Control method and device for connecting a double-fed wind turbine to a weak power grid

Abstract

A control method and device for connecting a doubly-fed wind turbine to a weak power grid, the method comprising: adjusting the active power setting value of a wind turbine set in a preset dual-machine system model within an active power adjustment range, determining the maximum active setting value when the grid connection point voltage reaches a low voltage crossing threshold; keeping the maximum active setting value unchanged, adjusting the reactive setting value within a reactive power adjustment range, determining the maximum reactive setting value when the grid connection point voltage reaches a high voltage crossing threshold; setting the active setting value and the reactive setting value to zero, adjusting the active setting value and the reactive setting value according to the maximum active setting value, the maximum reactive setting value and the preset time length, collecting active power and reactive power, determining an online impedance estimation value, obtaining a relationship table of active power and reactive power, and using the relationship table to connect the doubly-fed wind turbine to a weak power grid. The present invention realizes the smooth start-up of the doubly-fed wind turbine under a weak power grid, and avoids the unit entering a low voltage crossing state due to a grid voltage drop when the active power is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of weak power grids, and in particular to a control method and device for connecting a doubly-fed wind turbine to a weak power grid. Background Art

[0002] As the scale of power systems increases and their structures become increasingly complex, the large-scale access of new energy power generation equipment has led to the introduction of new equipment such as power electronics, resulting in a series of new, large-scale, and high-frequency electromagnetic transient problems, such as overvoltage, broadband oscillation, bidirectional power flow, harmonic pollution, etc. These problems will cause drastic changes in system state parameters. Therefore, electromagnetic transient simulation has important practical significance for the current transient analysis of power systems.

[0003] For electromagnetic transient simulation involving large-scale renewable energy, it often takes a long time to adjust the system operation mode due to limitations in computing resources. Especially under weak grid conditions, small active power adjustments often lead to drastic voltage fluctuations, which would consume huge manpower and time if adjusted manually. Summary of the invention

[0004] In view of the problems existing in the prior art, the main purpose of the embodiments of the present invention is to provide a control method and device for connecting a doubly fed wind turbine to a weak power grid, so as to achieve the goal of quickly increasing the output power of the doubly fed wind turbine set while reducing the fluctuation of the grid voltage and preventing the set from entering a voltage ride-through state due to excessively low voltage.

[0005] In order to achieve the above object, an embodiment of the present invention provides a control method for connecting a doubly-fed wind turbine to a weak power grid, the method comprising:

[0006] Within the preset active power adjustment range, the active power setting value of the wind turbine in the preset dual-machine system model is adjusted to determine the maximum active power setting value corresponding to when the grid connection point voltage reaches the preset low voltage crossing threshold;

[0007] The active power setting value of the wind turbine generator set is kept at the maximum active power setting value, and within the preset reactive power adjustment range, the reactive power setting value of the wind turbine generator set in the dual-machine system model is adjusted to determine the maximum reactive power setting value corresponding to when the grid connection point voltage reaches the preset high voltage crossing threshold;

[0008] The active power setting value and reactive power setting value of the wind turbine set are set to zero, and the active power setting value and reactive power setting value of the wind turbine set are adjusted according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and the active power and reactive power output by the wind turbine set are collected;

[0009] Determine the online impedance estimation value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set;

[0010] According to the online impedance estimation value, the relationship table between active power and reactive power is determined, so as to use the relationship table to connect the doubly-fed wind turbine to the weak power grid.

[0011] Optionally, in one embodiment of the present invention, the active power setting value and reactive power setting value of the wind turbine generator set are set to zero, the active power setting value and reactive power setting value of the wind turbine generator set are adjusted according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and the active power and reactive power output by the wind turbine generator set are collected, including:

[0012] The active power setting value and reactive power setting value of the wind turbine generator set in the dual-machine system model are set to zero, and the active power command slope and reactive power command slope are determined according to the maximum active power setting value, the maximum reactive power setting value and the preset time length;

[0013] Adjust the active power setting value and reactive power setting value of the wind turbine set. When the active power setting value reaches half of the maximum active power setting value, collect the active power, reactive power and grid connection point voltage value output by the wind turbine set.

[0014] Optionally, in an embodiment of the present invention, determining the online impedance estimation value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set includes:

[0015] According to the active power, reactive power and grid connection point voltage value output by the wind turbine, the active power time series, reactive power time series and grid connection point voltage time series are obtained;

[0016] According to the active power time series, reactive power time series and grid connection point voltage time series, the impedance time series is obtained;

[0017] According to the impedance time series, the online impedance estimation value of the wind turbine is determined.

[0018] Optionally, in an embodiment of the present invention, determining the relationship table between active power and reactive power according to the online impedance estimation value includes:

[0019] According to the voltage value at the grid connection point, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model and the online impedance estimation value, the functional relationship between active power and reactive power is determined, and the functional relationship is used as a relationship table.

[0020] An embodiment of the present invention further provides a control device for connecting a doubly-fed wind turbine to a weak power grid, the device comprising:

[0021] An active power setting value module is used to adjust the active power setting value of the wind turbine in the preset dual-machine system model within a preset active power adjustment range, and determine the maximum active power setting value corresponding to when the grid connection point voltage reaches a preset low voltage crossing threshold;

[0022] The reactive power setting value module is used to keep the active power setting value of the wind turbine set unchanged at the maximum active power setting value, adjust the reactive power setting value of the wind turbine set in the dual-machine system model within the preset reactive power adjustment range, and determine the maximum reactive power setting value corresponding to when the grid connection point voltage reaches the preset high voltage crossing threshold;

[0023] A power acquisition module is used to set the active power setting value and reactive power setting value of the wind turbine set to zero, adjust the active power setting value and reactive power setting value of the wind turbine set according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and collect the active power and reactive power output by the wind turbine set;

[0024] An online impedance module is used to determine an estimated online impedance value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set;

[0025] The relationship table module is used to determine the relationship table between active power and reactive power according to the online impedance estimation value, so as to use the relationship table to connect the doubly fed wind turbine to the weak power grid.

[0026] Optionally, in one embodiment of the present invention, the power collection module includes:

[0027] The command slope unit is used to set the active power setting value and reactive power setting value of the wind turbine in the dual-machine system model to zero, and determine the active power command slope and reactive power command slope according to the maximum active power setting value, the maximum reactive power setting value and the preset time length;

[0028] The power collection unit is used to adjust the active power setting value and reactive power setting value of the wind turbine set. When the active power setting value reaches half of the maximum active power setting value, the active power, reactive power and grid connection point voltage value output by the wind turbine set are collected.

[0029] Optionally, in one embodiment of the present invention, the online impedance module includes:

[0030] The time series unit is used to obtain the active power time series, reactive power time series and grid connection point voltage time series according to the active power, reactive power and grid connection point voltage values ​​output by the wind turbine generator set;

[0031] An impedance sequence unit is used to obtain an impedance time series according to an active power time series, a reactive power time series and a grid connection point voltage time series;

[0032] The online impedance unit is used to determine the online impedance estimation value of the wind turbine according to the impedance time series.

[0033] Optionally, in one embodiment of the present invention, the relationship table module is also used to determine the functional relationship between active power and reactive power based on the grid connection point voltage value, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model, and the online impedance estimation value, and use the functional relationship as a relationship table.

[0034] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the above method is implemented when the processor executes the program.

[0035] The present invention also provides a computer-readable storage medium, which stores a computer program for executing the above method by a computer.

[0036] The present invention also provides a computer program product, comprising a computer program / instruction, which implements the steps of the above method when the computer program / instruction is executed by a processor.

[0037] The present invention determines the relationship table between active power and reactive power through online impedance estimation and power control, and uses the relationship table to connect the doubly fed wind turbine to a weak power grid, thereby achieving rapid improvement in the output power of the doubly fed wind turbine set while reducing the fluctuation of the power grid voltage, ensuring smooth startup of the doubly fed wind turbine under the weak power grid, and avoiding the unit entering a low voltage ride-through state due to a drop in the power grid voltage when the active power is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a flow chart of a control method for connecting a doubly-fed wind turbine to a weak power grid according to an embodiment of the present invention;

[0040] Figure 2 A flow chart for collecting active power and reactive power output by the wind turbine generator set in an embodiment of the present invention;

[0041] Figure 3 A flow chart of determining an online impedance estimation value in an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the structure of a dual-machine system model in an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of the functional relationship between active power and reactive power in an embodiment of the present invention;

[0044] Figure 6 A schematic diagram of a wind turbine generator system in which a reactive power setting value feedforward module is added in an embodiment of the present invention;

[0045] Figure 7A-7C A schematic diagram of simulation of the operation of a wind turbine generator system according to an embodiment of the present invention;

[0046] Figure 8 This is a structural schematic diagram of a control device for connecting a doubly-fed wind turbine to a weak power grid according to an embodiment of the present invention;

[0047] Fig. 9 This is a schematic diagram of the structure of a power collection module in an embodiment of the present invention;

[0048] Fig.10 It is a structural schematic diagram of an online impedance module in an embodiment of the present invention;

[0049] Fig.11 The figure is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The embodiment of the present invention provides a control method and device for connecting a doubly-fed wind turbine to a weak power grid.

[0051] 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.

[0052] like Figure 1 The flowchart of the control method for connecting a doubly-fed wind turbine to a weak power grid is shown. The execution subject of the control method for connecting a doubly-fed wind turbine to a weak power grid provided by the embodiment of the present invention includes but is not limited to a computer. The present invention determines the relationship table between active power and reactive power through online impedance estimation and power control, and uses the relationship table to connect the doubly-fed wind turbine to a weak power grid, thereby achieving rapid increase in the output power of the doubly-fed wind turbine set while reducing the fluctuation of the grid voltage, ensuring the smooth start-up of the doubly-fed wind turbine under the weak power grid, and avoiding the grid voltage drop when increasing the active power, causing the unit to enter a low voltage ride-through state. The method shown in the figure includes:

[0053] Step S1, within a preset active power adjustment range, adjusting the active power setting value of the wind turbine in the preset dual-machine system model, and determining the maximum active power setting value corresponding to when the grid connection point voltage reaches a preset low voltage crossing threshold;

[0054] Step S2, maintaining the active power setting value of the wind turbine set at the maximum active power setting value unchanged, adjusting the reactive power setting value of the wind turbine set in the dual-machine system model within a preset reactive power adjustment range, and determining the maximum reactive power setting value corresponding to when the grid connection point voltage reaches a preset high voltage crossing threshold;

[0055] Step S3, setting the active power setting value and reactive power setting value of the wind turbine set to zero, adjusting the active power setting value and reactive power setting value of the wind turbine set according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and collecting the active power and reactive power output by the wind turbine set;

[0056] Step S4, determining an online impedance estimation value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set;

[0057] Step S5, determining a relationship table between active power and reactive power according to the online impedance estimation value, so as to use the relationship table to connect the doubly-fed wind turbine to the weak power grid.

[0058] In this embodiment, the equivalent impedance of the system outside the grid connection point is estimated online by sampling and calculating the real-time operation data. The equivalent impedance estimated online is substituted as a parameter into the preset dual-machine system mathematical model, and then the active and reactive power of the grid connection point collected in real time is substituted into the model, and the reactive compensation amount can be calculated to ensure that the voltage of the grid connection point remains unchanged.

[0059] Among them, the preset dual-machine system model is as follows Figure 4 As shown in the figure, the dual-machine system model is shown, where δ is the phase angle of the power supply voltage phasor and E is the amplitude of the system voltage phasor. It is worth noting that in the actual application of wind turbines, there is no need to consider the dual-machine system model, nor to measure or calculate δ.

[0060] Furthermore, the preset dual-machine system model is used to perform online impedance estimation, and the following formula can be directly obtained from the dual-machine system model:

[0061]

[0062] Q 2 X 2 -2U 2 XQ+P 2 X 2 +U 4 -U 2 E 2 =0 (2)

[0063]

[0064] Assuming E=1, considering the actual situation X>0, we have:

[0065]

[0066] Among them, when the unit is in the grid-connected state and the active output is 0, the wind turbine active setting value P set Gradually increase until the grid voltage U≤U min or P set ≥P max That is, within the preset active power adjustment range, adjust the active power setting value of the wind turbine in the preset dual-machine system model, and record the active power setting value at this time as P top , that is, the maximum active setting value corresponding to the time when the grid voltage reaches the preset low voltage crossing threshold. min is a set threshold value, which should be greater than the low voltage ride-through threshold of the unit to ensure that the unit does not fail through the fault during the online impedance estimation period; P max It is the maximum value of the active output of the wind turbine.

[0067] Furthermore, keep P set =P top The wind turbine reactive power setting value Q set Gradually increase (generating inductive reactive power) until U ≥ U max or Q set ≥Q max That is, keep the active power setting value of the wind turbine set at the maximum active power setting value unchanged, adjust the reactive power setting value of the wind turbine set in the dual-machine system model within the preset reactive power adjustment range, and record the Q at this time. set , that is, the maximum reactive power setting value corresponding to the grid voltage reaching the preset high voltage crossing threshold. max is a set value, which should be less than the high voltage ride-through threshold of the unit; Q max It is the maximum value of reactive power output of wind turbine.

[0068] As an embodiment of the present invention, Figure 2 As shown, the active power setting value and reactive power setting value of the wind turbine set are set to zero, and the active power setting value and reactive power setting value of the wind turbine set are adjusted according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and the active power and reactive power output by the wind turbine set are collected, including:

[0069] Step S31, setting the active power setting value and reactive power setting value of the wind turbine generator set in the dual-machine system model to zero, and determining the active power command slope and reactive power command slope according to the maximum active power setting value, the maximum reactive power setting value and the preset time length;

[0070] Step S32, adjusting the active setting value and reactive setting value of the wind turbine generator set, when the active setting value reaches half of the maximum active setting value, collecting the active power, reactive power and grid connection point voltage value output by the wind turbine generator set.

[0071] In this embodiment, if Figure 3 As shown, according to the active power and reactive power output by the wind turbine generator set, determining the online impedance estimation value of the wind turbine generator set includes:

[0072] Step S41, obtaining an active power time series, a reactive power time series and a grid connection point voltage time series according to the active power, reactive power and grid connection point voltage values ​​output by the wind turbine generator set;

[0073] Step S42, obtaining an impedance time series according to the active power time series, the reactive power time series and the grid connection point voltage time series;

[0074] Step S43: determining an online impedance estimation value of the wind turbine generator system according to the impedance time series.

[0075] Among them, the wind turbine active and reactive power setting values ​​P set With Q set Set to 0, the wind turbine output power is 0. Set the preset time length t grow , let the active and reactive setting values ​​of the wind turbine set be respectively based on the slope P top / t grow , Q top / t grow Increase. When P set ≥0.5P top When the active power P, reactive power Q and grid-connected point voltage U of the unit output are collected, the time series (P(t), Q(t), U(t)) are obtained, namely, the active power time series, reactive power time series and grid-connected point voltage time series.

[0076] Furthermore, the collected P, Q, and U are substituted into formula (4) to obtain the sequence X. The sequence X is sorted, and the X samples between the quantiles Q1 to Q3 are selected using the quartile method, denoted as X Q1-Q3 Specifically, quartiles, also known as quartiles, refer to the values ​​at three dividing points when all values ​​are arranged from small to large and divided into four equal parts in statistics. Due to measurement errors, selecting values ​​between Q1-Q3 can improve the accuracy and stability of the values.

[0077] Furthermore, calculate X Q1-Q3 The mean of the samples is used as an online estimate of X That is, the online impedance estimation value of the wind turbine.

[0078] After obtaining the estimated value of the online impedance, the reactive power compensation calculation is performed. Specifically, the reactive power compensation is calculated using Figure 4 The model shown and the phase angle of the power supply voltage phasor and the amplitude of the system voltage phasor specifically involve formula (1) and the following formula:

[0079]

[0080] Let U=E=1, then:

[0081]

[0082] Considering the actual situation, Q<1pu, we have:

[0083]

[0084] In this embodiment, according to Figure 4 The dual-machine system module shown uses the online impedance estimation value to determine the relationship table between active power and reactive power, including: determining the functional relationship between active power and reactive power based on the grid connection point voltage value, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model and the online impedance estimation value, and using the functional relationship as a relationship table.

[0085] Among them, the online estimated value is the system side impedance Substituting into equations (5) and (7), the relationship between P and Q is as follows: Figure 5 shown.

[0086] Furthermore, the functional relationship of PQ is stored in the form of a one-dimensional table as a feedforward module for the reactive power setting value of the wind turbine. set , that is, when the active power is set ,like Figure 6 shown.

[0087] In a specific embodiment of the present invention, the operation of the wind turbine is simulated in three scenarios, which are described in detail as follows:

[0088] Scenario 1: The active power command increases to 1.0 (pu) according to the slope, and the reactive power command is 0;

[0089] Scenario 2: The active power command increases to 1.0 (pu) according to the slope, and the reactive power command jumps to 0.2 (pu);

[0090] Scenario 3: The active power command is increased to 1.0 (pu) according to the slope, and the reactive power command is increased by the table lookup method as described in the present invention.

[0091] The slope can be set arbitrarily.

[0092] In this embodiment, if Figure 7A-7CAs shown, scenario 1 finally leads to too low voltage at the grid connection point, resulting in low voltage ride-through; in scenario 2, the jump-like increase in reactive power causes a sudden change in the voltage at the grid connection point, which is likely to cause high voltage ride-through or other faults; scenario 3: the present invention can make the grid connection point voltage transition smoothly and basically maintain it at around 1.0 (pu), minimizing the impact on equipment and the power grid.

[0093] The present invention determines the relationship table between active power and reactive power through online impedance estimation and power control, and uses the relationship table to connect the doubly fed wind turbine to a weak power grid, thereby achieving rapid improvement in the output power of the doubly fed wind turbine set while reducing the fluctuation of the power grid voltage, ensuring smooth startup of the doubly fed wind turbine under the weak power grid, and avoiding the unit entering a low voltage ride-through state due to a drop in the power grid voltage when the active power is increased.

[0094] like Figure 8 The figure shows a schematic diagram of the structure of a control device for connecting a doubly-fed wind turbine to a weak power grid according to an embodiment of the present invention. The device shown in the figure includes:

[0095] The active power setting value module 10 is used to adjust the active power setting value of the wind turbine in the preset dual-machine system model within the preset active power adjustment range, and determine the maximum active power setting value corresponding to when the grid connection point voltage reaches the preset low voltage crossing threshold;

[0096] The reactive power setting value module 20 is used to keep the active power setting value of the wind turbine generator set unchanged at the maximum active power setting value, adjust the reactive power setting value of the wind turbine generator set in the dual-machine system model within a preset reactive power adjustment range, and determine the maximum reactive power setting value corresponding to when the grid connection point voltage reaches a preset high voltage crossing threshold;

[0097] The power collection module 30 is used to set the active power setting value and reactive power setting value of the wind turbine set to zero, adjust the active power setting value and reactive power setting value of the wind turbine set according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and collect the active power and reactive power output by the wind turbine set;

[0098] An online impedance module 40 is used to determine an online impedance estimation value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set;

[0099] The relationship table module 50 is used to determine the relationship table between active power and reactive power according to the online impedance estimation value, so as to use the relationship table to connect the doubly-fed wind turbine to the weak power grid.

[0100] As an embodiment of the present invention, Fig. 9 As shown, the power collection module 30 includes:

[0101] The command slope unit 31 is used to set the active setting value and reactive setting value of the wind turbine in the dual-machine system model to zero, and determine the active command slope and reactive command slope according to the maximum active setting value, the maximum reactive setting value and the preset time length;

[0102] The power collection unit 32 is used to adjust the active setting value and reactive setting value of the wind turbine generator set. When the active setting value reaches half of the maximum active setting value, the active power, reactive power and grid connection point voltage value output by the wind turbine generator set are collected.

[0103] In this embodiment, if Fig.10 As shown, the online impedance module 40 includes:

[0104] The time series unit 41 is used to obtain the active power time series, the reactive power time series and the grid connection point voltage time series according to the active power, reactive power and grid connection point voltage values ​​output by the wind turbine generator set;

[0105] The impedance sequence unit 42 is used to obtain an impedance time series according to the active power time series, the reactive power time series and the grid connection point voltage time series;

[0106] The online impedance unit 43 is used to determine the online impedance estimation value of the wind turbine generator system according to the impedance time series.

[0107] In this embodiment, the relationship table module 50 is also used to determine the functional relationship between active power and reactive power based on the grid connection point voltage value, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model, and the online impedance estimation value, and use the functional relationship as a relationship table.

[0108] The present invention determines the relationship table between active power and reactive power through online impedance estimation and power control, and uses the relationship table to connect the doubly fed wind turbine to a weak power grid, thereby achieving rapid improvement in the output power of the doubly fed wind turbine set while reducing the fluctuation of the power grid voltage, ensuring smooth startup of the doubly fed wind turbine under the weak power grid, and avoiding the unit entering a low voltage ride-through state due to a drop in the power grid voltage when the active power is increased.

[0109] Based on the same application concept as the control method for connecting a doubly-fed wind turbine to a weak power grid, the present invention also provides the control device for connecting a doubly-fed wind turbine to a weak power grid. Since the principle of solving the problem by the control device for connecting a doubly-fed wind turbine to a weak power grid is similar to that of the control method for connecting a doubly-fed wind turbine to a weak power grid, the implementation of the control device for connecting a doubly-fed wind turbine to a weak power grid can refer to the implementation of the control method for connecting a doubly-fed wind turbine to a weak power grid, and the repeated parts will not be repeated.

[0110] The present invention determines the relationship table between active power and reactive power through online impedance estimation and power control, and uses the relationship table to connect the doubly fed wind turbine to a weak power grid, thereby achieving rapid improvement in the output power of the doubly fed wind turbine set while reducing the fluctuation of the power grid voltage, ensuring smooth startup of the doubly fed wind turbine under the weak power grid, and avoiding the unit entering a low voltage ride-through state due to a drop in the power grid voltage when the active power is increased.

[0111] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the above method is implemented when the processor executes the program.

[0112] The present invention also provides a computer program product, comprising a computer program / instruction, which implements the steps of the above method when the computer program / instruction is executed by a processor.

[0113] The present invention also provides a computer-readable storage medium, which stores a computer program for executing the above method by a computer.

[0114] like Fig.11 As shown, the electronic device 600 may further include: a communication module 110, an input unit 120, an audio processor 130, a display 160, and a power supply 170. It is worth noting that the electronic device 600 does not necessarily have to include Fig.11 In addition, the electronic device 600 may also include Fig.11 For components not shown, reference may be made to the prior art.

[0115] like Fig.11 As shown, the central processor 100 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor devices and / or logic devices. The central processor 100 receives inputs and controls the operations of various components of the electronic device 600.

[0116] The memory 140 may be, for example, one or more of a cache, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory or other suitable devices. The above-mentioned information related to the failure may be stored, and a program for executing the relevant information may also be stored. The CPU 100 may execute the program stored in the memory 140 to implement information storage or processing.

[0117] The input unit 120 provides input to the CPU 100. The input unit 120 is, for example, a key or a touch input device. The power supply 170 is used to provide power to the electronic device 600. The display 160 is used to display display objects such as images and text. The display may be, for example, an LCD display, but is not limited thereto.

[0118] The memory 140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), a SIM card, etc. It may also be a memory that saves information even when the power is off, can be selectively erased, and is provided with more data, examples of which are sometimes referred to as EPROMs, etc. The memory 140 may also be some other type of device. The memory 140 includes a buffer memory 141 (sometimes referred to as a buffer). The memory 140 may include an application / function storage unit 142, which is used to store application programs and function programs or processes for executing the operation of the electronic device 600 through the central processor 100.

[0119] The memory 140 may also include a data storage unit 143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 144 of the memory 140 may include various drivers for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0120] The communication module 110 is a transmitter / receiver 110 that transmits and receives signals via an antenna 111. The communication module (transmitter / receiver) 110 is coupled to the central processor 100 to provide input signals and receive output signals, which may be the same as the case of a conventional mobile communication terminal.

[0121] Based on different communication technologies, multiple communication modules 110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module and / or a wireless LAN module. The communication module (transmitter / receiver) 110 is also coupled to a speaker 131 and a microphone 132 via an audio processor 130 to provide an audio output via the speaker 131 and receive an audio input from the microphone 132, thereby realizing a common telecommunication function. The audio processor 130 may include any suitable buffer, decoder, amplifier, etc. In addition, the audio processor 130 is also coupled to the central processor 100, so that the sound can be recorded on the local machine through the microphone 132, and the sound stored on the local machine can be played through the speaker 131.

[0122] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention 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 code.

[0123] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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.

[0124] 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 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0125] 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.

[0126] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A control method for connecting a doubly-fed wind turbine to a weak power grid, characterized in that: The method comprises: Within the preset active power adjustment range, the active power setting value of the wind turbine in the preset dual-machine system model is adjusted to determine the maximum active power setting value corresponding to when the grid connection point voltage reaches the preset low voltage crossing threshold; Maintaining the active power setting value of the wind turbine generator set at the maximum active power setting value, adjusting the reactive power setting value of the wind turbine generator set in the dual-machine system model within a preset reactive power adjustment range, and determining the maximum reactive power setting value corresponding to when the grid connection point voltage reaches a preset high voltage crossing threshold; The active power setting value and reactive power setting value of the wind turbine generator set in the dual-machine system model are set to zero, and the active power command slope and reactive power command slope are determined according to the maximum active power setting value, the maximum reactive power setting value and the preset time length; Adjusting the active power setting value and reactive power setting value of the wind turbine generator set, and when the active power setting value reaches half of the maximum active power setting value, collecting the active power, reactive power and grid connection point voltage value output by the wind turbine generator set; According to the active power, reactive power and grid connection point voltage value output by the wind turbine generator set, an active power time series, a reactive power time series and a grid connection point voltage time series are obtained; Obtaining an impedance time series according to the active power time series, the reactive power time series and the grid connection point voltage time series; Determining an online impedance estimation value of the wind turbine generator system according to the impedance time series; According to the grid connection point voltage value, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model and the online impedance estimation value, the functional relationship between active power and reactive power is determined, and the functional relationship is used as a relationship table to use the relationship table to connect the doubly fed wind turbine to the weak power grid.

2. A control device for connecting a doubly-fed wind turbine to a weak power grid, characterized in that: The device comprises: An active power setting value module is used to adjust the active power setting value of the wind turbine in the preset dual-machine system model within a preset active power adjustment range, and determine the maximum active power setting value corresponding to when the grid connection point voltage reaches a preset low voltage crossing threshold; A reactive power setting value module is used to keep the active power setting value of the wind turbine generator set unchanged at the maximum active power setting value, adjust the reactive power setting value of the wind turbine generator set in the dual-machine system model within a preset reactive power adjustment range, and determine the maximum reactive power setting value corresponding to when the grid connection point voltage reaches a preset high voltage crossing threshold; A power collection module, used to set the active power setting value and the reactive power setting value of the wind turbine set to zero, adjust the active power setting value and the reactive power setting value of the wind turbine set according to the maximum active power setting value, the maximum reactive power setting value and the preset time length, and collect the active power and reactive power output by the wind turbine set; An online impedance module, used to determine an online impedance estimation value of the wind turbine generator set according to the active power and reactive power output by the wind turbine generator set; A relationship table module, used to determine a relationship table between active power and reactive power according to the online impedance estimation value, so as to use the relationship table to connect the doubly-fed wind turbine to a weak power grid; The power collection module comprises: A command slope unit, used to set the active power setting value and reactive power setting value of the wind turbine generator set in the dual-machine system model to zero, and determine the active power command slope and reactive power command slope according to the maximum active power setting value, the maximum reactive power setting value and a preset time length; A power collection unit, used to adjust the active power setting value and reactive power setting value of the wind turbine generator set, and when the active power setting value reaches half of the maximum active power setting value, collect the active power, reactive power and grid connection point voltage value output by the wind turbine generator set; The online impedance module comprises: A time series unit, used to obtain an active power time series, a reactive power time series and a grid connection point voltage time series according to the active power, reactive power and grid connection point voltage values ​​output by the wind turbine generator set; An impedance sequence unit, used to obtain an impedance time series according to the active power time series, the reactive power time series and the grid connection point voltage time series; An online impedance unit, used to determine an online impedance estimation value of the wind turbine generator set according to the impedance time series; The relationship table module is also used to determine the functional relationship between active power and reactive power based on the grid connection point voltage value, the system voltage phasor amplitude in the dual-machine system model, the power supply voltage phasor phase angle in the dual-machine system model and the online impedance estimation value, and use the functional relationship as the relationship table.

3. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method of claim 1 is implemented.

4. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for causing a computer to execute the method of claim 1.

5. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to claim 1 are implemented.

Images