Method and device for controlling energy consumption device in flexible direct current power transmission system

Abstract

The invention provides a control method and device for an energy consumption device in a flexible direct-current power transmission system, is suitable for the technical field of offshore wind power, and can effectively improve the fault ride-through capability and operation stability of a direct-current power generation system. The low-frequency control method for the flexible chopping type direct-current energy dissipation device comprises the steps that the bus voltage and the bus current of a direct-current power generation system are obtained, the bus voltage and the bus current are used for determining the surplus power of the direct-current power generation system, and the surplus power is the difference value between the output power of the direct-current power generation system and the input power of an alternating-current system; according to the surplus power and the bus voltage of the direct-current power generation system, the duty ratio of an energy consumption valve switching signal in the direct-current energy consumption device is determined; according to the duty ratio of the energy consumption valve switching signal, a switching strategy of the direct current energy consumption device is determined, and the switching strategy is used for switching on or switching off the direct current energy consumption device to consume surplus power.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore wind power, and in particular relates to a control method and device for an energy consumption device in a flexible direct current transmission system. Background Art

[0002] Flexible high-voltage direct current (HVDC) transmission (MMC-HVDC) is a transmission technology based on modular multilevel converter (MMC) technology. It has the characteristics of independent regulation of active and reactive power, passive power supply capability, and easy construction of DC power grid. It provides an efficient technical means for cluster power transmission of large-scale long-distance distributed offshore wind farms.

[0003] For the offshore wind farm MMC-HVDC grid-connected system, when the AC system fault of the receiving power grid causes the AC voltage to drop, the active power transmitted by the grid side converter (grid side MMC, GSMMC) to the receiving power grid will decrease accordingly. If the wind turbine captures wind energy and the active power emitted remains unchanged at this time, and the active power transmitted by the wind farm to the wind farm side converter (wind farmsMMC WFMMC) remains unchanged, then unbalanced power will be generated in the entire AC / DC conversion system, which will charge the capacitor of the MMC energy-consuming sub-module, causing the DC voltage of the overhead line to rise rapidly, thereby affecting the safe and stable operation of the MMC-HVDC. At this time, the AC voltage at the wind farm outlet will also be distorted, and the energy will be converted into kinetic energy and temporarily stored in the rotor. The rotor speed continues to increase, and in severe cases, it will cause the wind turbine to be disconnected from the grid.

[0004] In order to improve the continuous operation capability of offshore wind farms and avoid frequent disconnection of offshore wind turbines, it is necessary to ensure that offshore wind turbines continue to operate online during the instantaneous short-circuit fault of the onshore AC system. Therefore, how to improve the fault ride-through capability in the event of an onshore AC system fault has become a hot research topic in the field of MMC-HVDC grid connection of offshore wind farms. Summary of the invention

[0005] The present invention provides a control method and device for an energy consumption device in a flexible direct current power transmission system, which can effectively improve the fault ride-through capability and operation stability of the direct current power generation system.

[0006] In view of the above problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, a method for controlling an energy consumption device in a flexible direct current transmission system is provided, comprising:

[0008] Obtaining a bus voltage and a bus current of a DC power generation system, wherein the bus voltage and the bus current are used to determine a surplus power of the DC power generation system, wherein the surplus power is a difference between an output power of the DC power generation system and an input power of an AC system;

[0009] Determine the duty cycle of the switch signal of the energy consumption valve in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system;

[0010] According to the duty cycle of the switch signal of the energy consumption valve, the switching strategy of the DC energy consumption device is determined, and the switching strategy is used to switch on or off the DC energy consumption device to consume surplus power.

[0011] Optionally, determining a switching strategy of a DC energy consumption device according to a duty cycle of a switch signal of an energy consumption valve includes:

[0012] An energy consumption valve switch signal is generated according to the duty cycle of the energy consumption valve switch signal. The energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume surplus power.

[0013] Furthermore, the duty cycle of the energy consumption valve switch signal satisfies:

[0014] D=D p +D u ,

[0015] D p =P on / P N ,

[0016] P on =P N -P m ,

[0017] P m =U m *I m ,

[0018]

[0019] Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D u is the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E abis the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

[0020] Optionally, before determining the duty cycle of the switch signal of the energy consumption valve in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system, the method further includes:

[0021] When the DC voltage measurement value exceeds the action voltage value set by the DC energy consuming device, the energy consuming device receives an action instruction issued by the DC control protection system or the valve pole control system of the energy consuming device.

[0022] In a second aspect, a low-frequency control device for a flexible chopping DC energy consuming device is provided, comprising: an acquisition module and a determination module; wherein:

[0023] An acquisition module is used to acquire the bus voltage and bus current of the DC power generation system, where the bus voltage and bus current are used to determine the surplus power of the DC power generation system, where the surplus power is the difference between the output power of the DC power generation system and the input power of the AC system;

[0024] A determination module, used to determine the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system;

[0025] The determination module is also used to determine the switching strategy of the DC energy consuming device according to the duty cycle of the energy consuming valve switch signal. The switching strategy is used to switch on or off the DC energy consuming device to consume surplus power.

[0026] Optionally, the determination module is further used to generate an energy consumption valve switch signal according to the duty cycle of the energy consumption valve switch signal, and the energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume surplus power.

[0027] Furthermore, the duty cycle of the energy consumption valve switch signal satisfies:

[0028] D=D p +D u ,

[0029] D p =P on / P N ,

[0030] P on =P N -P m ,

[0031] P m =U m *I m ,

[0032]

[0033] Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D u is the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E ab is the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

[0034] Optionally, the low-frequency control device of the flexible chopper type DC energy consumption device further includes: a receiving module; wherein,

[0035] The receiving module is used to determine the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system. When the DC voltage measurement value exceeds the action voltage value set by the DC energy consumption device, the energy consumption device receives the start-up action instruction issued by the DC control protection system or the valve pole control system of the energy consumption device.

[0036] In a third aspect, an electronic device is provided, comprising: a processor, the processor being coupled to a memory;

[0037] The processor is used to read and execute the program or instruction stored in the memory, so that the electronic device executes the low-frequency control method of the flexible chopper type DC energy consumption device described in the first aspect.

[0038] In a fourth aspect, a computer-readable storage medium is provided, which stores a program or instruction. When a computer reads and executes the program or instruction, the computer executes the low-frequency control method of the flexible chopper type DC energy consumption device described in the first aspect.

[0039] Based on the control method, control device and equipment of the energy consumption device in the flexible direct current transmission system provided by the present invention, the surplus power of the direct current power generation system can be determined according to the bus voltage and bus current of the direct current power generation system, and then the duty cycle of the energy consumption valve switch signal in the direct current energy consumption device is determined by comprehensively considering the surplus power and bus voltage of the direct current power generation system, and the switching strategy of the direct current energy consumption device is determined according to the duty cycle of the energy consumption valve switch signal to consume the surplus power of the direct current power generation system, thereby avoiding the problem that when the AC system of the receiving-end power grid fails and causes the AC voltage to drop, the bus voltage of the direct current power generation system increases, thereby affecting the stable operation of the direct current power generation system, and even disconnecting from the grid in severe cases, and can effectively improve the fault ride-through capability and operation stability of the direct current power generation system.

[0040] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 An electrical topology diagram of a centralized energy consumption device according to an embodiment of the present invention;

[0043] Figure 2 is a current path diagram when the switch Km is turned on in the IGCT module of the embodiment of the present invention;

[0044] Figure 3 is a current path diagram when the switch Km in the IGCT module of the embodiment of the present invention is turned off;

[0045] Figure 4 A schematic flow chart of a method for controlling an energy consumption device in a flexible direct current transmission system provided by an embodiment of the present invention;

[0046] Figure 5 A block diagram of the duty cycle modulation principle provided by an embodiment of the present invention;

[0047] Figure 6 A control block diagram of a submodule control link provided in an embodiment of the present invention;

[0048] Figure 7A simulation schematic diagram of a 90% duty cycle at a 21 Hz operating frequency provided by an embodiment of the present invention;

[0049] Figure 8 A simulation schematic diagram of a 40% duty cycle at a 21 Hz operating frequency provided by an embodiment of the present invention;

[0050] Fig. 9 A simulation schematic diagram of a 20% duty cycle at a 21 Hz operating frequency provided by an embodiment of the present invention;

[0051] Fig.10 A simulation schematic diagram of a 10 Hz operating frequency at a 90% duty cycle provided by an embodiment of the present invention;

[0052] Fig.11 A simulation schematic diagram of a 15 Hz operating frequency at a 90% duty cycle provided by an embodiment of the present invention;

[0053] Fig.12 A simulation schematic diagram of a 20 Hz operating frequency at a 90% duty cycle provided by an embodiment of the present invention;

[0054] Fig.13 A 50% surplus power energy consumption device response simulation waveform provided by an embodiment of the present invention;

[0055] Fig.14 An IGCT temperature rise curve provided by an embodiment of the present invention;

[0056] Fig.15 A schematic diagram of the structure of a device provided by an embodiment of the present invention;

[0057] Fig.16 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The electrical topology of centralized DC energy consumption device is as follows Figure 1 As shown, the energy-consuming device is mainly composed of energy-consuming valves and energy-consuming resistors. The two energy-consuming valves are arranged symmetrically and are respectively connected to the positive and negative poles of the busbar through current-limiting reactors; the energy-consuming resistors are arranged outdoors, and the two ends are respectively connected to the two energy-consuming valves.

[0060] like Figure 2 and 3 As shown, the energy-consuming valve is composed of several IGCT modules connected in series. The IGCT module consists of an IGCT (Km), a DC capacitor Ca, a current-limiting resistor Ra, a fast-recovery diode Dr, and a protective MOVs. As Figure 2 shown, when the switch Km is turned on, the IGCT module is put into operation, and the current mainly flows through the IGCT branch, denoted as It; conversely, as Figure 3 shown, when the switch Km is turned off, the IGCT module is cut out, and the current mainly flows through the Df, Ca branch, denoted as I d .

[0061] Combined with Figures 1 to 3 , two energy-consuming valves adopt a symmetric control strategy. Regardless of the value of the duty cycle (D, also known as the power command value), the number of IGCT modules put into each energy-consuming valve is the same; when the centralized DC energy-consuming device is in the hot standby state, all the main switches K of the IGCT modules m are turned off, and the DC pole line voltage U dc is evenly distributed on each sub-module. Therefore, the voltage U of each sub-module IGCT = U dc / N T (U dc is the DC pole line voltage, and N T is the total number of IGCT modules connected in series in the energy-consuming valve); when all the main switches K of the IGCT modules m are turned on, the DC pole line voltage is directly applied across the energy-consuming resistor. At this time, the absorbed power of the energy-consuming resistor is equal to the output power P of the DC system N .

[0062]

[0063] When the duty cycle received by the centralized DC energy-consuming device is D (0 < D < 1), the absorbed power P on is:

[0064]

[0065] Where: I ch is the total current flowing through the energy-consuming device.

[0066] The required duty cycle can be obtained as:

[0067]

[0068] The above derivation process shows that the power consumed by the energy-consuming device depends on the current of the energy-consuming branch, and the current of the energy-consuming branch is equal to the current of the energy-consuming resistor. Thus, by controlling the duty cycle of the current flowing through the energy-consuming resistor, the energy absorbed by the energy-consuming resistor can be adjusted, thereby controlling the power absorbed by the entire energy-consuming device.

[0069] Combine the following Figure 4-Figure 9 , a method for controlling energy-consuming devices in a flexible direct current transmission system provided by an embodiment of the present invention is described in detail.

[0070] like Figure 4 As shown, the control method of the energy consumption device in the flexible direct current transmission system includes:

[0071] S301, obtaining a bus voltage and a bus current of a DC power generation system, where the bus voltage and the bus current are used to determine a surplus power of the DC power generation system, where the surplus power is a difference between an output power of the DC power generation system and an input power of an AC system.

[0072] The bus voltage and bus current of the above DC power generation system can be collected by a voltmeter and an ammeter, and the input power of the AC system of the receiving power grid can be calculated to meet the following requirements:

[0073] P m =U m *I m (4)

[0074] Among them, P m is the input power of the receiving-end power grid AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system.

[0075] Assume that the rated output power of the DC power generation system is P N , when working normally, the actual output power P of the DC power generation system out Usually in P N Floating within a certain range, such as P N *90%≤P out ≤P N *110%, at this time the actual output power P of the DC power generation system out The input power P received by the receiving grid AC system m Roughly equivalent, that is, P m ≈P out . In other words, at this time, the electric energy generated by the DC power generation system is basically absorbed by the AC system of the receiving power grid to achieve an energy balance. There is no need to charge the capacitors in the MMC energy-consuming submodule, so the bus voltage of the DC power generation system will not rise and will stabilize within an acceptable range. In this article, the acceptable bus voltage deviation range of the DC power generation system is called the voltage fluctuation limit ΔU, which can be selected as 0.1 times the rated voltage, that is, ΔU = 0.1U N , which is 0.9U N ≤U m ≤1.1U N .

[0076] For example, the rated output power of a DC power generation system is P N =2000MW, the voltage fluctuation limit requires that the bus voltage value controlled by the energy-consuming device after startup can be: 900kV≤U m ≤1100kV, control system target voltage U ref =U N =1000kV.

[0077] However, when the AC system of the receiving grid fails, the output power P of the DC power generation system out Part or even all of it cannot be transmitted to the receiving grid. At this time, the input power P received by the AC system of the receiving grid is m will be less than the output power P of the DC power generation system out , that is, P m <P out , accordingly, the surplus power of the DC power generation system refers to the output power P of the DC power generation system out Exceeds the input power P received by the receiving grid AC system m To simplify the calculation, the rated output power P of the DC power generation system can be used. N Instead of the actual output power P of the DC power generation system out To calculate, that is, to satisfy:

[0078] P on =P N -P m (5)

[0079] Among them, P on is the surplus power of the DC power generation system, P m is the input power of the receiving-end power grid AC system, P N is the rated output power of the DC power generation system.

[0080] S302, determining a duty cycle of a switch signal of an energy consumption valve in a DC energy consumption device according to the surplus power and bus voltage of the DC power generation system;

[0081] Among them, the duty cycle of the energy consumption valve switch signal satisfies:

[0082] D=D p +D u (6)

[0083] D p =P on / P N (7)

[0084]

[0085] Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D u is the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E ab is the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

[0086] Optionally, before determining the duty cycle of the switch signal of the energy consumption valve in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system in S302, the method further includes:

[0087] When the DC voltage measurement value exceeds the action voltage value set by the DC energy consuming device, the energy consuming device receives an action instruction issued by the DC control protection system or the valve pole control system of the energy consuming device.

[0088] S303, determining a switching strategy of the DC energy consuming device according to the duty cycle of the energy consuming valve switch signal, wherein the switching strategy is used to switch the DC energy consuming device on or off to consume surplus power.

[0089] Optionally, S303, determining a switching strategy of a DC energy consumption device according to a duty cycle of a switch signal of an energy consumption valve, includes:

[0090] An energy consumption valve switch signal is generated according to the duty cycle of the energy consumption valve switch signal. The energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume surplus power.

[0091] Combine the following Figure 5 and Figure 6 To illustrate the specific implementation of S302 and S303.

[0092] like Figure 5 As shown, when the DC bus voltage measurement value U m Exceeds the action voltage value U set by the DC energy consumption device a When U m >U a, if the unlocking conditions of the DC energy consumption device are met, the DC energy consumption device collects the bus voltage and bus current of the DC power generation system and other electrical quantities according to the input action instructions issued by the DC control protection system or the valve pole control system of the energy consumption device, and determines the formulation and implementation of the switching strategy of the DC energy consumption device. The DC energy consumption device determines the working duty cycle of the DC energy consumption device according to the received bus voltage, bus current and rated working frequency of the DC energy consumption device, and generates the working pulse signal of the energy consumption valve of the DC energy consumption device.

[0093] Specifically, Figure 6 As shown in the figure, after the DC energy consumption device determines that the unlocking condition is met, it first collects the bus voltage and bus current of the DC power generation system and calculates the surplus power P of the current DC power generation system. on (Formula (4)-(5)), then unlock the DC voltage control link, and then according to the surplus power P on And DC voltage signal U m Calculate the duty cycle D of the energy consumption valve switch signal (Formula (6)-(8)) and control the DC voltage to stabilize at its target value U ref Within ±ΔU range.

[0094] It should be noted that according to the working principle of the DC energy dissipation device, when the duty cycle D is the reference duty cycle D p When D=D p When the DC energy consumption device absorbs and consumes the surplus power, the bus voltage of the DC power generation system will be stabilized at its rated voltage U N Considering factors such as system power loss, the surplus power P on The calculation cannot be completely accurate. At the same time, in order to ensure that the DC bus voltage closed loop is controllable and suitable for U ref ≠U N In the case of p Based on the measured value of the DC bus voltage U m The duty cycle D is further adjusted, that is, D = D p +D u , where the additional duty cycle D u The error U of the DC bus voltage relative to its reference value ref -U m Calculated by PID controller.

[0095] Combine the following Figure 7-Figure 14 The simulation results are given as examples.

[0096] Taking a certain offshore wind power DC grid-connected project as an example, a simulation model of DC energy consumption device is established. The bus voltage of the DC power generation system is plus or minus 500kV, the rated transmission power is 2000MW, the number of energy consumption valve submodules in series is 476 (excluding redundancy), and the rated working voltage of the IGCT module is 2kV.

[0097] Figure 7-Figure 9 The simulation results show that: assuming that the operating frequency of the DC energy consumption device remains unchanged (21Hz), under different surplus power conditions, the DC energy consumption device can be put into operation according to the instruction (the state quantity Eab becomes 1), and the corresponding duty cycle D is obtained according to the control strategy. The duty cycle signal consists of two parts. One part is the reference duty cycle D calculated based on the surplus power. p From the simulation results, we can see that this reference value is constant and the same as the per-unit value of the surplus power; the other part is the additional duty cycle D obtained by the closed-loop control of the bus voltage. u , can play a corrective role, so as to better control the bus voltage to be stable near the rated value. According to the duty cycle signal, the control signals Tu and Td of the IGCT device can be generated, so that the energy consumption valve is periodically turned on and off, and a DC current I similar to a square wave is generated on the DC energy consumption device. dc_DBR , the duty cycle of this current is approximately D. Therefore, under this control strategy, the DC energy consumption device is equivalent to a DC load with adjustable power consumption and a DC current flowing through it. It can adjust its own power consumption capacity according to the surplus power of the DC power generation system and the bus voltage to maintain the bus voltage stable near the rated value.

[0098] Figure 10-12 The simulation results show that when the duty cycle is constant (90%), by adjusting the operating frequency of the DC energy dissipation device, the equivalent energy passing through the entire DC energy dissipation device can change with the operating frequency, and the overall load characteristics of the DC energy dissipation device are also equivalent to a DC load with a DC current flowing through it and adjustable power consumption.

[0099] For example, Figure 8 As shown in the figure, when the receiving end converter station or AC system failure causes the system to have 50% surplus power, the DC energy consumption device is activated. The simulation waveform of the DC energy consumption device is as follows: Figure 8 As shown. The simulation results show that:

[0100] (1) The low-frequency control strategy is adopted to put the energy-consuming device into operation after the fault, and the peak value of the DC voltage between the poles does not exceed 1.06*Uref;

[0101] (2) Before the fault is cleared by adopting the low-frequency control strategy, under the action of the DC energy consumption device, the fluctuation range of the inter-pole DC voltage after entering the steady state should be within 0.94Uref~1.06Uref.

[0102] (3) The time interval T from the moment the fault starts to the moment the inter-electrode DC voltage begins to enter a steady state using the low-frequency control strategy s No more than 0.1s.

[0103] (4) After the low-frequency control strategy is adopted, the energy-consuming device will exit quickly and reliably after the fault is cleared. There will be no situation where the energy-consuming device cannot exit or is repeatedly put into and out of operation after the fault is cleared.

[0104] In addition, when the duty cycle approaches 100%, the IGCT loss is the largest; the curve of IGCT chip temperature rise versus operating time can be obtained as follows: Fig. 9 As shown, after 1.5s of continuous operation, the IGCT temperature rises to 30°C, so the IGCT maximum junction temperature is less than 85°C, and the maximum allowable instantaneous junction temperature of the selected IGCT is 125°C. Therefore, the IGCT maximum operating junction temperature is much lower than the upper limit of the junction temperature, and the safety margin is sufficient. The IGCT does not need to be connected in parallel or forced water cooling.

[0105] It should be noted that even if the receiving-end power grid does not fail, it is possible that surplus power is generated in the DC power generation system due to other reasons, such as a significant fluctuation in the load of the receiving-end power grid AC system. In this case, the control method for energy consumption devices in a flexible DC power transmission system provided by an embodiment of the present invention can still be used to consume the surplus power.

[0106] Based on the control method of the energy consumption device in the flexible direct current power transmission system provided by the present invention, the surplus power of the direct current power generation system can be determined according to the bus voltage and bus current of the direct current power generation system, and then the duty cycle of the energy consumption valve switch signal in the direct current energy consumption device is determined by comprehensively considering the surplus power and bus voltage of the direct current power generation system, and the switching strategy of the direct current energy consumption device is determined according to the duty cycle of the energy consumption valve switch signal to consume the surplus power of the direct current power generation system, thereby avoiding the problem that when the AC system of the receiving-end power grid fails and causes the AC voltage to drop, the bus voltage of the direct current power generation system increases, thereby affecting the stable operation of the direct current power generation system, and even disconnecting from the grid in severe cases, and can effectively improve the fault ride-through capability and operation stability of the direct current power generation system.

[0107] Combined with the above Figure 4-Figure 14 The control method of the energy consumption device in the flexible DC power transmission system provided by the embodiment of the present invention is described in detail. Fig.15 and Fig.16 The control device and the electronic device of the energy consumption device in the flexible direct current power transmission system provided by the embodiments of the present invention are respectively described.

[0108] For example, Fig.15The present invention also provides a schematic diagram of a control device for an energy-consuming device in a flexible DC power transmission system. The flexible chopper DC energy-consuming device low-frequency control device can execute the control method for an energy-consuming device in a flexible DC power transmission system described in the above method embodiment.

[0109] like Fig.15 As shown, the control device 1400 of the energy consumption device in the flexible direct current transmission system includes: an acquisition module 1401 and a determination module 1402; wherein,

[0110] An acquisition module 1401 is used to acquire a bus voltage and a bus current of a DC power generation system, where the bus voltage and the bus current are used to determine a surplus power of the DC power generation system, where the surplus power is the difference between the output power of the DC power generation system and the input power of the AC system;

[0111] The determination module 1402 is used to determine the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system;

[0112] The determination module 1402 is further used to determine a switching strategy of the DC energy consuming device according to the duty cycle of the energy consuming valve switch signal, and the switching strategy is used to switch on or off the DC energy consuming device to consume surplus power.

[0113] Optionally, the determination module 1402 is further used to generate an energy consumption valve switch signal according to the duty cycle of the energy consumption valve switch signal, and the energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume surplus power.

[0114] Furthermore, the duty cycle of the energy consumption valve switch signal satisfies:

[0115] D=D p +D u ,

[0116] D p =P on / P N ,

[0117] P on =P N -P m ,

[0118] P m =U m *I m ,

[0119]

[0120] Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D uis the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E ab is the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

[0121] Optionally, the control device 1400 for an energy consumption device in a flexible direct current transmission system further includes: a receiving module 1403; wherein,

[0122] The receiving module 1403 is used to determine the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power and bus voltage of the DC power generation system, and when the DC voltage measurement value exceeds the action voltage value set by the DC energy consumption device, the energy consumption device receives the start-up action instruction issued by the DC control protection system or the valve pole control system of the energy consumption device.

[0123] For example, Fig.16 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention.

[0124] like Fig.16 As shown, the electronic device 1500 includes: a processor 1501, the processor 1501 is coupled to a memory 1502;

[0125] The processor 1501 is used to read and execute the program or instruction stored in the memory 1502, so that the electronic device 1500 performs the following steps: Figure 4 The control method of energy consumption devices in the flexible direct current transmission system is shown.

[0126] Optionally, the electronic device 1500 may further include a transceiver 1503 for the electronic device 1500 to communicate with other devices.

[0127] It should be noted that, for the sake of convenience, Fig.15 and Fig.16 Only main components of the control device 1400 of the energy consumption device in the flexible DC power transmission system and the electronic device 1500 are shown. In practical applications, the control device 1400 of the energy consumption device in the flexible DC power transmission system and the electronic device 1500 may also include components or assemblies not shown in the figure.

[0128] An embodiment of the present invention further provides a computer-readable storage medium storing a program or instruction. When a computer reads and executes the program or instruction, the computer executes the method for controlling an energy consumption device in a flexible direct current transmission system described in the above method embodiment.

[0129] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling an energy consumption device in a flexible direct current transmission system, characterized in that: include: Obtaining a bus voltage and a bus current of a DC power generation system, wherein the bus voltage and the bus current are used to determine a surplus power of the DC power generation system, wherein the surplus power is a difference between an output power of the DC power generation system and an input power of an AC system; Determining a duty cycle of a switch signal of an energy consumption valve in a DC energy consumption device according to the surplus power of the DC power generation system and the bus voltage; According to the duty cycle of the energy consumption valve switch signal, the switching strategy of the DC energy consumption device is determined, and the switching strategy is used to switch on or off the DC energy consumption device to consume the surplus power.

2. The method for controlling energy consumption devices in a flexible direct current transmission system according to claim 1, characterized in that: Determining the switching strategy of the DC energy consumption device according to the duty cycle of the energy consumption valve switch signal includes: An energy consumption valve switch signal is generated according to the duty cycle of the energy consumption valve switch signal, and the energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume the surplus power.

3. The method for controlling energy consumption devices in a flexible direct current transmission system according to claim 2, characterized in that: The duty cycle of the energy consumption valve switch signal satisfies: D=D p +D u , D p =P on / P N , P on =P N -P m , P m =U m *AND m , Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D u is the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E ab is the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

4. The method for controlling an energy consumption device in a flexible direct current transmission system according to any one of claims 1 to 3, characterized in that: Before determining the duty cycle of the switch signal of the energy consumption valve in the DC energy consumption device according to the surplus power of the DC power generation system and the bus voltage, the method further includes: When the DC voltage measurement value exceeds the action voltage value set by the DC energy consuming device, the energy consuming device receives an action instruction issued by the DC control protection system or the valve pole control system of the energy consuming device.

5. A control device for an energy consumption device in a flexible direct current transmission system, characterized in that: include: Acquisition module and determination module; wherein, The acquisition module is used to acquire the bus voltage and bus current of the DC power generation system, wherein the bus voltage and bus current are used to determine the surplus power of the DC power generation system, and the surplus power is the difference between the output power of the DC power generation system and the input power of the AC system; The determination module is used to determine the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power of the DC power generation system and the bus voltage; The determination module is further used to determine a switching strategy of the DC energy consumption device according to the duty cycle of the energy consumption valve switch signal, and the switching strategy is used to switch on or off the DC energy consumption device to consume the surplus power.

6. The control device for energy consumption device in the flexible direct current transmission system according to claim 5, characterized in that: The determination module is further used to generate an energy consumption valve switch signal according to the duty cycle of the energy consumption valve switch signal, and the energy consumption valve switch signal is used to control the energy consumption valve of the DC energy consumption device to be turned on or off to consume the surplus power.

7. The control device for energy consumption device in flexible direct current transmission system according to claim 6, characterized in that: The duty cycle of the energy consumption valve switch signal satisfies: D=D p +D u , D p =P on / P N , P on =P N -P m , P m =U m *AND m , Where D is the duty cycle of the energy consumption valve switch signal, D p is the reference duty cycle of the energy consumption valve switch signal, D u is the additional duty cycle of the energy-consuming valve switch signal, P on is the surplus power, P N is the rated output power of the DC power generation system, P m is the input power of the AC system, U m is the bus voltage of the DC power generation system, I m is the bus current of the DC power generation system, U ref is the DC bus target voltage, E ab is the enabling state quantity of the energy-consuming device, T1 is the starting point of the data used in the integral link, T2 is the end point of the data used in the integral link, and k is the proportional control coefficient.

8. The control device for energy consumption device in the flexible direct current power transmission system according to any one of claims 5 to 7, characterized in that: Also includes: Receiving module; wherein, The receiving module is used for, before determining the duty cycle of the energy consumption valve switch signal in the DC energy consumption device according to the surplus power of the DC power generation system and the bus voltage, when the DC voltage measurement value exceeds the action voltage value set by the DC energy consumption device, the energy consumption device receives the start-up action instruction issued by the DC control protection system or the valve pole control system of the energy consumption device.

9. An electronic device, characterized in that: include: a processor coupled to the memory; The processor is used to read and execute the program or instruction stored in the memory, so that the electronic device executes the control method of the energy consumption device in the flexible direct current transmission system according to any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that: A program or instruction is stored, and when a computer reads and executes the program or instruction, the computer executes the control method of an energy consumption device in a flexible direct current transmission system according to any one of claims 1 to 4.

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