CN115498936A - Wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint adjustment - Google Patents
Wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint adjustment Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
- H02P9/26—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
- H02P9/30—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/18—Structural association of electric generators with mechanical driving motors, e.g. with turbines
- H02K7/1807—Rotary generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2205/00—Indexing scheme relating to controlling arrangements characterised by the control loops
- H02P2205/01—Current loop, i.e. comparison of the motor current with a current reference
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient
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Abstract
The invention provides a wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint regulation, which comprises a pressure transmitter; a rotational speed and torque meter; a three-phase PWM rectifier; a generator vector controller; an oil pressure open loop adjusting module; an oil pressure closed loop adjusting module; a displacement regulating electrical drive module; an open-close loop mode switch for switching between open-loop regulation and closed-loop regulation of oil pressure and for generating a fractional displacement signal x m To the regulation of the discharge capacityAn electric drive module; the invention can realize the decoupling control of the rotating speed and the system oil pressure under the actual irregular wave sea condition, and really realize the control effect of constant speed and constant pressure; accessible oil pressure open-loop control and two kinds of forms of oil pressure closed-loop control realize that system oil pressure control is stable, and two kinds of forms can be according to the single configuration of user's actual demand or all configurations, and wherein, open-loop control simple structure need not system oil pressure signal feedback, satisfies basic demand, and closed-loop control structure control effect is more.
Description
Technical Field
The invention belongs to the field of wave energy power generation, and particularly relates to a wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint regulation.
Background
Constant-pressure hydraulic PTO (CPHPTO) is a common transmission form in a wave power generation device. The CPHPTO is additionally provided with the high-pressure energy accumulator between the hydraulic cylinder and the motor, so that the fluctuation of the internal oil pressure, flow and the rotating speed of the motor is greatly reduced, and the energy conversion efficiency is improved. A disadvantage of CPHPTO is that it is difficult to achieve rapid adjustment of the PTO force (torque) by changing the motor displacement. CPHPTO is currently widely used in sea snake type devices, wavestar devices, raft type devices, heaving float devices, and various pendulum type devices, such as SEAREV devices, eagle type devices, buoyancy pendulum devices, floating pendulum devices, and resonance type devices.
Although the energy conversion efficiency of the CPHPTO is high and the working point is stable, the nonlinear energy loss in the CPHPTO is still not negligible, and the working point of the system still fluctuates slightly under the complex irregular wave sea state and the limited nominal volume of the high-pressure accumulator. Therefore, it is still necessary to fully examine various possible operating points and to operate the CPHPTO in a high-efficiency stable region by operation control, so as to avoid excessive transmission loss and severe fluctuation of operating parameters.
The document "Integrated Circuit Current of the constant-pressure Power take-off in wave Energy conversion" (Journal article, journal name: international Journal of Electrical Power and Energy Systems, published year: 2019, volume number: 117, article number: 105730) indicates that the operation curve in the CPHPTO comprehensive characteristic curve can be used to guide the efficient and stable operation of CPHPTO. The operating curves include the constant flow line, the force limit line and the constant efficiency line. Wherein the output limiting line passes through the high-efficiency stable regions under different flow rates. The output limiting line comprises two sections, wherein the first section is limited by the designed output (namely rated power of the three-phase permanent magnet synchronous generator), and the second section is limited by the designed rotating speed (namely rated rotating speed of the three-phase permanent magnet synchronous generator) and the designed system oil pressure (namely designed hydraulic motor inlet oil pressure, and because the outlet of the hydraulic motor is connected with a low-pressure oil tank, the outlet oil pressure is far lower than the inlet oil pressure, the designed system oil pressure can also be regarded as the designed hydraulic motor inlet-outlet pressure difference). When the instantaneous output exceeds the design output, the system flow exceeds the design flow, the flow is limited to the design flow through the speed regulating valve, the output is limited to the design output, when the instantaneous output is smaller than the design output, the system operates according to a second section of output limiting line, and the system oil pressure and the system rotating speed are respectively stabilized at the design system oil pressure and the design rotating speed through constant-speed and constant-pressure control.
The invention discloses a comprehensive characteristic curve acquisition method based on a wave power generation hydraulic PTO system (patent number ZL 201710346136.1, granted date: 19.6.2020), further indicates that the rotation speed of an output shaft of a hydraulic motor can be maintained to be the rated rotation speed of a three-phase permanent magnet synchronous generator by adjusting the displacement of the hydraulic motor, and the mechanical torque of a main shaft is adjusted by vector control of the three-phase permanent magnet synchronous generator, so that the pressure difference of an inlet and an outlet of the hydraulic motor is stabilized, and finally constant-speed constant-pressure control is realized. However, the structural design and control flow of the controller of the constant-speed and constant-pressure control strategy are not elaborated in detail in the patent.
At present, scholars propose constant-speed constant-pressure control technologies based on CPHPTO and carry out simulation research. The document, "research on key technologies of buoyancy pendulum type wave energy power generation devices" (doctor's paper, published unit: zhejiang university, published time: 2011) indicates that constant speed and constant voltage of CPHPTO and stability of output power under the action of ideal periodic step wave force can be realized through variable motor displacement control or variable electrical load control, wherein the variable electrical load control has better operation stability on the CPHPTO. The CPHPTO system oil pressure is limited by overflow valve overflow aiming at ideal sinusoidal reciprocating motion and alternating current resistive load of a hydraulic cylinder piston rod, and the stability of the rotating speed and the output power is realized based on motor displacement PID Control in the literature < Operation characteristics and methods of the hydraulic power take-off system > (journal article, journal name: transactions of the Institute of Measurement and Control, published year: 2020, volume number: 43, term number: 5, article number: 014233122093435).
The constant-speed constant-pressure control technology has the following two defects:
1) The input of CPHPTO is excessively simplified in the research process, so that the simulation result is ideal, and the difference from the actual situation is large, therefore, the constant-speed constant-voltage control technology has low actual operability and cannot be used for guiding the actual operation process. The literature, namely the research on key technology of the buoyancy pendulum type wave energy power generation device, simplifies input wave force into periodic step force, and the literature, namely the literature, namely the Operation characteristics and the methods of the hydro power take-offset, simplifies input displacement of a hydraulic cylinder into sinusoidal reciprocating motion, and both the literature and the literature cannot effectively research input conditions under actual irregular wave sea conditions.
2) The oil pressure and the rotating speed of the system cannot be synchronously constant. In the literature, "research on key technologies of buoyancy pendulum wave power generation devices" only uses single variable motor displacement control or variable electrical load control, and the single control can only realize the stability of a single working condition parameter (namely, system oil pressure or rotating speed), while the other working condition parameter tends to fluctuate under actual irregular wave sea conditions. In contrast, the literature, "Operation characteristics and methods of the hydraulic power stick-off system" only limits the upper limit of the system oil pressure of CPHPTO through an overflow valve, and does not implement effective feedback control on the system oil pressure, so that only the constant rotation speed can be realized, the pressure inevitably fluctuates in real time under the actual irregular wave sea condition, and the system oil pressure is stabilized at the overflow pressure only when the overflow occurs under the sea condition.
The inventor finds that the fundamental problem of the prior art is that the system oil pressure can fluctuate violently without considering actual irregular wave sea conditions and limited accumulator volume when the CPHPTO constant-speed constant-pressure control technology is researched, for example, when the sea conditions are small and the system oil pressure is lower than the charging pressure of the accumulator, the accumulator cannot work normally, and the system oil pressure fluctuates violently; when the sea condition is large and the oil pressure of the system is far higher than the design pressure, the pressure stabilizing capacity of the energy accumulator is reduced, and the amplitude of the oil pressure of the system is increased under the same volume of liquid charging and discharging. The CPHPTO has unique pressure-flow-rotating speed coupling characteristics, so that the fluctuation of the system oil pressure and the fluctuation of the rotating speed are related but not mutually determined, for example, when the system oil pressure is constant through control, the fluctuation of the hydraulic power and the flow is generated due to the fluctuation of the input power under irregular wave sea conditions and the limited action of an energy accumulator, and the flow fluctuation is transmitted to the output shaft of the hydraulic motor and the three-phase permanent magnet synchronous generator shaft synchronously rotating with the output shaft of the hydraulic motor through a relational expression (without efficiency loss) of flow = rotating speed and hydraulic motor displacement, so that the rotating speed cannot be constant; when the rotation speed is controlled to be constant, but the input power fluctuates under irregular wave sea conditions and the limited action of the accumulator causes that the load torque of the hydraulic motor must synchronously fluctuate to maintain the input and output power balance, the system oil pressure also fluctuates and cannot be constant according to a relational expression of system oil pressure = hydraulic motor load torque × 2 × pi ÷ hydraulic motor displacement (without considering efficiency loss). Therefore, it is not practical to achieve the constancy of the system oil pressure and the rotational speed at the same time by a single control.
Disclosure of Invention
The invention aims to provide a wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint regulation, and solves the problem that the existing CPHPTO constant-speed constant-pressure control technology cannot realize the synchronous constant of the oil pressure and the rotating speed of the system under the actual irregular wave sea condition.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides a wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint regulation, which comprises
The pressure transmitter is used for acquiring a system oil pressure signal p of the main oil way and transmitting the oil pressure signal p to the oil pressure closed-loop adjusting module;
a rotational speed torquemeter for measuring the torque signal M of the input shaft of the three-phase permanent magnet synchronous generator g And a rotation speed signal n, and a signal M g N is sent to the oil pressure open-loop regulating module, and a signal n is sent to the oil pressure closed-loop regulating module;
the three-phase PWM rectifier controls the electromagnetic torque of the three-phase permanent magnet synchronous generator and indirectly adjusts the rotating speed n;
the generator vector controller collects three-phase current signals i at the outlet of the three-phase permanent magnet synchronous generator a ，i b ，i c And outputs SVPWM signal to three-phase PWM rectifier, and receives rotation speed signal n and set rotation speed n r ；
An oil pressure open loop regulating module for obtaining a set oil pressure p r And a set rotation speed n r And computing a fractional displacement signal x m ；
Oil pressure closed loop regulating module for obtaining set oil pressure p r And a set rotation speed n r And computing a fractional displacement signal x m ；
Displacement regulating electric drive module based on fractional displacement signal x m The control current is linearly adjusted, and the control current is transmitted to an electromagnetic valve of the variable displacement hydraulic motor to control the displacement of the motor;
an open-close loop mode switch for switching between open-loop regulation and closed-loop regulation of oil pressure and for generating a fractional displacement signal x m To a displacement regulating electric drive module;
the invention is further provided that the oil pressure open loop adjusting module comprises a saturation link, a condition judging link and a zero order keeping link, and the oil pressure open loop adjusting module calculates a fractional discharge capacity intermediate value x mm The formula is as follows:
fractional displacement median x mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link m0 And is sent toA condition judging step for judging whether the relative rotation speed difference delta is less than the set rotation speed difference delta 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output the given fractional displacement x m1 The output result of the condition judging link is subjected to discrete processing by a zero-order keeping link and then is used as a fractional displacement signal x m And (6) outputting.
The invention further provides that the oil pressure closed loop regulation module comprises a discrete PI regulator, a saturation link, a condition judgment link and a zero order keeping link, and a system oil pressure signal p and a set oil pressure p r The deviation amount of the integral displacement intermediate value x is calculated by a discrete PI regulator mm The formula is as follows:
in the formula, K pp Is a proportionality coefficient, K ip As an integral coefficient, T sp2 Sampling time fractional displacement median x for discrete PI regulators mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link m0 And sending the relative rotation speed difference delta to a condition judging link, and judging whether the relative rotation speed difference delta is smaller than the set rotation speed difference delta or not by the condition judging link 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output the given fractional displacement x m1 The output result of the condition judging link is treated discretely by the zero-order keeping link and then is used as a fractional displacement signal x m And (6) outputting.
The invention further provides that the calculation formula of the relative rotation speed difference delta is as follows:
the invention further sets that the upper limit and the lower limit of the saturation link are respectively 1 and the minimum fractional displacement of the hydraulic motor.
The invention is further provided that the set rotational speed difference Δ is 0 The sum of the relative value of the steady-state error and the relative value of the disturbance deviation which is greater than the rotating speed n is needed.
According to a further aspect of the invention, the given fractional displacement x m1 Is any value between the minimum fractional displacement of the hydraulic motor and 1.
The invention further sets that the sampling time of the zero-order holding link is required to be longer than the time length of the adjusting process of the displacement of the hydraulic motor from the minimum value to the maximum value or from the maximum value to the minimum value.
The invention further sets that the sampling time of the discrete PI regulator is less than or equal to the sampling time of the zero-order holding link, and the discrete PI regulator is regulated according to the requirement of calculation precision.
The invention further provides that the generator vector controller comprises a rotating speed ring PI regulator, a current ring PI regulator, an SVPWM algorithm module, a Clark conversion module, a Park conversion module and an inverse Park conversion module, wherein the rotating speed ring PI regulator is used for regulating the rotating speed according to a rotating speed signal n and a set rotating speed n r Calculating a given q-axis current signal
Sending to a current loop PI regulator, and carrying out Clark conversion and Park conversion on the measured three-phase current value i a i b i c Conversion to i under two-phase stationary coordinate system alpha-beta α i β And further converted into i under a synchronous rotating coordinate system d-q d i q Sent to a current loop PI regulator which sets a given d-axis current signal
And according to i d i q And
calculating a given voltage signal
Then, the inverse Park transform will
Conversion to alpha-beta coordinate
SVPWMAlgorithm according to
And outputting a PWM signal to control the three-phase PWM rectifier.
The invention has the beneficial effects that: 1. the decoupling control of the rotating speed and the system oil pressure under the actual irregular wave sea condition can be realized, and the control effect of constant speed and constant pressure is really realized.
2. Accessible oil pressure open-loop control and two kinds of forms of oil pressure closed-loop control realize that system oil pressure control is stable, and two kinds of forms can be according to the single configuration of user's actual demand or all configurations, and wherein, open-loop control simple structure need not system oil pressure signal feedback, satisfies basic demand, and closed-loop control structure control effect is more.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
FIG. 1 is a mechanical structure diagram of a buoyancy pendulum type wave energy power generation device based on a constant pressure type hydraulic PTO;
FIG. 2 is a structural diagram of a constant-speed constant-pressure control structure of a wave energy power generation hydraulic PTO based on two-parameter joint debugging;
FIG. 3 is a block diagram of an oil pressure open loop adjustment module;
FIG. 4 is a block diagram of a closed loop oil pressure regulation module;
FIG. 5 is a block diagram of a generator vector controller architecture;
FIG. 6 is a graph showing the variation of a rotation speed signal under constant speed and constant pressure control;
FIG. 7 is a graph showing the variation of the oil pressure signal of the system under constant speed and constant pressure control;
fig. 8 is a plot of the actual operation of a constant pressure hydraulic PTO with generator vector control and uncontrolled motor displacement;
fig. 9 is a constant-pressure type hydraulic PTO actual operation curve under constant-speed constant-pressure control and open-loop regulation of oil pressure;
fig. 10 is a constant-pressure type hydraulic PTO actual operation curve under constant-speed constant-pressure control and oil pressure closed-loop regulation; reference numerals: 1-a buoyancy pendulum body; 2-a guide rod group; 3-a rack; 4-a gear; 5-a main shaft; 6-1-a first hydraulic cylinder; 6-2-hydraulic cylinder II; 7-1-a one-way valve I; 7-2-one-way valve II; 7-3-a one-way valve III; 7-4-check valve four; 8-a high pressure accumulator; 9-a speed regulating valve; 10-variable displacement hydraulic motor; 11-a three-phase permanent magnet synchronous generator; 12-an overflow valve; 13-a low pressure tank; 14-a pressure transmitter; 15-rotational speed torquemeter; 16-a three-phase PWM rectifier; 17-a direct current bus; 18-displacement regulating electrical drive module; 19-switching ring mode change-over switch; 20-oil pressure open loop adjusting module; 21-oil pressure closed loop regulating module; 22-generator vector controller; 23-main oil way; 24-1-saturated ring; 24-2-saturated ring; 25-1-condition judgment link; 25-2-judging the condition; 26-1-zero order keeper; 26-2-zero order hold link; 27-discrete PI regulator; 28-rotating speed ring PI regulator; 29-current loop PI regulator.
Detailed Description
Embodiments of the present application will be described in detail with reference to the drawings and examples, so that how to implement technical means to solve technical problems and achieve technical effects of the present application can be fully understood and implemented.
The inventor finds that the CPHPTO irregular wave simulation research firstly utilizes the generator vector to control the stable rotating speed, and starts to implement the motor displacement control to stabilize the oil pressure when the rotating speed deviation is less than a certain threshold value, so that the synchronization and constancy of the rotating speed and the system oil pressure under the actual irregular wave sea condition can be realized, and the real constant speed and constant pressure control effect can be achieved.
The invention does not consider the constant-speed constant-pressure control strategy of stabilizing oil pressure by generator vector control and stabilizing rotating speed by motor displacement control, which is described in the invention patent of 'comprehensive characteristic curve acquisition method based on wave power generation hydraulic PTO system', because: the physical limitation of the maximum and minimum displacement of the motor enables the rotating speed stability of the motor displacement control to be limited under the condition that the flow is changed in a large range, and the indirect control of the oil pressure through vector control easily causes the motor to reversely pump oil.
Therefore, the following technical scheme is proposed:
the invention relates to a wave energy power generation hydraulic PTO constant-speed constant-pressure control method based on double-parameter joint regulation, which aims at a wave energy power generation device adopting a constant-pressure hydraulic PTO structure.
The embodiment examines a buoyancy pendulum type wave energy power generation device based on a constant pressure type hydraulic PTO shown in figure 1, and the mechanical structure comprises: a buoyancy pendulum body 1; a guide rod group 2; a rack 3; a gear 4; a main shaft 5 and a constant pressure hydraulic PTO. The constant pressure hydraulic PTO includes: 6-1 of a hydraulic cylinder; a second hydraulic cylinder 6-2; 7-1 of a one-way valve; a second check valve 7-2; 7-3 of a one-way valve; 7-4 parts of a check valve IV; a high-pressure accumulator 8; a speed regulating valve 9; a variable displacement hydraulic motor 10; a three-phase permanent magnet synchronous generator 11; an overflow valve 12; a low-pressure oil tank 13; and a main oil passage 23. The buoyancy pendulum body 1 is mounted on the main shaft 5 and can rotate relative to the main shaft. The cylinder body of the first hydraulic cylinder 6-1, the cylinder body of the second hydraulic cylinder 6-2, the one-way valve I7-1, the one-way valve II 7-2, the one-way valve III 7-3, the one-way valve IV 7-4, the high-pressure energy accumulator 8, the speed regulating valve 9, the variable displacement hydraulic motor 10, the three-phase permanent magnet synchronous generator 11, the overflow valve 12, the low-pressure oil tank 13, the pressure transmitter 14, the rotating speed torquemeter 15 and the main oil path 23 are all fixed on the inner side wall of the buoyancy pendulum body 1. The gear 4 is fixed on the main shaft 5 and meshed with the rack 3. A ribbed plate is welded in the middle of the back of the rack 3, and two sides of the ribbed plate are fixedly connected with a piston rod of the first hydraulic cylinder 6-1 and a piston rod of the second hydraulic cylinder 6-2 respectively. The guide rod group 2 is divided into an upper guide rod and a lower guide rod, and two ends of the guide rods are fixedly connected with the cylinder body of the first hydraulic cylinder 6-1 and the cylinder body of the second hydraulic cylinder 6-2 respectively. The rib plate of the rack 3 is provided with a through hole, and the guide rod group 2 passes through the through hole and forms a moving pair with the rack 3 through a linear bearing. An oil port of the first hydraulic cylinder 6-1 is connected with an oil inlet of the first check valve 7-1 and an oil outlet of the third check valve 7-3, an oil port of the second hydraulic cylinder 6-2 is connected with an oil inlet of the second check valve 7-2 and an oil outlet of the fourth check valve 7-4, an oil outlet of the first check valve 7-1 and an oil outlet of the second check valve 7-2 are connected with an oil inlet of the main oil way 23, and an oil inlet of the third check valve 7-3 and an oil inlet of the fourth check valve 7-4 are connected with an oil outlet of the main oil way 23. The oil inlet of the main oil path 23 is also divided into one path of oil path to be connected to the oil inlet of the overflow valve 12, and the oil outlet of the overflow valve 12 is connected to the low-pressure oil tank 13. The oil outlet of the main oil path 23 is also divided into one oil path to be connected to the low-pressure oil tank 13. A high-pressure accumulator 8, a speed regulating valve 9, a pressure transmitter 14 and a variable displacement hydraulic motor 10 are sequentially arranged between an oil inlet and an oil outlet of the main oil way 23. The output shaft of the variable displacement hydraulic motor 10 is connected with the input shaft of the rotating speed and torque instrument 15, and the output shaft of the rotating speed and torque instrument 15 is connected with the input shaft of the three-phase permanent magnet synchronous generator 11 through couplings.
The working principle of the buoyancy pendulum wave power generation device based on the constant pressure type hydraulic PTO is as follows: the buoyancy pendulum body 1 is completely immersed in seawater, stands on the main shaft 5 under the action of buoyancy moment, and when incident waves act on the front surface of the buoyancy pendulum body 1, the buoyancy pendulum body 1 swings around the main shaft 5. The swinging of the buoyancy pendulum body 1 relative to the main shaft 5 is converted into the translation of the rack 3 relative to the guide rod group 2 through the meshed gear 4 and the rack 3. The rack 3 further pushes the piston rods of the first hydraulic cylinder 6-1 and the second hydraulic cylinder 6-2 to move relative to the cylinder body through the back rib plate, so that the oil cavity expands to absorb oil or is compressed to generate high-pressure oil. When the rib plate 3 of the rack pushes a piston rod of the hydraulic cylinder II 6-2 to compress an oil cavity of the hydraulic cylinder II 6-2, the generated high-pressure oil enters an oil inlet of the main oil way 23 through the check valve I7-1, sequentially passes through the high-pressure energy accumulator 8, the speed regulating valve 9, the pressure transmitter 14 and the variable displacement hydraulic motor 10, then reaches an oil outlet of the main oil way 23, and enters the oil cavity of the hydraulic cylinder I6-1 through the check valve IV 7-4. Similarly, when the rib plate 3 of the rack pushes the piston rod of the hydraulic cylinder I6-1 to compress the oil cavity of the hydraulic cylinder I6-1, the generated high-pressure oil enters the oil inlet of the main oil path 23 through the second one-way valve 7-2, sequentially passes through the high-pressure energy accumulator 8, the speed regulating valve 9, the pressure transmitter 14 and the variable displacement hydraulic motor 10, then reaches the oil outlet of the main oil path 23, and enters the oil cavity of the hydraulic cylinder II 6-2 through the third one-way valve 7-3. The 4 one-way valves play a role in rectification and convert the two-way flow of high-pressure oil into one-way flow on the main oil way 23. The relief valve 12 is used to prevent the constant pressure hydraulic PTO from being overpressurized, and opens the relief when the inlet oil pressure of the main oil passage 23 reaches the upper limit of the working oil pressure. The high-pressure accumulator 8 is used for stabilizing the oil pressure of an oil inlet of the main oil way 23, and further stabilizing the flow of the main oil way 23. The speed regulating valve 9 is used for flow regulation of the main oil way 23 and participates in power generation power control, and meanwhile when the flow of the main oil way 23 reaches the upper flow limit, the flow can be limited through the speed regulating valve 9 in order to avoid over-speed of the rotating speed of the three-phase permanent magnet synchronous generator 11. The variable displacement hydraulic motor 10 is used for converting hydraulic energy into rotary mechanical energy, and the three-phase permanent magnet synchronous generator 11 is used for converting the rotary mechanical energy into electric energy to be output. The low-pressure oil tank 13 is used for stabilizing the oil pressure of an oil outlet of the main oil path 23, supplementing system leakage and eliminating short-time negative pressure.
The constant-speed and constant-pressure control structure of the constant-pressure hydraulic PTO is shown in fig. 2, and comprises a pressure transmitter 14 and a rotational speed and torque meter 15 for signal acquisition, a three-phase PWM rectifier 16, a dc bus 17 and a generator vector controller 22 for generator vector control, a displacement adjustment electric drive module 18 for motor displacement control, an open-close loop mode switch 19, an oil pressure open-loop adjustment module 20 and an oil pressure closed-loop adjustment module 21. A pressure transmitter 14 is arranged between an oil outlet of the speed regulating valve 9 and an oil inlet of the variable displacement hydraulic motor 10, a system oil pressure signal p of a main oil path 23 is collected to an oil pressure closed loop adjusting module 21, a rotating speed torque instrument 15 is arranged between an output shaft of the variable displacement hydraulic motor 10 and an input shaft of the three-phase permanent magnet synchronous generator 11, and a torque signal M of the input shaft of the three-phase permanent magnet synchronous generator 11 is measured g And a rotating speed signal n is sent to the oil pressure open loop adjusting module 20, and the rotating speed signal n is divided into one path to the generator vector controller 22. Set oil pressure p r And respectively sent to an oil pressure open-loop regulating module 20 and an oil pressure closed-loop regulating module 21 in two paths. Set rotational speed n r And the oil pressure is sent to an oil pressure open-loop regulating module 20, an oil pressure closed-loop regulating module 21 and a generator vector controller 22 in three ways. The oil pressure open-loop regulating module 20 and the oil pressure closed-loop regulating module 21 calculate a fraction displacement signal x m Then, the signal is sent to the displacement adjusting electric driving module 18 through the switching ring mode switch 19, and the displacement adjusting electric driving module 18 is used for outputting a fractional displacement signal x m And the control current is linearly adjusted and sent to the solenoid valve of the variable displacement hydraulic motor 10 to control the displacement of the motor, and the open-close loop mode change-over switch 19 is used for switching between oil pressure open loop adjustment and oil pressure closed loop adjustment according to the requirements of users. The generator vector controller 22 collects three-phase current signals i at the outlet of the three-phase permanent magnet synchronous generator 11 a i b i c And outputs an SVPWM signal to the three-phase PWM rectifier 16, and the three-phase PWM rectifier 16 controls the electromagnetic torque of the three-phase permanent magnet synchronous generator 11, thereby indirectly realizing the adjustment of the rotation speed n.
The oil pressure open loop regulating module 20The internal structure is shown in fig. 3. Calculating a fractional displacement median x according to equation (1) mm ：
In the formula (1), D m Indicating the maximum displacement of the hydraulic motor provided by the equipment manufacturer,
indicating the hydraulic motor set mechanical efficiency. Fractional displacement median x mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link 24-1 m0 And sent to the condition judging link 25-1. The condition judging step 25-1 judges whether the relative rotation speed difference delta is smaller than the set rotation speed difference delta 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output the given fractional displacement x m1 . The output result of the 1# condition judgment link 25-1 is subjected to discrete processing by the zero order holding link 26-1 to be used as a fractional displacement signal x m And (6) outputting.
The internal structure of the oil pressure closed-loop control module 21 is shown in fig. 4. System oil pressure signal p and set oil pressure p r Is calculated by the discrete PI regulator 27 as the fractional displacement median x mm The formula is as follows:
in the formula, K pp Is a proportionality coefficient, K ip As an integral coefficient, T sp2 The sampling time is discrete PI regulator. Fractional displacement median x mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link 24-2 m0 And sent to the 2# condition judgment link 25-2. The condition judging step 25-2 judges whether the relative rotation speed difference Delta is smaller than the set rotation speed difference Delta 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output a given fractional displacement x m1 . The output result of the 2# condition judgment link 25-2 is subjected to discrete processing by the zero order keeping link 26-2 and then is used as a fractional displacement signal x m And (6) outputting.
The hydraulic motor sets the mechanical effectRate of change
In relation to the energy characteristics of the hydraulic motor, it is generally desirable to be 0.9 or more.
The upper limit and the lower limit of the saturation link 24-1 and the saturation link 24-2 are respectively 1 and the minimum fractional displacement of the hydraulic motor.
The relative rotational speed difference Δ is calculated according to equation (2):
the set rotational speed difference Δ 0 The sum of the relative value of the steady state error and the relative value of the disturbance deviation which are larger than the rotating speed n is needed to avoid that the output values of the 1# condition judgment link 25-1 and the 2# condition judgment link 25-2 are in x under the condition that the rotating speed n is disturbed m0 And x m1 The switching between the constant speed and the constant pressure affects the stability of the constant speed and the constant pressure control, and generally can be 0.05.
The given fractional displacement x m1 And may be any value between the minimum fractional displacement of the hydraulic motor and 1 provided by the equipment manufacturer.
The sampling time of the zero-order holding link 26-1 and the zero-order holding link 26-2 is required to be longer than the adjusting process time of the displacement of the hydraulic motor from the minimum value to the maximum value or from the maximum value to the minimum value, generally longer than 0.05s, so as to avoid the situation that the actual displacement adjusting speed cannot keep up with the fractional displacement signal x m The situation of varying speed.
The sampling time of the discrete PI regulator 27 is generally less than or equal to the sampling time of the zero-order holding element 26-1 and the zero-order holding element 26-2, and can be adjusted according to the requirement of calculation accuracy.
The internal structure of the generator vector controller is shown in fig. 5, and comprises a rotating speed loop PI regulator 28, a current loop PI regulator 29, an SVPWM algorithm, clark conversion, park conversion and inverse Park conversion. First, the speed loop PI regulator 28 adjusts the speed according to the speed signal n and the set speed n r Calculating a given q-axis current signal
To a current loop PI regulator 29. Secondly, clark conversion and Park conversion are carried out to measure three-phase current values i a i b i c Conversion to i under two-phase stationary coordinate system alpha-beta α i β And further converted into i under a synchronous rotating coordinate system d-q d i q To a current loop PI regulator 29. Again, current loop PI regulator 29 sets the given d-axis current signal
And according to i d i q And
calculating a given voltage signal
Then, the inverse Park transform will
Conversion to alpha-beta coordinate
Finally, SVPWM algorithm is based on
The output PWM signal controls a three-phase PWM rectifier 16.
The wave energy power generation hydraulic PTO constant-speed constant-pressure control method based on the double-parameter joint regulation has good rotating speed stability and pressure stability effects. The control effect is explained by the comparison of irregular wave sea state simulation, and the key parameter setting is shown in table 1.
TABLE 1 Key parameter settings Table
The simulation results are shown in fig. 6 to 10. Wherein, FIG. 6 and FIG. 7 are respectivelyThe change curve of the rotating speed signal and the change curve of the system oil pressure signal under constant speed and constant pressure control are shown. As can be seen from the graphs in FIGS. 6 and 7, the constant-speed constant-pressure control of the wave power generation hydraulic PTO based on the two-parameter joint regulation can stabilize the rotating speed signal at the set rotating speed n r The system oil pressure signal is stabilized at the set oil pressure p r And the performance of the oil pressure closed-loop adjusting module is better than that of the oil pressure open-loop adjusting module, the overshoot of the oil pressure signal transition process of the system is small, and steady-state error fluctuation is avoided. Fig. 8 to 10 are respectively constant pressure type hydraulic PTO actual operation curves of generator vector control with no control of motor displacement, constant speed and constant pressure control with open loop regulation of oil pressure, constant speed and constant pressure control with closed loop regulation of oil pressure, plotted on a flow q-output N plane. It should be noted that the rotation speed signal n of the actual operation curve in fig. 8 to 10 is substantially stabilized at the set rotation speed n r Nearby, and the error is less than +/-1%. Fig. 8 to 10 show the maximum flow rate line (i.e., the horizontal straight line q = q) in addition to the actual operating curve of the constant pressure type hydraulic PTO max ) Line of minimum flow (i.e. horizontal straight line q = q) min ) Maximum displacement line (i.e. diagonal line D = D) m ) Line of minimum displacement (i.e. diagonal line D = 0.3D) m ) The charging pressure line of the high-pressure accumulator (i.e. inclined straight line p =0.8 p) r ) And the force limit line (i.e. straight line p = p) r And straight line N = N r The formed broken line), wherein, the area enclosed by the charging pressure line and the maximum displacement line of the high-pressure accumulator is a stable operation area, and the area passed by the output limiting line is a constant-pressure type hydraulic PTO high-efficiency stable area, so the actual operation curve of the constant-pressure type hydraulic PTO in an ideal state must operate along the output limiting line. Under the condition of vector control of a generator and uncontrolled motor displacement, the actual operation curve of the constant pressure type hydraulic PTO and the output limiting line are not overlapped at all, the time period of operation in an unstable operation area is long, and the economical efficiency and the safety of the operation of the constant pressure type hydraulic PTO are difficult to guarantee. Under the conditions of constant-speed constant-pressure control, oil pressure open-loop regulation, constant-speed constant-pressure control and oil pressure closed-loop regulation, the actual operation curve of the constant-pressure hydraulic PTO can move along the output limiting line, the constant-pressure hydraulic PTO operates in a stable operation area in most of time, and the economical efficiency and the safety of the operation of the constant-pressure hydraulic PTO can be guaranteed. The constant-speed constant-pressure control and oil pressure closed-loop regulation have better regulation effect and higher contact ratio with the output limiting line.
As used in the specification and in the claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, that a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect.
It is noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of additional like elements in a commodity or system comprising the element.
The foregoing description shows and describes several preferred embodiments of the invention, but as aforementioned, it is to be understood that the invention is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides a wave energy electricity generation hydraulic pressure PTO constant speed constant voltage control system based on two parameter allies oneself with transfers which characterized in that: comprises that
The pressure transmitter is used for acquiring a system oil pressure signal p of the main oil way and transmitting the oil pressure signal p to the oil pressure closed-loop adjusting module;
a rotational speed torquemeter for measuring the torque signal M of the input shaft of the three-phase permanent magnet synchronous generator g And a rotation speed signal n, and a signal M g N is sent to an oil pressure open-loop regulating module, and a signal n is sent to the oil pressure closed-loop regulating module and a generator vector controller;
the three-phase PWM rectifier controls the electromagnetic torque of the three-phase permanent magnet synchronous generator and indirectly adjusts the rotating speed n;
the generator vector controller collects three-phase current signals i at the outlet of the three-phase permanent magnet synchronous generator a ，i b ，i c And outputs SVPWM signal to three-phase PWM rectifier, and receives rotation speed signal n and set rotation speed n r ；
An oil pressure open-loop adjusting module for obtaining a set oil pressure p r Setting a rotational speed n r A rotational speed signal n and a torque signal M g Given fractional displacement x m1 And computes a fractional displacement signal x m ；
Oil pressure closed loop regulating module for obtaining set oil pressure p r Setting a rotational speed n r A rotation speed signal n, an oil pressure signal p and a given fractional displacement x m1 And computes a fractional displacement signal x m ；
Displacement regulating electrical drive module based on fractional displacement signal x m The control current is linearly adjusted, and the control current is transmitted to an electromagnetic valve of the variable displacement hydraulic motor to control the displacement of the motor;
an open-close loop mode switch for switching between open-loop regulation and closed-loop regulation of oil pressure,
and will divide the displacement signal x m To the displacement regulating electric drive module.
2. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the two-parameter joint regulation is characterized in that the oil pressure open-loop regulation module comprises a saturation link, a condition judgment link and a zero-order maintenance link,the oil pressure open loop adjusting module calculates a fractional displacement intermediate value x mm The formula is as follows:
fractional displacement median x mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link m0 And sending the relative rotation speed difference delta to a condition judging link, and judging whether the relative rotation speed difference delta is smaller than the set rotation speed difference delta or not by the condition judging link 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output the given fractional displacement x m1 The output result of the condition judging link is treated discretely by the zero-order keeping link and then is used as a fractional displacement signal x m And (6) outputting.
3. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the double-parameter joint regulation as claimed in claim 1, wherein the oil pressure closed-loop regulation module comprises a discrete PI regulator, a saturation link, a condition judgment link and a zero-order maintenance link, a system oil pressure signal p and a set oil pressure p r The deviation amount of the integral displacement intermediate value x is calculated by a discrete PI regulator mm The formula is as follows:
in the formula, K pp Is a proportionality coefficient, K ip As an integral coefficient, T sp2 Fractional displacement intermediate value x for discrete PI regulator sample time mm Obtaining a fractional displacement calculation value x after the amplitude limiting of a saturation link m0 And sending the relative rotation speed difference delta to a condition judging link, and judging whether the relative rotation speed difference delta is smaller than the set rotation speed difference delta or not by the condition judging link 0 If delta is less than or equal to delta 0 Then x is output m0 Otherwise, output the given fractional displacement x m1 The output result of the condition judging link is subjected to discrete processing by a zero-order keeping link and then is used as a fractional displacement signal x m And (6) outputting.
4. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the two-parameter joint regulation as claimed in claim 2 or 3, characterized in that the calculation formula of the relative rotation speed difference delta is as follows:
5. the wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the double-parameter joint debugging as claimed in claim 2 or 3, wherein the upper limit and the lower limit of the saturation link are respectively 1 and the minimum fractional displacement of the hydraulic motor.
6. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on double-parameter joint regulation as claimed in claim 2 or 3, characterized in that the set rotation speed difference delta 0 The sum of the relative value of the steady-state error and the relative value of the disturbance deviation which is greater than the rotating speed n is needed.
7. A wave energy generation hydraulic PTO constant speed and constant pressure control system based on two-parameter joint debugging according to claim 2 or 3, characterized in that the given fractional displacement x is m1 Is any value between the minimum fractional displacement of the hydraulic motor and 1.
8. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the double-parameter joint debugging is characterized in that the sampling time of the zero-order holding link is longer than the adjusting process time of the displacement of the hydraulic motor from the minimum value to the maximum value or from the maximum value to the minimum value.
9. The wave energy power generation hydraulic PTO constant-speed constant-pressure control system based on the double-parameter joint debugging of claim 3, wherein the sampling time of the discrete PI regulator is less than or equal to that of a zero-order holding link, and the sampling time is adjusted according to the requirement of calculation accuracy.
10. Wave energy power generation liquid based on two-parameter joint modulation according to claim 1The constant-speed constant-pressure control system of the pressure PTO is characterized in that the generator vector controller comprises a rotating speed loop PI regulator, a current loop PI regulator, an SVPWM algorithm module, a Clark conversion module, a Park conversion module and an inverse Park conversion module, and the rotating speed loop PI regulator is used for controlling the rotating speed according to a rotating speed signal n and a set rotating speed n r Calculating a given q-axis current signal
Sending to a current loop PI regulator, and carrying out Clark conversion and Park conversion on the measured three-phase current value i a i b i c Conversion to i in a two-phase stationary coordinate system alpha-beta α i β And further converted into i under a synchronous rotating coordinate system d-q d i q Sent to a current loop PI regulator which sets a given d-axis current signal
And according to i d i q And
calculating a given voltage signal
Then, the inverse Park transform will
Conversion to alpha-beta coordinate
SVPWM algorithm based on
And outputting a PWM signal to control the three-phase PWM rectifier.
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