Degaussing power supply system based on flywheel energy storage device

Abstract

The invention relates to a degaussing power supply system based on a flywheel energy storage device, and belongs to the technical field of pulse power supplies. The degaussing power supply system comprises a middle-high voltage feeder cabinet, a transformer, a network side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil, the middle-high voltage feeder cabinet is sequentially connected with the transformer, the grid-side rectifier, the four-quadrant DC / DC converter and the degaussing coil after outgoing; one or more flywheel energy storage devices are provided; all the flywheel energy storage devices are connected in parallel to the direct current side of the grid-side rectifier; each flywheel energy storage device comprises at least one flywheel motor, flywheel side converters with the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected with the bidirectional DC / DC converter through a flywheel side converter; the degaussing coil can provide required pulse working current for the high-power degaussing coil, meanwhile, the impact of the degaussing coil on a power grid during working is remarkably reduced, and the degaussing coil is easy to popularize and apply.

Description

Technical Field

[0001] The invention belongs to the technical field of pulse power supplies, and in particular relates to a demagnetization power supply system based on a flywheel energy storage device. Background Art

[0002] Due to the influence of the earth's magnetic field and stress, ships will gradually be magnetized during navigation and generate a fixed magnetic field. This magnetic field will remain for a long time and is not easy to dissipate, becoming a target for aerial and underwater magnetic field detection and an important source of threat from magnetic weapons. Implementing ship degaussing is an important measure to improve the ship's magnetic stealth capability.

[0003] During the degaussing process, a degaussing power supply is required to provide a large pulse current to the degaussing cable, thereby disrupting the magnetic domain distribution of the ship's hull and reducing magnetic field leakage. Existing degaussing power supplies usually use mains electricity or diesel generator sets to provide energy for the degaussing coil. Since the first pulse power of the degaussing current is relatively high, if the pulse power is all input from the mains electricity or diesel generator sets, it will have an impact on the mains electricity or diesel generator sets, bringing impact and harmonic pollution to the power grid, and is not conducive to the long-term stable operation of the power grid. Therefore, this degaussing power supply is mainly suitable for the degaussing of small and medium-sized ships.

[0004] To this end, some degaussing power supplies use batteries or supercapacitor energy storage devices to reduce the power demand for mains electricity and diesel generator sets. However, the battery power density is low and it is difficult to meet the instantaneous high power demand of the degaussing coil. The supercapacitor energy density is low and cannot provide enough power for the degaussing coil. If all supercapacitors are used for energy storage, the footprint of the power system will be greatly increased. In addition, the calendar life of batteries and supercapacitors is low, usually not exceeding 10 years, so the full life cost is high. In recent years, flywheel energy storage technology has developed rapidly, and some high-power flywheel energy storage devices have been put into use. The power density and energy density of flywheel energy storage are between batteries and supercapacitors, which can meet the power and energy requirements of the degaussing coil at the same time. Flywheel energy storage belongs to mechanical energy storage mode, with a life of up to 30 years and low full life cost. It is a major development trend of degaussing power supply in the future. Therefore, designing a degaussing power supply system based on flywheel energy storage device is of great significance for degaussing large ships. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of traditional degaussing power supplies, such as large impact on the power grid and high requirements for diesel generator sets, and to provide a degaussing power supply system based on flywheel energy storage, which can provide the required working current for the high-power degaussing working coil, reduce the impact of pulse power on the power grid, and reduce the requirements of the degaussing power supply for the diesel generator set.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A degaussing power supply system based on a flywheel energy storage device comprises a medium- and high-voltage feeder cabinet, a transformer, a grid-side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil; After the medium and high voltage feeder cabinet is connected, the transformer, grid-side rectifier, four-quadrant DC / DC converter and degaussing coil are connected in sequence; There are one or more flywheel energy storage devices; All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage device includes at least one flywheel motor, flywheel-side converters having the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power; Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power; The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power; Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil; Flywheel energy storage device, used to match the energy and power changes caused by sudden changes in the working state of the degaussing coil; Furthermore, the medium and high voltage feeder cabinets are used to access the mains or diesel generator sets.

[0007] Furthermore, the flywheel-side converter is used to rectify the three-phase AC power output by the flywheel motor into DC power; and is also used to invert the DC power output by the bidirectional DC / DC converter into three-phase AC power; Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0008] Furthermore, the grid-side rectifier adopts constant power mode control, and the specific method is as follows: According to the power command of the grid-side rectifier, the command value i of the d-axis current loop is calculated dref ; The command value i of the q-axis current loop qref Set to 0; After the grid current is transformed by the rotating coordinate system, the feedback values ​​of the d-axis and q-axis currents are obtained. d and i q ; The command value i of the d-axis current loop dref and the feedback value of the d-axis current i d After the error passes through the first PI controller, the d-axis component u of the grid voltage is superimposed gd and the d-axis decoupling component i of the output filter q ω0L, we get the d-axis modulation voltage u d; Wherein, ω0 is the fundamental angular frequency of the grid voltage, and L is the filter inductance value; The command value i of the q-axis current loop qref and the feedback value of the q-axis current i q After the error passes through the second PI controller, the q-axis component u of the grid voltage is superimposed gq and the q-axis decoupling component i of the output filter d ω0L, we get the q-axis modulation voltage u q ; Modulation voltage u d and u q After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abc , and then controls the on and off of the grid-side rectifier switching devices to achieve constant power mode control.

[0009] Furthermore, the four-quadrant DC / DC converter is used to control the waveform of the degaussing coil current. The specific method is as follows: Pulse current command i dcref The output current i of the four-quadrant DC / DC converter dc The error is passed through the third PI controller to obtain the output of current closed-loop control; The power of the degaussing coil is multiplied by the inverse of the maximum power of the degaussing coil, K, to obtain the per unit value x of the power of the degaussing coil; The output of the current closed loop control is multiplied by , the duty cycle d of the four-quadrant DC / DC converter is obtained; then the on-off of the switch device of the four-quadrant DC / DC converter is controlled to realize the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0010] Furthermore, the flywheel side converter charges and discharges the flywheel motor according to the demagnetization coil power. The specific method is as follows: In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted; The voltage outer loop control mode is: the flywheel side converter DC voltage command value U dcrefk The DC voltage U of the flywheel side converter dck After the error passes through the fourth PI controller, the feedforward current command value of the flywheel side converter is superimposed to obtain the command value i of the q-axis current inner loop qrefk ; The feedforward current command value of the flywheel side converter is obtained by dividing the demagnetization coil power by 1.5 times the AC side voltage amplitude of the flywheel side converter; The command value of the d-axis current inner loop i drefk Set to 0; The current inner loop control mode is: the sampled flywheel side converter output AC current is transformed by rotating coordinates to obtain the feedback value i of the d-axis and q-axis currents dk and i qk ; The command value i of the inner loop of the d-axis current drefk and the feedback value of the d-axis current i dk After the error passes through the fifth PI controller, the d-axis modulation voltage u is obtained. dk ; The command value i of the inner loop of the q-axis current qrefk and the feedback value of the q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ; Modulation voltage u dk and u qk After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switch device is controlled to realize the charging and discharging of the flywheel motor according to the demagnetization coil power.

[0011] Furthermore, the bidirectional DC / DC converter maintains the DC bus voltage constant, and the specific method is as follows: Adopting the control mode of DC voltage outer loop and current inner loop; The voltage outer loop control mode is: the demagnetization power supply DC bus voltage command value U dcref The DC voltage U of the bidirectional DC / DC converter dc After the error passes through the seventh PI controller, the feedforward current command value of the bidirectional DC / DC converter is superimposed to obtain the command value i of the current inner loop dcrefk ;The feedforward current command value of the bidirectional DC / DC converter is obtained by dividing the demagnetization coil power by the DC bus voltage; The current inner loop control mode is: the command value of the current inner loop i dcrefk The output current i of the bidirectional DC / DC converter dck The error is passed through the eighth PI controller to obtain the duty cycle d of the bidirectional DC / DC converter k , and then controls the on and off of the bidirectional DC / DC converter switching devices to maintain the constant DC bus voltage.

[0012] The present invention takes into account the rapid development of flywheel energy storage technology in recent years and its wide application in fields such as power grid frequency modulation and subway. Flywheel energy storage has a large power density and can quickly respond to sudden load changes, making it particularly suitable for use in demagnetization conditions. Therefore, a flywheel energy storage demagnetization power supply system is designed to reduce the adverse effects of pulse power on power grids or diesel generator sets, which has important engineering significance.

[0013] In the present invention, when the grid-side rectifier adopts constant power mode control, the phase of the rotating coordinate transformation and the reverse rotating coordinate transformation is obtained by phase-locking the grid voltage. When the flywheel-side converter charges and discharges the flywheel motor according to the demagnetization coil power, the phase of the rotating coordinate transformation and the reverse rotating coordinate transformation is obtained by the position sensor of the flywheel motor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The degaussing power supply system based on the flywheel energy storage device provided by the present invention can effectively reduce the capacity requirement of the power supply system for the power grid or the diesel generator by smoothing the pulse power of the degaussing coil of the flywheel energy storage device, avoid the impact of the pulse power on the power grid and the diesel generator set, and improve the power supply quality of the power supply system. Compared with lithium batteries and super-capacity energy storage degaussing power supplies, the flywheel energy storage device has a longer service life, a lower system life cycle cost, and higher safety; at the same time, the number of flywheel energy storage devices can be freely increased or decreased according to the degaussing coil, which increases the redundancy and flexibility of the system and effectively improves the safety and reliability of the power supply system; in addition, the flywheel energy storage device is connected in parallel to the DC bus, which is different from the traditional AC The grid-connected mode greatly enhances the system operation stability, and after passing through the DC bus, the grid-side rectifier, the four-quadrant DC / DC converter and the bidirectional DC / DC converter are decoupled, which greatly simplifies the control algorithm of the power supply system. In particular, when multiple demagnetization power supplies are connected to the strongly coupled demagnetization coil, the demagnetization currents of each channel need to run synchronously. At this time, only the four-quadrant DC / DC converter will be affected by the mutual inductance coupling of the demagnetization coil. The control algorithm of the grid-side rectifier and the bidirectional DC / DC converter is completely consistent with that of the single-channel power supply, and the difficulty of demagnetization current control is significantly reduced. In summary, the demagnetization power supply system based on the flywheel energy storage device proposed in the present invention is easy to implement in engineering and can promote the popularization and application of high-power demagnetization power supplies. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the topological structure of a demagnetization power supply system based on a flywheel energy storage device of the present invention; Figure 2 This is a control block diagram of the grid-side rectifier of the present invention; Figure 3 It is a control block diagram of a four-quadrant DC / DC converter of the present invention; Figure 4 This is a control block diagram of the flywheel side converter of the present invention; Figure 5 This is a control block diagram of a bidirectional DC / DC converter of the present invention; Figure 6 A topological diagram of a demagnetization power supply system based on a flywheel energy storage device in an application example of the present invention; Figure 7 It is a schematic diagram of the topology of the grid-side rectifier in the application example of the present invention; Figure 8 A schematic diagram of a topology of a four-quadrant DC / DC converter in an application example of the present invention; Fig. 9 A schematic diagram of a bidirectional DC / DC converter topology in an application example of the present invention; Fig.10 It is a schematic diagram of the flywheel side converter topology in an application example of the present invention; Fig.11 It is the simulation waveform of the degaussing coil current in the application example of the present invention; Fig.12 It is a simulation waveform of the output power of the flywheel energy storage device in the application example of the present invention; Fig.13 It is the simulated waveform of the power grid output power in the application example of the present invention; Fig.14 This is a DC bus voltage simulation waveform in an application example of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with embodiments.

[0017] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0018] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" to another element, it may be directly connected to the other element, or there may be intermediate elements. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0019] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two. The terms "inside", "upper", "lower", etc., indicating positions or state relationships, are based on the positions or state relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operate in a specific position, and therefore cannot be understood as limiting the present invention.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "provided with" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention will be understood according to specific circumstances.

[0021] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0022] Example 1

[0023] like Figure 1 As shown, a degaussing power supply system based on a flywheel energy storage device includes a medium and high voltage feeder cabinet, a transformer, a grid-side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil; After the medium and high voltage feeder cabinet is connected, the transformer, grid-side rectifier, four-quadrant DC / DC converter and degaussing coil are connected in sequence; There are one or more flywheel energy storage devices; All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage device includes at least one flywheel motor, flywheel-side converters having the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power; Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power; The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power; Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil;

[0024] The flywheel energy storage device is used to match the energy and power changes caused by sudden changes in the working state of the demagnetization coil.

[0025] Example 2 like Figure 1As shown, a degaussing power supply system based on a flywheel energy storage device includes a medium and high voltage feeder cabinet, a transformer, a grid-side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil; After the medium and high voltage feeder cabinet is connected, the transformer, grid-side rectifier, four-quadrant DC / DC converter and degaussing coil are connected in sequence; There are one or more flywheel energy storage devices; All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage device includes at least one flywheel motor, flywheel-side converters having the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power; Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power; The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power; Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil; The flywheel energy storage device is used to match the energy and power changes caused by sudden changes in the working state of the demagnetization coil.

[0026] Medium and high voltage feeder cabinets are used to access the mains or diesel generator sets.

[0027] The flywheel-side converter is used to rectify the three-phase AC power output by the flywheel motor into DC power; it is also used to invert the DC power output by the bidirectional DC / DC converter into three-phase AC power; Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0028] like Figure 2 As shown, the grid-side rectifier adopts constant power mode control, the specific method is: According to the power command of the grid-side rectifier, the command value i of the d-axis current loop is calculated dref ; The command value i of the q-axis current loop qref Set to 0; After the grid current is transformed by the rotating coordinate system, the feedback values ​​of the d-axis and q-axis currents are obtained. d and i q ; The command value i of the d-axis current loop dref and the feedback value of the d-axis current i d After the error passes through the first PI controller, the d-axis component u of the grid voltage is superimposed gd and the d-axis decoupling component i of the output filter q ω0L, we get the d-axis modulation voltage u d; Wherein, ω0 is the fundamental angular frequency of the grid voltage, and L is the filter inductance value; The command value i of the q-axis current loop qref and the feedback value of the q-axis current i q After the error passes through the second PI controller, the q-axis component u of the grid voltage is superimposed gq and the q-axis decoupling component i of the output filter d ω0L, we get the q-axis modulation voltage u q ; Modulation voltage u d and u q After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abc , and then controls the on and off of the grid-side rectifier switching devices to achieve constant power mode control.

[0029] like Figure 3 As shown, the four-quadrant DC / DC converter is used to control the waveform of the degaussing coil current. The specific method is: Pulse current command i dcref The output current i of the four-quadrant DC / DC converter dc The error is passed through the third PI controller to obtain the output of current closed-loop control; The power of the degaussing coil is multiplied by the inverse of the maximum power of the degaussing coil, K, to obtain the per unit value x of the power of the degaussing coil; The output of the current closed loop control is multiplied by , the duty cycle d of the four-quadrant DC / DC converter is obtained; then the on-off of the switch device of the four-quadrant DC / DC converter is controlled to realize the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0030] like Figure 4 As shown, the flywheel side converter charges and discharges the flywheel motor according to the demagnetization coil power. The specific method is: In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted; The voltage outer loop control mode is: the flywheel side converter DC voltage command value U dcrefk The DC voltage U of the flywheel side converter dck After the error passes through the fourth PI controller, the feedforward current command value of the flywheel side converter is superimposed to obtain the command value i of the q-axis current inner loop qrefk ; The feedforward current command value of the flywheel side converter is obtained by dividing the demagnetization coil power by 1.5 times the AC side voltage amplitude of the flywheel side converter; The command value of the d-axis current inner loop i drefk Set to 0; The current inner loop control mode is: the sampled flywheel side converter output AC current is transformed by rotating coordinates to obtain the feedback value i of the d-axis and q-axis currentsdk and i qk ; The command value i of the inner loop of the d-axis current drefk and the feedback value of the d-axis current i dk After the error passes through the fifth PI controller, the d-axis modulation voltage u is obtained. dk ; The command value i of the q-axis current inner loop qrefk and the feedback value of the q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ; Modulation voltage u dk and u qk After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switch device is controlled to realize the charging and discharging of the flywheel motor according to the demagnetization coil power.

[0031] like Figure 5 As shown, the bidirectional DC / DC converter maintains the DC bus voltage constant, and the specific method is: Adopting the control mode of DC voltage outer loop and current inner loop; The voltage outer loop control mode is: the demagnetization power supply DC bus voltage command value U dcref The DC voltage U of the bidirectional DC / DC converter dc After the error passes through the seventh PI controller, the feedforward current command value of the bidirectional DC / DC converter is superimposed to obtain the command value i of the current inner loop dcrefk ;The feedforward current command value of the bidirectional DC / DC converter is obtained by dividing the demagnetization coil power by the DC bus voltage; The current inner loop control mode is: the command value of the current inner loop i dcrefk The output current i of the bidirectional DC / DC converter dck The error is passed through the eighth PI controller to obtain the duty cycle d of the bidirectional DC / DC converter k , and then controls the on and off of the bidirectional DC / DC converter switching devices to maintain the constant DC bus voltage.

[0032] Example 3 like Figure 1 As shown, a degaussing power supply system based on a flywheel energy storage device includes a medium and high voltage feeder cabinet, a transformer, a grid-side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil; After the medium and high voltage feeder cabinet is connected, the transformer, grid-side rectifier, four-quadrant DC / DC converter and degaussing coil are connected in sequence; There are one or more flywheel energy storage devices; All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage device includes at least one flywheel motor, flywheel-side converters having the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power; Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power; The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power; Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil; The flywheel energy storage device is used to match the energy and power changes caused by sudden changes in the working state of the demagnetization coil.

[0033] Medium and high voltage feeder cabinets are used to access the mains or diesel generator sets.

[0034] The flywheel-side converter is used to rectify the three-phase AC power output by the flywheel motor into DC power; it is also used to invert the DC power output by the bidirectional DC / DC converter into three-phase AC power; Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0035] like Figure 2 As shown, the grid-side rectifier adopts constant power mode control, the specific method is: According to the power command of the grid-side rectifier, the command value i of the d-axis current loop is calculated dref ; The command value i of the q-axis current loop qref Set to 0; After the grid current is transformed by the rotating coordinate system, the feedback values ​​of the d-axis and q-axis currents are obtained. d and i q ; The command value i of the d-axis current loop dref and the feedback value of the d-axis current i d After the error passes through the first PI controller, the d-axis component u of the grid voltage is superimposed gd and the d-axis decoupling component i of the output filter q ω0L, we get the d-axis modulation voltage u d ; Wherein, ω0 is the fundamental angular frequency of the grid voltage, and L is the filter inductance value; ; in, represents the first PI controller, k p1 and k i1 represent the proportional parameter and integral parameter of the first PI controller respectively; The command value i of the q-axis current loop qref and the feedback value of the q-axis current i q After the error passes through the second PI controller, the q-axis component u of the grid voltage is superimposed gq and the q-axis decoupling component i of the output filter d ω0L, we get the q-axis modulation voltage u q ; ; in, represents the second PI controller, k p2 and k i2 represent the proportional parameter and integral parameter of the second PI controller respectively; Modulation voltage u d and u q After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abc , and then controls the on and off of the grid-side rectifier switching devices to achieve constant power mode control.

[0036] like Figure 3 As shown, the four-quadrant DC / DC converter is used to control the waveform of the degaussing coil current. The specific method is: Pulse current command i dcref The output current i of the four-quadrant DC / DC converter dc The error is passed through the third PI controller to obtain the output of current closed-loop control; The power of the degaussing coil is multiplied by the inverse of the maximum power of the degaussing coil, K, to obtain the per unit value x of the power of the degaussing coil; The output of the current closed loop control is multiplied by , the duty cycle d of the four-quadrant DC / DC converter is obtained; then the on-off of the switch device of the four-quadrant DC / DC converter is controlled to realize the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0037] ; in, represents the third PI controller, k p3 and k i3 represent the proportional parameter and integral parameter of the third PI controller respectively.

[0038] like Figure 4 As shown, the flywheel side converter charges and discharges the flywheel motor according to the demagnetization coil power. The specific method is: In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted; The voltage outer loop control mode is: the flywheel side converter DC voltage command value U dcrefk The DC voltage U of the flywheel side converterdck After the error passes through the fourth PI controller, the feedforward current command value of the flywheel side converter is superimposed to obtain the command value i of the q-axis current inner loop qrefk ; The feedforward current command value of the flywheel side converter is obtained by dividing the demagnetization coil power by 1.5 times the AC side voltage amplitude of the flywheel side converter; The command value of the d-axis current inner loop i drefk Set to 0; ; in, represents the fourth PI controller, k p4 and k i4 represent the proportional parameter and integral parameter of the fourth PI controller respectively.

[0039] The current inner loop control mode is: the sampled flywheel side converter output AC current is transformed by rotating coordinates to obtain the feedback value i of the d-axis and q-axis currents dk and i qk ; The command value i of the inner loop of the d-axis current drefk and the feedback value of the d-axis current i dk After the error passes through the fifth PI controller, the d-axis modulation voltage u is obtained. dk ; ; in, represents the fifth PI controller, k p5 and k i5 denote the proportional parameter and the integral parameter of the fifth PI controller respectively; The command value i of the inner loop of the q-axis current qrefk and the feedback value of the q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ; ; in, represents the sixth PI controller, k p6 and k i6 denote the proportional parameter and the integral parameter of the sixth PI controller respectively; Modulation voltage u dk and u qk After the inverse coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switch device is controlled to realize the charging and discharging of the flywheel motor according to the demagnetization coil power.

[0040] like Figure 5 As shown, the bidirectional DC / DC converter maintains the DC bus voltage constant, and the specific method is: Adopting the control mode of DC voltage outer loop and current inner loop; The voltage outer loop control mode is: the demagnetization power supply DC bus voltage command value U dcref The DC voltage U of the bidirectional DC / DC converter dc After the error passes through the seventh PI controller, the feedforward current command value of the bidirectional DC / DC converter is superimposed to obtain the command value i of the current inner loop dcrefk ;The feedforward current command value of the bidirectional DC / DC converter is obtained by dividing the demagnetization coil power by the DC bus voltage; ; in, represents the seventh PI controller, k p7 and k i7 denote the proportional parameter and the integral parameter of the seventh PI controller respectively; The current inner loop control mode is: the command value of the current inner loop i dcrefk The output current i of the bidirectional DC / DC converter dck The error is passed through the eighth PI controller to obtain the duty cycle d of the bidirectional DC / DC converter k , and then controls the on and off of the bidirectional DC / DC converter switching devices to maintain the constant DC bus voltage.

[0041]

[0042] in, represents the eighth PI controller, k p8 and k i8 They represent the proportional parameter and integral parameter of the eighth PI controller respectively.

[0043] Application Examples Assume that the resistance of the degaussing coil is 0.2Ω and the inductance is 0.01H. Figure 6 The demagnetization power supply system topology based on the flywheel energy storage device is shown in the figure, where the transformer ratio is 10kV / 0.69kV; the grid-side rectifier adopts bridge PWM rectification, and its topology is shown in Figure 7 , the DC side output voltage is 2500V; the output voltage of the four-quadrant DC / DC converter is adjustable between 4~2200V, and the output current range is between 40~4500A. Its topology refers to Figure 8 ; A total of 5 flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier. Each flywheel energy storage device includes a flywheel motor, a flywheel-side rectifier and a bidirectional DC / DC converter. The flywheel motor output is connected to the flywheel-side rectifier, and then connected to the DC side of the grid-side rectifier through a bidirectional DC / DC converter. The topology of the bidirectional DC / DC converter can be found in Fig. 9 ; The flywheel side rectifier outputs a DC voltage of 1200V. Its topology is shown in Fig.10 .

[0044] Through Matlab / Simulink circuit simulation, the working current of the degaussing coil is two alternating pulse waveforms. The positive pulse current amplitude is 4500A, the current pulse is turned on for 1s, and the current pulse is turned off for 3s; the negative pulse current amplitude is 4300A, the current pulse is turned on for 5s, and the current pulse is turned off for 7s. The simulated current waveform of the degaussing coil is as follows: Fig.11 As shown in the figure, the simulation current accuracy is about 0.17%, which meets the requirements of demagnetization conditions. The output power simulation waveform of the flywheel energy storage device is as follows: Fig.12 As shown in the figure, during the period when the degaussing coil pulse current is off, the flywheel energy storage device absorbs power from the grid side to store energy, and during the period when the degaussing coil current pulse is on, the flywheel energy storage device provides power to the coil. The power simulation waveform on the grid side is shown in the figure. Fig.13 As shown in the figure, it can be seen that during the process of opening and closing the pulse current of the degaussing coil, the power on the grid side remains basically constant, indicating that the pulse current has no impact on the grid, and the power generated by the sudden addition and removal of the degaussing coil is smoothed by the flywheel energy storage device. Fig.14 As shown, the DC bus voltage fluctuates around 2500V, with little overall change.

[0045] In summary, the flywheel energy storage demagnetization power supply proposed in the present invention can meet the power supply demand of the demagnetization working coil, and at the same time smooth the power impact of the working coil on the power grid or diesel generator set during the demagnetization operation.

[0046] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A demagnetization power supply system based on a flywheel energy storage device, characterized in that: It includes medium and high voltage feeder cabinets, transformers, grid-side rectifiers, four-quadrant DC / DC converters, flywheel energy storage devices and degaussing coils; After the medium and high voltage feeder cabinet is connected, the transformer, grid-side rectifier, four-quadrant DC / DC converter and degaussing coil are connected in sequence; There are one or more flywheel energy storage devices; All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage device includes at least one flywheel motor, flywheel-side converters having the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power; Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power; The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power; Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil; The flywheel energy storage device is used to match the energy and power changes caused by sudden changes in the working state of the demagnetization coil.

2. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: Medium and high voltage feeder cabinets are used to access the mains or diesel generator sets.

3. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: The flywheel-side converter is used to rectify the three-phase AC power output by the flywheel motor into DC power; it is also used to invert the DC power output by the bidirectional DC / DC converter into three-phase AC power; Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

4. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: The grid-side rectifier adopts constant power mode control, the specific method is: According to the power command of the grid-side rectifier, the command value of the d-axis current loop is calculated i dref ; The command value of the q-axis current loop i qref Set to 0; The grid current is transformed by rotating coordinates to obtain the feedback values ​​of the d-axis and q-axis currents. i d and i q ; D-axis current loop command value i dref and the feedback value of the d-axis current i d After the error passes through the first PI controller, the d-axis component of the grid voltage is superimposed u gd and the d-axis decoupling component of the output filter i q ω 0 L , and the d-axis modulation voltage is obtained u d ; in, ω 0 is the fundamental angular frequency of the grid voltage, L is the filter inductance value; The command value of the q-axis current loop i qref and the feedback value of the q-axis current i q After the error passes through the second PI controller, the q-axis component of the grid voltage is superimposed u gq and the q-axis decoupling component of the output filter i d ω 0 L , and the q-axis modulation voltage is obtained u q ; Modulation voltage u d and u q After the inverse rotation coordinate transformation, the three-phase AC modulation voltage is obtained u abc , and then controls the on and off of the grid-side rectifier switching devices to achieve constant power mode control.

5. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: The four-quadrant DC / DC converter is used to control the waveform of the degaussing coil current. The specific method is as follows: Pulse current command i dcref The output current of the four-quadrant DC / DC converter i dc The error is passed through the third PI controller to obtain the output of current closed-loop control; The power of the degaussing coil multiplied by the inverse of the maximum power of the degaussing coil K , get the per unit value of the degaussing coil power x ; The output of the current closed loop control is multiplied by , and the duty cycle of the four-quadrant DC / DC converter is obtained d ; Then the on and off of the four-quadrant DC / DC converter switching device is controlled to achieve the current waveform control of the degaussing coil and limit the power of the degaussing coil.

6. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: The flywheel side converter charges and discharges the flywheel motor according to the demagnetization coil power. The specific method is: In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted; The voltage outer loop control mode is: the DC voltage command value of the flywheel side converter U dcrefk The DC voltage of the flywheel side converter U dck After the error passes through the fourth PI controller, the feedforward current command value of the flywheel side converter is superimposed to obtain the command value of the q-axis current inner loop i qrefk ; The feedforward current command value of the flywheel side converter is obtained by dividing the demagnetization coil power by 1.5 times the AC side voltage amplitude of the flywheel side converter; The command value of the d-axis current inner loop i drefk Set to 0; The current inner loop control mode is: the sampled flywheel side converter output AC current is transformed into the feedback value of the d-axis and q-axis current after the rotation coordinate transformation i dk and i qk ; D-axis current inner loop command value i drefk and the feedback value of the d-axis current i dk After the error passes through the fifth PI controller, the d-axis modulation voltage is obtained. u dk ; The command value of the q-axis current inner loop i qrefk and the feedback value of the q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage is obtained. u qk ; Modulation voltage u dk and u qk After the inverse rotation coordinate transformation, the three-phase AC modulation voltage is obtained u abck ; Then the on and off of the flywheel side rectifier switch device is controlled to realize the charging and discharging of the flywheel motor according to the demagnetization coil power.

7. The degaussing power supply system based on the flywheel energy storage device according to claim 1, characterized in that: The bidirectional DC / DC converter maintains the DC bus voltage constant by: Adopting the control mode of DC voltage outer loop and current inner loop; The voltage outer loop control mode is: demagnetization power supply DC bus voltage command value U dcref With bidirectional DC / DC converter DC voltage U dc After the error passes through the seventh PI controller, the feedforward current command value of the bidirectional DC / DC converter is superimposed to obtain the command value of the current inner loop i dcrefk ;The feedforward current command value of the bidirectional DC / DC converter is obtained by dividing the demagnetization coil power by the DC bus voltage; The current inner loop control mode is: the command value of the current inner loop i dcrefk Bidirectional DC / DC converter output current i dck The error is passed through the eighth PI controller to obtain the duty cycle of the bidirectional DC / DC converter d k , and then controls the on and off of the bidirectional DC / DC converter switching devices to maintain the constant DC bus voltage.

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