A distribution network and electric energy management equipment thereof

Abstract

The present application discloses an electric energy management device for a distribution network, including: a rectifier module whose input end receives the alternating current of the distribution network and whose output end is connected to the DC bus, used to rectify the received alternating current and compensate for the imbalance of the three-phase load of the distribution network; a first capacitor whose first end is connected to the positive bus in the DC bus and whose second end is connected to the negative bus in the DC bus; an inverter module whose input end is connected to the DC bus and whose output end is connected to the distribution network, used to reduce the harmonic amplitude of the distribution network. The solution of the present application has both the functions of three-phase imbalance compensation and harmonic management. The present application also provides a distribution network with corresponding technical effects.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power grid, and in particular to a distribution network and electric energy management equipment thereof. Background Art

[0002] In the distribution network, three-phase imbalance and harmonics will affect the power supply quality and reduce the stability of the power grid. Especially as more and more distributed devices and current electronic devices are connected to the distribution network, the research and development of new power management equipment has become particularly urgent.

[0003] Power management equipment usually needs to have high efficiency, high reliability, and fast dynamic response to ensure the stable and reliable operation of the distribution network. Traditional power management equipment usually only involves harmonic management, or only involves three-phase unbalanced compensation, or only involves reactive power compensation. The functions are seriously single and cannot meet the diversified needs of modern power systems.

[0004] In summary, how to more effectively manage the electric energy of the distribution network is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The object of the present invention is to provide a power distribution network and electric energy management equipment thereof, so as to more effectively manage the electric energy of the distribution network.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] An electric energy management device for a distribution network, comprising:

[0008] A rectifier module having an input end receiving alternating current from a distribution network and an output end connected to a DC bus, for rectifying the received alternating current and compensating for unbalanced three-phase loads of the distribution network;

[0009] A first capacitor having a first end connected to a positive busbar in the DC busbar and a second end connected to a negative busbar in the DC busbar;

[0010] An inverter module having an input end connected to the DC bus and an output end connected to the distribution network, and used for reducing the harmonic amplitude of the distribution network.

[0011] Preferably, it also includes:

[0012] A supercapacitor module having a first end connected to a positive bus in the DC bus and a second end connected to a negative bus in the DC bus, and being used to reduce a power variation amplitude of the DC bus when a power variation amplitude of the DC bus exceeds a predetermined range within a preset first time period.

[0013] Preferably, the rectifier module comprises:

[0014] An A-phase rectifier unit receiving an A-phase AC input from the distribution network, a B-phase rectifier unit receiving a B-phase AC input from the distribution network, and a C-phase rectifier unit receiving a C-phase AC input from the distribution network, wherein the A-phase rectifier unit, the B-phase rectifier unit, and the C-phase rectifier unit are all connected to the DC bus;

[0015] A first controller; used to control each switch tube in each phase rectifier unit based on the acquired data information of the distribution network using the first execution unit to compensate for the unbalanced three-phase load of the distribution network;

[0016] The first execution unit.

[0017] Preferably, the first controller is specifically used for:

[0018] pass Determine the mean current reference value I avr ;in, is the DC bus voltage target value, U dc is the DC bus voltage sampling value, K p is the preset proportional adjustment coefficient, K i is the preset integral adjustment coefficient, s is the complex frequency domain operator;

[0019] The current target value adjustment amount ΔI is determined by ΔI=(I2-I1) / 2, and the three-phase voltage U of the distribution network is determined. AN ,U BN ,U CN The maximum value, the second largest value and the minimum value are set, and the first current target value I ref1 =I avr +ΔI as the current target value of the rectifier unit corresponding to the maximum value, and the second current target value I ref2 =I avr As the current target value of the rectifier unit corresponding to the second largest value, the third current target value I ref3 =I avr -ΔI is used as the current target value of the rectifier unit corresponding to the minimum value;

[0020] Among them, U AN Corresponding to the A phase rectifier unit, U BN Corresponding to the B phase rectifier unit, U CN Corresponding to the C-phase rectifier unit; I2 represents the three-phase voltage U of the distribution network AN ,U BN ,U CN The maximum value of the phase current in this phase, I1 represents the three-phase voltage U of the distribution network AN ,U BN ,U CNThe minimum value of the phase current in this phase;

[0021] The first execution unit includes:

[0022] A first execution subunit is used to control each switch tube in the A-phase rectifier unit according to the current target value of the A-phase rectifier unit, so that the A-phase current reaches the current target value of the A-phase rectifier unit;

[0023] The second execution subunit is used to control each switch tube in the B-phase rectifier unit according to the current target value of the B-phase rectifier unit, so that the B-phase current reaches the current target value of the B-phase rectifier unit;

[0024] The third execution subunit is used to control each switch tube in the C-phase rectifier unit according to the current target value of the C-phase rectifier unit, so that the C-phase current reaches the current target value of the C-phase rectifier unit.

[0025] Preferably, the first controller is also used for:

[0026] After determining the mean current reference value I avr Afterwards, judge Is it greater than or equal to the preset ratio value?

[0027] If yes, the operation of determining the current target value adjustment amount ΔI by ΔI=(I2-I1) / 2 is performed;

[0028] If not, the current target value of the A-phase rectifier unit, the current target value of the B-phase rectifier unit, and the current target value of the C-phase rectifier unit are all set to the mean current reference value I avr ;

[0029] in, U AN ,U BN ,U CN Represents the A phase, B phase, and C phase voltages of the distribution network, ε AB Represents the voltage difference between phase A and phase B of the distribution network, ε AC Represents the voltage difference between phase A and phase C of the distribution network, ε BC Indicates the voltage difference between phase B and phase C of the distribution network.

[0030] Preferably, the inverter module comprises:

[0031] The first inverter unit, the second inverter unit, the third inverter unit, the fourth inverter unit, the fifth inverter unit, the sixth inverter unit, and the seventh inverter unit, and the input end of each inverter unit is connected to the DC bus, and the output end is connected to the distribution network,

[0032] A second controller, configured to control each switch in each inverter unit by using a second execution unit based on the acquired data information of the distribution network, so as to reduce the harmonic amplitude of the distribution network;

[0033] The second execution unit.

[0034] Preferably, the first inverter unit is an inverter unit for reducing the 5th harmonic of the distribution network, the second inverter unit is an inverter unit for reducing the 7th harmonic of the distribution network, the third inverter unit is an inverter unit for reducing the 11th harmonic of the distribution network, the fourth inverter unit is an inverter unit for reducing the 13th harmonic of the distribution network, the fifth inverter unit is an inverter unit for reducing the 17th harmonic of the distribution network, the sixth inverter unit is an inverter unit for reducing the 19th harmonic of the distribution network, and the seventh inverter unit is an inverter unit for reducing other high-order harmonics of the distribution network except the 5th, 7th, 11th, 13th, 17th and 19th harmonics.

[0035] Preferably, the second controller is specifically used for:

[0036] Based on the obtained three-phase voltage U of the distribution network AN ,U BN ,U CN And the three-phase current I AN ,I BN ,I CN , through the dq decomposition method, the fifth harmonic current value I in the three-phase current is extracted h5 , 7th harmonic current value I h7 , 11th harmonic current value I h11 , 13th harmonic current value I h13 , 17th harmonic current value I h17 , 19th harmonic current value I h19 , and other high-order harmonic current values ​​I except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics h , so that the second execution unit controls each switch tube in the corresponding inverter unit according to the 7 harmonic current values ​​to complete harmonic current compensation;

[0037] The DFFT method is used to calculate the three-phase current I AN ,I BN ,I CN Perform offline harmonic analysis to extract I h5 The corresponding harmonic residual value I h5e , I h7 The corresponding harmonic residual value I h7e , I h11 The corresponding harmonic residual value I h11e , Ih13 The corresponding harmonic residual value I h13e , I h17 The corresponding harmonic residual value I h17e , I h19 The corresponding harmonic residual value I h19e , I h The corresponding harmonic residual value I he ;

[0038] Will I h5 +k h5e *I h5e As the updated current reference value for the first inverter unit, I h7 +k h7e *I h7e As the updated current reference value for the second inverter unit, I h11 +k h11e *I h11e As the updated current reference value for the third inverter unit, I h13 +k h13e *I h13e As the updated current reference value for the fourth inverter unit, I h17 +k h17e *I h17e As the updated current reference value for the fifth inverter unit, I h19 +k h19e *I h19e As the updated current reference value for the sixth inverter unit, I h +k he *I he as the updated current reference value for the seventh inverter unit, so that the second execution unit controls each switch tube in the corresponding inverter unit according to the 7 updated current reference values ​​to complete harmonic current compensation;

[0039] Among them, k h5e , k h7e , k h11e , k h13e , k h17e , k h19e , k he are all harmonic compensation coefficients, and for any harmonic compensation coefficient, when the harmonic residual value corresponding to the harmonic compensation coefficient is divided by (I AN +I BN +I CN ) is greater than or equal to 0.001, the harmonic compensation coefficient is 1, otherwise it is 0.

[0040] Preferably, it also includes:

[0041] A first soft switch unit disposed between the DC bus and the first inverter unit;

[0042] A second soft switch unit disposed between the DC bus and the second inverter unit;

[0043] A third soft switch unit disposed between the DC bus and the third inverter unit;

[0044] A fourth soft switch unit disposed between the DC bus and the fourth inverter unit;

[0045] A fifth soft switch unit disposed between the DC bus and the fifth inverter unit;

[0046] A sixth soft switch unit disposed between the DC bus and the sixth inverter unit;

[0047] A seventh soft switch unit provided between the DC bus and the seventh inverter unit;

[0048] For any soft switch unit, the soft switch unit includes:

[0049] A target capacitor having a first end connected to a positive bus in the DC bus and a second end connected to a first end of a target inductor;

[0050] A first target switch tube having a first end connected to a positive bus in the DC bus and a second end respectively connected to a first end of a second target switch tube and a positive input end of a corresponding inverter unit;

[0051] the second target switch tube having a second end connected to the second end of the target inductor;

[0052] the target inductance;

[0053] Among them, for any soft switching unit, when the switching state of any switch tube in the inverter unit corresponding to the soft switching unit is flipped, the first target switch tube in the soft switching unit is turned on and the second target switch tube is turned off, and lasts for a first time period, and after lasting for the first time period, it is restored to the default state in which the first target switch tube in the soft switching unit is turned off and the second target switch tube is turned on, and the first time period is equal to the dead time of the same bridge arm switch tube of the inverter unit corresponding to the soft switching unit.

[0054] A distribution network, comprising the electric energy management equipment of the distribution network as described in any one of the above items.

[0055] Applying the technical solution provided by the embodiment of the present invention, considering that the functions of traditional power management equipment are seriously single and cannot meet the diversified needs of modern power systems, this application adopts power management equipment with both three-phase imbalance compensation and harmonic management functions. Specifically, this application can compensate for the three-phase imbalance of the distribution network through a rectifier module, and at the same time, it can reduce the harmonics of the distribution network through an inverter module. The first capacitor set on the DC bus serves as the energy transmission hub of the power management equipment of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 It is a structural schematic diagram of an electric energy management device for a distribution network in the present invention;

[0058] Figure 2 It is a structural schematic diagram of an electric energy management device of a distribution network in a specific implementation mode of the present invention;

[0059] Figure 3 A schematic diagram of the control structure of a first controller and a first execution unit in an electric energy management device of a distribution network in a specific implementation manner of the present invention;

[0060] Figure 4 It is a schematic diagram of the structure of the electric energy management equipment of the distribution network in another specific implementation manner of the present invention. DETAILED DESCRIPTION

[0061] The core of the present invention is to provide an electric energy management device for a distribution network, which has both three-phase unbalance compensation and harmonic control functions.

[0062] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0063] Please refer to Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of an electric energy management device for a distribution network, and the electric energy management device for the distribution network may include:

[0064] A rectifier module 10 having an input end receiving AC power from a distribution network and an output end connected to a DC bus, for rectifying the received AC power and compensating for unbalanced three-phase loads of the distribution network;

[0065] A first capacitor C0 having a first end connected to a positive busbar in the DC busbar and a second end connected to a negative busbar in the DC busbar;

[0066] The input end is connected to the DC bus, and the output end is connected to the power distribution network, and the inverter module 20 is used to reduce the harmonic amplitude of the power distribution network.

[0067] Specifically, the present application compensates for the three-phase imbalance of the distribution network through the rectifier module 10. The specific structure of the rectifier module 10 and the corresponding method of compensating for the three-phase load imbalance of the distribution network can be set and selected according to actual needs as long as they can meet the purpose of the present application.

[0068] In a specific implementation of the present invention, the rectifier module 10 is composed of an A-phase rectifier unit 11 , a B-phase rectifier unit 12 , a C-phase rectifier unit 13 , a first controller and a first execution unit, and has a good implementation effect.

[0069] In this specific embodiment of the present invention, the rectifier module 10 includes:

[0070] An A-phase rectifier unit 11 receiving an A-phase AC input from a distribution network, a B-phase rectifier unit 12 receiving a B-phase AC input from a distribution network, and a C-phase rectifier unit 13 receiving a C-phase AC input from a distribution network, and the A-phase rectifier unit 11, the B-phase rectifier unit 12, and the C-phase rectifier unit 13 are all connected to a DC bus;

[0071] A first controller; used to control each switch tube in each phase rectifier unit based on the acquired data information of the distribution network using the first execution unit to compensate for the unbalanced three-phase load of the distribution network;

[0072] The first execution unit.

[0073] In this embodiment, the A-phase rectifier unit 11, the B-phase rectifier unit 12 and the C-phase rectifier unit 13 are usually single-phase bridge-type fully-controlled rectifier units, and the components therein are usually 4 controllable switch tubes. Figure 2 In the implementation manner, each phase rectifier unit is a single-phase bridge fully controlled rectifier unit, and the components therein are 4 controllable switch tubes, for example, they can be MOS tubes, IGBTs and other switch tubes. In addition, Figure 2 In the embodiment of the present invention, the first controller and the first execution unit are not shown.

[0074] Specifically, for the rectifier unit of any phase, the first end of the first switch tube of the phase rectifier unit is connected to the first end of the second switch tube and serves as the first output end of the phase rectifier unit, the second end of the first switch tube of the phase rectifier unit is connected to the first end of the fourth switch tube and serves as the first input end of the phase rectifier unit, the second end of the second switch tube of the phase rectifier unit is connected to the first end of the third switch tube and serves as the second input end of the phase rectifier unit, and the second end of the third switch tube of the phase rectifier unit is connected to the second end of the fourth switch tube and serves as the second output end of the phase rectifier unit.

[0075] The first input end of the A-phase rectifier unit 11 is connected to the A-phase of the distribution network, the second input end of the A-phase rectifier unit 11 is connected to the N-line of the distribution network, that is, the neutral end, the first output end of the A-phase rectifier unit 11 is connected to the positive bus in the DC bus, and the second output end of the A-phase rectifier unit 11 is connected to the negative bus in the DC bus. Correspondingly, the first input end of the B-phase rectifier unit 12 is connected to the B-phase of the distribution network, the second input end of the B-phase rectifier unit 12 is connected to the N-line of the distribution network, the first output end of the B-phase rectifier unit 12 is connected to the positive bus in the DC bus, and the second output end of the B-phase rectifier unit 12 is connected to the negative bus in the DC bus. The first input end of the C-phase rectifier unit 13 is connected to the C-phase of the distribution network, the second input end of the C-phase rectifier unit 13 is connected to the N-line of the distribution network, the first output end of the C-phase rectifier unit 13 is connected to the positive bus in the DC bus, and the second output end of the C-phase rectifier unit 13 is connected to the negative bus in the DC bus.

[0076] The first controller can respectively determine the current target values ​​for the A-phase rectifier unit 11, the B-phase rectifier unit 12 and the C-phase rectifier unit 13, and then the first execution unit can control each switch tube in each phase rectifier unit according to the current target value of the corresponding rectifier unit to achieve compensation for the unbalanced three-phase load of the distribution network.

[0077] In a specific embodiment of the present invention, the first controller is specifically used for:

[0078] pass Determine the mean current reference value I avr ;in, is the DC bus voltage target value, U dc is the DC bus voltage sampling value, K p is the preset proportional adjustment coefficient, K i is the preset integral adjustment coefficient, s is the complex frequency domain operator;

[0079] The current target value adjustment amount ΔI is determined by ΔI=(I2-I1) / 2, and the three-phase voltage U of the distribution network is determined. AN ,U BN ,U CNThe maximum value, the second largest value and the minimum value are set, and the first current target value I ref1 =I avr +ΔI as the current target value of the rectifier unit corresponding to the maximum value, and the second current target value I ref2 =I avr As the current target value of the rectifier unit corresponding to the second largest value, the third current target value I ref3 =I avr -ΔI is used as the current target value of the rectifier unit corresponding to the minimum value;

[0080] Among them, U AN Corresponding to A phase rectifier unit 11, U BN Corresponding to B phase rectifier unit 12, U CN Corresponding to the C-phase rectifier unit 13; I2 represents the three-phase voltage U of the distribution network AN ,U BN ,U CN The maximum value of the phase current in this phase, I1 represents the three-phase voltage U of the distribution network AN ,U BN ,U CN The minimum value of the phase current in this phase;

[0081] The first execution unit includes:

[0082] The first execution subunit 151 is used to control each switch tube in the A-phase rectifier unit 11 according to the current target value of the A-phase rectifier unit 11, so that the A-phase current reaches the current target value of the A-phase rectifier unit 11;

[0083] The second execution subunit 152 is used to control each switch tube in the B-phase rectifier unit 12 according to the current target value of the B-phase rectifier unit 12, so that the B-phase current reaches the current target value of the B-phase rectifier unit 12;

[0084] The third execution subunit 153 is used to control each switch tube in the C-phase rectifying unit 13 according to the current target value of the C-phase rectifying unit 13 so that the C-phase current reaches the current target value of the C-phase rectifying unit 13 .

[0085] In this embodiment, the first controller 14 first needs to Determine the mean current reference value I avr This process can be completed based on PID feedback, see Figure 3 That is, As the target quantity of PID, U dc Can approach Determine the mean current reference value I avr Afterwards, the first controller 14 needs to determine the current target value of each phase rectifier unit.

[0086] For example, at a certain moment, the distribution network U AN >U BN >U CN , then ΔI=(I2-I1) / 2=(I AN -I CN ) / 2, at this time, the first current target value I ref1 =I avr +ΔI as U AN The current target value of the corresponding rectifier unit is used as the current target value of the A-phase rectifier unit 11. ref2 =I avr As the current target value of the B-phase rectifier unit 12, the third current target value I ref3 =I avr −ΔI is used as the current target value of the C-phase rectifying unit 13 .

[0087] It is understandable that when the U AN >U BN >U CN , indicating that the load of phase A is lighter and the load of phase C is heavier. In order to compensate for the three-phase imbalance, the current target value of the phase A rectifier unit 11 is increased, that is, the first current target value I ref1 =I avr +ΔI is used as the current target value of the A-phase rectifying unit 11, thereby increasing the load of the A-phase. Accordingly, the current target value of the C-phase rectifying unit 13 is reduced, thereby reducing the load of the C-phase.

[0088] For example, at a certain moment, the U BN >U AN >U CN , then ΔI=(I2-I1) / 2=(I BN -I CN ) / 2, at this time, the first current target value I ref1 =I avr +ΔI as U BN The current target value of the corresponding rectifier unit is used as the current target value of the B-phase rectifier unit 12. ref2 =I avr As the current target value of the A-phase rectifier unit 11, the third current target value I ref3 =I avr −ΔI is used as the current target value of the C-phase rectifying unit 13 .

[0089] After the first controller 14 determines the current target values ​​of the A-phase, B-phase and C-phase rectifier units, the first execution unit can control each switch tube in each phase rectifier unit based on the determined current target values ​​of the A-phase, B-phase and C-phase rectifier units to compensate for the three-phase imbalance of the distribution network.

[0090] Specifically, in this implementation, the first execution unit is composed of a first execution sub-unit 151 , a second execution sub-unit 152 and a third execution sub-unit 153 .

[0091] Taking the first execution subunit 151 as an example, the second execution subunit 152 and the third execution subunit 153 are similar. The first execution subunit 151 can control each switch tube in the A-phase rectifier unit 11 according to the current target value of the A-phase rectifier unit 11, so that the A-phase current reaches the current target value of the A-phase rectifier unit 11. For details, please refer to Figure 3 The first execution subunit 151 can be composed of a first current regulator and a first PWM modulator, according to the current target value of the A-phase rectifier unit 11, combined with the d-axis component v of the A-phase voltage dA , q-axis component v qA , the d-axis component i of the A-phase current dA , q-axis component i qA The first current regulator can output a corresponding control signal to the first PWM modulator, and the first PWM modulator can output a corresponding PWM control signal accordingly, thereby controlling each switch tube in the A-phase rectifier unit 11, for example, applied to Figure 2 In the implementation method, it is to control Figure 2 The switch tubes S11, S12, S13 and S14 are turned on so that the A-phase current reaches the current target value of the A-phase rectifier unit 11.

[0092] In this specific implementation manner, the first controller 14 determines the mean current reference value I avr When the DC bus voltage is fed back, feedback control is performed on the DC bus voltage, that is, the rectifier module 10 in this embodiment is a structure of a voltage outer loop plus a current inner loop, which can compensate for the unbalanced load of the three-phase distribution network and also realize the control of the DC bus voltage.

[0093] Furthermore, in a specific implementation of the present invention, when the degree of three-phase imbalance in the distribution network is low, compensation may not be required, which is conducive to reducing the consumption of computing resources and avoiding meaningless control by the first controller. In this implementation, the first controller may also be used for:

[0094] After determining the mean current reference value I avr Afterwards, judge Is it greater than or equal to the preset ratio value?

[0095] If yes, the operation of determining the current target value adjustment amount ΔI by ΔI=(I2-I1) / 2 is performed;

[0096] If not, the current target value of the A-phase rectifier unit 11, the current target value of the B-phase rectifier unit 12, and the current target value of the C-phase rectifier unit 13 are all set to the mean current reference value I avr ;

[0097] in, U AN ,U BN ,U CN Represents the A phase, B phase, and C phase voltages of the distribution network, ε AB Represents the voltage difference between phase A and phase B of the distribution network, ε AC Represents the voltage difference between phase A and phase C of the distribution network, ε BC Indicates the voltage difference between phase B and phase C of the distribution network.

[0098] The specific value of the preset ratio can be set and adjusted according to actual needs. For example, it is set to 3%, that is, Is it true? If so, it means that the three-phase imbalance of the distribution network is more serious. Therefore, the current target value of each phase rectifier unit can be calculated as in the above embodiment. If not, it means that the three-phase imbalance is less. In order to avoid meaningless calculation and control, in this embodiment, the current target value of the three-phase rectifier unit can be directly set to the mean current reference value I avr .

[0099] The first capacitor C0 is arranged in the middle DC link, that is, between the positive bus and the negative bus, and can usually be selected as an electrolytic capacitor. The first capacitor C0 is the energy transmission hub link of the power management equipment of the entire distribution network.

[0100] The inverter module 20 is arranged between the DC bus and the power distribution network, and can reduce the harmonic amplitude of the power distribution network.

[0101] The inverter module 20 may have various specific structures as long as the purpose of reducing the harmonics of the power distribution network can be achieved.

[0102] In a specific embodiment of the present invention, considering that the conventional inverter module 20 is composed of a single inverter, the effect of reducing harmonics is not good. Therefore, in this embodiment, the inverter module 20 includes:

[0103] The first inverter unit 21, the second inverter unit 22, the third inverter unit 23, the fourth inverter unit 24, the fifth inverter unit 25, the sixth inverter unit 26, and the seventh inverter unit 27, and the input end of each inverter unit is connected to the DC bus, and the output end is connected to the distribution network,

[0104] A second controller is used to control each switch tube in each inverter unit based on the acquired data information of the distribution network by using the second execution unit to reduce the harmonics of the distribution network;

[0105] The second execution unit.

[0106] In this implementation, seven parallel inverter units are used to reduce the harmonics of the distribution network, which is beneficial to improving the effect of reducing harmonics. Figure 2 In the specific implementation manner, 7 parallel three-phase bridge arm inverter units are shown. In addition, Figure 2 The second controller and the second execution unit are not shown.

[0107] Furthermore, the present application takes into account that the 5th, 7th, 11th, 13th, 17th, and 19th harmonics are relatively common and have larger amplitudes. Therefore, in a specific embodiment of the present invention, the first inverter unit 21 is an inverter unit for reducing the 5th harmonic of the distribution network, the second inverter unit 22 is an inverter unit for reducing the 7th harmonic of the distribution network, the third inverter unit 23 is an inverter unit for reducing the 11th harmonic of the distribution network, the fourth inverter unit 24 is an inverter unit for reducing the 13th harmonic of the distribution network, the fifth inverter unit 25 is an inverter unit for reducing the 17th harmonic of the distribution network, the sixth inverter unit 26 is an inverter unit for reducing the 19th harmonic of the distribution network, and the seventh inverter unit 27 is an inverter unit for reducing other high-order harmonics of the distribution network except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics.

[0108] In a specific embodiment of the present invention, the second controller is specifically used for:

[0109] Based on the obtained three-phase voltage U of the distribution network AN ,U BN ,U CN And the three-phase current I AN ,I BN ,I CN , through the dq decomposition method, the fifth harmonic current value I in the three-phase current is extracted h5 , 7th harmonic current value I h7 , 11th harmonic current value I h11 , 13th harmonic current value I h13 , 17th harmonic current value I h17 , 19th harmonic current value Ih19 , and other high-order harmonic current values ​​I except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics h , so that the second execution unit controls the switches in the corresponding inverter units according to the seven harmonic current values ​​to complete harmonic current compensation;

[0110] The DFFT method is used to calculate the three-phase current I AN ,I BN ,I CN Perform offline harmonic analysis to extract I h5 The corresponding harmonic residual value I h5e , I h7 The corresponding harmonic residual value I h7e , I h11 The corresponding harmonic residual value I h11e , I h13 The corresponding harmonic residual value I h13e , I h17 The corresponding harmonic residual value I h17e , I h19 The corresponding harmonic residual value I h19e , I h The corresponding harmonic residual value I he ;

[0111] Will I h5 +k h5e *I h5e As the updated current reference value for the first inverter unit 21, I h7 +k h7e *I h7e As the updated current reference value for the second inverter unit 22, I h11 +k h11e *I h11e As the updated current reference value for the third inverter unit 23, I h13 +k h13e *I h13e As the updated current reference value for the fourth inverter unit 24, I h17 +k h17e *I h17e As the updated current reference value for the fifth inverter unit 25, I h19 +k h19e *I h19e As the updated current reference value for the sixth inverter unit 26, I h +k he *I heas the updated current reference value for the seventh inverter unit 27, so that the second execution unit controls each switch tube in the corresponding inverter unit according to the 7 updated current reference values ​​to complete harmonic current compensation;

[0112] Among them, k h5e , k h7e , k h11e , k h13e , k h17e , k h19e , k he are all harmonic compensation coefficients, and for any harmonic compensation coefficient, when the harmonic residual value corresponding to the harmonic compensation coefficient is divided by (I AN +I BN +I CN ) is greater than or equal to 0.001, the harmonic compensation coefficient is 1, otherwise it is 0.

[0113] In this embodiment, the second controller extracts the fifth harmonic current value I in the three-phase current of the distribution network. h5 , 7th harmonic current value I h7 , 11th harmonic current value I h11 , 13th harmonic current value I h13 , 17th harmonic current value I h17 , 19th harmonic current value I h19 , and other high-order harmonic current values ​​I except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics h Afterwards, the second execution unit can control each switch in the corresponding inverter unit based on the 7 harmonic current values ​​to compensate for the harmonic current. The second execution unit can be composed of 7 current regulators and 7 PWM modulators, each current regulator is connected to a corresponding PWM modulator and is responsible for controlling the corresponding inverter unit.

[0114] It is understandable that based on I h5 , I h7 , I h11 , I h13 , I h17 , I h19 and I h After harmonic compensation, the harmonic content in the three-phase current of the distribution network can be reduced. In this implementation, in order to further reduce the harmonics, the DFFT method is also used to calculate the three-phase current I AN ,I BN ,I CN Perform offline harmonic analysis to extract the uncompensated harmonic residual value, that is, extract I h5 The corresponding harmonic residual value I h5e , Ih7 The corresponding harmonic residual value I h7e , I h11 The corresponding harmonic residual value I h11e , I h13 The corresponding harmonic residual value I h13e , I h17 The corresponding harmonic residual value I h17e , I h19 The corresponding harmonic residual value I h19e , I h The corresponding harmonic residual value I he ;

[0115] In calculating the harmonic compensation coefficient k h5e , k h7e , k h11e , k h13e , k h17e , k h19e , k he When the value of Is it true, for example, Then k h5e The value is 1. For example, If it does not hold, then k h7e The value is 0. That is, only when the harmonic residual value reaches a certain amplitude, the harmonic residual value will affect the value of the current reference value.

[0116] After obtaining the seven updated current reference values, the second execution unit can control each switch tube in the corresponding inverter unit based on the seven current reference values ​​to achieve more accurate harmonic current compensation.

[0117] In a specific embodiment of the present invention, please refer to Figure 4 , and may also include:

[0118] The first end is connected to the positive bus in the DC bus, and the second end is connected to the negative bus in the DC bus. The supercapacitor module 30 is used to reduce the power variation amplitude of the DC bus when the power variation amplitude of the DC bus exceeds a predetermined range within a preset first time period.

[0119] The specific structure and corresponding working process of the supercapacitor module 30 can be various, for example, Figure 2 In the embodiment, a supercapacitor module 30 composed of a supercapacitor Cx, an inductor L, a switch tube S1, and a switch tube S2 is shown. Of course, the relevant control structure in the supercapacitor module 30 is Figure 4 Not shown in FIG.

[0120] Since the supercapacitor module 30 is provided, the power fluctuation at the first capacitor C0 can be reduced, that is, the short-term large power fluctuation of the power management equipment of the distribution network can be suppressed, thereby improving the balance and reliability of power transmission.

[0121] Furthermore, in a specific embodiment of the present invention, it may also include:

[0122] A first soft switch unit 41 is arranged between the DC bus and the first inverter unit 21;

[0123] A second soft switch unit 42 disposed between the DC bus and the second inverter unit 22;

[0124] A third soft switch unit 43 disposed between the DC bus and the third inverter unit 23;

[0125] A fourth soft switch unit 44 is provided between the DC bus and the fourth inverter unit 24;

[0126] A fifth soft switch unit 45 disposed between the DC bus and the fifth inverter unit 25;

[0127] A sixth soft switch unit 46 disposed between the DC bus and the sixth inverter unit 26;

[0128] The seventh soft switching unit 47 is arranged between the DC bus and the seventh inverter unit 27 .

[0129] By setting the soft switch unit, the power conversion efficiency of the inverter unit can be improved. The specific structure of each soft switch unit can also be set and adjusted according to actual needs. For example, in a specific embodiment of the present invention, for any soft switch unit, the soft switch unit includes:

[0130] A target capacitor having a first end connected to a positive bus in a DC bus and a second end connected to a first end of a target inductor;

[0131] A first target switch tube having a first end connected to a positive bus in a DC bus and a second end respectively connected to a first end of a second target switch tube and a positive input end of a corresponding inverter unit;

[0132] a second target switch tube having a second end connected to a second end of the target inductor;

[0133] Target inductance;

[0134] Among them, for any soft switching unit, when the switching state of any switch tube in the inverter unit corresponding to the soft switching unit is flipped, the first target switch tube in the soft switching unit is turned on and the second target switch tube is turned off, and lasts for a first time period, and after lasting for the first time period, it is restored to the default state in which the first target switch tube in the soft switching unit is turned off and the second target switch tube is turned on, and the first time period is equal to the dead time of the same bridge arm switch tube of the inverter unit corresponding to the soft switching unit.

[0135] Figure 2 In the embodiment of the present invention, the structure of the soft switch unit in the embodiment is shown. Figure 2 For example, when [V 11 V 12 V 13 V 14 V 15 V 16 V 17 V 18 ] when the control signal of any switch tube in the soft switch circuit V 19 On, V 1X The duration is Td, where Td represents the dead time of the same bridge arm switch of the first inverter unit 21. 19 On / off, V 1X Conductivity. Figure 2 The principles of the second to seventh soft switching units in are consistent with this. By ensuring the freewheeling during the dead time, the power conversion efficiency of the inverter unit can be improved.

[0136] In the scheme of the present application, considering that the functions of traditional power management equipment are seriously single and cannot meet the diversified needs of modern power systems, the present application adopts power management equipment with both three-phase imbalance compensation and harmonic management functions. Specifically, the present application can compensate for the three-phase imbalance of the distribution network through the rectifier module 10, and at the same time, the harmonics of the distribution network can be reduced through the inverter module 20. In addition, the first capacitor C0 arranged on the DC bus is the energy transmission hub of the power management equipment of the distribution network.

[0137] In addition, the present application provides a supercapacitor module 30, through which the power fluctuation at the first capacitor C0 can be reduced, that is, the probability mutation of the first capacitor C0 can be smoothed, which is beneficial to ensuring the stable operation of the power management equipment of the distribution network, and is also beneficial to further improve the stability of the distribution network.

[0138] Corresponding to the above embodiments of the power management equipment for the distribution network, an embodiment of the present invention further provides a distribution network, including the power management equipment for the distribution network as in any of the above embodiments, which can be referenced in correspondence with the above and will not be repeated here.

[0139] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, the elements defined by the statement "including a ..." do not exclude the presence of other identical elements in the process, article or device including the elements.

[0140] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0141] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, the present invention can also be improved and modified without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An electric energy management device for a distribution network, characterized in that: include: A rectifier module having an input end receiving alternating current from a distribution network and an output end connected to a DC bus, for rectifying the received alternating current and compensating for unbalanced three-phase loads of the distribution network; A first capacitor having a first end connected to a positive busbar in the DC busbar and a second end connected to a negative busbar in the DC busbar; An inverter module having an input end connected to the DC bus and an output end connected to the distribution network, and used to reduce the harmonic amplitude of the distribution network; The rectifier module comprises: An A-phase rectifier unit receiving an A-phase AC input from the distribution network, a B-phase rectifier unit receiving a B-phase AC input from the distribution network, and a C-phase rectifier unit receiving a C-phase AC input from the distribution network, wherein the A-phase rectifier unit, the B-phase rectifier unit, and the C-phase rectifier unit are all connected to the DC bus; A first controller; used to control each switch tube in each phase rectifier unit based on the acquired data information of the distribution network using the first execution unit to compensate for the unbalanced three-phase load of the distribution network; the first execution unit; The first controller is specifically used for: pass Determine the mean current reference value I avr ;in, is the DC bus voltage target value, U dc is the DC bus voltage sampling value, K p is the preset proportional adjustment coefficient, K i is the preset integral adjustment coefficient, s is the complex frequency domain operator; The current target value adjustment amount △I is determined by △I=(I2-I1) / 2, where U AN Corresponding to the A phase rectifier unit, U BN Corresponding to the B phase rectifier unit, U CN Corresponding to the C-phase rectifier unit; I2 represents the three-phase voltage U of the distribution network AN ,U BN ,U CN The maximum value of the phase current in this phase, I1 represents the three-phase voltage U of the distribution network AN ,U BN ,U CN The minimum value of the phase current in this phase; According to the three-phase voltage U AN ,U BN ,U CN Determine the three-phase voltage U of the distribution network AN ,U BN ,U CN The maximum, second largest, and minimum values ​​in ; The first current target value I ref1 =I avr +△I as the current target value of the rectifier unit corresponding to the maximum value, and the second current target value I ref2 =I avr As the current target value of the rectifier unit corresponding to the second largest value, the third current target value I ref3 =I avr -△I is used as the current target value of the rectifier unit corresponding to the minimum value.

2. The power management device for the distribution network according to claim 1, characterized in that: Also includes: A supercapacitor module having a first end connected to a positive bus in the DC bus and a second end connected to a negative bus in the DC bus, and being used to reduce a power variation amplitude of the DC bus when a power variation amplitude of the DC bus exceeds a predetermined range within a preset first time period.

3. The electric energy management equipment for the distribution network according to claim 1, characterized in that: The first execution unit includes: A first execution subunit is used to control each switch tube in the A-phase rectifier unit according to the current target value of the A-phase rectifier unit, so that the A-phase current reaches the current target value of the A-phase rectifier unit; The second execution subunit is used to control each switch tube in the B-phase rectifier unit according to the current target value of the B-phase rectifier unit, so that the B-phase current reaches the current target value of the B-phase rectifier unit; The third execution subunit is used to control each switch tube in the C-phase rectifier unit according to the current target value of the C-phase rectifier unit, so that the C-phase current reaches the current target value of the C-phase rectifier unit.

4. The electric energy management equipment for the distribution network according to claim 1, characterized in that: The first controller is also used for: After determining the mean current reference value I avr Afterwards, judge Is it greater than or equal to the preset ratio value? If yes, the operation of determining the current target value adjustment amount ΔI by ΔI=(I2-I1) / 2 is performed; If not, the current target value of the A-phase rectifier unit, the current target value of the B-phase rectifier unit, and the current target value of the C-phase rectifier unit are all set to the mean current reference value I avr ; in, U AN ,U BN ,U CN Represents the A phase, B phase, and C phase voltages of the distribution network, ε AB Represents the voltage difference between phase A and phase B of the distribution network, ε AC Represents the voltage difference between phase A and phase C of the distribution network, ε BC Indicates the voltage difference between phase B and phase C of the distribution network.

5. The electric energy management equipment for the distribution network according to claim 1, characterized in that: The inverter module comprises: The first inverter unit, the second inverter unit, the third inverter unit, the fourth inverter unit, the fifth inverter unit, the sixth inverter unit, and the seventh inverter unit, and the input end of each inverter unit is connected to the DC bus, and the output end is connected to the distribution network, A second controller, configured to control each switch in each inverter unit by using a second execution unit based on the acquired data information of the distribution network, so as to reduce the harmonic amplitude of the distribution network; The second execution unit.

6. The electric energy management equipment for the distribution network according to claim 5, characterized in that: The first inverter unit is an inverter unit for reducing the 5th harmonic of the distribution network, the second inverter unit is an inverter unit for reducing the 7th harmonic of the distribution network, the third inverter unit is an inverter unit for reducing the 11th harmonic of the distribution network, the fourth inverter unit is an inverter unit for reducing the 13th harmonic of the distribution network, the fifth inverter unit is an inverter unit for reducing the 17th harmonic of the distribution network, the sixth inverter unit is an inverter unit for reducing the 19th harmonic of the distribution network, and the seventh inverter unit is an inverter unit for reducing other high-order harmonics of the distribution network except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics.

7. The electric energy management equipment for the distribution network according to claim 6, characterized in that: The second controller is specifically used for: Based on the obtained three-phase voltage U of the distribution network AN ,U BN ,U CN And the three-phase current I AN ,I BN ,I CN , through the dq decomposition method, the fifth harmonic current value I in the three-phase current is extracted h5 , 7th harmonic current value I h7 , 11th harmonic current value I h11 , 13th harmonic current value I h13 , 17th harmonic current value I h17 , 19th harmonic current value I h19 , and other high-order harmonic current values ​​I except the 5th, 7th, 11th, 13th, 17th, and 19th harmonics h , so that the second execution unit controls each switch tube in the corresponding inverter unit according to the 7 harmonic current values ​​to complete harmonic current compensation; The DFFT method is used to calculate the three-phase current I AN ,I BN ,I CN Perform offline harmonic analysis to extract I h5 The corresponding harmonic residual value I h5e , I h7 The corresponding harmonic residual value I h7e , I h11 The corresponding harmonic residual value I h11e , I h13 The corresponding harmonic residual value I h13e , I h17 The corresponding harmonic residual value I h17e , I h19 The corresponding harmonic residual value I h19e , I h The corresponding harmonic residual value I he ; Will I h5 +k h5e *I h5e As the updated current reference value for the first inverter unit, I h7 +k h7e *I h7e As the updated current reference value for the second inverter unit, I h11 +k h11e *I h11e As the updated current reference value for the third inverter unit, I h13 +k h13e *I h13e As the updated current reference value for the fourth inverter unit, I h17 +k h17e *I h17e As the updated current reference value for the fifth inverter unit, I h19 +k h19e *I h19e As the updated current reference value for the sixth inverter unit, I h +k he *I he as the updated current reference value for the seventh inverter unit, so that the second execution unit controls each switch tube in the corresponding inverter unit according to the 7 updated current reference values ​​to complete harmonic current compensation; Among them, k h5e , k h7e , k h11e , k h13e , k h17e , k h19e , k he are all harmonic compensation coefficients, and for any harmonic compensation coefficient, when the harmonic residual value corresponding to the harmonic compensation coefficient is divided by (I AN +I BN +I CN ) is greater than or equal to 0.001, the harmonic compensation coefficient is 1, otherwise it is 0.

8. The electric energy management equipment for the distribution network according to claim 5, characterized in that: Also includes: A first soft switch unit disposed between the DC bus and the first inverter unit; A second soft switch unit disposed between the DC bus and the second inverter unit; A third soft switch unit disposed between the DC bus and the third inverter unit; A fourth soft switch unit disposed between the DC bus and the fourth inverter unit; A fifth soft switch unit disposed between the DC bus and the fifth inverter unit; A sixth soft switch unit disposed between the DC bus and the sixth inverter unit; A seventh soft switch unit provided between the DC bus and the seventh inverter unit; For any soft switch unit, the soft switch unit includes: A target capacitor having a first end connected to a positive bus in the DC bus and a second end connected to a first end of a target inductor; A first target switch tube having a first end connected to a positive bus in the DC bus and a second end respectively connected to a first end of a second target switch tube and a positive input end of a corresponding inverter unit; the second target switch tube having a second end connected to the second end of the target inductor; the target inductance; Among them, for any soft switching unit, when the switching state of any switch tube in the inverter unit corresponding to the soft switching unit is flipped, the first target switch tube in the soft switching unit is turned on and the second target switch tube is turned off, and lasts for a first time period, and after lasting for the first time period, it is restored to the default state in which the first target switch tube in the soft switching unit is turned off and the second target switch tube is turned on, and the first time period is equal to the dead time of the same bridge arm switch tube of the inverter unit corresponding to the soft switching unit.

9. A distribution network, characterized in that: An electric energy management device for a distribution network comprising the equipment described in any one of claims 1 to 8.

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