Reconstructed microgrid power adaptive control method and device based on mobile power supply vehicle

Abstract

The present invention discloses a power adaptive control method for a reconstructed microgrid based on a mobile power supply vehicle, comprising: collecting DC side voltage, AC side voltage and AC side current to calculate a droop deviation; calculating an adaptive droop gain according to the droop deviation and its derivative; correcting the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation; inputting the corrected droop deviation into a PID controller to obtain a power reference parameter; performing conversion and power calculation according to the AC side voltage and the AC side current to obtain a power calculation parameter; calculating a power control parameter according to the power reference parameter and the power calculation parameter, and generating a control signal for the DC / AC converter according to the power control parameter; the method enables the reconstructed microgrid to obtain optimal system power sharing coordination when responding to various disturbances.

Description

Technical Field

[0001] The present invention relates to the technical field of microgrids, and in particular to a method and device for adaptively controlling power of a reconstructed microgrid based on a mobile power supply vehicle. Background Art

[0002] With the rapid development of renewable energy and distributed power generation technology, microgrids, as a new type of power system, are receiving more and more attention. Microgrids are composed of multiple distributed power sources, energy storage devices and loads, and have the advantages of flexibility, reliability and efficiency. However, the operation of microgrids faces many challenges, such as the intermittent and uncertain nature of renewable energy, load changes, equipment failures, etc. Mobile power supply vehicles, as a new type of energy storage device, have the advantages of flexibility, mobility and rapid response. For example, patent text CN117097008A provides a low-voltage power supply vehicle paralleling and grid-connected system and its control method. Introducing mobile power supply vehicles into microgrids can effectively improve the power supply capacity and reliability of microgrids.

[0003] However, the introduction of mobile power vehicles also brings new challenges to the operation of microgrids. For example, the location, capacity, and power output of the mobile power vehicles all need to be optimized and controlled. The DC / AC converter serves as a bridge for power transmission between the AC and DC sides of the reconstructed microgrid after the power vehicle is deployed, and plays an important role in inter-grid power coordination and mutual support. Some literature uses the droop characteristics of AC and DC subgrids, using the normalized values ​​of AC frequency and DC voltage as criteria for judging the power surplus state of the subgrid, to achieve load balancing and power sharing in AC / DC hybrid microgrids. However, under complex actual operating conditions, power coordination between the AC and DC sides is affected by factors such as the rated capacity and inertia differences of the parallel subgrids and DC / AC converters. DC / AC converter control strategies based on fixed droop coefficients have power transfer deviations, making it difficult to fully achieve coordinated optimization of overall power sharing. Summary of the Invention

[0004] The present invention provides a method and device for adaptively controlling power of a reconstructed microgrid based on a mobile power supply vehicle, which enables an AC / DC hybrid microgrid to achieve optimal system power sharing coordination when responding to various disturbances.

[0005] A power adaptive control method for a reconfigured microgrid based on a mobile power supply vehicle, wherein the reconfigured microgrid includes an AC side, a DC side, a DC / AC converter, and a mobile power supply vehicle, wherein the AC side and the DC side are connected via a DC / AC converter, and the mobile power supply vehicle is connected to the AC side; the method comprises:

[0006] Collect DC side voltage, AC side voltage and AC side current, and calculate droop deviation;

[0007] Calculating an adaptive droop gain according to the droop deviation and its derivative;

[0008] Correcting the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation;

[0009] Inputting the corrected droop deviation into a PID controller to obtain a power reference parameter;

[0010] Performing conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters;

[0011] A power control parameter is calculated based on the power reference parameter and the power calculation parameter, and a control signal for the DC / AC converter is generated based on the power control parameter.

[0012] Furthermore, the calculating of the droop deviation includes:

[0013] Calculating the AC bus frequency according to the AC side voltage and the AC side current;

[0014] Normalizing the AC bus frequency and the DC side voltage to obtain a normalized AC bus frequency and a normalized DC side voltage;

[0015] The difference between the normalized AC bus frequency and the normalized DC side voltage is used as the droop deviation.

[0016] Furthermore, the adaptive droop gain is calculated according to the following formula:

[0017]

[0018] Where K represents the adaptive droop gain, K max represents the maximum value of the adaptive droop gain, K0 represents the initial value of the adaptive droop gain, K min Represents the minimum value of the adaptive droop gain, e pu represents the droop deviation, α and β are adjustable parameters, and ε is the minimum value greater than 0.

[0019] Furthermore, the corrected droop deviation is calculated using the following formula:

[0020]

[0021] Among them, e' pu Indicates the correction of droop deviation, K indicates the adaptive droop gain, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

[0022] Furthermore, the DC side includes a DC subnet, the AC side includes an AC subnet, and the DC subnet and the AC subnet autonomously share power based on a droop equation;

[0023] The method further comprises:

[0024] Determine the subnet to be compensated according to the inertia strength of the DC subnet and the AC subnet;

[0025] Setting an inertial dynamic compensator in the subnet to be compensated;

[0026] Calculating the inertia compensation power of the subnet to be compensated based on the inertia dynamic compensator;

[0027] Introducing the inertia compensation power into the droop equation of the subnet to be compensated to obtain the inertia compensation droop equation;

[0028] The subgrid to be compensated autonomously shares power based on the inertia compensation droop equation.

[0029] Furthermore, the inertia compensation power is calculated by the following formula:

[0030]

[0031] Among them, P g Indicates the inertia compensation power, P g,0 Indicates the initial value of inertia supplementary power, K g Indicates the inertia compensation gain, x n,pu Indicates the normalized DC side voltage or AC bus frequency of the subnet to be compensated, S n It represents the rated capacity of the subnet to be supplemented, and γ is an adjustable parameter.

[0032] Furthermore, the inertia compensation droop equation is as follows:

[0033]

[0034] Among them, f ac Indicates the AC bus frequency, V dc Indicates the DC side voltage, f acn Indicates the rated value of the current frequency on the AC side, V dcn Indicates the rated value of DC side voltage, P gac Indicates the inertia compensation power when the subnet to be compensated is an AC subnet, P gdc represents the inertia compensation power when the subnet to be supplemented is a DC subnet, P'0 represents the initial power of the droop control of the subnet to be supplemented, m ac Indicates the Pf droop coefficient, m dc is the droop coefficient on the DC side, P' acIndicates the active power output when the subnet to be compensated is an AC subnet, P' dc Indicates the actual output power when the subnet to be compensated is a DC subnet.

[0035] Furthermore, the method further comprises:

[0036] Calculate the change in AC bus frequency and DC side voltage within a preset time period;

[0037] When the change in the AC bus frequency and the change in the DC side voltage are less than a first preset value, setting the transmission power of the DC / AC converter to 0;

[0038] When the change in the AC bus frequency is greater than a second preset value and / or the change in the DC side voltage is greater than a third preset value, the transmission power of the DC / AC converter is set to a maximum transmission power.

[0039] Furthermore, performing conversion and power calculation according to the AC side voltage and the AC side current to obtain power calculation parameters includes:

[0040] Calculating the AC side active power and the AC side reactive power according to the AC side voltage and the AC side current;

[0041] Get the initial power on the AC side;

[0042] Performing dq transformation on the AC side voltage and the AC side current to obtain a d-axis voltage, a q-axis voltage, a d-axis current, and a q-axis current;

[0043] A power current loop calculation is performed based on the AC side active power, AC side reactive power, AC side initial power, d-axis voltage, q-axis voltage, d-axis current and q-axis current to obtain a reference voltage for the SVPWM link.

[0044] A power adaptive control device for reconfigured microgrid based on a mobile power supply vehicle applied to the above method comprises:

[0045] The acquisition module is used to collect DC side voltage, AC side voltage and AC side current, and calculate the droop deviation;

[0046] An adaptive calculation module, configured to calculate an adaptive droop gain according to the droop deviation and its derivative;

[0047] a correction module, configured to correct the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation;

[0048] A PID control module, configured to input the corrected droop deviation into a PID controller to obtain a power reference parameter;

[0049] A power calculation module, configured to perform conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters;

[0050] A control module is configured to calculate a power control parameter based on the power reference parameter and the power calculation parameter, and generate a control signal for the DC / AC converter based on the power control parameter.

[0051] Furthermore, the acquisition module calculates the droop deviation, including:

[0052] Calculating the AC bus frequency according to the AC side voltage and the AC side current;

[0053] Normalizing the AC bus frequency and the DC side voltage to obtain a normalized AC bus frequency and a normalized DC side voltage;

[0054] The difference between the normalized AC bus frequency and the normalized DC side voltage is used as the droop deviation.

[0055] Furthermore, the adaptive droop gain is calculated according to the following formula:

[0056]

[0057] Where K represents the adaptive droop gain, K max represents the maximum value of the adaptive droop gain, K0 represents the initial value of the adaptive droop gain, K min Represents the minimum value of the adaptive droop gain, e pu represents the droop deviation, α and β are adjustable parameters, and ε is the minimum value greater than 0.

[0058] Furthermore, the corrected droop deviation is calculated using the following formula:

[0059]

[0060] Among them, e' pu Indicates the correction of droop deviation, K indicates the adaptive droop gain, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

[0061] Furthermore, the DC side includes a DC subnet, the AC side includes an AC subnet, and the DC subnet and the AC subnet autonomously share power based on a droop equation;

[0062] The device further comprises a compensation module, configured to:

[0063] Determine the subnet to be compensated according to the inertia strength of the DC subnet and the AC subnet;

[0064] Setting an inertial dynamic compensator in the subnet to be compensated;

[0065] Calculating the inertia compensation power of the subnet to be compensated based on the inertia dynamic compensator;

[0066] Introducing the inertia compensation power into the droop equation of the subnet to be compensated to obtain the inertia compensation droop equation;

[0067] The subgrid to be compensated autonomously shares power based on the inertia compensation droop equation.

[0068] Furthermore, the inertia compensation power is calculated by the following formula:

[0069]

[0070] Among them, P g Indicates the inertia compensation power, P g,0 Indicates the initial value of inertia supplementary power, K g Indicates the inertia compensation gain, x n,pu Indicates the normalized DC side voltage or AC bus frequency of the subnet to be compensated, S n It represents the rated capacity of the subnet to be supplemented, and γ is an adjustable parameter.

[0071] Furthermore, the inertia compensation droop equation is as follows:

[0072]

[0073] Among them, f ac Indicates the AC bus frequency, V dc Indicates the DC side voltage, f acn Indicates the rated value of the current frequency on the AC side, V dcn Indicates the rated value of DC side voltage, P gac Indicates the inertia compensation power when the subnet to be compensated is an AC subnet, P gdc represents the inertia compensation power when the subnet to be supplemented is a DC subnet, P'0 represents the initial power of the droop control of the subnet to be supplemented, m ac Indicates the Pf droop coefficient, m dc is the droop coefficient on the DC side, P' ac Indicates the active power output when the subnet to be compensated is an AC subnet, P' dc Indicates the actual output power when the subnet to be compensated is a DC subnet.

[0074] Furthermore, the device further includes a limiting module, configured to:

[0075] Calculate the change in AC bus frequency and DC side voltage within a preset time period;

[0076] When the change in the AC bus frequency and the change in the DC side voltage are less than a first preset value, setting the transmission power of the DC / AC converter to 0;

[0077] When the change in the AC bus frequency is greater than a second preset value and / or the change in the DC side voltage is greater than a third preset value, the transmission power of the DC / AC converter is set to a maximum transmission power.

[0078] Furthermore, the power calculation module performs conversion and power calculation according to the AC side voltage and the AC side current to obtain power calculation parameters, including:

[0079] Calculating the AC side active power and the AC side reactive power according to the AC side voltage and the AC side current;

[0080] Get the initial power on the AC side;

[0081] Performing dq transformation on the AC side voltage and the AC side current to obtain a d-axis voltage, a q-axis voltage, a d-axis current, and a q-axis current;

[0082] A power current loop calculation is performed based on the AC side active power, AC side reactive power, AC side initial power, d-axis voltage, q-axis voltage, d-axis current and q-axis current to obtain a reference voltage for the SVPWM link.

[0083] The method and device for adaptively controlling power of a reconstructed microgrid based on a mobile power supply vehicle provided by the present invention have at least the following beneficial effects:

[0084] (1) The droop deviation in the control process is adjusted based on the adaptive droop gain, so that the AC / DC hybrid reconfigured microgrid can achieve the best system power sharing coordination when dealing with various disturbances;

[0085] (2) Adding limiting and hysteresis control to the droop control of the DC / AC converter can not only limit the instantaneous power fluctuation from exceeding the threshold, but also avoid the repeated switching of the power flow direction of the DC / AC converter, and improve the stability and reliability of the system power transmission.

[0086] (3) In the DC / AC converter, a dynamic inertia compensator is added to optimize the dynamic response of frequency / voltage, reduce the inertia difference between the AC side and the DC side, and its impact on the system power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 The present invention provides a flowchart of an embodiment of a method for adaptively controlling power of a reconstructed microgrid based on a mobile power supply vehicle.

[0088] Figure 2This is a structural schematic diagram of an embodiment of reconstructing a microgrid in the power adaptive control method for reconstructing a microgrid based on a mobile power supply vehicle provided by the present invention.

[0089] Figure 3 The present invention provides a flowchart of an embodiment of the present invention for calculating the droop deviation of the power adaptive control method for reconstructing the microgrid based on the mobile power vehicle.

[0090] Figure 4 This is a schematic diagram of an embodiment of the adaptive droop coefficient gain characteristic in the power adaptive control method for reconstructing a microgrid based on a mobile power vehicle provided by the present invention.

[0091] Figure 5 This is a schematic diagram of an embodiment of power calculation in the power adaptive control method for reconstructing a microgrid based on a mobile power vehicle provided by the present invention.

[0092] Figure 6 Flowchart of an embodiment of power calculation in the power adaptive control method for reconstructing microgrid based on mobile power vehicle provided by the present invention

[0093] Figure 7 A structural diagram of another embodiment of the microgrid reconstruction method based on the mobile power vehicle provided by the present invention

[0094] Figure 8 The present invention provides a flowchart of an embodiment of inertia compensation in a power adaptive control method for reconstructing a microgrid based on a mobile power vehicle.

[0095] Figure 9 The present invention provides a flowchart of an embodiment of AC subgrid droop control in a power adaptive control method for reconstructing a microgrid based on a mobile power vehicle.

[0096] Figure 10 The present invention provides a flowchart of an embodiment of the DC subgrid droop control method in the power adaptive control method of the reconstructed microgrid based on the mobile power vehicle.

[0097] Figure 11 This is a flow chart of an embodiment of the power adaptive control device for reconstructing a microgrid based on a mobile power vehicle provided by the present invention. DETAILED DESCRIPTION

[0098] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0099] refer to Figure 1 and Figure 2In some embodiments, a method for adaptive power control of a reconstructed microgrid based on a mobile power supply vehicle is provided. The reconstructed microgrid includes an AC side 1, a DC side 2, a DC / AC converter 3, and a mobile power supply vehicle 4. The AC side 1 and the DC side 2 are connected via the DC / AC converter 3, and the mobile power supply vehicle 4 is connected to the AC side 1. The method includes:

[0100] S1, collect DC side voltage, AC side voltage and AC side current, and calculate droop deviation;

[0101] S2. Calculating an adaptive droop gain based on the droop deviation and its derivative;

[0102] S3. Correcting the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation;

[0103] S4. Inputting the corrected droop deviation into a PID controller to obtain a power reference parameter;

[0104] S5. Performing conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters;

[0105] S6. Calculate a power control parameter according to the power reference parameter and the power calculation parameter, and generate a control signal for the DC / AC converter according to the power control parameter.

[0106] The DC / AC converter is used to control power transmission between the DC side and the AC side according to the control signal.

[0107] Specifically, refer to Figure 3 In step S1, the calculation of the droop deviation includes:

[0108] S11. Calculating the AC bus frequency according to the AC side voltage and the AC side current;

[0109] S12, normalizing the AC bus frequency and the DC side voltage to obtain a normalized AC bus frequency and a normalized DC side voltage;

[0110] S13. Taking the difference between the normalized AC bus frequency and the normalized DC side voltage as the droop deviation.

[0111] Furthermore, in step S11, the AC side voltage is the AC bus voltage, and the DC side current is the DC bus voltage.

[0112] Furthermore, in step S12, the normalized feature quantity calculation formula is:

[0113]

[0114] Where x is the AC bus frequency or DC side voltage, x max and x min are the maximum and minimum values ​​of the AC bus frequency or DC side voltage, respectively, Δx max is the maximum deviation of AC bus frequency or DC side voltage; x pu It can be a normalized characteristic quantity of AC frequency or DC voltage, that is, the normalized AC bus frequency or the normalized DC side voltage.

[0115] Furthermore, in step S13, the droop deviation is calculated using the following formula:

[0116] e pu =f ac,pu -V dc,pu ; (2)

[0117] Among them, e pu Indicates the droop deviation, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

[0118] Droop deviation e pu The size reflects the power balance on both sides.

[0119] Furthermore, in step S2, the adaptive droop gain is calculated according to the following formula:

[0120]

[0121] Where K represents the adaptive droop gain, K max represents the maximum value of the adaptive droop gain, K0 represents the initial value of the adaptive droop gain, K min Represents the minimum value of the adaptive droop gain, e pu represents the droop deviation, α and β are adjustable parameters, and ε is the minimum value greater than 0, which can be 0.005.

[0122] The designed adaptive droop coefficient gain characteristic is as follows Figure 4 shown.

[0123] Furthermore, in step S3, the corrected droop deviation is calculated using the following formula:

[0124]

[0125] Among them, e' pu Indicates the correction of droop deviation, K indicates the adaptive droop gain, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

[0126] By introducing the variable K, the normalized droop deviation e is corrected pu Adaptively adjust the support strength of the DC and AC sides to cope with the impact of various disturbances on power dispatch.

[0127] Further, refer to Figure 5 In step S4, the modified droop deviation is input into the PID controller to obtain a power reference parameter, which is the transmission power reference value P of the DC / AC converter. ref , the reference value calculation formula of the transmission power of the DC / AC converter 3 is:

[0128]

[0129] Among them, P ref k is the transmission power reference value of the DC / AC converter; p,ILC 、k i,ILC 、k d,ICL They are the proportional coefficient, integral coefficient and differential coefficient of PID parameters respectively, where k p,ILC Can be set as the droop coefficient of the DC / AC converter. PID control is used to track the droop deviation e pu , and reduce the steady-state difference between voltage deviation and frequency deviation.

[0130] Further, refer to Figure 5 and Figure 6 In step S5, the conversion and power calculation are performed according to the AC side voltage and the AC side current to obtain power calculation parameters, including:

[0131] S51, calculating the AC side active power P according to the AC side voltage and AC side current ilc and AC side reactive power Q ilc ;

[0132] S52, obtaining the initial power P0 on the AC side;

[0133] S53, performing dq transformation on the AC side voltage and AC side current to obtain the d-axis voltage V d , q-axis voltage V q , d-axis current i d and q-axis current i q ;

[0134] S54, according to the AC side active power P ilc , AC side reactive power Q ilc , AC side initial power P0, d-axis voltage V d , q-axis voltage V q , d-axis current i d and q-axis current i qPerform power current loop calculation to obtain the reference voltage V of the SVPWM link abc，ref .

[0135] Furthermore, in step S6, a power control parameter is calculated based on the power reference parameter and the power calculation parameter, and a control signal for the DC / AC converter is generated based on the power control parameter.

[0136] Further, refer to Figure 7 The DC side 2 includes a DC bus and at least one DC subgrid 21, which is connected to the DC bus. The AC side 1 includes an AC bus and at least one AC subgrid 11, which is connected to the mobile power vehicle. The DC subgrid 21 and the AC subgrid 11 autonomously share power based on the droop equation.

[0137] Specifically, the AC subgrid and DC subgrid autonomously share power based on the frequency and voltage droop equations:

[0138]

[0139] Among them, P ac and Q ac are the active power and reactive power output of the AC subnet respectively, P acn and Q acn are the rated values ​​of active power and reactive power of AC subnet respectively, f acn and V acn are the rated values ​​of the frequency and voltage of the AC subnet, f' ac and V ac are the frequency and voltage values ​​output by the AC subnet, m ac and n ac are Pf and QV droop coefficients respectively. dc and P dcn are the actual value and rated value of the DC subnet output power, V dc and V dcn are the actual value and rated value of DC side voltage respectively, m dc is the droop coefficient on the DC side.

[0140] The droop factor depends on its rated power and the permissible voltage frequency and amplitude fluctuation range:

[0141]

[0142] Among them, P ac,max , Q ac,max 、P ac,min , and Q ac,min are the maximum active power, maximum reactive power, maximum active power and minimum reactive power output of the reconstructed microgrid, respectively.ac,max 、V ac,max 、f ac,min , and V ac,min are the maximum value of AC bus frequency fluctuation, the maximum value of output voltage fluctuation, the minimum value of AC bus frequency fluctuation and the minimum value of output voltage fluctuation on the AC side of the reconstructed microgrid respectively; P dc,max and P dc,min are the maximum and minimum output power of the DC side, V dc,max and V dc,min are the maximum and minimum values ​​of the DC voltage fluctuation range respectively.

[0143] To reduce the impact of inertia differences between the AC and DC subgrids on the dynamic power transmission process of the DC / AC converter, in some embodiments, a subgrid inertia compensator is designed. By designing a dynamic inertia compensator in the subgrid with weaker inertia, the difference in frequency and voltage response speed can be reduced. The dynamic inertia compensator introduces a frequency / voltage difference to buffer sudden frequency / voltage changes caused by power fluctuations. Taking the AC subgrid as an example, the faster the frequency changes, the greater the power of the dynamic inertia compensator to slow the rate of frequency change. When the frequency is about to reach a stable state, the power of the dynamic inertia compensator will decrease, but this will not affect the stable state of the frequency. The same is true for the DC subgrid.

[0144] Therefore, reference Figure 8 In some embodiments, the method further comprises:

[0145] S7. Determine the subnet to be compensated based on the inertia strengths of the DC subnet and the AC subnet;

[0146] S8. Setting an inertial dynamic compensator in the subnet to be compensated;

[0147] S9. Calculating the inertia compensation power of the subnet to be compensated based on the inertia dynamic compensator;

[0148] S10, introducing the inertia compensation power into the droop equation of the subnet to be compensated to obtain an inertia compensation droop equation;

[0149] S11. The subnet to be compensated autonomously shares power based on the inertia compensation droop equation.

[0150] Specifically, in step S7, the inertia strength of the corresponding DC subnet and AC subnet is determined based on the magnitude of the rate of change of the fluctuation of the DC bus voltage of the DC subnet and the AC bus frequency of the AC subnet as the disturbance occurs. If the rate of change of the fluctuation of the DC bus voltage of the DC subnet is greater than a fourth preset value, the corresponding DC subnet is determined to be the subnet to be compensated. If the rate of change of the fluctuation of the AC bus frequency of the AC subnet is greater than a fifth preset value, the corresponding AC subnet is determined to be the subnet to be compensated.

[0151] Furthermore, the inertia compensation power is calculated by the following formula:

[0152]

[0153] Among them, P g Indicates the inertia compensation power, P g,0 Indicates the initial value of inertia supplementary power, K g Indicates the inertia compensation gain, x n,pu Indicates the normalized DC side voltage or AC bus frequency of the subnet to be compensated, S n It represents the rated capacity of the subnet to be supplemented, and γ is an adjustable parameter.

[0154] The larger the inertia compensation gain is, the stronger the compensation effect is. If it is too large, it will cause system delay, so it can be set to 0.1-0.5.

[0155] Further, refer to Figure 9 and Figure 10 , AC subnet frequency control in droop control is as follows Figure 9 As shown, the DC subnet voltage control is as follows Figure 10 As shown, the inertia compensation droop equation is as follows:

[0156]

[0157] Among them, f ac Indicates the AC bus frequency, V dc Indicates the DC side voltage, f acn Indicates the rated value of the current frequency on the AC side, V dcn Indicates the rated value of DC side voltage, P gac Indicates the inertia compensation power when the subnet to be compensated is an AC subnet, P gdc represents the inertia compensation power when the subnet to be supplemented is a DC subnet, P'0 represents the initial power of the droop control of the subnet to be supplemented, m ac Indicates the Pf droop coefficient, m dc is the droop coefficient on the DC side, P' ac Indicates the active power output when the subnet to be compensated is an AC subnet, P' dc Indicates the actual output power when the subnet to be compensated is a DC subnet.

[0158] Furthermore, in order to prevent instantaneous power fluctuations from affecting the stability of system operation, a limiting and hysteresis control link is designed in the power transmission control link of the DC / AC converter. Therefore, the method further includes:

[0159] Calculate the change in AC bus frequency and DC side voltage within a preset time period;

[0160] When the change in the AC bus frequency and the change in the DC side voltage are less than a first preset value, setting the transmission power of the DC / AC converter to 0;

[0161] When the change in the AC bus frequency is greater than a second preset value and / or the change in the DC side voltage is greater than a third preset value, the transmission power of the DC / AC converter is set to a maximum transmission power.

[0162] The first preset value is a minimum value close to 0.

[0163] refer to Figure 11 In some embodiments, a power adaptive control device for reconfigured microgrid based on a mobile power supply vehicle is provided for use in the above method, comprising:

[0164] The acquisition module 201 is used to collect the DC side voltage, AC side voltage and AC side current, and calculate the droop deviation;

[0165] An adaptive calculation module 202 is configured to calculate an adaptive droop gain based on the droop deviation and its derivative;

[0166] a correction module 203, configured to correct the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation;

[0167] A PID control module 204 is configured to input the corrected droop deviation into a PID controller to obtain a power reference parameter;

[0168] A power calculation module 205 is configured to perform conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters;

[0169] The control module 206 is configured to calculate a power control parameter according to the power reference parameter and the power calculation parameter, and generate a control signal for the DC / AC converter according to the power control parameter.

[0170] Furthermore, the acquisition module 201 calculates the droop deviation, including:

[0171] Calculating the AC bus frequency according to the AC side voltage and the AC side current;

[0172] Normalizing the AC bus frequency and the DC side voltage to obtain a normalized AC bus frequency and a normalized DC side voltage;

[0173] The difference between the normalized AC bus frequency and the normalized DC side voltage is used as the droop deviation.

[0174] Furthermore, the adaptive droop gain is calculated according to the following formula:

[0175]

[0176] Where K represents the adaptive droop gain, K max represents the maximum value of the adaptive droop gain, K0 represents the initial value of the adaptive droop gain, K min Represents the minimum value of the adaptive droop gain, e pu represents the droop deviation, α and β are adjustable parameters, and ε is the minimum value greater than 0.

[0177] Furthermore, the corrected droop deviation is calculated using the following formula:

[0178]

[0179] Among them, e' pu Indicates the correction of droop deviation, K indicates the adaptive droop gain, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

[0180] Furthermore, the DC side includes a DC subnet, the AC side includes an AC subnet, and the DC subnet and the AC subnet autonomously share power based on a droop equation;

[0181] The device further comprises a compensation module, configured to:

[0182] Determine the subnet to be compensated according to the inertia strength of the DC subnet and the AC subnet;

[0183] Setting an inertial dynamic compensator in the subnet to be compensated;

[0184] Calculating the inertia compensation power of the subnet to be compensated based on the inertia dynamic compensator;

[0185] Introducing the inertia compensation power into the droop equation of the subnet to be compensated to obtain the inertia compensation droop equation;

[0186] The subgrid to be compensated autonomously shares power based on the inertia compensation droop equation.

[0187] Furthermore, the inertia compensation power is calculated by the following formula:

[0188]

[0189] Among them, P g Indicates the inertia compensation power, P g,0 Indicates the initial value of inertia supplementary power, K g Indicates the inertia compensation gain, x n,puIndicates the normalized DC side voltage or AC bus frequency of the subnet to be compensated, S n It represents the rated capacity of the subnet to be supplemented, and γ is an adjustable parameter.

[0190] Furthermore, the inertia compensation droop equation is as follows:

[0191]

[0192] Among them, f ac Indicates the AC bus frequency, V dc Indicates the DC side voltage, f acn Indicates the rated value of the current frequency on the AC side, V dcn Indicates the rated value of DC side voltage, P gac Indicates the inertia compensation power when the subnet to be compensated is an AC subnet, P gdc represents the inertia compensation power when the subnet to be supplemented is a DC subnet, P'0 represents the initial power of the droop control of the subnet to be supplemented, m ac Indicates the Pf droop coefficient, m dc is the droop coefficient on the DC side, P' ac Indicates the active power output when the subnet to be compensated is an AC subnet, P' dc Indicates the actual output power when the subnet to be compensated is a DC subnet.

[0193] Furthermore, the device further includes a limiting module, configured to:

[0194] Calculate the change in AC bus frequency and DC side voltage within a preset time period;

[0195] When the change in the AC bus frequency and the change in the DC side voltage are less than a first preset value, setting the transmission power of the DC / AC converter to 0;

[0196] When the change in the AC bus frequency is greater than a second preset value and / or the change in the DC side voltage is greater than a third preset value, the transmission power of the DC / AC converter is set to a maximum transmission power.

[0197] Furthermore, the power calculation module 205 performs transformation and power calculation according to the AC side voltage and the AC side current to obtain power calculation parameters, including:

[0198] Calculating the AC side active power and the AC side reactive power according to the AC side voltage and the AC side current;

[0199] Get the initial power on the AC side;

[0200] Performing dq transformation on the AC side voltage and the AC side current to obtain a d-axis voltage, a q-axis voltage, a d-axis current, and a q-axis current;

[0201] A power current loop calculation is performed based on the AC side active power, AC side reactive power, AC side initial power, d-axis voltage, q-axis voltage, d-axis current and q-axis current to obtain a reference voltage for the SVPWM link.

[0202] For the specific principles, please refer to the above method embodiment, which will not be repeated here.

[0203] The above embodiments provide a method and device for adaptively controlling power of a reconstructed microgrid based on a mobile power supply vehicle, which have at least the following beneficial effects:

[0204] (1) The droop deviation in the control process is adjusted based on the adaptive droop gain, so that the AC / DC hybrid reconfigured microgrid can achieve the best system power sharing coordination when dealing with various disturbances;

[0205] (2) Adding limiting and hysteresis control to the droop control of the DC / AC converter can not only limit the instantaneous power fluctuation from exceeding the threshold, but also avoid the repeated switching of the power flow direction of the DC / AC converter, and improve the stability and reliability of the system power transmission.

[0206] (3) In the DC / AC converter, a dynamic inertia compensator is added to optimize the dynamic response of frequency / voltage, reduce the inertia difference between the AC side and the DC side, and its impact on the system power transmission.

[0207] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and their equivalents.

Claims

1. A power adaptive control method for reconstructing a microgrid based on a mobile power vehicle, characterized in that: The reconstructed microgrid includes an AC side, a DC side, a DC / AC converter, and a mobile power supply vehicle, wherein the AC side and the DC side are connected via the DC / AC converter, and the mobile power supply vehicle is connected to the AC side; the method includes: Collect DC side voltage, AC side voltage and AC side current, and calculate droop deviation; Calculating an adaptive droop gain according to the droop deviation and its derivative; Correcting the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation; Inputting the corrected droop deviation into a PID controller to obtain a power reference parameter; Performing conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters; A power control parameter is calculated based on the power reference parameter and the power calculation parameter, and a control signal for the DC / AC converter is generated based on the power control parameter.

2. The method according to claim 1, characterized in that The calculation of the droop deviation includes: Calculating the AC bus frequency according to the AC side voltage and the AC side current; Normalizing the AC bus frequency and the DC side voltage to obtain a normalized AC bus frequency and a normalized DC side voltage; The difference between the normalized AC bus frequency and the normalized DC side voltage is used as the droop deviation.

3. The method according to claim 1, characterized in that The adaptive droop gain is calculated according to the following formula: Where K represents the adaptive droop gain, K max represents the maximum value of the adaptive droop gain, K0 represents the initial value of the adaptive droop gain, K min Represents the minimum value of the adaptive droop gain, e pu represents the droop deviation, α and β are adjustable parameters, and ε is the minimum value greater than 0.

4. The method according to claim 2, characterized in that The corrected droop deviation is calculated by the following formula: Among them, e' pu Indicates the correction of droop deviation, K indicates the adaptive droop gain, V dc,pu is the normalized DC side voltage, f ac,pu Represents the normalized AC bus frequency.

5. The method according to claim 1, characterized in that The DC side includes a DC subnet, the AC side includes an AC subnet, and the DC subnet and the AC subnet autonomously share power based on a droop equation; The method further comprises: Determine the subnet to be compensated according to the inertia strength of the DC subnet and the AC subnet; Setting an inertial dynamic compensator in the subnet to be compensated; Calculating the inertia compensation power of the subnet to be compensated based on the inertia dynamic compensator; Introducing the inertia compensation power into the droop equation of the subnet to be compensated to obtain the inertia compensation droop equation; The subgrid to be compensated autonomously shares power based on the inertia compensation droop equation.

6. The method according to claim 5, characterized in that The inertia compensation power is calculated by the following formula: Among them, P g Indicates the inertia compensation power, P g,0 Indicates the initial value of inertia supplementary power, K g Indicates the inertia compensation gain, x n,pu Indicates the normalized DC side voltage or AC bus frequency of the subnet to be compensated, S n It represents the rated capacity of the subnet to be supplemented, and γ is an adjustable parameter.

7. The method according to claim 5, characterized in that The inertia compensation droop equation is as follows: Among them, f ac Indicates the AC bus frequency, V dc Indicates the DC side voltage, f acn Indicates the rated value of the current frequency on the AC side, V dcn Indicates the rated value of DC side voltage, P gac Indicates the inertia compensation power when the subnet to be compensated is an AC subnet, P gdc represents the inertia compensation power when the subnet to be supplemented is a DC subnet, P'0 represents the initial power of the droop control of the subnet to be supplemented, m ac Indicates the Pf droop coefficient, m dc is the droop coefficient on the DC side, P' ac Indicates the active power output when the subnet to be compensated is an AC subnet, P' dc Indicates the actual output power when the subnet to be compensated is a DC subnet.

8. The method according to claim 1, characterized in that The method further comprises: Calculate the change in AC bus frequency and DC side voltage within a preset time period; When the change in the AC bus frequency and the change in the DC side voltage are less than a first preset value, setting the transmission power of the DC / AC converter to 0; When the change in the AC bus frequency is greater than a second preset value and / or the change in the DC side voltage is greater than a third preset value, the transmission power of the DC / AC converter is set to a maximum transmission power.

9. The method according to claim 1, characterized in that The converting and calculating power according to the AC side voltage and the AC side current to obtain power calculation parameters includes: Calculating the AC side active power and the AC side reactive power according to the AC side voltage and the AC side current; Get the initial power on the AC side; Performing dq transformation on the AC side voltage and the AC side current to obtain a d-axis voltage, a q-axis voltage, a d-axis current, and a q-axis current; A power current loop calculation is performed based on the AC side active power, AC side reactive power, AC side initial power, d-axis voltage, q-axis voltage, d-axis current and q-axis current to obtain a reference voltage for the SVPWM link.

10. A power adaptive control device for reconstructing a microgrid based on a mobile power supply vehicle applied to the method according to any one of claims 1 to 9, characterized in that: include: The acquisition module is used to collect DC side voltage, AC side voltage and AC side current, and calculate the droop deviation; An adaptive calculation module, configured to calculate an adaptive droop gain according to the droop deviation and its derivative; a correction module, configured to correct the droop deviation according to the adaptive droop gain to obtain a corrected droop deviation; A PID control module, configured to input the corrected droop deviation into a PID controller to obtain a power reference parameter; A power calculation module, configured to perform conversion and power calculation based on the AC side voltage and the AC side current to obtain power calculation parameters; A control module is configured to calculate a power control parameter based on the power reference parameter and the power calculation parameter, and generate a control signal for the DC / AC converter based on the power control parameter.

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