Offshore wind power sea-land integrated power transmission system alternating current fault ride-through method based on fan energy consumption

Abstract

The invention discloses an offshore wind power sea-land integrated power transmission system alternating current fault ride-through method based on fan energy consumption. Obtaining the alternating current drop depth of the fault receiving end converter station, the first current operation power of the fault receiving end converter station, the rated capacity of the non-fault receiving end converter station and the second current operation power of the non-fault receiving end converter station; determining the fault surplus power according to the alternating current drop depth and the first current operation power; determining a first absorbable surplus power of the non-fault receiving end converter station according to the rated capacity and the second current operation power; and according to the relationship between the first absorbable surplus power and the fault surplus power, cooperatively regulating and controlling a non-fault receiving end converter station and a fan energy consumption device of the offshore wind plant, and realizing alternating current fault ride-through. According to the invention, fault surplus power can be absorbed, alternating-current fault ride-through can be realized, and safe and stable operation of the offshore wind power sea-land integrated power transmission system can be maintained.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to an AC fault riding method of an offshore wind power integrated land and sea transmission system based on wind turbine energy consumption. Background Art

[0002] In the offshore wind power integrated sea-land transmission system, when the onshore AC power grid fails, the offshore wind power flexible direct current transmission system should have the ability to ride through the AC fault. When the onshore AC power grid fails, the offshore wind power flexible direct current transmission system will have a power surplus problem in a short period of time, and the DC voltage of each end converter station will jump rapidly, which will seriously affect the safe and stable operation of the DC system. Therefore, there is an urgent need for an offshore wind power integrated sea-land AC fault ride-through method to solve the power surplus and AC fault problems and maintain the safe and stable operation of the offshore wind power DC transmission system. Summary of the invention

[0003] The embodiment of the present invention provides an AC fault riding method for an offshore wind power integrated land and sea transmission system based on wind turbine energy consumption, which can avoid the voltage fluctuation problem of the offshore wind power integrated land and sea transmission system caused by power surplus during AC fault, solve the power surplus and achieve AC fault riding, and maintain the safe and stable operation of the offshore wind power integrated land and sea transmission system.

[0004] An embodiment of the present invention provides an AC fault ride-through method for an offshore wind power onshore integrated power transmission system based on wind turbine energy consumption, which is applied to an offshore wind power onshore integrated power transmission system. The offshore wind power onshore integrated power transmission system includes an offshore wind farm, an onshore converter station and a power grid. The offshore wind farm is connected to the onshore converter station, and the onshore converter station is connected to the power grid.

[0005] The AC fault ride-through method of the offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption comprises:

[0006] When an AC fault occurs in the power grid, the AC drop depth of the fault receiving-end converter station, the first current operating power of the fault receiving-end converter station, the rated capacity of the non-fault receiving-end converter station and the second current operating power of the non-fault receiving-end converter station are obtained;

[0007] Determine the fault surplus power according to the AC drop depth and the first current operating power;

[0008] Determining a first absorbable surplus power of the non-fault receiving-end converter station according to the rated capacity of the non-fault receiving-end converter station and the second current operating power;

[0009] According to the relationship between the first absorbable surplus power and the fault surplus power, the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm are coordinated and regulated to achieve AC fault ride-through.

[0010] Furthermore, the method of collaboratively regulating the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm according to the relationship between the first absorbable surplus power and the fault surplus power includes:

[0011] If the first absorbable surplus power is greater than the fault surplus power, the non-fault receiving-end converter station is controlled to absorb the fault surplus power to achieve AC fault ride-through;

[0012] If the first absorbable surplus power is less than the fault surplus power, and the first absorbable surplus power is not zero; according to the fault surplus power and the first absorbable surplus power, calculate the second absorbable surplus power to be absorbed by the wind turbine energy consumption device; according to the first absorbable surplus power and the second absorbable surplus power, regulate the non-fault receiving end converter station and the wind turbine energy consumption device to achieve AC fault ride-through;

[0013] If the first absorbable surplus power is zero, the fan energy consumption device is controlled to absorb the fault surplus power to achieve AC fault ride-through.

[0014] Furthermore, if the first absorbable surplus power is greater than the fault surplus power, controlling the non-fault receiving-end converter station to absorb the fault surplus power includes:

[0015] If the first absorbable surplus power is greater than the fault surplus power, a first regulation instruction is generated according to the fault surplus power, and the first regulation instruction is transmitted to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station absorbs the fault surplus power according to the first regulation instruction when receiving the first regulation instruction.

[0016] Furthermore, the method of regulating the non-fault receiving-end converter station and the wind turbine energy consumption device according to the first absorbable surplus power and the second absorbable surplus power includes:

[0017] generating a second control instruction according to the first absorbable surplus power, and transmitting the second control instruction to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station absorbs the fault surplus power equal to the first absorbable surplus power according to the second control instruction when receiving the second control instruction;

[0018] A third control instruction is generated according to the second absorbable surplus power, and the third control instruction is transmitted to the wind turbine energy consumption device, so that the wind turbine energy consumption device absorbs the remaining fault surplus power according to the third control instruction when receiving the third control instruction.

[0019] Furthermore, if the first absorbable surplus power is zero, controlling the wind turbine energy consumption device to absorb the fault surplus power includes:

[0020] If the first absorbable surplus power is zero, a fourth control instruction is generated according to the fault surplus power, and the fourth control instruction is transmitted to the wind turbine energy consumption device, so that the wind turbine energy consumption device absorbs the fault surplus power according to the fourth control instruction when receiving the fourth control instruction.

[0021] Furthermore, the offshore wind farm includes a plurality of wind turbines, and each wind turbine corresponds to a wind turbine energy consumption device.

[0022] Further, transmitting the third control instruction to the fan energy consumption device includes:

[0023] A plurality of fifth control instructions are generated according to the number of wind turbine energy consuming devices and the third control instruction, and each fifth control instruction is sent to each wind turbine energy consuming device respectively.

[0024] Furthermore, before generating a plurality of fifth control instructions according to the number of wind turbine energy consuming devices and the third control instruction, the method further includes:

[0025] Perform fault detection on all fan energy consuming devices and determine the number of fan energy consuming devices that are not faulty;

[0026] The method of generating a plurality of fifth control instructions according to the number of wind turbine energy consuming devices and the third control instruction, and sending each fifth control instruction to each wind turbine energy consuming device respectively, comprises:

[0027] A plurality of sixth control instructions are generated according to the number of non-faulty fan energy consuming devices and the third control instruction, and each sixth control instruction is sent to each non-faulty fan energy consuming device respectively.

[0028] Further, when receiving the third control instruction, the wind turbine energy consumption device absorbs the remaining fault surplus power according to the third control instruction, including:

[0029] When any fan energy consumption device receives the fifth control instruction, it obtains the fan output power of the fan corresponding to the fan energy consumption device at a moment before the AC failure and the rated capacity of the current fan energy consumption device;

[0030] The fan output power at the moment before the AC failure is multiplied by the fifth control instruction to obtain the second absorbable surplus power of the current fan energy consumption device;

[0031] The second absorbable surplus power of the current wind turbine energy consumption device is divided by the rated capacity of the current wind turbine energy consumption device to obtain the energy consumption action duty cycle of the current wind turbine energy consumption device;

[0032] Outputting a trigger pulse of the current fan energy consuming device according to the current energy consuming action duty cycle of the fan energy consuming device and the carrier of the current fan energy consuming device;

[0033] The current wind turbine energy consumption device is regulated according to the trigger pulse, so that the current wind turbine energy consumption device absorbs the fault surplus power.

[0034] Furthermore, the offshore wind power integrated land and sea transmission system also includes an offshore converter station, and the offshore converter station communicates with each wind turbine energy consumption device through a bidirectional ring network optical fiber channel.

[0035] The following beneficial effects are achieved by implementing the present invention:

[0036] The present invention provides an AC fault crossing method for an offshore wind power integrated land and sea transmission system based on wind turbine energy consumption. When an AC fault occurs in the power grid, after obtaining the AC drop depth of the fault receiving-end converter station, the first current operating power of the fault receiving-end converter station, the rated capacity of the non-fault receiving-end converter station and the second current operating power of the non-fault receiving-end converter station, the fault surplus power generated by the fault receiving-end converter station and the first absorbable surplus power of the non-fault receiving-end converter station are determined, and then the non-fault receiving-end converter station and the wind turbine energy consumption device of the offshore wind farm are coordinated and regulated according to the relationship between the two. Through the coordinated regulation, the non-fault receiving-end converter station and the wind turbine energy consumption device absorb the fault surplus power, thereby avoiding the problem of voltage fluctuation in the offshore wind power integrated land and sea transmission system caused by the power surplus during AC fault, solving the power surplus and realizing AC fault crossing, and maintaining the safe and stable operation of the offshore wind power integrated land and sea transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of an AC fault ride-through method for an offshore wind power integrated land-sea transmission system based on wind turbine energy consumption provided by an embodiment of the present invention.

[0038] Figure 2 It is a structural schematic diagram of a land-sea integrated power transmission system based on offshore wind power provided by an embodiment of the present invention.

[0039] Figure 3 The figure is a schematic diagram of the communication topology between an offshore converter station and an offshore wind farm provided by an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of a first delay situation provided by an embodiment of the present invention.

[0041] Figure 5 It is a schematic diagram of a second delay situation provided by an embodiment of the present invention.

[0042] Figure 6 It is a schematic diagram of sending a control instruction provided by an embodiment of the present invention.

[0043] Figure 7 This is a trigger pulse determination flow chart provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0045] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0047] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0050] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0051] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0052] like Figure 1 As shown, an AC fault ride-through method for an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption is provided in an embodiment of the present invention, and is applied to Figure 2 The offshore wind power integrated land and sea transmission system shown.

[0053] In a preferred embodiment, the offshore wind power integrated land and sea transmission system further comprises an offshore converter station, and the offshore converter station communicates with each wind turbine energy consumption device via a bidirectional ring network optical fiber channel.

[0054] In a preferred embodiment, the offshore wind farm includes a plurality of wind turbines, each of which corresponds to a wind turbine energy consumption device.

[0055] Specifically, Figure 2 As shown, the offshore wind power integrated land and sea transmission system includes an offshore wind farm, an offshore converter station, a terminal converter station, a switch collection station, an onshore converter station and a receiving power grid connected in series in sequence. The offshore wind farm includes a plurality of wind turbines and a plurality of wind power converters, each wind turbine is connected to a corresponding wind power converter, and each wind power converter includes a wind turbine energy consumption device. The offshore converter station and the terminal converter station are connected through a DC submarine cable, the terminal converter station and the switch collection station are connected through a DC submarine cable, and the switch collection station and the onshore converter station are connected through a DC overhead line. The offshore converter station is connected through the following Figure 3 The bidirectional ring network optical fiber channel shown in the figure communicates quickly with each wind turbine energy consumption device in the offshore wind farm. The onshore converter station includes two receiving-end converter stations, namely, a fault receiving-end converter station and a non-fault receiving-end converter station.

[0056] The AC fault ride-through method of the offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption comprises:

[0057] Step S1: when an AC fault occurs in the power grid, the AC drop depth of the fault receiving-end converter station, the first current operating power of the fault receiving-end converter station, the rated capacity of the non-fault receiving-end converter station and the second current operating power of the non-fault receiving-end converter station are obtained;

[0058] Step S2: determining the fault surplus power according to the AC drop depth and the first current operating power; determining the first absorbable surplus power of the non-fault receiving-end converter station according to the rated capacity of the non-fault receiving-end converter station and the second current operating power;

[0059] Step S3: Coordinately regulate the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm according to the relationship between the first absorbable surplus power and the fault surplus power to achieve AC fault ride-through.

[0060] Before explaining the above steps, it should be added that during AC fault, when the wind turbine energy consumption device is not involved, all full-bridge and half-bridge modules of the offshore converter station and the onshore converter station absorb the surplus power together. At this time, according to the rated operating state of the system and the maximum operating module voltage of the submodule, the maximum allowable delay time for absorbing the fault surplus power during the AC fault can be calculated. The corresponding calculation formula is as follows:

[0061]

[0062] Among them, t allow is the maximum allowable delay time for absorbing the surplus power of the fault; C is the capacitance value; V max is the maximum allowable module voltage; V norm is the rated module voltage; N full is the number of all voltage modules in the offshore converter station and the onshore converter station; P max is the maximum active power.

[0063] For example, as shown in the following table, the present invention refers to the actual requirements of the project and takes typical values ​​for t allow Calculate and get t according to the typical values ​​in the table below allow =36.91ms, that is, after an AC fault occurs, the maximum allowable delay time for absorbing the fault surplus power is 36.91ms. It is necessary to absorb the fault surplus power through the intervention of the wind turbine energy-consuming device or the non-fault receiving-end converter station within this delay time to achieve AC fault crossing, thereby reducing the system voltage fluctuation time and maintaining system stability. The existing offshore converter station needs to be forwarded through the offshore wind farm SCADA system before it can communicate with each wind turbine energy-consuming device. The current communication time is about hundreds of ms to several seconds. Therefore, the large communication delay seriously affects the stability of the system, and it is necessary to redesign the communication link between the offshore converter station and each wind turbine energy-consuming device so that the communication time needs to meet the calculated t allowIndicator requirements.

[0064] category Numeric Capacitor C 11mF <![CDATA[Maximum allowable module voltage V max > 2.6kV <![CDATA[Rated module voltage V norm > 2.1kV <![CDATA[The number of sending - end and receiving - end modules N full > 5712 <![CDATA[Maximum active power P max > 2000MW

[0065] The specific communication method of the DC transmission system under AC fault is as follows: the onshore converter station detects the fault, and transmits the fault signal to the offshore converter station control and protection system through the 100M inter-station communication channel between the onshore converter station and the offshore converter station. The offshore converter station DC control and protection system issues a control instruction to call the wind turbine energy consumption device, which is transmitted to the wind turbine energy consumption device corresponding to each wind turbine through the optical fiber channel of the collector submarine cable. It can be seen that the communication delay from the occurrence of the fault to the commissioning of the wind turbine energy consumption device mainly includes the following links: fault feature transmission delay, line fault detection and communication delay, offshore converter station-wind turbine communication delay and wind turbine energy consumption commissioning delay. Combined with the existing DC engineering construction and operation status, it can be calculated that when a fault occurs in the receiving end AC system, the transmission delay from the occurrence of the fault to the forwarding of the offshore converter station DC control and protection system is about 14ms. The specific delay situation is as follows Figure 4 shown.

[0066] use Figure 3 The bidirectional ring network optical fiber channel shown in the figure transmits signals, and can realize the control from the offshore converter station issuing instructions to the wind turbine energy consumption device being put into operation within 1ms. Specifically, the bidirectional ring network optical fiber channel includes: a first optical fiber, a second optical fiber, a third optical fiber and a fourth optical fiber.

[0067] The first transmitting end of the offshore converter station is connected to the first receiving end of the first communication forwarding device through the first optical fiber, the first transmitting ends of the remaining communication forwarding devices except the first communication forwarding device and the terminal communication forwarding device are sequentially connected to the first receiving end of the next communication forwarding device through the first optical fiber, and the first transmitting end of the terminal communication forwarding device is connected to the first receiving end of the offshore converter station through the first optical fiber;

[0068] The second transmitting end of the offshore converter station is connected to the second receiving end of the terminal communication forwarding device through the second optical fiber, and the second transmitting ends of the remaining communication forwarding devices except the first communication forwarding device and the terminal communication forwarding device are sequentially connected to the second receiving end of the previous communication forwarding device through the second optical fiber, and the second transmitting end of the first communication forwarding device is connected to the second receiving end of the offshore converter station through the second optical fiber;

[0069] The third transmitting end of the offshore converter station is connected to the third receiving end of the first communication forwarding device through the third optical fiber, the third transmitting ends of the remaining communication forwarding devices except the first communication forwarding device and the terminal communication forwarding device are sequentially connected to the third receiving end of the next communication forwarding device through the third optical fiber, and the third transmitting end of the terminal communication forwarding device is connected to the third receiving end of the offshore converter station through the third optical fiber;

[0070] The fourth transmitting end of the offshore converter station is connected to the fourth receiving end of the terminal communication forwarding device through a fourth optical fiber. The fourth transmitting ends of the remaining communication forwarding devices except the first communication forwarding device and the terminal communication forwarding device are connected to the fourth receiving end of the previous communication forwarding device in sequence through the fourth optical fiber. The fourth transmitting end of the first communication forwarding device is connected to the fourth receiving end of the offshore converter station through the fourth optical fiber.

[0071] Exemplary: Taking a case of n wind turbines, the offshore converter station sends the wind turbine energy consumption input instruction from the first transmitting end TX1 of the offshore converter station to the first receiving end RX1 of the communication forwarding device 1 through the first optical fiber. After receiving the signal, the first receiving end RX1 transmits the signal through the internal signal, and then sends it again through the first transmitting end TX1 of the communication forwarding device 1 through the first optical fiber to the first receiving end RX1 of the communication forwarding device 2. After being sent to the first receiving end RX1 of the communication forwarding device n in turn, after the internal signal transmission of the communication forwarding device n, the response signal of each communication forwarding device to the wind turbine energy consumption input instruction is sent to the first receiving end RX1 of the offshore converter station through the first transmitting end of the communication forwarding device n through the first optical fiber.

[0072] At the same time, the offshore converter station sends the wind turbine energy consumption input instruction from the second transmitting end TX2 to the second receiving end RX2 of the communication forwarding device n through the second optical fiber, and after the internal signal transmission of the communication forwarding device n, it is sent from the second transmitting end TX1 of the communication forwarding device n to the second receiving end RX2 of the communication forwarding device n-1 through the second optical fiber, and then sent to the second receiving end RX2 of the communication forwarding device 1 in turn. After the internal signal transmission of the communication forwarding device 1, the response signal of each communication forwarding device to the wind turbine energy consumption input instruction is transmitted to the second receiving end RX2 of the offshore converter station through the second transmitting end TX2 of the communication forwarding device 1 through the second optical fiber.

[0073] At the same time, the offshore converter station sends the wind turbine energy consumption input instruction from the third transmitting end TX3 of the offshore converter station to the third receiving end RX3 of the communication forwarding device 1 through the third optical fiber. After receiving the signal, the third receiving end RX3 transmits it through the internal signal, and again sends it to the third receiving end RX3 of the communication forwarding device 2 through the third transmitting end TX3 of the communication forwarding device 1 through the first transmitting optical fiber. After being sent to the third receiving end RX3 of the communication forwarding device n in turn, after the internal signal transmission of the communication forwarding device n, the response signal of each communication forwarding device to the wind turbine energy consumption input instruction is sent to the third receiving end RX3 of the offshore converter station through the first transmitting end of the communication forwarding device n through the third optical fiber.

[0074] At the same time, the offshore converter station sends the wind turbine energy consumption input instruction from the fourth transmitting end TX4 to the fourth receiving end RX4 of the communication forwarding device n through the fourth optical fiber, and after the internal signal transmission of the communication forwarding device n, it is sent from the fourth transmitting end TX4 of the communication forwarding device n to the fourth receiving end RX4 of the communication forwarding device n-1 through the fourth optical fiber, and then sent to the fourth receiving end RX4 of the communication forwarding device 1 in turn, and after the internal signal transmission of the communication forwarding device 1, the response signal of each communication forwarding device to the wind turbine energy consumption input instruction is transmitted to the fourth receiving end RX4 of the offshore converter station through the fourth optical fiber through the fourth transmitting end TX4 of the communication forwarding device 1.

[0075] Based on the above communication delays, the maximum allowable delay for absorbing the fault surplus power and the auxiliary signal transmission of the above-mentioned two-way ring network optical fiber channel, after the AC fault occurs, the fault signal is transmitted to the input of the wind turbine energy consumption device, and the AC grid fault delay at the receiving end is about 15ms, achieving fast communication. The specific communication delay of calling the wind turbine energy consumption device is as follows Figure 5 shown.

[0076] For step S1 and step S2, when an AC fault occurs in the receiving-end power grid, the output power of the faulty receiving-end converter station corresponding to the receiving-end power grid is reduced, generating fault surplus power. At this time, it is necessary to obtain the AC drop depth and the first current operating power of the faulty receiving-end converter station, and obtain the rated capacity and the second current operating power of the non-faulty receiving-end converter station. The fault surplus power of the faulty receiving-end converter station can be calculated based on the AC drop depth and the first current operating power of the faulty receiving-end converter station. The generation of this fault surplus power is the cause of the AC fault in the power grid. After absorbing this fault surplus power, AC fault crossing can be achieved. Exemplarily, the output power of the faulty receiving-end converter station is 3000MW during normal operation. After an AC fault occurs in the power grid, the output power of the faulty receiving-end converter station is 2000MW. At this time, the fault surplus power is 1000MW.

[0077] Further, based on the rated capacity of the non-fault receiving-end converter station and the second current operating power, the power that the non-fault receiving-end converter station can still absorb (i.e., the above-mentioned first absorbable surplus power) can be calculated. The first absorbable surplus power includes positive and negative values. If the first absorbable surplus power is not zero, it is considered absorbable. For example, assuming that the rated capacity of the non-fault receiving-end converter station is 3000MW, and the second current operating power output by the non-fault receiving-end converter station is 2000MW, it can be known that the non-fault receiving-end converter station still has 1000MW of absorbable surplus power. If the second current operating power of the non-fault receiving-end converter station is -2000MW, it means that the non-fault receiving-end converter station needs to absorb power from the outside at this time, and the absorbable surplus power is 0 at this time.

[0078] For step S3, according to the relationship between the first absorbable surplus power and the fault surplus power, the non-fault receiving-end converter station and the wind turbine energy consumption device are coordinated and regulated to realize inter-station fault surplus power absorption through the non-fault receiving-end converter station, or realize out-of-station fault surplus power absorption through the wind turbine energy consumption device, or realize fault surplus power absorption through the non-fault receiving-end converter station and the wind turbine energy consumption device, thereby realizing AC fault riding.

[0079] The collaborative control logic is described in detail below.

[0080] In a preferred embodiment, the method of collaboratively regulating the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm according to the relationship between the first absorbable surplus power and the fault surplus power includes:

[0081] S301: If the first absorbable surplus power is greater than the fault surplus power, control the non-fault receiving-end converter station to absorb the fault surplus power to achieve AC fault ride-through;

[0082] S302: if the first absorbable surplus power is less than the fault surplus power, and the first absorbable surplus power is not zero, the first absorbable surplus power is used; according to the fault surplus power and the first absorbable surplus power, the second absorbable surplus power to be absorbed by the wind turbine energy consumption device is calculated; according to the first absorbable surplus power and the second absorbable surplus power, the non-fault receiving end converter station and the wind turbine energy consumption device are regulated to realize AC fault ride-through;

[0083] S303: If the first absorbable surplus power is zero, control the fan energy consumption device to absorb the fault surplus power to achieve AC fault ride-through.

[0084] For S301, in a preferred embodiment, if the first absorbable surplus power is greater than the fault surplus power, controlling the non-fault receiving-end converter station to absorb the fault surplus power includes: if the first absorbable surplus power is greater than the fault surplus power, generating a first control instruction according to the fault surplus power, and transmitting the first control instruction to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station absorbs the fault surplus power according to the first control instruction when receiving the first control instruction.

[0085] Specifically, assuming that the first absorbable surplus power is 2000MW and the fault surplus power is 1000MW, the first absorbable surplus power is greater than the fault surplus power at this time, that is, the fault surplus power generated by the fault receiving-end converter station can be completely absorbed by the non-fault receiving-end converter station. At this time, there is no need to activate the wind turbine energy consumption device. A first control instruction is directly generated according to the fault surplus power, and the first control instruction is sent to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station controls the operating power of the non-fault receiving-end converter station through the first control instruction, so that it absorbs all the fault surplus power generated by the fault receiving-end converter station.

[0086] Preferably, on the basis that the first absorbable surplus power is greater than the fault surplus power, it is necessary to further determine whether the AC section connecting the non-fault receiving-end converter station and the power grid meets the AC section requirement for transmission. If so, the non-fault receiving-end converter station is controlled to absorb the fault surplus power according to the above instructions; if not, the wind turbine energy consumption device is controlled to absorb the fault surplus power according to step S303.

[0087] For S302, when the first absorbable surplus power is less than the fault surplus power and the first absorbable surplus power is not zero, assuming that the first absorbable surplus power is 500MW and the fault surplus power is 1000MW, it can be seen that the non-fault receiving end converter station can absorb 500MW of fault surplus power, and the remaining 500MW of fault surplus power needs to be absorbed by the wind turbine energy consumption device, that is, the second absorbable surplus power is 500MW.

[0088] In a preferred embodiment, the regulation of the non-fault receiving-end converter station and the wind turbine energy consumption device according to the first absorbable surplus power and the second absorbable surplus power includes: generating a second regulation instruction according to the first absorbable surplus power, and transmitting the second regulation instruction to the non-fault receiving-end converter station, so that when the non-fault receiving-end converter station receives the second regulation instruction, it absorbs the fault surplus power equal to the first absorbable surplus power according to the second regulation instruction; generating a third regulation instruction according to the second absorbable surplus power, and transmitting the third regulation instruction to the wind turbine energy consumption device, so that when the wind turbine energy consumption device receives the third regulation instruction, it absorbs the remaining fault surplus power according to the third regulation instruction.

[0089] Specifically, a second control instruction is generated according to the first absorbable surplus power of 500MW, and the second control instruction is transmitted to the non-fault receiving end converter station, so that the non-fault receiving end converter station absorbs 500MW of fault surplus power according to the second control instruction. At the same time, a third control instruction is generated according to the second absorbable surplus power of 500MW, and the third control instruction is sent to the offshore converter station, and the third control instruction is sent to the wind turbine energy consumption device through the bidirectional ring network optical fiber channel between the offshore converter station and the wind turbine energy consumption device.

[0090] Preferably, when the fault surplus power needs to be absorbed by the non-fault receiving-end converter station, it is still necessary to determine whether the AC section of the non-fault receiving-end converter station meets the AC section requirement for transmission. If so, the non-fault receiving-end converter station is controlled to absorb 500MW of fault surplus power according to the above instructions; if not, the wind turbine energy consumption device is controlled to absorb all fault surplus power according to step S303.

[0091] In a preferred embodiment, transmitting the third control instruction to the fan energy consuming device includes: generating a plurality of fifth control instructions according to the number of fan energy consuming devices and the third control instruction, and sending each fifth control instruction to each fan energy consuming device respectively.

[0092] Specifically, Figure 6 As shown, considering the situation that there are multiple wind turbines in the offshore wind farm, each wind turbine corresponding to the wind power converter includes a wind turbine energy consumption device, that is, when absorbing the fault surplus power, it is absorbed by multiple wind turbine energy consumption devices. After transmitting the third control instruction to the offshore converter station, the offshore converter station generates multiple fifth control instructions based on the third control instruction and the number of wind turbine energy consumption devices to be allocated, and distributes each fifth control instruction to the corresponding wind turbine energy consumption device. Exemplarily, if there are 4 wind turbines, and the third control instruction indicates that the second absorbable surplus power is 500MW, then each fifth control instruction generated should control the energy consumption device corresponding to the wind turbine to absorb 125MW of fault surplus power.

[0093] In a preferred embodiment, before generating several fifth control instructions based on the number of fan energy consuming devices and the third control instruction, it also includes: performing fault detection on all fan energy consuming devices to determine the number of non-faulty fan energy consuming devices; the generating several fifth control instructions based on the number of fan energy consuming devices and the third control instruction, and sending each fifth control instruction to each fan energy consuming device respectively, includes: generating several sixth control instructions based on the number of non-faulty fan energy consuming devices and the third control instruction, and sending each sixth control instruction to each non-faulty fan energy consuming device respectively.

[0094] Specifically, considering that each fan energy consumption device may have a fault problem, before sending instructions to each fan energy consumption device for regulation, each fan energy consumption device may be subjected to fault detection, for example, obtaining the operating status of the fan corresponding to each fan energy consumption device, so as to determine whether the corresponding fan is faulty. For a fan with a fault, the fan energy consumption device of the fan is not called, and only the fan energy consumption device corresponding to the fan without a fault is called. Therefore, after fault detection, it is first necessary to determine the number of fan energy consumption devices that are not faulty, that is, operating normally, and redistribute the fault surplus power that each normally operating fan energy consumption device needs to absorb according to the number and the second absorbable surplus power in the third regulation instruction. Exemplarily, the second absorbable surplus power is 500MW, which includes a total of 4 wind turbine energy consumption devices, 2 of which are faulty, and the remaining 2 wind turbine energy consumption devices are not faulty. At this time, the second absorbable surplus power of 500MW is distributed to the remaining 2 wind turbine energy consumption devices, that is, 2 sixth control instructions are generated, and each sixth control instruction instructs the wind turbine energy consumption device to absorb 250MW of fault surplus power.

[0095] In a preferred embodiment, when the wind turbine energy consumption device receives the third control instruction, it absorbs the remaining fault surplus power according to the third control instruction, including: when any wind turbine energy consumption device receives the fifth control instruction, it obtains the wind turbine output power of the wind turbine corresponding to the wind turbine energy consumption device at the moment before the AC fault and the rated capacity of the current wind turbine energy consumption device; multiplies the wind turbine output power at the moment before the AC fault by the fifth control instruction to obtain the second absorbable surplus power of the current wind turbine energy consumption device; divides the second absorbable surplus power of the current wind turbine energy consumption device by the rated capacity of the current wind turbine energy consumption device to obtain the energy consumption action duty cycle of the current wind turbine energy consumption device; outputs a trigger pulse of the current wind turbine energy consumption device according to the energy consumption action duty cycle of the current wind turbine energy consumption device and the carrier of the current wind turbine energy consumption device; and controls the current wind turbine energy consumption device according to the trigger pulse so that the current wind turbine energy consumption device absorbs the fault surplus power.

[0096] Specifically, for any received control instruction (the control instruction may be the third control instruction, the fourth control instruction, the fifth control instruction and the sixth control instruction), for example, when the fifth control instruction is received, Figure 7 As shown, firstly, the fan output power P of the current fan energy consumption device before the AC fault is obtained through the sample and hold device of the fan energy consumption device. _ h old and the rated capacity P of the current fan energy consumption device _c h opper , with P _diss1 Indicates the fifth control instruction, the sample-and-hold output P _ h old After that, P _ h old Multiply by P _diss1 , get the second absorbable surplus power of the current wind turbine energy consumption device, and then divide it by P _c h opper Obtain the energy consumption action duty cycle of the current fan energy consumption device. Output a trigger pulse of the fan energy consumption device after comparing the energy consumption action duty cycle with the carrier of the fan energy consumption device, and regulate the current fan energy consumption device according to the trigger pulse so that the current fan energy consumption device absorbs the fault surplus power.

[0097] For S303, the absorbable surplus power is zero, that is, all fault surplus power must be absorbed by the fan energy consumption device. At this time, the fan energy consumption device is controlled to absorb all fault surplus power.

[0098] In a preferred embodiment, if the absorbable surplus power is zero, controlling the wind turbine energy consuming device to absorb the fault surplus power includes: if the absorbable surplus power is zero, generating a fourth control instruction according to the fault surplus power, and transmitting the fourth control instruction to the wind turbine energy consuming device, so that the wind turbine energy consuming device absorbs the fault surplus power according to the fourth control instruction when receiving the fourth control instruction.

[0099] Specifically, if the absorbable surplus power is zero, it indicates that the non-fault receiving converter station does not participate in the absorption of the fault surplus power. At this time, the fourth control instruction is generated and sent to the offshore converter station. The fourth control instruction is transmitted to the wind turbine energy consumption device through the bidirectional ring network optical fiber channel between the offshore converter station and the offshore wind farm, so that the wind turbine energy consumption device absorbs all the fault surplus power according to the fourth control instruction. Preferably, in the case where there are multiple wind turbine energy consumption devices, it is also necessary to calculate the fault surplus power that each wind turbine energy consumption device needs to absorb separately, and convert and distribute the fourth control instruction, which will not be repeated here. Similarly, in the case where there is a wind turbine energy consumption device failure among multiple wind turbine energy consumption devices, it is also necessary to determine the number of normally operating wind turbine energy consumption devices, and then convert and distribute the fourth control instruction according to the number of normally operating wind turbine energy consumption devices. The distribution object is the wind turbine energy consumption device that is not faulty, which will not be repeated here.

[0100] After the surplus power caused by the fault is absorbed by the wind turbine energy consumption device, each wind turbine energy consumption device is controlled to exit operation and DC power transmission is restored to reduce intervention in the system.

[0101] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An AC fault ride-through method for an offshore wind power integrated land-sea power transmission system based on wind turbine energy consumption, characterized in that: Applied to an offshore wind power sea-land integrated power transmission system, the offshore wind power sea-land integrated power transmission system comprises an offshore wind farm, an onshore converter station and a power grid, the offshore wind farm is connected to the onshore converter station, and the onshore converter station is connected to the power grid; The AC fault ride-through method of the offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption comprises: When an AC fault occurs in the power grid, the AC drop depth of the fault receiving-end converter station, the first current operating power of the fault receiving-end converter station, the rated capacity of the non-fault receiving-end converter station and the second current operating power of the non-fault receiving-end converter station are obtained; Determine the fault surplus power according to the AC drop depth and the first current operating power; determine the first absorbable surplus power of the non-fault receiving-end converter station according to the rated capacity and the second current operating power; According to the relationship between the first absorbable surplus power and the fault surplus power, the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm are coordinated and regulated to achieve AC fault ride-through.

2. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption according to claim 1, characterized in that: The method of collaboratively regulating the wind turbine energy consumption devices of the non-fault receiving-end converter station and the offshore wind farm according to the relationship between the first absorbable surplus power and the fault surplus power includes: If the first absorbable surplus power is greater than the fault surplus power, the non-fault receiving-end converter station is controlled to absorb the fault surplus power to achieve AC fault ride-through; If the first absorbable surplus power is less than the fault surplus power, and the first absorbable surplus power is not zero; according to the fault surplus power and the first absorbable surplus power, calculate the second absorbable surplus power to be absorbed by the wind turbine energy consumption device; according to the first absorbable surplus power and the second absorbable surplus power, regulate the non-fault receiving end converter station and the wind turbine energy consumption device to achieve AC fault ride-through; If the first absorbable surplus power is zero, the fan energy consumption device is controlled to absorb the fault surplus power to achieve AC fault ride-through.

3. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption according to claim 2, characterized in that: If the first absorbable surplus power is greater than the fault surplus power, controlling the non-fault receiving-end converter station to absorb the fault surplus power includes: If the first absorbable surplus power is greater than the fault surplus power, a first regulation instruction is generated according to the fault surplus power, and the first regulation instruction is transmitted to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station absorbs the fault surplus power according to the first regulation instruction when receiving the first regulation instruction.

4. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption as claimed in claim 3, characterized in that: The method of regulating the non-fault receiving-end converter station and the wind turbine energy consumption device according to the first absorbable surplus power and the second absorbable surplus power comprises: generating a second control instruction according to the first absorbable surplus power, and transmitting the second control instruction to the non-fault receiving-end converter station, so that the non-fault receiving-end converter station absorbs the fault surplus power equal to the first absorbable surplus power according to the second control instruction when receiving the second control instruction; A third control instruction is generated according to the second absorbable surplus power, and the third control instruction is transmitted to the wind turbine energy consumption device, so that the wind turbine energy consumption device absorbs the remaining fault surplus power according to the third control instruction when receiving the third control instruction.

5. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption as claimed in claim 4, characterized in that: If the first absorbable surplus power is zero, controlling the wind turbine energy consumption device to absorb the fault surplus power includes: If the first absorbable surplus power is zero, a fourth control instruction is generated according to the fault surplus power, and the fourth control instruction is transmitted to the wind turbine energy consumption device, so that the wind turbine energy consumption device absorbs the fault surplus power according to the fourth control instruction when receiving the fourth control instruction.

6. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption as claimed in claim 5, characterized in that: The offshore wind farm includes a plurality of wind turbines, each of which corresponds to a wind turbine energy consumption device.

7. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption according to claim 6, characterized in that: The transmitting the third control instruction to the fan energy consumption device includes: A plurality of fifth control instructions are generated according to the number of wind turbine energy consuming devices and the third control instruction, and each fifth control instruction is sent to each wind turbine energy consuming device respectively.

8. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption according to claim 7, characterized in that: Before generating a plurality of fifth control instructions according to the number of wind turbine energy consumption devices and the third control instruction, the method further includes: Perform fault detection on all fan energy consuming devices and determine the number of fan energy consuming devices that are not faulty; The method of generating a plurality of fifth control instructions according to the number of wind turbine energy consuming devices and the third control instruction, and sending each fifth control instruction to each wind turbine energy consuming device respectively, comprises: A plurality of sixth control instructions are generated according to the number of non-faulty fan energy consuming devices and the third control instruction, and each sixth control instruction is sent to each non-faulty fan energy consuming device respectively.

9. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption as claimed in claim 8, characterized in that: When receiving the third control instruction, the wind turbine energy consumption device absorbs the remaining fault surplus power according to the third control instruction, including: When any fan energy consumption device receives the fifth control instruction, it obtains the fan output power of the fan corresponding to the fan energy consumption device at the moment before the AC failure and the rated capacity of the current fan energy consumption device; The fan output power at the moment before the AC failure is multiplied by the fifth control instruction to obtain the second absorbable surplus power of the current fan energy consumption device; The second absorbable surplus power of the current wind turbine energy consumption device is divided by the rated capacity of the current wind turbine energy consumption device to obtain the energy consumption action duty cycle of the current wind turbine energy consumption device; Outputting a trigger pulse of the current fan energy consuming device according to the current energy consuming action duty cycle of the fan energy consuming device and the carrier of the current fan energy consuming device; The current wind turbine energy consumption device is regulated according to the trigger pulse, so that the current wind turbine energy consumption device absorbs the fault surplus power.

10. The AC fault ride-through method of an offshore wind power land-sea integrated power transmission system based on wind turbine energy consumption according to claim 9, characterized in that: The offshore wind power integrated land and sea transmission system also includes an offshore converter station, and the offshore converter station communicates with each wind turbine energy consumption device through a bidirectional ring network optical fiber channel.

Images