CN106777596B - Microgrid semi-physical simulation system and wind driven generator closed-loop control method - Google Patents
Microgrid semi-physical simulation system and wind driven generator closed-loop control method Download PDFInfo
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Abstract
The embodiment of the invention discloses a microgrid semi-physical simulation system and a wind driven generator closed-loop control method, which comprise an input parameter control module, a wind driven generator simulation module and a grid-connected module, wherein the input parameter control module is used for sending input parameters of a wind driven generator obtained through simulation to the wind driven generator simulation module, the wind driven generator simulation module is used for carrying out simulation operation according to the received input parameters, and the grid-connected module is used for controlling the wind driven generator simulation module to be connected with a microgrid simulation source and a local power grid. The wind power generation semi-physical simulation system is closer to a wind power generation semi-physical simulation system under the actual condition, reduces errors generated in the simulation process, can simulate a changeable wind power environment, and meanwhile improves the accuracy of the simulation system.
Description
Technical Field
The invention relates to the field of simulation of wind power generation systems, in particular to a microgrid semi-physical simulation system and a wind power generator closed-loop control method.
Background
The experimental modes for the wind power system mainly include three types: software simulation experiment, field experiment and semi-physical simulation experiment. The field experiment is a condition which can reflect the real working condition most, the obtained data is real and reliable, but the implementation cost is high, the difficulty is large, and the field experiment is not suitable for scientific research of the wind power system. Therefore, software simulation or simulation mode combining software and semi-physical is mostly adopted.
The complete wind power simulation system comprises a real-time simulation part, an electromechanical follow-up part and a corresponding simulation strategy of the wind power generator. In the prior art, as in the current wind power system simulation platform, a wind turbine generator test is performed by using a simulation software modeling method. In the basis, wind speed modeling is carried out according to an autoregressive model, and a mathematical model of the wind driven generator is established by adopting curve fitting.
At present, simulation software is generally adopted to respectively model wind driven generators, transmission systems, generators, loads and other components, parameters of the wind turbine generator are obtained through ideal model derivation, and the parameters cannot completely conform to the state in the actual wind power environment. In addition, because the wind motor transmission system adopts software simulation, the existence of influence factors such as friction coefficient, inertia and the like cannot be accurately reflected, and the actual power, torque and other numerical values of the generator deviate from the actual situation; and the implementation cost is high, the difficulty is large, and in addition, because the external environment is unstable, the safety risk is easily caused. Therefore, field experiments are not suitable for scientific research of wind power systems.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a microgrid semi-physical simulation system and a wind driven generator closed-loop control method, which are closer to a wind power generation semi-physical simulation system under the actual condition, reduce the error generated in the simulation process, can simulate the changeable wind power environment and simultaneously increase the accuracy of the simulation system.
In order to solve the technical problems, the invention provides the following technical scheme:
in one aspect, the present invention provides a microgrid semi-physical simulation system, including: the system comprises an input parameter control module, a wind driven generator simulation module and a grid-connected module which are connected in sequence;
the input parameter control module is used for sending the input parameters of the wind driven generator obtained by simulation to the wind driven generator simulation module;
the wind driven generator simulation module is used for carrying out simulation operation according to the received input parameters;
and the grid-connected module is used for controlling the wind driven generator simulation module to access the micro-grid simulation source and the local grid.
Further, the input parameter control module comprises: the system comprises a wind driven generator real-time simulator, a direct current motor controller and a power supply;
the wind driven generator real-time simulator is used for acquiring input parameters of the wind driven generator by adopting a wind driven generator closed-loop control method according to output parameters of the wind driven motor and sending the input parameters to the direct current motor controller;
the direct current motor controller controls the wind driven generator simulation module to perform simulation operation according to the input parameters;
the power supply is respectively connected with the real-time simulator of the wind driven generator and the direct current motor controller;
wherein the output parameters comprise different wind power environments, output torque and rotating speed of the wind power motor; the input parameters include armature current and rotational speed.
Further, the wind power generator simulation module comprises: the direct current motor, the transmission mechanism and the generator are connected in sequence;
the direct-current motor is in communication connection with the direct-current motor controller, and the operation of the wind-driven motor is simulated according to input parameters sent by the direct-current motor controller, so that the output power and the output torque of the direct-current motor are the same as those of the wind-driven motor;
the two sides of the transmission mechanism are respectively connected with the rotating ends of the direct current motor and the generator;
the generator generates alternating current with variable amplitude and frequency according to synchronous operation of the transmission mechanism and the direct current motor, and transmits the alternating current with variable amplitude and frequency to the grid-connected module.
Furthermore, a speed sensor is arranged on the direct current motor and is in communication connection with the direct current motor controller, and the speed and the acceleration of the direct current motor during operation are sent to the direct current motor controller.
Further, the transmission mechanism is a gear box, and the gear box transmits the action generated by the direct current motor to the rotating end of the generator.
Further, the grid-connected module includes: the system comprises an inverter, a micro-grid real-time simulator, a generator controller and an RLC anti-islanding load which are connected to a power grid respectively;
one end of the inverter is connected with the output end of the generator, the other end of the inverter is respectively connected with the micro-grid real-time simulator, the inverter converts the received alternating current with the amplitude and frequency change into direct current electric energy through a current conversion system, and then the direct current electric energy is converted into sine wave current with the same frequency and the same phase as the local power grid and is input into the local power grid;
the generator controller is in communication connection with the generator;
the micro-grid real-time simulator is used for setting grid change parameters;
the island mode of the RLC anti-island load is a mode combining an active anti-island mode and a passive anti-island mode;
wherein the grid change parameter comprises: frequency drift and voltage jump parameters.
Further, the dc motor is a brushless dc motor BLDCM.
In another aspect, the present invention provides a wind turbine closed-loop control method based on the system, including:
step 1, the real-time simulator of the wind driven generator obtains the rotating speed of a direct current motor and a preset gear ratio according to the speed sensor and determines the rotating speed of the wind driven generator;
step 2, the wind driven generator calculates to obtain the pneumatic torque of the wind driven generator according to the rotating speed of the wind driven generator and a preset wind speed;
and 3, the real-time simulator of the wind driven generator sends the pneumatic torque of the wind driven generator to the direct current motor controller.
Further, the method further comprises:
and 4, the DC motor controller adjusts the armature voltage of the DC motor according to the pneumatic torque of the wind driven generator, so that the output torque of the wind driven generator simulation module is the same as the pneumatic torque of the wind driven generator.
Further, step 1 is preceded by:
step 0, determining an electromagnetic torque feedback value of the wind driven generator according to the back electromotive force, the phase current and the rotating speed of the direct current motor;
the phase current is obtained according to a phase current sensor and a rotating speed sensor which are arranged on the direct current motor, and the counter electromotive force is obtained according to a synovial membrane observer which is arranged on the direct current motor.
According to the technical scheme, the microgrid semi-physical simulation system comprises an input parameter control module, a wind driven generator simulation module and a grid connection module, wherein the input parameter control module is used for sending input parameters of a wind driven generator obtained through simulation to the wind driven generator simulation module, the wind driven generator simulation module is used for carrying out simulation operation according to the received input parameters, and the grid connection module is used for controlling the wind driven generator simulation module to be connected to a microgrid simulation source and a local power grid. The wind power generation semi-physical simulation system is closer to a wind power generation semi-physical simulation system under the actual condition, reduces errors generated in the simulation process, can simulate a changeable wind power environment, and meanwhile improves the accuracy of the simulation system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an embodiment of a microgrid semi-physical simulation system according to a first embodiment of the present invention;
fig. 2 is a schematic structural diagram of an embodiment of the input parameter control module 10 according to a second embodiment of the present invention;
fig. 3 is a schematic structural diagram of a wind turbine simulation module 20 according to a third embodiment of the present invention;
fig. 4 is a schematic structural diagram of a specific embodiment of a grid-connected module 30 according to a fourth embodiment of the present invention;
FIG. 5 is a schematic flow chart of a fifth embodiment of a wind turbine closed-loop control method according to the present invention;
fig. 6 is a schematic structural diagram of a microgrid semi-physical simulation system in an embodiment of the present invention;
FIG. 7 is a schematic diagram of the relationship between the motor torque T and the pneumatic torque T in an exemplary embodiment of the invention;
fig. 8 is a schematic diagram of the relationship between the simulated motor torque and the aerodynamic torque in a specific application example of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a specific implementation mode of a microgrid semi-physical simulation system. Referring to fig. 1, the simulation system specifically includes the following:
the system comprises an input parameter control module 10, a wind driven generator simulation module 20 and a grid-connected module 30 which are connected in sequence.
The input parameter control module 10 is configured to send the input parameters of the wind turbine generator 23 obtained through simulation to the wind turbine generator simulation module 20.
In the input parameter control module 10, different wind power environments are set by the real-time wind power generator simulator 11, and the output of the brushless direct current motor 21BLDCM is controlled to be the same as the output of the wind power generator 23 by adopting a torque closed loop simulation strategy according to the output torque and the rotation speed characteristics of the wind power generator 23.
And the wind driven generator simulation module 20 is configured to perform simulation operation according to the received input parameters.
In the wind power generator simulation module 20, the direct current motor 21 drives the generator 23 through the transmission mechanism 22, so as to reproduce the running state of the wind power generator set in the actual environment.
The grid-connected module 30 is configured to control the wind turbine simulation module 20 to access a microgrid simulation source and a local power grid.
In the grid-connected module 30, a virtual microgrid simulation system is used in a grid-connected part, the wind driven generator is connected to a microgrid simulation source through an inverter 31 and then connected to a local power grid, and the running stability of the wind driven generator in the microgrid is evaluated.
As can be seen from the above description, embodiments of the present invention reduce errors generated during the simulation. The wind power simulation device is suitable for simulating variable wind power environment, and is an efficient and feasible novel technical scheme.
The second embodiment of the present invention provides a specific implementation manner of the input parameter control module 10 in the simulation system. Referring to fig. 2, the input parameter control module 10 specifically includes the following contents:
the system comprises a wind driven generator real-time simulator 11, a direct current motor controller 12 and a power supply 13.
The real-time wind power generator simulator 11 is configured to obtain input parameters of the wind power generator 23 by using a wind power generator closed-loop control method according to output parameters of the wind power motor, and send the input parameters to the dc motor controller 12.
And the direct current motor controller 12 controls the wind driven generator simulation module 20 to perform simulation operation according to the input parameters.
The power supply 13 is respectively connected with the real-time simulator 11 of the wind driven generator and the direct current motor controller 12; wherein the output parameters comprise different wind power environments, output torque and rotating speed of the wind power motor; the input parameters include armature current and rotational speed.
As can be seen from the above description, the embodiment of the present invention implements setting different wind environments by using the real-time wind power generator simulator, and controlling the output of the brushless dc motor BLDCM to be the same as the output of the wind power generator by using the torque closed-loop simulation strategy according to the output torque and rotation speed characteristics of the wind power generator.
The third embodiment of the invention provides a specific implementation manner of the wind driven generator simulation module 20 in the simulation system. Referring to fig. 3, the wind turbine simulation module 20 specifically includes the following contents:
a direct current motor 21, a transmission mechanism 22 and a generator 23 which are connected in sequence;
the speed sensor 24 is arranged on the dc motor 21, and the speed sensor 24 is in communication connection with the dc motor controller 12, and sends the speed and the acceleration of the dc motor 21 during operation to the dc motor controller 12, where the dc motor 21 is a brushless dc motor BLDCM.
The direct current motor 21 is connected with the direct current motor controller 12 in a communication mode, and the operation of the wind power motor is simulated according to input parameters sent by the direct current motor controller 12, so that the output power and the output torque of the direct current motor 21 are the same as those of the wind power motor.
Two sides of the transmission mechanism 22 are respectively connected with the rotating ends of the direct current motor 21 and the generator 23; the transmission mechanism 22 is a gear box, and the gear box transmits the motion generated by the dc motor 21 to the rotating end of the generator 23.
The generator 23 generates ac power of varying amplitude and frequency according to the synchronous operation of the transmission mechanism 22 and the dc motor 21, and transmits the ac power of varying amplitude and frequency to the grid-connection module 30.
As can be seen from the above description, the brushless dc motor in the embodiment of the present invention has the advantage of easy control and a wider variable speed constant frequency operating range, and simulating a wind turbine with the brushless dc motor is a novel efficient and feasible solution.
The fourth embodiment of the present invention provides a specific implementation manner of the grid-connected module 30 in the simulation system. Referring to fig. 4, the grid-connected module 30 specifically includes the following contents:
an inverter 31, a microgrid real-time simulator 32, a generator controller 33 and an RLC anti-islanding load 34, each connected to the grid.
One end of the inverter 31 is connected with the output end of the generator 23, the other end of the inverter 31 is connected with the microgrid real-time simulator 32, the inverter 31 converts the received alternating current with the amplitude and frequency change into direct current electric energy through a current conversion system, and then converts the direct current electric energy into sine wave current with the same frequency and the same phase as the local power grid, and inputs the sine wave current into the local power grid.
The generator controller 33 is communicatively coupled to the generator 23.
The microgrid real-time simulator 32 is used for setting grid variation parameters.
The island mode of the RLC anti-island load 34 is a mode combining active anti-island and passive anti-island. Wherein the grid change parameter comprises: frequency drift and voltage jump parameters.
From the above description, it can be known that the embodiment of the present invention is not connected to a single load any more, but is incorporated into a power grid through an inverter and a high-power microgrid real-time simulator, and not only can the most basic static characteristic observation be completed, but also the observation of the dynamic change characteristic of the wind power system can be realized by utilizing the controllable load torque regulation.
The fifth embodiment of the invention provides a specific implementation mode of the wind driven generator closed-loop control method in the simulation system. Referring to fig. 5, the method for closed-loop control of a wind turbine specifically includes the following steps:
step 000: an electromagnetic torque feedback value of the wind turbine generator 23 is determined based on the back electromotive force, the phase current, and the rotational speed of the dc motor 21.
In step 000, the phase current is obtained according to a phase current sensor and a rotational speed sensor provided on the dc motor 21, and the counter electromotive force is obtained according to a synovial observer provided on the dc motor 21.
Step 100: the real-time simulator 11 of the wind driven generator obtains the rotating speed of the direct current motor 21 and a preset gear ratio according to the speed sensor, and determines the rotating speed of the wind driven generator 23.
Step 200: the wind driven generator 23 calculates the aerodynamic torque of the wind driven generator 23 according to the rotating speed of the wind driven generator 23 and a preset wind speed.
Step 300: the real-time wind power generator simulator 11 sends the pneumatic torque of the wind power generator 23 to the direct current motor controller 12.
Step 400: the dc motor controller 12 adjusts the armature voltage of the dc motor 21 according to the pneumatic torque of the wind power generator 23 so that the output torque of the wind power generator simulation module 20 is the same as the pneumatic torque of the wind power generator 23.
From the above description, it can be seen that embodiments of the present invention employ a torque closed loop simulation strategy such that the brushless dc motor BLDCM is the same as the wind turbine output.
For further explaining the scheme, the invention further provides a specific application example of the microgrid semi-physical simulation system, a specific structure of the system is shown in fig. 6, and the specific application example of the simulation system comprises the following contents:
the simulation system comprises three parts: the system comprises an input parameter control module, a wind driven generator simulation module and a grid connection module. The specific equipment comprises: the system comprises a wind driven generator real-time simulator, a brushless direct current motor BLDCM controller, a generator controller, a high-power feedback type power grid simulation source, a wind driven generator grid-connected inverter and an RLC anti-islanding load. And a direct current motor, a transmission mechanism and a generator which are all real objects.
Different wind power environments are set by using a real-time simulator of the wind driven generator, and the output of the brushless direct current motor BLDCM is controlled to be the same as the output of the wind driven generator by adopting a torque closed-loop simulation strategy according to the output torque and rotating speed characteristics of the wind driven generator. The direct current motor drives the generator through the transmission mechanism, and the running state of the wind generating set in the actual environment is reproduced. And the grid-connected part uses a virtual microgrid simulation system, the wind driven generator is connected to a microgrid simulation source through an inverter and then connected to a local power grid, and the running stability of the wind driven generator in the microgrid is evaluated.
The technical scheme is further realized by adopting the following steps:
the power supply is connected with the controller through a cable. The controller is connected with the control motor through a cable. The generator is connected with the inverter through a cable. The generator is connected with the power grid simulation source through a cable. The real-time simulation part is communicated with the generator controller by adopting a serial port. The real-time simulation part and the direct current motor controller adopt CAN communication.
The DC motor BLDCM controller and the generator controller can adopt an ACS800 of ABB company, and the real-time simulator can adopt a PXIe-8133 quad-core embedded controller of NI company.
The microgrid real-time simulator and the wind motor grid-connected inverter can adopt products of the Xian Aike Saibo electric company Limited. The RLC anti-islanding load can adopt a TC-3087 anti-islanding device of a special power company.
The real-time simulator of the wind driven generator adopts a pneumatic model of the wind driven generator to model the wind driven generator, two quantities of a tip speed ratio lambda and a blade pitch angle β are introduced to calculate the wind energy utilization coefficient of the wind driven generator, and the wind energy utilization coefficient C is usedpRepresenting the ratio of the wind energy absorbed by the wind generator to the wind energy passing through the wind turbine. The pneumatic torque is related to wind energy absorbed by the wind driven generator and the rotating speed of the wind driven generator, and the formula is as follows:
wherein R is the blade radius of the wind driven generator, n is the rotating speed of the wind driven generator, and v is the wind speed. Using curve fitting method to establish Cp(λ, β) the value of the wind energy utilization factor is known.
Pw＝0.5ρStν3Cp；
In the formula StSweep area for the wind turbine, ρ is air density. The pneumatic torque may be calculated by the following equation:
the BLDCM direct current motor simulates the operation of the wind driven generator through torque tracking, and ensures that the output power and the output torque of the direct current motor are the same as those of the wind driven generator. The output torque and output power of the dc motor can be expressed as:
the DC motor controller adopts armature current IaAnd the rotation speed n as two control amounts. The specific implementation process is as follows: and (3) using a speed sensor to obtain the rotating speed of the motor through feedback, and obtaining the rotating speed of the wind driven generator through the rotating speed of the motor and a given gear ratio. Setting wind simulation conditions, setting wind speed, parameters of the wind driven generator and the like, further calculating a tip speed ratio lambda, and solving the pneumatic torque according to the wind energy utilization coefficient of the wind driven generator. By adjusting the armature voltage U, the armature current is changed to make the output torque T of the DC motoreThe aerodynamic torque of the wind driven generator is the same.
The direct current motor controller realizes the modulation of the electromagnetic power by modulating the duty ratio. Because the BLDCM has phase inversion, there are two-phase conduction and three-phase conduction. Two-phase conduction is generally employed.
In the microgrid semi-physical simulation system, the wind power simulation part adopts torque closed-loop control. The premise of realizing the torque closed-loop control is that an electromagnetic torque feedback value of the motor needs to be accurately obtained, the electromagnetic torque of the BLDCM is obtained through back electromotive force, phase current and rotating speed, and the phase current and the rotating speed are detected by corresponding sensors.
In the wind turbine simulation part, the acquisition of the back electromotive force is the key for calculating the electromagnetic torque. The adopted method is a slip film observer which has strong resistance to noise and disturbance of the system and can accurately acquire the back electromotive force.
The transmission mechanism simulation part calculates the friction and other losses of the simulation motor and the wind driven generator when simulating the static characteristics, and corrects the original torque closed-loop simulation strategy by using the friction coefficients under the two conditions. Referring to fig. 7, motor torque TeWith pneumatic torque TMThe relationship is as follows:
Te＝Tw'-(BW'-BM)ω
wherein, TW' and BW' is a value obtained by converting the pneumatic torque and the friction coefficient of the wind turbine into a transmission shaft, BMTo simulate the coefficient of friction of the motor.
The transmission mechanism simulation part considers the condition that the wind speed changes along with time or the load changes when simulating the dynamic characteristic. Referring to fig. 8, the simulated motor torque and the pneumatic torque are related as follows:
and the transmission mechanism simulation part needs to feed back the running acceleration of the simulation motor besides the rotating speed when simulating the dynamic characteristic. When the wind speed or the load changes, the rotating speed of the wind driven generator has a dynamic change process, and acceleration is generated. The speed sensor and the acceleration sensor are used for realizing the feedback of the speed and the acceleration, and the torque closed-loop control is carried out on the direct current motor, so that the accurate simulation of the output torque of the wind driven generator can be realized.
The transmission mechanism simulation part adopts a gear box to improve the rotating speed of the generator. A simulation closer to the actual wind system is performed.
The wind motor grid-connected inverter converts alternating current with amplitude and frequency change generated by a wind driven generator into direct current through a current conversion system, and then converts direct current electric energy into sine wave current with the same frequency and the same phase as a power grid. Through the process of rectifying and inverting firstly, the unstable electric energy generated by the wind driven generator is converted into high-quality stable electric energy to be fed into a power grid.
The microgrid real-time simulator is developed aiming at the performance detection of a wind motor grid-connected inverter, and provides functions of voltage/frequency response characteristic, zero/low voltage ride through simulation, electric energy quality index simulation and the like. The power supply can simulate the general changes of frequency and voltage in a power grid, and can simulate voltage sag, short-time interruption, flicker, frequency drift, three-phase voltage unbalance and the like of mains supply.
The micro-grid real-time simulator is used for setting the change conditions of the power grid such as frequency drift, voltage mutation and the like so as to observe the dynamic change process of the wind turbine parameters under the condition of changing the load of the power grid, and displaying the parameter waveform on the monitor, thereby facilitating data analysis. The equipment adopts a three-phase decoupling design, and the voltage, frequency and other parameter states of each phase can be respectively adjusted.
The RLC anti-islanding load is the most important project for grid-connected safety protection. Usually, a mode of combining an active anti-islanding mode and a passive anti-islanding mode is adopted to realize linkage protection.
From the above description, the present invention replaces the original full software simulation system with the semi-physical simulation system, and uses the physical parts as follows: brushless DC motor, drive mechanism and generator. The wind motor is not connected with a single load any more, but is merged into a power grid through the inverter and the high-power micro-grid real-time simulator, and the most basic static characteristic observation can be completed and the observation of the dynamic change characteristic of the wind power system can be realized by utilizing the controllable load torque regulation. The existing simulation system only considers the change of the input end or only considers the change of the load end during the dynamic characteristic simulation. The system can realize the synchronous control of the input end and the load end. The real-time simulator of the wind driven generator serves as an input end, and control over output torque of the generator can be achieved. The micro-grid real-time simulator is used as a load end, and can realize control of load change conditions.
To further explain the scheme, the invention also provides a specific application example of the simulation method of the wind driven generator grid-connected semi-physical simulation system, and the specific application example of the simulation method comprises the following contents:
s1: inputting wind environment and wind power generator model parameters (including wind speed, air density, physical parameters of the wind power generator and the like) into a real-time simulator of the wind power generator;
s2: the method comprises the steps of setting a wind motor and a load torque in a microgrid, controlling the motor to be connected with an inverter and the microgrid real-time simulator by using a generator controller, supplying power by using a local power grid, and stably operating under a given initial condition.
S3: the real-time simulator of the wind driven generator calculates the pneumatic torque output by the wind driven generator according to the wind power parameters and the motor rotating speed measured by the sensor, and displays the torque value;
s4: through serial port communication with the real-time simulator of the wind driven generator, the direct current motor controller reads a torque value and performs torque closed-loop control on the simulation motor, so that the output torque of the simulation motor is the same as that of the simulated wind driven generator;
s5: through the transmission mechanism, the simulation motor drives the generator to operate, so that the simulation of wind power generation is realized;
s6: and selecting simulation conditions of the wind power system. The static characteristics simulation performs step B1 and the dynamic characteristics simulation performs step B2.
Wherein, B1: and the wind power system stably operates under the static characteristic simulation condition. And setting parameters of a real-time simulator of the wind driven generator to keep the wind speed unchanged. And simultaneously, setting parameters of the microgrid real-time simulator, keeping the load unchanged, and observing the change process of the torque and the rotating speed of the motor through the rotating speed and the torque feedback curve of the sensor.
B2: the dynamic behavior simulation includes two major aspects. One aspect is the simulation of input wind speed fluctuations, step C1 is performed. Another aspect is the simulation of load side fluctuations, step C2 is performed.
C1: in the real-time simulator of the wind driven generator, the condition of wind speed change is set, for example, the wind speed is stepped from 5m/s to 7 m/s. And meanwhile, the micro-grid real-time simulator is controlled to keep the load torque constant. And observing the change process of the rotating speed and the torque of the motor through a rotating speed and torque feedback curve of the sensor.
C2: in the micro-grid real-time simulator, conditions of sudden load change are set, for example, the single-phase voltage of a power grid is halved, or fault conditions such as short circuit and open circuit of a branch circuit are set. And meanwhile, the real-time simulator of the wind driven generator is controlled to keep the wind speed constant. And observing the change process of the rotating speed and the torque of the motor through a rotating speed and torque feedback curve of the sensor.
S1-S6 are initial condition setting parts, and a step-by-step starting process of wind power generation is simulated by using a preset wind power environment. According to the rotating speed and the torque feedback curve of the sensor, when the parameters are relatively stable, the subsequent steps can be executed.
B1-B2 are selected parts of system characteristics, and two characteristics of steady state and dynamic state are introduced to realize observation of various system change conditions.
C1-C2 are the core part of the technical scheme. Namely, the simulation of a dynamic process is considered, and the semi-physical simulation system of the experiment is compared with the existing software simulation system. Setting two conditions of wind speed mutation and load mutation, wherein theoretical values are the due torque and rotating speed of the actual high-speed shaft of the fan under experimental conditions, and the theoretical values are calculated by a real-time simulator of the wind driven generator. The experimental value is a fan torque and rotating speed curve fed back by the sensor.
For the case where the load remains stable and the wind speed is abruptly changed. Due to the existence of mechanical inertia, the rotating speed of the wind driven generator cannot be obviously changed, and the sudden change of the torque of the wind driven generator is caused by the sudden change of the wind speed. And then the rotating speed of the unit changes along with the change of the rotating speed of the unit, the torque of the wind driven generator is gradually balanced with the load torque, and the unit enters a steady state again.
For the case of a sudden load change, the wind speed remains stable. For example, the generator load torque suddenly increases, at which time the unit speed slowly decreases while the wind generator torque gradually increases until it is again balanced with the load torque.
As can be seen from the above description, the acceleration feedback loop is introduced, the electromagnetic torque of the simulation motor receives the acceleration feedback effect, the output torque of the wind driven generator is corrected, and the slow speed change process caused by inertia is considered. No matter the wind speed is suddenly changed or the load is suddenly changed, the result of the simulation system can be well consistent with the actual theoretical value. The simulation accuracy of the software simulation system is effectively improved. For the input end, the conditions of constant load and sudden change of wind speed can be set, and the dynamic characteristic observation is carried out according to the rotating speed and the torque feedback curve of the sensor. For the load end, the conditions of constant wind speed and sudden load change can be set, and dynamic characteristic observation is carried out according to the rotating speed and the torque feedback curve of the sensor. Compared with the traditional single-load simulation system, the simulation of more load end change conditions is provided. Including voltage sags, short interruptions, short circuits, frequency drift, three-phase voltage imbalances, and the like. The method has the advantages that wider observation of grid-connected fault conditions is realized, and the method has excellent reference for the practical application of the wind turbine in the power supply process.
The above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A microgrid semi-physical simulation system is characterized by comprising: the system comprises an input parameter control module, a wind driven generator simulation module and a grid-connected module which are connected in sequence;
the input parameter control module is used for sending the input parameters of the wind driven generator obtained by simulation to the wind driven generator simulation module;
the wind driven generator simulation module is used for carrying out simulation operation according to the received input parameters;
the grid-connected module is used for controlling the wind driven generator simulation module to access a micro-grid simulation source and a local grid;
wherein, the wind power generator simulation module comprises: the direct current motor, the transmission mechanism and the generator are connected in sequence;
the direct current motor is in communication connection with the direct current motor controller, and the operation of the wind power motor is simulated according to the input parameters sent by the direct current motor controller, so that the output power and the output torque of the direct current motor are the same as those of the wind power motor;
the two sides of the transmission mechanism are respectively connected with the rotating ends of the direct current motor and the generator;
the generator generates alternating current with variable amplitude and frequency according to the synchronous operation of the transmission mechanism and the direct current motor, and transmits the alternating current with variable amplitude and frequency to the grid-connected module;
the direct current motor is a brushless direct current motor BLDCM;
and controlling the brushless direct current motor BLDCM to output the same as the output of the generator by adopting a torque closed-loop simulation strategy according to the output torque and rotating speed characteristics of the generator.
2. The system of claim 1, wherein the input parameter control module comprises: the system comprises a wind driven generator real-time simulator, a direct current motor controller and a power supply;
the wind driven generator real-time simulator is used for acquiring input parameters of the wind driven generator by adopting a wind driven generator closed-loop control method according to output parameters of the wind driven motor and sending the input parameters to the direct current motor controller;
the direct current motor controller controls the wind driven generator simulation module to perform simulation operation according to the input parameters;
the power supply is respectively connected with the real-time simulator of the wind driven generator and the direct current motor controller;
wherein the output parameters comprise different wind power environments, output torque and rotating speed of the wind power motor; the input parameters include armature current and rotational speed.
3. The system of claim 1, wherein a speed sensor is provided on the dc motor and is in communication with the dc motor controller to transmit the speed and acceleration of the dc motor during operation to the dc motor controller.
4. The system of claim 1, wherein the transmission mechanism is a gearbox and the gearbox transmits motion generated by the dc motor to the rotating end of the generator.
5. The system of claim 1, wherein the grid tie module comprises: the system comprises an inverter, a micro-grid real-time simulator, a generator controller and an RLC anti-islanding load which are connected to a power grid respectively;
one end of the inverter is connected with the output end of the generator, the other end of the inverter is respectively connected with the micro-grid real-time simulator, the inverter converts the received alternating current with the amplitude and frequency change into direct current electric energy through a current conversion system, and then the direct current electric energy is converted into sine wave current with the same frequency and the same phase as the local power grid and is input into the local power grid;
the generator controller is in communication connection with the generator;
the micro-grid real-time simulator is used for setting grid change parameters;
the island mode of the RLC anti-island load is a mode combining an active anti-island mode and a passive anti-island mode;
wherein the grid change parameter comprises: frequency drift and voltage jump parameters.
6. A wind turbine closed-loop control method based on the system of claim 1, comprising:
step 1, the real-time simulator of the wind driven generator obtains the rotating speed of a direct current motor and a preset gear ratio according to a speed sensor and determines the rotating speed of the wind driven generator;
step 2, the wind driven generator calculates to obtain the pneumatic torque of the wind driven generator according to the rotating speed of the wind driven generator and a preset wind speed;
and 3, the real-time simulator of the wind driven generator sends the pneumatic torque of the wind driven generator to the direct current motor controller.
7. The method of claim 6, further comprising:
and 4, the DC motor controller adjusts the armature voltage of the DC motor according to the pneumatic torque of the wind driven generator, so that the output torque of the wind driven generator simulation module is the same as the pneumatic torque of the wind driven generator.
8. The method of claim 6, wherein step 1 is preceded by:
step 0, determining an electromagnetic torque feedback value of the wind driven generator according to the back electromotive force, the phase current and the rotating speed of the direct current motor;
the phase current is obtained according to a phase current sensor and a rotating speed sensor which are arranged on the direct current motor, and the counter electromotive force is obtained according to a synovial membrane observer which is arranged on the direct current motor.
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