CN117081155A - Grid-connected wind power generation low-voltage ride through method and system based on super capacitor - Google Patents
Grid-connected wind power generation low-voltage ride through method and system based on super capacitor Download PDFInfo
- Publication number
- CN117081155A CN117081155A CN202311076811.5A CN202311076811A CN117081155A CN 117081155 A CN117081155 A CN 117081155A CN 202311076811 A CN202311076811 A CN 202311076811A CN 117081155 A CN117081155 A CN 117081155A
- Authority
- CN
- China
- Prior art keywords
- super capacitor
- fluctuation
- voltage
- control
- power
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003990 capacitor Substances 0.000 title claims abstract description 106
- 238000000034 method Methods 0.000 title claims abstract description 57
- 238000010248 power generation Methods 0.000 title claims abstract description 31
- 238000004146 energy storage Methods 0.000 claims abstract description 15
- 230000008569 process Effects 0.000 claims abstract description 10
- 238000007665 sagging Methods 0.000 claims abstract description 7
- 238000004590 computer program Methods 0.000 claims description 13
- 230000001629 suppression Effects 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 11
- 230000010485 coping Effects 0.000 claims description 9
- 238000012937 correction Methods 0.000 claims description 5
- 230000001360 synchronised effect Effects 0.000 claims description 5
- 238000011217 control strategy Methods 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims 1
- 230000008859 change Effects 0.000 abstract description 7
- 230000005764 inhibitory process Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 11
- 230000006870 function Effects 0.000 description 11
- 239000013598 vector Substances 0.000 description 7
- 238000004364 calculation method Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
- H02J2003/365—Reducing harmonics or oscillations in HVDC
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Control Of Eletrric Generators (AREA)
Abstract
The application provides a grid-connected wind power generation low-voltage ride through method and system based on a super capacitor, which considers high-frequency fluctuation of a fan and voltage fluctuation of a direct current bus caused by uncontrolled rotor rotating speed due to randomness of offshore wind energy, obtains power references of an unloading resistor and the super capacitor by introducing virtual impedance sagging control at a motor side, absorbs high-frequency fluctuation power sent by the fan by the unloading resistor, absorbs constant power generated by the fan by the super capacitor, and realizes inhibition of the high-frequency fluctuation and the voltage fluctuation of the direct current bus under random wind speed in the low-voltage ride through process of a wind turbine generator; the super capacitor is controlled by adopting a virtual resistor, and the unloading resistor is controlled by adopting the virtual capacitor so as to achieve a control target; the high-inertia fan rotor is difficult to respond to wind speed change in real time, the rotating speed is uncontrolled due to rotor energy storage, and the rotating speed after mismatching of the rotating speed change and the direct current bus voltage fluctuation are solved.
Description
Technical Field
The disclosure relates to the technical field of offshore high-power wind power generation, in particular to a grid-connected wind power generation low-voltage ride-through method and system based on a super capacitor.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The low voltage ride through means that when the power grid fails, the voltage of the grid-connected point of the fan drops, the fan can continue to keep running without off-grid, and even a certain reactive power support is provided for the power grid until the power grid returns to normal. When the wind power plant does not have low voltage ride through capability, when voltage drops caused by power grid faults, a large number of wind power units are disconnected, the tide of the system is seriously offset, and the stable operation of the system is not facilitated, so that the wind power units have certain low voltage ride through capability.
The method is generally a low-voltage ride-through method based on a super capacitor, the super capacitor is charged during low-voltage ride-through of a fan, and after the low-voltage ride-through is finished, the super capacitor is matched with a grid-side converter to release electric energy to a power grid. The fan has low voltage ride through capability and simultaneously reduces the loss to the minimum.
However, in the traditional low-voltage ride through scheme, when the wind turbine generator is subjected to low-voltage ride through, the direct-current bus voltage is controlled through the machine side converter, and the rotor energy storage is used for treating small voltage drop, but at the moment, due to randomness of offshore wind energy and uncontrolled rotor rotating speed, the rotor rotating speed and wind speed are mismatched, high-frequency fluctuation is generated, and then the direct-current bus voltage fluctuation is caused, so that the reliability of a wind power generation system is reduced.
Disclosure of Invention
In order to solve the problems, the disclosure provides a grid-connected wind power generation low voltage ride through method and system based on super-capacitor, the method is a low voltage ride through (LowVoltage Ride Through, LVRT) method based on super-capacitor frequency division droop control, on the basis of using rotor energy storage to cope with short-time voltage drop and super-capacitor energy storage to cope with long-time voltage drop, high-frequency fluctuation power sent by a fan is absorbed by an unloading resistor through virtual impedance droop control, constant power generated by the fan is absorbed by the super-capacitor to reduce bus voltage fluctuation, meanwhile, the capacity of model prediction control multi-objective optimization is utilized to predict rotating speed, and rotating speed fluctuation caused by wind energy randomness is reduced.
According to some embodiments, the present disclosure employs the following technical solutions:
a grid-connected wind power generation low voltage ride through method based on super capacitor comprises the following steps:
when the wind turbine generator is subjected to low-voltage ride through, rotor energy storage is used for coping with short-time voltage drop, super-capacitor is used for absorbing energy for coping with long-time voltage drop, high-frequency fluctuation of the rotating speed of the wind turbine generator and direct-current bus voltage fluctuation caused by uncontrolled rotating speed of the rotor due to randomness of offshore wind energy are considered, virtual impedance droop control is introduced in crowbar circuit control to obtain power references of an unloading resistor and the super-capacitor, the unloading resistor is used for absorbing high-frequency fluctuation power sent by the wind turbine generator, the super-capacitor is used for absorbing constant power which is generated by the wind turbine generator, and meanwhile, rotating speed fluctuation punishment items are introduced in motor side control to realize high-frequency rotating speed fluctuation suppression and direct-current bus voltage fluctuation suppression of the wind turbine generator in the low-voltage ride through process under random wind speed;
in the virtual impedance sagging control, the super capacitor is controlled by adopting a virtual resistor, and the unloading resistor is controlled by adopting the virtual capacitor; in motor side control, the wind turbine generator adopts model predictive current control with rotational speed penalty, virtual impedance droop control and motor side control act together, and fan rotational speed fluctuation and direct current bus voltage fluctuation are reduced.
According to some embodiments, the present disclosure employs the following technical solutions:
grid-connected wind power generation low voltage ride through system based on super capacitor includes:
the low-voltage ride-through control module is used for coping with short-time voltage drop by using rotor energy storage and coping with long-time voltage drop by using super-capacitor energy absorption when the wind turbine generator carries out low-voltage ride-through;
the fluctuation suppression module is used for taking high-frequency fluctuation of the rotating speed of the wind turbine and voltage fluctuation of the direct current bus, which are caused by uncontrolled rotating speed of the rotor due to randomness of offshore wind energy, introducing virtual impedance droop control in crowbar circuit control to obtain power references of an unloading resistor and a super capacitor, absorbing high-frequency fluctuation power sent by the wind turbine by the unloading resistor, absorbing constant power multiple by the wind turbine by the super capacitor, and simultaneously introducing a rotating speed fluctuation penalty term in motor side control to realize high-frequency rotating speed fluctuation suppression and direct current bus voltage fluctuation suppression of the wind turbine in the low-voltage traversing process of the wind turbine;
in the virtual impedance sagging control, the super capacitor is controlled by adopting a virtual resistor, and the unloading resistor is controlled by adopting the virtual capacitor; in motor side control, the wind turbine generator adopts model predictive current control with rotational speed penalty, virtual impedance droop control and motor side control act together, and fan rotational speed fluctuation and direct current bus voltage fluctuation are reduced.
According to some embodiments, the present disclosure employs the following technical solutions:
a non-transitory computer readable storage medium for storing computer instructions that, when executed by a processor, implement the supercapacitor-based grid-connected wind power generation low voltage ride through method.
According to some embodiments, the present disclosure employs the following technical solutions:
an electronic device, comprising: a processor, a memory, and a computer program; the processor is connected with the memory, the computer program is stored in the memory, and when the electronic equipment runs, the processor executes the computer program stored in the memory so that the electronic equipment executes the grid-connected wind power generation low voltage ride through method based on the super capacitor.
Compared with the prior art, the beneficial effects of the present disclosure are:
the Low Voltage ride through (Low Voltage RideThrough, LVRT) method based on super capacitor frequency division droop control is used for coping with short-time Voltage drop by using rotor energy storage and long-time Voltage drop by using super capacitor energy storage under the framework of classical model predictive control. Virtual impedance droop control is introduced in crowbar circuit control, high-frequency fluctuation power emitted by a fan is absorbed by an unloading resistor, and constant power generated by the fan is absorbed by a super capacitor so as to reduce busbar voltage fluctuation. Meanwhile, the capacity of model predictive control multi-objective optimization is utilized, in motor side control, the rotating speed is predicted, and a rotating speed fluctuation punishment item is introduced into a model predictive control cost equation, so that the rotating speed fluctuation generated by wind energy randomness is reduced.
The high-inertia wind turbine rotor is difficult to respond to wind speed change in real time, the rotating speed is uncontrolled due to rotor energy storage, the rotating speed after mismatching of the rotating speed change and the direct current bus voltage fluctuation are solved, and the reliability and the stability of low-voltage ride through of a high-power wind power generation system are greatly improved. The wind energy random wind turbine generator has the advantages that the wind energy random wind turbine generator realizes low voltage ride through of the wind turbine generator, meanwhile, the wind energy random wind turbine generator inhibits the influence of wind energy random wind turbine generator on the low voltage ride through, reduces the fluctuation of rotating speed and a direct current bus, inhibits the mismatching of rotating speed, and provides guarantee for the safe and stable operation of the offshore high-power wind turbine generator.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure.
FIG. 1 is a PMSG wind power system topology of a 3L-NPC converter according to an embodiment of the disclosure;
FIG. 2 is a LVRT control architecture diagram of a conventional PMSG wind power generation system according to an embodiment of the present disclosure;
fig. 2 (a) is a motor-side control method, and fig. 2 (b) is a grid-side control method;
FIG. 3 is a schematic diagram of a crowbar circuit control architecture in accordance with an embodiment of the present disclosure;
fig. 3 (a) is a general system topology diagram, and fig. 3 (b) is a power prediction control method;
FIG. 4 is a control architecture diagram of an MPC method of an embodiment of the present disclosure.
Fig. 4 (a) shows a motor-side control method according to the method of the present application, and fig. 4 (b) shows a grid-side control method according to the method of the present application.
Detailed Description
The disclosure is further described below with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Example 1
In one embodiment of the disclosure, a grid-connected wind power generation low voltage ride through method based on a super capacitor is provided, because the traditional low voltage ride through method controls the voltage of a direct current bus through a motor side converter during low voltage ride through, a rotor is used for storing energy to treat small voltage drop, and the super capacitor is used for treating long-term voltage drop, but at the moment, due to randomness of offshore wind energy and uncontrolled rotor rotating speed, the rotor rotating speed and wind speed are mismatched, high-frequency fluctuation is generated, and then the voltage of the direct current bus is fluctuated, so that the reliability of a wind power generation system is reduced. Therefore, the application provides a PMSG low-voltage ride through strategy based on super capacitor frequency division droop control, and the method also uses rotor energy storage to cope with short-time voltage drop and uses super capacitor to cope with long-time voltage drop. However, virtual impedance droop control is introduced, the unloading resistor is used for absorbing the fan to emit high-frequency fluctuation power, and the super capacitor is used for absorbing the constant power of the fan, so that the voltage fluctuation of the bus is reduced. Meanwhile, a rotational speed fluctuation punishment item is introduced at the motor side, and the rotational speed regression reference value of the next control period is taken as a target adjusting torque, so that the rotational speed fluctuation of the fan is further reduced. The reliability of low voltage ride through of the wind power system is greatly improved, taking a PMSG wind power system of a 3L-NPC converter as an example, the steps of using a PMSG low voltage ride through strategy based on super capacitor frequency division droop control are as follows:
1. the wind turbine generator is a three-level back-to-back direct-drive permanent magnet synchronous wind turbine generator, and a topological crowbar circuit topology structure of the three-level back-to-back direct-drive permanent magnet synchronous wind turbine generator system is constructed. As shown in fig. 1, subscripts m and g represent variables on the motor and grid sides, respectively; { i, e, v, R, L } represents current, grid and converter voltage, resistance and inductance, respectively. V (V) C1 ，V C2 And omega m The voltage of the two capacitors of the direct current bus and the rotating speed of the generator are respectively. P, Q are grid side active power and reactive power, respectively.
The three-level back-to-back converter consists of a pair of 3L-NPC converters connected through a direct current bus, and the output voltage is as follows:
wherein, in the formula:for the switching vector of the converter, ">For outputting three-phase voltage of the power network for the converter, V C1 ，V C2 Is the voltage of the two capacitors on the dc bus. V (V) dc Is the sum of the voltages of two voltage equalizing capacitors on the DC bus of the converter.
Midpoint voltage bias V o The calculation formula of (2) is as follows:
aiming at a three-level back-to-back direct-drive permanent magnet synchronous wind generating set system, the traditional low-voltage ride through control scheme of the wind generating set is to change the control modes of a machine and a grid-side converter, direct-current bus voltage is controlled through the motor-side converter, and grid-side current reference is given according to the standard in the test procedure of fault voltage ride through capability of the wind generating set. And the super capacitor adopts constant power control, and when the power grid voltage is lower than 0.9 times per unit value, the difference value of the power at the motor side and the power at the power grid side is used as reference power for charging. And when the voltage or the rotating speed of the direct current bus is higher than the rated voltage, the super capacitor is charged. And after the power grid voltage is higher than 0.9 times per unit value, the super capacitor discharges.
However, the mechanical torque of the permanent magnet direct drive motor fluctuates due to the complex and changeable wind conditions at sea. In the low-pass process, when the rotating speed reaches the rated rotating speed, the super capacitor is used for absorbing excessive energy, so that the voltage fluctuation of the direct-current bus is stabilized. However, the large inertia fan is difficult to respond to torque fluctuation in real time, electromagnetic torque is difficult to follow mechanical torque, and the rotating speed is delayed from wind speed change. The super capacitor uses the multiple power of the fan at the current moment as reference power and uses the current rotating speed as a triggering condition, so that the rotating speed fluctuation caused by the mismatching of the rotating speed cannot be restrained, and the change of the rotating speed relative to the limit rotating speed can cause the kinetic energy of the rotor to flow in the rotor and the direct current bus. When the rotating speed is too high, the rotor transmits less energy to the direct current bus to reduce the voltage of the bus, and when the rotating speed is too low, the rotor excessively emits energy to the direct current bus to cause the direct current voltage to rise, so that the voltage of the direct current bus fluctuates severely. Therefore, the PMSG low voltage ride through method based on super capacitor frequency division droop control provided by the application can inhibit the generated fluctuation while ensuring stable low voltage ride through, and comprises the following steps:
2. when the wind turbine generator generates low voltage ride through, rotor energy storage is used for coping with short-time voltage drop, super capacitor energy storage is used for coping with long-time voltage drop, high-frequency fluctuation of a fan and direct-current bus voltage fluctuation caused by uncontrolled rotor rotating speed due to randomness of offshore wind energy are considered, power references of an unloading resistor and a super capacitor are obtained through introducing virtual impedance sagging control, high-frequency fluctuation power sent by the fan is absorbed by the unloading resistor, and constant power generated by the fan is absorbed by the super capacitor. Meanwhile, rotation speed fluctuation suppression control is introduced in motor side control, so that high-frequency rotation speed fluctuation and DC bus voltage fluctuation suppression under random wind speed in the low-voltage ride through process of the wind turbine generator are realized.
The crowbar circuit topology and the control method shown in fig. 3, wherein the crowbar circuit comprises switching tubes D1, D2 and D3 and an unloading resistor R1, the switching tubes are controlled by a PI controller, wherein the D1 and the D2 control a super capacitor, and the D3 is a starting switch of the unloading resistor.
Further, specific control strategies are:
(1) If the rotating speed of the fan exceeds the rated value or the voltage of the direct current bus exceeds the limit by more than 5%, and if the super capacitor does not reach the highest voltage, the super capacitor is charged, the unloading resistor assists in absorbing energy, D1 and D3 can be turned on, and D2 is turned off;
(2) If the rotating speed of the fan exceeds the rated value or the voltage of the direct current bus exceeds 5% of the limit, and the super capacitor is full, the super capacitor does not work, and the unloading resistor is suddenly unloaded. D1 and D2 are turned off, and D3 can be turned on;
(3) If the voltage of the direct current bus is reduced to be less than 1% in an out-of-limit mode, and the low voltage crossing state (the power grid voltage is more than or equal to 0.9 times per unit value) is exited, and the super capacitor does not fall to the lowest voltage, the unloading resistor does not work, and the super capacitor discharges. D1, D3 are off and D2 can be on. The fluctuation of the rotating speed of the fan caused by the delay of the wind speed can cause the continuous fluctuation of the multiple power of the fan. At the moment, if fluctuation power caused by rotation speed fluctuation and constant multiple power of the fan are stripped, high-frequency fluctuation power is absorbed through the unloading resistor, and constant power is absorbed through the super capacitor, the rotation speed fluctuation problem under random wind speed can be solved.
Further, the super capacitor is controlled by a virtual resistor, and the unloading resistor is controlled by the virtual capacitor to achieve the proposed control target, and the specific implementation method is as follows:
super capacitor using PI controlController control, P mc 、P gc The power emitted by the machine side and the network side converters in the next control period. The super capacitor basic absorption power at the next moment is obtained through power calculationObtaining a super capacitor absorption power correction value +.>Correcting to obtain super capacitor absorption power reference +.>Charging super capacitor with power P C And->And comparing and sending the signals to a PI controller to obtain the duty ratio of the PWM modulator, and inputting the duty ratio into the PWM modulator to control the switching tube D1 to be switched on and off. The control block diagram is shown in fig. 3 (b). The calculation formula of the DC bus voltage is as follows:
discretizing by using a backward Euler method to obtain the reference charging power of the super capacitorThe method comprises the following steps:
wherein: t (T) s For controlling the period, C is the capacitance of the super capacitor, the suffix (k+1) represents the variable as the predicted value of the next time, and the suffix (k) represents the variable as the current time value. Wherein P is mc (k+1)、P gc (k+1) has been calculated, V dc (k+1) is set to the target DC bus voltage value V dc * ，V dc (k) Is the current DC bus voltage value V dc . The peak of the bus voltage is reduced by this method.
In order to realize frequency division and power absorption, a droop control loop is additionally added to a super capacitor control power loop to adjust the reference power. The virtual resistance of the super capacitor is as follows:
R v1 ＝(U max -U min )\I max
wherein: i max Represents the maximum output current of the battery-side converter, U max And U min Representing the maximum and minimum values, respectively, of the allowable bus voltage fluctuation range of the system. The present disclosure sets the bus voltage fluctuation range to +5% of the rated voltage. Discharge time command for super capacitorIs of a constant value and is provided with the discharge current of the super capacitor not exceeding the limit discharge current i Cmax And the super capacitor is prevented from being damaged.
The unloading resistor refers to the unloading power P of the chopper circuit (crowbar circuit) r * And the active power P absorbed by the unloading resistor under the voltage of the direct current bus at the next moment rm And comparing, sending the comparison result to a PI controller to obtain the duty ratio of the PWM modulator, and controlling the D3 to be turned on and off. The control block diagram is shown in fig. 3 (b). Wherein the unloading resistor basically absorbs power as follows
In order to realize frequency division and power absorption, a droop control loop is additionally arranged outside an unloading resistor control power loop to adjust the reference power. Wherein the virtual capacitance of the dump resistor:
C v1 ＝1\(2πR v1 f c )
f in c The cut-off frequency for the proposed division control is set to 10Hz. Active power correction value DeltaP obtained by droop control r * CorrectionObtaining the reference unloading power P of the circuit r * . In an emergency unloading state, because the super capacitor does not work, only the unloading resistor works, and the power of the unloading resistor is P r * ＝(P mc -P gc ). In this case, the motor-side control method is to obtain a motor-side overall cost function by adding the rotational speed fluctuation control cost function and the stator current control cost function as shown in fig. 4 (a):
substituting the current reference value and the current predicted value obtained under different switching vectors into a cost equation, calculating, selecting a switching vector corresponding to the current predicted value with the smallest cost equation, and acting the switching vector on the system. The specific cost function setting method is as follows:
sensor sampling motor side currentMotor stator flux linkage angle θ, motor rotational speed ω m DC bus voltage V dc . Will->Converted into the dq-axis component of the stator current by Park conversion>Comparing the DC bus voltage with a reference and sending the comparison result to a PI controller to obtain q-axis current +.>Reference->But->Then it is set to 0. Control objective of motor side model predictive controlThe labels are as follows:
(1) Rotational speed fluctuation control: during low voltage ride through, the motor side outer ring is changed from the rotating speed outer ring to the direct current busbar voltage outer ring, so that the rotating speed is difficult to control, and the unstable rotating speed leads to stator currentFluctuation occurs, resulting in dc bus voltage oscillation. Thus, according to the motor dynamics model:
where J is moment of inertia, tt is load torque, te is mechanical torque, B is coefficient of friction, and when the mechanical torque is known, the next moment of time is deduced to restore the rotational speed to the rated rotational speedRequired electromagnetic torque T e Size of the product. Let fan external friction coefficient B be 0, carry out backward Euler discretization, rotational speed and electromagnetic torque initial value be rotational speed and electromagnetic torque when just entering the low state of wearing, can obtain:
wherein: t (T) s To control the period, the mechanical torque T t Given that the suffix (k+1) represents the predicted value of the variable at the next time, and that the q-axis stator current, which is recovered to the given rotational speed at the next time using the torque-current relationship, is obtained by using the variable at the present valueThe method comprises the following steps:
the method is characterized in that a rotational speed fluctuation punishment item is introduced in motor side control, so that high-frequency fluctuation and direct-current bus voltage fluctuation under random wind speed in the low-voltage ride through process of the wind turbine generator are restrained, and a cost function of rotational speed fluctuation control is obtained as follows:
(2) Stator current control: stator current control is a predicted value of stator current at the next moment in dq coordinate systemAnd current reference->And->The square of the difference. The two control targets are combined into one, the priority is highest, and the cost function is as follows:
the power grid side control scheme is as follows:
the net side overall cost equation is:
substituting the current reference value and the current predicted value obtained under different switching vectors into a cost equation, calculating, selecting a switching vector corresponding to the current predicted value with the smallest cost equation, and acting the switching vector on the system. The specific setting method of the network side cost function is as follows:
collecting power grid voltage and currentDC bus voltage V dc And two bus capacitorsVoltage value V of (2) C1 、V C2 . Converting the current and voltage into dq axis coordinate system by Park transformation to obtain +.>And->Current reference->And->The calculation is carried out according to the following formula:
wherein: v N And i N Is the rated value of the voltage and the current of the power grid; i.e max Is the maximum current that the current transformer can withstand. And (3) performing cost function calculation, wherein the control target comprises power grid current control and a voltage difference of a direct current bus capacitor. The control target of the power grid side model predictive control is power grid current control. The current control is the predicted value of the current of the power grid at the next moment under the dq coordinate systemAnd current reference->The square of the difference. By controlling->Control of the dc bus voltage can be achieved. />And the power factor is set to 0, so that the power factor at the power grid side is ensured to be 1. The cost function is as follows:
example 2
In one embodiment of the present disclosure, a grid-connected wind power generation low voltage ride through system based on a super capacitor is provided, including:
the low-voltage ride-through control module is used for using the rotor energy storage to cope with short-time voltage drop and using the super capacitor to cope with long-time voltage drop when the wind turbine generator generates low-voltage ride-through;
the fluctuation suppression module is used for considering high-frequency fluctuation of the wind turbine and voltage fluctuation of the direct current bus caused by uncontrolled rotor rotating speed due to randomness of offshore wind energy, acquiring power references of an unloading resistor and a super capacitor by introducing virtual impedance droop control, absorbing high-frequency fluctuation power sent by the wind turbine by the unloading resistor, absorbing constant power multiple by the wind turbine by the super capacitor, and realizing suppression of high-frequency fluctuation and voltage fluctuation of the direct current bus under random wind speed in the low-voltage ride through process of the wind turbine;
the super capacitor is controlled by a virtual resistor, the unloading resistor is controlled by the virtual capacitor, a rotational speed fluctuation punishment item is introduced, the rotational speed of the next control period is predicted, and the rotational speed of the motor side is regulated by taking the rotational speed regression reference value of the next control period as a target, so that the rotational speed of the motor side is kept within the allowable up-and-down fluctuation range of the rated rotational speed.
Example 3
In one embodiment of the disclosure, a non-transitory computer readable storage medium is provided, where the non-transitory computer readable storage medium is configured to store computer instructions, and when the computer instructions are executed by a processor, the low voltage ride through method based on super capacitor grid-connected wind power generation is implemented.
Example 4
In one embodiment of the present disclosure, there is provided an electronic device including: a processor, a memory, and a computer program; the processor is connected with the memory, the computer program is stored in the memory, and when the electronic equipment runs, the processor executes the computer program stored in the memory so that the electronic equipment executes the grid-connected wind power generation low voltage ride through method based on the super capacitor.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the specific embodiments of the present disclosure have been described above with reference to the drawings, it should be understood that the present disclosure is not limited to the embodiments, and that various modifications and changes can be made by one skilled in the art without inventive effort on the basis of the technical solutions of the present disclosure while remaining within the scope of the present disclosure.
Claims (10)
1. The grid-connected wind power generation low voltage ride through method based on the super capacitor is characterized by comprising the following steps of:
when the wind turbine generator generates low voltage ride through, rotor energy storage is used for coping with short-time voltage drop, a super capacitor is used for coping with long-time voltage drop, high-frequency fluctuation of the rotating speed of the wind turbine generator and direct-current bus voltage fluctuation caused by uncontrolled rotating speed of the rotor due to randomness of offshore wind energy are considered, a crowbar circuit is controlled to acquire power references of an unloading resistor and the super capacitor by introducing virtual impedance sagging control, the unloading resistor is used for absorbing high-frequency fluctuation power sent by the wind turbine generator, the super capacitor is used for absorbing constant power generated by the wind turbine generator, and meanwhile, a rotating speed fluctuation penalty term is controlled to be introduced at the side of a motor, so that the suppression of the high-frequency fluctuation and the direct-current bus voltage fluctuation under random wind speed in the low voltage ride through process of the wind turbine generator is realized;
in the virtual impedance sagging control, the super capacitor is controlled by adopting a virtual resistor, and the unloading resistor is controlled by adopting the virtual capacitor; in motor side control, the wind turbine generator adopts model predictive current control with rotational speed penalty, virtual impedance droop control and motor side control act together, and fan rotational speed fluctuation and direct current bus voltage fluctuation are reduced.
2. The grid-connected wind power generation low voltage ride through method based on the super capacitor according to claim 1, wherein the wind power generation set is a three-level back-to-back direct-drive permanent magnet synchronous wind power generation set, a system topology structure and a crowbar circuit topology structure of the three-level back-to-back direct-drive permanent magnet synchronous wind power generation set are built, and a switch in the crowbar circuit is controlled through a PI controller, so that control of switch starting of charging and discharging of the super capacitor and unloading resistance is achieved.
3. The grid-connected wind power generation low voltage ride through method based on the super capacitor as claimed in claim 2, wherein the crowbar circuit comprises switching tubes D1, D2 and D3 and an unloading resistor, the switching tubes are controlled by a PI controller, the super capacitor is controlled by D1 and D2, and D3 is a start switch of the unloading resistor.
4. The supercapacitor-based grid-connected wind power generation low voltage ride through method of claim 3, wherein the PI controller has a control strategy of:
if the rotating speed of the fan exceeds the rated rotating speed or the voltage of the direct current bus exceeds 5% of the limit, and if the super capacitor does not reach the highest voltage, the super capacitor is charged, the unloading resistor is used for assisting in absorbing energy, D1 and D3 are turned on, and D2 is turned off; if the rotating speed of the fan exceeds the rated rotating speed or the voltage of the direct-current bus exceeds 5% of the limit, and the super capacitor is full, the super capacitor does not work, the unloading resistor is suddenly unloaded, D1 and D2 are disconnected, and D3 is opened; if the voltage of the direct current bus is reduced to be less than 1% in an out-of-limit mode, and the low voltage ride through state is exited, and the super capacitor does not drop to the lowest voltage, the unloading resistor does not work, the super capacitor discharges, D1 and D3 are disconnected, and D2 is opened.
5. The grid-connected wind power generation low voltage ride through method based on the super capacitor according to claim 1, wherein the super capacitor is controlled by a PI controller, power sent by a motor side converter and a grid side converter in a next control period is predicted, basic absorption power of the super capacitor at the next moment is obtained, a super capacitor absorption power correction value is obtained through droop control, a super capacitor absorption power reference is obtained after correction, super capacitor charging power and the absorption power reference are compared, the comparison result is input to the PI controller, the duty ratio of a PWM modulator is obtained, and the PWM modulator is input to control a switching tube D1 to be turned on and off.
6. The method for low voltage ride through based on grid-connected wind power generation of claim 1, wherein, to realize frequency division and power absorption, a droop control loop is additionally added to a control power loop of the super capacitor to adjust the power reference, wherein, the virtual resistance of the super capacitor is as follows:
R v1 ＝(U max -U min )\I max
wherein I is max Represents the maximum output current of the battery-side converter, U max And U min Representing the maximum and minimum values of the allowable DC bus voltage fluctuation range of the system respectively.
7. The grid-connected wind power generation low voltage ride through method based on the super capacitor as claimed in claim 1, wherein the unloading resistor compares the reference unloading power of the crowbar circuit with the active power absorbed by the unloading resistor under the voltage of the direct current bus at the next moment, and sends the comparison result to the PI controller to obtain the duty ratio of the PWM modulator, and controls the on/off of D3, wherein the virtual capacitance of the unloading resistor is:
C v1 ＝1\(2πR v1 f c )
wherein f c Is the cut-off frequency of the frequency division control.
8. Grid-connected wind power generation low voltage ride through system based on super capacitor, characterized by comprising:
the low-voltage ride-through control module is used for using the rotor energy storage to cope with short-time voltage drop and using the super capacitor to cope with long-time voltage drop when the wind turbine generator generates low-voltage ride-through;
the fluctuation suppression module is used for considering high-frequency fluctuation of the rotating speed of the wind turbine and voltage fluctuation of the direct current bus caused by uncontrolled rotating speed of the rotor due to randomness of offshore wind energy, the crowbar circuit is controlled to acquire power references of an unloading resistor and a super capacitor by introducing virtual impedance droop control, the unloading resistor is used for absorbing high-frequency fluctuation power sent by the wind turbine, the super capacitor is used for absorbing constant power which is multiple to the wind turbine, and meanwhile, a rotating speed fluctuation penalty term is introduced by controlling at the motor side, so that the suppression of the high-frequency fluctuation and the direct current bus voltage fluctuation under random wind speed in the low-voltage crossing process of the wind turbine is realized;
in the virtual impedance sagging control, the super capacitor is controlled by adopting a virtual resistor, and the unloading resistor is controlled by adopting the virtual capacitor; in motor side control, the wind turbine generator adopts model predictive current control with rotational speed penalty, virtual impedance droop control and motor side control act together, and fan rotational speed fluctuation and direct current bus voltage fluctuation are reduced.
9. A non-transitory computer readable storage medium for storing computer instructions which, when executed by a processor, implement the supercapacitor-based grid-connected wind power generation low voltage ride through method of any one of claims 1 to 7.
10. An electronic device, comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the grid-connected wind power generation low voltage ride through method based on the super capacitor as claimed in any one of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311076811.5A CN117081155A (en) | 2023-08-24 | 2023-08-24 | Grid-connected wind power generation low-voltage ride through method and system based on super capacitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311076811.5A CN117081155A (en) | 2023-08-24 | 2023-08-24 | Grid-connected wind power generation low-voltage ride through method and system based on super capacitor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117081155A true CN117081155A (en) | 2023-11-17 |
Family
ID=88703881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311076811.5A Pending CN117081155A (en) | 2023-08-24 | 2023-08-24 | Grid-connected wind power generation low-voltage ride through method and system based on super capacitor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117081155A (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080136359A1 (en) * | 2006-11-15 | 2008-06-12 | Sung Jin Chung | Regenerative braking system of fuel cell vehicle using super capacitor |
| US20100001584A1 (en) * | 2008-05-29 | 2010-01-07 | Teknoware Oy | Method and arrangement in conjunction with emergency light |
| KR20120113340A (en) * | 2011-04-05 | 2012-10-15 | 주식회사 메가베스 | Device and method for low voltage ride through of wind generator |
| CN103875146A (en) * | 2011-09-14 | 2014-06-18 | 伊斯帕诺-絮扎公司 | Method and device for multi-user signal detection |
| US20190190274A1 (en) * | 2016-06-16 | 2019-06-20 | Swansea University | An energy management system and method for grid-connected and islanded micro-energy generation |
| CN212183138U (en) * | 2020-06-01 | 2020-12-18 | 哈尔滨理工大学 | Low pressure passes through device based on novel crowbar |
| CN115085270A (en) * | 2022-07-21 | 2022-09-20 | 山东大学 | Low-voltage ride through method and system for wind power converter |
| CN115085204A (en) * | 2022-07-21 | 2022-09-20 | 山东大学 | Unloading circuit, low-voltage ride-through control method and system |
| CN116231826A (en) * | 2023-04-13 | 2023-06-06 | 天津大学 | Hybrid energy storage system power distribution method based on dynamic virtual impedance network |
| CN116632991A (en) * | 2023-05-30 | 2023-08-22 | 西安合容新能源科技有限公司 | Distributed communication-free power coordination distribution system and method based on hybrid energy storage device |
-
2023
- 2023-08-24 CN CN202311076811.5A patent/CN117081155A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080136359A1 (en) * | 2006-11-15 | 2008-06-12 | Sung Jin Chung | Regenerative braking system of fuel cell vehicle using super capacitor |
| US20100001584A1 (en) * | 2008-05-29 | 2010-01-07 | Teknoware Oy | Method and arrangement in conjunction with emergency light |
| KR20120113340A (en) * | 2011-04-05 | 2012-10-15 | 주식회사 메가베스 | Device and method for low voltage ride through of wind generator |
| CN103875146A (en) * | 2011-09-14 | 2014-06-18 | 伊斯帕诺-絮扎公司 | Method and device for multi-user signal detection |
| US20190190274A1 (en) * | 2016-06-16 | 2019-06-20 | Swansea University | An energy management system and method for grid-connected and islanded micro-energy generation |
| CN212183138U (en) * | 2020-06-01 | 2020-12-18 | 哈尔滨理工大学 | Low pressure passes through device based on novel crowbar |
| CN115085270A (en) * | 2022-07-21 | 2022-09-20 | 山东大学 | Low-voltage ride through method and system for wind power converter |
| CN115085204A (en) * | 2022-07-21 | 2022-09-20 | 山东大学 | Unloading circuit, low-voltage ride-through control method and system |
| CN116231826A (en) * | 2023-04-13 | 2023-06-06 | 天津大学 | Hybrid energy storage system power distribution method based on dynamic virtual impedance network |
| CN116632991A (en) * | 2023-05-30 | 2023-08-22 | 西安合容新能源科技有限公司 | Distributed communication-free power coordination distribution system and method based on hybrid energy storage device |
Non-Patent Citations (2)
| Title |
|---|
| QI LIU: ""LVRT Control Strategy Based on Supercapacitor for Offshore DFIG Wind Farm with HVDC-Grid"", 《 2020 4TH INTERNATIONAL CONFERENCE ON HVDC (HVDC)》, 29 December 2020 (2020-12-29) * |
| 王雨欣: ""超级电容储能和卸荷电路协调控制的永磁同步风电机组低 电压穿越策略"", 《高压电器》, 16 April 2023 (2023-04-16), pages 176 - 183 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104113077B (en) | A kind of control method for coordinating of dual-feed asynchronous wind power generator high voltage crossing | |
| Howlader et al. | A comprehensive review of low voltage ride through capability strategies for the wind energy conversion systems | |
| CN103124077B (en) | Suppress the system and method for generating set subsynchronous resonance | |
| WO2012083963A1 (en) | A method of operating a wind turbine as well as a system suitable therefore | |
| CN108448607B (en) | Grid-connected and off-grid switching method and device for micro-grid battery energy storage system | |
| CN107482653A (en) | The direct current transportation Double-feed wind power power of the assembling unit fluctuates and fault control system and method | |
| CN101950973A (en) | Double-fed wind generating set control system and stable control method | |
| CN111431206B (en) | Collaborative fault ride-through method for large-scale doubly-fed wind farm through flexible direct current delivery | |
| CN115085270B (en) | Low-voltage ride through method and system for wind power converter | |
| Bouaziz et al. | Direct power control of grid-connected converters using sliding mode controller | |
| Musarrat et al. | A fractional order SMC approach to improve the reliability of wind energy systems during grid faults | |
| Chung | Voltage Enhancement on DFIG Based Wind Farm Terminal During Grid Faults. | |
| Nasiri et al. | Efficient low-voltage ride-through nonlinear backstepping control strategy for PMSG-based wind turbine during the grid faults | |
| Torres-Olguin et al. | Hybrid HVDC connection of large offshore wind farms to the AC grid | |
| Olloqui et al. | Modulated model predictive rotor current control (M 2 PC) of a DFIG driven by an indirect matrix converter with fixed switching frequency | |
| Shah et al. | Direct power control of grid-connected DFIG using variable gain super-twisting sliding mode controller for wind energy optimization | |
| Barambones et al. | An adaptive sliding mode control law for the power maximization of the wind turbine system | |
| Yu et al. | Internal model startup control for VSC-LCC based hybrid pseudo bipolar HVDC system | |
| CN117081155A (en) | Grid-connected wind power generation low-voltage ride through method and system based on super capacitor | |
| CN110943484B (en) | Double-fed fan based on unified power quality regulator and application method thereof | |
| Zoghlami et al. | Implementation of different strategies of direct power control | |
| Riouch et al. | Control of battery energy storage system for wind turbine based on DFIG during symmetrical grid fault | |
| Younesi et al. | Computationally efficient long horizon model predictive direct current control of DFIG wind turbines | |
| Kheibargir et al. | Augmentation of fault ride-through capability of PMSG in a wind power plant using resistive SFCL and a new reactive current injection controller | |
| CN111555296A (en) | Current converter control method for improving low voltage ride through capability of doubly-fed wind turbine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |