A ship-shore power grid connection control method and system

Abstract

The application provides a ship-shore power grid connection control method, comprising the following steps: sampling the output voltage of a shore power inverter device and the output voltage of a ship generator under load, and performing grid connection when the grid connection condition is met; after the grid connection, the output of the shore power inverter device is adjusted by using fuzzy internal model control based on droop control, and flexible grid connection between the ship and the shore is completed; the output of the shore power inverter device is adjusted by using fuzzy internal model control based on droop control, the controller parameter design is simplified, the control precision, the stability of the grid connection voltage and the frequency are improved, and the system robustness is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of ship-to-shore power systems, specifically relating to a ship-to-shore power grid connection control method and system. Background Technology

[0002] With the development of port cities and the call for energy conservation and emission reduction policies, the environmental pollution caused by ships docking at ports urgently needs to be addressed. Of the pollutants emitted from ports, 59% are inhalable particulate matter and 36% are NOx. X All power sources originate from ships docked in port. By using shore power systems, ships can shut down their auxiliary generators after docking and switch to shore power to meet their electricity needs, achieving zero emissions while the ship is in port. Flexible grid connection is the core technology of ship-to-shore power supply, enabling uninterrupted and stable power supply from shore to the ship. To successfully achieve flexible grid connection between ship and shore, on the one hand, the DC voltage on the rectifier side must be kept stable to ensure the normal operation of the frequency converter and the stability of the inverter output waveform under no-load or load conditions; on the other hand, when the shore power supply is connected to the main power grid and operated in parallel with the ship's generator, the grid connection impact must be controllable and the load transfer smooth. Currently, virtual synchronous generator control strategies and droop control strategies are widely used in ship-to-shore power grid connection systems.

[0003] Currently, the grid connection system of ships and shore power based on the traditional droop control strategy still has problems such as grid connection failure, grid voltage drop, frequency instability, and complex controller parameter design during actual operation. Therefore, how to solve the above-mentioned problems in the existing technology is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a ship-to-shore power grid connection control method, comprising:

[0005] The output voltage of the shore power inverter and the on-load output voltage of the ship generator are sampled, and grid connection is carried out after the grid connection conditions are met.

[0006] After grid connection, fuzzy internal model control based on droop control is used to adjust the output of the shore power inverter to complete the flexible grid connection between ship and shore.

[0007] Preferably, the output of the shore power inverter is adjusted using fuzzy internal model control based on droop control, including:

[0008] Based on the output voltage and current of the shore power inverter, the reference voltage and feedback voltage of the fuzzy voltage outer loop control are calculated.

[0009] Based on the reference voltage and feedback voltage of the outer loop control of the fuzzy voltage, the reference current of the inner loop control of the current is calculated.

[0010] Based on the capacitor current of the filter device on the back side of the inverter, calculate the feedback current of the inner loop inner mode control.

[0011] The reference current and feedback current of the inner current loop control are input into the inner current loop controller to obtain the input reference voltage of the shore power inverter.

[0012] Based on the input reference voltage of the shore power inverter, a modulation signal for the shore power inverter is generated;

[0013] The output of the shore power inverter is adjusted by the modulation signal of the shore power inverter.

[0014] Preferably, based on the output voltage and current of the shore power inverter, the reference voltage and feedback voltage for fuzzy voltage outer loop control are calculated, including:

[0015] The output voltage of the shore power inverter is input into the phase-locked loop to obtain the frequency and phase of the output voltage.

[0016] Calculate the corresponding active power and reactive power based on the output voltage and current of the shore power inverter.

[0017] The active power and reactive power are input into the droop characteristic equation to obtain the output frequency and voltage value of the shore power inverter.

[0018] Based on the output frequency and voltage value of the shore power inverter, the reference voltage for droop control is obtained;

[0019] Based on the frequency and phase of the output voltage, the droop control reference voltage is transformed into two-phase rotating dq coordinates to obtain the reference voltages of the d-axis and q-axis, which are used as the reference voltages for the fuzzy voltage outer loop control.

[0020] The output voltage of the shore power inverter is subjected to a two-phase rotating dq coordinate transformation to obtain the output voltages of the d-axis and q-axis, which are used as the feedback voltages for fuzzy voltage outer loop control.

[0021] Preferably, the droop characteristic equation is as follows:

[0022] ff _ref =-m(PP) _ref )

[0023] UU _ref =-n(QQ) _ref )

[0024] Among them, f _ref Here, f is the rated output frequency of the shore power inverter, m is the frequency droop coefficient, and P is the actual output active power of the shore power inverter. _refU is the output active power of the shore power inverter at rated frequency; U is the three-phase output voltage of the shore power inverter. _ref Let n be the rated three-phase output voltage of the shore power inverter, n be the voltage droop characteristic coefficient, and Q be the actual output reactive power of the shore power inverter. _ref This refers to the reactive power output of the shore power inverter at the rated frequency.

[0025] Preferably, based on the reference voltage and feedback voltage of the fuzzy voltage outer loop control, the reference current of the current inner loop inner model control is calculated, including:

[0026] Calculate voltage deviation based on reference voltage and feedback voltage;

[0027] Calculate the rate of change of deviation based on the voltage deviation;

[0028] The voltage deviation and the rate of change of deviation are fuzzified to obtain the membership degree of the fuzzy variable E corresponding to the voltage deviation and the membership degree of the fuzzy variable EC corresponding to the rate of change of deviation.

[0029] Based on the membership degrees of the fuzzy variable E and the fuzzy variable EC, a fuzzy decision is made to obtain the fuzzy value of the fuzzy output control parameter.

[0030] The fuzzy values ​​of the fuzzy output control parameters are defuzzified to obtain the exact values ​​of the fuzzy output control parameters.

[0031] The reference voltage is corrected based on the exact value of the fuzzy output control parameter.

[0032] The modified reference voltages are decoupled and summed to obtain the reference current for the inner loop inner mode control.

[0033] The preferred current inner loop inner model controller is as follows:

[0034]

[0035] Among them, G C (S) is the equivalent feedback loop controller obtained from the internal model controller, K PWM L1 is the voltage gain, L2 is the first filter inductor corresponding to the filter, C is the filter capacitor corresponding to the filter, a is the filter time constant of the internal mode control low-pass filter, and S is the differential operator.

[0036] Preferably, generating the modulation signal of the shore power inverter based on the input reference voltage of the shore power inverter includes:

[0037] The input reference voltage of the shore power inverter is transformed from a two-phase rotating dq coordinate system to a three-phase rotating abc coordinate system.

[0038] The input reference voltage of the shore power inverter in the three-phase rotating abc coordinate system is modulated with a triangular carrier wave to generate the modulation signal of the shore power inverter.

[0039] Preferably, the output voltage of the shore power inverter and the on-load output voltage of the ship generator are sampled, and grid connection is performed after the grid connection conditions are met, including:

[0040] Based on sampling of the output voltage of the shore power inverter and the on-load output voltage of the ship's generator, the shipside system sends voltage regulation commands to the shore power supply system.

[0041] The shore power supply system sends the voltage adjustment command to the shore power inverter to adjust the output voltage;

[0042] When the output voltage of the shore power inverter is consistent with the on-load output voltage of the ship's generator, it is connected to the grid.

[0043] Based on the same concept, the present invention also provides a ship-to-shore power grid connection control system, comprising:

[0044] The grid connection module is used to sample the output voltage of the shore power inverter and the on-load output voltage of the ship generator, and to connect to the grid after the grid connection conditions are met.

[0045] The adjustment module is used to adjust the output of the shore power inverter after grid connection by using fuzzy internal model control based on droop control, so as to complete the flexible grid connection between ship and shore.

[0046] Preferably, the adjustment module includes:

[0047] The fuzzy control input calculation module is used to calculate the reference voltage and feedback voltage for fuzzy voltage outer loop control based on the output voltage and current of the shore power inverter.

[0048] The inner model control input calculation module 1 is used to calculate the reference current of the inner model control of the current inner loop based on the reference voltage and feedback voltage of the outer loop control of the fuzzy voltage.

[0049] The inner model control input calculation module 1 is used to calculate the feedback current of the inner model control of the current inner loop based on the capacitor current of the filter device behind the inverter.

[0050] The inner model control module is used to input the reference current and feedback current of the inner current loop inner model control into the inner current loop inner model controller to obtain the input reference voltage of the shore power inverter.

[0051] The modulation signal module generates the modulation signal of the shore power inverter based on the input reference voltage of the shore power inverter.

[0052] The output adjustment module is used to adjust the output of the shore power inverter device by means of the modulation signal of the shore power inverter device.

[0053] Preferably, the fuzzy control input calculation module includes:

[0054] The phase-locked loop (PLL) calculation module is used to input the output voltage of the shore power inverter into the PLL to obtain the frequency and phase of the output voltage.

[0055] The power calculation module is used to calculate the corresponding active and reactive power based on the output voltage and current of the shore power inverter.

[0056] The droop control module 1 is used to input the active power and reactive power into the droop characteristic equation to obtain the output frequency and voltage value of the shore power inverter.

[0057] The droop control module 2 is used to obtain a reference voltage for droop control based on the output frequency and voltage value of the shore power inverter.

[0058] The reference voltage coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the droop control reference voltage based on the frequency and phase of the output voltage, so as to obtain the reference voltage of the d-axis and q-axis as the reference voltage for the fuzzy voltage outer loop control.

[0059] The coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the output voltage of the shore power inverter to obtain the output voltage of the d-axis and q-axis as the feedback voltage for fuzzy voltage outer loop control.

[0060] Preferably, the internal model control input calculation module 1 includes:

[0061] The voltage deviation calculation module is used to calculate the voltage deviation based on the reference voltage and the feedback voltage.

[0062] A deviation change rate calculation module is used to calculate the deviation change rate based on the voltage deviation.

[0063] The fuzzification processing module is used to fuzzify the voltage deviation and the deviation change rate to obtain the membership degree of the fuzzy variable E corresponding to the voltage deviation and the membership degree of the fuzzy variable EC corresponding to the deviation change rate.

[0064] The fuzzy decision module is used to make fuzzy decisions based on the membership degrees of the fuzzy variable E and the fuzzy variable EC, and obtain the fuzzy values ​​of the fuzzy output control parameters.

[0065] The defuzzification processing module is used to defuzzify the fuzzy values ​​of the fuzzy output control parameters to obtain the exact values ​​of the fuzzy output control parameters.

[0066] An execution module is used to correct the reference voltage based on the exact value of the fuzzy output control parameter;

[0067] The internal model control reference current calculation module is used to decouple and sum the corrected reference voltage to obtain the reference current for the internal model control of the current inner loop.

[0068] Preferably, the modulation signal module includes:

[0069] Modulation module 1 is used to convert the input reference voltage of the shore power inverter from two-phase rotating dq coordinates to three-phase rotating abc coordinates;

[0070] Modulation module 2 is used to modulate the input reference voltage of the shore power inverter in the three-phase rotating abc coordinate system with a triangular carrier wave to generate the modulation signal of the shore power inverter.

[0071] Preferably, the grid-connected module includes:

[0072] The sampling module is used to send voltage regulation commands to the shore power supply system based on the sampling of the output voltage of the shore power inverter and the on-load output voltage of the ship generator.

[0073] The pre-synchronization module is used by the shore power supply system to send the voltage adjustment command to the shore power inverter for output voltage adjustment;

[0074] The grid connection execution module is used to connect to the grid when the output voltage of the shore power inverter is consistent with the on-load output voltage of the ship's generator.

[0075] Compared with the closest existing technology, the present invention has the following beneficial effects:

[0076] This invention provides a ship-to-shore power grid connection control method, comprising: sampling the output voltage of the shore power inverter and the on-load output voltage of the ship generator, and performing grid connection after the grid connection conditions are met; after grid connection, using fuzzy internal model control based on droop control to adjust the output of the shore power inverter to complete the flexible ship-to-shore grid connection. This invention uses fuzzy internal model control based on droop control to adjust the output of the shore power inverter, which simplifies the controller parameter design, improves the control accuracy, grid connection voltage and frequency stability, and improves the system robustness. Attached Figure Description

[0077] Figure 1 A schematic diagram of a ship-shore power grid connection control method provided by the present invention;

[0078] Figure 2 A schematic diagram of a ship-shore power grid connection control system provided by the present invention;

[0079] Figure 3 This is an overall block diagram of the ship-shore power grid connection control system provided in the embodiments of the present invention;

[0080] Figure 4 This is a schematic diagram of the output adjustment process of the inverter device provided in an embodiment of the present invention;

[0081] Figure 5 This is a block diagram of the three-phase inverter bridge control provided in an embodiment of the present invention;

[0082] Figure 6 The present invention provides a block diagram and steps for a fuzzy PI control system.

[0083] Figure 7 This is a block diagram of the d-axis control of the internal mold control system provided in an embodiment of the present invention;

[0084] Figure 8 This refers to the DC-side output voltage under the conventional droop control method provided in this embodiment of the invention.

[0085] Figure 9 The DC-side output voltage of the fuzzy-internal model dual-loop control method based on the droop principle provided in this embodiment of the invention;

[0086] Figure 10 The grid-connected voltage frequency under the conventional droop control method provided in this embodiment of the invention;

[0087] Figure 11 The grid-connected voltage frequency is provided in the embodiment of the present invention using the fuzzy-internal model dual-loop control method based on the drooping principle.

[0088] Figure 12 The inverter-side grid-connected voltage is provided in the embodiment of the present invention using the fuzzy-internal model dual-loop control method based on the droop principle.

[0089] Figure 13 The active power output on the inverter side is provided by the fuzzy-internal model dual-loop control method based on the drooping principle in the embodiments of the present invention. Detailed Implementation

[0090] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0091] Example 1:

[0092] This invention discloses a ship-to-shore power grid connection control method, such as... Figure 1 As shown, it includes:

[0093] S1 samples the output voltage of the shore power inverter and the on-load output voltage of the ship generator, and performs grid connection after the grid connection conditions are met.

[0094] After S2 is connected to the grid, fuzzy internal model control based on droop control is used to adjust the output of the shore power inverter, completing the flexible grid connection between ship and shore. Figure 4 As shown, it specifically includes:

[0095] S2-1 samples the grid-connected voltage (i.e., the output voltage of the shore power inverter) and the output current of the shore power inverter to obtain Uo and io, which are used as inputs to the power calculation module to obtain the active power P and reactive power Q. The power calculation is shown in equation (1):

[0096]

[0097] In the formula, u od u oq These are the d-axis and q-axis components of Uo in the two-phase rotating dq reference coordinate system, respectively; i od i oq These represent the d-axis and q-axis components of io in the two-phase rotating dq reference coordinate system, respectively.

[0098] S2-2 inputs the active power P and reactive power Q output from the power calculation module into the droop control module to obtain the reference voltage U of the outer loop of the inverter side voltage of the shore power unit. abc_ref The droop characteristic equations of the droop control module are shown in equations (2) and (3):

[0099] ff _ref =-m(PP) _ref (2)

[0100] UU _ref =-n(QQ) _ref (3)

[0101] In the formula, f _ref P is the rated output frequency of the inverter side of the shore power unit, f is the output frequency of the inverter side of the shore power unit, and P is the rated output frequency of the inverter side of the shore power unit. _ref Let P be the active power output of the shore power unit at the inverter side at the rated frequency, m be the frequency droop coefficient, and U be the actual active power output of the shore power unit at the inverter side. _ref U is the rated three-phase output voltage on the inverter side of the shore power unit, and Q is the rated three-phase output voltage on the inverter side of the shore power unit. _ref Q represents the reactive power output from the inverter side of the shore power unit at rated voltage, and n represents the actual reactive power output from the inverter side of the shore power unit.

[0102] This is used to obtain the reference voltage U for droop control (i.e., the reference voltage of the outer loop of the inverter side voltage) based on the output frequency and voltage value of the shore power inverter. abc_ref ;

[0103] S2-3 Input the inverter-side output voltage Uo sampled in step S2-1 into the three-phase PLL phase-locked loop to obtain the phase and frequency f of the inverter-side output voltage Uo.

[0104] S2-4 Based on the outer loop reference voltage U of the inverter side voltage of the shore power device obtained in step S2-2 abc_ref The phase and frequency f of the inverter-side output voltage Uo obtained in steps S2-3 are used to compare the inverter-side voltage outer loop reference voltage U. abc_ref Perform a two-phase rotating dq coordinate system transformation to obtain the corresponding d-axis and q-axis reference input U of the fuzzy PI voltage outer loop control module. d_ref with U q_ref The inverter-side output voltage Uo sampled in step S2-1 is transformed into a two-phase rotating dq coordinate system to obtain its corresponding d-axis and q-axis fuzzy PI voltage outer loop control module feedback input u. od with u oq , will U d_ref with u od Similarly, U q_ref with u oq The difference between these two deviations is used as the inputs to the d-axis and q-axis fuzzy PI controllers, respectively. After fuzzy correction, the fuzzy PI voltage controllers obtain the reference values ​​i for the corresponding d-axis and q-axis filter capacitor currents, respectively. d_ref and i q_ref .

[0105] S2-5 samples the filter capacitor current to obtain the current filter capacitor current i. c Based on the current filter capacitor current i c The phase and frequency f of the inverter-side output voltage Uo obtained in step S2-3 are used to determine the current filter capacitor current i. c The feedback values ​​i of the filter capacitor current along the d-axis and q-axis are obtained through a two-phase rotating dq coordinate transformation. d and i q The feedback value i of the filter capacitor current on the d-axis and q-axis d with i q The reference values ​​i of the d-axis and q-axis filter capacitor currents obtained in step S2-4 d_ref and i q_refAs the feedback input and reference input of the inner loop module of the capacitor current inner model, the reference output voltage of the grid-connected inverter is obtained after passing through the equivalent feedback controller of the inner model control. The control signal for controlling the switching transistors of the grid-connected inverter bridge is generated by PWM control. The grid-connected output voltage is thus regulated by controlling the on and off of the three-phase inverter bridge switching transistors through the generated signal.

[0106] S2-4 further includes the following sub-steps as follows: Figure 6 As shown:

[0107] S2-4-1 uses the reference input as the given value and the feedback input of the controlled object as the reference value. The difference between the given value and the reference value is the voltage deviation e. The derivative of the voltage deviation e is the voltage deviation change rate ec. The voltage deviation e and the voltage deviation change rate ec are input into the fuzzification processing module. After fuzzification processing, E and EC corresponding to the domain of the rank quantity are obtained. The fuzzy set {NB,NM,NS,ZO,PS,PM,PB} is selected, and an appropriate membership function is selected to obtain the membership degree of E and EC.

[0108] S2-4-2 Inputs the membership degrees of E and EC into the fuzzy decision module, uses the Mamdani fuzzy inference method, and performs fuzzy control logic decision according to the fuzzy control rules to obtain the fuzzy output K. P_fuzzy and K I_fuzzy The corresponding membership degree;

[0109] S2-4-3 will output fuzzy K P_fuzzy and K I_fuzzy The corresponding membership degree input defuzzification processing module uses the area centroid averaging method for defuzzification processing to obtain the output quantity K in the exact quantity universe. P and K I Thus, the control output ΔK under fuzzy control is obtained. P and ΔK I This leads to the corrected fuzzy PI controller output quantity K. P =K P_pi +ΔK P and K I =K I_pi +ΔK I ;

[0110] S2-4-4 corrects the reference voltage based on Kp+Ki / s, and then decouples and sums the corrected reference voltages to obtain the reference current for the inner loop inner mode control, which is then input into the inner mode control module.

[0111] The fuzzy control rules corresponding to the proportional element P control in S2-4-2 are as follows:

[0112]

[0113] The fuzzy control rules corresponding to the proportional element I control in S2-4-2 are as follows:

[0114]

[0115] S2-5 further includes the following sub-steps:

[0116] Establish the d-axis control of the generalized controlled object, as shown in equation (4):

[0117]

[0118] The feedforward term for the internal model controller is:

[0119]

[0120] The feedback equivalent inner loop system controller is:

[0121]

[0122] In equation (4-6), K PWM For voltage gain, L1 is the first filter inductor corresponding to the filter, L2 is the second filter inductor corresponding to the filter, C is the filter capacitor corresponding to the filter, a is the internal mode controlled low-pass filter time constant, S is the differential operator, and G is the voltage gain. C (S) is the equivalent feedback loop controller obtained from the internal model controller, G LMC (S) represents the internal mold controller corresponding to the d-axis structure control block diagram, such as... Figure 7 As shown.

[0123] In the actual debugging process, you can first assume that the model is error-free and debug 'a' to optimize the controller's tracking performance.

[0124] Example 2:

[0125] This invention discloses a ship-to-shore power grid connection control system, such as... Figure 2 As shown, it includes:

[0126] The grid connection module is used to sample the output voltage of the shore power inverter and the on-load output voltage of the ship generator, and to connect to the grid after the grid connection conditions are met.

[0127] The adjustment module is used to adjust the output of the shore power inverter after grid connection by using fuzzy internal model control based on droop control, so as to complete the flexible grid connection between ship and shore.

[0128] Preferably, the adjustment module includes:

[0129] The fuzzy control input calculation module is used to calculate the reference voltage and feedback voltage for fuzzy voltage outer loop control based on the output voltage and current of the shore power inverter.

[0130] The inner model control input calculation module 1 is used to calculate the reference current of the inner model control of the current inner loop based on the reference voltage and feedback voltage of the outer loop control of the fuzzy voltage.

[0131] The inner model control input calculation module 1 is used to calculate the feedback current of the inner model control of the current inner loop based on the capacitor current of the filter device behind the inverter.

[0132] The inner model control module is used to input the reference current and feedback current of the inner current loop inner model control into the inner current loop inner model controller to obtain the input reference voltage of the shore power inverter.

[0133] The modulation signal module generates the modulation signal of the shore power inverter based on the input reference voltage of the shore power inverter.

[0134] The output adjustment module is used to adjust the output of the shore power inverter device by means of the modulation signal of the shore power inverter device.

[0135] Preferably, the fuzzy control input calculation module includes:

[0136] The phase-locked loop (PLL) calculation module is used to input the output voltage of the shore power inverter into the PLL to obtain the frequency and phase of the output voltage.

[0137] The power calculation module is used to calculate the corresponding active and reactive power based on the output voltage and current of the shore power inverter.

[0138] The droop control module 1 is used to input the active power and reactive power into the droop characteristic equation to obtain the output frequency and voltage value of the shore power inverter.

[0139] The droop control module 2 is used to obtain a reference voltage for droop control based on the output frequency and voltage value of the shore power inverter.

[0140] The reference voltage coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the droop control reference voltage based on the frequency and phase of the output voltage, so as to obtain the reference voltage of the d-axis and q-axis as the reference voltage for the fuzzy voltage outer loop control.

[0141] The coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the output voltage of the shore power inverter to obtain the output voltage of the d-axis and q-axis as the feedback voltage for fuzzy voltage outer loop control.

[0142] Preferably, the internal model control input calculation module 1 includes:

[0143] The voltage deviation calculation module is used to calculate the voltage deviation based on the reference voltage and the feedback voltage.

[0144] A deviation change rate calculation module is used to calculate the deviation change rate based on the voltage deviation.

[0145] The fuzzification processing module is used to fuzzify the voltage deviation and the deviation change rate to obtain the membership degree of the fuzzy variable E corresponding to the voltage deviation and the membership degree of the fuzzy variable EC corresponding to the deviation change rate.

[0146] The fuzzy decision module is used to make fuzzy decisions based on the membership degrees of the fuzzy variable E and the fuzzy variable EC, and obtain the fuzzy values ​​of the fuzzy output control parameters.

[0147] The defuzzification processing module is used to defuzzify the fuzzy values ​​of the fuzzy output control parameters to obtain the exact values ​​of the fuzzy output control parameters.

[0148] An execution module is used to correct the reference voltage based on the exact value of the fuzzy output control parameter;

[0149] The internal model control reference current calculation module is used to decouple and sum the corrected reference voltage to obtain the reference current for the internal model control of the current inner loop.

[0150] Preferably, the modulation signal module includes:

[0151] Modulation module 1 is used to convert the input reference voltage of the shore power inverter from two-phase rotating dq coordinates to three-phase rotating abc coordinates;

[0152] Modulation module 2 is used to modulate the input reference voltage of the shore power inverter in the three-phase rotating abc coordinate system with a triangular carrier wave to generate the modulation signal of the shore power inverter.

[0153] Preferably, the grid-connected module includes:

[0154] The sampling module is used to send voltage regulation commands to the shore power supply system based on the sampling of the output voltage of the shore power inverter and the on-load output voltage of the ship generator.

[0155] The pre-synchronization module is used by the shore power supply system to send the voltage adjustment command to the shore power inverter for output voltage adjustment;

[0156] The grid connection execution module is used to connect to the grid when the output voltage of the shore power inverter is consistent with the on-load output voltage of the ship's generator.

[0157] Example 3:

[0158] This embodiment uses the MATLAB / SIMULINK platform to simulate and design a ship-to-shore power grid connection control method and system proposed in this invention. This embodiment uses a high-voltage onboard method (6.6KV / 60Hz) for ship-to-shore power grid connection control to build a model and perform simulation verification. Figure 3 The diagram shows the overall block diagram of the ship-to-shore power grid connection control system. The specific process is as follows: The land grid voltage (10KV / 50Hz) is stepped down and filtered, then used as the input to a three-phase rectifier bridge, outputting a DC voltage. This DC voltage serves as the input to a three-phase inverter bridge. After passing through the inverter bridge and filtering device, it becomes a frequency-converted and voltage-transformed three-phase AC power. This AC power is then transformed to obtain the desired three-phase voltage and connected to the bus. The output voltages on both the ship side and the shore power inverter side are sampled, collecting voltage amplitude, phase, and frequency. Synchronization of frequency, phase, and voltage is achieved to meet the grid connection conditions, allowing the ship's electrical system to connect to the shore power grid. Finally, the ship's generator is disconnected, and the load is supplied by shore power.

[0159] Figure 4 , Figure 5 The diagrams show the output regulation process of the inverter and the control block diagram of the three-phase inverter bridge. The specific process is as follows: The inverter output voltage and current are sampled by the measurement module. The frequency and phase of the inverter output voltage are acquired by a three-phase PLL phase-locked loop. The sampled voltage and current are used as inputs to the power calculation module. Power calculation requires a transformation from a three-phase rotating coordinate system to a two-phase rotating coordinate system. The outputs of the power calculation module, i.e., active power and reactive power, are substituted into the droop characteristic equation (Pf, QU) to obtain the three-phase reference voltage. This three-phase rotating coordinate system is then transformed back to a two-phase rotating coordinate system, and the transformed reference voltage serves as the reference input for the fuzzy PI voltage outer loop control. The sampled inverter output voltage is transformed back to a two-phase rotating coordinate system and used as the feedback input for the fuzzy PI voltage outer loop control. The output of the fuzzy PI voltage outer loop control serves as the reference input for the capacitor current inner loop control. The sampled filter capacitor current is transformed back to a two-phase rotating coordinate system and used as the feedback input for the capacitor current inner loop control. The output controlled by the capacitor current inner loop is transformed from a two-phase rotating coordinate system to a three-phase rotating coordinate system to become a modulation signal. This signal is modulated with a triangular carrier wave to produce the desired modulation signal, which is used to control the on / off state of the inverter bridge switching transistors. The specific three-phase inverter bridge control block diagram is as follows: Figure 5 As shown.

[0160] Figure 6 The diagram shows the block diagram and steps of the fuzzy PI control system. The inverter output voltage, obtained based on the droop principle, is used as the reference value for the fuzzy PI voltage loop. The PI parameters are updated in real time through fuzzy inference. Specifically, the fuzzy self-tuning PID control uses the voltage deviation U... E and the rate of change of deviation U ECAs input to the fuzzy controller, the PID parameter K is used. p K i As an output, the fuzzy controller is currently in a two-input, two-output state. During commissioning and operation, the voltage deviation and its rate of change are detected in real time. Fuzzy inference is used to calculate and decide on the two output control parameters to meet the control requirements. The FLC rule is a judgment criterion summarized by experienced personnel, generally expressed in the form of an "if-then" statement. The rule form selected in this paper is: if A and B then C.

[0161] Comparison of DC-side output curves under different control strategies: such as Figure 8 As shown, the DC-side output voltage regulation time under the traditional droop control method is approximately 0.3 seconds. Figure 9 As shown, the DC-side output voltage regulation time under the fuzzy-internal model dual-loop control method based on the droop principle is about 0.14s, and the dynamic response is fast, thus providing a stable DC voltage for the grid-connected inverter stage.

[0162] Comparison of grid-connected voltage-frequency curves under different control strategies: such as Figure 10 As shown, the grid-connected voltage frequency is relatively unstable under the traditional droop control method, with a maximum frequency deviation of approximately 0.17Hz. Figure 11 As shown, the grid-connected voltage frequency fluctuates slightly from the moment of grid connection under the fuzzy-internal model dual-loop control method based on the droop principle, but recovers to stability relatively quickly, and has good robustness.

[0163] Figure 12 The figure shows the inverter-side grid-connected voltage waveform under the fuzzy-internal model dual-loop control method based on the droop principle. The circuit breaker closes in approximately 0.7 seconds, and the grid-connected voltage waveform stabilizes after closing, with a total harmonic content of approximately 0.07% and no significant voltage distortion.

[0164] Figure 13 The figure shows the active power output curve of the inverter side during grid connection under the fuzzy-internal model dual-loop control method based on the droop principle. The active power gradually increases to 1.5MW and stabilizes from 0.7s after closing.

[0165] The simulation results show that the present invention uses fuzzy internal model control based on droop control to adjust the output of the shore power inverter, which simplifies the controller parameter design, improves the control accuracy, grid voltage and frequency stability, and improves the system robustness.

[0166] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0167] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0168] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0169] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit its protection scope. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims pending approval.

Claims

1. A ship-to-shore power grid connection control method, characterized in that, include: The output voltage of the shore power inverter and the on-load output voltage of the ship generator are sampled, and grid connection is carried out after the grid connection conditions are met. After grid connection, fuzzy internal model control based on droop control is used to adjust the output of the shore power inverter to complete the flexible grid connection between ship and shore. The method of adjusting the output of the shore power inverter using fuzzy internal model control based on droop control includes: Based on the output voltage and current of the shore power inverter, the reference voltage and feedback voltage of the fuzzy voltage outer loop control are calculated. Based on the reference voltage and feedback voltage of the outer loop control of the fuzzy voltage, the reference current of the inner loop control of the current is calculated. Based on the capacitor current of the filter device on the back side of the inverter, calculate the feedback current of the inner loop inner mode control. The reference current and feedback current of the inner current loop control are input into the inner current loop controller to obtain the input reference voltage of the shore power inverter. Based on the input reference voltage of the shore power inverter, a modulation signal for the shore power inverter is generated; The output of the shore power inverter is adjusted by the modulation signal of the shore power inverter. The calculation of the reference voltage and feedback voltage for fuzzy voltage outer loop control based on the output voltage and current of the shore power inverter includes: The output voltage of the shore power inverter is input into the phase-locked loop to obtain the frequency and phase of the output voltage. Calculate the corresponding active power and reactive power based on the output voltage and current of the shore power inverter. The active power and reactive power are input into the droop characteristic equation to obtain the output frequency and voltage value of the shore power inverter. Based on the output frequency and voltage value of the shore power inverter, the reference voltage for droop control is obtained; Based on the frequency and phase of the output voltage, the droop control reference voltage is transformed into two-phase rotating dq coordinates to obtain the reference voltages of the d-axis and q-axis, which are used as the reference voltages for the fuzzy voltage outer loop control. The output voltage of the shore power inverter is subjected to a two-phase rotating dq coordinate transformation to obtain the output voltages of the d-axis and q-axis, which are used as the feedback voltages for fuzzy voltage outer loop control.

2. The method as described in claim 1, characterized in that, The droop characteristic equation is as follows: f-f _ref =-m(P-P _ref ) U-U _ref =-n(Q-Q _ref ) Among them, f _ref Here, f is the rated output frequency of the shore power inverter, m is the frequency droop coefficient, and P is the actual output active power of the shore power inverter. _ref U is the output active power of the shore power inverter at rated frequency; U is the three-phase output voltage of the shore power inverter. _ref Let n be the rated three-phase output voltage of the shore power inverter, n be the voltage droop characteristic coefficient, and Q be the actual output reactive power of the shore power inverter. _ref This refers to the reactive power output of the shore power inverter at the rated frequency.

3. The method as described in claim 1, characterized in that, The calculation of the reference current for the inner-loop model control of the current based on the reference voltage and feedback voltage of the outer-loop fuzzy voltage control includes: Calculate voltage deviation based on reference voltage and feedback voltage; Calculate the rate of change of deviation based on the voltage deviation; The voltage deviation and the rate of change of deviation are fuzzified to obtain the membership degree of the fuzzy variable E corresponding to the voltage deviation and the membership degree of the fuzzy variable EC corresponding to the rate of change of deviation. Based on the membership degrees of the fuzzy variable E and the fuzzy variable EC, a fuzzy decision is made to obtain the fuzzy value of the fuzzy output control parameter. The fuzzy values ​​of the fuzzy output control parameters are defuzzified to obtain the exact values ​​of the fuzzy output control parameters. The reference voltage is corrected based on the exact value of the fuzzy output control parameter. The modified reference voltages are decoupled and summed to obtain the reference current for the inner loop inner mode control.

4. The method as described in claim 1, characterized in that, The current inner loop internal model controller model is as follows: Among them, G C (S) is the equivalent feedback loop controller obtained from the internal model controller, K PWM L1 is the voltage gain, L2 is the first filter inductor corresponding to the filter, C is the filter capacitor corresponding to the filter, a is the filter time constant of the internal mode control low-pass filter, and S is the differential operator.

5. The method as described in claim 1, characterized in that, The step of generating a modulation signal for the shore power inverter based on the input reference voltage of the shore power inverter includes: The input reference voltage of the shore power inverter is transformed from a two-phase rotating dq coordinate system to a three-phase rotating abc coordinate system. The input reference voltage of the shore power inverter in the three-phase rotating abc coordinate system is modulated with a triangular carrier wave to generate the modulation signal of the shore power inverter.

6. The method as described in claim 1, characterized in that, The output voltage of the shore power inverter and the on-load output voltage of the ship generator are sampled, and grid connection is performed after the grid connection conditions are met, including: Based on sampling of the output voltage of the shore power inverter and the on-load output voltage of the ship's generator, the shipside system sends voltage regulation commands to the shore power supply system. The shore power supply system sends the voltage regulation command to the shore power inverter to adjust the output voltage; When the output voltage of the shore power inverter is consistent with the on-load output voltage of the ship's generator, it is connected to the grid.

7. A ship-shore power grid connection control system, characterized in that, include: The grid connection module is used to sample the output voltage of the shore power inverter and the on-load output voltage of the ship generator, and to connect to the grid after the grid connection conditions are met. The adjustment module is used to adjust the output of the shore power inverter after grid connection by adopting fuzzy internal model control based on droop control, so as to complete the flexible grid connection between ship and shore. The adjustment module includes: The fuzzy control input calculation module is used to calculate the reference voltage and feedback voltage for fuzzy voltage outer loop control based on the output voltage and current of the shore power inverter. The inner model control input calculation module 1 is used to calculate the reference current of the inner model control of the current inner loop based on the reference voltage and feedback voltage of the outer loop control of the fuzzy voltage. The inner model control input calculation module 2 is used to calculate the feedback current of the inner model control of the current inner loop based on the capacitor current of the filter device behind the inverter. The inner model control module is used to input the reference current and feedback current of the inner current loop inner model control into the inner current loop inner model controller to obtain the input reference voltage of the shore power inverter. The modulation signal module generates the modulation signal of the shore power inverter based on the input reference voltage of the shore power inverter. The output adjustment module is used to adjust the output of the shore power inverter device through the modulation signal of the shore power inverter device; The fuzzy control input calculation module includes: The phase-locked loop (PLL) calculation module is used to input the output voltage of the shore power inverter into the PLL to obtain the frequency and phase of the output voltage. The power calculation module is used to calculate the corresponding active and reactive power based on the output voltage and current of the shore power inverter. The droop control module 1 is used to input the active power and reactive power into the droop characteristic equation to obtain the output frequency and voltage value of the shore power inverter. The droop control module 2 is used to obtain a reference voltage for droop control based on the output frequency and voltage value of the shore power inverter. The reference voltage coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the droop control reference voltage based on the frequency and phase of the output voltage, so as to obtain the reference voltage of the d-axis and q-axis as the reference voltage for the fuzzy voltage outer loop control. The coordinate transformation module is used to perform a two-phase rotating dq coordinate transformation on the output voltage of the shore power inverter to obtain the output voltage of the d-axis and q-axis as the feedback voltage for fuzzy voltage outer loop control.

8. The system as described in claim 7, characterized in that, The internal model control input calculation module 1 includes: The voltage deviation calculation module is used to calculate the voltage deviation based on the reference voltage and the feedback voltage. A deviation change rate calculation module is used to calculate the deviation change rate based on the voltage deviation. The fuzzification processing module is used to fuzzify the voltage deviation and the rate of change of deviation to obtain the membership degree of the fuzzy variable E corresponding to the voltage deviation and the membership degree of the fuzzy variable EC corresponding to the rate of change of deviation. The fuzzy decision module is used to make fuzzy decisions based on the membership degrees of the fuzzy variable E and the fuzzy variable EC, and obtain the fuzzy values ​​of the fuzzy output control parameters. The defuzzification processing module is used to defuzzify the fuzzy values ​​of the fuzzy output control parameters to obtain the exact values ​​of the fuzzy output control parameters. An execution module is used to correct the reference voltage based on the exact value of the fuzzy output control parameter; The internal model control reference current calculation module is used to decouple and sum the corrected reference voltage to obtain the reference current for the internal model control of the current inner loop.

9. The system as described in claim 7, characterized in that, The modulation signal module includes: Modulation module 1 is used to convert the input reference voltage of the shore power inverter from two-phase rotating dq coordinates to three-phase rotating abc coordinates; Modulation module 2 is used to modulate the input reference voltage of the shore power inverter in the three-phase rotating abc coordinate system with a triangular carrier wave to generate the modulation signal of the shore power inverter.

10. The system as described in claim 7, characterized in that, The grid connection module includes: The sampling module is used to send voltage regulation commands to the shore power supply system based on the sampling of the output voltage of the shore power inverter and the on-load output voltage of the ship generator. The pre-synchronization module is used by the shore power supply system to send the voltage regulation command to the shore power inverter for output voltage adjustment; The grid connection execution module is used to connect to the grid when the output voltage of the shore power inverter is consistent with the on-load output voltage of the ship's generator.

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