Grid connection starting method and grid connection starting system of gravity energy storage device

Abstract

The invention relates to a starting grid-connected method and a starting grid-connected system of a gravity energy storage device, and the starting grid-connected method of the gravity energy storage device uses an asynchronous starting motor and a frequency converter to replace a large-capacity frequency conversion starting device, thereby reducing the investment cost of gravity energy storage technology engineering construction. The output current of the frequency converter can be effectively adjusted through the three-phase current of the asynchronous starting motor and the feedback rotating speed of the rotor in the asynchronous starting motor, so that the rotating speed of the asynchronous starting motor is effectively adjusted, and the gravity energy storage device is controlled to start grid connection based on the adjusted rotating speed; therefore, safe and stable starting and grid-connected operation of the gravity energy storage system are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and particularly to a starting and grid-connection method and a starting and grid-connection system for a gravity energy storage device. Background Art

[0002] In the context of the construction of a new power system, the development and application of energy storage technologies can effectively promote the consumption of renewable energy power generation and improve the peak shaving and valley filling capabilities of the power grid. The power of a gravity energy storage system based on solid media can reach the megawatt level. When the gravity energy storage system adopts the direct grid-connection method of a synchronous motor, the driving / generating synchronous motor used is a high-voltage large-capacity electrically excited synchronous motor. The smooth starting and safe grid connection of the large-capacity electrically excited synchronous motor are the keys to the safe and stable operation of the gravity energy storage system. The starting of the large-capacity electrically excited synchronous motor usually adopts variable-frequency starting. This starting method requires the configuration of an independent large-capacity variable-frequency starting device, which increases the investment cost of the gravity energy storage technology project construction.

[0003] Therefore, for a large-capacity gravity energy storage system, it is urgent to study a starting and grid-connection device and method for a large-capacity synchronous motor with good starting performance and low investment cost to ensure the smooth starting and grid-connection operation of the gravity energy storage system. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a starting and grid-connection method for a gravity energy storage device. The starting and grid-connection method includes:

[0005] When the grid-connection clutch in the starting and grid-connection system is closed, obtain the three-phase current of the asynchronous starting motor in the starting and grid-connection system and the feedback speed of the rotor in the asynchronous starting motor. The starting and grid-connection system includes a series-connected grid-connection clutch, an asynchronous starting motor, and an inverter. The starting and grid-connection system is connected to the gravity energy storage device through the grid-connection clutch, and the inverter is also connected to the power grid;

[0006] Based on the three-phase current and the feedback speed, adjust the speed of the asynchronous starting motor through the inverter;

[0007] Based on the adjusted speed, control the gravity energy storage device to start and connect to the grid.

[0008] Optionally, the adjusting the speed of the asynchronous starting motor through the inverter based on the three-phase current and the feedback speed includes:

[0009] Based on a preset rotor magnetic flux, a preset speed, and the feedback speed, obtain a spatial angle;

[0010] Based on the spatial angle, the three-phase current is transformed by using Clarke transformation and Park transformation to obtain the excitation current and torque current of the rotor;

[0011] Based on the excitation current, the torque current and the space angle, the preset rotor flux, the preset speed and the feedback speed are processed by using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component;

[0012] Based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starter motor is adjusted by the frequency converter.

[0013] Optionally, obtaining the spatial angle based on a preset rotor flux, a preset speed and the feedback speed includes:

[0014] Calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference;

[0015] Using a speed regulator, the standby speed difference is adjusted to obtain a reference torque current;

[0016] A spatial angle is calculated based on the reference torque current and the feedback rotation speed.

[0017] Optionally, the spatial angle satisfies the following formula:

[0018]

[0019] Among them, θ e is the spatial angle, is the angular velocity of the Park transform, ω r is the feedback speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the coaxial equivalent windings of the stator and rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor flux on the direct axis.

[0020] Optionally, the preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator and a stator current excitation component regulator;

[0021] The method of processing the preset rotor flux, the preset speed and the feedback speed based on the excitation current, the torque current and the space angle using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component includes:

[0022] Based on the preset rotational speed and the feedback rotational speed, use the rotational speed regulator to obtain a reference torque current;

[0023] Use the magnetic flux current conversion to convert the preset rotor magnetic flux to obtain a reference excitation current;

[0024] Based on the reference torque current and the torque current, use the stator current torque component regulator to obtain a torque voltage;

[0025] Based on the reference excitation current and the excitation current, use the stator current excitation component regulator to obtain an excitation voltage;

[0026] Based on the torque voltage, the excitation voltage, and the spatial angle, use the Park inverse transformation to obtain the α-axis voltage component and the β-axis voltage component.

[0027] Optionally, the step of obtaining the α-axis voltage component and the β-axis voltage component based on the torque voltage, the excitation voltage, and the spatial angle by using the Park inverse transformation includes:

[0028] Find the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage;

[0029] Find the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage;

[0030] Based on the spatial angle, use the Park inverse transformation to transform the reference torque voltage and the reference excitation voltage to obtain the α-axis voltage component and the β-axis voltage component.

[0031] Optionally, the step of controlling the gravity energy storage device to start and connect to the grid based on the adjusted rotational speed includes:

[0032] When the adjusted rotational speed reaches a preset rotational speed threshold, based on the grid voltage and the synchronous motor terminal voltage, adjust the rotational speed of the asynchronous starting motor to determine the voltage amplitude difference, frequency difference, and phase difference on both sides of the grid connection contactor in the starting grid connection system;

[0033] Based on the voltage amplitude difference, the frequency difference, and the phase difference, control the gravity energy storage device to start and connect to the grid.

[0034] Optionally, the step of adjusting the rotational speed of the asynchronous starting motor based on the grid voltage and the synchronous motor terminal voltage to determine the voltage amplitude difference, frequency difference, and phase difference on both sides of the grid connection contactor in the starting grid connection system includes:

[0035] Based on the grid voltage and the synchronous motor terminal voltage, obtain the quadrature axis component of the synchronous motor terminal voltage;

[0036] Subtract the quadrature axis component from the quadrature axis reference voltage to obtain a standby voltage difference;

[0037] Use a proportional-integral controller to process the standby voltage difference to obtain a rotational speed correction amount;

[0038] Based on the rotational speed correction amount, adjust the rotational speed of the induction starting motor, and determine the voltage amplitude difference, frequency difference, and phase difference on both sides of the grid-connected contactor in the starting grid-connection system.

[0039] Optionally, the controlling the gravity energy storage device to start grid connection based on the voltage amplitude difference, the frequency difference, and the phase difference includes:

[0040] When the voltage amplitude difference is less than or equal to a preset voltage amplitude difference, the frequency difference is less than or equal to a preset frequency difference, and the phase difference is less than or equal to a preset frequency difference, control the gravity energy storage device to start grid connection.

[0041] Based on the same inventive concept, the present invention also provides a starting grid-connection system for a gravity energy storage device, and the starting grid-connection system includes: a grid-connected clutch, an induction starting motor, an inverter, and a controller;

[0042] The grid-connected clutch, the induction starting motor, and the inverter are connected in series in sequence;

[0043] The starting grid-connection system is connected to the gravity energy storage device through the grid-connected clutch, and the inverter is also connected to the power grid;

[0044] The controller is connected to the induction starting motor and the inverter;

[0045] The controller is configured to, when the grid-connected clutch is closed, obtain the three-phase current of the induction starting motor and the feedback rotational speed of the rotor in the induction starting motor; based on the three-phase current and the feedback rotational speed, adjust the rotational speed of the induction starting motor through the inverter; and based on the adjusted rotational speed, control the gravity energy storage device to start grid connection.

[0046] Optionally, the controller is specifically configured to:

[0047] Based on a preset rotor flux linkage, a preset rotational speed, and the feedback rotational speed, obtain a spatial angle;

[0048] Based on the spatial angle, use the Clarke transformation and the Park transformation to perform coordinate transformation on the three-phase current to obtain the field current and torque current of the rotor;

[0049] Based on the excitation current, the torque current and the space angle, the preset rotor flux, the preset speed and the feedback speed are processed by using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component;

[0050] Based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starter motor is adjusted by the frequency converter.

[0051] Optionally, the controller is specifically used to:

[0052] Calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference;

[0053] Using a speed regulator, the standby speed difference is adjusted to obtain a reference torque current;

[0054] A spatial angle is calculated based on the reference torque current and the feedback rotation speed.

[0055] Optionally, the spatial angle satisfies the following formula:

[0056]

[0057] Among them, θ e is the spatial angle, is the angular velocity of the Park transform, ω r is the feedback speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the coaxial equivalent windings of the stator and rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor flux on the direct axis.

[0058] Optionally, the preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator and a stator current excitation component regulator;

[0059] The controller is specifically used for:

[0060] Based on the preset speed and the feedback speed, using the speed regulator, a reference torque current is obtained;

[0061] Using the flux current conversion, the preset rotor flux is converted to obtain a reference excitation current;

[0062] Based on the reference torque current and the torque current, using the stator current torque component regulator, a torque voltage is obtained;

[0063] Based on the reference excitation current and the excitation current, using the stator current excitation component regulator, an excitation voltage is obtained;

[0064] Based on the torque voltage, the excitation voltage and the space angle, an α-axis voltage component and a β-axis voltage component are obtained by using an inverse Park transform.

[0065] Optionally, the controller is specifically used to:

[0066] Calculating the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage;

[0067] Calculating the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage;

[0068] Based on the spatial angle, the reference torque voltage and the reference excitation voltage are transformed by using inverse Park transformation to obtain an α-axis voltage component and a β-axis voltage component.

[0069] Optionally, the controller is specifically used to:

[0070] When the adjusted speed reaches a preset speed threshold, the speed of the asynchronous starting motor is adjusted based on the grid voltage and the terminal voltage of the synchronous motor, and the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system are determined;

[0071] Based on the voltage amplitude difference, the frequency difference and the phase difference, the gravity energy storage device is controlled to start and connect to the grid.

[0072] Optionally, the controller is specifically used to:

[0073] Based on the grid voltage and the synchronous motor terminal voltage, a quadrature axis component of the synchronous motor terminal voltage is obtained;

[0074] Calculating the difference between the quadrature-axis component and the quadrature-axis reference voltage to obtain a standby voltage difference;

[0075] Using a proportional-integral controller, the standby voltage difference is processed to obtain a speed correction value;

[0076] Based on the speed correction amount, the speed of the asynchronous starting motor is adjusted to determine the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system.

[0077] Optionally, the controller is specifically used to:

[0078] When the voltage amplitude difference is less than or equal to the preset voltage amplitude difference, the frequency difference is less than or equal to the preset frequency difference, and the phase difference is less than or equal to the preset frequency difference, the gravity energy storage device is controlled to start and connect to the grid.

[0079] Optionally, the starting and grid-connecting system further includes: a working clutch, an electrically excited synchronous motor, a DC excitation device, a circuit breaker, and a grid-connecting contactor;

[0080] The first end of the electrically excited synchronous motor is connected to the first end of the grid-connecting contactor, and the second end of the electrically excited synchronous motor is connected to the first end of the circuit breaker through the DC excitation device;

[0081] The third end of the electrically excited synchronous motor is connected to the gearbox of the gravity energy storage device through the working clutch;

[0082] The second end of the circuit breaker and the second end of the grid-connecting contactor are respectively connected to the power grid;

[0083] The electrically excited synchronous motor is coaxially connected to the asynchronous starting motor;

[0084] When the speed of the asynchronous starting motor is greater than or equal to a predetermined proportion of the preset speed threshold, the circuit breaker closes, the DC excitation device is put into operation, and the stator of the electrically excited synchronous motor starts to build up voltage;

[0085] When the gravity energy storage device starts to connect to the grid, the grid-connecting contactor closes;

[0086] When the gravity energy storage device completes starting and grid-connecting, the grid-connecting clutch disconnects, and the working clutch remains closed.

[0087] Based on the same inventive concept, a computer device includes: one or more processors;

[0088] The processor is used to store one or more programs;

[0089] When the one or more programs are executed by the one or more processors, the starting and grid-connecting method of the gravity energy storage device as described in any one of the above is implemented.

[0090] Based on the same inventive concept, a computer-readable storage medium stores a computer program, and when the computer program is executed, the starting and grid-connecting method of the gravity energy storage device as described in any one of the above is implemented.

[0091] Compared with the prior art, the beneficial effects of the present invention are:

[0092] The present invention provides a starting and grid - connecting method and a starting and grid - connecting system for a gravity energy storage device. The starting and grid - connecting method of the gravity energy storage device replaces a large - capacity frequency - conversion starting device with an asynchronous starting motor and a frequency converter, reducing the investment cost of the gravity energy storage technology engineering construction. And through the three - phase current of the asynchronous starting motor and the feedback speed of the rotor in the asynchronous starting motor, the output current of the frequency converter can be effectively adjusted, thereby effectively adjusting the speed of the asynchronous starting motor. Based on the adjusted speed, the gravity energy storage device is controlled to start and connect to the grid, so as to realize the safe and stable start - up and grid - connected operation of the gravity energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 It is a flowchart of a starting and grid - connecting method for a gravity energy storage device provided by the present invention;

[0094] Figure 2 It is a schematic diagram of a gravity energy storage system provided by the present invention;

[0095] Figure 3 It is a schematic diagram of a gravity energy storage mechanical system provided by the present invention;

[0096] Figure 4 It is a schematic diagram of a frequency - converter topology provided by the present invention;

[0097] Figure 5 It is a flowchart of another starting and grid - connecting method for a gravity energy storage device provided by the present invention;

[0098] Figure 6 It is a flowchart of yet another starting and grid - connecting method for a gravity energy storage device provided by the present invention;

[0099] Figure 7 It is a schematic diagram of a control strategy for an asynchronous starting motor provided by the present invention;

[0100] Figure 8 It is a flowchart of yet another starting and grid - connecting method for a gravity energy storage device provided by the present invention;

[0101] Figure 9 It is a schematic diagram of the machine - side control of a frequency converter in the pre - grid - connecting stage provided by the present invention;

[0102] Figure 10 It is a schematic diagram of a starting and grid - connecting system for a gravity energy storage device provided by the present invention;

[0103] Figure 11 It is a block diagram of a computer device provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0104] Example 1:

[0105] Figure 1The flowchart of a starting and grid - connecting method for a gravity energy storage device provided by the present invention is as follows Figure 1 As shown, the starting and grid - connecting method may include the following steps:

[0106] In step 101, when the grid - connecting clutch in the starting and grid - connecting system is closed, the three - phase current of the asynchronous starting motor in the starting and grid - connecting system and the feedback speed of the rotor in the asynchronous starting motor are acquired.

[0107] Among them, the starting and grid - connecting system includes a series - connected grid - connecting clutch, an asynchronous starting motor, and an inverter. The starting and grid - connecting system is connected to the gravity energy storage device through the grid - connecting clutch, and the inverter is also connected to the power grid.

[0108] In step 102, based on the three - phase current and the feedback speed, the speed of the asynchronous starting motor is adjusted through the inverter.

[0109] In step 103, based on the adjusted speed, the gravity energy storage device is controlled to start and connect to the grid.

[0110] It should be noted that the starting and grid - connecting system can also be called a starting and grid - connecting device, or a starting and grid - connecting device for a gravity energy storage system. The topology of the gravity energy storage system (i.e., the gravity energy storage device) proposed by the present invention is as follows Figure 2 As shown, the gravity energy storage system is divided into a gravity energy storage mechanical system and an electrical system, or the gravity energy storage system is structurally divided into a mechanical system and an electrical system. The electrical system includes an electrically - excited synchronous motor and a DC excitation device. The first end of the electrically - excited synchronous motor is connected to the first end of the grid - connecting contactor. The second end of the electrically - excited synchronous motor is connected to the first end of the circuit breaker through the DC excitation device. The third end of the electrically - excited synchronous motor is connected to the gearbox of the gravity energy storage mechanical system through clutch 1 (i.e., the working clutch). The second end of the circuit breaker and the second end of the grid - connecting contactor are connected to the power grid through a transformer.

[0111] The topology of the starting and grid - connecting device for the gravity energy storage system proposed by the present invention is as follows Figure 2 As shown, the starting and grid - connecting device for the gravity energy storage system of the present invention adds clutch 2 (i.e., the grid - connecting clutch), an asynchronous motor, and an inverter on the mechanical system side to form a starting device. That is, the starting and grid - connecting device for the gravity energy storage system proposed by the present invention includes: clutch 2, an asynchronous starting motor, and an inverter. One end of the asynchronous starting motor is connected to the gearbox in the gravity energy storage mechanical system through clutch 2. One end of the asynchronous starting motor is connected to the power grid through the inverter. The electrically - excited synchronous motor is coaxially connected to the asynchronous starting motor. The rated power of the small - capacity asynchronous motor (i.e., the asynchronous starting motor) is selected to be 5% - 15% of the synchronous motor.

[0112] Figure 3Schematic diagram of a gravity energy storage mechanical system provided by the present invention, as Figure 3 shown, the gravity energy storage mechanical system includes a plurality of discrete energy storage mass blocks (i.e., multiple discrete energy storage mass blocks), a transmission chain, a transmission shaft, and a transmission device including a gearbox. The gearbox in the transmission device is connected to the multiple discrete energy storage mass blocks through the transmission chain. For the gravity energy storage mechanical system, when the system is connected to the grid and in the charging condition, the electrically excited synchronous motor takes energy from the grid, and the transmission device drags the multiple discrete energy storage mass blocks to move upward on the transmission chain to complete the conversion of electrical energy into gravitational potential energy. When the system is in the discharging condition, the multiple discrete energy storage mass blocks rely on their own gravity mg to drag the transmission device to complete the downward movement on the transmission chain, and the transmission device drags the electrically excited synchronous motor to reverse, converting the gravitational potential energy into electrical energy and outputting it to the grid.

[0113] On the stator side of the electrically excited synchronous motor in the electrical system, it is connected to the transformer through a bus, and the rotor of the synchronous motor is connected to the transmission device. When the system stores energy, it is powered by the grid, and the synchronous motor operates as a motor to drive the mechanical system. When the system discharges, the mechanical system drags the synchronous motor to reverse, and the motor operates in the generating state.

[0114] The starting and grid connection device of the gravity energy storage system starts the electrically excited synchronous motor when the system starts, and cuts off the clutch 2 when the system is connected to the grid to complete the separation of the starting and grid connection device from the gravity energy storage system.

[0115] Exemplarily, Figure 4 Schematic diagram of a frequency converter topology provided by the present invention, as Figure 4 shown, the frequency converter includes a parallel capacitor C, a grid-side converter, and a machine-side converter. Among them, the voltage across the capacitor is U dc , the grid-side converter includes three grid-side converter bridge arms, and the three grid-side converter bridge arms are connected in parallel to form a grid-side busbar end. The midpoints of the three grid-side converter bridge arms are respectively connected to the A-phase u a , B-phase u b and C-phase u c of the power grid through inductors L1 and resistors R1. The machine-side converter includes three machine-side converter bridge arms, and the three machine-side converter bridge arms are connected in parallel to form a machine-side busbar end. The machine-side busbar end is connected to the grid-side busbar end. The midpoints of the three machine-side converter bridge arms are respectively connected to the three phases of the asynchronous starting motor, and the conduction state of the switching tubes in the frequency converter is controlled through three-phase current and feedback speed to change the current output by the frequency converter to the asynchronous starting motor, so as to adjust the speed of the asynchronous starting motor.

[0116] Exemplarily, Figure 5 Flowchart of another starting and grid connection method for a gravity energy storage device provided by the present invention, as Figure 5 shown, as above Figure 1The implementation manner of the illustrated embodiment may include the following steps:

[0117] Step S1: Close clutches 1 and 2. The asynchronous starting motor is connected to the power grid through the converter, and the electro-excited synchronous motor is driven by the asynchronous motor to run idly through starting.

[0118] Step S2: When the speed of the synchronous motor reaches 90% of the rated speed, the DC excitation device starts to excite and build voltage, and the synchronous motor is in no-load operation.

[0119] Step S3: When the synchronous motor reaches the rated speed, enable the control strategy of the machine-side converter in the pre-parallel grid connection stage, and by finely adjusting the speed of the synchronous motor, make its terminal voltage meet the grid connection conditions.

[0120] Step S4: Close the grid connection contactor, the system completes grid connection, disconnect clutch 2, the asynchronous starting motor exits operation, and the gravity energy storage system completes grid-connected operation.

[0121] The above Figure 5 The specific implementation manner shown is as follows: When the system starts, connect the frequency converter to the power grid. The frequency converter adopts a control method with a speed outer loop and a torque inner loop to start the asynchronous motor. The rotor of the asynchronous starting motor is coaxially connected to the rotor of the electro-excited synchronous motor through clutch 2. During the starting process of the asynchronous motor, the rotor of the synchronous motor also accelerates and starts. In the initial stage of motor starting, the synchronous motor (i.e., the electro-excited synchronous motor) is in no-load operation (at this time, the DC excitation device is not put into operation). When the rotor speed of the synchronous motor reaches 90% of the rated speed, the circuit breaker closes, the DC excitation device is put into operation, and the synchronous motor starts to build voltage on the stator side. When the speed of the synchronous motor reaches the rated speed and the synchronous motor completes voltage build-up, the system enters the pre-parallel grid connection stage. In the pre-parallel grid connection stage of the system, by performing additional control on the speed loop of the frequency converter, fine adjustment of the speed of the synchronous motor is achieved to meet the conditions of voltage amplitude difference, frequency difference, and phase difference on both sides of the grid connection contactor to meet the grid connection conditions. When the grid connection conditions are met, the grid connection contactor closes, and the gravity energy storage system completes all operations from starting to grid connection.

[0122] For a gravity energy storage system with a megawatt-level power rating, a starting method and device for a high-voltage large-capacity electro-excited synchronous motor of the present invention are provided to achieve safe and stable starting and grid-connected operation of the gravity energy storage system. The starting grid connection device and method proposed by the present invention can achieve smooth starting of the high-voltage large-capacity synchronous motor in the gravity energy storage system. In addition, when the system starts and enters the pre-parallel grid connection stage, through additional speed fine adjustment control, the amplitude, phase, and frequency difference between the terminal voltage of the synchronous motor and the grid voltage meet the grid connection conditions, realizing shock-free grid connection of the system at any time.

[0123] Figure 6A flowchart of another method for starting and connecting to the grid of a gravity energy storage device provided by the present invention is shown in FIG. Figure 6 As shown above Figure 1 Possible implementations of step 102 may include the following steps:

[0124] In step 1021, a spatial angle is obtained based on a preset rotor flux, a preset rotational speed and the feedback rotational speed.

[0125] Possible implementation methods of this step may include: calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference; using a speed regulator to adjust the standby speed difference to obtain a reference torque current; and calculating a spatial angle based on the reference torque current and the feedback speed.

[0126] It should be noted that the feedback speed can also be called the rotor mechanical angular velocity. The rotor flux orientation adopts an indirect orientation method, and only the spatial angle of the rotor flux is calculated. The spatial angle satisfies the following formula:

[0127]

[0128] Among them, θ e is the spatial angle, is the angular velocity of the Park transform, ω r is the feedback speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the coaxial equivalent windings of the stator and rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor flux on the direct axis.

[0129] In step 1022, based on the space angle, the three-phase current is transformed by using Clarke transformation and Park transformation to obtain the excitation current and torque current of the rotor.

[0130] It should be noted that the three-phase current is converted into α-axis current component and β-axis current component by Clarke transformation, and based on the spatial angle, the α-axis current component and β-axis current component are converted into the rotor excitation current (d-axis current component) and torque current (q-axis current component) by Park transformation respectively.

[0131] In step 1023, based on the excitation current, the torque current and the space angle, the preset regulator and the inverse Park transform are used to process the preset rotor flux, the preset speed and the feedback speed to obtain the α-axis voltage component and the β-axis voltage component.

[0132] Among them, the preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator, and a stator current excitation component regulator;

[0133] A possible implementation of this step may include: based on the preset speed and the feedback speed, using the speed regulator to obtain a reference torque current; using the flux current conversion to convert the preset rotor flux to obtain a reference excitation current; based on the reference torque current and the torque current, using the stator current torque component regulator to obtain a torque voltage; based on the reference excitation current and the excitation current, using the stator current excitation component regulator to obtain an excitation voltage; based on the torque voltage, the excitation voltage, and the spatial angle, using the inverse Park transformation to obtain the α-axis voltage component and the β-axis voltage component.

[0134] It should be noted that the obtaining of the α-axis voltage component and the β-axis voltage component by using the inverse Park transformation based on the torque voltage, the excitation voltage, and the spatial angle may include: taking the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage; taking the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage; based on the spatial angle, using the inverse Park transformation to transform the reference torque voltage and the reference excitation voltage to obtain the α-axis voltage component and the β-axis voltage component.

[0135] In step 1024, based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starting motor is adjusted through the frequency converter.

[0136] Exemplarily, the control strategy of the asynchronous starting motor is as Figure 7 shown. In the figure, ASR is the speed regulator, ACMR is the stator current excitation component regulator, ACTR is the stator current torque component regulator, and the regulators all adopt PI (proportional-integral controller) controllers. FBS is the speed sensor. The speed regulator adopts a closed-loop control mode, and the flux adopts an open-loop control. By detecting the three-phase currents i a 、i b and i c of the stator of the asynchronous motor, two coordinate transformations (abc / αβ transformation, i.e., Clark transformation, αβ / dq transformation, i.e., Park transformation) are performed to obtain the excitation current component i sd and the torque current component i sq of the rotor current. The speed set value (i.e., the preset speed) is compared with the speed feedback value ω r (i.e., the feedback speed) measured by the FBS. The difference between them passes through the speed regulator to obtain the reference value of the torque current component Through a given value of the rotor flux linkage (preset rotor flux linkage) The reference value of the exciting current is obtained through conversion (i.e., the reference exciting current), the reference value of the torque current component (i.e., the reference torque current) And the reference value of the exciting current component Respectively pass through the ACTR and ACMR regulators and are added to the introduced deviation structure terms (i.e., the exciting deviation voltage and the torque deviation voltage) u sdc 、u sqc To obtain the corresponding voltage reference values (i.e., the reference exciting voltage) And (i.e., the reference torque voltage) And combined with the rotor flux linkage θ obtained by the indirect orientation method e Perform coordinate transformation to obtain the reference values of the voltage components And Thus, an SVPWM algorithm is established to control the frequency converter. By multiplying the reference value of the torque current component With L m R r / L r The slip angular frequency is obtained through product calculation Slip angular frequency Is superimposed with the feedback speed ω r To obtain the angular velocity of the Park transformation For the angular velocity of the Park transformation Perform Laplace transform (1 / S) to obtain the spatial angle θ e , where R r Is the resistance of the rotor winding, L m Is the mutual inductance between the stator and the rotor coaxial equivalent windings, L r Is the self-inductance of the rotor equivalent two-phase windings.

[0137] Still taking Figure 7 The control strategy of the asynchronous starting motor shown, the specific implementation of the starting and grid-connecting method provided by the present invention may include: collecting the three-phase currents i of the stator in the asynchronous starting motor through the speed sensor FBS a 、i b And i c , successively perform two coordinate transformations of abc / αβ transformation and αβ / dq transformation to obtain the exciting current component i of the rotor current sd And the torque current component i sq , use the flux linkage-current conversion to convert the preset rotor flux linkage To obtain the reference exciting current For the feedback speed ω r And the preset speed The difference is calculated to obtain the rotational speed difference, and the speed regulator ASR is used to adjust the rotational speed difference to obtain the reference torque current. Calculate the first current difference between the reference value of the exciting current and the exciting current component, and the second current difference between the reference value of the torque current and the torque current reference value; use the stator current exciting component regulator ACMR to adjust the first current difference to obtain the exciting voltage u. sd , and use the stator current torque component regulator ACTR to adjust the second current difference to obtain the torque voltage u. sq , subtract the exciting deviation voltage u. sdc from the exciting voltage to obtain the reference exciting voltage. Subtract the torque deviation voltage u. sqc from the torque voltage to obtain the reference torque voltage. Based on the spatial angle of the rotor flux linkage, use the Park inverse transformation (dq / αβ transformation) to perform coordinate transformation on the reference quantities of the exciting voltage and the torque voltage respectively to obtain the α-axis component of the voltage. and the β-axis component. The SVPWM algorithm is used for the α-axis component and the β-axis component of the voltage to control the rotational speed of the rotor in the asynchronous starting motor.

[0138] During the starting process of the gravity energy storage system, the clutch 2 is closed, and the rotor of the synchronous motor is driven by the asynchronous starting motor to complete the acceleration start. The control strategy for the system starting process needs to be formulated for the asynchronous starting motor. Assuming that the space harmonics are ignored, the three-phase windings of the asynchronous motor are symmetric, and the magnetomotive force generated is distributed sinusoidally along the air gap; the magnetic circuit saturation is ignored, and the self-inductance and mutual inductance of each winding are constant; the core loss is ignored; the influence of frequency and temperature changes on the winding resistance is not considered. Since the three-phase original dynamic model of the asynchronous motor is quite complex, its model is simplified by means of coordinate transformation. The d-axis of the asynchronous motor in the dq rotating coordinate system is oriented in the direction of the rotor flux linkage, and the relationship between the voltage and current of the asynchronous motor is obtained as follows.

[0139]

[0140] In the formula, u. sd and u. sq are the d-axis and q-axis components of the stator voltage respectively, R. s is the resistance of the stator winding, L. s is the self-inductance of the equivalent two-phase windings of the stator, L. m is the mutual inductance between the stator and the coaxial equivalent windings of the rotor, L. r is the self-inductance of the equivalent two-phase windings of the rotor, i. sd and i. sq are the d-axis and q-axis components of the stator current respectively, σ is the leakage magnetic coefficient of the motor, ω. e is the angular velocity of the dq rotating coordinate system (i.e., the Park transformation), ψ.rd is the component of the rotor flux linkage on the d-axis (i.e., the direct axis), where ψ rd = ψ r , ψ r is the rotor flux linkage, t is time, and d is the derivative symbol.

[0141] Since the rotor flux linkage is inversely proportional to the speed in the field-weakening region, the back electromotive force term ω e (L m / L r )ψ rd does not increase and has a small component above the base speed and can be ignored in engineering. Therefore, the handling of the cross-coupling term becomes the key to the decoupling control of the induction motor.

[0142] Through the introduction of the current loop and the mathematical model of Equation (1.1) (i.e., the relationship between the voltage and current of the induction motor), the deviation coupling terms (excitation deviation voltage and torque deviation voltage) obtained are

[0143]

[0144] where u sdc , u sqc are the excitation deviation voltage and torque deviation voltage respectively, L s is the self-inductance of the equivalent two-phase stator winding, i sd , i sq are the d-axis and q-axis components of the stator current respectively, σ is the leakage coefficient of the motor, and ω e is the angular velocity of the dq rotating coordinate system.

[0145] Deviation decoupling has stronger robustness to motor parameter changes than feedback decoupling.

[0146] The electromagnetic torque expression of the induction motor in the dq coordinate system is:

[0147]

[0148] where: T e is the electromagnetic torque output by the induction starting motor, n p is the number of pole pairs of the induction motor, ψ r is the rotor flux linkage, i sq are the q-axis components of the stator current respectively, L m is the mutual inductance between the stator and the rotor coaxial equivalent windings, and L r is the self-inductance of the rotor equivalent two-phase winding.

[0149] Since the induction motor is coaxial with the synchronous motor and serves as the starting motor of the synchronous motor, from the torque balance, we can obtain:

[0150]

[0151] Where: T L ' is the input mechanical torque of the synchronous motor.

[0152] The mechanical motion equation of the synchronous motor during starting is:

[0153]

[0154] Where: T e ' is the electromagnetic torque of the synchronous motor. The synchronous motor is in an idling state during the startup process. e '=0, J is the moment of inertia of the gravity energy storage system converted to the synchronous motor side, ω is the mechanical angular velocity of the synchronous motor, T L ' is the input mechanical torque of the synchronous motor, n' p is the number of pole pairs of the synchronous motor, where t is the time and d is the derivative sign.

[0155] The rotor mechanical speed of the synchronous motor will start running according to equation (1.5).

[0156] Figure 8 A flowchart of another method for starting and connecting to the grid of a gravity energy storage device provided by the present invention is shown in FIG. Figure 8 As shown above Figure 1 Possible implementations of step 103 may include the following steps:

[0157] In step 1031, when the adjusted speed reaches a preset speed threshold, the speed of the asynchronous starting motor is adjusted based on the grid voltage and the terminal voltage of the synchronous motor, and the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system are determined.

[0158] Possible implementation methods of this step may include: obtaining the quadrature-axis component of the synchronous motor terminal voltage based on the grid voltage and the synchronous motor terminal voltage; obtaining a standby voltage difference by taking the difference between the quadrature-axis component and the quadrature-axis reference voltage; processing the standby voltage difference using a proportional-integral controller to obtain a speed correction; adjusting the speed of the asynchronous starting motor based on the speed correction to determine the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system.

[0159] It should be noted that by using a proportional-integral controller, the standby voltage difference is processed to obtain the speed correction amount of the synchronous motor. Then, the speed correction amount of the synchronous motor is converted into the speed correction amount of the induction starting motor, and the speed of the induction starting motor is adjusted through the speed correction amount of the induction starting motor to achieve the purpose of adjusting the speed of the synchronous motor. When the regulating device reaches the preset speed threshold, based on the fact that the amplitude difference and frequency difference between the grid voltage and the terminal voltage of the synchronous motor already meet the grid connection conditions, the torque of the induction starting motor is finely adjusted to ensure that the phase difference of the synchronous motor meets the grid connection conditions.

[0160] The specific implementation manner of controlling the gravity energy storage device to start and connect to the grid based on the voltage amplitude difference, the frequency difference, and the phase difference in the above embodiments may include: when the voltage amplitude difference is less than or equal to the preset voltage amplitude difference, the frequency difference is less than or equal to the preset frequency difference, and the phase difference is less than or equal to the preset frequency difference, controlling the gravity energy storage device to start and connect to the grid.

[0161] In step 1032, based on the voltage amplitude difference, the frequency difference, and the phase difference, the gravity energy storage device is controlled to start and connect to the grid.

[0162] It should be noted that when an electric-excitation synchronous motor is started by an auxiliary motor, since the starting motor adopts vector control based on rotor flux orientation. For the electric-excitation synchronous motor coaxially connected to it, when the speed is below 90% of the synchronous speed, the synchronous motor is in an idling operation state, and during this process T e ' = 0. When the speed of the synchronous motor reaches 90% of the rated speed, the exciter starts to excite and build voltage. During this process, the phase sequence of the three-phase electricity generated by the synchronous motor is the same as that of the grid voltage. When the speed of the synchronous motor reaches the rated speed and the excitation controller has completed voltage building, the voltage frequency, amplitude, and phase sequence at both ends of the grid connection contactor are the same, but the voltage phase angle difference still does not meet the grid connection conditions. Therefore, an adaptive algorithm is designed to control the voltage phase angle difference at both ends of the grid connection contactor to zero.

[0163] Exemplarily, the machine-side control of the frequency converter in the pre-grid connection stage is as Figure 9 shown. In the quasi-synchronous stage, the grid voltage u g(abc) is phase-locked, and the terminal voltage u of the synchronous motor m(abc) is oriented according to the grid voltage. To ensure that the inrush current value at the moment of grid connection is minimized, the reference value of the q-axis component (quadrature-axis reference voltage) of the synchronous motor is given as 0, and the q-axis component of the terminal voltage (quadrature-axis component of the terminal voltage of the synchronous motor) u mq is compared with the reference value , and the difference is output through a PI controller to obtain the speed correction amount ω of the synchronous motor cor , and ωcor Through the adder into Figure 7 The speed loop based on rotor flux oriented vector control is used as the speed feedback. This control method is used to fine-tune the speed of the synchronous motor, thereby controlling the q-axis component of the generator terminal voltage to 0, making the voltage phase difference at both ends of the grid-connected contactor 0, and achieving the purpose of small grid-connected impact current of the gravity energy storage system.

[0164]

[0165] Where:ω cor is the speed correction, K p , K i are the proportional-integral coefficients of the speed fine-tuning controller, is the voltage q-axis given value (i.e. quadrature axis reference voltage), u mq is the q-axis component of the synchronous motor terminal voltage.

[0166] As above Figure 9 The machine-side control strategy shown in the figure, when the feedback speed of the rotor in the asynchronous starting motor is greater than the preset speed (i.e. the rated speed), the switch S is closed to enable the machine-side converter control strategy in the pre-grid connection stage, and the grid voltage u is controlled by using PLL (Phase-Locked Loop). g(abc) Phase lock is performed to obtain the standby phase θ g , based on the standby phase θ g , using Clarke transformation to calculate the synchronous motor terminal voltage u m(abc) Orientation is performed to obtain the quadrature axis component u of the synchronous motor terminal voltage mq , the quadrature component of the synchronous motor terminal voltage and the voltage reference value (i.e. reference voltage) Perform difference calculation to obtain the standby voltage difference, use the PI controller to process the terminal voltage difference, and obtain the speed correction value ω of the synchronous motor cor , based on the speed correction amount, the speed of the synchronous motor is adjusted.

[0167] The present invention proposes a grid-connected startup device and method for a gravity energy storage system, which mainly includes the following contents:

[0168] 1) The device includes an asynchronous starting motor, a frequency converter, and a clutch. It is coaxially connected to the main motor of the gravity energy storage system through a small-capacity asynchronous motor and serves as the starting motor of the gravity energy storage system.

[0169] 2) The method is characterized in that the electric excitation synchronous motor of the gravity energy storage system is smoothly started by adopting rotor flux oriented vector control for the asynchronous starting motor. After that, when the synchronous motor enters the pre-grid connection stage, the synchronous motor has completed the excitation and voltage building. Through the additional control of the synchronous motor speed fine-tuning, the phase difference between the terminal voltage of the gravity energy storage system and the grid voltage is achieved to be 0, thereby achieving the purpose of completing impact-free grid connection of the gravity energy storage system at any time.

[0170] Embodiment 2:

[0171] Figure 10 A schematic diagram of a starting grid-connected system for a gravity energy storage device provided by the present invention, such as Figure 10 As shown, the starting grid-connected system may include: a grid-connected clutch, an asynchronous starting motor, a frequency converter and a controller;

[0172] The grid-connected clutch, the asynchronous starting motor and the frequency converter are connected in series in sequence; the starting grid-connected system is connected to the gravity energy storage device through the grid-connected clutch, and the frequency converter is also connected to the power grid;

[0173] The controller is connected to the asynchronous starting motor and the frequency converter; the controller is used to obtain the three-phase current of the asynchronous starting motor and the feedback speed of the rotor in the asynchronous starting motor when the grid-connected clutch is closed; based on the three-phase current and the feedback speed, the speed of the asynchronous starting motor is adjusted through the frequency converter; based on the adjusted speed, the gravity energy storage device is controlled to start and connect to the grid.

[0174] Optionally, the controller is specifically used to:

[0175] Obtaining a spatial angle based on a preset rotor flux, a preset speed and the feedback speed;

[0176] Based on the spatial angle, the three-phase current is transformed by using Clarke transformation and Park transformation to obtain the excitation current and torque current of the rotor;

[0177] Based on the excitation current, the torque current and the space angle, the preset rotor flux, the preset speed and the feedback speed are processed by using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component;

[0178] Based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starter motor is adjusted by the frequency converter.

[0179] Optionally, the controller is specifically used to:

[0180] Calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference;

[0181] Using a speed regulator, the standby speed difference is adjusted to obtain a reference torque current;

[0182] A spatial angle is calculated based on the reference torque current and the feedback rotation speed.

[0183] Optionally, the spatial angle satisfies the following formula:

[0184]

[0185] Among them, θ e is the spatial angle, is the angular velocity of the Park transform, ω r is the feedback speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the coaxial equivalent windings of the stator and rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor flux on the direct axis.

[0186] Optionally, the preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator and a stator current excitation component regulator;

[0187] The controller is specifically used for:

[0188] Based on the preset speed and the feedback speed, using the speed regulator, a reference torque current is obtained;

[0189] Using the flux current conversion, the preset rotor flux is converted to obtain a reference excitation current;

[0190] Based on the reference torque current and the torque current, using the stator current torque component regulator, a torque voltage is obtained;

[0191] Based on the reference excitation current and the excitation current, using the stator current excitation component regulator, an excitation voltage is obtained;

[0192] Based on the torque voltage, the excitation voltage and the space angle, an α-axis voltage component and a β-axis voltage component are obtained by using an inverse Park transform.

[0193] Optionally, the controller is specifically used to:

[0194] Calculating the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage;

[0195] Calculating the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage;

[0196] Based on the spatial angle, the reference torque voltage and the reference excitation voltage are transformed by using inverse Park transformation to obtain an α-axis voltage component and a β-axis voltage component.

[0197] Optionally, the controller is specifically used to:

[0198] When the adjusted speed reaches a preset speed threshold, the speed of the asynchronous starting motor is adjusted based on the grid voltage and the terminal voltage of the synchronous motor, and the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system are determined;

[0199] Based on the voltage amplitude difference, the frequency difference and the phase difference, the gravity energy storage device is controlled to start and connect to the grid.

[0200] Optionally, the controller is specifically used to:

[0201] Based on the grid voltage and the synchronous motor terminal voltage, a quadrature axis component of the synchronous motor terminal voltage is obtained;

[0202] Calculating the difference between the quadrature-axis component and the quadrature-axis reference voltage to obtain a standby voltage difference;

[0203] Using a proportional-integral controller, the standby voltage difference is processed to obtain a speed correction value;

[0204] Based on the speed correction amount, the speed of the asynchronous starting motor is adjusted to determine the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system.

[0205] Optionally, the controller is specifically used to:

[0206] When the voltage amplitude difference is less than or equal to the preset voltage amplitude difference, the frequency difference is less than or equal to the preset frequency difference, and the phase difference is less than or equal to the preset frequency difference, the gravity energy storage device is controlled to start and connect to the grid.

[0207] Optionally, the starting grid-connected system further comprises: a working clutch, an electrically excited synchronous motor, a DC excitation device, a circuit breaker and a grid-connected contactor;

[0208] The first end of the electrically excited synchronous motor is connected to the first end of the grid-connected contactor, and the second end of the electrically excited synchronous motor is connected to the first end of the circuit breaker through the DC excitation device;

[0209] The third end of the electrically excited synchronous motor is connected to the gear box of the gravity energy storage device through the working clutch;

[0210] The second end of the circuit breaker and the second end of the grid-connected contactor are respectively connected to the power grid;

[0211] The electrically excited synchronous motor is coaxially connected to the asynchronous starting motor;

[0212] When the rotational speed of the asynchronous starting motor is greater than or equal to a predetermined ratio of the preset rotational speed threshold, the circuit breaker closes, the DC excitation device is put into operation, and the stator of the electrically excited synchronous motor starts to build up voltage;

[0213] When the gravity energy storage device starts and is connected to the grid, the grid-connected contactor closes;

[0214] When the gravity energy storage device completes starting and grid connection, the grid-connected clutch disconnects, and the working clutch remains closed.

[0215] Embodiment 3:

[0216] Based on the same inventive concept, as Figure 11 shown, the present invention further provides a computer device, which includes a processor and a memory. The memory is used to store a computer program. The computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits

[0217] (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a method for starting and grid connecting a gravity energy storage device in the above embodiment.

[0218] Embodiment 4:

[0219] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device and is used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and this storage space stores the operating system of the terminal. Moreover, in this storage space, there are also stored one or more instructions suitable for being loaded and executed by the processor, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The one or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the steps of the method for starting and connecting to the grid of a gravity energy storage device in the above-mentioned embodiment.

[0220] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0221] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0222] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and this instruction device implements the functions in Figure 1 one flow or multiple flows and / or blocks Figure 1The functions specified in one or more boxes.

[0223] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide for implementing in the process Figure 1 One or more processes and / or boxes Figure 1 The steps of the functions specified in one or more boxes.

[0224] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A starting and grid-connection method for a gravity energy storage device, characterized in that, The grid-connection startup method comprises: When the grid-connected clutch in the starting grid-connected system is closed, the three-phase current of the asynchronous starting motor in the starting grid-connected system and the feedback speed of the rotor in the asynchronous starting motor are obtained, wherein the starting grid-connected system comprises a grid-connected clutch, an asynchronous starting motor and a frequency converter connected in series, the starting grid-connected system is connected to the gravity energy storage device through the grid-connected clutch, and the frequency converter is also connected to the power grid; Based on the three-phase current and the feedback speed, adjusting the speed of the asynchronous starter motor through the frequency converter; Based on the adjusted rotation speed, the gravity energy storage device is controlled to start and connect to the grid.

2. The start-up and grid connection method according to claim 1, characterized in that The adjusting the speed of the asynchronous starter motor by the frequency converter based on the three-phase current and the feedback speed includes: Obtaining a spatial angle based on a preset rotor flux, a preset speed and the feedback speed; Based on the spatial angle, the three-phase current is transformed by using Clarke transformation and Park transformation to obtain the excitation current and torque current of the rotor; Based on the excitation current, the torque current and the space angle, the preset rotor flux, the preset speed and the feedback speed are processed by using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component; Based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starter motor is adjusted by the frequency converter.

3. The starting and grid-connection method according to claim 2, wherein The obtaining of the spatial angle based on the preset rotor flux, the preset speed and the feedback speed includes: Calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference; Using a speed regulator, the standby speed difference is adjusted to obtain a reference torque current; A spatial angle is calculated based on the reference torque current and the feedback rotation speed.

4. The starting and grid-connecting method according to claim 3, wherein The spatial angle satisfies the following formula: Among them, θ e is the spatial angle, is the angular velocity of Park transformation, ω r is the feedback rotational speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the stator and the coaxial equivalent winding of the rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor magnetic flux on the direct axis.

5. The starting and grid-connecting method according to any one of claims 2 to 4, characterized in that The preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator and a stator current excitation component regulator; The method of processing the preset rotor flux, the preset speed and the feedback speed based on the excitation current, the torque current and the space angle using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component includes: Based on the preset speed and the feedback speed, using the speed regulator, a reference torque current is obtained; Using the flux current conversion, the preset rotor flux is converted to obtain a reference excitation current; Based on the reference torque current and the torque current, using the stator current torque component regulator, a torque voltage is obtained; Based on the reference excitation current and the excitation current, using the stator current excitation component regulator, an excitation voltage is obtained; Based on the torque voltage, the excitation voltage and the space angle, an α-axis voltage component and a β-axis voltage component are obtained by using an inverse Park transform.

6. The starting and grid-connection method according to claim 5, wherein The method of obtaining the α-axis voltage component and the β-axis voltage component by using the inverse Park transform based on the torque voltage, the excitation voltage and the space angle includes: Calculating the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage; Calculating the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage; Based on the spatial angle, the reference torque voltage and the reference excitation voltage are transformed by using inverse Park transformation to obtain an α-axis voltage component and a β-axis voltage component.

7. The starting and grid-connecting method according to claim 1, characterized in that, The method of controlling the gravity energy storage device to start and connect to the grid based on the adjusted rotation speed includes: When the adjusted speed reaches a preset speed threshold, the speed of the asynchronous starting motor is adjusted based on the grid voltage and the terminal voltage of the synchronous motor, and the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system are determined; Based on the voltage amplitude difference, the frequency difference and the phase difference, the gravity energy storage device is controlled to start and connect to the grid.

8. The starting and grid-connection method according to claim 7, characterized in that, The method of adjusting the rotation speed of the asynchronous starting motor based on the grid voltage and the terminal voltage of the synchronous motor, and determining the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system, includes: Based on the grid voltage and the synchronous motor terminal voltage, a quadrature axis component of the synchronous motor terminal voltage is obtained; Calculating the difference between the quadrature-axis component and the quadrature-axis reference voltage to obtain a standby voltage difference; Using a proportional-integral controller, the standby voltage difference is processed to obtain a speed correction value; Based on the speed correction amount, the speed of the asynchronous starting motor is adjusted to determine the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system.

9. The start-up and grid connection method according to claim 7, characterized in that The controlling the gravity energy storage device to start and connect to the grid based on the voltage amplitude difference, the frequency difference and the phase difference comprises: When the voltage amplitude difference is less than or equal to the preset voltage amplitude difference, the frequency difference is less than or equal to the preset frequency difference, and the phase difference is less than or equal to the preset frequency difference, the gravity energy storage device is controlled to start and connect to the grid.

10. A starting and grid-connection system for a gravity energy storage device, characterized in that, The starting and grid-connected system comprises: a grid-connected clutch, an asynchronous starting motor, a frequency converter and a controller; The grid-connected clutch, the asynchronous starting motor and the frequency converter are connected in series in sequence; The starting grid-connected system is connected to the gravity energy storage device through the grid-connected clutch, and the frequency converter is also connected to the power grid; The controller is connected to the asynchronous starting motor and the frequency converter; The controller is used to obtain the three-phase current of the asynchronous starter motor and the feedback speed of the rotor in the asynchronous starter motor when the grid-connected clutch is closed; based on the three-phase current and the feedback speed, adjust the speed of the asynchronous starter motor through the inverter; based on the adjusted speed, control the gravity energy storage device to start and connect to the grid.

11. The starting and grid-connecting system according to claim 10, characterized in that, The controller is specifically used for: Obtaining a spatial angle based on a preset rotor flux, a preset speed and the feedback speed; Based on the spatial angle, the three-phase current is transformed by using Clarke transformation and Park transformation to obtain the excitation current and torque current of the rotor; Based on the excitation current, the torque current and the space angle, the preset rotor flux, the preset speed and the feedback speed are processed by using a preset regulator and an inverse Park transform to obtain an α-axis voltage component and a β-axis voltage component; Based on the α-axis voltage component and the β-axis voltage component, the speed of the asynchronous starter motor is adjusted by the frequency converter.

12. The starting and grid-connecting system according to claim 11, characterized in that, The controller is specifically used for: Calculating the difference between the preset speed and the feedback speed to obtain a standby speed difference; Using a speed regulator, the standby speed difference is adjusted to obtain a reference torque current; A spatial angle is calculated based on the reference torque current and the feedback rotation speed.

13. The starting and grid-connecting system according to claim 12, wherein The spatial angle satisfies the following formula: Among them, θ e is the space angle, is the angular velocity of Park transformation, ω r is the feedback rotational speed, is the slip angular frequency, R r is the rotor winding resistance, i sq is the reference torque current, L m is the mutual inductance between the stator and the coaxial equivalent winding of the rotor, L r is the self-inductance of the rotor equivalent two-phase winding, ψ rd is the component of the rotor magnetic flux on the direct axis.

14. The starting and grid-connecting system according to any one of claims 11-13, characterized in that, The preset regulator includes: a speed regulator, a flux current conversion, a stator current torque component regulator and a stator current excitation component regulator; The controller is specifically used for: Based on the preset speed and the feedback speed, using the speed regulator, a reference torque current is obtained; Using the flux current conversion, the preset rotor flux is converted to obtain a reference excitation current; Based on the reference torque current and the torque current, using the stator current torque component regulator, a torque voltage is obtained; Based on the reference excitation current and the excitation current, using the stator current excitation component regulator, an excitation voltage is obtained; Based on the torque voltage, the excitation voltage and the space angle, an α-axis voltage component and a β-axis voltage component are obtained by using an inverse Park transform.

15. The starting and grid-connecting system according to claim 14, characterized in that, The controller is specifically used for: Calculating the difference between the torque deviation voltage and the torque voltage to obtain a reference torque voltage; Calculating the difference between the excitation deviation voltage and the excitation voltage to obtain a reference excitation voltage; Based on the spatial angle, the reference torque voltage and the reference excitation voltage are transformed by using inverse Park transformation to obtain an α-axis voltage component and a β-axis voltage component.

16. The starting and grid-connecting system according to claim 10, characterized in that, The controller is specifically used for: When the adjusted speed reaches a preset speed threshold, the speed of the asynchronous starting motor is adjusted based on the grid voltage and the terminal voltage of the synchronous motor, and the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system are determined; Based on the voltage amplitude difference, the frequency difference and the phase difference, the gravity energy storage device is controlled to start and connect to the grid.

17. The starting and grid-connecting system according to claim 16, characterized in that, The controller is specifically used for: Based on the grid voltage and the synchronous motor terminal voltage, a quadrature axis component of the synchronous motor terminal voltage is obtained; Calculating the difference between the quadrature-axis component and the quadrature-axis reference voltage to obtain a standby voltage difference; Using a proportional-integral controller, the standby voltage difference is processed to obtain a speed correction value; Based on the speed correction amount, the speed of the asynchronous starting motor is adjusted to determine the voltage amplitude difference, frequency difference and phase difference on both sides of the grid-connected contactor in the starting grid-connected system.

18. The starting grid-connected system according to claim 16, characterized in that, The controller is specifically used for: When the voltage amplitude difference is less than or equal to the preset voltage amplitude difference, the frequency difference is less than or equal to the preset frequency difference, and the phase difference is less than or equal to the preset frequency difference, the gravity energy storage device is controlled to start and connect to the grid.

19. The starting and grid-connecting system according to claim 10, characterized in that, The starting grid-connected system also includes: a working clutch, an electrically excited synchronous motor, a DC excitation device, a circuit breaker and a grid-connected contactor; The first end of the electrically excited synchronous motor is connected to the first end of the grid-connected contactor, and the second end of the electrically excited synchronous motor is connected to the first end of the circuit breaker through the DC excitation device; The third end of the electrically excited synchronous motor is connected to the gearbox of the gravity energy storage device through the working clutch; The second end of the circuit breaker and the second end of the grid-connected contactor are respectively connected to the power grid; The electrically excited synchronous motor is coaxially connected to the asynchronous starting motor; When the speed of the asynchronous starting motor is greater than or equal to a predetermined ratio of the preset speed threshold, the circuit breaker closes, the DC excitation device is put into operation, and the stator of the electrically excited synchronous motor starts to build voltage; When the gravity energy storage device starts to be grid-connected, the grid-connected contactor closes; When the gravity energy storage device completes the start-up grid connection, the grid-connected clutch disconnects, and the working clutch remains closed.

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