[0052] In some embodiments, in the S101, the active power output by the diesel generator-inverter group is controlled in such a way that the DC voltage value of the sending-end FACTS valve 32 or the average voltage value of all sub-modules in the sending-end FACTS valve 32 keeps at the corresponding rated value: a1: In the case that the DC voltage value of the sending-end FACTS valve 32 or the average voltage value of all sub-modules in the sending-end FACTS valve 32 changes, the sending-end FACTS valve 32 is controlled to change the angular frequency of the voltage of the sending-end AC bus.

[0053] In a possible implementation, in the a1, in the case that the DC voltage value of the sending-end FACTS valve 32 changes, the sending-end FACTS valve 32 is controlled to change the angular frequency of the voltage of the sending-end AC bus.

[0054] In another possible implementation, in the a1 above, in the case that the average voltage value of all sub-modules in the sending-end HVDC valve 32 changes, the sending-end HVDC valve 32 is controlled to change the angular frequency of the sending-end AC bus voltage.

[0055] a2: In the case that the angular frequency of the sending-end AC bus voltage changes, the active power output by the diesel generator-inverter set is adjusted, so that the DC voltage value of the sending-end HVDC valve 32, or the average voltage value of all sub-modules in the sending-end HVDC valve 32, is kept at the corresponding rated value.

[0056] In the embodiments of the present application, the DC voltage value of the sending-end HVDC valve 32, or the average voltage value of all sub-modules in the sending-end HVDC valve 32, reflects the change in the energy required by the sending-end HVDC valve 32, specifically, in the case that the DC voltage value of the sending-end HVDC valve 32, or the average voltage value of all sub-modules in the sending-end HVDC valve 32, changes, it is determined that the energy required by the sending-end HVDC valve 32 changes, and the sending-end HVDC valve 32 is controlled to change the angular frequency of the sending-end AC bus voltage as a signal to adjust the active power output by the diesel generator-inverter set, so that the DC voltage value of the sending-end HVDC valve 32, or the average voltage value of all sub-modules in the sending-end HVDC valve 32, is kept at the corresponding rated value, that is, when the energy required by the sending-end HVDC valve 32 changes, the diesel generator-inverter set can timely adjust the output active power, ensuring reliable operation of the sending-end HVDC valve 32.

[0057] In a possible implementation, in the a1 above, the sending-end HVDC valve 32 is controlled to change the angular frequency of the sending-end AC bus voltage by the following b1-b2: b1: According to the DC voltage value of the sending-end HVDC valve 32 at the current time and the DC voltage reference value, the change amount of the DC voltage value of the sending-end HVDC valve 32 is determined, or, according to the average voltage value of all sub-modules in the sending-end HVDC valve 32 at the current time and the average voltage reference value, the change amount of the average voltage value of all sub-modules in the sending-end HVDC valve 32 is determined.

[0058] For example, the DC voltage value of the sending-end HVDC valve 32 and the DC voltage reference value are subtracted to obtain the change amount of the DC voltage value of the sending-end HVDC valve 32.

[0059] For example, the average voltage value of all sub-modules in the sending-end HVDC valve 32 at the current time and the average voltage reference value are subtracted to obtain the change amount of the average voltage value of the sending-end HVDC valve 32.

[0060] b2: determining a first angular frequency variation corresponding to the sending end AC bus voltage according to the sending end HVDC valve 32 DC voltage value variation, or determining a second angular frequency variation corresponding to the sending end AC bus voltage according to the sending end HVDC valve 32 all sub-modules average voltage value variation.

[0061] Optionally, the first angular frequency variation is determined through the sending end HVDC valve 32 DC voltage value variation and the preset mapping relationship between the DC voltage value variation and the angular frequency variation.

[0062] Optionally, the first angular frequency variation is determined through the sending end HVDC valve 32 DC voltage value variation and the preset mapping relationship between the DC voltage value variation and the angular frequency variation.

[0063] Optionally, the second angular frequency variation is determined through the sending end HVDC valve 32 all sub-modules average voltage value variation and the preset mapping relationship between the average voltage value variation and the angular frequency variation.

[0064] b3: controlling the sending end HVDC valve 32 to change the angular frequency of the sending end AC bus voltage according to the first angular frequency variation or the second angular frequency variation.

[0065] Figure 4 The schematic diagram for determining the angular frequency variation based on the sending end HVDC valve DC voltage value is shown in FIG. 1. Figure 4 In FIG. 1, U dcref The sending end HVDC valve DC voltage reference value is Vref. U dc The sending end HVDC valve DC voltage value is V. sT um The low-pass filter is LPF, and the proportional integral controller is PI. ω The sending end AC bus voltage angular frequency variation is Δω. Figure 4 As shown in FIG. 2, the sending end HVDC valve 32 further determines the park transformation angle of the fundamental frequency to be controlled based on the sending end AC bus voltage angular frequency variation. Wherein, ω N The rated angular frequency is ω0. ω PCC The sending end HVDC valve 32 needs to control the sending end AC bus voltage angular frequency value is ω. s The integral module is I. θ g The sending end HVDC valve 32 controlled transformer grid side fundamental frequency electrical quantity park transformation angle is θ. θ T The sending end HVDC coupling transformer 37 valve side winding and grid side winding phase angle difference is φ.θ v Park transformation angle of transformer valve side fundamental frequency electrical quantity controlled by sending end HVDC valve 32.

[0066] Figure 5 Schematic diagram for determining angular frequency variation based on average voltage value of all sub-modules of sending end HVDC valve. U SMref Average voltage reference value of all sub-modules of sending end HVDC valve, U SM_av Average voltage value of all sub-modules, PI is proportional integral controller, Δ ω Angular frequency variation of sending end AC bus voltage, ω N Rated angular frequency, ω PCC Angular frequency value of sending end AC bus voltage required by sending end HVDC valve 32, 1 / s Integral module, θ g Park transformation angle of transformer grid side fundamental frequency electrical quantity controlled by sending end HVDC valve 32, θ T Phase angle difference between valve side winding and grid side winding of sending end HVDC coupling transformer 37; θ v Park transformation angle of transformer valve side fundamental frequency electrical quantity controlled by sending end HVDC valve 32.

[0067] In Figure 6 , the transformation angle Figure 4 or Figure 5 determined based on θ v , the sending end HVDC valve is controlled to change the angular frequency of the sending end AC bus voltage. Wherein, V dref , V qref are respectively the d, q axis component reference values of the sending end AC bus voltage; V gd , V gq are respectively the d, q axis component measured values of the sending end AC bus voltage; I dref , I qref are respectively the d, q axis component reference values of the AC side current of the sending end HVDC valve 32; e cd , e cq are respectively I dref , Iqref d, q axis components of the output AC voltage reference value of the grid-side converter output after inputting the control instruction into the current inner loop control link; e aref 、 e bref 、 e cref are respectively the three-phase AC voltage reference value of the sending-end MMC output; e cira 、 e cirb 、 e circ is the three-phase two-frequency AC voltage reference value of the sending-end MMC output through the circulating current suppression control; P 1 is park transformation; N ap 、 N an 、 N bp 、 N bn 、 N cp 、 N cn are respectively the sub-module number reference value required to be put into the three-phase 6-bridge arm of the sending-end flexible DC converter valve 32 output through nearest level modulation (NLM); PI is a proportional integral controller.

[0068] In the embodiment of the present application, by establishing the mapping relationship between the voltage value change amount and the angular frequency change amount of the sending-end flexible DC converter valve 32, accurate closed-loop control of the voltage of the sending-end flexible DC converter valve 32 is realized. When the DC voltage or the average voltage of the sub-modules deviates from the reference value, the corresponding angular frequency change amount of the AC bus voltage can be quickly calculated, so that the sending-end AC bus voltage angular frequency responds, thereby flexibly adjusting the active power output by the diesel generator-converter group, ensuring the energy supply of the sending-end flexible DC converter valve, and providing a basis for reliable operation of the sending-end flexible DC converter valve.

[0069] In a possible implementation, in the above a2, the active power output by the diesel generator-converter group is adjusted through c1-c3 as follows: c1: In the case where the phase-locked loop output angular frequency in the diesel generator-converter group 34 changes, it is determined that the angular frequency of the sending-end AC bus voltage changes.

[0070] c2: According to the phase-locked loop output angular frequency at the current time, the target active power is determined.

[0071] Optionally, in the above c2, the target active power is determined through the following contents: Firstly, a difference between the angular frequency output by the phase-locked loop and the rated angular frequency is determined.

[0072] Then, the target active power is determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency.

[0073] For example, the target active power can be determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency, and a preset mapping relationship between the angular frequency difference and the active power.

[0074] For example, the target active power can be determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency, and a preset mapping relationship between the angular frequency difference and the active power.

[0075] Figure 7 is a schematic diagram for determining the target active power based on the angular frequency output by the phase-locked loop. ω N is the rated angular frequency, ω PLL is the angular frequency output by the phase-locked loop, 1 / (1+ sT um is a low-pass filter, and PI is a proportional-integral controller, P ref is the target active power. In Figure 7 , the target active power of the diesel generator-inverter set is determined by the difference between the angular frequency output by the phase-locked loop and the rated angular frequency, and a preset mapping relationship between the angular frequency difference and the active power in the proportional-integral controller.

[0076] In this way, by establishing the mapping relationship between the angular frequency difference output by the phase-locked loop and the active power output by the diesel generator-inverter set, precise control of the active power output by the diesel generator-inverter set is achieved. The difference between the angular frequency output by the phase-locked loop and the rated angular frequency is used as a control basis, which can timely perceive the energy change required by the sending-end HVDC valve, quickly determine the active power of the diesel generator-inverter set based on the preset mapping relationship, and make the active power output by the diesel generator-inverter set timely respond to the energy fluctuation required by the sending-end HVDC valve, thereby effectively maintaining the stable operation of the sending-end HVDC valve.

[0077] c3: According to the target active power, the diesel generator-inverter set 34 is controlled so that the DC voltage value of the sending-end HVDC valve 32, or the average voltage value of all sub-modules in the sending-end HVDC valve 32, is maintained at the corresponding rated value.

[0078] Figure 8 is a schematic diagram for controlling the diesel generator-inverter set based on the target active power. In Figure 8 , the diesel generator-inverter set is controlled based on the target active power determined by the difference between the angular frequency output by the phase-locked loop and the rated angular frequency, and a preset mapping relationship between the angular frequency difference and the active power in the proportional-integral controller.Figure 7 The diesel generator-inverter set is controlled according to the target active power determined by the method. Wherein, P ref , Q ref are respectively the reference values of the active and reactive power output by the grid-side converter; P , Q are respectively the measured values of the active and reactive power output by the grid-side converter; I dref , I qref are respectively the reference instructions of the d-axis and q-axis components of the alternating current on the grid-side converter; e cd , e cq are respectively I dref , I qref are respectively the d-axis and q-axis components of the grid-side converter output alternating voltage reference values output after the current inner loop control link as control instructions; e aref , e bref , e cref are respectively the three-phase alternating voltage reference values output by the grid-side converter; G 1、 G 2、 G 3、 G 4、 G 5、 G 6 are respectively the trigger pulse signals of the three-phase 6-bridge arms of the grid-side converter output by pulse width modulation (PWM); P 1 is park transformation; 1 / (1+ sT um ) is a filter; U gq is the measured value of the q-axis component of the alternating current on the grid-side converter grid connection point; PI is a proportional integral controller; ω N is the rated angular frequency; ω PLL is the angular frequency output by the phase-locked loop; 1 / s is an integral module; θ is the park transformation angle of the grid-side converter base frequency electrical quantity of the diesel generator-inverter set.

[0079] In the embodiment of the present application, the change in the angular frequency of the voltage of the sending end AC bus is perceived through the change in the angular frequency output by the phase-locked loop in the diesel generator-inverter set, and the target active power is determined based on the angular frequency output by the phase-locked loop, thereby realizing the dynamic correlation between the angular frequency of the voltage of the sending end AC bus and the diesel generator-inverter set, and further realizing the correlation between the DC voltage value of the sending end HVDC valve or the average voltage value of all sub-modules in the sending end HVDC valve and the active power output by the diesel generator-inverter set, that is, the correlation between the required energy of the sending end HVDC valve and the active power output by the diesel generator-inverter set, so that the diesel generator-inverter set can provide reliable energy supply for the sending end HVDC valve in time.

[0080] In some embodiments, before the sending end HVDC valve 32 is unlocked, the starting control method provided by the embodiment of the present application further includes the following content: First, the diesel generator-inverter set 34 is controlled to charge the sending end HVDC valve 32 in a zero-rise voltage boosting manner through AC voltage amplitude and frequency control.

[0081] Specifically, the diesel generator-inverter set 34 adopts V / F control zero-rise voltage boosting to charge the sub-module capacitors in the sending end HVDC valve 32.

[0082] Then, after the charging of the sending end HVDC valve 32 is completed, the diesel generator-inverter set 34 is controlled to reduce the voltage of the sending end AC bus to 0.

[0083] In some embodiments, after the sending end HVDC valve 32 is charged to 0, before the sending end HVDC valve 32 is controlled to establish the voltage of the sending end AC bus in a zero-rise voltage boosting manner through AC voltage amplitude and frequency control, the method provided by the embodiment of the present application further includes the following content: First, the first circuit breaker 40, the second circuit breaker 41 and the third circuit breaker 44 are closed.

[0084] Then, the sending end HVDC valve 32 is unlocked.

[0085] Through the above-mentioned embodiments, the diesel generator-inverter set charges the HVDC valve in a zero-rise voltage boosting manner, which can avoid the surge current impact during direct charging, guarantee the safety of the sub-module capacitors and other elements in the HVDC valve, and ensure the smooth and controllable charging process. In addition, after the sending end HVDC valve is charged, the diesel generator-inverter set is controlled to reduce the voltage of the sending end AC bus to 0, which can avoid the impact current generated when the switches of the devices connected to the sending end AC bus are closed, effectively protect the safety of the devices, and improve the stability during the system starting process.

[0086] Figure 9A flow chart of a starting control method of a new energy hybrid DC transmission system. As shown in Figure 9 the method comprises the following contents: S901: control the diesel generator-inverter set 34 to charge the sending-end HVDC converter valve 32 by AC voltage amplitude and frequency control in a zero-voltage-rising manner.

[0087] S902: after the charging of the sending-end HVDC converter valve 32 is completed, control the diesel generator-inverter set 34 to reduce the sending-end AC bus voltage to 0.

[0088] S903: close the first breaker 40, the second breaker 41 and the third breaker 44, and unlock the sending-end HVDC converter valve 32 in the sending-end converter station.

[0089] S904: the sending-end HVDC converter valve 32 maps the change amount information of the sending-end HVDC converter valve 32 DC voltage value or the average voltage value of all sub-modules in the sending-end HVDC converter valve 32 by controlling the sending-end AC bus voltage angle frequency change, and further, the grid-side converter in the diesel generator-inverter set 34 adjusts the active power output based on the angle frequency change amount output by the phase-locked loop until the sending-end HVDC converter valve 32 DC voltage value or the average voltage value of all sub-modules in the sending-end HVDC converter valve 32 recovers and remains at the rated value.

[0090] S905: turn on the first diode valve 31 and the second diode valve 33 in the sending-end converter station, and complete the starting of the new energy hybrid DC transmission system.

[0091] In the embodiments of the present application, a dynamic coordination control strategy between the sending-end HVDC converter valve and the diesel generator-inverter set is proposed, which significantly reduces the cost of additional equipment required for black start, the control strategy is simple and easy to implement, and has high reliability and stability during the black start process.

[0092] The above mainly introduces the scheme provided by the embodiments of the present application from the perspective of the method.

[0093] In the embodiments of the present application, a starting control device of a new energy hybrid DC transmission system is also provided, which is used to implement the above embodiments and preferred embodiments, and details are not repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware is also possible and is conceived.

[0094] The application provides a starting control device of a new energy hybrid DC transmission system, which is used for the new energy hybrid DC transmission system, and the system comprises a receiving end power grid, a receiving end converter station, a sending end converter station and a sending end new energy source; the receiving end power grid is connected with the receiving end converter station; the receiving end converter station is connected with the sending end converter station, and the sending end converter station comprises a first diode valve, a sending end flexible DC converter valve, a second diode valve, a diesel generator-inverter group and a sending end AC bus; the first diode valve, the sending end flexible DC converter valve, the second diode valve and the diesel generator-inverter group are connected with the sending end AC bus; as shown in the figure, Figure 10 The device comprises: A control module 1001 is configured to, after the sending end flexible DC converter valve in the sending end converter station is unlocked, control the sending end flexible DC converter valve to establish the sending end AC bus voltage in a zero-voltage-rising manner through AC voltage amplitude and frequency control, so as to start the wind farm; meanwhile, control the active power output by the diesel generator-inverter group, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value. A conduction module 1002 is configured to conduct the first diode valve and the second diode valve in the sending end converter station, and complete the starting of the new energy hybrid DC transmission system.

[0095] Through the device provided in the embodiment, after the sending end flexible DC converter valve in the sending end converter station is unlocked, considering that if the sending end flexible DC converter valve adopts AC voltage amplitude and frequency control, the DC side lacks energy source support, the DC voltage will rapidly drop to cause system collapse, therefore, the diesel generator-inverter group is used to provide energy for the sending end flexible DC converter valve, but the energy required by the sending end flexible DC converter valve is dynamically changed, therefore, in the embodiment, the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is used to reflect the energy change required by the sending end flexible DC converter valve, the active power output by the diesel generator-inverter group is controlled, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value, thereby energy is provided for the DC side of the sending end flexible DC converter valve, and reliable starting of the system is realized.

[0096] In some optional embodiments, the control module 1001 is specifically configured to, in the case that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve changes, control the sending end flexible DC converter valve to change the angular frequency of the sending end AC bus voltage. In the case that the angular frequency of the sending end AC bus voltage changes, the active power output by the diesel generator-inverter group is adjusted, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value.

[0097] In some optional embodiments, the control module 1001 is specifically configured to determine a change amount of the DC voltage value of the sending-end HVDC valve according to the DC voltage value of the sending-end HVDC valve at the current moment and the DC voltage reference value; determine a change amount of the first angular frequency corresponding to the sending-end AC bus voltage according to the change amount of the DC voltage value of the sending-end HVDC valve; Alternatively, determine a change amount of the average voltage value of all sub-modules in the sending-end HVDC valve according to the average voltage value of all sub-modules in the sending-end HVDC valve at the current moment and the average voltage reference value; determine a change amount of the second angular frequency corresponding to the sending-end AC bus voltage according to the change amount of the average voltage value of all sub-modules in the sending-end HVDC valve; control the sending-end HVDC valve to change the angular frequency of the sending-end AC bus voltage according to the first angular frequency change amount or the second angular frequency change amount.

[0098] In some optional embodiments, the control module 1001 is specifically configured to determine the first angular frequency change amount by the change amount of the DC voltage value of the sending-end HVDC valve and a preset mapping relationship between the change amount of the DC voltage value and the angular frequency change amount.

[0099] In some optional embodiments, the control module 1001 is specifically configured to determine that the angular frequency of the sending-end AC bus voltage changes in the case that the angular frequency output by the phase-locked loop in the diesel generator-inverter group changes; determine the target active power according to the angular frequency output by the phase-locked loop at the current moment; control the diesel generator-inverter group to keep the DC voltage value of the sending-end HVDC valve or the average voltage value of all sub-modules in the sending-end HVDC valve at a corresponding rated value according to the target active power.

[0100] In some optional embodiments, the control module 1001 is specifically configured to determine a difference between the angular frequency output by the phase-locked loop at the current moment and the rated angular frequency; determine the target active power according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency.

[0101] In some optional embodiments, the control module 1001 is specifically configured to determine the target active power according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency and a preset mapping relationship between the angular frequency difference and the active power.

[0102] In some optional embodiments, the control module 1001 is further configured to control the diesel generator-inverter set to charge the sending-end HVDC valve in a manner of boosting from zero through AC voltage amplitude and frequency control before the sending-end HVDC valve is unlocked. After the sending-end HVDC valve is charged, the control module 1001 is further configured to control the diesel generator-inverter set to reduce the voltage of the sending-end AC bus to 0.

[0103] In some optional embodiments, the sending-end converter station further comprises a first rectifier transformer, a sending-end HVDC coupling transformer, a second rectifier transformer, and a filter; the first diode valve is connected to the sending-end AC bus through the first rectifier transformer and a first circuit breaker in sequence; the sending-end HVDC valve is connected to the sending-end AC bus through the sending-end HVDC coupling transformer; the second diode valve is connected to the sending-end AC bus through the second rectifier transformer and a second circuit breaker in sequence; the filter is connected to the sending-end AC bus through a third circuit breaker; and the control module 1001 is further configured to, after the sending-end HVDC valve is charged and the voltage of the sending-end AC bus is reduced to 0, control the first circuit breaker, the second circuit breaker, and the third circuit breaker to be closed before the sending-end HVDC valve establishes the voltage of the sending-end AC bus in a manner of boosting from zero through AC voltage amplitude and frequency control, and then unlock the sending-end HVDC valve.

[0104] Further function descriptions of the above-mentioned modules and units are the same as those of the corresponding embodiments, and thus are not described herein again.

[0105] The start control device of the new energy hybrid DC transmission system in the embodiment is presented in the form of functional units, where the units refer to ASIC (Application Specific Integrated Circuit, special integrated circuit) circuits, processors and memories executing one or more software or fixed programs, and / or other devices capable of providing the above functions.

[0106] The embodiment of the present application further provides a computer device having the start control device of the new energy hybrid DC transmission system shown in the above Figure 10 .

[0107] Please refer to Figure 11 , Figure 11 is a structural schematic diagram of a computer device provided by an optional embodiment of the present application, as shown in Figure 11As shown, the computer device includes one or more processors 10, memory 20, and interfaces 30 for external devices such as a keyboard and a mouse and peripheral devices such as disk devices or other storage devices. One or more busses 10 can be used to implement the interface between the various circuits and components of the computer device. It will be appreciated that the bus 10 can be implemented using any one or more of a variety of bus structures, such as a Peripheral Component Interconnect (PCI) bus, a Bluetooth bus, an Industry Standard Architecture (ISA) bus, an Enhanced ISA bus, an Accelerated Graphics Port (AGP) bus, a Video Electronics Standards Association (VESA) local bus, a Micro Channel Architecture (MCA) bus, a Universal Serial Bus (USB), and the like. Figure 11 The processor 10 is used in the embodiments as an example.

[0108] The processor 10 can be a central processing unit, a network processor, or a combination thereof. The processor 10 can further include a hardware chip. The hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device can be a complex programmable logic device, a field programmable logic device, a general array logic, or any combination thereof.

[0109] The memory 20 stores instructions that can be executed by the at least one processor 10, so that the at least one processor 10 can perform the method shown in the above embodiments.

[0110] The memory 20 can include a program region and a data region. The program region can store an operating system and application programs required by at least one function. The data region can store data created by the use of the computer device, and the like. In addition, the memory 20 can include a high-speed random access memory, and can further include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some alternative embodiments, the memory 20 can optionally include a memory that is remotely arranged with respect to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0111] The memory 20 can include a volatile memory, such as a random access memory, and can also include a non-volatile memory, such as a flash memory, a hard disk, or a solid state disk. The memory 20 can further include a combination of the above-mentioned kinds of memories.

[0112] The computer device further includes a communication interface 30 for communication with other devices or communication networks.

[0113] The embodiments of the present application further provide a computer readable storage medium, and the method according to the embodiments of the present application can be implemented in hardware, firmware, or recorded in a storage medium, or stored in a remote storage medium or a non-transitory machine readable storage medium and downloaded to a local storage medium through network, so that the method described herein can be processed by such software on a storage medium using a general purpose computer, a special purpose processor, or programmable or special hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid state disk, etc. Further, the storage medium can also include a combination of the above-mentioned memories. It can be understood that the computer, the processor, the microprocessor controller, or the programmable hardware includes a storage component that can store or receive software or computer code, when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0114] Part of the present application can be applied as a computer program product, for example, computer program instructions, when executed by a computer, through the operation of the computer, the method and / or technical solutions according to the present application can be called or provided. Those skilled in the art should understand that the form of computer program instructions in a computer readable medium includes but is not limited to source files, executable files, installation package files, etc. Correspondingly, the way of executing computer program instructions by computer includes but is not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer readable medium can be any available computer readable storage medium or communication medium accessible to the computer.

[0115] Although the embodiments of the present application are described in conjunction with the accompanying drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A starting control method of a new energy hybrid DC power transmission and delivery system, characterized by, The application relates to a new energy hybrid DC transmission delivery system, which comprises a receiving end power grid, a receiving end converter station, a sending end converter station and a sending end new energy source; the receiving end power grid is connected with the receiving end converter station; the receiving end converter station is connected with the sending end converter station, and the sending end converter station comprises a first diode valve, a sending end flexible DC converter valve, a second diode valve, a diesel generator-inverter set and a sending end AC bus; the first diode valve, the sending end flexible DC converter valve, the second diode valve and the diesel generator-inverter set are respectively connected with the sending end AC bus. The method comprises the following steps: After the sending end flexible DC converter valve in the sending end converter station is unlocked, the sending end flexible DC converter valve is controlled to establish the sending end AC bus voltage in the form of zero voltage rise through AC voltage amplitude and frequency control, so as to start the wind power plant; meanwhile, the active power output by the diesel generator-inverter set is controlled, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value; The first diode valve and the second diode valve in the sending end converter station are turned on, and the starting of the new energy hybrid DC transmission delivery system is completed.

2. The method of claim 1, wherein, The control of the active power output by the diesel generator-inverter set, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value, comprises the following steps: In the case that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve changes, the sending end flexible DC converter valve is controlled to change the angular frequency of the sending end AC bus voltage; In the case that the angular frequency of the sending end AC bus voltage changes, the active power output by the diesel generator-inverter set is adjusted, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value.

3. The method of claim 2, wherein, The control of the sending end flexible DC converter valve to change the angular frequency of the sending end AC bus voltage in the case that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve changes, comprises the following steps: According to the DC voltage value of the sending end flexible DC converter valve at the current moment and a DC voltage reference value, the DC voltage value change amount of the sending end flexible DC converter valve is determined; According to the DC voltage value change amount of the sending end flexible DC converter valve, the first angular frequency change amount corresponding to the sending end AC bus voltage is determined; Or, According to the average voltage value of all sub-modules in the sending end flexible DC converter valve at the current moment and an average voltage reference value, the average voltage value change amount of all sub-modules in the sending end flexible DC converter valve is determined; According to the average voltage value change amount of all sub-modules in the sending end flexible DC converter valve, the second angular frequency change amount corresponding to the sending end AC bus voltage is determined; According to the first angular frequency change amount or the second angular frequency change amount, the sending end flexible DC converter valve is controlled to change the angular frequency of the sending end AC bus voltage.

4. The method of claim 3, wherein, The first angular frequency variation of the sending end AC bus voltage is determined according to the DC voltage value variation of the sending end HVDC valve, and the method comprises the following steps: The first angular frequency variation is determined according to the DC voltage value variation of the sending end HVDC valve and a preset mapping relationship between the DC voltage value variation and the angular frequency variation.

5. The method of claim 2, wherein, The active power output by the diesel generator-inverter group is adjusted to keep the DC voltage value of the sending end HVDC valve or the average voltage value of all sub-modules in the sending end HVDC valve at a corresponding rated value when the angular frequency of the sending end AC bus voltage changes, and the method comprises the following steps: The angular frequency of the sending end AC bus voltage is determined to change when the angular frequency output by the phase-locked loop in the diesel generator-inverter group changes; The target active power is determined according to the angular frequency output by the phase-locked loop at the current time; The diesel generator-inverter group is controlled according to the target active power to keep the DC voltage value of the sending end HVDC valve or the average voltage value of all sub-modules in the sending end HVDC valve at a corresponding rated value.

6. The method of claim 5, wherein, The target active power is determined according to the angular frequency output by the phase-locked loop at the current time, and the method comprises the following steps: The difference between the angular frequency output by the phase-locked loop at the current time and the rated angular frequency is determined; The target active power is determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency.

7. The method of claim 6, wherein, The target active power is determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency, and the method comprises the following steps: The target active power is determined according to the difference between the angular frequency output by the phase-locked loop and the rated angular frequency and a preset mapping relationship between the angular frequency difference and the active power.

8. The method according to any one of claims 1-7, characterized in that, Before the sending end HVDC valve is unlocked, the method further comprises the following steps: The diesel generator-inverter group is controlled to charge the sending end HVDC valve in a zero-voltage-rising manner through AC voltage amplitude and frequency control; After the sending end HVDC valve is fully charged, the sending end AC bus voltage is controlled to be reduced to 0 by the diesel generator-inverter group.

9. The method of claim 8, wherein, The sending end converter station further comprises a first rectifier transformer, a sending end HVDC coupling transformer, a second rectifier transformer and a filter; the first diode valve is connected to the sending end AC bus through the first rectifier transformer and a first circuit breaker in sequence; the sending end HVDC valve is connected to the sending end AC bus through the sending end HVDC coupling transformer; the second diode valve is connected to the sending end AC bus through a second rectifier transformer and a second circuit breaker in sequence; and the filter is connected to the sending end AC bus through a third circuit breaker; After the sending end AC bus voltage is reduced to 0 by the diesel generator-inverter group after the sending end HVDC valve is fully charged, and before the sending end AC bus voltage is established by the sending end HVDC valve through AC voltage amplitude and frequency control in a zero-voltage-rising manner, the method further comprises the following steps: The first circuit breaker, the second circuit breaker and the third circuit breaker are closed; The sending end HVDC valve is unlocked.

10. A start-up control device for a new energy transmission system via hybrid DC power transmission, characterized in that, The application relates to a new energy hybrid DC transmission delivery system, which comprises a receiving end power grid, a receiving end converter station, a sending end converter station and a sending end new energy source; the receiving end power grid is connected with the receiving end converter station; the receiving end converter station is connected with the sending end converter station, and the sending end converter station comprises a first diode valve, a sending end flexible DC converter valve, a second diode valve, a diesel generator-inverter group and a sending end AC bus; the first diode valve, the sending end flexible DC converter valve, the second diode valve and the diesel generator-inverter group are respectively connected with the sending end AC bus. The device comprises: a control module, which is used for controlling the sending end flexible DC converter valve in the sending end converter station to establish the sending end AC bus voltage in the form of zero voltage rise through AC voltage amplitude and frequency control after the sending end flexible DC converter valve is unlocked, so as to start the wind power plant; meanwhile, the active power output by the diesel generator-inverter group is controlled, so that the DC voltage value of the sending end flexible DC converter valve or the average voltage value of all sub-modules in the sending end flexible DC converter valve is kept at the corresponding rated value; a conduction module, which is used for conducting the first diode valve and the second diode valve in the sending end converter station, and completing the starting of the new energy hybrid DC transmission delivery system.

11. A computer device, comprising: The application further provides a computer device, which comprises a memory and a processor, the memory and the processor are mutually connected in communication, the memory stores computer instructions, and the processor executes the computer instructions to execute the steps of the starting control method of the new energy hybrid DC transmission delivery system according to any one of claims 1-9.

12. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the starting control method of the new energy hybrid DC transmission delivery system according to any one of claims 1-9.

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