A frequency coordination control method based on variable speed wind turbines and FLC on both sides of the constant current

Abstract

The present invention relates to a frequency coordination control method based on a variable speed wind turbine and a normal direct double-side FLC, and belongs to the field of power system control technology. When an active power disturbance is detected in an asynchronous interconnected power grid of a wind power transmission system, it is determined whether the active power disturbance is an active power disturbance of the sending end system or an active power disturbance of the receiving end system. According to the frequency change amount in the disturbed area and the actual operation of the variable speed wind turbine, the FLC additional power instruction is adaptively set to improve the frequency stability of the asynchronous interconnected power grid while ensuring the safe and stable operation of the variable speed wind turbine. The purpose is to solve the problem of how to improve the frequency stability in the asynchronous interconnected power grid.

Description

Technical Field

[0001] The present application relates to the technical field of power system control, and in particular to a frequency coordination control method based on a variable speed wind turbine and a DC dual-side FLC. Background Art

[0002] With the continuous increase in the penetration rate of new energy and the entry of regional power grids into asynchronous interconnection, asynchronous interconnection is mainly used to solve the power instability problem caused by the large amount of DC power transfer caused by DC blocking in the AC / DC parallel system, but asynchronous interconnection will cause the inertia and frequency regulation ability of the power system to decrease significantly. Therefore, the frequency of the regional power grid system under asynchronous interconnection is closely related to the virtual inertia of variable-speed wind turbines and control characteristics such as primary frequency modulation and DC frequency modulation. Especially when power disturbances occur in different regions, the frequency of the power grid with weak inertia and low regulation ability should be ensured to be safe and stable, and the frequency regulation ability of the system and the utilization rate of frequency regulation resources should be fully improved.

[0003] Among the related technical solutions, the strategy currently commonly adopted is to add a power standby mode in the variable-speed wind turbine to perform multi-frequency control on the variable-speed wind turbine, or to set different dead zones and parameters in the FLC (Frequency Limit Controller) of the normal direct current double-sided FLC direct current transmission system to improve the frequency of the disturbed area.

[0004] However, multi-frequency control has different active power regulation and regulation speed for variable-speed wind turbines; if the FLC power regulation in the DC transmission system is too large, it will excessively affect the frequency stability of the weak inertia and low regulation capacity of the DC transmission system. Therefore, a frequency coordination control method is needed that can ensure the consistency of active power regulation and regulation speed in variable-speed wind turbines while not making excessive power regulation on the FLC in the DC double-side FLC DC transmission system, so as to improve the frequency stability in the asynchronous interconnected power grid.

[0005] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The main purpose of this application is to provide a frequency coordination control method based on variable speed wind turbines and constant direct current double-side FLC, aiming to solve the problem of how to improve the frequency stability in asynchronous interconnected power grids.

[0007] To achieve the above-mentioned purpose, the present application provides a frequency coordination control method based on a variable speed wind turbine and a DC double-side FLC, which is applied to a wind power transmission system. The wind power transmission system includes a DC double-side FLC DC system as a sending-end asynchronous power grid and a variable speed wind turbine as a receiving-end asynchronous power grid. The method includes the following steps:

[0008] Step S10, when an active power disturbance is detected in the asynchronous interconnected power grid of the wind power transmission system, determining whether the active power disturbance is an active power disturbance of a sending-end system or an active power disturbance of a receiving-end system;

[0009] Step S21: if it is the active power disturbance of the sending-end system, obtain the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the proportional coefficient of the maximum power tracking curve of the variable-speed wind turbine based on the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the first additional power of the variable-speed wind turbine based on the proportional coefficient and the current angular velocity of the wind turbine, so as to adjust the power of the variable-speed wind turbine based on the first additional power of the variable-speed wind turbine; and determine the first additional power of FLC based on the current angular velocity of the wind turbine, so as to adjust the power of the normally direct double-sided FLC DC system based on the first additional power of FLC;

[0010] Step S22: If the active power disturbance is in the receiving-end system, the power value output by the FLC after the receiving-end grid frequency disturbance is determined as the second additional power of the variable-speed wind turbine set, so as to adjust the power of the variable-speed wind turbine set based on the second additional power of the variable-speed wind turbine set; and the difference between the output power of the wind turbine set after releasing the frequency regulation standby and the current FLC output power is used as the second additional power of the FLC, so as to adjust the power of the normally direct double-sided FLC DC system based on the second additional power of the FLC.

[0011] Optionally, the calculation formula for the proportionality coefficient of the maximum power tracking curve of the variable speed wind turbine set is:

[0012]

[0013] Among them, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current fan angular velocity, Δf r is the frequency change of the power grid at the sending end, k opt is the scale factor of the initial maximum power tracking curve, is the initial angular velocity of the wind turbine; is the cutting angular velocity, is the angular velocity when entering the constant speed region, for The upper limit of the amplitude; P max is the upper limit of the fan output active power, η is the speed adjustment coefficient, , is the angular velocity increment, is the system synchronization angular velocity increment.

[0014] Optionally, the calculation formula of the first additional power of the variable speed wind turbine set is:

[0015]

[0016] Where ΔP w1 is the first additional power of the variable speed wind turbine, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current angular velocity of the fan, and P0 is the initial power of the fan.

[0017] Optionally, the calculation formula of the FLC first additional power is:

[0018]

[0019] Where ΔP add is the first additional power of FLC, k p , k i is the PI parameter, is the current fan angular velocity, is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

[0020] Optionally, after step S21, the method further includes:

[0021] Collect the current fan speed;

[0022] Calculating a current maximum wind energy utilization coefficient based on the current wind turbine speed and the first additional power of the variable speed wind turbine set, and calculating a first pitch angle according to the current maximum wind energy utilization coefficient; and calculating a second pitch angle based on the current wind turbine speed;

[0023] Determining a positive or negative value of a first additional power of the variable speed wind turbine generator set;

[0024] When the first additional power of the variable speed wind turbine generator set is a positive value, adjusting the pitch angle of the variable speed wind turbine generator set based on the larger value of the first pitch angle and the second pitch angle;

[0025] When the first additional power of the variable speed wind turbine generator set is a negative value, the pitch angle of the variable speed wind turbine generator set is adjusted based on a smaller value between the first pitch angle and the second pitch angle.

[0026] Optionally, the calculation formula for the current maximum wind energy utilization coefficient is:

[0027]

[0028] The calculation formula of the first pitch angle is:

[0029]

[0030] Among them, β1 is the first pitch angle, is the air density, R is the fan blade radius, and v is the wind speed.

[0031] Optionally, the calculation formula of the second pitch angle is:

[0032]

[0033] Where β2 is the second pitch angle, k p , k i is the PI parameter, is the current fan angular velocity, is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

[0034] Optionally, before the step of determining the FLC first additional power based on the current wind turbine angular velocity to adjust the power of the normally direct double-side FLC direct current system based on the FLC first additional power, the step further includes:

[0035] Determining whether the first additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0036] If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC first additional power;

[0037] Otherwise, return to the step of determining whether the first additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

[0038] Optionally, before the step of using the difference between the output power of the wind turbine after releasing the frequency regulation standby and the current FLC output power as the FLC second additional power to adjust the power of the normally direct double-side FLC DC system based on the FLC second additional power, the step further includes:

[0039] Determining whether the second additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0040] If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC second additional power;

[0041] Otherwise, return to the step of determining whether the second additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

[0042] In addition, to achieve the above-mentioned purpose, the present application also provides a wind power transmission system, which includes: a memory, a processor, and a frequency coordination control program based on variable speed wind turbines and FLC on both sides of the normal direct current stored in the memory and runnable on the processor. When the frequency coordination control program based on variable speed wind turbines and FLC on both sides of the normal direct current is executed by the processor, the steps of the frequency coordination control method based on variable speed wind turbines and FLC on both sides of the normal direct current are implemented as described in any of the above items. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the architecture of the hardware operating environment of the wind power transmission system involved in the embodiment of the present application;

[0044] Figure 2 This is a flow chart of the first embodiment of the frequency coordination control method based on variable speed wind turbines and constant direct current dual-side FLC of the present application;

[0045] Figure 3 This is a flow chart of the second embodiment of the frequency coordination control method based on the variable speed wind turbine and the constant direct current double-side FLC of the present application;

[0046] Figure 4 It is a schematic diagram of the dynamic response of the asynchronous interconnected power grid system when the sending end active power is disturbed;

[0047] Figure 5 Schematic diagram of the dynamic response of the asynchronous interconnected power grid system when the active power at the receiving end is disturbed.

[0048] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0049] In order to better understand the above technical solution, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0050] As an implementation plan, Figure 1 This is a schematic diagram of the architecture of the hardware operating environment of the wind power transmission system involved in the embodiment of the present application.

[0051] like Figure 1As shown, the wind power transmission system may include: a processor 1001, such as a CPU, a memory 1005, a user interface 1003, a network interface 1004, and a communication bus 1002. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory, or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0052] Those skilled in the art will understand that Figure 1 The wind power transmission system architecture shown in the figure does not constitute a limitation on the wind power transmission system, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0053] like Figure 1 As shown, the memory 1005 as a storage medium may include an operating system, a network communication module, a user interface module, and a frequency coordination control program based on variable-speed wind turbines and FLC on both sides of the constant direct current. Among them, the operating system is a program for managing and controlling the hardware and software resources of the wind power transmission system, and the operation of the frequency coordination control program based on variable-speed wind turbines and FLC on both sides of the constant direct current and other software or programs.

[0054] exist Figure 1 In the wind power transmission system shown, the user interface 1003 is mainly used to connect to the terminal and communicate data with the terminal; the network interface 1004 is mainly used for the background server and communicates data with the background server; the processor 1001 can be used to call the frequency coordination control program based on the variable speed wind turbine and the normal direct current double-side FLC stored in the memory 1005.

[0055] In this embodiment, the wind power transmission system includes: a memory 1005, a processor 1001, and a frequency coordination control program based on a variable speed wind turbine and a normal direct current double-side FLC stored in the memory and executable on the processor, wherein:

[0056] When the processor 1001 calls the frequency coordination control program based on the variable speed wind turbine and the normal direct current double-side FLC stored in the memory 1005, the following operations are performed:

[0057] Step S10, when an active power disturbance is detected in the asynchronous interconnected power grid of the wind power transmission system, determining whether the active power disturbance is an active power disturbance of a sending-end system or an active power disturbance of a receiving-end system;

[0058] Step S21: if it is the active power disturbance of the sending-end system, obtain the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the proportional coefficient of the maximum power tracking curve of the variable-speed wind turbine based on the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the first additional power of the variable-speed wind turbine based on the proportional coefficient and the current angular velocity of the wind turbine, so as to adjust the power of the variable-speed wind turbine based on the first additional power of the variable-speed wind turbine; and determine the first additional power of FLC based on the current angular velocity of the wind turbine, so as to adjust the power of the normally direct double-sided FLC DC system based on the first additional power of FLC;

[0059] Step S22: If the active power disturbance is in the receiving-end system, the power value output by the FLC after the receiving-end grid frequency disturbance is determined as the second additional power of the variable-speed wind turbine set, so as to adjust the power of the variable-speed wind turbine set based on the second additional power of the variable-speed wind turbine set; and the difference between the output power of the wind turbine set after releasing the frequency regulation standby and the current FLC output power is used as the second additional power of the FLC, so as to adjust the power of the normally direct double-sided FLC DC system based on the second additional power of the FLC.

[0060] When the processor 1001 calls the frequency coordination control program based on the variable speed wind turbine and the normal direct current double-side FLC stored in the memory 1005, the following operations are performed:

[0061] Collect the current fan speed;

[0062] Calculating a current maximum wind energy utilization coefficient based on the current wind turbine speed and the first additional power of the variable speed wind turbine set, and calculating a first pitch angle according to the current maximum wind energy utilization coefficient; and calculating a second pitch angle based on the current wind turbine speed;

[0063] Determining a positive or negative value of a first additional power of the variable speed wind turbine generator set;

[0064] When the first additional power of the variable speed wind turbine generator set is a positive value, adjusting the pitch angle of the variable speed wind turbine generator set based on the larger value of the first pitch angle and the second pitch angle;

[0065] When the first additional power of the variable speed wind turbine generator set is a negative value, the pitch angle of the variable speed wind turbine generator set is adjusted based on a smaller value between the first pitch angle and the second pitch angle.

[0066] When the processor 1001 calls the frequency coordination control program based on the variable speed wind turbine and the normal direct current double-side FLC stored in the memory 1005, the following operations are performed:

[0067] Determining whether the first additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0068] If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC first additional power;

[0069] Otherwise, return to the step of determining whether the first additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

[0070] When the processor 1001 calls the frequency coordination control program based on the variable speed wind turbine and the normal direct current double-side FLC stored in the memory 1005, the following operations are performed:

[0071] Determining whether the second additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0072] If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC second additional power;

[0073] Otherwise, return to the step of determining whether the second additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

[0074] Based on the hardware architecture of the wind power transmission system of the above-mentioned power system control technology, an embodiment of the present application based on a variable speed wind turbine and a dual-side FLC frequency coordination control method is proposed.

[0075] First embodiment

[0076] Reference Figure 2 In the first embodiment, the frequency coordination control method based on variable speed wind turbines and constant direct current double-side FLC includes the following steps:

[0077] Step S10, when an active power disturbance is detected in the asynchronous interconnected power grid of the wind power transmission system, determining whether the active power disturbance is an active power disturbance of a sending-end system or an active power disturbance of a receiving-end system;

[0078] In this embodiment, when an active power disturbance is detected in the asynchronous interconnected power grid of the wind power transmission system, it is determined whether the disturbance is an active power disturbance generated at the sending-end system or an active power disturbance generated at the receiving-end system.

[0079] The active power disturbance of the sending-end system is usually caused by problems on the power generation side. For example, the failure of the generator set at the sending end or the fluctuation of wind power generation will cause the active power disturbance of the sending-end system.

[0080] The active power disturbance generated at the receiving system is usually caused by changes on the load side. For example, large-scale industrial users turn on or off equipment at the same time, causing a rapid increase or decrease in active power demand; or a local power station in the receiving area fails, causing a large change in power, etc., which can easily cause active power disturbances at the receiving system.

[0081] Optionally, as to how to detect whether the active power disturbance is generated at the sending system or the receiving system, a synchronized phasor measurement unit can be used to monitor the voltage, frequency and phase angle of different nodes in the power grid in real time. If an active power disturbance occurs in the sending system, a significant change in frequency or phase angle is usually detected at a node close to the power station. If an active power disturbance occurs in the receiving system (such as a sudden increase in load), the frequency offset or voltage fluctuation will first appear near the load center.

[0082] Step S21, if it is a power disturbance of the sending-end system, obtain the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the proportional coefficient of the maximum power tracking curve of the variable-speed wind turbine based on the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the first additional power of the variable-speed wind turbine based on the proportional coefficient and the current angular velocity of the wind turbine, so as to adjust the power of the variable-speed wind turbine based on the first additional power of the variable-speed wind turbine; and determine the first additional power of FLC based on the current angular velocity of the wind turbine, so as to adjust the power of the normally direct double-side FLC DC system based on the first additional power of FLC;

[0083] In this embodiment, if it is detected that the active power disturbance is a power disturbance of the sending-end system, the power of the variable-speed wind turbine and the FLC DC system on both sides of the conventional DC are adjusted at the same time, and the output power of the wind turbine and the conventional DC is adaptively adjusted to reduce the frequency fluctuation in the active power disturbance area, so as to balance the frequency change of the asynchronous interconnected power grid caused by the power disturbance of the sending-end system.

[0084] For a variable-speed wind turbine set, a frequency change between the rated frequency of the sending-end power grid collected from the initial moment before the disturbance and the sending-end power grid frequency that jumps after the disturbance is generated is collected as the sending-end power grid frequency change, and the wind turbine angular velocity at the current moment is collected, and a first additional power of the variable-speed wind turbine set is calculated according to the sending-end power grid frequency change and the current wind turbine angular velocity, so as to adjust the power of the variable-speed wind turbine set based on the first additional power of the variable-speed wind turbine set;

[0085] Specifically and optionally, how to calculate the first additional power of the variable speed wind turbine according to the change in the frequency of the power grid at the sending end and the current angular velocity of the wind turbine, first, based on the change in the frequency of the power grid at the sending end and the current angular velocity of the wind turbine, calculate the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, wherein the calculation formula of the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine is:

[0086]

[0087] Among them, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current fan angular velocity, Δf r is the frequency change of the power grid at the sending end, k opt is the scale factor of the initial maximum power tracking curve, is the initial angular velocity of the wind turbine; is the cutting angular velocity, is the angular velocity when entering the constant speed region, for The upper limit of the amplitude; P max is the upper limit of the fan output active power, η is the speed adjustment coefficient, , is the angular velocity increment, is the system synchronization angular velocity increment.

[0088] After calculating the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine generator set, substitute it into the calculation formula of the first additional power of the variable speed wind turbine generator set to calculate the first additional power of the variable speed wind turbine generator set, wherein the calculation formula of the first additional power of the variable speed wind turbine generator set is:

[0089]

[0090] Where ΔP w1 is the first additional power of the variable speed wind turbine, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current angular velocity of the fan, and P0 is the initial power of the fan.

[0091] After calculating the first additional power of the variable speed wind turbine generator set, the power of the variable speed wind turbine generator set is controlled to adjust its own power to a value that satisfies the first additional power of the variable speed wind turbine generator set.

[0092] For the normally direct double-sided FLC direct current system, the FLC first additional power is calculated based on the collected current wind turbine angular velocity, so as to adjust the power of the normally direct double-sided FLC direct current system based on the FLC first additional power.

[0093] Specifically and optionally, how to calculate the first additional power of FLC, wherein the calculation formula of the first additional power of FLC is:

[0094]

[0095] Where ΔP add is the first additional power of FLC, k p , k i is the PI parameter, w r is the current fan angular velocity, w r0 is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

[0096] After the FLC first additional power is calculated, the normally direct double-side FLC direct current system is controlled to adjust its own power to a value that satisfies the FLC first additional power.

[0097] Step S22: If it is the power disturbance of the receiving-end system, the power value of the FLC output after the receiving-end grid frequency disturbance is determined as the second additional power of the variable-speed wind turbine set, so as to adjust the power of the variable-speed wind turbine set based on the second additional power of the variable-speed wind turbine set; and the difference between the output power of the wind turbine set after releasing the frequency regulation standby and the current FLC output power is used as the second additional power of the FLC, so as to adjust the power of the normally direct double-sided FLC DC system based on the second additional power of the FLC.

[0098] In this embodiment, if it is detected that the active power disturbance is a power disturbance of the receiving system, the power of the variable-speed wind turbine and the conventional DC double-side FLC DC system is also adjusted at the same time, and the output power of the wind turbine and the conventional DC is adaptively adjusted to reduce the frequency fluctuation in the active power disturbance area, so as to balance the frequency change of the asynchronous interconnected power grid caused by the power disturbance of the sending system.

[0099] Different from the power regulation method of the sending-end system, for the power regulation of the variable-speed wind turbine, in this embodiment, the power value output by the FLC after the receiving-end grid frequency disturbance is directly determined as the second additional power of the variable-speed wind turbine, and the variable-speed wind turbine is controlled to adjust its own power to a value that satisfies the second additional power of the wind turbine, that is:

[0100]

[0101] Where ΔP w2 is the second additional power of the variable speed wind turbine; ΔP flci It is the power output by FLC after the receiving grid frequency is disturbed.

[0102] For the power regulation of the FLC DC system on both sides of the DC, the difference between the output power of the wind turbine after releasing the frequency regulation reserve and the current FLC output power is used as the second additional power of the FLC, that is:

[0103]

[0104] Among them, P add2 is the second additional power of FLC; P wmax To release the frequency regulation reserve power of wind turbines. is the current FLC output power.

[0105] After the FLC second additional power is calculated, the normally direct double-side FLC direct current system is controlled to adjust its own power to a value that satisfies the FLC second additional power.

[0106] In the technical solution provided in this embodiment, the FLC additional power instruction is adaptively set according to the frequency change in the disturbed area and the actual operation of the variable speed wind turbine, so as to improve the frequency stability of the asynchronous interconnected power grid while ensuring the safe and stable operation of the variable speed wind turbine.

[0107] Second embodiment

[0108] Reference Figure 3 , based on the first embodiment, after step S21, the method further includes:

[0109] Step S31, collecting the current fan speed;

[0110] Step S41, calculating the current maximum wind energy utilization coefficient based on the current wind turbine speed and the first additional power of the variable speed wind turbine set, calculating the first pitch angle according to the current maximum wind energy utilization coefficient; and calculating the second pitch angle based on the current wind turbine speed;

[0111] Step S51, determining a positive or negative value of a first additional power of the variable speed wind turbine generator set;

[0112] Step S611, when the first additional power of the variable speed wind turbine generator set is a positive value, adjusting the pitch angle of the variable speed wind turbine generator set based on the larger value of the first pitch angle and the second pitch angle;

[0113] Step S612: when the first additional power of the variable speed wind turbine generator set is a negative value, adjusting the pitch angle of the variable speed wind turbine generator set based on the smaller value of the first pitch angle and the second pitch angle.

[0114] In this embodiment, when the grid power is disturbed, adjusting the pitch angle of the wind turbine can help adjust the power output of the wind turbine. By changing the relative angle between the blades and the wind, the efficiency of capturing wind energy can be changed, thereby adjusting the active power output of the wind turbine.

[0115] When the pitch angle increases, the wind energy capture efficiency decreases and the wind turbine output power decreases; when the wind speed allows, reducing the pitch angle can increase wind energy capture, thereby increasing the wind turbine power output. Therefore, when the grid has excess active power or the frequency is too high, adjusting the pitch angle can adjust the wind turbine power output and help the grid restore balance.

[0116] Specifically, the current calculation formula for the maximum utilization coefficient of wind energy is:

[0117]

[0118] Substitute the current maximum wind energy utilization coefficient into the first pitch angle calculation formula:

[0119]

[0120] Among them, β1 is the first pitch angle, is the air density, R is the fan blade radius, and v is the wind speed.

[0121] The first pitch angle can be calculated by substitution.

[0122] Specifically, for the second pitch angle, the calculation formula of the second pitch angle is:

[0123]

[0124] Where β2 is the second pitch angle, k p , k i is the PI parameter, is the current fan angular velocity, is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

[0125] Third embodiment

[0126] Based on any embodiment, in step S21, before the step of determining the FLC first additional power based on the current wind turbine angular velocity to adjust the power of the normally direct double-side FLC DC system based on the FLC first additional power, it also includes:

[0127] Step S211, determining whether the first additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0128] Step S212, if not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC first additional power;

[0129] Step S213: otherwise, return to the step of determining whether the first additional power of the variable speed wind turbine set is within the preset wind turbine output power limit interval.

[0130] In this embodiment, whether to start the first FLC additional power control is determined based on the numerical value of the variable speed fan additional power. If the first variable speed fan additional power is not within the preset fan output power limit range, it means that the frequency change of the sending end system is greater than the dead zone, and the first FLC additional power can be started.

[0131] Optionally, the preset wind turbine output power limit interval may be set to [-0.1P0, 0.06P0], where P0 is the initial power of the wind turbine.

[0132] Fourth embodiment

[0133] Based on any embodiment, in step S22, before the step of using the difference between the output power of the wind turbine after releasing the frequency regulation standby and the current FLC output power as the FLC second additional power to adjust the power of the normally direct double-side FLC DC system based on the FLC second additional power, it also includes:

[0134] Step S221, determining whether the second additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval;

[0135] Step S222, if not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC second additional power;

[0136] Step S223: otherwise, return to the step of determining whether the second additional power of the variable speed wind turbine set is within the preset wind turbine output power limit interval.

[0137] In this embodiment, whether to start the second FLC additional power control is determined based on the numerical value of the variable speed fan additional power. If the second variable speed fan additional power is not within the preset fan output power limit range, it means that the frequency change of the receiving system is greater than the dead zone, and the second FLC additional power can be started.

[0138] Optionally, the preset wind turbine output power limit interval may be set to [-0.1P0, 0.06P0], where P0 is the initial power of the wind turbine.

[0139] Fifth embodiment

[0140] In order to verify the effectiveness and correctness of the method of the present invention, this embodiment sets up a sudden increase in the load of the sending end system and a machine cut-off of the receiving end system for analysis, simulates the DC asynchronous interconnected power grid model containing the variable speed wind turbines, and obtains a simulation diagram under power disturbance, where: Figure 4 (1)- Figure 4 (4) are the dynamic responses of the asynchronous interconnected power grid system when the sending end active power is disturbed, Figure 5 (1)- Figure 5 (4) Dynamic response of the asynchronous interconnected power grid system when the active power at the receiving end is disturbed.

[0141] from Figure 4 (1)- Figure 4 It can be seen from (4) that the frequency coordination control based on variable speed fans and FLC on both sides of the DC has the best system frequency response characteristics and can significantly improve the frequency fluctuation in the active disturbance area. Compared with the control without additional control and FLC control, the inertia response of the variable speed fans and the participation of primary frequency modulation have a clear improvement effect on the frequency. The variable speed fans respond to the system frequency changes and quickly increase the active power. The frequency change at the sending end is the smallest and the frequency low point is the highest. The frequency change at the receiving end is smaller than that of FLC control. In addition, due to the FLC additional power control, the DC system can provide rapid and continuous support according to the real-time operating status of the fans, so the system frequency can be quickly and stably restored.

[0142] from Figure 5 (1)- Figure 5 (4) It can be seen that when the receiving system has a frequency disturbance, the frequency coordination control based on variable speed wind turbines and FLC on both sides of the DC is optimal for the system frequency response characteristics. Since the wind turbine responds to the change in DC transmission power and quickly increases the active power, the frequency change at the sending end is smaller than that of FLC control, and the frequency low point is higher. And due to the FLC additional power control, the DC system reduces the active power transmission according to the real-time operating status of the wind turbine, thereby reducing the impact on the sending end system and ensuring the system frequency safety of the power grid containing large-scale wind power sending end.

[0143] In addition, it can be understood by a person skilled in the art that all or part of the processes in the method for implementing the above embodiment can be completed by instructing related hardware through a computer program. The computer program includes program instructions, and the computer program can be stored in a storage medium, which is a computer-readable storage medium. The program instructions are executed by at least one processor in the wind power transmission system to implement the process steps of the embodiment of the above method.

[0144] Therefore, the present application also provides a computer-readable storage medium, which stores a frequency coordination control program based on a variable speed wind turbine set and a normally direct double-sided FLC. When the frequency coordination control program based on a variable speed wind turbine set and a normally direct double-sided FLC is executed by a processor, the various steps of the frequency coordination control method based on a variable speed wind turbine set and a normally direct double-sided FLC as described in the above embodiment are implemented.

[0145] The computer-readable storage medium may be a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk, or an optical disk, etc., which are computer-readable storage media that can store program codes.

[0146] It should be noted that since the storage medium provided in the embodiment of the present application is the storage medium used to implement the method of the embodiment of the present application, based on the method introduced in the embodiment of the present application, the person skilled in the art can understand the specific structure and deformation of the storage medium, so it is not repeated here. All storage media used in the method of the embodiment of the present application belong to the scope of protection of this application.

[0147] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0148] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0149] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0151] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The present application may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0152] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0153] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A frequency coordination control method based on variable speed wind turbines and FLC on both sides of the constant current, characterized in that: Applied to a wind power transmission system, the wind power transmission system includes a normally direct double-sided FLC direct current system as a sending-end asynchronous power grid and a variable speed wind turbine set as a receiving-end asynchronous power grid, and the method includes the following steps: Step S10, when an active power disturbance is detected in the asynchronous interconnected power grid of the wind power transmission system, determining whether the active power disturbance is an active power disturbance of a sending-end system or an active power disturbance of a receiving-end system; Step S21: if it is the active power disturbance of the sending-end system, obtain the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the proportional coefficient of the maximum power tracking curve of the variable-speed wind turbine based on the frequency change of the sending-end power grid and the current angular velocity of the wind turbine, calculate the first additional power of the variable-speed wind turbine based on the proportional coefficient and the current angular velocity of the wind turbine, so as to adjust the power of the variable-speed wind turbine based on the first additional power of the variable-speed wind turbine; and determine the first additional power of FLC based on the current angular velocity of the wind turbine, so as to adjust the power of the normally direct double-sided FLC DC system based on the first additional power of FLC; Step S22: If the active power disturbance is in the receiving-end system, the power value output by the FLC after the receiving-end grid frequency disturbance is determined as the second additional power of the variable-speed wind turbine set, so as to adjust the power of the variable-speed wind turbine set based on the second additional power of the variable-speed wind turbine set; and the difference between the output power of the wind turbine set after releasing the frequency regulation standby and the current FLC output power is used as the second additional power of the FLC, so as to adjust the power of the normally direct double-sided FLC DC system based on the second additional power of the FLC.

2. The method according to claim 1, characterized in that The calculation formula of the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine set is: ； Among them, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current fan angular velocity, Δf r is the frequency change of the power grid at the sending end, k opt is the scale factor of the initial maximum power tracking curve, is the initial angular velocity of the wind turbine; is the cutting angular velocity, is the angular velocity when entering the constant speed region, for The upper limit of the amplitude; P max is the upper limit of the fan output active power, η is the speed adjustment coefficient, , is the angular velocity increment, is the system synchronization angular velocity increment.

3. The method according to claim 2, characterized in that The calculation formula of the first additional power of the variable speed wind turbine set is: ； Where ΔP w1 is the first additional power of the variable speed wind turbine, k' opt is the proportional coefficient of the maximum power tracking curve of the variable speed wind turbine, is the current angular velocity of the fan, and P0 is the initial power of the fan.

4. The method according to claim 3, characterized in that The calculation formula of the FLC first additional power is: ； Where ΔP add is the first additional power of FLC, k p , k i is the PI parameter, is the current fan angular velocity, is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

5. The method according to claim 1, characterized in that After step S21, the method further includes: Collect current fan speed; Calculating a current maximum wind energy utilization coefficient based on the current wind turbine speed and the first additional power of the variable speed wind turbine set, and calculating a first pitch angle according to the current maximum wind energy utilization coefficient; and calculating a second pitch angle based on the current wind turbine speed; Determining a positive or negative value of a first additional power of the variable speed wind turbine generator set; When the first additional power of the variable speed wind turbine generator set is a positive value, adjusting the pitch angle of the variable speed wind turbine generator set based on the larger value of the first pitch angle and the second pitch angle; When the first additional power of the variable speed wind turbine generator set is a negative value, the pitch angle of the variable speed wind turbine generator set is adjusted based on a smaller value between the first pitch angle and the second pitch angle.

6. The method according to claim 5, characterized in that The calculation formula of the current maximum wind energy utilization coefficient is: ； The calculation formula of the first pitch angle is: ； Among them, β1 is the first pitch angle, is the air density, R is the fan blade radius, v is the wind speed, ΔP w1 is the first additional power of the variable speed wind turbine, and P0 is the initial power of the wind turbine.

7. The method according to claim 5, characterized in that The calculation formula of the second pitch angle is: ； Where β2 is the second pitch angle, k p , k i is the PI parameter, is the current fan angular velocity, is the initial angular velocity of the wind turbine, and t is the control action time after the power disturbance occurs.

8. The method according to any one of claims 1 to 7, characterized in that Before the step of determining the FLC first additional power based on the current wind turbine angular velocity to adjust the power of the normally direct double-side FLC direct current system based on the FLC first additional power, the step further includes: Determining whether the first additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval; If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC first additional power; Otherwise, return to the step of determining whether the first additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

9. The method according to any one of claims 1 to 7, characterized in that: Before the step of using the difference between the output power of the wind turbine after releasing the frequency regulation standby and the current FLC output power as the FLC second additional power to adjust the power of the normally direct double-side FLC DC system based on the FLC second additional power, the step further includes: Determining whether the second additional power of the variable speed wind turbine set is within a preset wind turbine output power limit interval; If not, executing the step of adjusting the power of the normally direct double-side FLC direct current system based on the FLC second additional power; Otherwise, return to the step of determining whether the second additional power of the variable-speed wind turbine set is within the preset wind turbine output power limit interval.

10. A wind power transmission system, characterized in that: The wind power transmission system comprises: a memory, a processor and a frequency coordination control program based on variable speed wind turbines and FLC on both sides of the direct current stored in the memory and executable on the processor. When the frequency coordination control program based on variable speed wind turbines and FLC on both sides of the direct current is executed by the processor, the steps of the frequency coordination control method based on variable speed wind turbines and FLC on both sides of the direct current are implemented as described in any one of claims 1 to 9.

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