CN114679070A - Tidal energy control system and control method thereof - Google Patents

Tidal energy control system and control method thereof Download PDF

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CN114679070A
CN114679070A CN202210382382.3A CN202210382382A CN114679070A CN 114679070 A CN114679070 A CN 114679070A CN 202210382382 A CN202210382382 A CN 202210382382A CN 114679070 A CN114679070 A CN 114679070A
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power
boost converter
controller
input
converter circuit
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CN114679070B (en
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朱勇
戴瑜兴
彭子舜
赵振兴
刘增
杨亚超
聂鸿宇
王伟红
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SHENZHEN JINGQUANHUA ELECTRONICS CO LTD
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SHENZHEN JINGQUANHUA ELECTRONICS CO LTD
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/2173—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a biphase or polyphase circuit arrangement
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/561—Voltage to current converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider

Abstract

The invention discloses a tidal energy control system, which comprises a tidal energy power generation device, a hardware circuit topology and a control module, wherein the hardware circuit topology comprises an uncontrolled rectifying circuit and a Boost converter circuit, and the Boost converter circuit is connected with a hybrid semiconductor parallel device in parallel; the control module comprises a variable step length frequency self-adaptive filtering controller, a maximum power tracking controller and a high-performance prediction controller. The invention realizes the maximum power point capture of the output power by a self-adaptive maximum power control strategy, and simultaneously carries out smooth processing on the tidal energy output power on the premise of not losing too much power; the high-efficiency, low-harmonic-content and high-power-factor operation of the power converter is realized by establishing a cost function containing device loss, harmonic content and power factors through a high-performance predictive control method. Therefore, the tidal power generation device can meet the requirements of high performance and high stable power supply in the process of generating power on the sea island, the coast or the sea.

Description

Tidal energy control system and control method thereof
Technical Field
The invention relates to the technical field of power generation, in particular to a tidal energy control system and a control method thereof.
Background
With the increasing demand for the quality of electric energy of tidal power generation devices in the sea island, coast or sea, the demand for high performance and high stability power supply is becoming a trend in the development of tidal power generation devices. The achievement of this goal requires a higher performance control strategy. The application of the traditional maximum power tracking strategy in photovoltaic and wind power generation is well developed, however, due to the particularity of the marine environment, the change of the ocean current speed can cause the power of the water turbine to generate large fluctuation, wherein the expansion effect is the main reason for the current speed change. As disclosed in the prior art document cn201410622989.x, the conventional tip speed ratio maximum power point tracking algorithm requires frequent acceleration or deceleration of the water turbine under the expansion effect, which may cause severe fluctuation of the power of the generator, resulting in poor stability of the device. Meanwhile, the whole system is nonlinear, so that the output power factor of the water turbine is greatly influenced by the system and cannot meet the requirement of high-performance power supply. Thus. It is necessary to design a composite control method to overcome the disadvantages of the single control method.
In order to meet the requirements of the tidal energy and tidal energy power generation device on high performance and high stable power supply in the process of island, coast or sea power generation, the fluctuation of output power can be effectively reduced by combining with a self-adaptive filtering control strategy on the basis of maximum power tracking, and in order to further reduce the influence of system nonlinearity on high performance power supply, a fractional order model predictive control is adopted to improve the power factor output by a generator. However, the existing patent document CN 202111024969.9 discloses a fractional order virtual inertia prediction control battery test direct current microgrid voltage stabilization method, and the patent document CN201810018676.1 discloses an adaptive step size photovoltaic maximum power tracking method and system based on conductance increment, but there is no comprehensive analysis and research on the application of the composite control of adaptive filtering maximum power tracking and fractional order model prediction control in the tidal energy and tidal energy power generation device.
Disclosure of Invention
In view of the deficiencies of the prior art, it is an object of the present invention to provide a tidal energy control system and a control method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
a tidal energy control system comprises a tidal energy power generation device, a hardware circuit topology and a control module, wherein the hardware circuit topology comprises an uncontrolled rectifying circuit and a Boost converter circuit, and the Boost converter circuit is connected with a hybrid semiconductor parallel device in parallel; the control module comprises a variable step length frequency self-adaptive filtering controller, a maximum power tracking controller and a high-performance prediction controller;
the tidal power generation device is connected with the input end of the uncontrolled rectifying circuit, the output end of the uncontrolled rectifying circuit is connected with the input end of the Boost converter circuit, the output end of the Boost converter circuit is connected with the input end of the variable step frequency self-adaptive filtering controller, the output end of the variable step frequency self-adaptive filtering controller is connected with the input end of the maximum power tracking controller, the output end of the maximum power tracking controller is connected with the input end of the high-performance prediction controller, and the output end of the high-performance prediction controller is connected with the hybrid semiconductor parallel device;
the uncontrolled rectifying circuit is used for converting alternating voltage into direct voltage, the control module enables output voltage and current of the Boost converter circuit to be relatively stable by adjusting connection or disconnection of the hybrid semiconductor parallel device, the variable step frequency self-adaptive filtering controller and the maximum power tracking controller are used for reducing fluctuation of output power of the tidal power generation device, and the high-performance prediction controller is used for improving power factor output by the tidal power generation device.
Further, the tidal power generation device comprises a horizontal-axis water turbine and a permanent magnet generator, wherein the horizontal-axis water turbine is connected with the permanent magnet generator through a rotating shaft.
Further, the uncontrolled rectifying circuit is a three-phase uncontrolled rectifying circuit, the Boost converter circuit is a two-level Boost converter circuit, and the hybrid semiconductor parallel device is an IGBT/MOSFET hybrid device.
Further, the method for performing variable-step frequency adaptive filtering control based on the variable-step frequency adaptive filtering controller comprises the following steps: adjusting the frequency of an input digital filter in a variable step size frequency adaptive filter controller according to the gradient change of the output power of a Boost converter circuit to the input current frequency of the Boost converter circuit, and adopting a small step size when the gradient is increased; otherwise, large step length is adopted, and the self-carrying interference frequency of the tidal electric energy is filtered; the filtering of the low-order harmonic of the output current of the Boost converter circuit is realized, and the power quality is improved.
Further, the digital filter is a first order digital filter, the input end of the first order digital filter is composed of a current/voltage signal and a cut-off frequency signal, the output is a filtering signal, and the transfer function of the filtering signal is
Figure BDA0003593417240000031
Further, the specific steps of performing the variable-step frequency adaptive filtering control are as follows:
s01, an initial program is started to detect the voltage Ut and the current It of the output side of the Boost converter and set the initial frequency to be 0.07HZ, and the power Pt of the output side is calculated;
s02, calculating an output-side power, an increment Δ Pt ═ Pt (k) -Pt (k-1) of an output power Pt (k) at the time point to an output power Pt (k-1) at the previous time point, and an increment Δ ft ═ ft (k) -ft (k-1) of a cutoff frequency ft (k) at the time point to a duty ratio ft (k-1) at the previous time point, from a formula Pt ═ Ut ═ It;
s03, determining whether the increments Δ Pt and Δ ft are in the same direction, that is, determining whether both Δ Pt and Δ ft are greater than 0 or less than 0, if so, making the cutoff frequency ft (k +1) ft (k) + ftstep for the next cycle, and then returning to step S01; otherwise, go to step S04;
s04, determine whether the increments Δ Pt and Δ ft are reversed, if yes, make the cutoff frequency ft (k +1) of the next cycle ft (k) -ftstep, and then return to step S01.
Further, the method for performing maximum power tracking control based on the maximum power tracking controller comprises the following steps: controlling the gradient change of the duty ratio according to the input power of the Boost converter circuit, and adjusting the I of the inductive current by increasing the input voltage signal of the Boost converter circuitLMagnitude, the input voltage signal increases by one step as the gradient increases; otherwise, reducing one step length to realize maximum power tracking on the input power of the front end of the Boost converter circuit.
Further, the specific steps of performing maximum power tracking control are as follows:
s11, detecting input side voltage V of boost converter by starting initial programinInput current ILOutput side voltage UtAnd the output side current ItCalculating the input side power Pin；
S12, formula Pin＝Uin*ILCalculating the input side power Pin(k) For the input power P at the previous momentinIncrement of (k-1) (. DELTA.P)inDuty ratio D (k) at the time point to duty ratio D at the previous time pointtIncrement of (k-1) (. DELTA.D)t＝Dt(k)-Dt(k-1); meterCalculating the input voltage signal V at that momentin(k) Step length of (2)
Figure BDA0003593417240000041
S13, judging the increment delta PinAnd Δ DtWhether or not in the same direction, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)>Dt(k-1), or Pin(k)<PinSimultaneous production of (k-1) and Dt(k)<Dt(k-1), if yes, making the input voltage signal V of the next periodin(k+1)＝Vin(k)+Vin_stepSubsequently, return is made to step S11; otherwise, go to step S14;
s14, judging the increment delta PinWhether or not Δ Dt is reversed, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)<Dt(k-1), or Pin(k)<PinSimultaneous D of (k-1)t(k)>Dt(k-1), if yes, the input voltage signal V of the next period is orderedin(k+1)＝Vin(k)-Vin_stepSubsequently, it returns to step S11.
Further, the method for performing high-performance predictive control based on the high-performance predictive controller comprises the following steps: by establishing a fractional order differential equation reflecting the inductive current in the two-level Boost converter circuit in the two states of the switch of the hybrid parallel device, substituting the fractional order differential equation into the cost function to obtain the inductive current predicted value in the corresponding switch state, the inductive current signal of the two-level Boost converter circuit can accurately track the reference current signal after n switching periods are finished.
Further, the specific steps for performing high performance predictive control are as follows:
s31, reading the output voltage signal V0(k)、IL(k)、Vin(k)、IL3*(K+1)、IL4*(K+1)；
S32, calculating a cost function C1 in the on state of the switch of the hybrid combiner and a cost function C2 in the off state of the switch of the hybrid combiner;
s33, judging the sizes of C1 and C2, and if C2 is larger than C1, leading edge pulse is generated; otherwise the falling edge pulse.
The invention has the beneficial effects that:
(1) due to the adoption of a maximum power tracking control strategy, the maximum power tracking of the input side can be realized, and the energy loss is reduced.
(2) Due to the adoption of the self-adaptive filtering control strategy, the fluctuation of the output power of the system can be effectively stabilized, and the stability of the system is improved.
(3) On the basis of combining the maximum power tracking and the adaptive filtering control strategy, the influence of system nonlinearity on high-performance power supply is reduced.
Drawings
FIG. 1 is a schematic view of a tidal energy control apparatus framework of the present invention;
FIG. 2 is a flow chart of the control steps of a variable step frequency adaptive filtering controller in a tidal energy control system according to the present invention;
FIG. 3 is a flow chart of the control steps of a maximum power tracking controller in a tidal energy control system according to the present invention;
FIG. 4 is a flow chart of the control steps of a high performance predictive controller in a tidal energy control System according to the present invention;
FIG. 5 is a flow chart of the control principle of a high performance predictive controller in a tidal energy control System according to the present invention.
Detailed Description
The invention will be further described with reference to the accompanying drawings and the detailed description below:
as shown in fig. 1, a tidal energy control system comprises a tidal energy power generation device, a hardware circuit topology and a control module, wherein the hardware circuit topology comprises an uncontrolled rectifying circuit and a Boost converter circuit, and the Boost converter circuit is connected with a hybrid semiconductor parallel device in parallel; the control module comprises a variable step length frequency self-adaptive filtering controller, a maximum power tracking controller and a high-performance prediction controller;
the tidal power generation device is connected with the input end of the uncontrolled rectifying circuit, the output end of the uncontrolled rectifying circuit is connected with the input end of the Boost converter circuit, the output end of the Boost converter circuit is connected with the input end of the variable step length frequency self-adaptive filtering controller, the output end of the variable step length frequency self-adaptive filtering controller is connected with the input end of the maximum power tracking controller, the output end of the maximum power tracking controller is connected with the input end of the high-performance prediction controller, and the output end of the high-performance prediction controller is connected with the hybrid semiconductor parallel device;
the uncontrolled rectifying circuit is used for converting alternating voltage into direct voltage, the control module enables output voltage and current of the Boost converter circuit to be relatively stable by adjusting connection or disconnection of the hybrid semiconductor parallel device, the variable step frequency self-adaptive filtering controller and the maximum power tracking controller are used for reducing fluctuation of output power of the tidal power generation device, and the high-performance prediction controller is used for improving power factor output by the tidal power generation device.
The tidal power generation device comprises a horizontal shaft water turbine and a direct-drive permanent magnet generator, wherein the horizontal shaft water turbine is connected with the permanent magnet generator through a rotating shaft, and the energy transmission efficiency is improved.
The uncontrolled rectifying circuit is a three-phase uncontrolled rectifying circuit, the Boost converter circuit is a two-level Boost converter circuit, and the hybrid semiconductor parallel device is an IGBT/MOSFET hybrid device. Two-level Boost converter circuits are the most common and simple, with a small number of components and low cost. The circuit voltage is not high and does not need multi-level to improve the voltage endurance value. The Si IGBT/SiC MOSFET hybrid device is formed by connecting a large-capacity Si IGBT and a small-capacity SiC MOFET with a faster switching speed in parallel.
The method for controlling the variable-step-size frequency adaptive filtering based on the variable-step-size frequency adaptive filtering controller comprises the following steps: adjusting the frequency of an input digital filter in a variable step frequency self-adaptive filter controller according to the gradient change of the output power of a Boost converter circuit to the input current frequency of the Boost converter circuit, and adopting small step when the gradient is increased; otherwise, large step length is adopted, and the self-carrying interference frequency of the tidal electric energy is filtered; the filtering of low-order harmonic waves of output current of a Boost converter circuit is realized, and the power quality is improved;
the digital filter is a first-order digital filter, the input end of the first-order digital filter consists of a current/voltage signal and a cut-off frequency signal, the output of the first-order digital filter is a filtering signal, and the transfer function of the filtering signal is
Figure BDA0003593417240000071
The transfer function adopts a bilinear transformation method, s is a differential operator in a pull-type transformation, and w is 2 pi f and represents the turning frequency.
The step adjustment changes the value of delta ft to play the role of peak clipping and valley filling of power, small step is slowly increased when approaching the peak value, and large step is quickly adjusted back after crossing the peak value. The purpose of step size adjustment is to minimize the attenuation of the filtered harmonic content to the maximum power point, and further filter the self-contained interference frequency of tidal electric energy. The large step size range is 0.5 e-5-2 e-5, and the small step size is a simulation minimum step size unit eps.
The specific steps for performing the step-size-variable frequency adaptive filtering control are shown in fig. 2:
s01, an initial program is started to detect the voltage Ut and the current It of the output side of the Boost converter and set the initial frequency to be 0.07HZ, and the power Pt of the output side is calculated;
s02, calculating an output-side power from the expression Pt ═ Ut It, an increment Δ Pt ═ Pt (k) -Pt (k-1) of the output power Pt (k-1) at the previous time, and an increment Δ ft ═ ft (k) -ft (k-1) of the cutoff frequency ft (k) at the previous time, from the expression Pt ═ It;
s03, determining whether the increments Δ Pt and Δ ft are in the same direction, that is, determining whether both Δ Pt and Δ ft are greater than 0 or less than 0, if so, making the cutoff frequency ft (k +1) ft (k) + ftstep for the next cycle, and then returning to step S01; otherwise, go to step S04; ftstep is the step size of a frequency change single step. At this time, the value of ftstep adopts a large step range, and the large step is added to the equidirectional frequency;
s04, determine whether the increments Δ Pt and Δ ft are reversed, if yes, make the cutoff frequency ft (k +1) of the next cycle ft (k) -ftstep, and then return to step S01. At this time, the value of ftstep is in a range of small step size, and the small step size is subtracted from the equidirectional frequency.
The method for carrying out maximum power tracking control based on the maximum power tracking controller comprises the following steps: controlling the gradient change of the duty ratio according to the input power of the Boost converter circuit, and adjusting the I of the inductive current by increasing the Boost input voltage signalLMagnitude, the input voltage signal increases by one step as the gradient increases; otherwise, one step is reduced, and maximum power tracking of the input power of the front end of the Boost converter circuit is achieved.
The specific steps for maximum power tracking control are shown in fig. 3:
s11, detecting input side voltage V of boost converter by starting initial programinInput current ILOutput side voltage UtAnd the output side current ItCalculating the input side power Pin；
S12, formula Pin＝Uin*ILCalculating the input side power Pin(k) For the input power P at the previous momentinIncrement of (k-1) (. DELTA.P)inDuty ratio D (k) at the time point to duty ratio D at the previous time pointtIncrement of (k-1) < delta > Dt＝Dt(k)-Dt(k-1); calculating the input voltage signal V at that momentin(k) Step length of (2)
Figure BDA0003593417240000081
S13, judging the increment delta PinAnd Δ DtWhether or not in the same direction, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)>Dt(k-1), or Pin(k)<PinSimultaneous D of (k-1)t(k)<Dt(k-1), if yes, making the input voltage signal V of the next periodin(k+1)＝Vin(k)+Vin_stepSubsequently, return is made to step S11; otherwise, go to step S14;
s14, judging the increment delta PinWhether or not Δ Dt is reversed, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)<Dt(k-1), or Pin(k)<Pin(k-1) same asTime Dt(k)>Dt(k-1), if yes, the input voltage signal V of the next period is orderedin(k+1)＝Vin(k)-Vin_stepSubsequently, it returns to step S11.
The variable step frequency adaptive filtering control method and the maximum power tracking control method are combined to form an adaptive maximum power control strategy, the adaptive maximum power control strategy realizes maximum power point capture of output power by adopting an improved disturbance observation method based on an adaptive inertia link, and meanwhile, the tidal energy output power is smoothly processed on the premise of not losing too much power, so that ripple current is reduced.
The high-performance predictive control method provided by the invention realizes the high-efficiency, low-harmonic-content and high-power-factor operation of the power converter by establishing the cost function containing device loss, harmonic content and power factors, and improves the current precision.
The method for performing high-performance predictive control based on the high-performance predictive controller comprises the following steps: by establishing a fractional order differential equation reflecting the inductive current in the two-level Boost converter circuit in the two states of the on state and the off state of the switch of the hybrid semiconductor parallel device and substituting the fractional order differential equation into the cost function, the inductive current predicted value in the corresponding switch state is obtained, and the purpose that the inductive current signal can accurately track the reference current signal after the two-level Boost converter circuit finishes n switching periods is achieved.
The specific steps for performing high performance predictive control are shown in fig. 4:
s31, reading the output voltage signal V0(k) Inductor current IL(k)、Vin(k)、IL3*(K+1)、IL4*(K+1)；
V0(k) Corresponding to V in FIG. 50Vin (k), corresponding to Vin in fig. 5, represents the voltage value at the present moment; i isL3(K +1) is the current, I, of the predicted inductor L at the future moment when the hybrid semiconductor parallel device is in the conducting stateL4(K +1) is the current of the prediction inductor L at the future time when the hybrid semiconductor parallel device is in the off state;
s32, calculating a cost function C1 in the on state of the switch of the hybrid combiner and a cost function C2 in the off state of the switch of the hybrid combiner;
c1 denotes the value function (I) of the parallel device of the hybrid semiconductor when it is conductedL3Difference between (K +1) and inductor reference current, C2 denotes the cost function (I) when the hybrid semiconductor parallel device is turned offL4Difference of (K +1) and inductance reference current;
s33, judging the sizes of C1 and C2, and if C2 is larger than C1, outputting a rising edge pulse; otherwise, a falling edge pulse is output.
The control principle of the high-performance predictive controller is shown in fig. 5, where GM and GI are driving signals for turning on or off the hybrid semiconductor parallel device, Vref is a reference voltage, and eps is a simulation minimum unit length.
Vin enters a phase-locked loop to obtain a phase angle of Vin; output reference voltage Vref and output voltage sampling value V0Obtaining a voltage error signal by differencing, and sending the voltage error signal to a value- (Vref/(Vin + eps)) obtained by the voltage loop fractional order PI controller for compensation to obtain a reference amplitude of the reference current iref; and finally, multiplying the phase angle result (sine signal sin ω t) of Vin on the left side and the reference amplitude result of the inductive reference current iref on the right side by a multiplier to obtain the value of the inductive reference current iref.
At the same time, inductor reference currents iref and iL (i.e., I) are input into the current loop fractional order predictive controllerL3*(K+1)、IL4(K +1)), comparing C1 and C2, obtaining the driving signal by logic control based on the principle of current equivalence: when C1<At C2, the mixed semiconductor parallel device is turned on when the voltage is C1>At C2, the hybrid semiconductor parallel device is turned off. Therefore, after the nth switching period is finished, the actual inductor current signal can accurately track the reference current signal.
By adopting a self-adaptive maximum power control strategy and a high-performance prediction control method, the tidal power generation device can meet the requirements of high performance and high stability of power supply in the process of power generation on islands, coasts or seas.
Various other modifications and changes may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such modifications and changes should fall within the scope of the claims of the present invention.

Claims (10)

1. A tidal energy control system is characterized by comprising a tidal energy power generation device, a hardware circuit topology and a control module, wherein the hardware circuit topology comprises an uncontrolled rectifying circuit and a Boost converter circuit, and the Boost converter circuit is connected with a hybrid semiconductor parallel device in parallel; the control module comprises a variable step length frequency self-adaptive filtering controller, a maximum power tracking controller and a high-performance prediction controller;
the tidal power generation device is connected with the input end of the uncontrolled rectifying circuit, the output end of the uncontrolled rectifying circuit is connected with the input end of the Boost converter circuit, the output end of the Boost converter circuit is connected with the input end of the variable step frequency self-adaptive filtering controller, the output end of the variable step frequency self-adaptive filtering controller is connected with the input end of the maximum power tracking controller, the output end of the maximum power tracking controller is connected with the input end of the high-performance prediction controller, and the output end of the high-performance prediction controller is connected with the hybrid semiconductor parallel device;
the uncontrolled rectifying circuit is used for converting alternating voltage into direct voltage, the control module enables output voltage and current of the Boost converter circuit to be relatively stable by adjusting connection or disconnection of the hybrid semiconductor parallel device, the variable step frequency self-adaptive filtering controller and the maximum power tracking controller are used for reducing fluctuation of output power of the tidal power generation device, and the high-performance prediction controller is used for improving power factor output by the tidal power generation device.
2. The tidal energy control system of claim 1 wherein the tidal power plant comprises a horizontal axis hydraulic turbine and a permanent magnet generator, the horizontal axis hydraulic turbine being connected to the permanent magnet generator by a rotating shaft.
3. The tidal energy control system of claim 1 wherein the uncontrolled rectifying circuit is a three-phase uncontrolled rectifying circuit, the Boost converter circuit is a two-level Boost converter circuit, and the hybrid semiconductor parallel device is an IGBT/MOSFET hybrid device.
4. A method for the variable step frequency adaptive filtering control of a variable step frequency adaptive filtering controller, wherein the variable step frequency adaptive filtering controller is the variable step frequency adaptive filtering controller in the tidal energy control system according to claim 1, and is characterized in that the frequency of an input digital filter in the variable step frequency adaptive filtering controller is adjusted according to the gradient change of the output power of a Boost converter circuit to the input current frequency of the Boost converter circuit, and a small step is adopted when the gradient is increased; otherwise, large step length is adopted, and the self-carrying interference frequency of the tidal electric energy is filtered; and filtering low-order harmonic waves of the output current of the Boost converter circuit.
5. The method of claim 4, wherein the digital filter is a first order digital filter, the input of the first order digital filter is composed of a current/voltage signal and a cut-off frequency signal, and the output is a filtered signal with a transfer function of
Figure FDA0003593417230000021
6. The method for controlling variable-step frequency adaptive filtering according to claim 4, comprising the steps of:
s01, an initial program is started to detect the voltage Ut and the current It of the output side of the Boost converter and set the initial frequency to be 0.07HZ, and the power Pt of the output side is calculated;
s02, calculating an output-side power from the expression Pt ═ Ut It, an increment Δ Pt ═ Pt (k) -Pt (k-1) of the output power Pt (k-1) at the previous time, and an increment Δ ft ═ ft (k) -ft (k-1) of the cutoff frequency ft (k) at the previous time to the duty ratio ft (k-1) at the previous time;
s03, determining whether the increments Δ Pt and Δ ft are in the same direction, that is, determining whether both Δ Pt and Δ ft are greater than 0 or less than 0, if so, making the cutoff frequency ft (k +1) ft (k) + ftstep for the next cycle, and then returning to step S01; otherwise, go to step S04;
s04, determine whether the increments Δ Pt and Δ ft are reversed, if yes, make the cutoff frequency ft (k +1) of the next cycle ft (k) -ftstep, and then return to step S01.
7. A method of maximum power tracking control of a maximum power tracking controller in a tidal energy control system as claimed in claim 1, wherein the gradient change of the duty ratio is controlled according to the input power of the Boost converter circuit, and the I of the inductor current is adjusted by increasing the input voltage signal of the Boost converter circuitLMagnitude, the input voltage signal increases by one step as the gradient increases; otherwise, one step is reduced, and maximum power tracking of the input power of the front end of the Boost converter circuit is achieved.
8. The maximum power tracking control method according to claim 7, wherein the specific steps of performing maximum power tracking control are as follows:
s11, detecting input side voltage V of boost converter by starting initial programinInput current ILOutput side voltage UtAnd the output side current ItCalculating the input side power Pin；
S12, formula Pin＝Uin*ILCalculating the input side power Pin(k) For the input power P at the previous momentinIncrement of (k-1) (. DELTA.P)inDuty ratio D (k) at the time point to duty ratio D at the previous time pointtIncrement of (k-1) (. DELTA.D)t＝Dt(k)-Dt(k-1); calculating the input voltage signal V at that momentin(k) Step length of (2)
Figure FDA0003593417230000031
S13, judging the increment delta PinAnd Δ DtWhether or not in the same direction, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)>Dt(k-1), or Pin(k)<PinSimultaneous D of (k-1)t(k)<Dt(k-1), if yes, the input voltage signal V of the next period is orderedin(k+1)＝Vin(k)+Vin_stepSubsequently, return is made to step S11; otherwise, go to step S14;
s14, judging the increment delta PinWhether or not Δ Dt is reversed, i.e. Pin(k)>PinSimultaneous D of (k-1)t(k)<Dt(k-1), or Pin(k)<PinSimultaneous D of (k-1)t(k)>Dt(k-1), if yes, the input voltage signal V of the next period is orderedin(k+1)＝Vin(k)-Vin_stepSubsequently, it returns to step S11.
9. A high-performance predictive control method of a high-performance predictive controller in a tidal energy control system according to claim 1, wherein a fractional order differential equation reflecting the inductive current in the two-level Boost converter circuit in the two states of the switch of the hybrid parallel device is established and substituted into a cost function to obtain the inductive current predicted value in the corresponding switch state, so that the inductive current signal of the two-level Boost converter circuit can accurately track the reference current signal after the n switching cycles are finished.
10. The method of high performance predictive control according to claim 9, including the steps of:
s31, reading the output voltage signal V0(k)、IL(k)、Vin(k)、IL3*(K+1)、IL4*(K+1)；
S32, calculating a cost function C1 in the on state of the switch of the hybrid combiner and a cost function C2 in the off state of the switch of the hybrid combiner;
s33, judging the sizes of C1 and C2, and if C2 is larger than C1, leading edge pulse is generated; otherwise the falling edge pulse.
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