CN113315136A - Power control method and system for fault ride-through of double-fed asynchronous fan - Google Patents

Power control method and system for fault ride-through of double-fed asynchronous fan Download PDF

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CN113315136A
CN113315136A CN202110421036.7A CN202110421036A CN113315136A CN 113315136 A CN113315136 A CN 113315136A CN 202110421036 A CN202110421036 A CN 202110421036A CN 113315136 A CN113315136 A CN 113315136A
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voltage
ref
reference value
power
reactive
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杨蕾
何金定
蔡光
剡文林
黄润
张斌
秦文超
张哲铭
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Yunnan Power Grid Co Ltd
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Yunnan Power Grid Co Ltd
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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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • 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
    • 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
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/007—Control circuits for doubly fed generators
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Abstract

The invention relates to a power control method and a system for low voltage ride through of a double-fed asynchronous fan, which comprises the steps of monitoring a voltage effective value of a grid-connected point of the double-fed asynchronous fan in real time, and calculating a voltage deviation value of the voltage effective value of the grid-connected point and a voltage reference value; judging whether the voltage of the power grid drops or rises or not according to the range of the voltage deviation value; calculating a reactive reference value according to whether the obtained power grid voltage drops or rises; calculating an active reference value according to the reactive reference value and the maximum power tracking power; and receiving the active reference value and the reactive reference value so as to realize the control of the fan. According to the method, the reactive power reference value which can be provided currently is obtained through PI control according to the real-time deviation of the real-time voltage measured value and the voltage dead zone value, and reactive support is carried out when the voltage of the power grid drops. The method reduces the loss degree of hardware facilities, prolongs the service life of the facilities, reduces the system cost and improves the electric energy conversion efficiency of the system.

Description

Power control method and system for fault ride-through of double-fed asynchronous fan
Technical Field
The invention belongs to the technical field of grid-connected control systems for wind power generation systems, and particularly relates to a power control method and system for low-voltage ride through of a double-fed asynchronous fan.
Background
With the large-scale grid connection of wind power, negative effects are brought to the voltage and frequency stability of a power grid system while the energy crisis is relieved. The fault ride-through problem is a common problem generally caused by large-amount deviation between a power grid transmission section and a receiving end or line faults, a wind turbine generator is very sensitive to the voltage change of a grid-connected point due to a converter consisting of power electronic devices in the structure of the wind turbine generator, and when the voltage of the grid-connected point drops, the operation stability of a fan is influenced by unbalanced mechanical power and electromagnetic power, so that the devices can be damaged due to overcurrent and additional torque generated by the influence. In addition, a short-time fault of the power grid may cause the wind turbine to be disconnected, and the disconnection of the wind turbine may cause the change of power distribution and the stability problem of the whole system.
At present, the LVRT function of new energy is more to keep new energy from taking off machine work, and there are generally two methods, namely a bypass protection strategy and an excitation control strategy, in the former, the overcurrent problem caused by LVRT is mainly suppressed by improving a Crowbar circuit, but a Double-fed-induction wind generator (DFIG) is usually caused to absorb reactive power of a power grid, and is not beneficial to fault node voltage recovery; the control mode of a Rotor-side converter (RSC) and a Grid-side converter (GSC) of the DFIG is mainly changed, so that the damage caused by over current can be reduced, and reactive power absorption of the DFIG to a power Grid can be inhibited. However, the DFIG cannot transmit reactive power to the power grid in the low-voltage ride-through process, the DFIG can instantaneously provide a large amount of reactive support for the power grid in the fault ride-through process of the power grid, and large-amplitude fluctuation of reactive power of a system level is caused, the fluctuation can cause short-time large-amplitude fluctuation of the reactive power of the power grid in a system operated by high-proportion new energy, the power grid is not favorable for stability of the power grid, and the overvoltage problem of the power grid can be aggravated in the processes of direct-current commutation failure and the like for a system with bundled wind power. Therefore, how to overcome the defects of the prior art is a problem which needs to be solved in the technical field of the grid-connected control system of the wind power generation system at present.
Disclosure of Invention
The invention provides a power control method and a system for doubly-fed asynchronous fan fault ride-through, aiming at solving the problems of transient impact and energy loss generated by instantaneous switching of a network side converter control mode and a rotor side converter control mode and the re-investment of the rotor side converter in the voltage recovery stage in the fault ride-through process. The control method can reduce the loss degree of hardware facilities, prolong the service life of the facilities, reduce the system cost and improve the electric energy conversion efficiency of the system and the voltage and frequency stability of the system.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a double-fed asynchronous fan fault ride-through power control method comprises the following steps:
step (1), monitoring the effective value U of the voltage of the grid-connected point of the doubly-fed fan in real timerms_measAnd calculating the effective value U of the voltage of the grid-connected pointrms_measAnd a voltage reference value UrefVoltage deviation value Δ U;
step (2), judging whether the power grid voltage falls or rises according to the range of the deviation value delta U;
step (3), when no voltage drop exists, the voltage deviation signal is subjected to dead zone control and then subjected to PI control, and then the reactive power reference value is 0; when the voltage drops or rises, the voltage deviation value delta U crosses the dead zone control, and after PI control, the reactive reference value Q is obtainedrefStarting to change, and starting to output reactive power by the fan;
step (4), the active reference value is obtained according to the reactive reference value and the maximum power tracking power P obtained in the step (3)mpptBy the formula
Figure BDA0003027842920000021
Calculating to obtain;
and (5) transmitting the obtained active reference value and reactive reference value signals to a rotor side and network side variable flow control system, thereby realizing the control of the fan.
Further, it is preferable that the specific method of the step (2) is: if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]Within the range, judging that the voltage of a grid connection point is too low, and cutting off the unit; if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefAnd in the above process, judging that the voltage of the grid-connected point is too high, and cutting off the unit.
Further, it is preferable that the specific method of step (4) is:
if the voltage has no drop, the reactive reference value is 0, and the active reference value Pref＝Pmppt(ii) a If the voltage rises, the reactive power and the active power of the power grid are absorbedReference value Pref＝Pmppt(ii) a If the voltage drops, the reactive reference value begins to change, and the active reference value is based on
Figure BDA0003027842920000031
And reducing to meet the reactive output requirement of the fan.
The invention also provides a power control system for doubly-fed asynchronous fan fault ride-through, which comprises:
the voltage real-time monitoring module is used for monitoring the effective value U of the voltage of the grid-connected point of the double-fed fan in real timerms_measAnd calculating the effective value U of the voltage of the grid-connected pointrms_measAnd a voltage reference value UrefVoltage deviation value Δ U;
the voltage deviation dead zone control module is used for judging whether the power grid voltage drops or rises or not according to the range of the voltage deviation value delta U;
the reactive reference value calculating module is used for calculating a reactive reference value according to whether the obtained power grid voltage falls or rises;
an active reference value calculation module for tracking power P according to the reactive reference value and the maximum powermpptCalculating an active reference value;
and the rotor side and network side variable flow control systems are used for receiving the active reference value and the reactive reference value so as to realize the control of the fan.
Further, preferably, the method for determining whether the grid voltage drops is as follows: if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]And in the range, judging that the voltage of the grid connection point is too low, and cutting off the unit.
Further, preferably, the method for determining whether the grid voltage is increased is as follows: if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefIn the above, the grid connection is judgedAnd (4) cutting off the unit when the point voltage is too high.
Compared with the prior art, the invention has the beneficial effects that:
1. by means of the operation strategy of the rotor-side and grid-side converters when a fault occurs, the double-fed fan can transmit certain reactive power to a fault node when the voltage of a power grid is too low; when the voltage of the power grid is too high, certain reactive power is absorbed to the system, the power change is relatively smooth, and the smooth degree can be adjusted through parameter setting and optimization. And the power fluctuation and coupling of the power grid caused by fault ride-through are effectively inhibited.
2. The method is used for obtaining smooth reactive power reference values and active power reference values under a reactive power priority control mode by monitoring the voltage of a real-time grid-connected point, performing deviation calculation on the voltage reference values and performing voltage PI control, and solves the problems of transient impact and energy loss caused by switching of a grid-side converter control mode and a rotor-side converter control mode and the re-investment of the rotor-side converter in the voltage recovery stage in the fault ride-through process instead of the conventional step-type reference value change for determining reactive power and active power control.
3. The method realizes smooth support of reactive power in the voltage fluctuation or fault ride-through process of the power grid, avoids large fluctuation of the voltage of the power grid or large fluctuation of the reactive power and the active power in the fault ride-through process, is favorable for stabilizing the voltage and the frequency of the power grid, and effectively ensures the stable operation of the power grid particularly for an asynchronous low-inertia power system.
Drawings
FIG. 1 is a schematic flow chart of a power control method for doubly-fed asynchronous fan fault ride-through according to the present invention;
fig. 2 is an explanatory diagram of a corresponding relationship between the rotor speed and the output active power of the doubly-fed wind turbine;
FIG. 3 is a schematic diagram of a fault ride-through controller;
fig. 4 is a schematic diagram illustrating the architecture of the grid-side converter control system;
FIG. 5 is a schematic illustration of a rotor-side converter control system architecture;
FIG. 6 is a diagram of a conventional constant reactive power control;
FIG. 7 is a diagram illustrating reactive power control with an additional voltage PI control link in an embodiment;
FIG. 8 is a cross-point voltage of an embodiment;
FIG. 9 is an active and reactive curve of a fan during a fault under constant and reactive power control; wherein, (a) is an active curve of the fan during the fault period under the constant reactive power control; (b) a reactive curve of the fan during the fault period under the constant reactive control is obtained;
FIG. 10 is an active and reactive curve of a wind turbine during a fault under an embodiment control method; wherein, (a) is an active curve of the fan during the fault period under the control method of the embodiment; (b) the reactive curve of the fan during the fault period under the control method of the embodiment is shown;
fig. 11 is a schematic structural diagram of a doubly-fed asynchronous wind turbine fault ride-through power control system according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples.
It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.
As shown in fig. 1, a method for controlling power of doubly-fed asynchronous wind turbine fault ride-through includes the following steps:
detection double-fed fan grid-connected point voltage effective value Urms_measAnd according to the voltage reference value UrefAnd net point voltage effective value Urms_measObtaining a reactive reference value Q in the fault ride-through process through PI controlrefActive reference value Pref。
Setting a dead zone range (deviation value is less than or equal to 0.1U)ref) And judging whether the voltage of the power grid drops or rises.
If the voltage of the grid-connected point falls, namely the voltage deviation crosses the dead zone, the fan enters a fault ride-through state, reactive and active reference values of reactive control are changed through the voltage deviation, at the moment, a reactive control mode is equivalent to the situation that constant reactive power is changed into variable reactive power, the Q-axis current of the rotor-side converter is increased, and the reactive power output by the double-fed fan is increased.
For ensuring reactive output, the active reference value passes through the reactive reference value QrefAnd formula
Figure BDA0003027842920000051
To correct it.
And the given value of the constant reactive current control of the control network side variable converter is obtained by calculating the voltage deviation value delta U through a PI control link. And the rotor-side converter is switched from the steady-state maximum active power tracking control to the fault ride-through reactive power control. After the fault ride-through reactive power control is started, a reactive target value (namely a reactive reference value) is calculated through calculating a voltage deviation value delta U and through PI control and is used as a target value of the constant reactive power control. And Q-axis currents of the grid-side converter and the rotor-side converter are increased, so that the reactive power output by the double-fed fan is increased. Because the target value of the reactive power control is changed only through the voltage deviation value delta U, the target value can realize smooth regulation output of the reactive power through a PI link of the constant reactive power control, and reactive power step change caused by directly switching a constant reactive power (constant reactive current control) mode to constant transient alternating voltage control is avoided, so that systematic reactive power is caused to fluctuate greatly.
If the voltage is not dropped, namely the voltage deviation is in the dead zone range, the voltage deviation value is subjected to a dead zone judgment link and a PI link to obtain a reactive reference value QrefIs 0, the reactive control mode at the moment is equivalent to constant reactive control, and meanwhile, the active reference value of the fan is based on the reactive reference value QrefAnd formula
Figure BDA0003027842920000052
Obtaining Pref＝PmpptThe active reference value follows the maximum power point tracking control. If the voltage rises, the reactive power of the power grid is absorbed, and the active reference value Pref＝Pmppt. If the voltage drops, the reactive reference value startsChange when the active reference value is in accordance with
Figure BDA0003027842920000061
And reducing to meet the reactive output requirement of the fan.
The reactive reference value can realize smooth regulation output of reactive power through a dead zone control link and a PI control link of reactive control, and reactive power step-type change caused by direct switching of a constant reactive power (constant reactive current control) mode to constant transient alternating voltage control is avoided, so that systematic reactive power is caused to fluctuate greatly.
As shown in fig. 11, the power control system for doubly-fed asynchronous wind turbine fault ride-through includes:
the voltage real-time monitoring module 101 is used for monitoring the effective voltage value U of the grid-connected point of the doubly-fed fan in real timerms_measAnd calculating the effective value U of the voltage of the grid-connected pointrms_measAnd a voltage reference value UrefVoltage deviation value Δ U;
the voltage deviation dead zone control module 102 is used for judging whether the power grid voltage drops or rises according to the range of the voltage deviation value delta U;
specifically, the method comprises the following steps:
the method for judging whether the voltage of the power grid drops comprises the following steps: if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]And in the range, judging that the voltage of the grid connection point is too low, and cutting off the unit.
The method for judging whether the voltage of the power grid is increased is as follows: if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefAnd in the above process, judging that the voltage of the grid-connected point is too high, and cutting off the unit.
A reactive reference value calculation module 103, configured to calculate a reactive reference value according to whether the obtained grid voltage drops or rises;
the method specifically comprises the following steps: the voltage deviation value is given in real time, when no voltage drops, the reactive power reference value is 0 after the voltage deviation signal is subjected to dead zone control and PI control, and the value is equivalent to constant reactive power; when the voltage drops or rises, the voltage deviation value delta U crosses the dead zone control, and after PI control, the reactive reference value Q is obtainedrefStarting to change, and starting to output reactive power by the fan;
an active reference value calculation module 104 for tracking the power P according to the reactive reference value and the maximum powermpptCalculating an active reference value;
the method specifically comprises the following steps:
if the voltage has no drop, the reactive reference value is 0, and the active reference value Pref＝Pmppt(ii) a If the voltage rises, the reactive power of the power grid is absorbed, and the active reference value Pref＝Pmppt(ii) a If the voltage drops, the reactive reference value begins to change, and the active reference value is based on
Figure BDA0003027842920000071
And reducing to meet the reactive output requirement of the fan.
And the rotor side and network side variable flow control system 105 is used for receiving the output active reference value and the output reactive reference value so as to realize control on the fan.
In FIG. 3, the effective value U of the voltage of the grid-connected point is measured in real timerms_measAnd a voltage reference value UrefPerforming real-time deviation calculation to obtain a real-time voltage deviation value delta U as a determination condition of the dead zone determination link in FIG. 3, if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]Within the range, the grid-connected point is judged to have too low voltage, and the unit can be cut off; if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefIn the above, the grid-connected point is judged to be over high voltage, and the unit can be cut off.
Generally, it can be known that a wind turbine generally operates in a maximum power control mode, and fig. 2 is a corresponding relationship between a rotor speed of a doubly-fed wind turbine and a maximum output power. The converter between the fan and the power grid can realize the power transmission of the wind turbine generator to the power grid, so that the power factor of wind power can be changed through the converter to carry out reactive power support on the power grid, meanwhile, the active and reactive outputs of the fan are limited by the capacity of the fan, the maximum power P is obtained through real-time monitoring of the wind speed and the rotating speed of a rotor and an mppt maximum power tracking curvemppt. From the grid-connected voltage measurement Urms_measAnd a voltage reference value UrefThe voltage deviation value delta U is subjected to PI control link to obtain a reactive reference value QrefBack pass
Figure BDA0003027842920000072
Calculating to obtain an active reference value Pref。
In this example, the grid-side converter control structure is shown in fig. 4, and the grid-side converter is connected to Udc_refAnd Udc_measSubtracting and obtaining i through PI controlgd_ref，igq_refSet to a constant 0, igd_refAnd igq_refAre respectively connected with igdAnd igqSubtracting and obtaining V through inner ring PI controlgd_refAnd Vgq_refFor DQ axis voltage reference value, V is obtained by conversion from DQ coordinate system to abc coordinate systemgabcFor generating the trigger pulse.
Rotor-side converter control structure as shown in FIG. 5, the rotor-side converter converts PrefAnd PmeasSubtracting and obtaining i through PI controlrd_ref，QrefAnd QmeasSubtracting and obtaining i through PI controlrq_ref。ird_refAnd irq_refAre respectively connected with igdAnd igqSubtracting and obtaining u through inner loop PI controlrd_refAnd urq_refFor DQ axis voltage reference value, u is obtained by conversion from DQ coordinate system to abc coordinate systemrabcFor generating the trigger pulse.
A common constant reactive power control structure is shown in FIG. 6, wherein a grid-side converter converts QsrefIs subtracted from Qs and is subjected toOver PI control to obtain igd_ref，igq_refSet to a constant 0, igd_refAnd igq_refAre respectively connected with igdAnd igqSubtracting and obtaining V through inner ring PI controlgd_refAnd Vgq_refFor DQ axis voltage reference value, V is obtained by conversion from DQ coordinate system to abc coordinate systemgabcFor generating the trigger pulse.
In this example, the constant-reactive power control with the voltage PI control link added is shown in fig. 7, and the grid-side converter converts U tosd_refAnd UsdSubtracting and obtaining Qs through PI controlrefWill be QsrefSubtracting Qs and obtaining i through PI controlgd_refMeanwhile, the active and reactive outputs of the fan are limited by the capacity of the fan, the maximum power P is obtained through real-time monitoring of the wind speed and the rotor speed and an mppt maximum power tracking curvemppt. From the grid-connected voltage measurement Urms_measAnd a voltage reference value UrefThe deviation value is subjected to PI control link to obtain a reactive reference value QrefBack pass
Figure BDA0003027842920000081
Calculating to obtain an active reference value PrefFurther obtaining i through PI controlgq_ref，igd_refAnd igq_refAre respectively connected with igdAnd igqSubtracting and obtaining V through inner ring PI controlgd_refAnd Vgq_refFor DQ axis voltage reference value, V is obtained by conversion from DQ coordinate system to abc coordinate systemgabcFor generating the trigger pulse.
According to the method for controlling the fault ride-through of the double-fed fan, when a power grid fails, the voltage deviation of a grid-connected point exceeds a dead zone range, the grid-side converter and the rotor-side converter are controlled by the steady-state maximum power tracking to smoothly convert the fault ride-through reactive power control, the double-fed fan outputs or absorbs certain reactive power to support the system voltage, and the system voltage is recovered. And when the voltage deviation of the grid-connected point returns to the dead zone range after the voltage recovery, the control mode is switched back to the normal control.
This example verifies the method in a simulation system such as that of FIGS. 6-10
Step S1: real-time detection fan grid-connected point Urms_measAnd calculating the voltage deviation delta U in real time.
Step S2: and judging whether the voltage deviation is in a dead zone, expressing the voltage drop or rise degree by the voltage deviation, judging that the voltage fluctuation degree is not large when the voltage deviation is in the dead zone, judging that the system has no fault, and judging that the voltage deviation exceeds the dead zone, expressing that the voltage fluctuation degree is overlarge and judging that the system has a fault. The specific method comprises the following steps: if the voltage deviation value deltau is within the predetermined range,f[-0.1Ure，0]within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]Within the range, the grid-connected point is judged to have too low voltage, and the unit can be cut off; if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefIn the above, the grid-connected point is judged to be over high voltage, and the unit can be cut off.
Step 3, setting a reactive reference value according to the voltage deviation, wherein the reactive reference value Q is obtained when the voltage deviation is in a dead zonerefIs 0. When the voltage deviation crosses the dead zone, the reactive active reference value begins to change along with the voltage drop degree.
And 4, calculating an active reference value according to the reactive reference value.
And 5, transmitting the obtained active reference value and reactive reference value signals to a rotor side and network side variable flow control system, thereby realizing the control of the fan.
Simulation verification:
a simulation model: electromagnetic transient model of Yunnan ADPSS full-network electromechanical model + partial wind power and photovoltaic
And (3) fault setting: three-phase short circuit grounding fault of the zixi to deer city line in 3s, and fault removal in 3.1s
Step 1: the fengtun wind power plant adopts constant reactive power control, and the active and reactive curves of the fans are shown in fig. 9 during the fault occurrence period.
Step 2: the fengtun wind power plant adopts the control method of the embodiment, and the active and reactive curves of the fans are shown in fig. 10 during the fault occurrence period.
After additional control is added to the wind power plant of the Fengtun No. 1, the change of the reactive power of the wind power plant of the Fengtun No. 1 is changed from-0.045 to 0.02 to 0.03 to 0.07, the deviation of the absolute value of the reactive power is reduced by 0.25, the change range of the reactive power in the fault period is effectively reduced, meanwhile, the supporting trend of the reactive power in the voltage drop process is ensured, and the system stability is facilitated; meanwhile, the active power maintains the change of 0.14 to 0.17, the change amplitude is also obviously reduced, and the stability of the active power is maintained.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (6)

1. A double-fed asynchronous fan fault ride-through power control method is characterized by comprising the following steps:
step (1), monitoring the effective value U of the voltage of the grid-connected point of the doubly-fed fan in real timerms_measAnd calculating the effective value U of the voltage of the grid-connected pointrms_measAnd a voltage reference value UrefVoltage deviation value Δ U;
step (2), judging whether the power grid voltage falls or rises according to the range of the deviation value delta U;
step (3), when no voltage drop exists, the voltage deviation signal is subjected to dead zone control and then subjected to PI control, and then the reactive power reference value is 0; when the voltage drops or rises, the voltage deviation value delta U crosses the dead zone control, and after PI control, the reactive reference value Q is obtainedrefStarting to change, and starting to output reactive power by the fan;
step (4), the active reference value is obtained according to the reactive reference value and the maximum value obtained in the step (3)Power tracking power PmpptBy the formula
Figure FDA0003027842910000011
Calculating to obtain;
and (5) transmitting the obtained active reference value and reactive reference value signals to a rotor side and network side variable flow control system, thereby realizing the control of the fan.
2. The method for controlling the doubly-fed asynchronous wind turbine fault ride-through power according to claim 1, wherein the specific method in the step (2) is as follows: if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]Within the range, judging that the voltage of a grid connection point is too low, and cutting off the unit; if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefAnd in the above process, judging that the voltage of the grid-connected point is too high, and cutting off the unit.
3. The method for controlling the doubly-fed asynchronous wind turbine fault ride-through power according to claim 1, wherein the specific method in the step (4) is as follows:
if the voltage has no drop, the reactive reference value is 0, and the active reference value Pref＝Pmppt(ii) a If the voltage rises, the reactive power of the power grid is absorbed, and the active reference value Pref＝Pmppt(ii) a If the voltage drops, the reactive reference value begins to change, and the active reference value is based on
Figure FDA0003027842910000012
And reducing to meet the reactive output requirement of the fan.
4. The power control system that asynchronous fan fault of double-fed passed through is characterized in that, includes:
the voltage real-time monitoring module is used for monitoring the effective value U of the voltage of the grid-connected point of the double-fed fan in real timerms_measAnd calculating the effective value U of the voltage of the grid-connected pointrms_measAnd a voltage reference value UrefVoltage deviation value Δ U;
the voltage deviation dead zone control module is used for judging whether the power grid voltage drops or rises or not according to the range of the voltage deviation value delta U;
the reactive reference value calculating module is used for calculating a reactive reference value according to whether the obtained power grid voltage falls or rises;
an active reference value calculation module for tracking power P according to the reactive reference value and the maximum powermpptCalculating an active reference value;
and the rotor side and network side variable flow control systems are used for receiving the active reference value and the reactive reference value so as to realize the control of the fan.
5. The power control system for fault ride-through of the doubly-fed asynchronous wind turbine of claim 4, wherein the method for judging whether the grid voltage drops is as follows: if the voltage deviation value delta U is [ -0.1U [)ref,0]Within the dead zone range, judging that no voltage drop exists; if at (-0.8U)ref,-0.1Uref]Judging that the voltage drops within a non-dead zone range; if at (-1U)ref,-0.8Uref]And in the range, judging that the voltage of the grid connection point is too low, and cutting off the unit.
6. The doubly-fed asynchronous wind turbine fault ride-through power control system of claim 4, wherein the method for judging whether the grid voltage is increased is as follows: if the voltage deviation value delta U is [0,0.05U ]ref]Within the dead zone range, judging that no voltage rises; if at (0.05U)ref,0.3Uref]In the non-dead zone range, judging that the voltage is increased; if at 0.3UrefAnd in the above process, judging that the voltage of the grid-connected point is too high, and cutting off the unit.
CN202110421036.7A 2021-04-19 2021-04-19 Power control method and system for fault ride-through of double-fed asynchronous fan Pending CN113315136A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102214931A (en) * 2011-05-24 2011-10-12 浙江大学 Device and method for low voltage ride through of double-fed inductive wind power generator system
CN105356520A (en) * 2015-11-24 2016-02-24 上海电力学院 Control method for improving low voltage ride through capability of wind power plant
CN106532771A (en) * 2016-12-01 2017-03-22 国网新疆电力公司经济技术研究院 Low-voltage ride-through realization method for double-fed wind turbine generator with adaptive function on voltage drop
CN111682587A (en) * 2020-06-22 2020-09-18 山东大学 Wind driven generator low voltage ride through control method and system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102214931A (en) * 2011-05-24 2011-10-12 浙江大学 Device and method for low voltage ride through of double-fed inductive wind power generator system
CN105356520A (en) * 2015-11-24 2016-02-24 上海电力学院 Control method for improving low voltage ride through capability of wind power plant
CN106532771A (en) * 2016-12-01 2017-03-22 国网新疆电力公司经济技术研究院 Low-voltage ride-through realization method for double-fed wind turbine generator with adaptive function on voltage drop
CN111682587A (en) * 2020-06-22 2020-09-18 山东大学 Wind driven generator low voltage ride through control method and system

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