CN106532739A - Method for enabling wind power unit to participate in primary frequency modulation of power system at different bands - Google Patents

Abstract

The invention provides a method for enabling a wind power unit to participate in primary frequency modulation of a power system at different bands, relates to a technology for enabling the wind power unit to participate in primary frequency modulation of a power network and aims at solving the problem of the contradiction between the wind farm economy and the frequency modulation capacity when the wind power unit participates in primary frequency modulation. The method comprises the steps of firstly separating a high-frequency signal and a low-frequency signal in the power network by using a high-pass filter and a low-pass filter respectively; introducing an inertial control link and a droop control link into the wind power unit and setting an operation mode according to a current wind curtailment condition of a wind farm, wherein the operation mode is an optimal power tracking mode or a suboptimal power tracking mode; and finally calculating electromagnetic power reference values under two operation modes respectively, enabling the electromagnetic power reference values to act on a rotor converter and completing the process that the wind power unit participates in primary frequency modulation of the power system at different bands. According to the method provided by the invention, the target that the wind power unit participates in primary frequency modulation of the power system to the maximum extent when output is not lost is achieved, and the method is suitable for frequency modulation of the wind power unit.

Description

Wind turbines frequency-division section participates in power system primary frequency modulation method

Technical field

The present invention relates to Wind turbines participate in primary frequency regulation of power network technology.

Background technology

Wind-electricity integration operation is the effective form of large-scale development wind energy, but with the continuous lifting of installed capacity of wind-driven power, Original is that leading power supply architecture form there occurs change with thermoelectricity, water power, after wind-powered electricity generation permeability significantly increases, wind-powered electricity generation work( The undulatory property of rate also brings certain impact to the frequency stable and active balance of electrical network, if still only processing Wind turbines It is added in network re-active power equilibrium relation into negative load, huge frequency modulation pressure can be brought to fired power generating unit, not only be made Frequent start-stop into fired power generating unit affects its service life, also largely limits the further development of wind-powered electricity generation.

The control strategy of the primary frequency regulation of power network of Wind turbines participation at present is broadly divided into three kinds：Award setting, inertia control System, Control of decreasing load.Award setting changes power coefficient and then changes grid-connected power by controlling propeller pitch angle, due to pitch Angle is adjusted to mechanical action, and its frequency modulation speed is slow；Inertia control participates in frequency modulation using rotor moment of inertia, in mains frequency ripple Rotor kinetic energy is absorbed or is discharged when dynamic is converted into electromagnetic power, though its frequency modulation speed has compared with fast its frequency regulation capacity of award setting Limit；Control of decreasing load makes running of wind generating set on suboptimum power tracking curve, participates in primary frequency modulation using the active surplus for reserving, Its frequency regulation capacity is big, but Wind turbines longtime running has had a strong impact on the economy of wind energy turbine set in off-load state.

The content of the invention

The invention aims to solving Wind turbines participates in wind field economy and frequency regulation capacity phase lance during primary frequency modulation The problem of shield, it is proposed that consider that the Wind turbines frequency-division section of wind energy turbine set economy participates in power system primary frequency modulation method.

Wind turbines frequency-division section of the present invention participates in power system primary frequency modulation method and comprises the following steps：

Step one, use high pass filterBy vibration frequency in electrical network it is higher thanFrequency departure Signal separator Out, it is designated as Δ f_Hi；Using low pass filterVibration frequency in electrical network is less thanFrequency departure Signal separator go out Come, be designated as Δ f_Li, wherein H_iFor Wind turbines rotor inertia time constant, subscript i represents the i-th typhoon group of motors, and s represents biography Delivery function；

Step 2, inertia control link and droop control link, the inertia control link bag is introduced in Wind turbines Virtual inertia link is included, the virtual inertia link is made up of differentiation element and proportional component two parts, wherein the ratio of proportional component Example coefficient is set to 2H_i；The sagging coefficients R of droop control link_iDetermined by formula (1)；

Wherein, the maximum frequency deviation allowed when △ f are normally run by electrical network, unit are p.u.；P_e1iFor Wind turbines Optimal power under current wind speed, unit are p.u.；P_e2iFor the off-load operation power of Wind turbines, unit is p.u.；

Step 3, according to wind energy turbine set it is current abandon landscape condition arrange operational mode：

If the optimal power under the current wind speed of the i-th typhoon group of motors in wind energy turbine set is P_e1i, there are n platform units in wind energy turbine set, Wind energy turbine set is currently limited and is exerted oneself as P_out, then what wind energy turbine set was current abandons air quantity P_ΔAs shown in formula (2)：

Work as P_ΔWhen≤0, in wind energy turbine set, all units are operated under optimal power tracing mode, are called mode of operation One；

Work as P_Δ>When 0, in wind energy turbine set, the equal off-load of all units is operated under suboptimum power tracking pattern, is called Working mould Formula two；

Step 4, when Wind turbines in mode of operation for the moment, electromagnetic power reference value P_refiAs shown in formula (8)：

P_refi=P_MPPTi-ΔP_Hi (8)

Wherein, P_MPPTiFor optimal power aircraft pursuit course；

When Wind turbines are in mode of operation two, electromagnetic power reference value P_refiAs shown in formula (10)；

P_refi=P_deli-(ΔP_Hi+ΔP_Li) (10)

Electromagnetic power adjusts signal delta P_HiAcquisition methods be：For the vibration frequency isolated in step one is higher than Signal delta f_Hi, the virtual inertia link set in input step two, obtain electromagnetic power adjustment signal △ P_Hi, such as formula (6) It is shown：

Electromagnetic power adjusts signal delta P_LiPreparation method be：For the vibration frequency isolated in step one is less than Signal delta f_Li, droop control link is inputted, electromagnetic power adjustment signal delta P is obtained_Li, as shown in formula (7)：

P_deliFor suboptimum power tracking reference value；

Step 5, by electromagnetic power reference value P_refiRotor current transformer is acted on, primary frequency modulation process is completed.

The present invention according to wind energy turbine set it is current abandon air quantity to determine unit operation in optimal power tracing mode or suboptimum Power tracking pattern, calculates electromagnetic power reference value P under two kinds of different modes respectively_refi, by electromagnetic power reference value P_refiMake For rotor current transformer, primary frequency modulation is realized.The method makes wind by way of by the process of mains frequency deviation signal frequency-division section Group of motors under optimal power tracing mode to mains frequency deviation signal in fast change component response, in suboptimum power tracking mould Under formula to mains frequency deviation signal in fast change component respond with slow component, make Wind turbines ensure itself to exert oneself Under the premise of participate in the primary frequency modulation of electrical network to greatest extent, improve the frequency quality of electrical network.

Description of the drawings

Fig. 1 is that Wind turbines frequency-division section of the present invention participates in power system primary frequency modulation method the general frame；

Fig. 2 is that Wind turbines frequency-division section participates in primary frequency modulation control block diagram；

Fig. 3 is running of wind generating set schematic diagram；

Fig. 4 be suboptimum power tracking curve, v in figure_1i、v_2iAnd v_3iRepresent that the power-rotating speed of blower fan under different wind speed is bent Line；

Fig. 5 is reserve Control of decreasing load schematic diagram, the power of curve 1,2,3 and blower fan under the 4 different wind speed of expressions-turn Fast curve, the wherein wind speed of curve 1 are 11m/s, and the wind speed of curve 2 is 9m/s, and the wind speed of curve 3 is 7m/s, the wind speed of curve 4 For 5m/s；

Fig. 6 is the △ f in embodiment two_HiSignal；

Fig. 7 is wind speed situation of change in certain sound of the wind 200s；

Fig. 8 exerts oneself for wind-powered electricity generation sound optimum；

Fig. 9 is the △ P in embodiment two_HiSignal；

Figure 10 is to survey the system frequency deviation under wind speed；

Figure 11 is that the wind energy conversion system surveyed under wind speed is exerted oneself；

Figure 12 is to survey the wind energy conversion system average output under wind speed；

Figure 13 is the Δ f in embodiment three_HiWith Δ f_LiSignal；

Figure 14 is the Δ P in embodiment three_HiWith Δ P_LiSignal；

Figure 15 is the Δ P in embodiment three_iSignal；

When Figure 16 is 105m/s for wind speed, 2% blower fan of anticlimax load participates in system frequency deviation before and after frequency modulation；

When Figure 17 is 105m/s for wind speed, 1% blower fan of anticlimax load participates in system frequency deviation before and after frequency modulation；

When Figure 18 is 105m/s for wind speed, 1% blower fan of sudden increase in load participates in system frequency deviation before and after frequency modulation；

When Figure 19 is 105m/s for wind speed, 2% blower fan of sudden increase in load participates in system frequency deviation before and after frequency modulation.

Specific embodiment

Specific embodiment one：Wind turbines frequency-division section described in present embodiment participates in power system primary frequency modulation method Comprise the following steps：

Step one：High pass filter of the design as shown in solid box on the left of Fig. 2Vibration frequency in electrical network is high InFrequency departure Signal separator out, be designated as Δ f_Hi；Low pass filter of the design as shown in Fig. 2 left-hand broken line framesVibration frequency in electrical network is less thanFrequency departure Signal separator out, be designated as Δ f_Li；Wherein H_iFor wind turbine Group rotor inertia time constant, subscript i represent the i-th typhoon group of motors, and s represents transmission function；

Step 2：Inertia control link and droop control link, the inertia control link bag is introduced in Wind turbines Virtual inertia link is included, the virtual inertia link is made up of differentiation element and proportional component two parts, wherein the ratio of proportional component Example coefficient is set to 2H_i；In droop control Absent measures block diagram such as Fig. 2 shown in long chain-dotted line part, its sagging coefficients R_iBy formula (1) determine.

Wherein, the maximum frequency deviation allowed when Δ f is normally run by electrical network, unit are p.u.；P_e1iFor Wind turbines Optimal power under current wind speed, unit are p.u.；P_e2iFor the off-load operation power of Wind turbines, unit is p.u..Work as wind R when the non-off-load of group of motors runs_i→ ∞, droop control passage is disconnected.P_e2iValue the abandon air quantity current with wind energy turbine set have Close, the operational mode of its setting method and Wind turbines differentiates the explanation in step 3；

Step 3：Operational mode is arranged according to the landscape condition of abandoning that wind energy turbine set is current.If the i-th typhoon group of motors in wind energy turbine set Optimal power under current wind speed is P_e1i, there are n platform units in wind energy turbine set, wind energy turbine set is currently limited and is exerted oneself as P_out, then wind energy turbine set Current abandons air quantity P_ΔAs shown in formula (2).

Work as P_ΔWhen≤0, in wind energy turbine set, all units are operated under optimal power tracing mode, are called mode of operation One.Under this mode of operation, Wind turbines are run according to optimal power aircraft pursuit course all the time.The operation logic of Wind turbines is as schemed Shown in 3, by current rotor rotational speed omega_rmeasiDetermine optimal power track reference value P_MPPTi, resultant signal Δ P is adjusted with electromagnetic power_i Electromagnetic power reference value P is obtained after superposition_refi, obtain exporting electromagnetic power P after acting on via rotor-side converter_ei, electromagnetism turn Square T_eiWith machine torque T_miTorque official post rotor action.Wherein, realize that the mode of optimal power tracking operation is to maintain blade tip Speed is than being optimum tip-speed ratio λ_MPPTiIt is constant, it is maximal wind-energy usage factor C so as to keep power coefficient_pmaxIt is constant.Most P under excellent power tracking pattern_MPPTiShown in determination mode such as formula (3).

Wherein, ρ is atmospheric density, and unit is kg/m³；r_iFor wind turbine impeller radius, unit is m.

Work as P_Δ>When 0, in wind energy turbine set, the equal off-load of all units is operated under suboptimum power tracking pattern, is called Working mould Formula two.P in suboptimum power tracking curve such as Fig. 4_deliIt is shown, in figure, P_3iFor active surplus, P_MPPTiIt is bent for optimal power tracking Line, P_deliFor off-load curve (being same concept with suboptimum power tracking curve).For example, when Wind turbines off-load is to 80% fortune During row, P_MPPTiIt is to be obtained by the maximum power value point connection under each wind speed, and P_deliBe by under each wind speed most 80% point of high-power value connects what is obtained, and P_3iIt is then both differences, as 20% maximum power value.

If wind energy turbine set is abandoned air quantity P_ΔEvenly distribute to every Fans, then often the off-load of typhoon group of motors runs power P_e2iCan be determined by formula (4).

Under this mode of operation, Wind turbines are according to suboptimum power tracking curve motion.The operation logic of Wind turbines is such as Shown in Fig. 3, by suboptimum power tracking reference value P_deliSubstitute P_MPPTi, resultant signal Δ P is adjusted with electromagnetic power_iObtain after superposition Electromagnetic power reference value P_refiAct on rotor-side converter.Wherein, suboptimum power tracking reference value P_deliDetermined by formula (5).

Wherein, ω_rdeliFor making running of wind generating set in the rotor speed of suboptimum power tracking curve, unit is p.u.； ω_rMPPTiFor making running of wind generating set in the rotor speed of optimal power aircraft pursuit course, unit is p.u..

Step 4, for the vibration frequency isolated in step one it is higher thanSignal delta f_Hi, it is as shown in Figure 2 which is defeated Enter in virtual inertia controlling unit, obtain electromagnetic power adjustment signal delta P_Hi, as shown in formula (6).

Its operation logic is as shown in figure 3, when system frequency is reduced, virtual inertia link exports one strengthens output electromagnetism The signal of power, increases electromagnetic power by the electric current and voltage that change in rotor-side converter, and now electromagnetic power is higher than machine Tool power, rotor speed are reduced, and rotor kinetic energy is converted into electric energy increase Wind turbines and exerts oneself；When system frequency is raised, superposition One signal for weakening output electromagnetic power reduces electromagnetic power, and now electromagnetic power is less than mechanical output, and rotor speed is raised, Electric energy is converted into rotor kinetic energy storage.And as controlled plant for vibration frequency is higher thanSignal, rotor movement time Less than rotor inertia time constant, rotor is in dynamic equilibrium all the time in operating state energy all the time, it is ensured that Wind turbines Average output is constant under long time scale, and the processing method of the part signal is in 2 two kinds of moulds of mode of operation one and mode of operation Can come into operation under formula.

For the vibration frequency isolated in step one is less thanSignal delta f_Li, can only carry out under mode of operation two Process.As shown in Figure 3 by the part signal feed-in droop control link after, obtain electromagnetic power adjustment signal delta P_Li, such as formula (7) It is shown.

Step 5, as shown in figure 3, adjustment signal delta P_LiWith Δ P_HiThe resultant signal Δ of electromagnetic power adjustment is obtained after superposition P_i, negated and suboptimum power tracking reference value P_deliSuperposition, obtains electromagnetic power reference value P_refi, electromagnetic power is referred to Value P_refiRotor current transformer is acted on, electromagnetic power P is obtained_ei。

Under pattern two, every unit is with P_e2iPower off-load operation, reserve active surplus P that can be used for frequency modulation_e1i- P_e2i.Wind turbines off-load operation frequency modulation principle as shown in figure 5, in figure dotted line be optimal power tracking mode, the solid line in left side Two kinds of off-load operational modes are represented respectively with the chain-dotted line on right side.Under conditions of propeller pitch angle is constant, for arbitrary fixed wind speed Operating mode, in addition to maximum power point, the point that can all have two wind power coefficients the same is such as caught for 9m/s time point A and E in wind speed The wind power for obtaining is the same, but generator amature rotating speed is different, is respectively at high rotating speed and the slow-speed of revolution.Due to being subtracted using increasing rotating speed During load pattern, some energy can be stored as rotor kinetic energy, be more beneficial for the utilization of energy, therefore selected right side Chain-dotted line representated by off-load operational mode.When wind speed is 9m/s, A point of the Wind turbines under off-load state, now Load increase causes frequency to decline, and droop control link exports one and increases the signal exerted oneself, and converter quick acting increases electromagnetism Performance number so that electromagnetic power rises to B points more than slow mechanical output, electromagnetic power is adjusted by the A point moments in Fig. 5, And mechanical output then slowly rises along characteristic curve A-F sections, now electromagnetic power is more than mechanical output, and rotor speed gradually drops Low, electromagnetic power is also declined along maximum power tracking curve gradually by B points, is finally reached new balance in F points, is achieved in Off-load frequency modulation of the Wind turbines under rotor speed control.

Understand with reference to step 4, Wind turbines in mode of operation to vibration frequency are higher than only onceSignal delta f_HiRing Should, droop control passage disconnects.Electromagnetic power reference value P obtained under the pattern_refiAs shown in formula (8).

P_refi=P_MPPTi-ΔP_Hi (8)

Formula (9) can be obtained by formula (3), formula (8).

And work as Wind turbines under mode of operation two, to vibration frequency it is higher thanSignal delta f_HiIt is less than with vibration frequencySignal delta f_LiRespond, electromagnetic power reference value P obtained under the pattern_refiAs shown in formula (10).

P_refi=P_deli-(ΔP_Hi+ΔP_Li) (10)

Formula (11) is obtained by formula (5), formula (6), formula (7).

Specific embodiment two：With the measured data intercepted in 4 points to the 5 points periods of certain wind energy turbine set, wind-powered electricity generation permeability is set up For 20% wind-fire joint frequency modulation model, emulated using the disturbance that one group of standard deviation is 0.008.60 are had in the wind energy turbine set Platform 2MW units, unit model W2000-87, current restriction are exerted oneself as 120MW, do not occur abandoning wind.W2000-87 model wind-force Electromotor basic parameter is as shown in table 1.

Table 1：2000-87 model wind-driven generator basic parameters

Step one：Wind turbines rotor inertia time constant H_iFor 5s, the high pass as shown in solid box on the left of Fig. 2 is designed Wave filterIt is higher than frequency departure signal delta f of 0.2Hz by vibration frequency in electrical network_HiSeparate, as shown in Figure 6；

Step 2：Inertia control, short point in additional virtual inertia Absent measures block diagram such as Fig. 2 is introduced in Wind turbines Shown in dashed part, it is made up of differentiation element and proportional component two parts, its proportionality coefficient is set to 2H_i, as 10s.Due to Wind turbines now non-off-load operation, R_i→ ∞, droop control passage is disconnected.The differentiation of running of wind generating set pattern is in step Illustrate in three；

Step 3：Operational mode is arranged according to the landscape condition of abandoning that wind energy turbine set is current.There is the wind energy turbine set of 60 2MW Wind turbines It is current to limit the P that exerts oneself_outFor 120MW, by wind speed situation of change in wind energy turbine set 200s as shown in Figure 7, wind-powered electricity generation in the correspondence period is known Optimal power of the field under current wind speedAs shown in Figure 8.By formula (1) know wind energy turbine set it is current abandon air quantity P_Δ≤0。

By P_Δ≤ 0, in wind energy turbine set, all units operate in mode of operation one, under optimal power tracing mode.In this work Under operation mode, Wind turbines are run according to optimal power aircraft pursuit course all the time.The operation logic of Wind turbines as shown in figure 3, by Current rotor rotational speed omega_rmeasiDetermine optimal power track reference value P_MPPTi, resultant signal Δ P is adjusted with electromagnetic power_iAfter superposition To electromagnetic power reference value P_refi, obtain exporting electromagnetic power P after acting on via rotor-side converter_ei, electromagnetic torque T_eiWith machine Tool torque T_miTorque official post rotor action.Realize that the mode of optimal power tracking operation is to maintain tip speed ratio for optimal blade tip Speed compares λ_MPPTiIt is constant, it is maximal wind-energy usage factor C so as to keep power coefficient_pmaxIt is constant.Atmospheric density is taken as 1.295kg/m³, the P under optimal power tracing mode_MPPTiShown in determination mode such as formula (2).

Step 4：For the vibration frequency isolated in step one is higher than signal delta f of 0.2Hz_Hi, as shown in Figure 2 by which In input virtual inertia controlling unit, electromagnetic power adjustment signal delta P is obtained by formula (3)_Hi, as shown in Figure 9.

Step 5：Wind turbines are higher than only once signal delta f of 0.2Hz to vibration frequency in mode of operation_HiResponse, the mould Electromagnetic power reference value P obtained by formula (4) under formula_refiAs shown in the chain-dotted line in Figure 11.

Mains frequency and wind energy conversion system according to being obtained by the frequency modulation method of step one to step 5 exert oneself situation of change difference As shown in Figure 10 and Figure 11.In figure, solid line has neither part nor lot in situation when primary frequency modulation relies only on fired power generating unit frequency modulation for Wind turbines, Chain-dotted line shares jointly situation during primary frequency modulation task for Wind turbines participation primary frequency modulation Wind turbines with fired power generating unit.By The simulation result relative analyses of Figure 10 know, under actual wind speed Wind turbines inertia control improve system frequency dynamic it is stable Property, when Wind turbines have neither part nor lot in primary frequency modulation, the variance of system frequency deviation is 3.1776 × 10^-6Pu, and Wind turbines participate in one The variance of the system frequency deviation after secondary frequency modulation is 2.5939 × 10^-6Pu, due to the inertial control system frequency of Wind turbines it is inclined Poor variance drops to original 0.8 times.When system frequency is reduced, virtual inertia link exports one strengthens output electromagnetism The signal of power, increases electromagnetic power by the electric current and voltage that change in rotor-side converter, and now electromagnetic power is higher than machine Tool power, rotor speed are reduced, and rotor kinetic energy is converted into electric energy increase Wind turbines and exerts oneself；When system frequency is raised, superposition One signal for weakening output electromagnetic power reduces electromagnetic power, and now electromagnetic power is less than mechanical output, and rotor speed is raised, Electric energy is converted into rotor kinetic energy storage.

And average output of Wind turbines when having neither part nor lot in primary frequency modulation is 0.7786pu, after Wind turbines participate in primary frequency modulation Average output be 0.7785pu, as shown in figure 12 (in Figure 12, solid line overlaps with chain-dotted line), it is tactful with this to draw Wind turbines Participating in during primary frequency modulation exerting oneself which does not affect.Demonstrate when controlled plant be vibration frequency higher than 0.2 signal when, due to Rotor is less than rotor inertia time constant movement time, and rotor is in operating state all the time, and energy is in dynamic equilibrium all the time, protects The average output of card Wind turbines is constant under long time scale.

Specific embodiment three：With the measured data intercepted in 3 points to the 4 points periods of certain wind energy turbine set, wind-powered electricity generation permeability is set up For 20% wind-fire joint frequency modulation model, the use of one group of standard deviation is 0.008 disturbance and being combined that step signal is formed by stacking Disturbance is emulated.60 2MW units, unit model W2000-87, its basic parameter such as 1 institute of table is had in the wind energy turbine set Show.When wind speed is 10.5m/s, wind energy turbine set is limited and is exerted oneself as 94MW.

Step one：Wind turbines rotor inertia time constant H_iFor 5s, the high pass as shown in solid box on the left of Fig. 2 is designed Wave filterIt is higher than frequency departure signal delta f of 0.2Hz by vibration frequency in electrical network_HiSeparate, the reality in such as Figure 13 (by taking network load anticlimax 1% as an example) shown in line；Low pass filter of the design as shown in Fig. 2 left-hand broken line framesBy electricity Frequency departure signal delta f of the vibration frequency less than 0.2Hz in net_LiSeparate, (with network load as shown in Figure 13 chain lines As a example by anticlimax 1%)；

Step 2：Inertia control, short point in additional virtual inertia Absent measures block diagram such as Fig. 2 is introduced in Wind turbines Shown in dashed part, it is made up of differentiation element and proportional component two parts, its proportionality coefficient is set to 2H_i, as 10s.Electrical network The maximum frequency deviation Δ f allowed during normal operation is 4 × 10^-3P.u., optimal power of the Wind turbines under current wind speed P_e1iFor 0.7824p.u., the off-load operation power P of Wind turbines_e2iFor 0.7042p.u., P_e2iValue and wind energy turbine set it is current Abandon air quantity relevant, the explanation in step 3 of its setting method.Long chain-dotted line part institute in droop control Absent measures block diagram such as Fig. 2 Show, its sagging coefficients R is obtained by formula (1)_iFor 0.05.

Step 3：Operational mode is arranged according to the landscape condition of abandoning that wind energy turbine set is current.When wind speed is 10.5m/s, there are 60 The wind energy turbine set of 2MW Wind turbines limits the P that exerts oneself_outFor 84MW, by formula (2) know wind energy turbine set it is current abandon air quantity P_ΔFor 9.89MW.

By P_Δ>0, in wind energy turbine set, the equal off-load of all units operates in mode of operation two, under suboptimum power tracking pattern.By wind Electric field abandons air quantity P_ΔEvenly distribute to every Fans, the off-load operation power P of Wind turbines is known by formula (3)_e2iFor 0.7042p.u.。

Suboptimum power tracking curve as shown in figure 4, in figure, P_3iFor active surplus, P_MPPTiFor optimal power aircraft pursuit course, P_deliFor off-load curve.Now, Wind turbines off-load is run to 90%, P_MPPTiIt is by the maximum power value point under each wind speed What connection was obtained, and P_deliIt is to be obtained by 90% point of connection of the maximum power value under each wind speed, and P_3iIt is then both Difference, as 10% maximum power value.

Under this mode of operation, Wind turbines according to suboptimum power tracking curve motion, its suboptimum power tracking reference value P_deliDetermined by formula (4).

Wherein, ω_rdeliFor making running of wind generating set in the rotor speed of suboptimum power tracking curve, unit is p.u.； ω_rMPPTiFor making running of wind generating set in the rotor speed of optimal power aircraft pursuit course, unit is p.u..

Step 4：For the vibration frequency isolated in step one is higher than signal delta f of 0.2Hz_Hi, as shown in Figure 2 by which In input virtual inertia controlling unit, electromagnetic power adjustment signal delta P is obtained by formula (5)_Hi, it is shown in solid in such as Figure 14.

For the vibration frequency isolated in step one is less than signal delta f of 0.2Hz_Li, as shown in Figure 2 by the part signal After feed-in droop control link, electromagnetic power adjustment signal delta P is obtained by formula (4)_Li, as shown in phantom in Figure 14.

As shown in figure 3, adjustment signal delta P_LiWith Δ P_HiThe resultant signal Δ P of electromagnetic power adjustment is obtained after superposition_i, such as Figure 15 It is shown.Wind turbines, under mode of operation two, are higher than signal delta f of 0.2Hz to vibration frequency_Hi0.2Hz is less than with vibration frequency Signal delta f_LiRespond.

Step 5, by Δ P_iNegate and suboptimum power tracking reference value P_deliSuperposition obtains electromagnetic power reference value by formula (5) P_refi。

According to the frequency modulation method by step one to step 5, the system stable to distinguishes anticlimax load in 10s 2%th, anticlimax load 1%, sudden increase in load 1%, sudden increase in load 2%, the simulation result of mains frequency situation of change point in its 200s Not as shown in Figure 16, Figure 17, Figure 18, Figure 19.When in figure, solid line has neither part nor lot in primary frequency modulation for blower fan and relies only on fired power generating unit frequency modulation Situation, chain-dotted line is that blower fan participates in system frequency when primary frequency modulation Wind turbines and fired power generating unit share primary frequency modulation task jointly The situation of change of rate deviation.From simulation result, after wind-powered electricity generation participates in primary frequency modulation, when sudden load change 2%, system frequency is inclined Difference change amplitude 0.0032pu is decreased to by 0.0037pu, when sudden load change 2% system frequency deviation change amplitude by 0.0019pu is decreased to 0.0016pu, and the stability for demonstrating system frequency after Wind turbines participate in primary frequency modulation strengthens.

Claims (2)

1. Wind turbines frequency-division section participates in power system primary frequency modulation method, it is characterised in that comprise the following steps：

Step one, use high pass filterBy vibration frequency in electrical network it is higher thanFrequency departure Signal separator out, It is designated as Δ f_Hi；Using low pass filterVibration frequency in electrical network is less thanFrequency departure Signal separator out, note For Δ f_Li, wherein H_iFor Wind turbines rotor inertia time constant, subscript i represents the i-th typhoon group of motors, and s represents transmission letter Number；

Step 2, inertia control link and droop control link is introduced in Wind turbines, the inertia control link includes void Intend inertial element, the virtual inertia link is made up of differentiation element and proportional component two parts, wherein the ratio system of proportional component Number is set to 2H_i；The sagging coefficients R of droop control link_iDetermined by formula (1)；

$R_i=\frac{\mathrm{\Δ}f}{P_{e1i}-P_{e2i}}---\left(1\right))$

Wherein, the maximum frequency deviation allowed when Δ f is normally run by electrical network, unit are p.u.；P_e1iWorking as Wind turbines Optimal power under front wind speed, unit are p.u.；P_e2iFor the off-load operation power of Wind turbines, unit is p.u.；

Step 3, according to wind energy turbine set it is current abandon landscape condition arrange operational mode：

If the optimal power under the current wind speed of the i-th typhoon group of motors in wind energy turbine set is P_e1i, in wind energy turbine set, have n platform units, wind-powered electricity generation The current restriction in field is exerted oneself as P_out, then what wind energy turbine set was current abandons air quantity P_ΔAs shown in formula (2)：

$P_{\mathrm{\Δ}}=\underset{i=1}{\overset{n}{\Σ}}{P}_{e1i}-P_{out}---\left(2\right)$

Work as P_ΔWhen≤0, in wind energy turbine set, all units are operated under optimal power tracing mode, are called mode of operation one；

Work as P_Δ>When 0, in wind energy turbine set, the equal off-load of all units is operated under suboptimum power tracking pattern, is called mode of operation two；

Step 4, when Wind turbines in mode of operation for the moment, electromagnetic power reference value P_refiAs shown in formula (8)：

P_refi=P_MPPTi-ΔP_Hi (8)

Wherein, P_MPPTiFor optimal power aircraft pursuit course；

When Wind turbines are in mode of operation two, electromagnetic power reference value P_refiAs shown in formula (10)；

P_refi=P_deli-(ΔP_Hi+ΔP_Li) (10)

Electromagnetic power adjusts signal delta P_HiAcquisition methods be：For the vibration frequency isolated in step one is higher thanLetter Number Δ f_Hi, the virtual inertia link set in input step two, obtain electromagnetic power adjustment signal delta P_Hi, such as formula (6) institute Show：

${\mathrm{\ΔP}}_{Hi}=2H_i\frac{d\left({\mathrm{\Δf}}_{Hi}\right)}{dt}---\left(6\right)$

Electromagnetic power adjusts signal delta P_LiPreparation method be：For the vibration frequency isolated in step one is less thanLetter Number Δ f_Li, droop control link is inputted, electromagnetic power adjustment signal delta P is obtained_Li, as shown in formula (7)：

${\mathrm{\ΔP}}_{Li}=\frac{{\mathrm{\Δf}}_{Li}}{R_i}---\left(7\right)$

P_deliFor suboptimum power tracking reference value；

Step 5, by electromagnetic power reference value P_refiRotor current transformer is acted on, primary frequency modulation process is completed.

2. method according to claim 1, it is characterised in that suboptimum power tracking reference value P_deliDetermined by formula (5)：

$P_{deli}=P_{e2i}+(P_{e1i}-P_{e2i})\·\frac{{\mathrm{\ω}}_{rdeli}-{\mathrm{\ω}}_{rmeasi}}{{\mathrm{\ω}}_{rdeli}-{\mathrm{\ω}}_{rMPPTi}}---\left(5\right)$

Wherein, ω_rdeliFor making running of wind generating set in the rotor speed of suboptimum power tracking curve, unit is p.u.；ω_rMPPTi For making running of wind generating set in the rotor speed of optimal power aircraft pursuit course, unit is p.u., ω_rmeasiFor current rotor rotating speed.