Double-fed gravity energy storage system droop control method and device based on electromagnetic torque

Abstract

The invention discloses a doubly-fed gravity energy storage system droop control method and device based on electromagnetic torque. The method comprises the steps that stator-side three-phase voltage and current, rotor-side three-phase current, an electromagnetic torque actual value and a rotor rotating speed of a doubly-fed motor are collected; giving an electromagnetic torque reference value through a proportional-integral regulator in combination with the rotor speed, and performing droop control in combination with the actual electromagnetic torque value and the rotor speed to obtain a phase reference value and a phase slip; according to the phase reference value and the phase slip frequency, coordinate transformation is carried out on the three-phase voltage and current of the stator side and the three-phase current of the rotor side, and a coordinate transformation result is given; a stator flux linkage is obtained according to a coordinate transformation result, feedforward calculation is carried out, a rotor side voltage adjustment value is given, stator side reactive power is combined, a stator side voltage amplitude reference value is analyzed, a proportional-integral regulator is fused, and a rotor side target voltage reference value is given; and generating a control signal according to the rotor side target voltage reference value to control the doubly-fed motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of gravity energy storage, and in particular relates to a droop control method and device for a double-fed gravity energy storage system based on electromagnetic torque. Background Art

[0002] In the power system, gravity energy storage, as a reliable means of energy storage, provides support for the large-scale consumption of renewable energy.

[0003] At present, most gravity energy storage systems use synchronous motors as generator motors, and realize the conversion of mechanical energy and electrical energy through the synchronous rotation of the motor rotor and the stator magnetic field. Patent CN115714558A discloses a model prediction torque control method for improving the efficiency of gravity energy storage motors, which relates to the field of motor control technology. The voltage vector, rotor position angle and stator current of the motor are input into the prediction model to predict the magnetic flux and torque of the motor at the next moment; the predicted variable value of the motor and the given reference value are subjected to the cost function to screen out the optimal voltage vector to act on the system, and the cost function includes a load angle cost function. The stability performance of the permanent magnet synchronous motor under complex working conditions is improved, thereby improving the efficiency of the gravity energy storage motor control system and improving the practicality of the gravity energy storage system.

[0004] In gravity energy storage, synchronous machines are usually used to convert the gravitational potential energy of heavy objects into electrical energy and transmit it to the load end or the grid end. The speed of the synchronous machine is the speed corresponding to the grid frequency, so that the speed of the weight rising or falling can only maintain a unique value, which makes it difficult to quickly respond to instantaneous changes in load and achieve precise speed regulation. Summary of the invention

[0005] In view of the defects existing in the above-mentioned prior art, the present invention provides a droop control method and device for a doubly-fed gravity energy storage system based on electromagnetic torque, the method comprising: collecting the three-phase voltage on the stator side, the three-phase current on the stator side, the three-phase current on the rotor side, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; using a proportional-integral regulator, in combination with the rotor speed of the doubly-fed motor, providing an electromagnetic torque reference value; based on the electromagnetic torque reference value, in combination with the actual value of the electromagnetic torque and the rotor speed, performing droop control to obtain a phase reference value and a phase slip; according to the phase reference value and the phase slip, The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are transformed into coordinates to give the coordinate transformation result; the flux calculation is performed based on the coordinate transformation result, and the stator flux obtained by the flux calculation is used to perform feedforward calculation to give the rotor side voltage adjustment value; according to the rotor side voltage adjustment value and in combination with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional-integral regulator to give the rotor side target voltage reference value; the rotor side target voltage reference value is subjected to space vector pulse width modulation to generate a control signal to control the rotor side converter in the doubly-fed generator.

[0006] In a first aspect, the present invention provides a droop control method for a double-fed gravity energy storage system based on electromagnetic torque, which specifically comprises the following steps: Collect the three-phase voltage on the stator side, the three-phase current on the stator side, the three-phase current on the rotor side, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; The electromagnetic torque reference value is given by the proportional-integral regulator in combination with the rotor speed of the doubly-fed generator; Based on the electromagnetic torque reference value, combined with the electromagnetic torque actual value and the rotor speed, droop control is performed to obtain a phase reference value and a phase slip; According to the phase reference value and the phase slip, coordinate transformation is performed on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side, and the coordinate transformation result is given; The flux calculation is performed based on the coordinate transformation result, and the stator flux obtained by the flux calculation is combined to perform feedforward calculation to give the voltage adjustment value on the rotor side; According to the rotor side voltage adjustment value, combined with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional integral regulator to give the rotor side target voltage reference value; The rotor side target voltage reference value is subjected to space vector pulse width modulation to generate a control signal to control the rotor side converter in the doubly fed generator.

[0007] Furthermore, the electromagnetic torque reference value is given by the proportional-integral regulator in combination with the rotor speed of the doubly-fed generator, including: According to the rotor speed of the doubly-fed generator and the rotor speed reference value, the change of the rotor speed of the doubly-fed generator is analyzed, and the speed difference between the rotor speed and the rotor speed reference value is given; The proportional-integral regulator is determined by the proportional gain and integral gain of the electromagnetic torque; Combining the proportional-integral regulator and the speed difference, an electromagnetic torque reference value is given.

[0008] Further, based on the electromagnetic torque reference value, combined with the electromagnetic torque actual value and the rotor speed, droop control is performed to obtain a phase reference value, specifically including: According to the electromagnetic torque reference value and the actual electromagnetic torque value, the change of the electromagnetic torque of the doubly-fed motor is analyzed, and the torque difference between the electromagnetic torque reference value and the actual electromagnetic torque value is given; According to the torque difference, combined with the droop coefficient and the frequency setting value, the stator side frequency reference value is given; The stator side frequency reference value is integrated and calculated to obtain the phase reference value.

[0009] Further, the coordinate transformation result includes a stator side voltage component, a stator side current component and a rotor side current component in a two-phase rotating coordinate system; According to the phase reference value and the phase slip, coordinate transformation is performed on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side, and the coordinate transformation results are given, including: The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component and the rotor side current component in the two-phase stationary coordinate system are given; According to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system; According to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system.

[0010] Furthermore, the coordinate transformation is to transform the two-phase / three-phase stationary coordinate system into a two-phase rotating coordinate system.

[0011] Further, the stator side voltage component in the two-phase stationary coordinate system includes a stator side voltage α component and a stator side voltage β component, the stator side current component in the two-phase stationary coordinate system includes a stator side current α component and a stator side current β component, and the rotor side current component in the two-phase stationary coordinate system includes a rotor side current α component and a rotor side current β component; The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component and the rotor side current component in the two-phase stationary coordinate system are given, specifically including: Based on the Clarke transformation matrix, the three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are transformed in the three-phase coordinate system to obtain the corresponding stator side voltage α component, stator side voltage β component, stator side current α component, stator side current β component, rotor side current α component and rotor side current β component.

[0012] Further, the stator side voltage component in the two-phase rotating coordinate system includes a stator side voltage d component and a stator side voltage q component, and the stator side current component in the two-phase rotating coordinate system includes a stator side current d component and a stator side current q component; According to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system, which specifically include: Determining a first Park transformation matrix according to the phase reference value; Based on the first Park transformation matrix, the stator side voltage component and the stator side current component in the two-phase stationary coordinate system are transformed to obtain the corresponding stator side voltage d component, stator side voltage q component, stator side current d component and stator side current q component.

[0013] Further, the rotor side current component in the two-phase rotating coordinate system includes a rotor side current d component and a rotor side current q component; According to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system, which specifically includes: Determine a second Park transformation matrix according to the phase slip; Based on the second Park transformation matrix, coordinate transformation is performed on the rotor side current component in the two-phase stationary coordinate system to obtain the corresponding rotor side current d component and rotor side current q component.

[0014] Furthermore, the flux calculation is performed according to the coordinate transformation result, and the stator flux obtained by the flux calculation is combined to perform feedforward calculation to provide the rotor side voltage adjustment value, which specifically includes: According to the stator side voltage component and the stator side current component in the two-phase stationary coordinate system in the coordinate transformation result, combined with the stator resistance, the stator flux in the two-phase stationary coordinate system is given; According to the first Park transformation matrix, the stator flux in the two-phase stationary coordinate system is combined to obtain the stator flux in the two-phase rotating coordinate system; Based on the stator flux in the two-phase rotating coordinate system, combined with the rotor resistance, rotor leakage inductance, speed slip and mutual inductance, the rotor side voltage adjustment value is obtained.

[0015] Further, the stator flux in the two-phase rotating coordinate system includes a stator flux d component and a stator flux q component, and the rotor side voltage adjustment value includes a rotor side voltage adjustment value d component and a rotor side voltage adjustment value q component; Based on the stator flux in the two-phase rotating coordinate system, combined with the rotor resistance, rotor leakage inductance, speed slip and mutual inductance, the rotor side voltage adjustment value is obtained, which specifically includes: The product of the rotor resistance and the q component of the rotor side current is taken as the first product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current d component is taken as the second product; The product of the speed slip, the leakage inductance ratio and the stator flux d component is taken as the third product, wherein the leakage inductance ratio is the ratio of the mutual inductance to the stator leakage inductance; The product of the rotor resistance and the rotor side current d component is taken as the fourth product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current q component is taken as the fifth product; Add the first product, the second product and the third product to obtain a rotor side voltage adjustment value d component; The fifth product is subtracted from the fourth product to obtain the rotor side voltage adjustment value q component.

[0016] Furthermore, the stator-side reactive power is obtained by multiplying each stator-side line voltage component of the doubly-fed motor by the corresponding stator-side line current component.

[0017] Furthermore, the leakage inductance coefficient is obtained by the stator leakage inductance, the rotor leakage inductance and the mutual inductance.

[0018] Furthermore, according to the rotor side voltage adjustment value, combined with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional integral regulator to give the rotor side target voltage reference value, specifically including: Based on the power difference between the stator side reactive power and the stator side reactive power reference value, combined with the droop coefficient and the voltage amplitude setting value, a stator side voltage amplitude reference value is given; According to the stator side voltage amplitude reference value and the stator side angular frequency reference value, the stator side three-phase voltage in the three-phase stationary coordinate system is given, and the stator side three-phase voltage is transformed into a coordinate to obtain the stator side voltage reference value in the two-phase rotating coordinate system; The voltage difference between the stator side voltage reference value and the stator side voltage component in the two-phase rotating coordinate system is analyzed, and the rotor side current reference value in the two-phase rotating coordinate system is given by combining the proportional integral regulator; A current closed loop is adopted, and the rotor side target voltage reference value is obtained according to the rotor side current reference value and the current difference of the rotor side current component in the two-phase rotating coordinate system, the proportional integral regulator and the rotor side voltage adjustment value are integrated.

[0019] Further, performing space vector pulse width modulation on the rotor side target voltage reference value to generate a control signal to control the rotor side converter in the doubly fed machine specifically includes: Converting the rotor side target voltage reference value from the two-phase rotating coordinate system to the two-phase stationary coordinate system to obtain the rotor side target voltage α component and the rotor side target voltage β component; Analyze the amplitude and phase of the rotor side target voltage according to the rotor side target voltage α component and the rotor side target voltage β component, and determine the sector where the rotor side target voltage is located; Based on the sector where the rotor side target voltage is located, select the effective vector and the zero vector, and give the vector action time; According to the vector action time, a control signal required by the rotor-side converter is generated, and the rotor-side converter in the doubly-fed generator is controlled according to the control signal.

[0020] In a second aspect, the present invention further provides a droop control device for a doubly-fed gravity energy storage system based on electromagnetic torque, which adopts a droop control method for a doubly-fed gravity energy storage system based on electromagnetic torque as described above, comprising: A data acquisition module is used to collect the stator side three-phase voltage, the stator side three-phase current, the rotor side three-phase current, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; The torque determination module is used to provide an electromagnetic torque reference value by combining the rotor speed of the doubly-fed generator through a proportional-integral regulator; A phase determination module, used to perform droop control based on an electromagnetic torque reference value, combined with an actual electromagnetic torque value and a rotor speed, to obtain a phase reference value and a phase slip; A coordinate transformation module is used to perform coordinate transformation on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side according to the phase reference value and the phase slip, and provide a coordinate transformation result; The flux calculation module is used to calculate the flux according to the coordinate transformation result, and to perform feedforward calculation based on the stator flux obtained by the flux calculation to provide the voltage adjustment value on the rotor side; The voltage calculation module is used to analyze the stator side voltage amplitude reference value according to the rotor side voltage adjustment value and the stator side reactive power, integrate the proportional integral regulator, and give the rotor side target voltage reference value; The control module is used to perform space vector pulse width modulation on the rotor side target voltage reference value to generate a control signal to control the rotor side converter in the doubly fed generator.

[0021] The electromagnetic torque-based droop control method and device for a double-fed gravity energy storage system provided by the present invention have at least the following beneficial effects: (1) Through the coordinated control of the stator side and the rotor side of the doubly-fed machine, the rotor side voltage is directly controlled, and the electromagnetic torque reference value is used. Droop control can respond to the rotor speed reference value in time , the mechanical torque of the heavy object and the transformation of the active power consumed at the load end, and make adaptive adjustments to translate the droop curve to maintain the ultimate stability of the gravity energy storage system and improve the grid support capacity of the double-fed gravity energy storage system.

[0022] (2) Introducing the rotor side voltage adjustment value to correct the rotor side voltage can dynamically offset the coupled voltage component, further reduce power fluctuations, and improve the dynamic performance and control accuracy of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a droop control method for a double-fed gravity energy storage system based on electromagnetic torque provided by an embodiment of the present invention; Figure 2A flow chart for providing an electromagnetic torque reference value provided by an embodiment of the present invention; Figure 3 A flow chart for obtaining a phase reference value provided by an embodiment of the present invention; Figure 4 A flow chart for obtaining a phase slip provided by an embodiment of the present invention; Figure 5 A flow chart showing coordinate transformation results provided by an embodiment of the present invention; Figure 6 A flow chart for providing a rotor side voltage adjustment value provided by an embodiment of the present invention; Figure 7 A flow chart of generating a control signal provided by an embodiment of the present invention; Figure 8 A structural block diagram of droop control based on electromagnetic torque provided in an embodiment of the present invention; Fig. 9 A structural block diagram of a droop control device for a double-fed gravity energy storage system based on electromagnetic torque provided in an embodiment of the present invention.

[0024] Among them, 201 is a data acquisition module; 202 is a torque determination module; 203 is a phase determination module; 204 is a coordinate transformation module; 205 is a flux calculation module; 206 is a voltage calculation module; and 207 is a control module. DETAILED DESCRIPTION

[0025] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0027] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0028] As the world pays more attention to clean energy and sustainable development, the development and utilization of renewable energy has become increasingly important.

[0029] Gravity energy storage uses the height difference of objects to achieve energy storage and release. During the charging process, the system converts electrical energy into gravitational potential energy by lifting heavy objects; during the discharge process, the heavy objects descend to drive the generator to generate electricity, converting gravitational potential energy into electrical energy. This energy storage method not only has stable technical performance, long service life and no attenuation, but also has high safety and no pollution. At the same time, gravity energy storage has low requirements for site selection, and there are fewer restrictions on applicable scenarios, and it has the potential for large-scale promotion and application. Especially when combined with new energy projects such as photovoltaic power generation and wind power generation, gravity energy storage can form a comprehensive energy system and improve energy utilization efficiency. In addition, the rotational inertia of gravity energy storage can also provide the power system with system anti-disturbance capability, further improving the stability of the power system.

[0030] In the power system, the grid-connected operation of renewable energy has become a key issue. As an important power electronic device, the doubly-fed motor plays an important role in the grid-connected control of renewable energy. Traditional droop control is a control strategy that has the ability to independently support the grid voltage. It can simulate the droop characteristics of the synchronous generator to generate the phase angle and amplitude of the internal potential, thereby realizing the rapid adjustment of the pulse width modulation (PWM) signal. This control strategy enables the doubly-fed motor to have instantaneous active / reactive response capability when it is connected to the grid, and is no longer limited by the response delay of the measurement link.

[0031] The doubly-fed asynchronous motor can flexibly control the rotor speed, and at the same time, the power regulation fed into the power grid by the gravity energy storage system can be more diverse by changing the rotor speed or the mechanical torque of the weight. However, unlike the synchronous machine, the doubly-fed motor has small damping and mechanical inertia, and its support capacity for the power grid is limited, so a droop control strategy is adopted to simulate the primary frequency modulation characteristics of the synchronous machine. Applying the doubly-fed mechanism network control to the gravity energy storage system can give full play to the advantages of both and further improve the stability and reliability of the power system. This combined application can not only optimize the energy structure and improve the utilization rate and reliability of renewable energy, but also provide strong support and guarantee for the development of new energy and promote the sustainable and healthy development of the new energy industry.

[0032] In order to change the power fed into the grid, it is necessary to change the torque of the weight, e.g. Figure 1 As shown, an embodiment of the present invention provides a droop control method for a double-fed gravity energy storage system based on electromagnetic torque, and the specific steps are as follows: S101: Collecting the stator side three-phase voltage, the stator side three-phase current, the rotor side three-phase current, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor.

[0033] In the embodiment provided by the present invention, the three-phase voltage on the stator side Collected by: First, select a suitable voltage transformer. In this example, an electromagnetic voltage transformer is selected. The rated primary voltage matches the stator side grid voltage, and the secondary side can output a low-voltage standard signal. Connect the selected electromagnetic voltage transformer to the stator side using a three-phase star connection. Install a fuse to protect the secondary side from short circuits, and convert the secondary side voltage signal into an analog quantity through a signal conditioning module for the data acquisition card to read. Use an RC low-pass filter to eliminate high-frequency noise, and use a synchronous sampler to sample, calculate the amplitude, and obtain the effective value of the three-phase voltage, that is, the three-phase voltage on the stator side.

[0034] In the embodiment provided by the present invention, the three-phase current on the stator side Collected by: Similarly, first select a suitable current sensor. In this example, a closed-loop Hall current sensor is selected. The rated current covers the stator rated current and the bandwidth is sufficient to capture high-frequency harmonics. The closed-loop Hall current sensor is connected in series between the stator winding and the grid connection line to ensure independent measurement of the three phases and avoid magnetic field interference. A short-circuit protection resistor is configured on the secondary side of the current sensor to prevent the risk of open circuit high voltage. The current signal output by the sensor is converted into a voltage signal through a precision shunt resistor, and the amplified voltage signal is collected using a synchronous sampler. Finally, the amplified voltage signal is restored to a current signal through a voltage-current conversion circuit to obtain the three-phase current on the stator side.

[0035] In the embodiment provided by the present invention, the three-phase current on the rotor side Collected by: A wide-band Rogowski coil is selected as a sensor to adapt to the frequency change of the rotor current. The wide-band Rogowski coil is connected to the rotor circuit through a slip ring. The contact resistance of the slip ring needs to be <1mΩ to reduce signal attenuation. The Rogowski coil directly outputs mV-level voltage, which is amplified by an instrument amplifier. The amplified signal is restored to the original current signal by an integration circuit to obtain the three-phase current on the rotor side.

[0036] In the embodiment provided by the present invention, the rotor speed Collected by: First, select a suitable encoder. In this example, select an incremental photoelectric encoder. Install the incremental photoelectric encoder on the motor shaft end through a coupling to ensure that the coaxiality error is less than 0.05mm and avoid vibration interference. The incremental photoelectric encoder outputs two orthogonal pulse signals A and B, which are used to calculate the speed and direction. The specific expression is:

[0037] in, is the number of pulses, Z is the number of encoder lines, is the sampling period.

[0038] In the embodiment provided by the present invention, the actual value of the electromagnetic torque Collected by: Select a photoelectric torque sensor to measure the actual value of electromagnetic torque. Install the photoelectric torque sensor on the motor shaft. Collect the torque signal output by the photoelectric torque sensor, amplify and filter the collected torque signal, and then convert the conditioned analog signal into a digital signal. Map the digital signal to the actual torque value through the calibration curve to complete the collection of the actual value of the electromagnetic torque.

[0039] S102: providing an electromagnetic torque reference value through a proportional-integral regulator in combination with the rotor speed of the doubly-fed generator.

[0040] Reference Figure 2 , give the electromagnetic torque reference value, including: According to the rotor speed of the doubly-fed generator and the rotor speed reference value, the change of the rotor speed of the doubly-fed generator is analyzed, and the speed difference between the rotor speed and the rotor speed reference value is given; The proportional-integral regulator is determined by the proportional gain and integral gain of the electromagnetic torque; Combining the proportional-integral regulator and the speed difference, an electromagnetic torque reference value is given.

[0041] In a specific embodiment, the rotor speed As the feedback signal of speed closed loop control, it is controlled by proportional integral regulator. To achieve error-free control of the speed, the transfer function expression of the proportional-integral regulator in the frequency domain is as follows:

[0042] in, is the proportional-integral regulator of electromagnetic torque, S is the complex frequency domain variable in Laplace transform, is the proportional gain of the electromagnetic torque, is the integral gain of electromagnetic torque.

[0043] Speed ​​closed loop output electromagnetic torque reference value , specifically expressed as:

[0044] Where S is the complex frequency domain variable in Laplace transform, is the rotor speed reference value, The rotor speed reference value is the preset speed based on system performance and operating conditions.

[0045] S103: Based on the electromagnetic torque reference value, combined with the electromagnetic torque actual value and the rotor speed, droop control is performed to obtain a phase reference value and a phase slip.

[0046] Reference Figure 3 , get the phase reference value, including: According to the electromagnetic torque reference value and the actual electromagnetic torque value, the change of the electromagnetic torque of the doubly-fed motor is analyzed, and the torque difference between the electromagnetic torque reference value and the actual electromagnetic torque value is given; According to the torque difference, combined with the droop coefficient and the frequency setting value, the stator side frequency reference value is given; The stator side frequency reference value is integrated and calculated to obtain the phase reference value.

[0047] In a specific implementation, the electromagnetic torque reference value As the input of droop control, it is compared with the actual value of electromagnetic torque Combined processing to obtain the stator side frequency reference value , specifically expressed as:

[0048] in, is the stator side frequency reference value, is the preset droop coefficient, is the frequency setting value, is the electromagnetic torque reference value, is the actual value of electromagnetic torque.

[0049] Phase reference value , specifically expressed as:

[0050] in, is the phase reference value, S is the complex frequency domain variable in Laplace transform, is the stator side frequency reference value.

[0051] Reference Figure 4 , and get the phase slip, including: According to the stator side frequency reference value and rotor speed, the change of the doubly-fed generator rotor speed is analyzed and the speed slip is given; Based on the speed slip, the phase slip is given.

[0052] In a specific implementation, the stator side frequency reference value f and the rotor speed Difference, get speed slip , and the speed slip Change to get phase slip , specifically expressed as:

[0053] Where S is the complex frequency domain variable in Laplace transform.

[0054] S104: performing coordinate transformation on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side according to the phase reference value and the phase slip, and providing a coordinate transformation result.

[0055] Among them, the coordinate transformation result includes the stator side voltage component, the stator side current component and the rotor side current component in the two-phase rotating coordinate system. The coordinate transformation is to transform the two-phase / three-phase stationary coordinate system into a two-phase rotating coordinate system. The stator side voltage component in the two-phase stationary coordinate system includes the stator side voltage α component and the stator side voltage β component, the stator side current component in the two-phase stationary coordinate system includes the stator side current α component and the stator side current β component, and the rotor side current component in the two-phase stationary coordinate system includes the rotor side current α component and the rotor side current β component. The stator side voltage component in the two-phase rotating coordinate system includes the stator side voltage d component and the stator side voltage q component, and the stator side current component in the two-phase rotating coordinate system includes the stator side current d component and the stator side current q component. The rotor side current component in the two-phase rotating coordinate system includes the rotor side current d component and the rotor side current q component.

[0056] Reference Figure 5 , giving the coordinate transformation results, including: The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component and the rotor side current component in the two-phase stationary coordinate system are given; According to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system; According to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system.

[0057] Furthermore, the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component, and the rotor side current component in the two-phase stationary coordinate system are given, specifically including: Based on the Clarke transformation matrix, the three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are transformed in the three-phase coordinate system to obtain the corresponding stator side voltage α component, stator side voltage β component, stator side current α component, stator side current β component, rotor side current α component and rotor side current β component.

[0058] In a specific implementation, the stator side voltage component in the two-phase stationary coordinate system is , specifically expressed as:

[0059] in, is the α component of the stator side voltage, is the β component of the stator side voltage, is the three-phase voltage on the stator side in the three-phase coordinate system, is the Clarke transformation matrix.

[0060] Stator side current components in two-phase stationary coordinate system , specifically expressed as:

[0061] in, is the α component of the stator side current, is the β component of the stator side current, is the three-phase current on the stator side in the three-phase coordinate system, is the Clarke transformation matrix.

[0062] Rotor side current components in two-phase stationary coordinate system , specifically expressed as:

[0063]

[0064] in, is the rotor side current α component, is the rotor side current β component, is the three-phase current on the rotor side in the three-phase coordinate system, is the Clarke transformation matrix.

[0065] Further, according to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system, specifically including: Determining a first Park transformation matrix according to the phase reference value; Based on the first Park transformation matrix, the stator side voltage component and the stator side current component in the two-phase stationary coordinate system are transformed to obtain the corresponding stator side voltage d component, stator side voltage q component, stator side current d component and stator side current q component.

[0066] In a specific implementation, the first Park transformation matrix , specifically expressed as:

[0067] in, is the phase reference value. , construct the first Park transformation matrix , transform the stator side voltage component and the stator side current component from the two-phase stationary coordinate system to the two-phase rotating coordinate system.

[0068] Stator side voltage components in two-phase rotating coordinate system , specifically expressed as:

[0069] in, is the stator side voltage d component, is the q component of the stator side voltage.

[0070] Stator side current components in two-phase rotating coordinate system , specifically expressed as:

[0071] in, is the stator side current d component, is the q component of the stator side current.

[0072] Further, according to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system, which specifically includes: Determine a second Park transformation matrix according to the phase slip; Based on the second Park transformation matrix, coordinate transformation is performed on the rotor side current component in the two-phase stationary coordinate system to obtain the corresponding rotor side current d component and rotor side current q component.

[0073] In a specific implementation, the second Park transformation matrix , specifically expressed as:

[0074] in, is the phase slip. , construct the second Park transformation matrix , transform the rotor side voltage component and the rotor side current component from the two-phase stationary coordinate system to the two-phase rotating coordinate system.

[0075] Rotor side current components in two-phase rotating coordinate system , specifically expressed as:

[0076] in, is the rotor side current d component, is the q component of the rotor side current.

[0077] S105: Calculate the flux according to the coordinate transformation result, perform feedforward calculation based on the stator flux obtained by the flux calculation, and provide a rotor side voltage adjustment value.

[0078] Among them, the stator flux in the two-phase rotating coordinate system includes a stator flux d component and a stator flux q component, the stator flux in the two-phase stationary coordinate system includes a stator flux α component and a stator flux β component, and the rotor side voltage adjustment value includes a rotor side voltage adjustment value d component and a rotor side voltage adjustment value q component.

[0079] Reference Figure 6 , give the rotor side voltage adjustment value, including: According to the stator side voltage component and the stator side current component in the two-phase stationary coordinate system in the coordinate transformation result, combined with the stator resistance, the stator flux in the two-phase stationary coordinate system is given; According to the first Park transformation matrix, the stator flux in the two-phase stationary coordinate system is combined to obtain the stator flux in the two-phase rotating coordinate system; Based on the stator flux in the two-phase rotating coordinate system, combined with the rotor resistance, rotor leakage inductance, speed slip and mutual inductance, the rotor side voltage adjustment value is obtained.

[0080] In a specific implementation, the stator flux in a two-phase stationary coordinate system , specifically expressed as:

[0081] in, is the stator flux α component, is the stator flux β component, is the stator side voltage component in the two-phase stationary coordinate system, is the stator side current component in the two-phase stationary coordinate system, is the stator resistance, and S is the complex frequency domain variable in Laplace transform.

[0082] Stator flux in two-phase rotating coordinate system , specifically expressed as:

[0083] Through the first Park transformation matrix, the stator flux in the two-phase stationary coordinate system is converted to the two-phase rotating coordinate system, and the stator flux in the two-phase rotating coordinate system is obtained. .

[0084] Further, the rotor side voltage adjustment value is obtained, which specifically includes: The product of the rotor resistance and the q component of the rotor side current is taken as the first product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current d component is taken as the second product; The product of the speed slip, the leakage inductance ratio and the stator flux d component is taken as the third product, wherein the leakage inductance ratio is the ratio of the mutual inductance to the stator leakage inductance; The product of the rotor resistance and the rotor side current d component is taken as the fourth product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current q component is taken as the fifth product, wherein the leakage inductance coefficient is obtained by the stator leakage inductance, the rotor leakage inductance and the mutual inductance; Add the first product, the second product and the third product to obtain a rotor side voltage adjustment value d component; The fifth product is subtracted from the fourth product to obtain the rotor side voltage adjustment value q component.

[0085] In a specific implementation, the rotor side voltage adjustment value , specifically expressed as:

[0086] in, is the rotor side voltage adjustment value d component, is the rotor side voltage adjustment value q component, is the rotor resistance, is the rotor side current q component, is the speed slip, is the leakage inductance coefficient, is the rotor leakage inductance, is the rotor side current d component, For mutual induction, is the stator leakage inductance, is the stator flux d component.

[0087] S106: According to the rotor side voltage adjustment value and in combination with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into a proportional integral regulator to provide a rotor side target voltage reference value.

[0088] The stator side reactive power is obtained by multiplying each stator side line voltage component of the doubly fed generator by the corresponding stator side line current component. , specifically expressed as:

[0089] in, They are the stator side line voltage components under three-phase voltage coordinates, They are respectively the stator side line current components corresponding to the stator side line voltage components under the three-phase voltage coordinates.

[0090] It can be understood that line voltage refers to the voltage between any two end wires (live wires) in a three-phase circuit. In a symmetrical three-phase circuit, the voltage of each phase is equal and the phase difference is 120°. Line current refers to the current flowing between any two end wires (live wires) in a three-phase circuit. In a symmetrical three-phase circuit, the current of each phase is equal and the phase difference is 120°.

[0091] Furthermore, according to the rotor side voltage adjustment value, combined with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional integral regulator to give the rotor side target voltage reference value, specifically including: Based on the power difference between the stator side reactive power and the stator side reactive power reference value, combined with the droop coefficient and the voltage amplitude setting value, a stator side voltage amplitude reference value is given; According to the stator side voltage amplitude reference value and the stator side angular frequency reference value, the stator side three-phase voltage in the three-phase stationary coordinate system is given, and the stator side three-phase voltage is transformed into a coordinate to obtain the stator side voltage reference value in the two-phase rotating coordinate system; The voltage difference between the stator side voltage reference value and the stator side voltage component in the two-phase rotating coordinate system is analyzed, and the rotor side current reference value in the two-phase rotating coordinate system is given by combining the proportional integral regulator; A current closed loop is adopted, and the rotor side target voltage reference value is obtained according to the rotor side current reference value and the current difference of the rotor side current component in the two-phase rotating coordinate system, the proportional integral regulator and the rotor side voltage adjustment value are integrated.

[0092] The stator side reactive power As input in droop control, the stator side reactive power reference The difference between the droop coefficient and Add the voltage amplitude setting value The stator side voltage amplitude reference value E is obtained, which is specifically expressed as:

[0093] in, is the stator side reactive power, is the stator side reactive power reference value, is the droop coefficient, Set a value for the voltage amplitude.

[0094] In a specific implementation manner, the stator side voltage amplitude reference value E and the stator side angular frequency reference value The three-phase voltage on the synthesized stator side is specifically expressed as:

[0095] in, They are the voltages of the three-phase voltage on the stator side at both ends of each phase winding of the power supply or load.

[0096] The three-phase voltage on the stator side is transformed from the three-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage reference value in the two-phase rotating coordinate system. , specifically expressed as:

[0097] in, is the stator side voltage reference value in the two-phase stationary coordinate system, is the α component of the stator side voltage reference value, is the stator side voltage reference value β component, is the stator side voltage reference value d component, is the q component of the stator side voltage reference value, is the first Park transformation matrix, is the Clarke transformation matrix.

[0098] Will As the reference value of the voltage outer loop input, the stator side voltage component in the two-phase rotating coordinate system As the feedback value, the difference between the two is adjusted by the proportional integral regulator. Processing, output rotor side current reference value in two-phase rotating coordinate system , specifically expressed as:

[0099] in, is the rotor side current reference value d component, is the rotor side current reference value q component, is the proportional-integral regulator of the rotor side voltage, S is the complex frequency domain variable in Laplace transform, is the proportional gain of the rotor side voltage, is the integral gain of the rotor side voltage.

[0100] In the current closed-loop control, the rotor side current reference value The rotor side current component The difference passes through the proportional integral regulator Processing, plus the rotor side voltage adjustment value That is, the rotor side target voltage reference value in the two-phase rotating coordinate system is obtained, which is specifically expressed as:

[0101] in, is the rotor side target voltage reference value d component, is the q component of the rotor side target voltage reference value, is the proportional-integral regulator of the rotor side current, S is the complex frequency domain variable in the Laplace transform, is the proportional gain of the rotor side current, is the integral gain of the rotor side current.

[0102] S107: Perform space vector pulse width modulation on the rotor-side target voltage reference value to generate a control signal to control the rotor-side converter in the doubly-fed generator.

[0103] Reference Figure 7 , specifically including: Converting the rotor side target voltage reference value from the two-phase rotating coordinate system to the two-phase stationary coordinate system to obtain the rotor side target voltage α component and the rotor side target voltage β component; Analyze the amplitude and phase of the rotor side target voltage according to the rotor side target voltage α component and the rotor side target voltage β component, and determine the sector where the rotor side target voltage is located; wherein the rotor side target voltage includes the rotor side target voltage α component and the rotor side target voltage β component; Based on the sector where the rotor side target voltage is located, select the effective vector and the zero vector, and give the vector action time; According to the vector action time, a control signal required by the rotor-side converter is generated, and the rotor-side converter in the doubly-fed generator is controlled according to the control signal.

[0104] Space vector pulse width modulation (SVPWM) is a modulation technology for three-phase inverters. It is mainly used to control the output voltage vector of the inverter to achieve high-efficiency and low-harmonic motor drive.

[0105] In a specific implementation, the rotor side target voltage reference value is first converted from the two-phase rotating coordinate system to the two-phase stationary coordinate system to obtain the rotor side target voltage α component and the rotor side target voltage β component . Then, according to the amplitude and phase of the rotor-side target voltage α component and the rotor-side target voltage β component, the sector in which they are located is determined. According to the sector in which the rotor-side target voltage is located, two adjacent effective vectors and one zero vector are selected and the vector action time is calculated. According to the vector action time, the duration of each switching state is allocated, and according to the allocated switching state, the corresponding control signal is generated to control the switching action of the inverter.

[0106] Vector action time, specifically expressed as:

[0107] in, is the total switching cycle, i.e. the total vector action time, and is the vector action time of two adjacent effective vectors, is the vector action time of the zero vector, is the amplitude of the target voltage on the rotor side, is the DC bus voltage, is the switching frequency.

[0108] Reference Figure 8 In the control process of the electromagnetic torque-based double-fed gravity energy storage system droop control method provided by the embodiment of the present invention, the electromagnetic torque-frequency droop control replaces the traditional active power-frequency droop control. The electromagnetic torque-frequency droop control utilizes the electromagnetic torque reference value output by the rotor closed loop. , and the actual value of electromagnetic torque , and frequency setting value Let’s build the sag curve together:

[0109] Different from the active power reference value in active power-frequency droop control Once set, it cannot be changed, but the electromagnetic torque reference value is used When droop control is performed, when the rotor speed reference value When the load is changing, when the mechanical torque of the weight is changing, when the active power consumed by the load is changing, They can make adaptive adjustments and translate the droop curve to maintain the ultimate stability of the gravity energy storage system. By constructing an adaptive electromagnetic torque-frequency droop curve, the speed control and droop control are combined to realize an adaptive droop control method, thereby improving the supporting capacity of the power grid of the double-fed gravity energy storage system.

[0110] In a specific example, an electromagnetic torque-frequency droop control model of a doubly-fed gravity energy storage system is built in Simulink. When the load and weight block torque remain unchanged, the rotor speed of the doubly-fed motor is controlled: It can be seen that when the mechanical torque of the weight block input to the doubly-fed motor in the gravity energy storage is constant, the adaptive translation adjustment of the droop curve can be achieved by changing the rotor speed. When the rotor speed is stable, the electromagnetic torque reference value is -0.6; when the rotor speed rises, the electromagnetic torque is greater than -0.6; when the rotor speed decreases, the electromagnetic torque is less than -0.6. The error between the actual value of the electromagnetic torque and the reference value will be directly reflected in the frequency of the droop control output. Different electromagnetic torques and their corresponding frequencies are extracted, and curve fitting is performed. The curve can reflect that the droop characteristic constructed by the electromagnetic torque-frequency has an electromagnetic torque reference value. Adaptive translation capability. Among them, Simulink is a graphical programming environment based on MATLAB for multi-domain simulation and model design.

[0111] By building an electromagnetic torque-frequency droop control model of a doubly-fed gravity energy storage system in Simulink for simulation verification, we can learn that in the gravity energy storage system, as the weight blocks are changed, the power sent to the load is adjusted so that it can cope with the load changes well. During the simulation process, the mechanical torque is matched with the load power, that is, the energy storage end will put in the corresponding weight blocks according to the power required by the load end.

[0112] When the circuit working condition suddenly changes, the electromagnetic torque reference value fluctuates but can eventually stabilize at the corresponding mechanical torque value, so that in steady state, the error between the electromagnetic torque reference value and the actual electromagnetic torque value is almost 0. Through droop control, the frequency can be stabilized at 50Hz with almost no deviation. This also reflects the electromagnetic torque reference value. Through the speed closed-loop output, it can be adjusted autonomously to achieve the translation of the droop curve to achieve no offset in the steady state of frequency adjustment. At the same time, except for the speed fluctuation caused by sudden changes in working conditions, the speed can also be well maintained at the set value in the steady state.

[0113] Reference Fig. 9 The embodiment of the present invention provides a droop control device for a double-fed gravity energy storage system based on electromagnetic torque, comprising: The data acquisition module 201 is used to collect the three-phase voltage on the stator side, the three-phase current on the stator side, the three-phase current on the rotor side, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; The torque determination module 202 is used to provide an electromagnetic torque reference value by combining the rotor speed of the doubly-fed generator through a proportional-integral regulator; A phase determination module 203 is used to perform droop control based on the electromagnetic torque reference value, combined with the electromagnetic torque actual value and the rotor speed to obtain a phase reference value and a phase slip; A coordinate transformation module 204 is used to perform coordinate transformation on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side according to the phase reference value and the phase slip, and provide a coordinate transformation result; The flux calculation module 205 is used to perform flux calculation according to the coordinate transformation result, and perform feedforward calculation based on the stator flux obtained by the flux calculation to provide a rotor side voltage adjustment value; The voltage calculation module 206 is used to analyze the stator side voltage amplitude reference value according to the rotor side voltage adjustment value and the stator side reactive power, integrate the proportional integral regulator, and provide the rotor side target voltage reference value; The control module 207 is used to perform space vector pulse width modulation on the rotor-side target voltage reference value to generate a control signal to control the rotor-side converter in the doubly-fed generator.

[0114] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described module can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0115] It should be noted that the computer-readable medium mentioned above in the present disclosure may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or device. In the present disclosure, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer readable signal medium may also be any computer readable medium other than a computer readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the computer readable medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.

[0116] The computer-readable medium may be included in the electronic device, or may exist independently without being incorporated into the electronic device.

[0117] Computer program code for performing the operations of the present disclosure may be written in one or more programming languages, or a combination thereof, including object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0118] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0119] The units involved in the embodiments of the present disclosure may be implemented by software or hardware, wherein the name of a unit does not limit the unit itself in some cases.

[0120] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A droop control method for a double-fed gravity energy storage system based on electromagnetic torque, characterized in that: include: Collect the three-phase voltage on the stator side, the three-phase current on the stator side, the three-phase current on the rotor side, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; The electromagnetic torque reference value is given by the proportional-integral regulator in combination with the rotor speed of the doubly-fed generator; Based on the electromagnetic torque reference value, combined with the electromagnetic torque actual value and the rotor speed, droop control is performed to obtain a phase reference value and a phase slip; According to the phase reference value and the phase slip, coordinate transformation is performed on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side, and the coordinate transformation result is given; The flux calculation is performed based on the coordinate transformation result, and the stator flux obtained by the flux calculation is combined to perform feedforward calculation to give the voltage adjustment value on the rotor side; According to the rotor side voltage adjustment value, combined with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional integral regulator to give the rotor side target voltage reference value; The rotor side target voltage reference value is subjected to space vector pulse width modulation to generate a control signal to control the rotor side converter in the doubly fed generator.

2. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: Through the proportional-integral regulator, combined with the rotor speed of the doubly-fed generator, the electromagnetic torque reference value is given, including: According to the rotor speed of the doubly-fed generator and the rotor speed reference value, the change of the rotor speed of the doubly-fed generator is analyzed, and the speed difference between the rotor speed and the rotor speed reference value is given; The proportional-integral regulator is determined by the proportional gain and integral gain of the electromagnetic torque; Combining the proportional-integral regulator and the speed difference, an electromagnetic torque reference value is given.

3. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: Based on the electromagnetic torque reference value, combined with the actual electromagnetic torque value and the rotor speed, droop control is performed to obtain the phase reference value, specifically including: According to the electromagnetic torque reference value and the actual electromagnetic torque value, the change of the electromagnetic torque of the doubly-fed motor is analyzed, and the torque difference between the electromagnetic torque reference value and the actual electromagnetic torque value is given; According to the torque difference, combined with the droop coefficient and the frequency setting value, the stator side frequency reference value is given; The stator side frequency reference value is integrated and calculated to obtain the phase reference value.

4. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: The coordinate transformation result includes the stator side voltage component, the stator side current component and the rotor side current component in the two-phase rotating coordinate system; According to the phase reference value and the phase slip, coordinate transformation is performed on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side, and the coordinate transformation results are given, including: The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component and the rotor side current component in the two-phase stationary coordinate system are given; According to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system; According to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system.

5. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1 or 4, characterized in that: The coordinate transformation is to transform the two-phase / three-phase stationary coordinate system into a two-phase rotating coordinate system.

6. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque as claimed in claim 4, characterized in that: The stator side voltage component in the two-phase stationary coordinate system includes the stator side voltage α component and the stator side voltage β component, the stator side current component in the two-phase stationary coordinate system includes the stator side current α component and the stator side current β component, and the rotor side current component in the two-phase stationary coordinate system includes the rotor side current α component and the rotor side current β component; The three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are converted from the three-phase coordinate system to the two-phase stationary coordinate system, and the stator side voltage component, the stator side current component and the rotor side current component in the two-phase stationary coordinate system are given, specifically including: Based on the Clarke transformation matrix, the three-phase voltage on the stator side, the three-phase current on the stator side and the three-phase current on the rotor side are transformed in the three-phase coordinate system to obtain the corresponding stator side voltage α component, stator side voltage β component, stator side current α component, stator side current β component, rotor side current α component and rotor side current β component.

7. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque as claimed in claim 4, characterized in that: The stator side voltage component in the two-phase rotating coordinate system includes a stator side voltage d component and a stator side voltage q component, and the stator side current component in the two-phase rotating coordinate system includes a stator side current d component and a stator side current q component; According to the phase reference value, the stator side voltage component and the stator side current component are converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the stator side voltage component and the stator side current component in the two-phase rotating coordinate system, which specifically include: Determining a first Park transformation matrix according to the phase reference value; Based on the first Park transformation matrix, the stator side voltage component and the stator side current component in the two-phase stationary coordinate system are transformed to obtain the corresponding stator side voltage d component, stator side voltage q component, stator side current d component and stator side current q component.

8. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque as claimed in claim 4, characterized in that: The rotor side current component in the two-phase rotating coordinate system includes the rotor side current d component and the rotor side current q component; According to the phase slip, the rotor side current component is converted from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the rotor side current component in the two-phase rotating coordinate system, which specifically includes: Determine a second Park transformation matrix according to the phase slip; Based on the second Park transformation matrix, coordinate transformation is performed on the rotor side current component in the two-phase stationary coordinate system to obtain the corresponding rotor side current d component and rotor side current q component.

9. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: The flux calculation is performed based on the coordinate transformation results. Combined with the stator flux obtained by the flux calculation, the feedforward calculation is performed to give the rotor side voltage adjustment value, including: According to the stator side voltage component and the stator side current component in the two-phase stationary coordinate system in the coordinate transformation result, combined with the stator resistance, the stator flux in the two-phase stationary coordinate system is given; According to the first Park transformation matrix, the stator flux in the two-phase stationary coordinate system is combined to obtain the stator flux in the two-phase rotating coordinate system; Based on the stator flux in the two-phase rotating coordinate system, combined with the rotor resistance, rotor leakage inductance, speed slip and mutual inductance, the rotor side voltage adjustment value is obtained.

10. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 9, characterized in that: The stator flux in the two-phase rotating coordinate system includes a stator flux d component and a stator flux q component, and the rotor side voltage adjustment value includes a rotor side voltage adjustment value d component and a rotor side voltage adjustment value q component; Based on the stator flux in the two-phase rotating coordinate system, combined with the rotor resistance, rotor leakage inductance, speed slip and mutual inductance, the rotor side voltage adjustment value is obtained, which specifically includes: The product of the rotor resistance and the q component of the rotor side current is taken as the first product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current d component is taken as the second product; The product of the speed slip, the leakage inductance ratio and the stator flux d component is taken as the third product, wherein the leakage inductance ratio is the ratio of the mutual inductance to the stator leakage inductance; The product of the rotor resistance and the rotor side current d component is taken as the fourth product; The product of the speed slip, the leakage inductance coefficient, the rotor leakage inductance and the rotor side current q component is taken as the fifth product; Add the first product, the second product and the third product to obtain a rotor side voltage adjustment value d component; The fifth product is subtracted from the fourth product to obtain the rotor side voltage adjustment value q component.

11. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: The stator-side reactive power is obtained by multiplying each stator-side line voltage component of the doubly-fed generator by the corresponding stator-side line current component.

12. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 11, characterized in that: The leakage inductance coefficient is obtained by stator leakage inductance, rotor leakage inductance and mutual inductance.

13. The droop control method of a double-fed gravity energy storage system based on electromagnetic torque according to claim 1 or 11, characterized in that: According to the rotor side voltage adjustment value, combined with the stator side reactive power, the stator side voltage amplitude reference value is analyzed and integrated into the proportional integral regulator to give the rotor side target voltage reference value, including: Based on the power difference between the stator side reactive power and the stator side reactive power reference value, combined with the droop coefficient and the voltage amplitude setting value, a stator side voltage amplitude reference value is given; According to the stator side voltage amplitude reference value and the stator side angular frequency reference value, the stator side three-phase voltage in the three-phase stationary coordinate system is given, and the stator side three-phase voltage is transformed into a coordinate to obtain the stator side voltage reference value in the two-phase rotating coordinate system; The voltage difference between the stator side voltage reference value and the stator side voltage component in the two-phase rotating coordinate system is analyzed, and the rotor side current reference value in the two-phase rotating coordinate system is given by combining the proportional integral regulator; A current closed loop is adopted, and the rotor side target voltage reference value is obtained according to the rotor side current reference value and the current difference of the rotor side current component in the two-phase rotating coordinate system, the proportional integral regulator and the rotor side voltage adjustment value are integrated.

14. The droop control method of the double-fed gravity energy storage system based on electromagnetic torque according to claim 1, characterized in that: Performing space vector pulse width modulation on the rotor side target voltage reference value to generate a control signal to control the rotor side converter in the doubly fed generator, specifically including: Converting the rotor side target voltage reference value from the two-phase rotating coordinate system to the two-phase stationary coordinate system to obtain the rotor side target voltage α component and the rotor side target voltage β component; Analyze the amplitude and phase of the rotor side target voltage according to the rotor side target voltage α component and the rotor side target voltage β component, and determine the sector where the rotor side target voltage is located; Based on the sector where the rotor side target voltage is located, select the effective vector and the zero vector, and give the vector action time; According to the vector action time, a control signal required by the rotor-side converter is generated, and the rotor-side converter in the doubly-fed generator is controlled according to the control signal.

15. A droop control device for a double-fed gravity energy storage system based on electromagnetic torque, characterized in that: The droop control method of the double-fed gravity energy storage system based on electromagnetic torque as claimed in any one of claims 1 to 14 comprises: A data acquisition module is used to collect the stator side three-phase voltage, the stator side three-phase current, the rotor side three-phase current, the actual value of the electromagnetic torque and the rotor speed of the doubly-fed motor; The torque determination module is used to provide an electromagnetic torque reference value by combining the rotor speed of the doubly-fed generator through a proportional-integral regulator; A phase determination module, used to perform droop control based on an electromagnetic torque reference value, combined with an actual electromagnetic torque value and a rotor speed, to obtain a phase reference value and a phase slip; A coordinate transformation module is used to perform coordinate transformation on the three-phase voltage on the stator side, the three-phase current on the stator side, and the three-phase current on the rotor side according to the phase reference value and the phase slip, and provide a coordinate transformation result; The flux calculation module is used to calculate the flux according to the coordinate transformation result, and to perform feedforward calculation based on the stator flux obtained by the flux calculation to provide the voltage adjustment value on the rotor side; The voltage calculation module is used to analyze the stator side voltage amplitude reference value according to the rotor side voltage adjustment value and the stator side reactive power, integrate the proportional integral regulator, and give the rotor side target voltage reference value; The control module is used to perform space vector pulse width modulation on the rotor side target voltage reference value to generate a control signal to control the rotor side converter in the doubly fed generator.

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