CN110224438B - Ride-through control method for offshore wind farm flexible direct-sending system under power grid fault - Google Patents
Ride-through control method for offshore wind farm flexible direct-sending system under power grid fault Download PDFInfo
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- 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
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- 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
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- H02J3/386—
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- 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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention discloses a ride-through control method of a soft direct-sending system of an offshore wind farm under a power grid fault, which is characterized by calculating the active power surplus P of the offshore wind farm when the direct-current voltage rises and is greater than or equal to the maximum allowable valueol(ii) a When P is presentol＞PtpmWhen the power consumption control is started, all the doubly-fed wind turbine generators in sub-synchronous operation are subjected to power consumption control, the power consumption control coefficient is set as the maximum power consumption control coefficient of the doubly-fed wind turbine generators in sub-synchronous operation in the offshore wind farm, and meanwhile, the doubly-fed wind turbine generators in super-synchronous operation are cut off; when P is presentol≤PtpmAnd when the wind power generation system runs, all the doubly-fed wind generation sets running in the sub-synchronous mode start energy consumption control, and then control is implemented. The method can give full play to the flexible power control capability of the double-fed wind turbine generator, quickly realize the active power balance of the offshore wind power plant flexible direct-output system, avoid flexible direct locking and wind power plant outage caused by power grid faults, and has the advantages of high control efficiency, small impact on the double-fed wind turbine generator and the flexible direct-output system, wide application range and the like.
Description
Technical Field
The invention relates to the field of protection and control of power systems, in particular to a crossing control method for a flexible direct-sending system of an offshore wind farm under a power grid fault.
Background
In order to solve the global energy crisis, wind power generation is rapidly developed in the global scope. Compared with the development of relatively complete land wind power, offshore wind power has a wider development prospect. Compared with an alternating current power transmission grid connection mode and a conventional direct current power transmission grid connection mode, the offshore wind power grid connection mode through the flexible direct power transmission system can isolate a wind power plant from an alternating current main grid, has black start capability, reduces reactive compensation devices, is suitable for transmission of long-distance wind power, and has become a main mode of offshore wind power grid connection at present.
In the offshore wind farm flexible direct-transmitting system, when a receiving-end power grid has a short-circuit fault, active power output by a receiving-end power grid side converter station of the flexible direct-transmitting system is reduced, active power generated by a double-fed wind turbine generator is determined by a control system of the double-fed wind turbine generator and basically keeps unchanged in a fault process, and unbalanced active power generated from the active power enables direct-current voltage of the flexible direct-transmitting system to be increased, and the direct-current voltage is out of limit, so that the flexible direct-transmitting system can be locked. Due to the large scale of the offshore wind farm, if the offshore wind farm is cut off from the power system, large active impact may be further caused to the system, and the stable operation of the power system is damaged. Under the condition of receiving end power grid failure, how to ensure the safety of the offshore wind farm and the flexible direct power transmission system and how to avoid the disconnection of the offshore wind farm and the flexible direct power transmission system, so that the passing through of the power grid failure stage becomes a key problem in the development and operation of the offshore wind farm.
At present, the main method for fault ride-through of the flexible direct-current sending system of the offshore wind farm is to install an additional energy-discharging resistor on a direct-current bus of the flexible direct-current sending system to avoid the direct-current voltage from exceeding the limit, but the heat dissipation problem of the energy-discharging resistor is serious, a large potential safety hazard exists, the fault ride-through requirement of the flexible direct-current sending system of the offshore wind farm cannot be met frequently, and the use of the additional energy-discharging resistor can obviously increase the investment cost.
The method is characterized in that a double-fed wind turbine generator is controlled to reduce active power by utilizing a fault signal of a wind power plant side converter station of a flexible direct-sending-out system, so that unbalanced active power of a source network is reduced, and the method gradually becomes an effective selection for fault ride-through of the flexible direct-sending-out system of the offshore wind power plant. The current major methods include class 2: up-conversion and down-conversion. The frequency boosting method takes frequency as a carrier, transmits direct-current overvoltage information to the wind power plant, and reduces the emitted active power through virtual inertia control of the wind power plant. However, the frequency-up method mainly determines the frequency adjustment amount from the viewpoint of active power balance of the soft direct-output system, and does not consider the influence of frequency change on the doubly-fed wind turbine generator. Due to the fact that the change of the generator terminal voltage frequency of the doubly-fed wind turbine generator affects the electromagnetic transient process of a rotor winding through the reaction of a generator stator and the current transformation control, the rotor current is increased possibly, and the safety of a converter of the doubly-fed wind turbine generator is threatened. The voltage reduction method directly reduces the alternating-current side voltage of the wind power plant side converter station of the flexible direct-output system, and the purpose of reducing active power is achieved. However, since the doubly-fed wind turbine generator is sensitive to the generator-side voltage, the step-down method may trigger the low-voltage ride-through control of the doubly-fed wind turbine generator. More importantly, the frequency-up method and the voltage-down method only enable the doubly-fed wind turbine generator to change within a small range of normal operating power, and the change range is usually far smaller than the power unbalance amount caused by the fault of a receiving-end power grid, so that the application range of the frequency-up method and the voltage-down method is limited, and the problem of fault ride-through of a flexible and direct sending-out system of an offshore wind farm cannot be thoroughly solved.
In summary, with the continuous increase of installed capacity of the offshore wind farm, due to the lack of a fault ride-through method of the flexible direct-sending system of the offshore wind farm, a power grid fault is easy to occur to cause the flexible direct-sending system to be locked, so that a large number of wind turbines are off-grid, a large active impact is caused to the power grid, the safe and stable operation of the whole system is threatened, and how to fully utilize the flexible power control capability of the double-fed wind turbine to more effectively realize the fault ride-through of the flexible direct-sending system of the offshore wind farm becomes a problem which needs to be solved by technical personnel in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a crossing control method for a soft direct-current discharging system of an offshore wind farm under the condition of power grid failure, which considers the switching of control modes of a receiving-end power grid-side converter station of the soft direct-current discharging system of the offshore wind farm when the power grid fails, considers the influence of active power balance of a source grid on direct-current voltage, and avoids soft direct locking and outage of the wind farm caused by the power grid failure. The control method can formulate a control and cutting scheme of the double-fed wind turbine generator according to the severity of the fault, fully exert the flexible power control capability of the double-fed wind turbine generator, realize the fault ride-through of the offshore wind turbine flexible direct-output system after the direct-current voltage of the power grid rises, and has the advantages of large control margin, simplicity in realization, high economy and the like.
In order to solve the technical problems, the invention adopts the following technical scheme:
a passing control method for a soft and direct sending system of an offshore wind farm under a power grid fault comprises the following steps:
s1, detecting the direct current voltage of the offshore wind farm flexible direct-sending system in real time;
s2, when the direct current voltage rises and is larger than or equal to the maximum allowable value, obtaining the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage rises, and calculating the active power surplus P of the offshore wind farm based on the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage risesol；
S3, when Pol＞PtpmAnd meanwhile, cutting off the doubly-fed wind turbine generator in super-synchronous operation, wherein the capacity of the cut-off generator is Pol-Ptpm，PtpmThe method comprises the steps that the maximum active power which can be reduced by adopting energy consumption control of an offshore wind power plant is represented, and a doubly-fed wind turbine generator in sub-synchronous operation and a doubly-fed wind turbine generator in super-synchronous operation are determined based on the rotating speed of the doubly-fed wind turbine generator;
s4, when Pol≤PtpmAnd meanwhile, all the doubly-fed wind power generation sets in sub-synchronous operation start energy consumption control, and the energy consumption control coefficient is determined based on the proportion of the maximum power which can be consumed when each doubly-fed wind power generation set in sub-synchronous operation adopts energy consumption control.
Preferably, the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed in energy consumption control are obtained, and the maximum active power P which can be reduced in the offshore wind power plant in energy consumption control is calculated based on the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed in energy consumption controltpmAnd determining the maximum energy consumption control coefficient of the doubly-fed wind turbine generator which operates in the sub-synchronous mode in the offshore wind farm based on the safety constraint condition of the doubly-fed wind turbine generator.
Preferably, the offshore wind farm uses the maximum active power P that can be reduced by energy consumption controltpmCalculated based on the following formula:
in the formula, m is the number of the double-fed wind turbine generators in the sub-synchronous operation of the offshore wind farm,
and
the output power of the j sub-synchronous operation doubly-fed wind turbine generator and the maximum power which can be consumed when energy consumption control is adopted are respectively set;
output power of jth sub-synchronous running doubly-fed wind turbine generator
Obtained by an on-line monitoring system, and the maximum power which can be consumed when the energy consumption control is adopted
Calculated by the following formula:
in the formula, LmAnd LsThe excitation inductance and the stator inductance of the double-fed wind turbine generator are respectively;
the terminal voltage of the jth sub-synchronous running doubly-fed wind turbine generator is obtained; omegasThe synchronous angular speed of the doubly-fed wind turbine generator is obtained;
and the maximum energy consumption control coefficient is the maximum energy consumption control coefficient of the jth sub-synchronous operation doubly-fed wind turbine generator.
Preferably, the active power surplus P of the offshore wind farmolCalculated based on the following formula:
Pol＝Pgs0-Pgsf
in the formula, Pgs0Before the direct-current voltage rises, flexibly and directly sending out the output power of a converter station at the receiving end power grid side of the system from the offshore wind farm; pgsfThe output power of the converter station at the receiving end power grid side of the system is flexibly and directly sent out after the direct-current voltage is increased;
in the formula of UgsfObtaining the alternating-current voltage amplitude of the receiving-end power grid side converter station after the direct-current voltage is increased through an online monitoring system; i isgsmIs the current limit value controlled by the current limit of the converter station at the receiving end power grid side.
Preferably, when P isol≤PtpmAnd meanwhile, the energy consumption of the j-th doubly-fed wind turbine generator in sub-synchronous operation is as follows:
the energy consumption control coefficient of the jth sub-synchronous operation doubly-fed wind turbine generator is as follows:
in summary, according to the method for controlling the crossing of the offshore wind farm flexible direct-output system under the power grid fault, the power imbalance of the offshore wind farm flexible direct-output system is realized through the active energy consumption of the double-fed wind turbine generator set according to the active power surplus of the offshore wind farm after the direct-current voltage of the power grid rises, so that the direct-current voltage fluctuation of the flexible direct-output system is stabilized, and flexible direct locking and outage of the wind farm caused by the power grid fault are avoided. Compared with the prior art, the method realizes the switching between the power generation running state and the electric running state of the offshore wind farm, fully exerts the flexible power control capability of the double-fed wind turbine generator, realizes the fault ride-through of the flexible direct-sending system of the offshore wind farm, and has the advantages of large regulation range, easy realization, wide application range and the like.
Drawings
For purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made in detail to the present invention as illustrated in the accompanying drawings, in which:
FIG. 1 is a flow chart of a method for controlling the passing through of a soft and direct wind farm out of a system in an offshore wind farm under a power grid fault, according to the present invention;
FIG. 2 is a schematic view of the flexible direct-delivery system of the offshore wind farm disclosed by the present invention;
fig. 3 is a block diagram of energy consumption control of the doubly-fed wind turbine.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, the invention discloses a passing control method for a soft direct-sending system of an offshore wind farm under a power grid fault, which comprises the following steps:
s1, detecting the direct current voltage of the offshore wind farm flexible direct-sending system in real time;
s2, when the direct current voltage rises and is larger than or equal to the maximum allowable value, obtaining the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage rises, and calculating the active power surplus P of the offshore wind farm based on the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage risesol；
S3, when Pol＞PtpmAnd meanwhile, cutting off the doubly-fed wind turbine generator in super-synchronous operation, wherein the capacity of the cut-off generator is Pol-Ptpm，PtpmThe method comprises the steps that the maximum active power which can be reduced by adopting energy consumption control of an offshore wind power plant is represented, and a doubly-fed wind turbine generator in sub-synchronous operation and a doubly-fed wind turbine generator in super-synchronous operation are determined based on the rotating speed of the doubly-fed wind turbine generator;
s4, when Pol≤PtpmAnd meanwhile, all the doubly-fed wind power generation sets in sub-synchronous operation start energy consumption control, and the energy consumption control coefficient is determined based on the proportion of the maximum power which can be consumed when each doubly-fed wind power generation set in sub-synchronous operation adopts energy consumption control.
In the invention, the maximum allowable value can be set according to the actual condition of the wind power plant, and when the direct current voltage rises and is greater than or equal to the maximum allowable value, the fault can be considered to occur. The determination that the doubly-fed wind turbine generator is a doubly-fed wind turbine generator in sub-synchronous operation or a doubly-fed wind turbine generator in super-synchronous operation based on the revolution number is prior art and is not repeated herein.
The method is characterized in that the energy consumption control coefficient of the doubly-fed wind turbine generator in sub-synchronous operation and the machine switching amount of the doubly-fed wind turbine generator in super-synchronous operation are determined according to the relation between the surplus active power of the offshore wind turbine generator and the maximum active power reduction amount of the offshore wind turbine generator adopting energy consumption control, the doubly-fed wind turbine generator is guaranteed not to run off the grid as far as possible, power self-balance is achieved by means of the rapid power control capacity of the doubly-fed wind turbine generator, and fault ride-through of a flexible direct-sending-out system is achieved. The method considers the switching of the control modes of the converter station at the receiving end power grid side of the flexible direct-transmission system during the power grid fault, considers the influence of the active power balance of the source power grid on the direct-current voltage, and avoids flexible direct locking and wind farm outage caused by the power grid fault. Compared with the prior art, the method realizes the switching between the power generation running state and the electric running state of the offshore wind farm, fully exerts the flexible power control capability of the double-fed wind turbine generator, realizes the fault ride-through of the flexible direct-sending system of the offshore wind farm, and has the advantages of large regulation range, easy realization, wide application range and the like.
In specific implementation, the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed in energy consumption control are obtained, and the maximum active power P which can be reduced in the offshore wind power plant in energy consumption control is calculated based on the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed in energy consumption controltpmAnd determining the maximum energy consumption control coefficient of the doubly-fed wind turbine generator which operates in the sub-synchronous mode in the offshore wind farm based on the safety constraint condition of the doubly-fed wind turbine generator.
In specific implementation, the maximum active power P which can be reduced by adopting energy consumption control in the offshore wind farmtpmCalculated based on the following formula:
in the formula, m is the number of the double-fed wind turbine generators in the sub-synchronous operation of the offshore wind farm,
and
the output power of the j sub-synchronous operation doubly-fed wind turbine generator and the maximum power which can be consumed when energy consumption control is adopted are respectively set;
output power of jth sub-synchronous running doubly-fed wind turbine generator
Obtained by an on-line monitoring system, and the maximum power which can be consumed when the energy consumption control is adopted
Calculated by the following formula:
in the formula, LmAnd LsThe excitation inductance and the stator inductance of the double-fed wind turbine generator are respectively;
the terminal voltage of the jth sub-synchronous running doubly-fed wind turbine generator is obtained; omegasThe synchronous angular speed of the doubly-fed wind turbine generator is obtained;
maximum of doubly-fed wind turbine generator set running in sub-synchronous mode for jth stationAnd (4) energy consumption control coefficient.
In specific implementation, the active power surplus P of the offshore wind power plantolCalculated based on the following formula:
Pol＝Pgs0-Pgsf
in the formula, Pgs0Before the direct-current voltage rises, flexibly and directly sending out the output power of a converter station at the receiving end power grid side of the system from the offshore wind farm; pgsfFor the output power of the converter station at the receiving end power grid side of the flexible direct-current sending-out system after the direct-current voltage is increased, considering that the converter station at the receiving end power grid side of the flexible direct-current sending-out system adopts a power grid voltage directional control mode, the converter station operates with a unit power factor during normal operation, and switches from constant direct-current voltage control to current limiting control during fault, so that:
in the formula of UgsfObtaining the alternating-current voltage amplitude of the receiving-end power grid side converter station after the direct-current voltage is increased through an online monitoring system; i isgsmIs the current limit value controlled by the current limit of the converter station at the receiving end power grid side.
When embodied, P isol≤PtpmAnd meanwhile, the energy consumption of the j-th doubly-fed wind turbine generator in sub-synchronous operation is as follows:
the energy consumption control coefficient of the jth sub-synchronous operation doubly-fed wind turbine generator is as follows:
the invention relates to a method for controlling the crossing of a soft direct-sending system of an offshore wind farm under the condition of power grid failure, which can formulate a control and tripping scheme of a double-fed wind turbine generator according to the severity of the failure, consider the switching of control modes of a receiving-end power grid side converter station of the soft direct-sending system during the power grid failure and the influence of active power balance of an active power grid on direct current voltage. The application of the present invention will be described below by taking the flexible direct-sending system of the offshore wind farm shown in fig. 2 as an example.
In fig. 2, an offshore wind farm, a flexible direct-output system, and a receiving-end power grid are sequentially arranged from left to right. PwfActive power, P, absorbed by the offshore wind farm side converter station for the flexible direct discharge systemgsActive power U generated by receiving-end power grid side converter station of flexible direct-transmission systemdcIs the direct current voltage of the flexible transmission system. When the offshore wind farm flexible direct-output system shown in fig. 2 has a fault in a receiving-end power grid, unbalanced active power at two ends of the flexible direct-output system will cause a rise in direct-current voltage, and the method of the present invention can be used for control in order to ensure the safety of the flexible direct-output system and the stable operation of a power system.
The energy consumption control block diagram of the doubly-fed wind turbine generator is shown in the attached figure 3, the rotor-side converter locks the outer ring controller, and d and q axis component reference values of rotor current of the inner ring controller are directly given
And
respectively 0, since the inner loop controller is generally designed according to a typical I-type system, the response speed, i, of millisecond grade can be realizedrdAnd irqThe d and q axis components of the rotor current, respectively. And after the energy consumption control coefficient of the doubly-fed wind turbine generator in the sub-synchronous operation is determined, inputting the energy consumption control coefficient into a rotor side converter of each doubly-fed wind turbine generator, and starting the energy consumption operation. OmegasAnd ωpSynchronous and slip angular velocities, R, respectivelyrIs rotor resistance, σ is magnetic leakage coefficient, LrAs an inductance of the rotor, there is a high inductance,
and
reference values for the d and q-axis components of the rotor voltage, respectively. The grid-side converter is designed by adopting a double-ring controller and is used for controlling direct-current voltage and stabilizing terminal voltage. U shapegAnd UdcThe magnitudes of the terminal voltage and the dc voltage respectively,
and
respectively the amplitude reference values of the terminal voltage and the direct-current voltage,
and
reference values i of d and q axis components of current of grid-side convertergdAnd igqRespectively d-and q-axis components of the grid-side converter current,
and
reference values of d-axis components and q-axis components of terminal voltage are respectively.
When the flexible direct-current output system of the offshore wind power plant breaks down, the current control method is limited by the operating conditions of the double-fed wind turbine generator, the adjusting range is limited, and the change of the direct-current voltage of the flexible direct-current output system cannot be completely stabilized. The method fully considers the switching of the control modes of the receiving-end power grid side converter station of the flexible direct-output system when the power grid fails, considers the influence of active power balance of the source grid on direct-current voltage, adopts a corresponding double-fed wind turbine power control means according to the active power surplus of the offshore wind farm after the direct-current voltage of the power grid rises, provides a calculation method for a control reference value and an improved control structure of the double-fed wind turbine, can fully exert the flexible power control capability of the double-fed wind turbine, quickly realizes the active power balance of the flexible direct-output system of the offshore wind turbine, avoids flexible direct locking and wind turbine stop caused by the power grid failure, and has the advantages of high control efficiency, small impact on the double-fed wind turbine and the flexible direct-output system, wide application range and the like.
Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, while the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (3)
1. A passing control method for a soft and direct sending system of an offshore wind farm under the condition of power grid failure is characterized by comprising the following steps:
s1, detecting the direct current voltage of the offshore wind farm flexible direct-sending system in real time;
s2, when the direct current voltage rises and is larger than or equal to the maximum allowable value, obtaining the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage rises, and calculating the active power surplus P of the offshore wind farm based on the output power of the receiving end power grid side converter station of the offshore wind farm flexible direct sending-out system before and after the direct current voltage risesolActive power surplus P of offshore wind farmolCalculated based on the following formula:
Pol＝Pgs0-Pgsf
in the formula, Pgs0Before the direct-current voltage rises, flexibly and directly sending out the output power of a converter station at the receiving end power grid side of the system from the offshore wind farm; pgsfThe output power of the converter station at the receiving end power grid side of the system is flexibly and directly sent out after the direct-current voltage is increased;
in the formula of UgsfObtaining the alternating-current voltage amplitude of the receiving-end power grid side converter station after the direct-current voltage is increased through an online monitoring system; i isgsmThe current limit value is controlled by the current limit of the converter station at the receiving end power grid side;
s3, obtaining the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed during energy consumption control, and calculating the maximum active power P which can be reduced by the offshore wind power plant through energy consumption control based on the output power of the sub-synchronous operation double-fed wind turbine generator and the maximum power which can be consumed during energy consumption controltpmDetermining the maximum energy consumption control coefficient of the doubly-fed wind turbine generator which operates in sub-synchronous mode in the offshore wind farm based on the safety constraint condition of the doubly-fed wind turbine generator, and when P is the maximum energy consumption control coefficientol＞PtpmAnd meanwhile, cutting off the doubly-fed wind turbine generator in super-synchronous operation, wherein the capacity of the cut-off generator is Pol-PtpmThe method comprises the following steps that a sub-synchronous running double-fed wind turbine generator and a super-synchronous running double-fed wind turbine generator are determined based on the rotating speed of the double-fed wind turbine generator;
s4, when Pol≤PtpmAnd meanwhile, all the doubly-fed wind power generation sets in sub-synchronous operation start energy consumption control, and the energy consumption control coefficient is determined based on the proportion of the maximum power which can be consumed when each doubly-fed wind power generation set in sub-synchronous operation adopts energy consumption control.
2. The grid-fault soft direct-sending system ride-through control method of offshore wind farms according to claim 1, wherein the offshore wind farms adopt energy consumption to control the maximum active power P which can be reducedtpmCalculated based on the following formula:
in the formula, m is the number of the double-fed wind turbine generators in the sub-synchronous operation of the offshore wind farm,
and
the output power of the j sub-synchronous operation doubly-fed wind turbine generator and the maximum power which can be consumed when energy consumption control is adopted are respectively set;
output power of jth sub-synchronous running doubly-fed wind turbine generator
Obtained by an on-line monitoring system, and the maximum power which can be consumed when the energy consumption control is adopted
Calculated by the following formula:
in the formula, LmAnd LsThe excitation inductance and the stator inductance of the double-fed wind turbine generator are respectively;
the terminal voltage of the jth sub-synchronous running doubly-fed wind turbine generator is obtained; omegasThe synchronous angular speed of the doubly-fed wind turbine generator is obtained;
and the maximum energy consumption control coefficient is the maximum energy consumption control coefficient of the jth sub-synchronous operation doubly-fed wind turbine generator.
3. The method for grid fault offshore wind farm flexible direct-out system ride-through control as claimed in claim 1, wherein P is Pol≤PtpmWhen, the jth station isThe energy consumption of the doubly-fed wind turbine generator which operates synchronously is as follows:
the energy consumption control coefficient of the jth sub-synchronous operation doubly-fed wind turbine generator is as follows:
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| CN111668871B (en) * | 2020-06-18 | 2022-04-22 | 北京四方继保自动化股份有限公司 | AC fault ride-through control method under new energy access flexible DC distribution network system |
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