A demagnetization power supply system based on flywheel energy storage device

Abstract

The present invention relates to a degaussing power supply system based on a flywheel energy storage device, belonging to the field of pulse power supply technology. The degaussing power supply system 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 to the transformer, the grid-side rectifier, the four-quadrant DC / DC converter, and the degaussing coil 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, the same number of flywheel-side converters as the number of flywheel motors, and also includes a bidirectional DC / DC converter; each flywheel motor is connected to the bidirectional DC / DC converter via a flywheel-side converter; the present invention can provide the required pulse operating current for the high-power degaussing coil, while significantly reducing the impact of the degaussing coil on the power grid during operation, and is easy to promote and apply.

Description

Technical Field

[0001] The present 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 last 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 demagnetization is an important measure to improve the ship's magnetic stealth capability.

[0003] During the degaussing process, a degaussing power supply is required to supply a high pulse current to the degaussing cable, disrupting the magnetic domain distribution of the ship's hull and reducing magnetic field leakage. Existing degaussing power supplies typically utilize mains electricity or diesel generators to power the degaussing coils. Because the first pulse of the degaussing current has a high power, if all the pulse power is supplied by the mains or diesel generators, it will impact the mains or diesel generators, causing shock and harmonic pollution to the power grid, and hindering the long-term stable operation of the grid. Therefore, this type of degaussing power supply is primarily suitable for degaussing small and medium-sized ships.

[0004] To this end, some degaussing power supplies use batteries or supercapacitors to reduce the power demand from the mains and diesel generators. However, batteries have low power density and cannot meet the instantaneous high power demands of the degaussing coils. Supercapacitors, on the other hand, have low energy density and cannot provide sufficient energy for the degaussing coils. If all supercapacitors were used for energy storage, the power system's footprint would increase significantly. Furthermore, batteries and supercapacitors have short calendar lives, typically less than 10 years, resulting in high lifecycle costs. In recent years, flywheel energy storage technology has developed rapidly, and some high-power flywheel energy storage devices have been put into use. Flywheel energy storage has a power and energy density between those of batteries and supercapacitors, capable of meeting both the power and energy demands of the degaussing coils. Furthermore, flywheel energy storage is a mechanical energy storage method with a lifespan of up to 30 years. This low lifecycle cost makes it a major development trend in future degaussing power supplies. Therefore, designing a degaussing power supply system based on flywheel energy storage is of great significance for the degaussing of 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 high-power degaussing working coils, reduce the impact of pulse power on the power grid, and lower the requirements of the degaussing power supply for diesel generator sets.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] 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;

[0008] 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;

[0009] There are one or more flywheel energy storage devices;

[0010] All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier;

[0011] Each flywheel energy storage device includes at least one flywheel motor, the same number of flywheel-side converters 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;

[0012] Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power;

[0013] Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power;

[0014] The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power;

[0015] Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil;

[0016] Flywheel energy storage device, used to match the energy and power changes caused by sudden changes in the working state of the degaussing coil;

[0017] Furthermore, the medium and high voltage feeder cabinet is used to access the mains or diesel generator set.

[0018] 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;

[0019] Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0020] Furthermore, the grid-side rectifier adopts constant power mode control, and the specific method is as follows:

[0021] According to the power instruction of the grid-side rectifier, the instruction 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;

[0022] After the grid current is transformed into the rotating coordinate, the feedback value i of the d-axis and q-axis current is obtained. d and i q ;

[0023] 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, 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;

[0024] The command value i of the q-axis current loop qref and the feedback value of 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 ;

[0025] Modulation voltage u d and u q After the inverse rotation 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.

[0026] Furthermore, a four-quadrant DC / DC converter is used to control the waveform of the degaussing coil current. The specific method is as follows:

[0027] Pulse current command i dcref The output current i of the four-quadrant DC / DC converter is dc The error is passed through the third PI controller to obtain the output of current closed-loop control;

[0028] 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;

[0029] 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 switching device of the four-quadrant DC / DC converter is controlled to achieve the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0030] Furthermore, the flywheel-side converter charges and discharges the flywheel motor according to the power of the demagnetization coil. The specific method is as follows:

[0031] In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted;

[0032] The voltage outer loop control mode is: the flywheel side converter DC voltage command value U dcrefkThe 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;

[0033] 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 i after the rotation coordinate transformation dk and i qk ;

[0034] 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 ;

[0035] The command value i of the q-axis current inner loop qrefk and the feedback value of q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ;

[0036] Modulation voltage u dk and u qk After the inverse rotation coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switching device is controlled to realize the charging and discharging of the flywheel motor according to the power of the demagnetization coil.

[0037] Furthermore, the bidirectional DC / DC converter maintains the DC bus voltage constant by:

[0038] Adopting the control mode of DC voltage outer loop and current inner loop;

[0039] The voltage outer loop control mode is: demagnetization power supply DC bus voltage command value U dcref and 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 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.

[0040] The current inner loop control mode is: the current inner loop command value i dcrefk and the bidirectional DC / DC converter output current i dckThe 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] 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 subways. Flywheel energy storage has a high 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.

[0042] In the present invention, when the grid-side rectifier is controlled in constant power mode, the phases of the rotating coordinate transformation and the reverse rotating coordinate transformation are obtained by phase-locking the grid voltage. When the flywheel-side converter charges and discharges the flywheel motor based on the power of the demagnetization coil, the phases of the rotating coordinate transformation and the reverse rotating coordinate transformation are obtained by the flywheel motor's position sensor.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a degaussing power supply system based on a flywheel energy storage device. By smoothing the pulse power of the degaussing coil through the flywheel energy storage device, the capacity requirement of the power supply system for the power grid or the diesel generator can be effectively reduced, the impact of the pulse power on the power grid and the diesel generator set can be avoided, and the power supply quality of the power supply system can be improved. Compared with lithium batteries and super-capacity energy storage degaussing power supplies, the flywheel energy storage device has a longer service life, 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, four-quadrant DC / DC converter and 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 a single 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

[0045] Figure 1 A schematic diagram of the topological structure of the demagnetization power supply system based on the flywheel energy storage device of the present invention;

[0046] Figure 2 This is a control block diagram of the grid-side rectifier of the present invention;

[0047] Figure 3 This is a control block diagram of a four-quadrant DC / DC converter according to the present invention;

[0048] Figure 4 This is a control block diagram of the flywheel-side converter of the present invention;

[0049] Figure 5 This is a control block diagram of a bidirectional DC / DC converter according to the present invention;

[0050] Figure 6 Schematic diagram of the topology of a demagnetization power supply system based on a flywheel energy storage device in an application example of the present invention;

[0051] Figure 7 Schematic diagram of the topology of the grid-side rectifier in an application example of the present invention;

[0052] Figure 8 Schematic diagram of the topology of a four-quadrant DC / DC converter in an application example of the present invention;

[0053] Figure 9 Schematic diagram of the topology of a bidirectional DC / DC converter in an application example of the present invention;

[0054] Figure 10 Schematic diagram of the flywheel-side converter topology in an application example of the present invention;

[0055] Figure 11 This is the simulated waveform of the degaussing coil current in the application example of the present invention;

[0056] Figure 12 The simulated waveform of the output power of the flywheel energy storage device in the application example of the present invention;

[0057] Figure 13 This is the simulated waveform of the power grid output power in the application example of the present invention;

[0058] Figure 14 This is the DC bus voltage simulation waveform in the application example of the present invention. DETAILED DESCRIPTION

[0059] The present invention is described in further detail below with reference to the embodiments.

[0060] Those skilled in the art will understand that the following examples are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in the product specifications were used. Materials or equipment used without manufacturer identification are commercially available conventional products.

[0061] It will be understood by those skilled in the art that, unless otherwise 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 say that an element is "connected" to another element, it can 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.

[0062] In the description of the present invention, unless otherwise specified, "plurality" means two or more. Terms such as "inner," "upper," and "lower" indicating positions or states are based on those shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention.

[0063] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "provided with" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0064] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, will not be interpreted in an idealized or overly formal sense.

[0065] Example 1

[0066] 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;

[0067] 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;

[0068] There are one or more flywheel energy storage devices;

[0069] All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier;

[0070] Each flywheel energy storage device includes at least one flywheel motor, the same number of flywheel-side converters 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;

[0071] Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power;

[0072] Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power;

[0073] The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power;

[0074] Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil;

[0075] 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.

[0076] Example 2

[0077] 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;

[0078] 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;

[0079] There are one or more flywheel energy storage devices;

[0080] All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier;

[0081] Each flywheel energy storage device includes at least one flywheel motor, the same number of flywheel-side converters 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;

[0082] Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power;

[0083] Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power;

[0084] The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power;

[0085] Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil;

[0086] 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.

[0087] Medium and high voltage feeder cabinets are used to access mains power or diesel generator sets.

[0088] 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;

[0089] Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0090] like Figure 2 As shown, the grid-side rectifier adopts constant power mode control, the specific method is:

[0091] According to the power instruction of the grid-side rectifier, the instruction 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;

[0092] After the grid current is transformed into the rotating coordinate, the feedback value i of the d-axis and q-axis current is obtained. d and i q ;

[0093] 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, 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;

[0094] The command value i of the q-axis current loop qref and the feedback value of 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 ;

[0095] Modulation voltage u d and u q After the inverse rotation 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.

[0096] 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 as follows:

[0097] Pulse current command i dcref The output current i of the four-quadrant DC / DC converter is dc The error is passed through the third PI controller to obtain the output of current closed-loop control;

[0098] 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;

[0099] 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 switching device of the four-quadrant DC / DC converter is controlled to achieve the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0100] like Figure 4 As shown, the flywheel-side converter charges and discharges the flywheel motor according to the power of the demagnetization coil. The specific method is:

[0101] In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted;

[0102] 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;

[0103] 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 i after the rotation coordinate transformation dk and i qk ;

[0104] 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 ;

[0105] The command value i of the q-axis current inner loop qrefk and the feedback value of q-axis current i qkAfter the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ;

[0106] Modulation voltage u dk and u qk After the inverse rotation coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switching device is controlled to realize the charging and discharging of the flywheel motor according to the power of the demagnetization coil.

[0107] like Figure 5 As shown in Figure 1, the bidirectional DC / DC converter maintains the DC bus voltage constant by:

[0108] Adopting the control mode of DC voltage outer loop and current inner loop;

[0109] The voltage outer loop control mode is: demagnetization power supply DC bus voltage command value U dcref and 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 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.

[0110] The current inner loop control mode is: the current inner loop command value i dcrefk and the bidirectional DC / DC converter output current i 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.

[0111] Example 3

[0112] 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;

[0113] 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;

[0114] There are one or more flywheel energy storage devices;

[0115] All flywheel energy storage devices are connected in parallel to the DC side of the grid-side rectifier;

[0116] Each flywheel energy storage device includes at least one flywheel motor, the same number of flywheel-side converters 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;

[0117] Among them, the medium and high voltage feeder cabinet is used to access three-phase medium and high voltage AC power;

[0118] Transformers are used to reduce medium and high voltage three-phase AC power to low voltage AC power;

[0119] The grid-side rectifier is used to rectify three-phase low-voltage AC power into DC power;

[0120] Four-quadrant DC / DC converter, used to control the alternating pulse current waveform of the degaussing coil;

[0121] 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.

[0122] Medium and high voltage feeder cabinets are used to access mains power or diesel generator sets.

[0123] 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;

[0124] Bidirectional DC / DC converters are used for voltage conversion between different DC voltages.

[0125] like Figure 2 As shown, the grid-side rectifier adopts constant power mode control, the specific method is:

[0126] According to the power instruction of the grid-side rectifier, the instruction 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;

[0127] After the grid current is transformed into the rotating coordinate, the feedback value i of the d-axis and q-axis current is obtained. d and i q ;

[0128] 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, 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;

[0129] ;

[0130] in, represents the first PI controller, k p1 and k i1 represent the proportional parameter and integral parameter of the first PI controller respectively;

[0131] The command value i of the q-axis current loop qref and the feedback value of 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 ;

[0132] ;

[0133] in, represents the second PI controller, k p2 and k i2 represent the proportional parameter and integral parameter of the second PI controller respectively;

[0134] Modulation voltage u d and u q After the inverse rotation 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.

[0135] 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 as follows:

[0136] Pulse current command i dcref The output current i of the four-quadrant DC / DC converter is dc The error is passed through the third PI controller to obtain the output of current closed-loop control;

[0137] 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;

[0138] 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 switching device of the four-quadrant DC / DC converter is controlled to achieve the current waveform control of the degaussing coil and limit the power of the degaussing coil.

[0139] ;

[0140] in, represents the third PI controller, k p3and k i3 represent the proportional parameter and integral parameter of the third PI controller respectively.

[0141] like Figure 4 As shown, the flywheel-side converter charges and discharges the flywheel motor according to the power of the demagnetization coil. The specific method is:

[0142] In the rotating coordinate system, the voltage outer loop control mode and the current inner loop control mode are adopted;

[0143] 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;

[0144] ;

[0145] in, represents the fourth PI controller, k p4 and k i4 represent the proportional parameter and integral parameter of the fourth PI controller respectively.

[0146] 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 i after the rotation coordinate transformation dk and i qk ;

[0147] 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 ;

[0148] ;

[0149] in, represents the fifth PI controller, k p5 and k i5 denote the proportional parameter and integral parameter of the fifth PI controller respectively;

[0150] The command value i of the q-axis current inner loop qrefk and the feedback value of q-axis current i qk After the error passes through the sixth PI controller, the q-axis modulation voltage u is obtained. qk ;

[0151] ;

[0152] in, represents the sixth PI controller, k p6 and k i6 denote the proportional parameter and integral parameter of the sixth PI controller respectively;

[0153] Modulation voltage u dk and u qk After the inverse rotation coordinate transformation, the three-phase AC modulation voltage u is obtained abck ; Then the on and off of the flywheel side rectifier switching device is controlled to realize the charging and discharging of the flywheel motor according to the power of the demagnetization coil.

[0154] like Figure 5 As shown in Figure 1, the bidirectional DC / DC converter maintains the DC bus voltage constant by:

[0155] Adopting the control mode of DC voltage outer loop and current inner loop;

[0156] The voltage outer loop control mode is: demagnetization power supply DC bus voltage command value U dcref and 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 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.

[0157] ;

[0158] in, represents the seventh PI controller, k p7 and k i7 represent the proportional parameter and integral parameter of the seventh PI controller respectively;

[0159] The current inner loop control mode is: the current inner loop command value i dcrefk and the bidirectional DC / DC converter output current i 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.

[0160]

[0161] in, represents the eighth PI controller, k p8 and ki8 They represent the proportional parameter and integral parameter of the eighth PI controller respectively.

[0162] Application Examples

[0163] 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. The transformer ratio is 10kV / 0.69kV. The grid-side rectifier adopts bridge PWM rectification. Its topology is shown in the figure. 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 is shown in Figure 8 A total of five 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 to the DC side of the grid-side rectifier through a bidirectional DC / DC converter. The topology of the bidirectional DC / DC converter is shown in Figure 9 The flywheel side rectifier outputs a DC voltage of 1200V. Its topology is shown in Figure 10 .

[0164] 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 on for 1s and the current pulse is off for 3s; the negative pulse current amplitude is 4300A, the current pulse is on for 5s and the current pulse is off for 7s. The simulated current waveform of the degaussing coil is as follows: Figure 11 As shown in the figure, the simulation current accuracy is about 0.17%, which meets the requirements of the demagnetization working condition. The output power simulation waveform of the flywheel energy storage device is as follows: Figure 12 As shown in Figure 1, during the degaussing coil pulse current off period, the flywheel energy storage device absorbs power from the grid side to store energy, and during the degaussing coil current pulse on period, the flywheel energy storage device provides power to the coil. The power simulation waveform on the grid side is shown in Figure 1. Figure 13 As shown in the figure, it can be seen that during the process of turning on and off 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 increase and decrease of the degaussing coil is smoothed by the flywheel energy storage device. Figure 14 As shown in the figure, the DC bus voltage fluctuates around 2500V, with little overall change.

[0165] In summary, the flywheel energy storage degaussing power supply proposed in the present invention can meet the power supply demand of the degaussing 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 degaussing operation.

[0166] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0167] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A demagnetization main power supply system based on flywheel energy storage, characterized in that: Includes medium and high voltage feeder cabinets, transformers, grid-side rectifiers, four-quadrant DC / DC converters, flywheel energy storage units 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 units; All flywheel energy storage units are connected in parallel to the DC side of the grid-side rectifier; Each flywheel energy storage unit includes at least one flywheel motor, the same number of flywheel-side converters 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 unit, used to match the energy and power changes caused by sudden changes in the working state of the degaussing coil; 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 and the output current through 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 obtain the duty cycle of the four-quadrant DC / DC converter d ; Then the on and off of the four-quadrant DC / DC converter switching device is controlled to achieve current waveform control of the degaussing coil and limit the power of the degaussing coil.

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

3. The demagnetization main power supply system based on flywheel energy storage according to claim 1 is 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 demagnetization main power supply system based on flywheel energy storage according to claim 1 is characterized in that: The grid-side rectifier adopts constant power mode control, the specific method is: According to the power instruction of the grid-side rectifier, the instruction 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 into the feedback value of the d-axis and q-axis current after the rotation coordinate transformation. 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 , get the d-axis modulation voltage u d ; in, ω 0 is the fundamental angular frequency of the grid voltage, L is the filter inductance value; Command value of 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 The three-phase AC modulation voltage is obtained by reverse coordinate transformation u abc , and then controls the on and off of the grid-side rectifier switching devices to achieve constant power mode control.

5. The demagnetization main power supply system based on flywheel energy storage according to claim 1 is characterized in that: 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 DC voltage command value of the flywheel side converter U dcrefk and 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 is 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 The three-phase AC modulation voltage is obtained by reverse rotation coordinate transformation u abck ; Then the on and off of the flywheel side rectifier switching device is controlled to realize the charging and discharging of the flywheel motor according to the power of the demagnetization coil.

6. The demagnetization main power supply system based on flywheel energy storage according to claim 1, characterized in that: The bidirectional DC / DC converter maintains a constant DC bus voltage 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 and 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 and 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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