Control method, device, medium and equipment of flywheel energy storage micro-grid

Abstract

The present disclosure relates to a flywheel energy storage micro-grid control method, device, medium and equipment. The method comprises: detecting the AC voltage in the power grid on the AC bus; if the AC voltage is in a first predetermined range, controlling the grid-side converter to output reactive power to reduce the voltage on the DC bus; if the AC voltage is in a second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus; if the AC voltage is in a third predetermined range, controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus, wherein the voltage in the first predetermined range is greater than the rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range. In this way, the machine-side control and grid-side coordinated control of the flywheel energy storage micro-grid are realized in a short time, the stability of the power grid voltage is good, and the reliability is high.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of micro-grid automatic control, in particular, to a control method and device of a flywheel energy storage micro-grid, a medium and equipment. BACKGROUND

[0002] At present, the control of the flywheel energy storage micro-grid is usually to control the machine-side converter and the grid-side converter respectively, the machine-side converter controls the motor by directly affecting the speed and torque of the motor to charge and discharge, and the grid-side converter mainly controls the unit power operation of the system and stabilizes the DC bus voltage.

[0003] At present, there are few studies on high-voltage faults of the power grid, and the DC bus can be increased with hardware devices, but the regulation effect of the current voltage regulation method is sometimes not ideal. SUMMARY

[0004] The purpose of the present disclosure is to provide a control method, device, medium and equipment of a flywheel energy storage micro-grid with reliable performance and high safety.

[0005] In order to achieve the above purpose, the present disclosure provides a control method of a flywheel energy storage micro-grid, the micro-grid comprising a flywheel energy storage sub-grid, a DC bus and a grid-side converter, the flywheel energy storage sub-grid being connected to the grid-side converter through the DC bus, and the grid-side converter being connected to the power grid, the method comprising:

[0006] detecting an AC voltage in the power grid;

[0007] if the AC voltage is in a first predetermined range, controlling the grid-side converter to output reactive power to reduce the voltage on the DC bus;

[0008] if the AC voltage is in a second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus to reduce the voltage on the DC bus;

[0009] if the AC voltage is in a third predetermined range, controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus, wherein the voltage in the first predetermined range is greater than the rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

[0010] Optionally, if the AC voltage is in the second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus to reduce the voltage on the DC bus, comprises:

[0011] if the AC voltage is in the second predetermined range and the grid-side converter is controlled to output reactive power so as to decrease the voltage on the DC bus;

[0012] wherein,

[0013] is a reference value of the d-axis current of the grid-side converter when the AC voltage in the power grid is the rated voltage, is the rated voltage, U ref is the AC voltage in the power grid, i max is a maximum allowed current value of the grid-side converter, i N is a current rating of the point of common coupling, |·| is an absolute value.

[0014] Optionally, the if the AC voltage is in the second predetermined range and the grid-side converter is controlled to output reactive power so as to decrease the voltage on the DC bus, further comprises:

[0015] if the AC voltage is in the second predetermined range and the flywheel energy storage sub-grid is controlled to increase the energy received from the DC bus so as to decrease the voltage on the DC bus according to the following formula:

[0016]

[0017]

[0018] wherein, according to is a target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and is satisfied, is a target value of the q-axis current of the grid-side converter when the AC voltage is in the second predetermined range and is satisfied.

[0019] Optionally, the controlling the grid-side converter to output reactive power comprises: controlling the reactive current output by the grid-side converter to satisfy the following condition:

[0020]

[0021] wherein, is a reference value of the q-axis current of the grid-side converter when the AC voltage in the power grid is the rated voltage, is a current value of the reactive current output by the grid-side converter in the d-axis, i maxis the maximum allowed current value of the grid-side converter, and |·| is an absolute value.

[0022] Optionally, the controlling the grid-side converter to output reactive power comprises:

[0023]

[0024] wherein, is the current value of the reactive current output by the grid-side converter in the q-axis, is the rated voltage, U ref is the AC voltage in the power grid, i N is the current rating of the grid-connected point.

[0025] The present disclosure also provides a control device of a flywheel energy storage micro-grid, the micro-grid comprising a flywheel energy storage sub-grid, a DC bus and a grid-side converter, the flywheel energy storage sub-grid being connected to the grid-side converter through the DC bus, and the grid-side converter being connected to a power grid, the device comprising:

[0026] a detection module configured to detect an AC voltage in the power grid;

[0027] a first control module configured to, if the AC voltage is in a first predetermined range, control the grid-side converter to output reactive power so as to reduce a voltage on the DC bus;

[0028] a second control module configured to, if the AC voltage is in a second predetermined range, control the grid-side converter to output reactive power or control the flywheel energy storage sub-grid to increase energy received from the DC bus so as to reduce the voltage on the DC bus;

[0029] a third control module configured to, if the AC voltage is in a third predetermined range, control the flywheel energy storage sub-grid to increase energy received from the DC bus, wherein the voltage in the first predetermined range is greater than a rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

[0030] Optionally, the second control module comprises:

[0031] a first control submodule configured to, if the AC voltage is in the second predetermined range and satisfies control the grid-side converter to output reactive power so as to reduce the voltage on the DC bus;

[0032] wherein,

[0033] a reference value of a d-axis current of the grid-side converter, for an alternating voltage in the power grid being the rated voltage, a rated voltage, U ref an alternating voltage in the power grid, i max a maximum allowed current value of the grid-side converter, i N a current rating of the point of common coupling, |·| being an absolute value.

[0034] Optionally, the second control module further comprises:

[0035] a second control submodule, configured to, if the alternating voltage is in the second predetermined range and the condition is met, then control the flywheel energy storage sub-grid to increase energy received from the DC bus according to the following formula, so as to reduce the voltage on the DC bus;

[0036]

[0037]

[0038] wherein, according to a target value of a d-axis current of the grid-side converter, for an alternating voltage in the power grid being the rated voltage, a target value of a q-axis current of the grid-side converter, for an alternating voltage in the power grid being the rated voltage.

[0039] The present disclosure also provides a non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the steps of the above method provided by the present disclosure.

[0040] The present disclosure also provides an electronic device, comprising:

[0041] a memory having stored thereon a computer program;

[0042] a processor configured to execute the computer program in the memory to implement the steps of the above method provided by the present disclosure.

[0043] ​​By the technical scheme, if the AC voltage of the power grid is in a high voltage difference crossing period, the real-time power grid voltage is divided into two ranges, if it is in a lower voltage range (second predetermined range), the grid-side converter outputs reactive power or the flywheel energy storage sub-grid increases the energy received from the DC bus to reduce the DC bus voltage, if it is in a higher voltage range (third predetermined range), the flywheel energy storage sub-grid increases the storage of energy to reduce the DC bus voltage, so as to restore the power grid voltage to steady state operation. In this way, the machine-side control and grid-side coordinated control of the flywheel energy storage micro-grid are realized in a short time, the stability of the power grid voltage is good, and the reliability is high.

[0044] Other features and advantages of the present disclosure will be described in detail in the following detailed description section. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation on the present disclosure. In the drawings:

[0046] Figure 1 is a structure schematic diagram of a flywheel energy storage micro-grid in the related art;

[0047] Figure 2 is a principle diagram of a control method of a grid-side converter provided by an example embodiment;

[0048] Figure 3 is a flow chart of a control method of a flywheel energy storage micro-grid provided by an example embodiment;

[0049] Figure 4 is a flow chart of a control method of a flywheel energy storage micro-grid provided by another example embodiment;

[0050] Figure 5 is a principle diagram of an active disturbance rejection controller provided by an example embodiment;

[0051] Figure 6 is a block diagram of a control device of a flywheel energy storage micro-grid provided by an example embodiment;

[0052] Figure 7 is a block diagram of an electronic device shown by an example embodiment. DETAILED DESCRIPTION

[0053] The detailed description of the present disclosure is described in detail below in combination with the drawings. It should be understood that the detailed description described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0054] Figure 1is a structural schematic diagram of a flywheel energy storage micro-grid in the related art. Grid connection of a flywheel energy storage array system is mainly controlled by a machine-side converter and a grid-side converter. In recent years, a back-to-back double pulse width modulation (PWM) converter is widely used in the field of grid connection control of a flywheel energy storage system due to its flexible control and high power factor and other advantages. The back-to-back double PWM converter is mainly composed of a machine-side converter and a grid-side converter. The machine-side converter controls the charging and discharging of the motor by directly affecting the speed and torque of the motor, and the grid-side converter mainly controls the unit power operation of the system and stabilizes the DC bus voltage.

[0055] With large-scale access of new energy to the power grid, the stability and power quality of the power grid will be affected. The access of the flywheel energy storage array system to the power grid can absorb excess power from the power grid during high-voltage fault of the power grid and provide certain reactive power support to the power grid, while the flywheel energy storage array system can operate without being disconnected from the grid during a sudden voltage rise of the power grid. After the fault is eliminated, the flywheel energy storage array system can quickly and stably recover to the normal operating state.

[0056] In the related art, as shown in Figure 1 , the flywheel energy storage micro-grid can include a flywheel energy storage sub-network (including a flywheel, a motor, and a machine-side converter), a DC bus, and a grid-side converter. The flywheel energy storage sub-network is connected to the DC bus, and the flywheel energy storage sub-network is used to convert electrical energy from the DC bus into mechanical energy for storage or convert stored mechanical energy into electrical energy input to the DC bus. The flywheel energy storage sub-network is connected to the grid-side converter through the DC bus, and the grid-side converter is connected to the power grid. The grid-side converter is used for rectification or inversion conversion.

[0057] Among them, the micro-grid adopts an active disturbance rejection control (ADRC) controller for control. Figure 2 is a principle diagram of a control method of a grid-side converter provided by an example embodiment. As shown in Figure 2 , the ADRC controller includes a tracking differentiator (TD), an extended state observer (ESO), and a nonlinear state error feedback control law (NLSEF). The TD arranges a transition process for a set input signal, obtains a differential signal of the input signal, and produces a filtering effect on the input signal to obtain a smooth input signal. The ESO can not only estimate the state variables in the system, but also obtain the estimated value of the internal and external disturbances in the system. The nonlinear state error feedback control law outputs the system control signal to improve the control effect.

[0058] Figure 2 In the formula, v is a reference signal of the ADRC, that is, an external given signal, and y is an output signal of the controlled object. The reference signal v passes through the TD to obtain a differential signal (v1, v2), the differential signal forms an error signal (e1, e2) with an observation signal (z1, z2) of the ESO, and then passes through the NLSEF to obtain u0. b0 is a compensation factor, and Z is a state variable estimated by the ESO in real time.

[0059] In the formula, v is a reference signal of the ADRC, that is, an external given signal, and y is an output signal of the controlled object. The reference signal v passes through the TD to obtain a differential signal (v1, v2), the differential signal forms an error signal (e1, e2) with an observation signal (z1, z2) of the ESO, and then passes through the NLSEF to obtain u0. b0 is a compensation factor, and Z is a state variable estimated by the ESO in real time.

[0060] TD:

[0061] ESO:

[0062] NLSEF:

[0063] In the related art, the nonlinear function in formula (3) is:

[0064]

[0065] v1 is a tracking signal, v * is a direct current bus voltage set value (a differential tracker input signal), e is an error signal, a is a nonlinear factor, and d is a filtering factor. e1 is an error signal of v1, e2 is an error signal of v2, e0 is an error signal, u is an ADRC output value (a d-axis current), a1 is a nonlinear factor of an extended state observer, u0 is an intermediate function, t is time, k is a regulator gain, b0 is a compensation factor, z1' is a corresponding integral value, r0 is a coefficient, e0 is an error signal in a differential tracker, a0 is a nonlinear factor in the differential tracker, d0 is a filtering factor in the differential tracker, z1 is a tracking signal of y, z2 is a disturbance observation value, and b1 and b2 are ESO output error correction gains.

[0066] The nonlinear function is a core part of the active disturbance rejection controller algorithm, and the traditional fal function is not derivable at the segment point and the origin, and the continuity and smoothness of the function are poor. Therefore, the traditional fal function can be improved and optimized, and the nonlinear function nfal described below can be used to replace the fal function:

[0067] When |e|>d, the hyperbolic tangent function tanh is used to replace the sign function.

[0068] The expression of tanh is:

[0069]

[0070] The tanh function is continuous in the real number domain, and the function value is zero at the zero point, and the steepness of tanh(ax) increases with a, so the value of a can be selected to further improve the control effect.

[0071] At this time, the function nfal expression is:

[0072] fal(e, a, d) = |e| α tanh(e), |e| > d (6)

[0073] When |e| <= d, the function nfal is:

[0074] nfal(e, a, d) = xi1sine + xi2e 2 + xi3tan e (7)

[0075] Interpolation fitting is performed on the above formula (7), and the process meets the continuous derivative condition, and when e = d and e = -d, the following formula is established:

[0076] That is:

[0077] Solving:

[0078]

[0079] At this time, the function nfal expression is:

[0080]

[0081] As described above, the NLSEF is:

[0082] Wherein, the nonlinear function nfal is:

[0083]

[0084] As can be seen from the above expression, since e 2 The coefficient of the term is 0, so the convergence of the nonlinear function nfal obtained after interpolation fitting is better, and the continuity and smoothness of the nonlinear function nfal are better than those of the traditional fal function. By replacing the fal function in formula (3) with formula (11), an improved active disturbance rejection controller can be obtained.

[0085] Using the improved ADRC controller described above, the response speed is fast, the regulation ability is good, and the robustness is strong. The traditional ADRC controller has many control parameters to be adjusted, and the adjustment parameters are complex and tedious. In the improved ADRC, the number of parameters to be adjusted is reduced, so that the control system is more optimized, and has stronger anti-disturbance ability.

[0086] And, the grid-side converter is to rectify the DC voltage of the machine-side converter into three-phase voltage with the same frequency, amplitude and phase angle as the grid when operating in parallel with the grid, so as to realize grid connection. Since the reference quantity of the grid-side inverter in the three-phase coordinate system is an AC time-varying quantity, which is not conducive to the design of the controller of the grid-side inverter, the park transformation is adopted to convert the reference quantity into a DC quantity in the two-phase coordinate system, which can not only simplify the mathematical model, but also i gd and i gq There is no coupling problem, and the mathematical model of the grid-side converter in the dq coordinate system is obtained as follows:

[0087]

[0088] If the power losses of the DC side and the grid side are ignored, the active power and the reactive power flowing from the grid-side inverter to the grid are respectively:

[0089]

[0090] wherein e gd represents the d-axis component of the three-phase voltage, e gq represents the q-axis component of the three-phase voltage, U d represents the d-axis component of the DC bus voltage, U q represents the q-axis component of the DC bus voltage, i gd represents the d-axis component of the current of the grid-side converter, i gq represents the q-axis component of the current of the grid-side converter, R represents the resistance of the grid-side converter, and L represents the inductance of the grid-side converter. ω represents the phase-locked loop angular frequency, P g represents the active power, and Q g represents the reactive power.

[0091] Figure 3 is a flow chart of a control method of a flywheel energy storage micro-grid provided by an example embodiment. As shown in Figure 3 , the method comprises the following steps:

[0092] Step S101, detecting the AC voltage in the grid. The AC voltage in the grid, i.e. the grid voltage, should be stable within a small voltage range around the preset rated voltage.

[0093] Step S102, if the AC voltage is in a first predetermined range, controlling the grid-side converter to output reactive power, so as to reduce the voltage on the DC bus.

[0094] Step S103, if the AC voltage is in a second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase the energy received from the DC bus, so as to reduce the voltage on the DC bus.

[0095] If the AC voltage is in the third predetermined range, the flywheel energy storage sub-network is controlled to increase the energy received from the DC bus, wherein the voltage in the first predetermined range is greater than the rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

[0096] If the AC voltage is in the first predetermined range, it can be considered that the current power grid voltage exceeds the rated voltage in a small range, and only controlling the grid-side converter to output reactive power can control the voltage on the DC bus to a reasonable level. If the AC voltage is in the second predetermined range, it can be considered that the power grid voltage exceeds the rated voltage in a large range. If the AC voltage is in the third predetermined range, it can be considered that the power grid voltage exceeds the rated voltage in a larger range.

[0097] When the power grid voltage is in the first predetermined range, it can be considered that the power grid voltage is normal and the DC bus voltage is stable, and the flywheel energy storage array system does not work. When the power grid voltage is greater than the voltage in the third predetermined range, it can be considered that the micro-grid system is seriously malfunctioning, and the grid can be controlled to be disconnected at this time to avoid causing greater losses.

[0098] For example, the first predetermined range can be The second predetermined range can be The third predetermined range can be wherein, is the rated voltage of the power grid. If the AC voltage of the power grid is in the second predetermined range or the third predetermined range, it is in the high voltage difference ride-through period.

[0099] Through the above technical solution, if the AC voltage of the power grid is in the high voltage difference ride-through period, the real-time power grid voltage is divided into two ranges. If it is in the lower voltage range (second predetermined range), the grid-side converter is controlled to output reactive power or the flywheel energy storage sub-network is controlled to increase the energy received from the DC bus to reduce the DC bus voltage. If it is in the higher voltage range (third predetermined range), the flywheel energy storage sub-network is controlled to increase the storage of energy to reduce the DC bus voltage, so as to restore the power grid voltage to steady state operation. In this way, the machine-side control and grid-side coordinated control of the flywheel energy storage micro-grid are realized in a short time, the stability of the power grid voltage is good, and the reliability is high.

[0100] That is, the present disclosure provides a flywheel energy storage micro-grid high voltage ride-through control method based on symmetric fault, which is suitable for the case of sudden rise of power grid voltage. The control method combines the control of the grid-side converter and the control of the flywheel energy storage sub-network, determines whether to control the flywheel energy storage sub-network on the DC side to offset the energy according to the degree of sudden rise of the power grid voltage, and coordinates the machine-side and grid-side of the flywheel energy storage sub-network to realize the adjustment of active power and reactive power in a short time.

[0101] In yet another embodiment, the step S103 of controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-network to increase the energy received from the DC bus to lower the voltage on the DC bus, if the AC voltage is in the second predetermined range, can comprise: Figure 3

[0102] If the AC voltage is in the second predetermined range and the condition is satisfied, the grid-side converter is controlled to output reactive power to lower the voltage on the DC bus.

[0103] wherein,

[0104] is the reference value of the d-axis current of the grid-side converter when the AC voltage in the grid is the rated voltage, U ref is the AC voltage in the grid, is the rated voltage, i max is the maximum allowable current value of the grid-side converter, i N is the current rating of the point of common coupling, i N is the rated current of the wind turbine, and |·| is the absolute value.

[0105] If the AC voltage is in the second predetermined range, it is also necessary to consider whether the condition is satisfied. If the condition is satisfied, it can be considered that the grid-side converter can achieve the purpose of stabilizing the DC bus voltage by changing its own control strategy, and at this time the grid-side converter is controlled to output reactive power to lower the voltage on the DC bus.

[0106] In yet another embodiment, the step S103 of controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-network to increase the energy received from the DC bus to lower the voltage on the DC bus, if the AC voltage is in the second predetermined range, can further comprise:

[0107] If the AC voltage is in the second predetermined range and the condition is satisfied, the flywheel energy storage sub-network is controlled to increase the energy received from the DC bus to lower the voltage on the DC bus according to the following formula:

[0108]

[0109]

[0110] wherein, according to is the target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied, is the target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition​ At that time, the target value of the q-axis current of the grid-side converter.

[0111] In this embodiment, if the following conditions are met Therefore, it can be considered that high voltage ride-through cannot be achieved solely by outputting reactive power through the grid-side converter. In this case, it is necessary to use the flywheel energy storage subgrid for energy compensation, which can be specifically calculated using the above formula (14). and To control the d-axis and q-axis currents of the grid-side converter.

[0112] In another embodiment, the reactive power output of the control grid-side converter described above may include: the reactive current output by the control grid-side converter satisfies the following condition:

[0113]

[0114] in, This is the reference value for the q-axis current of the grid-side converter when the AC voltage in the power grid is at its rated voltage. i represents the reactive current output from the grid-side converter in the d-axis direction. max is the maximum allowable current value of the grid-side converter, and |·| is the absolute value.

[0115] In this embodiment, the above formula (15) is used to... The amplitude is limited to prevent overcurrent in the converter. By calculating the reactive current and using inductive reactive compensation, the active power output on the grid side is limited, providing reactive power support to the grid to ensure DC-side voltage stability, thereby ensuring AC bus voltage stability.

[0116] In another embodiment, the reactive power output of the control grid-side converter may further include: the reactive current output by the control grid-side converter satisfies the following condition:

[0117]

[0118] in, This represents the reactive current output from the grid-side converter in the q-axis direction. For the rated voltage, U ref i is the AC voltage in the power grid. N This is the rated current at the grid connection point.

[0119] In this embodiment, the above formula (16) is used to... The amplitude is limited to avoid overcompensation. By calculating the reactive current and using inductive reactive compensation, the active power output on the grid side is limited, providing reactive power support to the grid to ensure DC-side voltage stability, thereby ensuring AC bus voltage stability.

[0120] Figure 4 is a flow chart of a control method of a flywheel energy storage micro-grid provided by another exemplary embodiment.

[0121] As shown in Figure 4 , the method comprises:

[0122] 1. detecting a grid voltage, and the grid voltage has a symmetric sudden rise fault;

[0123] 2. if , switching a grid-side control strategy, and the grid-side inverter preferentially outputs inductive reactive power to compensate for the grid, and U ref is the detected grid voltage;

[0124] 3. limiting when calculating the reactive current:

[0125] 4. if , U is the active current reference value, and at this time, the voltage outer loop can effectively stabilize the DC bus voltage;

[0126] 5. if or , controlling the flywheel energy storage array system to absorb the excess energy on the DC side until the grid voltage returns to the rated voltage;

[0127] 6. the flywheel energy storage array system finishes charging, and the system returns to steady-state operation.

[0128] Figure 5 is a schematic diagram of an active disturbance rejection controller provided by an exemplary embodiment. As shown in Figure 5 , the real-time detected DC bus voltage U dc and the predetermined reference voltage are subtracted, and then is obtained through the ADRC controller During high voltage ride through (HVRT), is calculated by formula and substituted into formula to obtain After the selector, the smaller value of and is selected to obtain and After the selector, the smaller value of and is selected to obtain and

[0129] After the PI controller, the dq and αβ coordinate conversion are performed, and then input to the space vector pulse width modulation (SVPWM). Figure 6 Based on the same inventive concept, the disclosure also provides a control device of a flywheel energy storage micro-grid.is a block diagram of a control device of a flywheel energy storage micro-grid provided by an example embodiment. As shown in Figure 6 The control device 600 of the flywheel energy storage micro-grid includes a detection module 601, a first control module 602, a second control module 603 and a third control module 604.

[0130] The detection module 601 is configured to detect an AC voltage in the power grid.

[0131] The first control module 602 is configured to control the grid-side converter to output reactive power to reduce the voltage on the DC bus if the AC voltage is in a first predetermined range.

[0132] The second control module 603 is configured to control the grid-side converter to output reactive power or control the flywheel energy storage sub-grid to increase the energy received from the DC bus to reduce the voltage on the DC bus if the AC voltage is in a second predetermined range.

[0133] The third control module 604 is configured to control the flywheel energy storage sub-grid to increase the energy received from the DC bus if the AC voltage is in a third predetermined range, wherein the voltage in the first predetermined range is greater than the rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

[0134] Optionally, the second control module 603 includes a first control submodule.

[0135] The first control submodule is configured to control the grid-side converter to output reactive power to reduce the voltage on the DC bus if the AC voltage is in the second predetermined range and satisfies

[0136] wherein,

[0137] is a reference value of the d-axis current of the grid-side converter when the AC voltage in the power grid is the rated voltage, is the rated voltage, U ref is the AC voltage in the power grid, i max is a maximum allowable current value of the grid-side converter, i N is a current rating of the point of common coupling, and |·| is an absolute value.

[0138] Optionally, the second control module 603 further includes a second control submodule.

[0139] The second control submodule is configured to control the flywheel energy storage sub-grid to increase the energy received from the DC bus to reduce the voltage on the DC bus according to the following formula if the AC voltage is in the second predetermined range and satisfies

[0140] ​​

[0141]

[0142] wherein, according to a target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied, is a target value of the q-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied.

[0143] Optionally, the first control module 602 or the second control module 603 is configured to control the reactive current output by the grid-side converter to satisfy the following condition:

[0144]

[0145] wherein, a reference value of the q-axis current of the grid-side converter when the AC voltage in the power grid is the rated voltage, is a current value of the reactive current output by the grid-side converter in the d-axis, is max a maximum allowed current value of the grid-side converter, |·| is an absolute value.

[0146] Optionally, the first control module 602 or the second control module 603 is configured to control the reactive current output by the grid-side converter to further satisfy the following condition:

[0147]

[0148] wherein, a current value of the reactive current output by the grid-side converter in the q-axis, is a rated voltage, is ref an AC voltage in the power grid, is N a current rated value of the grid-connected point.

[0149] As to the apparatus in the above-mentioned embodiments, the specific manner in which each module performs operations has been described in detail in the embodiments related to the method, and will not be described in detail here.

[0150] Through the technical scheme, if the AC voltage of the power grid is in a high voltage difference crossing period, the real-time power grid voltage is divided into two ranges, if it is in a lower voltage range (second predetermined range), then the output reactive power of the grid-side converter is controlled or the flywheel energy storage sub-grid is controlled to increase the energy received from the DC bus to reduce the DC bus voltage, if it is in a higher voltage range (third predetermined range), the flywheel energy storage sub-grid is controlled to increase the storage of energy to reduce the DC bus voltage, so as to restore the power grid voltage to steady state operation. In this way, the machine-side control and grid-side coordinated control of the flywheel energy storage micro-grid are realized in a short time, the stability of the power grid voltage is good, and the reliability is high.

[0151] The present disclosure also provides a non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the steps of the above method provided by the present disclosure.

[0152] The present disclosure also provides an electronic device comprising a memory and a processor, the memory having stored thereon a computer program; the processor configured to execute the computer program in the memory to implement the steps of the above method provided by the present disclosure.

[0153] Figure 7 is a block diagram of an electronic device 700 according to an example embodiment. As shown, the electronic device 700 can include a processor 701 and a memory 702. The electronic device 700 can also include one or more of a multimedia component 703, an input / output (I / O) interface 704, and a communication component 705. Figure 7

[0154] ​The processor 701 is configured to control overall operations of the electronic device 700 to complete all or part of the steps of the flywheel energy storage micro-grid control method described above. The memory 702 is configured to store various types of data to support the operations of the electronic device 700, which can include, for example, instructions for any application or method operating on the electronic device 700, and application-related data, such as contact data, sent and received messages, pictures, audio, video, and the like. The memory 702 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The multimedia component 703 can include a screen and an audio component. The screen can be, for example, a touch screen, and the audio component is configured to output and / or input audio signals. For example, the audio component can include a microphone configured to receive external audio signals. The received audio signals can be further stored in the memory 702 or transmitted through the communication component 705. The audio component also includes at least one speaker configured to output audio signals. The I / O interface 704 provides an interface between the processor 701 and other interface modules, which can be a keyboard, a mouse, a button, and the like. The buttons can be virtual buttons or physical buttons. The communication component 705 is configured to perform wired or wireless communication between the electronic device 700 and other devices. Wireless communication, such as Wi-Fi, Bluetooth, near field communication (NFC), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, and the like, or a combination of one or more of them, is not limited herein. Therefore, the corresponding communication component 705 can include a Wi-Fi module, a Bluetooth module, an NFC module, and the like.

[0155] In an exemplary embodiment, the electronic device 700 can be implemented by one or more Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor or other electronic elements for executing the control method of the flywheel energy storage micro-grid described above.

[0156] In another exemplary embodiment, a computer readable storage medium including program instructions is also provided, which when executed by a processor, implement the steps of the control method of the flywheel energy storage micro-grid described above. For example, the computer readable storage medium can be the memory 702 described above including program instructions, which can be executed by the processor 701 of the electronic device 700 to complete the control method of the flywheel energy storage micro-grid described above.

[0157] In another exemplary embodiment, a non-transitory computer program product is also provided, which contains a computer program capable of being executed by a programmable device, and the computer program has code portions for executing the control method of the flywheel energy storage micro-grid described above when executed by the programmable device.

[0158] The preferred embodiments of the present disclosure are described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above-described embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0159] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0160] Furthermore, any combination of the various different embodiments of the present disclosure can also be made, as long as it does not deviate from the idea of the present disclosure, and it should be considered as disclosed by the present disclosure.

Claims

1. A control method of a flywheel energy storage microgrid, characterized in that, The micro-grid comprises a flywheel energy storage sub-grid, a DC bus and a grid-side converter, the flywheel energy storage sub-grid is connected to the grid-side converter through the DC bus, and the grid-side converter is connected to a power grid. detecting an AC voltage in the power grid; if the AC voltage is in a first predetermined range, controlling the grid-side converter to output reactive power to reduce a voltage on the DC bus; if the AC voltage is in a second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase energy received from the DC bus to reduce the voltage on the DC bus; if the AC voltage is in a third predetermined range, controlling the flywheel energy storage sub-grid to increase energy received from the DC bus, wherein the voltage in the first predetermined range is greater than a rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

2. The method of claim 1, wherein, The if the AC voltage is in the second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase energy received from the DC bus to reduce the voltage on the DC bus comprises: if the AC voltage is in the second predetermined range and the net-side converter is controlled to output reactive power to reduce the voltage on the DC bus; wherein The reference value for the d-axis current of the grid-side converter when the AC voltage in the power grid is the rated voltage. When the AC voltage is within the second predetermined range and satisfies At that time, the target value of the d-axis current of the grid-side converter, When the AC voltage is within the second predetermined range and satisfies At that time, the target value of the q-axis current of the grid-side converter. The rated voltage, The AC voltage in the power grid is [missing information]. This is the maximum allowable current value of the grid-side converter. is the rated current at the grid connection point, and || is the absolute value.

3. The method of claim 2, wherein, The if the AC voltage is in the second predetermined range, controlling the grid-side converter to output reactive power or controlling the flywheel energy storage sub-grid to increase energy received from the DC bus to reduce the voltage on the DC bus further comprises: if the AC voltage is in the second predetermined range and then the flywheel energy storage subnetwork is controlled to increase the energy received from the DC bus to decrease the voltage on the DC bus according to the following equation: wherein, according to a target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied, is a target value of the q-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied.

4. The method of claim 1, wherein, The controlling the grid-side converter to output reactive power comprises controlling a reactive current output by the grid-side converter to satisfy the following condition: wherein is a reference value for the q-axis current of the grid-side converter when the alternating voltage in the grid is the rated voltage, is the current value of the reactive current output by the grid-side converter in the d-axis, is the maximum allowed current value of the grid-side converter, and || is the absolute value.

5. The method of claim 4, wherein, The controlling the grid-side converter to output reactive power comprises controlling a reactive current output by the grid-side converter to further satisfy the following condition: wherein is the current value of the reactive current in the q-axis output by the grid-side converter, is the rated voltage, is the AC voltage in the grid, is the current rating of the point of common coupling.

6. A control device of a flywheel energy storage microgrid, characterized in that, The micro-grid comprises a flywheel energy storage sub-grid, a DC bus and a grid-side converter, the flywheel energy storage sub-grid is connected to the grid-side converter through the DC bus, and the grid-side converter is connected to a power grid. a detecting module configured to detect an AC voltage in the power grid; a first control module configured to, if the AC voltage is in a first predetermined range, control the grid-side converter to output reactive power to reduce a voltage on the DC bus; a second control module configured to, if the AC voltage is in a second predetermined range, control the grid-side converter to output reactive power or control the flywheel energy storage sub-grid to increase energy received from the DC bus to reduce the voltage on the DC bus; a third control module configured to, if the AC voltage is in a third predetermined range, control the flywheel energy storage sub-grid to increase energy received from the DC bus, wherein the voltage in the first predetermined range is greater than a rated voltage of the power grid and less than the voltage in the second predetermined range, and the voltage in the second predetermined range is less than the voltage in the third predetermined range.

7. The apparatus of claim 6, wherein, The second control module comprises: a first control submodule configured to, if the AC voltage is in the second predetermined range and a first condition is satisfied, control the grid-side converter to output reactive power so as to reduce the voltage on the DC bus. wherein ; ； a reference value of the d-axis current of the grid-side converter when the AC voltage in the electrical grid is the rated voltage, a target value of the d-axis current of the grid-side converter when the AC voltage is in a second predetermined range and satisfies a target value of the d-axis current of the grid-side converter when the AC voltage is in a second predetermined range and satisfies the rated voltage, the AC voltage in the electrical grid, a maximum allowed current value of the grid-side converter, a current rating of the point of common coupling, and || is an absolute value.

8. The apparatus of claim 7, wherein, The second control module further comprises: a second control submodule configured to control the flywheel energy storage subnetwork to increase the energy received from the DC bus to decrease the voltage on the DC bus according to the following equation if the AC voltage is in the second predetermined range and the following conditions are met: a second control submodule configured to control the flywheel energy storage subnetwork to increase the energy received from the DC bus to decrease the voltage on the DC bus according to the following equation if the AC voltage is in the second predetermined range and the following conditions are met: wherein, according to a target value of the d-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied, is a target value of the q-axis current of the grid-side converter when the AC voltage is in the second predetermined range and the condition is satisfied.

9. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The program, when executed by a processor, implements the steps of the method of any one of claims 1-5.

10. An electronic device, comprising: comprising: a memory having a computer program stored thereon; a processor for executing the computer program in the memory to implement the steps of the method of any of claims 1-5.

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