Virtual impedance and virtual capacitance algorithm-based reactive power equalization method for grid-forming type doubly-fed wind turbine generator

Abstract

The invention discloses a virtual impedance and virtual capacitance algorithm-based reactive power equalization method for a grid-forming doubly-fed wind turbine generator, and the method comprises the steps: 1, collecting the stator and rotor current and voltage of the doubly-fed wind turbine generator, and calculating the dq-axis components of the stator and rotor current and voltage through coordinate transformation; 2, calculating the value range of virtual inductive reactance Xv by using the power equalization error upper limit QerrMAX and the virtual impedance output voltage lower limit Exmin of the doubly-fed wind turbine generator; 3, calculating the value range of the virtual capacitor Cv by using the output voltage lower limit Ecmin, the output voltage upper limit Ecmax and the reactive output upper limit Qmax of the virtual capacitor; 4, calculating stator d-axis and q-axis voltage feed-forward instructions udvivc and uqvivc according to a virtual impedance and virtual capacitance algorithm; and 5, calculating by using the stator voltage loop and the rotor current loop to obtain a rotor voltage instruction, and modulating to generate a rotor side converter driving signal. According to the invention, the reactive power equalization error of the grid-forming type doubly-fed wind turbine generator can be reduced, and the reactive power equalization precision of the grid-forming type doubly-fed wind turbine generator can be improved.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power generation, and in particular to a reactive power balancing method for a grid-connected doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm in a microgrid. Background Art

[0002] The penetration rate of renewable energy is climbing year by year. When wind power penetration reaches 100%, doubly-fed wind turbines will be able to break free from their reliance on traditional power grids and enable the construction of a renewable energy network. At that point, multiple doubly-fed wind turbines will collaboratively form a microgrid. Because the output impedance of each turbine and the impedance of the lines to which it is connected are primarily inductive, and the angular frequency of the output voltages of multiple turbines is the same in steady state, the load active power can be automatically evenly distributed according to the droop factor. However, due to the diverse geographical locations of the turbines in the microgrid and the varying distances to loads and users, the line impedance cannot be perfectly matched to the rated capacity, making it difficult to achieve evenly distributed reactive loads using traditional droop control. This limitation can cause overload of a particular doubly-fed wind turbine in the microgrid, threatening the stable operation of the entire system.

[0003] Research on reactive power sharing for grid-connected doubly-fed wind turbines in microgrids is insufficient, and most current power sharing strategies focus primarily on microgrid inverters. Existing solutions to reactive power sharing include virtual impedance algorithms, virtual capacitor algorithms, and variable droop coefficient schemes. However, each of these solutions has its limitations. For example, while the virtual impedance algorithm can achieve significant power sharing, it also reduces the voltage control accuracy of the system at the point of common coupling. The virtual capacitor algorithm can improve power sharing accuracy while maintaining voltage control accuracy, but its improvement still lags behind that of the virtual impedance algorithm. The variable droop coefficient scheme improves power sharing accuracy at the expense of system stability, limiting its practical application. Therefore, improving the reactive power sharing capability of grid-connected doubly-fed wind turbines in microgrids remains a core challenge, requiring further research and breakthroughs. Summary of the Invention

[0004] In order to solve the problem that, in a microgrid environment, the line impedance between the output end and the load end of each grid-type doubly-fed wind turbine unit is different, and it is difficult for each unit to share the load power according to its own droop coefficient when the reactive load is connected, the present invention proposes a reactive power sharing method for grid-type doubly-fed wind turbine units based on virtual impedance and virtual capacitance algorithms, in order to solve the reactive power sharing problem of grid-type doubly-fed wind turbine units in microgrids, reduce the voltage drop caused by the traditional virtual impedance algorithm when improving the reactive power sharing accuracy, and thus achieve the simultaneous improvement of the reactive power sharing accuracy and voltage control accuracy of the grid-type doubly-fed wind turbine units.

[0005] In order to achieve the above-mentioned object, the present invention adopts the following technical solutions:

[0006] The reactive power balancing method for a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm is characterized in that it is applied to a grid-type doubly-fed wind power generation system composed of a doubly-fed generator and a machine-side converter in a microgrid, and is performed according to the following steps:

[0007] Step 1: Collect the three-phase voltage and three-phase current on the stator and rotor sides and obtain the d-axis DC component u of the stator voltage in the synchronous rotating coordinate system after coordinate transformation. sd , q-axis DC component u sq and the d-axis DC component i of the stator current in the synchronous rotating coordinate system sd , q-axis DC component i sq And the d-axis DC component i of the rotor current in the synchronous rotating coordinate system rd , q-axis DC component i rq ;

[0008] Step 2: According to the upper limit of the power sharing error of the doubly fed wind turbine The virtual impedance output voltage lower limit E xmin , calculate the virtual inductive reactance X v The value range of

[0009] Step 3: Use virtual capacitor to output voltage lower limit E cmin and the output voltage upper limit E cmax And the reactive output upper limit Q of the doubly fed generator max , calculate the virtual capacitance C v The value range of

[0010] Step 4: According to the virtual inductive reactance X v and virtual capacitor C v The value range of the virtual inductive reactance is determined to determine the final value X v0 And the final value of virtual capacitance C v0 ;

[0011] Step 5: Based on the output reactive power Q of the doubly fed generator and the filtered reactive power Q f , calculate the stator d-axis voltage loop command value u in the synchronous rotating coordinate system sdref and q-axis voltage loop command value u sqref ;

[0012] Step 6, based on X v0 and C v0 , use the virtual impedance and virtual capacitance algorithm to calculate the stator d-axis voltage feedforward instruction u d_vivc and q-axis voltage feedforward command u q_vivc ;

[0013] Step 7.sdref with u d_vivc After superposition, the new d-axis stator voltage command u is obtained sdref1 ; At the same time, u sqref and u q_vivc After superposition, the new q-axis stator voltage command u is obtained sqref1 ;

[0014] Step 8: According to u sdref1 With d-axis stator feedback u sd The deviation and u sqref1 With q-axis stator feedback u sq The PI regulator of the stator voltage outer loop is used to calculate the d-axis rotor current command i in the synchronous rotating coordinate system. rdref , q-axis rotor current command i rqref ;

[0015] Step 9: According to i rdref With the d-axis rotor current feedback i rd The deviation and i rqref With the q-axis rotor current feedback i rq The PI regulator of the rotor current inner loop is used to calculate the d-axis rotor voltage command u in the synchronous rotating coordinate system. rdref , q-axis rotor voltage command u rqref ;

[0016] Step 10: D-axis rotor voltage command u rdref , q-axis rotor voltage command u rqref After modulation by the SVPWM link, the rotor-side converter switch control signals S1-S6 are generated to achieve reactive power sharing control of the doubly-fed wind turbine in the microgrid.

[0017] The reactive power balancing method for a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to the present invention is also characterized in that step 2 comprises:

[0018] Step 2.1: Output voltage lower limit E according to virtual impedance xmin The upper limit of the virtual inductive reactance X is calculated using formula (3). vmax :

[0019] (3)

[0020] In formula (3), i represents the number of the doubly fed generator, X li represents the line inductance of the i-th doubly fed generator, X vi The output voltage of the i-th doubly fed generator is E xmin The corresponding virtual inductive reactance, E n Indicates the stator line voltage rating of the doubly fed generator, Vpcc Indicates the line voltage at the common coupling point, n q Indicates the reactive power droop coefficient;

[0021] Step 2.2: According to the upper limit of power sharing error Q errMAX The lower limit of the virtual inductive reactance X is calculated using formula (4). vmin and with X vmax Constructing virtual inductive reactance X v The value range of is:

[0022] (4)

[0023] In formula (4), Q ldMAX Indicates the upper limit of reactive load, Q0 indicates when the rated power of reactive load is Q ldMAX The reactive power output by the first doubly fed generator is Q n Indicates the rated reactive power, Indicates the line inductance of the first doubly-fed generator.

[0024] Furthermore, the step 3 includes:

[0025] Step 3.1: The maximum value of the output voltage of the doubly-fed generator at no-load is limited by the upper limit of the virtual capacitor output voltage E cmax Under the constraint condition, the upper limit of the virtual capacitance C is calculated using formula (5) vmax :

[0026] (5)

[0027] In formula (5), ω n Indicates the rated angular frequency, X v represents virtual inductive reactance;

[0028] Step 3.2: When fully loaded, the output voltage of the doubly-fed generator is not lower than the lower limit of the virtual capacitor output voltage E cmin Under the condition of , use formula (6) to calculate the lower limit of the virtual capacitance C vmin and with C vmax Constructing a virtual capacitor C v The value range of is:

[0029] (6).

[0030] Furthermore, in step 4, the final value X of the virtual inductive reactance is calculated using formula (7): v0 And the final value of virtual capacitance C v0 :

[0031] (7)

[0032] In formula (7), α represents the virtual impedance adjustment coefficient, β represents the virtual capacitance adjustment coefficient, and the values of α and β are between 0 and 1. vmax (X v0 ) and C vmin (X v0 ) means to convert X v0 Assign to X v Then, substitute into formula (5) and formula (6) for calculation.

[0033] Furthermore, in step 6, equation (8) is used to calculate u d_vivc and u q_vivc :

[0034] (8)

[0035] In formula (8), Indicates the stator q-axis voltage loop command value.

[0036] Furthermore, in step 8, formula (9) is used to obtain i rdref and i rqref :

[0037] (9)

[0038] In formula (9), K pv and K iv Respectively represent the proportional coefficient and integral coefficient of the PI regulator of the stator voltage outer loop, represents the Laplace operator.

[0039] Furthermore, in step 9, we use formula (10) to get u rdref and u rqref :

[0040] (10)

[0041] In formula (10), K pi and K ii They are the proportional coefficient and integral coefficient of the PI regulator of the rotor current inner loop respectively.

[0042] The electronic device of the present invention includes a memory and a processor, and is characterized in that the memory is used to store a program that supports the processor to execute the reactive power balancing method of the grid-type doubly fed wind turbine set, and the processor is configured to execute the program stored in the memory.

[0043] The present invention provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium. The computer program is characterized in that when the computer program is run by a processor, the steps of the reactive power balancing method of the grid-type doubly-fed wind turbine are executed.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. This invention proposes a control structure that integrates virtual impedance and virtual capacitance. Compared with traditional solutions, it effectively coordinates the contradiction between the difficulty in simultaneously improving the reactive power sharing accuracy and the voltage control accuracy at the common coupling point, thereby improving the operating performance of doubly fed wind turbines in microgrid scenarios.

[0046] 2. The present invention provides a basis for selecting parameters of virtual impedance and virtual capacitance, and can freely design the parameters of virtual impedance and virtual capacitance according to the desired power sharing accuracy and voltage control accuracy, thereby simplifying the parameter setting steps and effectively reducing the difficulty of applying the method of the present invention in actual engineering practice;

[0047] 3. When calculating the voltage feedforward instructions of the stator d-axis and q-axis using the virtual impedance and virtual capacitance algorithms, each doubly-fed wind turbine only needs to collect the local stator d-axis and q-axis current components to calculate the voltage feedforward instructions without relying on a communication module, thereby reducing control costs and avoiding stability issues caused by communication failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a voltage-current dual closed-loop structure diagram that incorporates virtual impedance and virtual capacitance algorithms in the present invention;

[0049] Figure 2 This is a control structure diagram of a grid-type doubly-fed wind turbine generator system based on the virtual impedance and virtual capacitance algorithm of the present invention. DETAILED DESCRIPTION

[0050] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0051] In this embodiment, a method for reactive power balancing of a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm is applied to a grid-type doubly-fed wind power generation system composed of a doubly-fed generator and a machine-side converter in a microgrid. The method is used to coordinate the contradiction between the reactive power balancing accuracy of the grid-type doubly-fed wind turbine generator system and the simultaneous improvement of the voltage control accuracy in the microgrid, thereby improving the power balancing performance of the grid-type doubly-fed wind power generation system. Specifically, the method is performed in the following steps:

[0052] Step 1: Data collection and coordinate transformation calculation on the stator and rotor sides;

[0053] like Figure 2 As shown, the stator three-phase voltage u of the doubly fed generator is sampled sa 、u sb 、u sc and stator three-phase current i sa 、i sb 、isc , and bring it into the coordinate transformation link shown in formula (1) to obtain the d-axis and q-axis DC components u of the stator voltage in the synchronous rotating coordinate system sd 、u sq And the d-axis and q-axis DC components i of the stator current in the synchronous rotating coordinate system sd 、i sq :

[0054] (1)

[0055] In formula (1), θ s is the stator coordinate transformation angle, x A 、x B 、x C represents the three-phase stator voltage / current of the doubly fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

[0056] Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc , and bring it into the coordinate transformation link shown in formula (2) to obtain the d-axis and q-axis DC components i of the rotor current in the synchronous rotating coordinate system rd 、i rq :

[0057] (2)

[0058] In formula (2), θ r Indicates the rotor electrical angle.

[0059] Step 2: According to the upper limit of the power sharing error Q of the doubly fed wind turbine errMAX The virtual impedance output voltage lower limit E xmin Calculate virtual inductive reactance X v The value range of

[0060] According to the lower limit E of the virtual impedance output voltage xmin The upper limit of the virtual inductive reactance X is calculated using formula (3). vmax :

[0061] (3)

[0062] In formula (3), i represents the number of the doubly fed generator, X li represents the line inductance of the i-th doubly fed generator, X vi The output voltage of the i-th doubly fed generator is E xmin The corresponding virtual inductive reactance, En Indicates the stator line voltage rating of the doubly fed generator, V pcc Indicates the line voltage at the common coupling point, n q Indicates the reactive droop coefficient;

[0063] According to the upper limit of power sharing error Q errMAX The lower limit of the virtual inductive reactance X is calculated using formula (4). vmin and with X vmax Constructing virtual inductive reactance X v The value range of is:

[0064] (4)

[0065] In formula (4), Q ldMAX Indicates the upper limit of reactive load, Q0 indicates when the rated power of reactive load is Q ldMAX The reactive power output by the first doubly fed generator is Q n Indicates the rated reactive power, Indicates the line inductance of the first doubly-fed generator.

[0066] Step 3: Use virtual capacitor to output voltage lower limit E cmin and the output voltage upper limit E cmax And the reactive output upper limit Q of the doubly fed generator max Calculate the virtual capacitance C v The value range of

[0067] According to the no-load condition, the output voltage of the doubly-fed generator has a maximum value, and it is subject to the upper limit of the virtual capacitor output voltage E cmax The upper limit of the virtual capacitance C is calculated using formula (5). vmax :

[0068] (5)

[0069] In formula (5), ω n Indicates the rated angular frequency, X v Indicates virtual inductive reactance.

[0070] According to the virtual impedance at full load, the system will bring a large voltage drop. In order to ensure that the output voltage of the double-fed generator is not lower than the lower limit of the virtual capacitor output voltage E cmin , use formula (6) to calculate the lower limit of the virtual capacitance C vmin and with C vmax Constructing a virtual capacitor C v The value range of is:

[0071] (6)

[0072] Step 4: According to the virtual inductive reactance Xv and virtual capacitor C v The range of values determines the final value of the virtual inductive reactance X v0 And the final value of virtual capacitance C v0 ;

[0073] According to the upper and lower limits of virtual inductive reactance X vmax and X vmin , and the upper and lower limits of the virtual capacitance C vmax and C vmin , use formula (7) to calculate the final value of virtual inductive reactance X v0 And the final value of virtual capacitance C v0 :

[0074] (7)

[0075] In formula (7), α represents the virtual impedance adjustment coefficient, β represents the virtual capacitance adjustment coefficient, and the values of α and β are between 0 and 1. vmax (X v0 ) and C vmin (X v0 ) means to convert X v0 Assign to X v Then, substitute into formula (5) and formula (6) for calculation.

[0076] Step 5: Figure 2 As shown, according to the reactive power Q output by the doubly fed generator and the filtered reactive power Q f , calculate the stator d-axis voltage loop command value u in the synchronous rotating coordinate system sdref and q-axis voltage loop command value u sqref ;

[0077] Use formula (8) to calculate the output reactive power Q of the doubly fed generator and the filtered reactive power Q f :

[0078] (8)

[0079] In formula (8), G f represents the transfer function of the low-pass filter, and G f =ω f / (s + ω f ),ω f is the cutoff frequency of the low-pass filter, s represents the Laplace operator;

[0080] Use formula (9) to calculate the stator d-axis voltage loop command value u sdref and q-axis voltage loop command value u sqref :

[0081] (9)

[0082] In formula (9), U n Indicates the rated value of the stator phase voltage amplitude of the doubly fed generator.

[0083] Step 6: Calculate the stator d-axis and q-axis voltage feedforward instructions u using the virtual impedance and virtual capacitance algorithm d_vivc and u q_vivc ;

[0084] like Figure 1 As shown, the stator d-axis and q-axis voltage feedforward instructions u of the virtual impedance and virtual capacitance algorithm are calculated using formula (10): d_vivc and u q_vivc :

[0085] (10)

[0086] Step 7: Figure 2 As shown, the stator voltage outer loop command value u is converted into sdref and u sqref With the voltage feedforward command u d_vivc and u q_vivc After superposition, the new stator voltage command u is obtained sdref1 and u sqref1 :

[0087] (11)

[0088] Step 8: Figure 2 As shown, calculate the d-axis and q-axis stator voltage instructions u in the synchronous rotating coordinate system sdref1 、u sqref1 Respectively with the d-axis and q-axis stator feedback u sd 、u sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system are obtained using formula (12): rdref 、i rqref :

[0089] (12)

[0090] In formula (12), K pv and K iv They represent the proportional coefficient and integral coefficient of the stator voltage outer loop PI regulator respectively.

[0091] Step 9: Figure 2 As shown, calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rdref 、i rqref Respectively with the d-axis and q-axis rotor current feedback i rd 、irq The deviation is input into the PI regulator of the rotor current inner loop for processing, so that the d-axis and q-axis rotor voltage instructions u in the synchronous rotating coordinate system are obtained using formula (13): rdref 、u rqref :

[0092] (13)

[0093] In formula (13), K pi and K ii They are the proportional coefficient and integral coefficient of the rotor current inner loop PI regulator respectively.

[0094] Step 10: d-axis and q-axis rotor voltage instructions u rdref 、u rqref After modulation by the SVPWM link, the rotor-side converter switch control signals S1-S6 are generated to achieve reactive power sharing control of the doubly-fed wind turbine in the microgrid.

[0095] In this embodiment, an electronic device includes a memory and a processor. The memory is used to store a program that supports the processor to execute the above-mentioned grid-type doubly-fed wind turbine reactive power sharing method. The processor is configured to execute the program stored in the memory.

[0096] In this embodiment, a computer-readable storage medium stores a computer program, which, when executed by a processor, executes the steps of the above-mentioned method for reactive power equalization of grid-type doubly-fed wind turbines.

[0097] Figure 1 This is the voltage and current double closed-loop structure diagram with virtual impedance and virtual capacitance algorithms added. Figure 2 The control structure diagram of the grid-type doubly fed wind turbine based on the virtual impedance and virtual capacitance algorithm is shown in Figure 2. The four PI controllers of the stator voltage and rotor current double closed loop are used to achieve fast zero-static error tracking control of the stator voltage and rotor current. The feedforward voltage command u is superimposed on the stator voltage loop command. d_vivc and u q_vivc It is used to improve the reactive power sharing accuracy and voltage control accuracy of grid-forming doubly-fed wind turbines under microgrids, and improve the operating performance of grid-forming doubly-fed wind turbines under microgrids.

Claims

1. A reactive power sharing method for a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm, characterized in that: It is applied to the grid-type doubly-fed wind power generation system composed of a doubly-fed generator and a machine-side converter under a microgrid, and is carried out in the following steps: Step 1: Collect the three-phase voltage and three-phase current on the stator and rotor sides and obtain the d-axis DC component u of the stator voltage in the synchronous rotating coordinate system after coordinate transformation. sd , q-axis DC component u sq and the d-axis DC component i of the stator current in the synchronous rotating coordinate system sd , q-axis DC component i sq And the d-axis DC component i of the rotor current in the synchronous rotating coordinate system rd , q-axis DC component i rq ; Step 2: According to the upper limit of the power sharing error of the doubly fed wind turbine The virtual impedance output voltage lower limit E xmin , calculate the virtual inductive reactance X v The value range of Step 3: Use virtual capacitor to output voltage lower limit E cmin and the output voltage upper limit E cmax And the reactive output upper limit Q of the doubly fed generator max , calculate the virtual capacitance C v The value range of Step 4: According to the virtual inductive reactance X v and virtual capacitor C v The value range of the virtual inductive reactance is determined to determine the final value X v0 And the final value of virtual capacitance C v0 ; Step 5: Based on the output reactive power Q of the doubly fed generator and the filtered reactive power Q f , calculate the stator d-axis voltage loop command value u in the synchronous rotating coordinate system sdref and q-axis voltage loop command value u sqref ; Step 6, based on X v0 and C v0 , use the virtual impedance and virtual capacitance algorithm to calculate the stator d-axis voltage feedforward instruction u d_vivc and q-axis voltage feedforward command u q_vivc ; Step 7: sdref with u d_vivc After superposition, the new d-axis stator voltage command u is obtained sdref1 ; At the same time, u sqref and u q_vivc After superposition, the new q-axis stator voltage command u is obtained sqref1 ; Step 8: According to u sdref1 With d-axis stator feedback u sd The deviation and u sqref1 With q-axis stator feedback u sq The PI regulator of the stator voltage outer loop is used to calculate the d-axis rotor current command i in the synchronous rotating coordinate system. rdref , q-axis rotor current command i rqref ; Step 9: According to i rdref With the d-axis rotor current feedback i rd The deviation and i rqref With the q-axis rotor current feedback i rq The PI regulator of the rotor current inner loop is used to calculate the d-axis rotor voltage command u in the synchronous rotating coordinate system. rdref , q-axis rotor voltage command u rqref ; Step 10: D-axis rotor voltage command u rdref , q-axis rotor voltage command u rqref After modulation by the SVPWM link, the rotor-side converter switch control signals S1-S6 are generated to achieve reactive power sharing control of the doubly-fed wind turbine in the microgrid.

2. The reactive power sharing method of a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 1, characterized in that: The step 2 includes: Step 2.1: Output voltage lower limit E according to virtual impedance xmin The upper limit of the virtual inductive reactance X is calculated using formula (3). vmax : (3) In formula (3), i represents the number of the doubly fed generator, X li represents the line inductance of the i-th doubly fed generator, X vi The output voltage of the i-th doubly fed generator is E xmin The corresponding virtual inductive reactance, E n Indicates the stator line voltage rating of the doubly fed generator, V pcc Indicates the line voltage at the common coupling point, n q Indicates the reactive droop coefficient; Step 2.2: According to the upper limit of power sharing error Q errMAX The lower limit of the virtual inductive reactance X is calculated using formula (4). vmin and with X vmax Constructing virtual inductive reactance X v The value range of is: (4) In formula (4), Q ldMAX Indicates the upper limit of reactive load, Q0 indicates when the rated power of reactive load is Q ldMAX The reactive power output by the first doubly fed generator is Q n Indicates the rated reactive power, Indicates the line inductance of the first doubly-fed generator.

3. The method for sharing reactive power of a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 2, characterized in that: The step 3 includes: Step 3.1: The maximum value of the output voltage of the doubly-fed generator at no-load is limited by the upper limit of the virtual capacitor output voltage E cmax Under the constraint condition, the upper limit of the virtual capacitance C is calculated using formula (5) vmax : (5) In formula (5), ω n Indicates the rated angular frequency, X v represents virtual inductive reactance; Step 3.2: When fully loaded, the output voltage of the doubly-fed generator is not lower than the lower limit of the virtual capacitor output voltage E cmin Under the condition of , use formula (6) to calculate the lower limit of the virtual capacitance C vmin and with C vmax Constructing a virtual capacitor C v The value range of is: (6)。 4. The method for sharing reactive power of a grid-type doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 3, characterized in that: In step 4, the final value of the virtual inductive reactance X is calculated using formula (7): v0 And the final value of virtual capacitance C v0 : (7) In formula (7), α represents the virtual impedance adjustment coefficient, β represents the virtual capacitance adjustment coefficient, and the values of α and β are between 0 and 1. vmax (X v0 ) and C vmin (X v0 ) means to convert X v0 Assign to X v Then, substitute into formula (5) and formula (6) for calculation.

5. The method for sharing reactive power of a grid-connected doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 4, characterized in that: In step 6, equation (8) is used to calculate u d_vivc and u q_vivc : (8) In formula (8), Indicates the stator q-axis voltage loop command value.

6. The method for sharing reactive power of a grid-connected doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 5, characterized in that: In step 8, formula (9) is used to obtain i rdref and i rqref : (9) In formula (9), K pv and K iv Respectively represent the proportional coefficient and integral coefficient of the PI regulator of the stator voltage outer loop, represents the Laplace operator.

7. The method for sharing reactive power of a grid-connected doubly-fed wind turbine generator system based on a virtual impedance and virtual capacitance algorithm according to claim 6, characterized in that: In step 9, we use formula (10) to get u rdref and u rqref : (10) In formula (10), K pi and K ii They are the proportional coefficient and integral coefficient of the PI regulator of the rotor current inner loop respectively.

8. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the reactive power balancing method for a grid-type doubly-fed wind turbine generator set according to any one of claims 1 to 7, and the processor is configured to execute the program stored in the memory.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the reactive power balancing method for a grid-type doubly-fed wind turbine generator set according to any one of claims 1 to 7 are executed.

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