Direct-current voltage synchronous full-power wind turbine control method and system

Abstract

The application provides a direct-current voltage synchronous full-power wind turbine control method and system, which comprises the following steps: inertia response of the wind turbine is realized without directly detecting the grid frequency; information reflecting the grid frequency change rate is obtained through current ripple generated by power deviation of the machine and the grid on the direct-current capacitor, so that the active inertia response of the full-power wind turbine to the grid frequency can be realized without adding a differential link; inertia power transmission coefficient of the machine side converter is calculated in real time through the generator speed, so that the optimal rotational inertia of the wind turbine is extracted to support the grid frequency change in the full speed range of the generator; and the machine terminal voltage autonomous compensation link is added to the framework of the AC voltage droop plus reactive power cascade control of the grid side converter, so that the active support to the grid voltage is realized.

Description

Technical Field

[0001] This invention relates to the fields of wind power generation technology and power electronic converter control technology in power systems. Specifically, it relates to a control method and system for DC voltage synchronous full-power wind turbine generators, and more specifically, it relates to a frequency and voltage active support control method and system for DC voltage synchronous full-power wind turbine generators. Background Technology

[0002] With the large-scale grid connection of power-electronic new energy power generation units such as wind power and photovoltaics with inertia-free response characteristics, the power system faces a serious problem of insufficient equivalent inertia, which severely threatens the frequency security and stability of the power system. DC voltage synchronous full-power wind turbine units analogize the DC capacitor voltage of the grid-connected converter to the rotational angular velocity of a synchronous generator, the modulation voltage to the flux linkage of a synchronous generator, and the inertial time constant of the DC capacitor to the inertial time constant of a synchronous generator. The DC voltage is normalized, multiplied by the grid frequency rating, and integrated to obtain the angle of the modulation voltage vector of the grid-connected converter. The amplitude of the modulation voltage vector is derived from the amplitude of the reactive power closed-loop plus the grid voltage rating. This method is called DC voltage synchronous control. DC voltage synchronous control enables the grid-connected converter to achieve autonomous synchronous grid control without a phase-locked loop. Under this control method, the DC voltage can reflect changes in the grid frequency in real time. Based on this law, the rotational inertia of the wind turbine is extracted by detecting the rate of change of the DC voltage in the turbine-side converter, thereby realizing the inertia response function of the unit. However, this control method still requires a differential element in the inertia transfer control loop of the turbine-side converter. In practice, high-pass filters are often used instead, making the inertia transfer control loop complex. At the same time, the inertia transfer adjustment coefficient is generally taken as a constant. Considering the variable speed operation characteristics of wind turbines, this method of fixing the inertia transfer adjustment coefficient cannot fully utilize the energy stored in the unit or fully utilize the frequency support capability of the unit during grid frequency changes. Therefore, current DC voltage synchronous full-power wind turbines do not have optimal inertia response capability. In addition, the current mainstream control method still aims to control the reactive power of the unit and cannot achieve autonomous support control of AC voltage.

[0003] Therefore, in view of the shortcomings of the existing technology, there is an urgent need in this field to propose a frequency and voltage active support control method for DC voltage synchronous full-power wind turbine generators. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a DC voltage synchronous full-power wind turbine control system and method.

[0005] According to the present invention, a DC voltage synchronous full-power wind turbine control system includes: a grid-side converter synchronization angle control module 101, a grid-side converter AC voltage amplitude control module 102, a machine-side converter autonomous inertia transfer control module 103, and a machine-side converter torque-current control module 104.

[0006] The grid-side converter synchronization angle control module 101 is used to generate the rotation angle of the grid-side converter modulation voltage signal in the full-power wind turbine converter power generation system 100 while achieving constant DC voltage.

[0007] The grid-side converter AC voltage amplitude control module 102 is used to generate the amplitude of the modulated voltage signal of the grid-side converter in the full-power wind turbine converter power generation system 100, so as to realize the active support control of the grid voltage by the full-power wind turbine converter power generation system 100.

[0008] The machine-side converter autonomous inertia transfer control module 103 is used to generate an additional torque signal that is proportional to the frequency change rate when the grid frequency changes, so as to realize the active extraction and control of the wind turbine rotational inertia by the machine-side converter in the full-power wind turbine converter power generation system 100.

[0009] The machine-side converter torque-current control module 104 is used to control the torque current of the machine-side converter in the full-power wind turbine converter power generation system 100, so as to realize the inertia response control of the full-power wind turbine converter power generation system 100 to the grid frequency while generating electricity normally.

[0010] Preferably, the grid-side converter synchronization angle control module 101 obtains the rotation angular frequency of the grid-side converter electrical signal by normalizing the DC voltage, and then integrates it to obtain the rotation angle of the grid-side converter electrical signal.

[0011]

[0012] Where, ω gsc ω is the rotational angular frequency of the control signal for the grid-side converter. n U is the rated angular frequency value of the mains voltage; dcref DC voltage setting; U dc This represents the actual value of the DC voltage; θ gsc This refers to the rotation angle of the electrical signal of the grid-side converter.

[0013] Preferably, the grid-side converter AC voltage amplitude control module 102 obtains the grid-side converter reactive power command value by passing the difference between the grid voltage set value and the actual value through a proportional controller, and then passes it through a reactive power control loop and adds the grid voltage set value to obtain the desired amplitude of the grid-side converter modulation voltage.

[0014] The grid voltage setpoint includes the voltage deviation value given by the substation, as well as the unit's own voltage compensation and stator voltage rating. The calculation formula is as follows:

[0015] U sref =U gn +ΔU ref1 +ΔU ref2 ;

[0016] Among them, U sref The setpoint for the mains voltage; U gn The rated value of the stator voltage; ΔU ref1 The voltage deviation value given by the station; ΔU ref2 This is the voltage compensation amount for the generator unit itself;

[0017] Unit self-voltage compensation ΔU ref2 The expression is calculated based on the active power of the unit:

[0018] ΔU ref2 =ΔU L +(ΔU H -ΔU L )·P g ;

[0019] Where, ΔU L This is the voltage compensation value when the unit power is zero; ΔU H This is the voltage compensation value when the unit power is at its rated power; P g This represents the active power output of the generator unit.

[0020] The reactive power command value of the grid-side converter is obtained by outputting the difference between the grid voltage setpoint and the actual value through a proportional controller. Its expression is:

[0021] Q gref =(U sref -U sm )·K V ;

[0022] Among them, Q gref U represents the reactive power command value of the grid-side converter. sm K represents the phase voltage amplitude of the power grid. V This refers to the AC voltage droop coefficient of the grid-side converter.

[0023] The desired amplitude of the modulated voltage of the grid-side converter is obtained by the difference between the grid voltage setpoint and the actual value, output by a proportional controller, and its expression is:

[0024]

[0025] Among them, U t Q represents the desired amplitude of the modulation voltage of the grid-side converter.g This represents the actual reactive power value of the grid-side converter. This is the proportional coefficient of the reactive power loop; The integral coefficient of the reactive power loop; ΔU gpss For grid-side converter control compensation voltage;

[0026] The expression for the control compensation voltage of the grid-side converter is:

[0027]

[0028] Among them, K pss T represents the stability control coefficient of the grid-side converter. p The filtering time constant of the stabilization control circuit.

[0029] Preferably, the autonomous inertia transfer control module 103 of the machine-side converter obtains the rate of change of DC capacitor voltage by dividing the deviation between the actual value of the active power of the machine-side converter and the actual value of the active power of the grid-side converter by the product of the DC capacitor voltage and the DC capacitor value; and multiplies the rate of change of DC capacitor voltage by the optimal inertia transfer coefficient to obtain the compensation torque of the full-power wind turbine generator.

[0030] The formula for calculating the compensation torque of a full-power wind turbine generator is as follows:

[0031]

[0032] Where, ΔT e The compensation torque for the inertial response mechanism; P m P represents the active power of the machine-side converter. g C represents the active power of the grid-side converter. dc K represents the DC bus capacitance value. COP The optimal inertia response coefficient;

[0033] The active power of the machine-side converter can be calculated from the three-phase current of the machine-side converter and the angular velocity of the motor. The calculation formula is as follows:

[0034]

[0035] Where, N p L represents the number of pole pairs of the motor. d and L q For the d-axis and q-axis inductance of the generator; I md and I mq ψ represents the d-axis and q-axis components of the generator stator current in a rotating coordinate system. r ω is the rated flux linkage of the generator; m The mechanical angular frequency of the generator;

[0036] The d-axis and q-axis components of the generator stator current in the rotating coordinate system are obtained from the three-phase stator current through rotating coordinate transformation, and their calculation formula is as follows:

[0037]

[0038] Where, θ r I represents the rotor position angle of the generator; ma I mb and I mc This represents the three-phase current value of the generator;

[0039] The formula for calculating the optimal inertia response coefficient is:

[0040]

[0041] Among them, J WT f is the moment of inertia of the wind turbine generator set. N The rated frequency of the power grid;

[0042] The active power calculation formula for the grid-side converter is as follows:

[0043]

[0044] Among them, U gd and U gq I represents the d-axis and q-axis components of the three-phase voltage of the power grid in the grid-side rotating coordinate system. gd and I gq These are the d-axis and q-axis components of the three-phase current of the grid-side converter in the grid-side rotating coordinate system.

[0045] The d-axis and q-axis components of the three-phase voltage in the rotating coordinate system are obtained from the three-phase voltage of the power grid through a rotating coordinate transformation, and their calculation formula is as follows:

[0046]

[0047] Among them, U ga U gb and U gc This represents the three-phase current value of the generator;

[0048] The d-axis and q-axis components of the three-phase current of the grid-side converter in the rotating coordinate system are obtained by transforming the three-phase current of the grid-side converter through rotating coordinates. The calculation formula is as follows:

[0049]

[0050] Among them, I ga I gb and I gc This represents the three-phase current value of the grid-side converter.

[0051] Preferably, the machine-side converter torque-current control module 104 includes:

[0052] The torque command given by the main controller is added with a compensation value to serve as the torque reference value of the unit. The torque reference value and feedback value are used to obtain the current command value through the torque controller. The current command value and feedback value are used to obtain the modulation voltage of the turbine-side converter through the current controller, thereby controlling the operation of the turbine-side converter to achieve inertia response control of the full-power wind turbine.

[0053] By inputting the torque setpoint and feedback value into the torque controller, the torque current command value of the machine-side converter can be obtained, and its expression is as follows:

[0054]

[0055] Among them, T e K represents the actual torque value of the generator. Pt K is the proportional coefficient of the torque control loop; It is the integral coefficient of the torque control loop.

[0056] A control method for a DC voltage synchronous full-power wind turbine generator provided by the present invention includes:

[0057] Step S1: Use the grid-side converter synchronization angle control module 101 to achieve constant DC voltage while generating the rotation angle of the grid-side converter modulation voltage signal in the full-power wind turbine converter power generation system 100;

[0058] Step S2: The grid-side converter AC voltage amplitude control module 102 is used to generate the amplitude of the modulated voltage signal of the grid-side converter in the full-power wind turbine converter power generation system 100, so as to realize the active support control of the grid voltage by the full-power wind turbine converter power generation system 100.

[0059] Step S3: The autonomous inertia transfer control module 103 of the machine-side converter generates an additional torque signal that is proportional to the rate of frequency change when the grid frequency changes, so as to realize the active extraction and control of the rotational inertia of the wind turbine by the machine-side converter in the full-power wind turbine converter power generation system 100.

[0060] Step S4: Use the torque-current control module 104 of the generator-side converter to control the torque current of the generator-side converter in the full-power wind turbine converter power generation system 100, so as to realize the inertia response control of the full-power wind turbine converter power generation system 100 to the grid frequency while generating electricity normally.

[0061] Preferably, the grid-side converter synchronization angle control module 101 obtains the rotation angular frequency of the grid-side converter electrical signal by normalizing the DC voltage, and then integrates it to obtain the rotation angle of the grid-side converter electrical signal.

[0062]

[0063] Where, ω gsc ω is the rotational angular frequency of the control signal for the grid-side converter. n U is the rated angular frequency value of the mains voltage; dcref DC voltage setting; U dc This represents the actual value of the DC voltage; θ gsc This refers to the rotation angle of the electrical signal of the grid-side converter.

[0064] Preferably, the grid-side converter AC voltage amplitude control module 102 obtains the grid-side converter reactive power command value by passing the difference between the grid voltage set value and the actual value through a proportional controller, and then passes it through a reactive power control loop and adds the grid voltage set value to obtain the desired amplitude of the grid-side converter modulation voltage.

[0065] The grid voltage setpoint includes the voltage deviation value given by the substation, as well as the unit's own voltage compensation and stator voltage rating. The calculation formula is as follows:

[0066] U sref =U gn +ΔU ref1 +ΔU ref2 ;

[0067] Among them, U sref The setpoint for the mains voltage; U gn The rated value of the stator voltage; ΔU ref1 The voltage deviation value given by the station; ΔU ref2 This is the voltage compensation amount for the generator unit itself;

[0068] Unit self-voltage compensation ΔU ref2 The expression is calculated based on the active power of the unit:

[0069] ΔU ref2 =ΔU L +(ΔU H -ΔU L )·P g ;

[0070] Where, ΔU L This is the voltage compensation value when the unit power is zero; ΔU H This is the voltage compensation value when the unit power is at its rated power; P g This represents the active power output of the generator unit.

[0071] The reactive power command value of the grid-side converter is obtained by outputting the difference between the grid voltage setpoint and the actual value through a proportional controller. Its expression is:

[0072] Q gref =(Usref -U sm )·K V ;

[0073] Among them, Q gref U represents the reactive power command value of the grid-side converter. sm K represents the phase voltage amplitude of the power grid. V This refers to the AC voltage droop coefficient of the grid-side converter.

[0074] The desired amplitude of the modulated voltage of the grid-side converter is obtained by the difference between the grid voltage setpoint and the actual value, output by a proportional controller, and its expression is:

[0075]

[0076] Among them, U t Q represents the desired amplitude of the modulation voltage of the grid-side converter. g This represents the actual reactive power value of the grid-side converter. This is the proportional coefficient of the reactive power loop; The integral coefficient of the reactive power loop; ΔU gpss For grid-side converter control compensation voltage;

[0077] The expression for the control compensation voltage of the grid-side converter is:

[0078]

[0079] Among them, K pss T represents the stability control coefficient of the grid-side converter. p The filtering time constant of the stabilization control circuit.

[0080] Preferably, the autonomous inertia transfer control module 103 of the machine-side converter obtains the rate of change of DC capacitor voltage by dividing the deviation between the actual value of the active power of the machine-side converter and the actual value of the active power of the grid-side converter by the product of the DC capacitor voltage and the DC capacitor value; and multiplies the rate of change of DC capacitor voltage by the optimal inertia transfer coefficient to obtain the compensation torque of the full-power wind turbine generator.

[0081] The formula for calculating the compensation torque of a full-power wind turbine generator is as follows:

[0082]

[0083] Where, ΔT e The compensation torque for the inertial response mechanism; P m P represents the active power of the machine-side converter. g C represents the active power of the grid-side converter. dc K represents the DC bus capacitance value. COP The optimal inertia response coefficient;

[0084] The active power of the machine-side converter can be calculated from the three-phase current of the machine-side converter and the angular velocity of the motor. The calculation formula is as follows:

[0085]

[0086] Where, N p L represents the number of pole pairs of the motor. d and L q For the d-axis and q-axis inductance of the generator; I md and I mq ψ represents the d-axis and q-axis components of the generator stator current in a rotating coordinate system. r ω is the rated flux linkage of the generator; m The mechanical angular frequency of the generator;

[0087] The d-axis and q-axis components of the generator stator current in the rotating coordinate system are obtained from the three-phase stator current through rotating coordinate transformation, and their calculation formula is as follows:

[0088]

[0089] Where, θ r I represents the rotor position angle of the generator; ma I mb and I mc This represents the three-phase current value of the generator;

[0090] The formula for calculating the optimal inertia response coefficient is:

[0091]

[0092] Among them, J WT f is the moment of inertia of the wind turbine generator set. N The rated frequency of the power grid;

[0093] The active power calculation formula for the grid-side converter is as follows:

[0094]

[0095] Among them, U gd and U gq I represents the d-axis and q-axis components of the three-phase voltage of the power grid in the grid-side rotating coordinate system. gd and I gq These are the d-axis and q-axis components of the three-phase current of the grid-side converter in the grid-side rotating coordinate system.

[0096] The d-axis and q-axis components of the three-phase voltage in the rotating coordinate system are obtained from the three-phase voltage of the power grid through a rotating coordinate transformation, and their calculation formula is as follows:

[0097]

[0098] Among them, U ga U gb and U gc This represents the three-phase current value of the generator;

[0099] The d-axis and q-axis components of the three-phase current of the grid-side converter in the rotating coordinate system are obtained by transforming the three-phase current of the grid-side converter through rotating coordinates. The calculation formula is as follows:

[0100]

[0101] Among them, I ga I gb and I gc This represents the three-phase current value of the grid-side converter.

[0102] Preferably, the machine-side converter torque-current control module 104 includes:

[0103] The torque command given by the main controller is added with a compensation value to serve as the torque reference value of the unit. The torque reference value and feedback value are used to obtain the current command value through the torque controller. The current command value and feedback value are used to obtain the modulation voltage of the turbine-side converter through the current controller, thereby controlling the operation of the turbine-side converter to achieve inertia response control of the full-power wind turbine.

[0104] By inputting the torque setpoint and feedback value into the torque controller, the torque current command value of the machine-side converter can be obtained, and its expression is as follows:

[0105]

[0106] Among them, T e K represents the actual torque value of the generator. Pt K is the proportional coefficient of the torque control loop; It is the integral coefficient of the torque control loop.

[0107] Compared with the prior art, the present invention has the following beneficial effects:

[0108] 1. The present invention simplifies the inertia response control of DC voltage synchronous control type full-power wind turbine units, and can extract the optimal rotational inertia of the wind turbine according to the wind turbine's rotational speed, thereby achieving optimal frequency support control of the unit for the power grid.

[0109] 2. The present invention enables DC voltage synchronous control type full-power wind turbine generators to have active voltage control function. The generator can actively compensate and control the port voltage according to the output active power, so as to realize the active voltage support control of the generator to the power grid.

[0110] 3. This invention innovates the control strategy of DC voltage synchronous control type full-power wind turbine, and utilizes the characteristic of DC voltage mapping to grid frequency. It obtains capacitor current through the power difference between the turbine and grid sides, and then indirectly obtains grid frequency change information. Compared with traditional control methods, it does not require the addition of complex software filters, which simplifies the control algorithm of the converter. It also provides optimal frequency support for the grid by dynamically adjusting the inertia transfer coefficient. Attached Figure Description

[0111] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0112] Figure 1 This is a schematic diagram of a DC voltage synchronous full-power wind turbine control system.

[0113] Figure 2 This is a schematic diagram of the synchronization angle control module of the grid-side converter in a DC voltage synchronous full-power wind turbine.

[0114] Figure 3 This is a schematic diagram of the AC voltage amplitude control module of the grid-side converter in a DC voltage synchronous full-power wind turbine.

[0115] Figure 4 This is a schematic diagram of the autonomous inertia transfer control module of the generator-side converter in a DC voltage synchronous full-power wind turbine.

[0116] Figure 5 This is a schematic diagram of the torque-current control module of the generator-side converter in a DC voltage synchronous full-power wind turbine. Detailed Implementation

[0117] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0118] The purpose of this invention is to provide a control method and system for a DC voltage synchronous full-power wind turbine. This method obtains the current value of the DC capacitor by measuring the power deviation between the turbine and grid sides, and uses the relationship between the DC capacitor voltage and current to obtain the DC voltage change rate. This allows the full-power wind turbine to respond to the grid frequency change rate without adding a differential circuit. Furthermore, the inertia of the wind turbine is calculated in real time based on its rotational speed, and the inertia transfer adjustment coefficient of the unit is dynamically adjusted to provide optimal inertia support to the grid within a wide speed range of the wind turbine. Finally, by adding an autonomous voltage compensation stage to the grid-side converter within the framework of AC voltage droop and reactive power cascade control, active support for the grid voltage is achieved.

[0119] According to the present invention, a control method and system for a DC voltage synchronous full-power wind turbine generator includes: calculating the active power value of the grid-side converter using the three-phase current and generator speed of the generator-side converter of the full-power wind turbine generator converter power generation system 100; calculating the active power value of the grid-side converter using the three-phase voltage and three-phase current of the grid-side converter; subtracting the active power of the grid-side converter from the active power of the generator-side converter and dividing by the product of the DC capacitor voltage and the DC capacitor value to obtain the rate of change of the DC capacitor voltage; multiplying the rate of change of the DC capacitor voltage by the optimal inertia transfer coefficient to obtain the compensation torque of the generator of the full-power wind turbine generator; and controlling the torque-current of the generator-side converter. Module 104 uses the compensation torque as part of the torque setpoint to obtain the torque current setpoint through the torque current coefficient, and obtains the modulation voltage of the generator-side converter through the current controller to control the operation of the generator-side converter, thereby realizing the inertia response control of the full-power wind turbine. The grid-side converter AC voltage amplitude control module 102 uses AC voltage droop control to obtain the reactive power command, and then passes it through the reactive power control loop and adds the grid voltage setpoint to obtain the modulation voltage amplitude of the grid-side converter. The AC voltage setpoint is based on the rated AC voltage with the addition of a compensation voltage that is linearly related to the output active power of the grid-side converter. At the same time, it receives the secondary voltage compensation value given by the station controller. By compensating the AC voltage setpoint, the unit effectively supports the grid voltage.

[0120] Example 1

[0121] According to the present invention, a DC voltage synchronous full-power wind turbine control system is provided, such as... Figure 1-5 As shown, it includes: a full-power wind turbine converter power generation system 100, a grid-side converter synchronization angle control module 101, a grid-side converter AC voltage amplitude control module 102, a machine-side converter autonomous inertia transfer control module 103, and a machine-side converter torque-current control module 104.

[0122] More specifically, the DC voltage synchronous full-power wind turbine converter power generation control system 100 includes a wind turbine generator, a machine-side converter, a DC capacitor bank, a DC unloader, a grid-side converter, and an AC filter circuit; wherein the machine-side converter and the grid-side converter can be selected as two-level converters and three-level converters.

[0123] The full-power wind turbine converter power generation system 100 is used to provide the grid-side voltage, grid-side current, DC voltage, machine-side current, and generator speed signals required for the control of the full-power wind turbine converter. Specifically, it provides a DC voltage signal to the grid-side converter synchronization angle control module 101; provides a DC voltage signal and a grid-side voltage signal to the grid-side converter AC voltage amplitude control module 102; provides a DC voltage signal, a grid-side voltage signal, a grid-side current, a machine-side current, and a generator speed signal to the machine-side converter autonomous inertia transfer control module 103; and provides a machine-side current signal to the machine-side converter torque-current control module 104.

[0124] The grid-side converter synchronization angle control module 101 is used to realize the phase control of the modulation voltage vector of the grid-side converter of the full-power wind turbine.

[0125] The grid-side converter AC voltage amplitude control module 102 is used to realize the amplitude control of the modulation voltage vector of the grid-side converter of the full-power wind turbine.

[0126] The autonomous inertia transfer control module 103 of the machine-side converter is used to realize the active inertia transfer control of the machine-side converter of the full-power wind turbine.

[0127] The machine-side converter torque-current control module 104 is used to realize the torque and current control of the machine-side converter of the full-power wind turbine.

[0128] More specifically, the grid-side converter synchronization angle control module 101 is used to generate the rotation angle of the grid-side converter electrical signal while achieving a constant DC voltage. The rotation angular frequency of the grid-side converter electrical signal is obtained by normalizing the DC voltage, and then integrated to obtain the rotation angle of the grid-side converter electrical signal. The calculation formula is as follows:

[0129]

[0130] Where, ω gsc ω is the rotational angular frequency of the control signal for the grid-side converter. n U is the rated angular frequency value of the mains voltage; dcref DC voltage setting; U dc This is the actual value of the DC voltage; G u The gain of the DC voltage synchronization circuit; T dc θ is the filtering time constant of the DC voltage synchronization circuit;gsc This refers to the rotation angle of the control signal for the grid-side converter.

[0131] The grid-side converter AC voltage amplitude control module 102 is used to realize the active support control of the unit for the grid voltage. By passing the difference between the grid voltage setpoint and the actual value through the proportional controller, the reactive power command value of the grid-side converter is obtained. Then, by passing through the reactive power control loop and adding the grid voltage setpoint, the desired amplitude of the grid-side converter modulation voltage is obtained. By increasing the amplitude of the grid-side converter modulation voltage, the active support control of the unit for the grid voltage can be realized.

[0132] The grid voltage setpoint consists of three parts: the voltage deviation value given by the power station, the unit's own voltage compensation, and the stator voltage rating. The calculation formula is as follows:

[0133] U sref =U gn +ΔU ref1 +ΔU ref2 ;

[0134] Among them, U sref The setpoint for the mains voltage; U gn The rated value of the mains voltage; ΔU ref1 The voltage deviation command given by the station; ΔU ref2 This is the voltage compensation value generated by the unit itself.

[0135] The voltage compensation value ΔU generated by the unit itself ref2 The expression is calculated based on the active power of the unit:

[0136] ΔU ref2 =ΔU L +(ΔU H -ΔU L )·P g ;

[0137] Where, ΔU L This is the voltage compensation value when the unit power is zero; ΔU H This is the voltage compensation value when the unit power is at its rated power; P g This represents the active power output of the generator unit.

[0138] The reactive power command value of the grid-side converter is obtained by outputting the difference between the grid voltage setpoint and the actual value through a proportional controller. Its expression is:

[0139] Q gref =(U sref -U sm )·K V ;

[0140] Among them, Q grefU represents the reactive power command value of the grid-side converter. sm K represents the phase voltage amplitude of the power grid. V This is the AC voltage droop coefficient for the grid-side converter.

[0141] The magnitude of the grid voltage that the grid-side converter aims to control is obtained by the difference between the grid voltage setpoint and the actual value, output by a proportional controller. Its expression is as follows:

[0142]

[0143] Among them, U t Q represents the amplitude of the modulated wave from the grid-side converter. g This represents the actual reactive power value of the grid-side converter. This is the proportional coefficient of the reactive power loop; The integral coefficient of the reactive power loop; ΔU gpss The control compensation voltage is used for the grid-side converter.

[0144] The expression for the control compensation voltage of the grid-side converter is:

[0145]

[0146] Among them, K pss T represents the stability control coefficient of the grid-side converter. p The filtering time constant of the stabilization control circuit.

[0147] The autonomous inertia transfer control module 103 of the generator-side converter is used to realize the active extraction control of the wind turbine's rotational inertia by the generator-side converter. The rate of change of DC capacitor voltage is obtained by dividing the deviation between the actual active power value of the generator-side converter and the actual active power value of the grid-side converter by the product of DC capacitor voltage and DC capacitor value. The compensation torque of the full-power wind turbine generator is obtained by multiplying the rate of change of DC capacitor voltage by the optimal inertia transfer coefficient. The active extraction control of the wind turbine's rotational inertia can be realized by adding a compensation torque proportional to the grid frequency change rate to the torque control of the wind turbine generator.

[0148] The formula for calculating the compensation torque of the unit when responding to the rate of change of the power grid frequency, i.e., the inertial response, is as follows:

[0149]

[0150] Where, ΔT e The compensation torque for the inertial response mechanism; P m P represents the active power of the machine-side converter. g C represents the active power of the grid-side converter. dc K represents the DC bus capacitance value. COP This is the optimal inertia response coefficient.

[0151] The active power of the machine-side converter can be calculated from the three-phase current of the machine-side converter and the angular velocity of the motor. The calculation formula is as follows:

[0152]

[0153] Where, N p L represents the number of pole pairs of the motor. d and L q For the d-axis and q-axis inductance of the generator; I md and I mq ψ represents the d-axis and q-axis components of the generator stator current in a rotating coordinate system. r ω is the rated flux linkage of the generator; m ω is the mechanical angular frequency of the generator.

[0154] The d-axis and q-axis components of the generator stator current in the rotating coordinate system are obtained from the three-phase stator current through rotating coordinate transformation, and their calculation formula is as follows:

[0155]

[0156] Where, θ r I represents the rotor position angle of the generator; ma I mb and I mc This represents the three-phase current value of the generator.

[0157] The formula for calculating the optimal inertia response coefficient is:

[0158]

[0159] Among them, J WT f is the moment of inertia of the wind turbine generator set. N This is the rated frequency of the power grid.

[0160] The active power calculation formula for the grid-side converter is as follows:

[0161]

[0162] Among them, U gd and U gq I represents the d-axis and q-axis components of the three-phase voltage of the power grid in the grid-side rotating coordinate system. gd and I gq These are the d-axis and q-axis components of the three-phase current of the grid-side converter in the grid-side rotating coordinate system.

[0163] The d-axis and q-axis components of the three-phase voltage in the rotating coordinate system are obtained from the three-phase voltage of the power grid through a rotating coordinate transformation, and their calculation formula is as follows:

[0164]

[0165] Among them, U ga U gb and U gc This represents the three-phase current value of the generator.

[0166] The d-axis and q-axis components of the three-phase current of the grid-side converter in the rotating coordinate system are obtained by transforming the three-phase current of the grid-side converter through rotating coordinates. The calculation formula is as follows:

[0167]

[0168] Among them, I ga I gb and I gc This represents the three-phase current value of the grid-side converter.

[0169] The torque-current control module 104 of the turbine-side converter is used to realize the current control of the turbine-side converter. By adding the compensation value to the torque command given by the main controller as the torque reference value of the unit, the torque reference value and the feedback value are used to obtain the current command value through the torque controller. The current command value and the feedback value are used to obtain the modulation voltage of the turbine-side converter through the current controller, thereby controlling the operation of the turbine-side converter to realize the inertia response control of the full-power wind turbine.

[0170] By inputting the torque setpoint and feedback value into the torque controller, the torque current command value of the machine-side converter can be obtained, and its expression is as follows:

[0171]

[0172] Among them, T e K represents the actual torque value of the generator. Pt K is the proportional coefficient of the torque control loop; It is the integral coefficient of the torque control loop.

[0173] The present invention also provides a DC voltage synchronous full-power wind turbine control system, which can be implemented by executing the process steps of the DC voltage synchronous full-power wind turbine control method. That is, those skilled in the art can understand the DC voltage synchronous full-power wind turbine control method as a preferred embodiment of the DC voltage synchronous full-power wind turbine control system.

[0174] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0175] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A direct voltage synchronous full power wind turbine control system, characterized in that, The application relates to a full-power wind turbine generator system (100) comprising a grid-side converter synchronous angle control module (101), a grid-side converter AC voltage amplitude control module (102), a machine-side converter autonomous inertia transmission control module (103) and a machine-side converter torque-current control module (104). The grid-side converter synchronous angle control module (101) is used for generating the rotation angle of the grid-side converter modulation voltage signal in the full-power wind turbine generator system (100) while realizing the constant DC voltage. The grid-side converter AC voltage amplitude control module (102) is used for generating the amplitude of the grid-side converter modulation voltage signal in the full-power wind turbine generator system (100) to realize the active support control of the full-power wind turbine generator system (100) on the grid voltage. The machine-side converter autonomous inertia transmission control module (103) is used for generating the additional torque signal proportional to the frequency change rate when the grid frequency changes to realize the active extraction control of the machine-side converter on the rotational inertia of the wind turbine in the full-power wind turbine generator system (100). The machine-side converter torque-current control module (104) is used for controlling the torque current of the machine-side converter in the full-power wind turbine generator system (100) to realize the inertia response control of the full-power wind turbine generator system (100) on the grid frequency while realizing normal power generation. The machine-side converter autonomous inertia transmission control module (103) obtains the change rate of the DC capacitor voltage by dividing the deviation between the actual active power of the machine-side converter and the actual active power of the grid-side converter by the product of the DC capacitor voltage and the DC capacitor capacity value; and obtains the compensation torque of the full-power wind turbine generator by multiplying the change rate of the DC capacitor voltage by the optimal inertia transmission coefficient. The compensation torque calculation formula of the full-power wind turbine generator is as follows: The grid-side converter synchronous angle control module (101) obtains the rotation angle frequency of the grid-side converter electrical signal by normalizing the DC voltage, and then integrates to obtain the rotation angle of the grid-side converter electrical signal. Wherein, ΔT e is the compensation torque of the inertia response unit; P m is the active power of the machine-side converter; P g is the active power of the grid-side converter; C dc is the DC bus capacitance value; K COP is the optimal inertia response coefficient; U dc is the actual value of the DC voltage.

2. The direct voltage synchronous full power wind turbine control system according to claim 1, characterized in that The grid-side converter AC voltage amplitude control module (102) obtains the grid-side converter reactive power instruction value by passing the difference between the grid voltage set value and the actual value through a proportional controller, and then obtains the expected amplitude of the grid-side converter modulation voltage by passing the grid-side converter reactive power instruction value through a reactive power control loop and adding the grid voltage set value. where ω gsc is the rotational angular frequency of the grid-side converter control signal; ω n is the nominal angular frequency value of the grid voltage; U dcref is the DC voltage setpoint; U dc is the actual value of the DC voltage; θ gsc is the rotational angle of the grid-side converter electrical signal.

3. The direct voltage synchronous full power wind turbine control system according to claim 2, characterized in that The grid voltage set value comprises the voltage deviation value given by the field station, the voltage compensation amount of the unit itself and the stator voltage rated value, and the calculation formula is as follows: The grid-side converter reactive power instruction value is obtained by passing the difference between the grid voltage set value and the actual value through a proportional controller, and the expression is as follows: U sref = U gn + ΔU ref1 + ΔU ref2 ; where U sref is the grid voltage setpoint; U gn is the rated value of the stator voltage; ΔU ref1 is the voltage deviation value given by the substation; ΔU ref2 is the voltage compensation value of the unit itself; Unit self voltage compensation amount ΔU ref2 According to the active power of the unit, the expression is: ΔU ref2 = ΔU L + (ΔU H - ΔU L ) · P g ; wherein ΔU L is the voltage compensation value when the unit power is zero; ΔU H is the voltage compensation value when the unit power is the rated power; P g is the active power value output by the unit; The expected amplitude of the grid-side converter modulation voltage is obtained by passing the difference between the grid voltage set value and the actual value through a proportional controller, and the expression is as follows: Q gref = (U sref - U sm ) · K V ; Wherein, Q gref is the reactive power instruction value of the grid-side converter; U sm is the grid phase voltage amplitude; K V is the AC voltage regulation coefficient of the grid-side converter; The expression of the grid-side converter control compensation voltage is as follows: Wherein, U t is the desired amplitude of the grid-side converter modulation voltage; Q g is the actual value of the grid-side converter reactive power; K Pq is the proportional coefficient of the reactive power loop; K Iq is the integral coefficient of the reactive power loop; ΔU gpss is the grid-side converter control compensation voltage; The active power of the machine-side converter can be calculated by the machine-side converter three-phase current and the angular velocity of the motor, and the calculation formula is as follows: Wherein, K pss is the grid-side converter stabilizing control coefficient; T p is the filter time constant of the stabilizing control link.

4. The direct voltage synchronous full power wind turbine control system according to claim 3, characterized in that The d-axis and q-axis components of the generator stator current in the rotating coordinate system are obtained by rotating coordinate transformation of the stator three-phase current, and the calculation formula is as follows: where N p is the number of pole pairs of the electric machine; L d and L q are the d-axis and q-axis inductances of the generator; I md and I mq are the d-axis and q-axis components of the generator stator current in the rotating reference frame; ψ r is the rated flux linkage value of the generator; ω m is the mechanical angular frequency of the generator; ​ where θ r is the rotor position angle of the generator; I ma , I mb , and I mc are the three-phase current values of the generator; The formula for calculating the optimal inertia response coefficient is: wherein J WT is the moment of inertia of the wind turbine; f N is the rated frequency of the power grid; The active power calculation formula of the grid-side converter is: wherein U gd and U gq are the d-axis and q-axis components of the grid three-phase voltage in the grid-side rotating coordinate system; I gd and I gq are the d-axis and q-axis components of the grid-side converter three-phase current in the grid-side rotating coordinate system; The d-axis and q-axis components of the grid three-phase voltage in the rotating coordinate system are obtained by rotating coordinate transformation of the grid three-phase voltage, and the calculation formula is: wherein U ga , U gb and U gc are the three-phase current values of the generator; The d-axis and q-axis components of the grid three-phase voltage in the rotating coordinate system are obtained by rotating coordinate transformation of the grid three-phase voltage, and the calculation formula is: where I ga , I gb , and I gc are the three-phase current values of the grid-side converter.

5. The direct voltage synchronous full power wind turbine control system according to claim 4, characterized in that The machine-side converter torque-current control module (104) comprises: The given torque command is added to the compensation value as the torque reference value of the unit, and the torque reference value and the feedback value are input into the torque controller to obtain the current command value; the current command value and the feedback value are input into the current controller to obtain the modulation voltage of the machine-side converter, thereby controlling the operation of the machine-side converter to realize the inertia response control of the full-power wind turbine generator; The torque command value and the feedback value are input into the torque controller to obtain the torque-current command value of the machine-side converter, and the expression is as follows: where T e is the actual torque value of the generator; K Pt is the proportional coefficient of the torque control loop; K It is the integral coefficient of the torque control loop.

6. A direct voltage synchronous full power wind turbine control method, characterized by It comprises: Step S1: using the grid-side converter synchronous angle control module (101) to realize the constant DC voltage and generate the rotation angle of the grid-side converter modulation voltage signal in the full-power wind turbine generator system (100); Step S2: using the grid-side converter AC voltage amplitude control module (102) to generate the amplitude of the grid-side converter modulation voltage signal in the full-power wind turbine generator system (100), and realizing the active support control of the grid voltage by the full-power wind turbine generator system (100); Step S3: the machine-side converter autonomous inertia transmission control module (103) generates an additional torque signal proportional to the frequency change rate when the grid frequency changes, realizing the active extraction control of the wind turbine rotational inertia by the machine-side converter in the full-power wind turbine generator system (100); Step S4: using the machine-side converter torque-current control module (104) to control the torque and current of the machine-side converter in the full-power wind turbine generator system (100), realizing the inertia response control of the grid frequency by the full-power wind turbine generator system (100) while generating electricity normally; The machine-side converter autonomous inertia transmission control module (103) obtains the change rate of the DC capacitor voltage by dividing the deviation between the actual active power of the machine-side converter and the actual active power of the grid-side converter by the product of the DC capacitor voltage and the DC capacitor capacity; the compensation torque of the full-power wind turbine generator is obtained by multiplying the change rate of the DC capacitor voltage by the optimal inertia transmission coefficient; The compensation torque calculation formula of the full-power wind turbine generator is: Wherein, ΔT e is the compensation torque of the inertia response unit; P m is the active power of the machine-side converter; P g is the active power of the grid-side converter; C dc is the DC bus capacitance value; K COP is the optimal inertia response coefficient; U dc is the actual value of the DC voltage.

7. The direct voltage synchronous full power wind turbine control method according to claim 6, characterized in that, The grid-side converter synchronous angle control module (101) obtains the rotation angle frequency of the grid-side converter electrical signal by normalizing the DC voltage, and then integrates to obtain the rotation angle of the grid-side converter electrical signal; where ω gsc is the angular frequency of the grid-side converter control signal; ω n is the nominal angular frequency value of the grid voltage; U dcref is the DC voltage setpoint; U dc is the actual value of the DC voltage; θ gsc is the electrical angle of the grid-side converter signal.

8. The direct voltage synchronous full power wind turbine control method according to claim 7, characterized in that, The grid-side converter AC voltage amplitude control module (102) obtains the grid-side converter reactive power command value by passing the difference between the grid voltage set value and the actual value through the proportional controller, and then obtains the expected amplitude of the grid-side converter modulation voltage through the reactive power control loop and adding the grid voltage set value; The grid voltage setting value comprises a voltage deviation value given by the site, a voltage compensation value of the unit itself, and a stator voltage rated value, and a calculation formula thereof is: U sref = U gn + ΔU ref1 + ΔU ref2 ; where U sref is the grid voltage setpoint; U gn is the rated value of the stator voltage; ΔU ref1 is the voltage deviation value given by the station; ΔU ref2 is the voltage compensation value of the unit itself; The unit's own voltage compensation amount ΔU ref2 According to the active power of the unit, the expression is: ΔU ref2 = ΔU L + (ΔU H - ΔU L ) · P g ; wherein ΔU L is the voltage compensation value when the unit power is zero; ΔU H is the voltage compensation value when the unit power is rated power; P g is the active power value output by the unit; The reactive power instruction value of the grid-side converter is obtained by a proportional controller output from a difference between the grid voltage setting value and an actual value, and an expression thereof is: Q gref = (U sref - U sm ) · K V ; wherein Q gref is the reactive power command value of the grid-side converter; U sm is the grid phase voltage amplitude; K V is the AC voltage regulation coefficient of the grid-side converter; The expected amplitude of the modulation voltage of the grid-side converter is obtained by a proportional controller output from a difference between the grid voltage setting value and an actual value, and an expression thereof is: Wherein, U t is the desired amplitude of the grid-side converter modulation voltage; Q g is the actual value of the grid-side converter reactive power; K Pq is the proportional coefficient of the reactive power loop; K Iq is the integral coefficient of the reactive power loop; ΔU gpss is the grid-side converter control compensation voltage; An expression of the compensation voltage of the grid-side converter is: wherein K pss is the stabilizing control coefficient of the grid-side converter; T p is the filter time constant of the stabilizing control link.

9. The direct voltage synchronous full power wind turbine control method according to claim 8, characterized in that, The active power of the machine-side converter can be calculated from the three-phase current of the machine-side converter and the angular velocity of the motor, and a calculation formula thereof is: where N p is the number of pole pairs of the electric machine; L d and L q are the d-axis and q-axis inductances of the generator; I md and I mq are the d-axis and q-axis components of the generator stator current in the rotating reference frame; ψ r is the rated flux linkage value of the generator; and ω m is the mechanical angular frequency of the generator. The d-axis and q-axis components of the stator current of the generator in the rotating coordinate system are obtained by rotating coordinate transformation from the three-phase stator current, and a calculation formula thereof is: where θ r is the rotor position angle of the generator; I ma , I mb , and I mc are the three-phase current values of the generator; A calculation formula of the optimal inertia response coefficient is: wherein J WT is the moment of inertia of the wind turbine; f N is the rated frequency of the power grid; The active power calculation formula of the grid-side converter is: wherein U gd and U gq are the d-axis and q-axis components of the grid three-phase voltage in the grid-side rotating coordinate system; I gd and I gq are the d-axis and q-axis components of the grid-side converter three-phase current in the grid-side rotating coordinate system; The d-axis and q-axis components of the three-phase voltage of the grid in the rotating coordinate system are obtained by rotating coordinate transformation from the three-phase voltage of the grid, and a calculation formula thereof is: wherein U ga , U gb and U gc are the three-phase current values of the generator; The d-axis and q-axis components of the three-phase current of the grid-side converter in the rotating coordinate system are obtained by rotating coordinate transformation from the three-phase current of the grid-side converter, and a calculation formula thereof is: where I ga , I gb , and I gc are the three-phase current values of the grid-side converter.

10. The direct voltage synchronous full power wind turbine control method according to claim 9, characterized in that, The machine-side converter torque-current control module (104) comprises: The torque instruction given by the master is added to the compensation value as the torque reference value of the unit, and the torque reference value and the feedback value are input into the torque controller to obtain the current instruction value; the current instruction value and the feedback value are input into the current controller to obtain the modulation voltage of the machine-side converter, thereby controlling the machine-side converter to work and realizing the inertia response control of the full-power wind turbine generator; The torque-current instruction value of the machine-side converter is obtained by inputting the torque given value and the feedback value into the torque controller, and an expression thereof is: where T e is the actual torque value of the generator; K Pt is the proportional coefficient of the torque control loop; K It is the integral coefficient of the torque control loop.

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