Method for smooth switching between grid-forming and grid-following control in full-power wind power converter

Abstract

The application discloses a kind of network construction and follow network control's no fluctuation switching method in full-power wind power converter, when converter is in follow network control, converter network side control bus and reactive power, machine side carries out power control, when converter is in network construction control, network side uses virtual synchronous machine control, machine side controls bus.When in network construction operation, the running angle of follow network and machine network side outer ring integrator real-time value are calculated, when in follow network operation, the running angle of network construction and machine network side outer ring integrator real-time value are calculated, when switching, angle switching, the mode of step switching control ring can reduce fluctuation in switching process, using reasonable switching timing, finally obtain optimal online follow network network construction switching control algorithm.The application can flexibly switch control mode according to power grid demand, improve system stability and economy, with higher engineering practical value.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wind power generation and power electronics, and particularly relates to a wave-free switching method for grid-forming and grid-following control in a full-power wind power converter. BACKGROUND

[0002] To address the problems brought by high penetration of new energy, grid-forming and grid-following switching of a single wind turbine is determined by a station or dispatch in real time, which requires no disconnection from the grid, small fluctuation, no triggering of hardware protection of the turbine, no impact during full-load switching, and arbitrary switching by the station or dispatch, so the online switching control algorithm must be disturbance-free, highly reliable, and cannot affect the hardware life of any turbine, and therefore a reasonable online switching control algorithm is important. SUMMARY

[0003] The application is proposed to overcome the stability challenges brought by large impedance fluctuation of the power grid and weak grid characteristics under high penetration of new energy, and the problems of slow power regulation of grid-forming converters and poor strong grid adaptability, and aims to provide a wave-free switching method for grid-forming and grid-following control in a full-power wind power converter.

[0004] The application is implemented through the following technical solutions:

[0005] A wave-free switching method for grid-forming and grid-following control in a full-power wind power converter, comprising the following steps:

[0006] (I) When the converter is in grid-forming mode operation, the grid-side of the converter adopts virtual synchronous machine control, the machine-side of the converter controls the bus, and the running angle when switching to grid-following mode operation, the real-time value of the machine-side outer loop integrator, and the real-time value of the grid-side outer loop integrator are calculated, and the grid-connected point active current under the current active power and reactive power and at the grid-following operation angle is calculated in real time I d , reactive current I q ;

[0007] When the converter receives an instruction to switch to grid-following mode operation, the following operations are performed in sequence:

[0008] (I-ⅰ) Assign the machine-side outer loop integrator in grid-forming mode operation to the machine-side outer loop integrator in grid-following mode operation;

[0009] (I-ⅱ) Assign the grid-connected point active current under the current active power and at the grid-following operation angle to the DC bus voltage loop integrator in grid-following mode operation; I d

[0010] ​(I-ⅲ) the reactive current of the grid-connected point under the current reactive power and the angle of the grid-following operation angle I q is assigned to the reactive ring integrator of the grid-following operation mode;

[0011] (I-ⅳ) the grid-side internal potential angle of the grid-forming operation mode is switched to the operation angle of the grid-following operation mode;

[0012] (I-ⅴ) the grid-side outer ring integrator and the machine-side outer ring integrator of the grid-forming operation mode are cleared;

[0013] (II) when the converter is in the grid-following operation mode, the converter grid-side control bus and reactive power, the converter machine-side power control, and the operation angle of the grid-forming operation mode, the real-time value of the machine-side outer ring integrator and the real-time value of the grid-side outer ring integrator are calculated, and the internal potential angle of the grid-forming operation mode under the current active power and reactive power is calculated in real time θ VSG , the grid d shaft voltage U d , the grid q shaft voltage U q , the grid-connected point active current I d and reactive current I q ;

[0014] When the converter receives the instruction to switch to the grid-forming operation mode, the following operations are performed in sequence:

[0015] (II-ⅰ) the machine-side outer ring integrator of the grid-following operation mode is assigned to the machine-side outer ring integrator of the grid-forming operation mode;

[0016] (II-ⅱ) the grid-side phase-locked angle is switched to the internal potential angle ;

[0017] (II-ⅲ) the grid-connected point active current I d , reactive current I q under the current active power and reactive power and in the grid-forming operation mode is assigned to the grid-side d shaft, q shaft current given value;

[0018] (II-ⅳ) after a delay of one control period (ts), the grid-connected point active current I d and reactive currentI q assigned to d axis, q axis voltage loop integrator, cut-in middle ring voltage loop;

[0019] (Ⅱ-ⅴ) After delaying for another control period (ts), cut in the voltage amplitude control and virtual synchronous machine control;

[0020] (Ⅱ-ⅵ) The machine side outer loop integrator and the grid side outer loop integrator are cleared.

[0021] In the above technical solution, the control period (ts) in the field of wind power converter is within 200us.

[0022] In the above technical solution, the operating angle when the grid-following mode is running is the phase-locked angle θ PLL ;

[0023] The machine side outer loop integrator real-time value when the grid-following mode is running is the same as the machine side outer loop integrator real-time value when the grid-constructing mode is running (the machine side outer loop of the grid-following is the torque ring or the power ring, and the output is the active current given to the machine side, corresponding q axis, and the value is equal to the machine side outer loop integrator real-time value when the grid-constructing mode is running, only variable assignment is needed; while the machine side d axis corresponding outer loop is the flux-weakening ring, which is the same as the grid-following and grid-constructing control ring, so it does not need to be processed);

[0024] The grid side outer loop integrator real-time value when the grid-following mode is running includes the DC bus voltage ring integrator real-time value I d and the reactive ring integrator real-time value I q (The grid side outer loop integrator when the grid-following mode is running includes the DC bus voltage ring and the reactive ring integrator, the DC bus voltage ring outputs the active current given, that is I d , the reactive ring outputs the reactive current given, that is I q , I d and I q The calculation method is to use the Uabc instantaneous voltage and θ PLL to calculate U d , U q , combined with the current active power P and the reactive power Q , using the formula, to get Id 、 I q )。

[0025] In the above technical solution, the phase-locked angle θ PLL The calculation formula is:

[0026]

[0027] In the formula: w is the phase-locked angle frequency, with the unit of rad / s; K p is the phase-locked loop proportional coefficient, dimensionless; U q is the grid q-axis voltage, with the unit of V; K i is the phase-locked loop integral coefficient, dimensionless; t is the program execution period, with the unit of s seconds; θ PLL is the grid q-axis voltage, with the unit of V;

[0028] In the above technical solution, the real-time value of the DC bus voltage loop integrator I d and the real-time value of the reactive power loop integrator I q The calculation method is: using the instantaneous voltage Uabc and θ PLL to calculate θ PLL the corresponding grid d axis voltage U d and the grid q axis voltage U q , and combining the current active power P and the reactive power Q , the calculation formula of the real-time value of the DC bus voltage loop integrator I d and the real-time value of the reactive power loop integrator I q is obtained.

[0029] In the above technical solution, the grid forming operating angle is the internal potential angle θ VSG ;

[0030] The real-time value of the machine-side outer loop integrator in the grid following mode is the same as the real-time value of the machine-side outer loop integrator in the grid forming mode (the bus loop integrator of the machine-side q axis is equal to the machine-side grid following operating qThe outer loop integrator output corresponding to the axis on the machine side d The outer loop corresponding to the axis is consistent with the grid and the grid, without the need to change;

[0031] The grid side outer loop integrator when the grid mode runs includes the real-time value of the DC bus voltage loop integrator I d And the real-time value of the reactive loop integrator I q .

[0032] In the above technical solution, the real-time value of the DC bus voltage loop integrator when the grid mode runs I d And the real-time value of the reactive loop integrator I q The calculation method is: first, using the instantaneous voltage Uabc and θ VSG Calculate the angle θ VSG Corresponding to the grid d Axis voltage U d And the grid q Axis voltage U q , combined with the current active power P And the reactive power Q , using the real-time value of the DC bus voltage loop integrator I d And the real-time value of the reactive loop integrator I q The calculation formula is obtained.

[0033] In the above technical solution, the calculation formula of the active current I d Is:

[0034]

[0035] The calculation formula of the reactive current I q Is:

[0036]

[0037] In the above formula: P The active power is W; Q The reactive power is Var; U d The d Axis voltage is V; U q The q Axis voltage is V.

[0038] In the above technical solution, the internal potential angle θ VSG The calculation formula is:

[0039]

[0040] In the formula: is the internal potential angle, in rad / s; is the operating angle of the grid, in rad / s; is the power angle, in rad / s.

[0041] In the above technical solution, the power angle δ eg By using inverse calculation, the following is obtained:

[0042] In the formula: is the active power, in W; E is the internal potential given filter value, in V; is the grid voltage amplitude, in V; X is the virtual impedance, in Ω.

[0043] The beneficial effects of the present application are:

[0044] The present application provides a non-fluctuation switching method for grid construction and grid following control in a full-power wind power converter, which can flexibly switch the control mode according to the grid demand, improve the system stability and economy, and has high engineering practical value. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a MATLAB digital simulation effect diagram (Uabc, Iabc, Udc1 and Udc2);

[0046] Figure 2 is a MATLAB digital simulation effect diagram (sUabc, slabc, Power and RePower);

[0047] Figure 3 is a semi-physical simulation effect diagram of switching from grid construction to grid following in a semi-physical test;

[0048] Figure 4 is a semi-physical simulation effect diagram of switching from grid following to grid construction in a semi-physical test. DETAILED DESCRIPTION

[0049] In order to enable the personnel in the technical field to better understand the technical solutions of the present application, the technical solutions of the present application will be further described below in combination with the drawings of the specification and through specific embodiments.

[0050] Example 1

[0051] A method for switching between grid-forming and grid-following control without fluctuation in a full-power wind power converter,

[0052] When the converter is in grid-following control, the grid-side control bus and reactive power of the converter, and the machine-side performs power control; when the converter is in grid-forming control, the grid-side of the converter adopts virtual synchronous machine (VSG) control, and the machine-side controls the bus; when the converter is in grid-forming operation, the running angle of grid-following and the real-time value of the machine-grid side outer loop integrator are calculated; when the converter is in grid-following operation, the running angle of grid-forming and the real-time value of the machine-grid side outer loop integrator are calculated; when switching between grid-forming and grid-following control, the angle switching and step-by-step switching control ring can reduce the fluctuation in the switching process, and a reasonable switching timing is adopted to ultimately obtain an optimal online grid-forming and grid-following switching method.

[0053] Specifically, the following steps are included:

[0054] (I) When the converter is in grid-forming mode operation, the grid-side of the converter adopts virtual synchronous machine control, the machine-side of the converter controls the bus, and the running angle, the real-time value of the machine-side outer loop integrator and the real-time value of the grid-side outer loop integrator when switching to grid-following mode operation are calculated, and the active current at the grid-connected point under the current active power and reactive power and the angle of grid-following operation is calculated in real time I d and the reactive current at the grid-connected point I q ;

[0055] When the converter receives an instruction to switch to grid-following mode operation, the following operations are performed in sequence:

[0056] (I-ⅰ) Assign the machine-side outer loop integrator in grid-forming mode operation to the machine-side outer loop integrator in grid-following mode operation;

[0057] (I-ⅱ) Assign the active current at the grid-connected point under the current active power and the angle of grid-following operation to the DC bus voltage ring integrator in grid-following mode operation; I d ;

[0058] (I-ⅲ) Assign the reactive current at the grid-connected point under the current reactive power and the angle of grid-following operation to the reactive ring integrator in grid-following mode operation; I q ;

[0059] (I-ⅳ) Switch the grid-side internal potential angle in grid-forming mode operation to the running angle in grid-following mode operation;

[0060] (I-ⅴ) Clear the machine-side outer loop integrator and the grid-side outer loop integrator in grid-forming mode operation.

[0061] Figure 1 、 2 The moment of 3s and Figure 3 are the moment of full load switching in network construction in digital simulation and semi-physical simulation, respectively. It can be seen that the bus fluctuation and power fluctuation are small, which meets the demand of actual prototype and does not trigger any hardware protection of the unit and cause additional problems.

[0062] (II) When the converter is in the grid-following mode, the bus and the reactive power of the grid side of the converter are controlled, the power of the machine side is controlled, and the running angle, the real-time value of the machine side outer loop integrator and the real-time value of the grid side outer loop integrator when switching to the network construction mode are calculated, and the internal potential angle of the network construction mode under the current active power and reactive power is calculated in real time θ VSG , grid d axis voltage U d , grid q axis voltage U q , active current I d and reactive current I q of the grid-connected point;

[0063] When the converter receives the instruction to switch to the network construction mode, the following operations are performed in sequence:

[0064] (II-ⅰ) Assign the machine side outer loop integrator in the grid-following mode to the machine side outer loop integrator in the network construction mode, so that the energy transmitted to the bus by the machine side is consistent with that before switching;

[0065] (II-ⅱ) Switch the grid side phase locking angle to the internal potential angle ;

[0066] (II-ⅲ) Assign the active current I d and the reactive current I q of the grid-connected point under the current active power and reactive power in the network construction mode to the given value of the d axis and q axis current of the network side in the network construction mode;

[0067] (II-ⅳ) After delaying for one control period (ts), assign the active current I d and the reactive current I q of the grid-connected point under the current active power and reactive power in the network construction mode to the given value of the d axis and qThe shaft voltage loop integrator cuts into the middle voltage loop ring;

[0068] (II-V) After delaying for another control period (ts), cut into the voltage amplitude control and virtual synchronous machine control;

[0069] (II-V) The machine side outer loop integrator and the network side outer loop integrator are cleared.

[0070] Figure 1 、 2 The 3s moment and Figure 4 are the moments of full load switching in the network simulation and semi-physical simulation, and when the angle switching and control loop step switching are used, it can be seen that the bus fluctuation and power fluctuation are small, which meets the needs of the actual prototype and does not trigger any hardware protection of the unit and cause additional problems.

[0071] In summary, by using the process quantity of the mode to be cut in advance, the angle switching and step switching when switching, and reasonable switching timing, the optimal online network switching control algorithm is obtained, and it is fully verified on the semi-physical simulation.

[0072] In the application, the operating angle of the network is a phase-locked angle θ PLL The phase-locked angle is calculated according to the phase-locked loop theory, and the phase-locked angle θ PLL The calculation formula of the phase-locked angle is:

[0073]

[0074] In the formula: w The phase-locked angle frequency is rad / s, radian per second; K p The phase-locked loop proportion coefficient is dimensionless; U q The voltage of the grid q axis is V, volt; K i The phase-locked loop integral coefficient is dimensionless; t The program execution period is s, second; θ PLL The operating angle of the network is rad, radian.

[0075] In the application, the real-time value of the network side outer loop integrator is the real-time value of the shaft current d The real-time value of the network side outer loop integrator is the real-time value of the shaft current I d . q I q ​​

[0076] In the present application, the d shaft current I d The calculation formula is:

[0077]

[0078] The q shaft current I q The calculation formula is:

[0079]

[0080] In the above formula: P is the active power, unit W, watt; Q is the reactive power, unit Var, var; U d is d shaft voltage, unit V, volt; U q is q shaft voltage, unit V, volt.

[0081] The d shaft current I q And q shaft current I q The calculation formula is:

[0082] (a) According to the power transmission theory, the expression of the active power transmitted by the VSG to the power grid is obtained;

[0083] The expression of the power transmission theory is:

[0084]

[0085] In the formula: is the active power, unit W, watt; is the total resistance in the line, unit Ω, ohm; is the total inductance in the line, unit H, henry; is the system angular frequency, unit rad / s, radian per second; is the internal potential, unit V, volt; is the grid voltage, unit V, volt; is the power angle, unit rad / s, radian per second;

[0086] When the resistive component in the transmission line is ignored, the expression of the active power transmitted by the VSG to the power grid is:

[0087]

[0088] wherein: X Z is the total impedance between the internal potential of the VSG and the grid, in Ω, ohm; θ is the power angle, in rad / s, radian per second; V is the grid voltage amplitude, in V, volt; V is the internal potential, in V, volt;

[0089] (b) the power angle calculation formula is derived from the expression of the active power transmitted by the VSG to the grid, and the power angle calculation formula is:

[0090]

[0091] wherein: θ is the power angle, in rad / s, radian per second; P is the active power transmitted by the VSG to the grid, in W, watt; Z is the total impedance between the internal potential of the VSG and the grid, in Ω, ohm; V is the grid voltage amplitude, in V, volt; V is the internal potential, in V, volt;

[0092] (c) the current calculation formula is derived according to the instantaneous power calculation theory;

[0093] The expression of the instantaneous power calculation theory is:

[0094]

[0095] wherein: P P is the active power, in W, watt; Q Q is the reactive power, in Var, var; U d V is d the shaft voltage, in V, volt; U q V is q the shaft voltage, in V, volt; I d I is d the shaft current, in A, ampere; I q I is q the shaft current, in A, ampere.

[0096] The current calculation formula is:

[0097] .

[0098] In the present application, the operating angle of the network is the internal potential angle θVSG , internal potential angle θ VSG The calculation formula is:

[0099]

[0100] Where: is the internal potential angle, in rad / s; is the running angle of the network, the unit is rad / s; is the power angle, in rad / s.

[0101] The switching method of the present invention is verified by digital simulation and semi-physical simulation of the converter. The verification results are as follows: Figures 1 to 4 ;

[0102] Figures 1 to 4 All horizontal axes in represent time;

[0103] Figure 1 The ordinate corresponding to Uabc is the instantaneous value of the grid phase voltage; the ordinate corresponding to Iabc is the instantaneous value of the grid phase current; the ordinates corresponding to Udc1 and Udc2 are the instantaneous values ​​of the DC bus voltage;

[0104] Figure 2 The ordinate corresponding to sUabc is the instantaneous value of the motor phase voltage; the ordinate corresponding to sIabc is the instantaneous value of the motor phase current; the ordinate corresponding to Power is the active power of the grid; the ordinate corresponding to RePower is the reactive power of the grid;

[0105] Figure 3 In the above figure, the vertical coordinates of the two curves are the instantaneous value of DC bus voltage 1 and the instantaneous value of DC bus voltage respectively; Figure 3 In the figure below, the vertical axis corresponding to line CH28:3473 (dark blue line) is the active power of the power grid; the vertical axis corresponding to line CH29:3477 (light blue line) is the reactive power of the power grid;

[0106] Figure 4 and Figure 3 The vertical coordinates corresponding to the middle curves have the same meaning.

[0107] The rated power of the converter in digital simulation and hardware-in-the-loop simulation is 3MW.

[0108] MATLAB digital simulation process is as follows Figure 1 、 2 :

[0109] The electrical quantities are as follows:

[0110] Uabc: grid side line voltage sUabc: generator side line voltage;

[0111] Iabc: grid-side three-phase current sIabc: machine-side three-phase current;

[0112] Udc1: bus 1 Power: grid-side active power;

[0113] Udc2: bus 2 RePower: grid-side reactive power;

[0114] As Figure 1 , 2 , the MATLAB array simulation process includes network construction and machine operation, active full load, reactive 0, cut and network operation, active load reduction, reactive full production, active full production, cut and network operation, the whole simulation process simulates the most severe and random switching test working condition in the actual switching process, and the hardware protection is not triggered at the switching moment. The voltage and current disturbance brought by switching can be completely tolerated by the converter, realizing the non-fluctuation switching of network construction and network following.

[0115] As Figure 3 shown, at 0 seconds, CH11:2120 line (purple line) and CH10:2110 line (green line) represent the fluctuations of the two DC buses respectively, CH28:3473 line (dark blue line) represents the fluctuation of grid active power, and CH29:3477 line (light blue line) represents the fluctuation of grid reactive power. At Figure 1 the 3rd second of Udc1 and Udc2 in digital simulation, the fluctuations of the two buses occur, Figure 2 the 3rd second of Power and RePower in digital simulation, the fluctuations of active power and reactive power occur; Figure 3 the 0th second and Figure 1 , Figure 2 the 3rd second are the same action time points of semi-physical simulation and digital simulation, and the switching between network construction and network following occurs at this time point. It can be seen that in the semi-physical simulation, the fluctuations of the buses and the power fluctuations are relatively small at the moment of full load network construction and network following. This fluctuation can be completely tolerated in the transient operation of the converter, and the waveform trend is consistent with that of the digital simulation, proving the feasibility of this method in actual engineering.

[0116] As Figure 4 shown, the same as Figure 3 , CH11:2120 line (purple line) and CH10:2110 line (green line) represent the fluctuations of the two DC buses respectively, CH28:3473 line (dark blue line) represents the fluctuation of grid active power, and CH29:3477 line (light blue line) represents the fluctuation of grid reactive power. At Figure 1 the 8th second of Udc1 and Udc2 in digital simulation, the fluctuations of the two buses occur, Figure 2 the 8th second of Power and RePower in digital simulation, the fluctuations of active power and reactive power occur; Figure 40.77 seconds and Figure 1 , Figure 2 8 seconds of the half-physical simulation and the same action time point of the digital simulation, the switching of the net and the network is occurred, it can be seen that in the half-physical simulation, the bus fluctuation and the power fluctuation are relatively small in the full-load net and network switching moment, the fluctuation can be completely tolerated in the transient operation of the converter, and the waveform trend is consistent with the digital simulation, in addition, the step switching method divides a large disturbance into three small disturbances, which is greatly beneficial to the hardware and software control of the unit, and proves that the method has superiority in the actual engineering.

[0117] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application can be easily thought by any person skilled in the art in the technical field, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for seamless switching between grid-forming and grid-following control in a full-power wind power converter, characterized in that: The method comprises the following steps: (I) when the converter is in the grid-connected mode operation, the converter grid side adopts virtual synchronous machine control, the converter machine side control bus, calculates the running angle when switching to the grid-following mode operation, the real-time value of the machine side outer loop integrator and the real-time value of the grid side outer loop integrator, and calculates the grid-connected point active current in real time under the current active power and reactive power and the angle of grid-following operation I d , reactive current I q ; When the converter receives an instruction to switch to grid-connected mode operation, a grid-connected switching operation is performed; The grid-connected switching operation comprises the following steps: (I-ⅰ) Assigning the machine-side outer loop integrator in the grid-connected mode operation to the machine-side outer loop integrator in the grid-connected mode operation; (I-ii) the active current at the point of interconnection at the current active power and at the angle of the grid-following mode of operation I d is assigned to the DC bus voltage loop integrator at the grid-following mode of operation (I-III) the reactive current at the point of interconnection when the current reactive power and the angle are those of the grid-following mode of operation I q is assigned to the reactive ring integrator when operating in the grid-following mode (I-IV) the potential angle inside the network mode running network side Switch to the operating angle when running in the network mode (I-ⅴ) Clearing the machine-side outer loop integrator and the grid-side outer loop integrator in the grid-connected mode operation; (II) when the converter is in grid-following mode operation, the grid-side control bus and reactive power of the converter, the machine-side power control, the switching angle calculation for the grid-forming mode operation, the machine-side outer loop integrator real-time value and the grid-side outer loop integrator real-time value, the real-time calculation of the internal potential angle in the current active power and reactive power under the grid-forming mode operation θ VSG , grid d shaft voltage U d , grid q shaft voltage U q , grid I d active current I q and reactive current When the converter receives an instruction to switch to grid-connected mode operation, a grid-connected switching operation is performed; The grid-connected switching operation comprises the following steps: (Ⅱ-ⅰ) Assigning the machine-side outer loop integrator in the grid-connected mode operation to the machine-side outer loop integrator in the grid-connected mode operation; (II-ii) switching to the grid-side phase-locked angle switching to the internal potential angle ; (II-III) Real-time calculation of the grid-connected point active current with the grid-forming mode running at the current active power and reactive power I d , reactive current I q assigned to the grid-forming grid side d axis, q axis current given value; (II-IV) After delaying a control cycle, the current active power and reactive power are assigned to the active current and reactive current of the grid-connected point in the grid-forming mode I d and reactive current I q assigned to d axis, q axis voltage loop integrator, cut-in middle voltage loop (Ⅱ-ⅴ) After delaying for another control period, the voltage amplitude control and the virtual synchronous machine control are switched in; (Ⅱ-ⅵ) Clearing the machine-side outer loop integrator and the grid-side outer loop integrator in the grid-connected mode operation.

2. The method for seamless switchover of grid-forming and grid-following control in a full-power wind power converter according to claim 1, characterized in that: The running angle of the follow net mode running is a phase-locked angle θ PLL ; The real-time value of the machine-side outer loop integrator in the grid-connected mode operation is the same as the real-time value of the machine-side outer loop integrator in the grid-connected mode operation; The network side outer loop integrator in the follow-up network mode operation includes a bus loop integrator and a reactive loop integrator, the real-time value of the bus loop integrator is active current I d The real-time value of the reactive loop integrator is reactive current I q .

3. The method for seamless switchover of grid-forming and grid-following control in a full-power wind power converter according to claim 2, characterized in that: The phase-locked angle θ PLL The calculation formula is: In the formula: w is the phase-locked angle frequency, with the unit of rad / s; K p is the phase-locked loop proportional coefficient, dimensionless; U q Vgridq is the grid q-axis voltage, in V; K i Kp is the phase-locked loop integral coefficient, dimensionless; t is the program execution period in seconds; θ PLL is the angle of the net in radians.

4. The method for seamless switchover of grid-forming and grid-following control in a full-power wind power converter according to claim 2, characterized in that: Bus voltage loop integrator real-time numerical active current I d And reactive loop integrator real-time numerical reactive current I q The calculation method is: using Uabc instantaneous voltage and θ PLL Calculate θ PLL The corresponding power grid d Axis voltage U d And power grid q Axis voltage U q , combined with the current active power P And reactive power Q , using the DC bus voltage loop integrator real-time numerical value I d And reactive loop integrator real-time numerical value I q The calculation formula is obtained.

5. The seamless switchover between grid-forming and grid-following control in a full-power wind power converter according to claim 1, characterized in that: The network-constructed operating angle is an internal potential angle θ VSG ; The network mode runtime network side outer loop integrator includes a DC bus voltage loop integrator real-time value I d And a reactive power loop integrator real-time value I q .

6. The seamless switchover between grid-forming and grid-following control in a full-power wind power converter according to claim 5, characterized in that: Real-time value of the DC bus voltage loop integrator when the grid-connected mode is running I d and the real-time value of the reactive loop integrator I q The calculation method is: first use the instantaneous voltage of Uabc and θ VSG The calculated angle is θ VSG Corresponding power grid d Shaft voltage U d and power grid q Shaft voltage U q , combined with the current active power P and reactive power Q , using the real-time value of the DC bus voltage loop integrator I d and real-time value of reactive loop integrator I q The calculation formula is obtained.

7. The seamless switchover between grid-forming and grid-following control in a full-power wind power converter according to claim 4 or 6, characterized in that: the active current I d The calculation formula is: The reactive current I q The calculation formula is: In the above formulae: P P is the active power in W. Q For reactive power, in Var; U d For d Shaft voltage, in V; U q For q Shaft voltage, in V.

8. The seamless switchover between grid-forming and grid-following control in a full-power wind power converter according to claim 5, characterized in that: The inner potential angle θ VSG The calculation formula is: Where: is the internal potential angle, in rad / s; is the running angle of the network, the unit is rad / s; is the power angle, in rad / s.

9. The seamless switchover between grid-forming and grid-following control in a full-power wind power converter according to claim 8, characterized in that: The power angle δ eg Utilizing Obtained by back calculation, wherein: is the active power in W; E is the internal voltage given filter value in V; is the grid voltage amplitude in V; X is the virtual impedance in Ω.

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