CN105356459A - A control method for allowing electric automobiles to participate in power system frequency modulation in a scattered grid-access manner - Google Patents

Abstract

The invention discloses a control method for allowing electric automobiles to participate in power system frequency modulation in a scattered grid-access manner. The method mainly comprises the following steps: 1) a V2G control center inquires the number, SOC and power quota information and the like of V2G participating in frequency modulation in the region; 2) a dispatching center obtains participatable frequency modulation capacity reported by each V2G control center; 3) the V2G control center obtains a power command Pr sent by the dispatching center; 4) corresponding V2Gs are selected to participate in the frequency modulation control method according to the vehicle demands of users: if the user has a requirement for fetching the vehicle at any time, and the SOC is larger than 0.6 and smaller than 0.8, the electric automobile is in a ready modulation mode, and if the user has a fixed time period when the vehicle is not used, and the SOC is larger than 0.3 and smaller than 0.8, the electric automobile is in a fixed modulation mode, or otherwise, the electric automobile does not participate in frequency modulation; 5) the V2G participate in the frequency modulation according to the corresponding mode; and 6) system frequency is detected, if the system frequency is recovered, the V2G quits the frequency modulation, or otherwise, the steps above are carried out repeatedly until the system frequency is recovered.

Description

A kind of electric automobile dispersion networks and participates in the control method of electric power system frequency modulation

Technical field

The present invention relates to a kind of electric automobile dispersion networking and participate in electric power system frequency modulation method, belong to electric vehicle engineering field.

Background technology

Energy crisis and environmental pollution have impelled the fast development of electric automobile industry, the popularization day by day of electric automobile, also for the development of electrical network provides new opportunity.Can realize the acquisition of the flow of power between electrical network and electric automobile particularly by electric automobile-electrical network interaction technique (VehicletoGrid, V2G), electric automobile can provide some assistant service abilities for electrical network.Wherein, frequency modulation is considered to the service of the potential and practicality of most.

Consider that electric automobile is as the vehicles, the demand of user is primary goal.Participate in, in system frequency modulation, often all seldom considering the user demand of electric automobile user at existing electric automobile, mostly concentrate the primary frequency modulation considering electric power system, or only consider centralized V2G mode.The present invention proposes the electric automobile power distribution strategies that the power division of control centre and V2G control centre and V2G control centre and each disperse to access.On this basis, consider the demand of electrical network, EV and user three aspect, proposing a kind of electric automobile adopts dispersion access module to participate in the control strategy of system frequency modulation, for the driving arrangement of different users, propose corresponding participation frequency modulation control method: " with tune " pattern and " Gu tune " pattern.

Summary of the invention

The invention provides the dispersion of a kind of electric automobile to network and participate in electric power system frequency modulation method, this method give V2G control centre and each disperses the power distribution strategies of the electric automobile accessed.On this basis, based on the driving arrangement of user, propose two kinds of hopping pattern.

Put forward the methods of the present invention, comprises following steps:

Step 1), the information such as V2G quantity, state-of-charge SOC and the power allowances participating in frequency modulation are inquired about by V2G control centre;

Step 2), control centre obtains participated in the frequency regulation capacity S that V2G control centre reports _i;

Step 3), the capacity that control centre reports according to V2G control centre, frequency modulation power P _totalpro rata distribution, then each V2G control centre obtains the power command P that control centre issues _r;

$P_r=P_{total}*\frac{S_i}{{\mathrm{\ΣS}}_i}$

Step 4), V2G control centre uses car demand according to user, selects corresponding V2G to participate in frequency modulation control method.If user has the demand and full this condition of 0.6<SOC<0.8 of picking up the car at any time, such electric automobile carries out step 5 " with tune " pattern; If user has the fixing period without car and meet this condition of 0.3<SOC<0.8, such electric automobile carries out step 6 " Gu tune " pattern, otherwise does not participate in frequency modulation;

Step 5), pattern that V2G terminal adopts " with tune ", V2G participates in primary frequency modulation.After getting mains frequency skew, formulate electric automobile charge-discharge electric power P according to droop control principle _i,k

P _i,k＝K*Δf

If the then discharge and recharge P of electric automobile _i,kbe greater than maximum charge-discharge electric power, then make P _i,kafter=maximum charge-discharge electric power, then export P _i,k; Otherwise, directly export P _i,k;

Step 6), pattern that V2G terminal adopts " Gu tune ", according to SOC value, control V2G switches between primary frequency modulation and frequency modulation frequency modulation;

Step 6.1), if SOC is in [0.6,0.8] this interval, this electric automobile participates in frequency modulation frequency modulation, carry out step 6.2; Otherwise this electric automobile participates in primary frequency modulation, carry out step 6.4;

Step 6.2), V2G control centre distributes frequency modulation frequency modulation power P to electric automobile in proportion _{2, i};

Step 6.2.1), the P issued according to control centre _r, calculate each automobile charge-discharge electric power P _i;

As the P that control centre issues _rduring for charge power, the charge power P of each V2G _ifor:

P _i＝P _r(1-SOC _i)/∑(1-SOC _i)

When the Pr issued when control centre is discharge power, the discharge power P of each V2G _ifor:

$P_i=P_r({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })/\mathrm{\&Sigma;}({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })$

Step 6.2.2), by each automobile charge-discharge electric power P _icompare with maximum charge-discharge electric power, if out-of-limit, then make P _i=maximum charge-discharge electric power, gets rid of this numbering, by P simultaneously in N _sumaccumulative automobile reaches the power total value of maximum charge-discharge electric power;

Step 6.2.3), according to formula P _r=P _r-P _sum, obtain new P _r;

Step 6.2.4), the P newly obtained _rin new N, circulate above-mentioned process, until distributed to V2G to greatest extent;

Step 6.2.5), to each automobile transmit power command;

Step 6.3), if the frequency modulation frequency modulation power P of electric automobile _{2, i}be greater than maximum charge-discharge electric power, make P _{2, i}after=maximum charge-discharge electric power, export frequency modulation frequency modulation power P _{2, i}; Otherwise, directly export P _{2, i};

Step 6.4), first after getting mains frequency skew, formulate electric automobile charge/discharge power P according to droop control principle _i,k, wherein sagging coefficient gets maximum; Then the charge power P of electric automobile is calculated _i ^c, according to above-mentioned result of calculation, obtain the primary frequency modulation power P of electric automobile _{1, i}

P _1,i＝P _i,k+P _i ^c

If the primary frequency modulation P of electric automobile _{1, i}be greater than maximum charge-discharge electric power, make P _{1, i}after=maximum charge-discharge electric power, export primary frequency modulation power P _{1, i}; Otherwise, directly export P _{1, i};

Step 6.5), the SOC information of inquiry electric automobile, if electric automobile is in the process participating in frequency modulation frequency modulation, SOC value <0.6, is now switched to primary frequency modulation pattern; If electric automobile is in the process participating in primary frequency modulation, SOC value >0.6, is now switched to frequency modulation frequency modulation pattern;

Step 7), detection system frequency detection system frequency, if system frequency is recovered, then exits frequency modulation; Otherwise repetition above-mentioned steps, until system frequency is recovered.

Further, the present invention, with in mode transfer formula, can be described as in the frequency droop control structure maintaining battery charge state: droop control device offsets according to mains frequency, formulates electric automobile charge/discharge power.The control method of described droop control device is as follows:

Work as SOC _i ^min≤ SOC _i,k≤ SOC _i ⁱⁿ, time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+a)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-a)\end{array}\right.$

Work as SOC _i ⁱⁿ≤ SOC _i,k≤ SOC _i ^max, time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+b)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-b)\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^mintime:

$\left\{\begin{array}{c}{K}_{i,k}^c=K_{max}\\ K_{i,k}^d=0\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^maxtime:

$\left\{\begin{array}{c}{K}_{i,k}^c=0\\ K_{i,k}^d=K_{max}\end{array}\right.$

In above-mentioned formula, SOC _i,kfor the state-of-charge of k moment i-th batteries of electric automobile; SOC _i ^minbe that i-th electric automobile allows minimum state-of-charge; SOC _i ^maxbe that i-th electric automobile allows maximum state-of-charge; SOC _i ⁱⁿit is the initial state-of-charge of i-th electric automobile; K _maxfor the sagging coefficient of maximum charge/discharge; K ^c _i,kbe i-th electric automobile, charge sagging coefficient in the k moment; K ^d _i,kbe i-th electric automobile, discharge sagging coefficient in the k moment.

Compared with prior art, tool has the following advantages in the present invention:

1. for there is the reliability of signal and the containing problem of cost of investment these two aspects in current frequency signal obtain manner, this clearly demarcated concept proposing V2G control centre.By electric automobile subregion, accepted the instruction of higher level's scheduling by the V2G control centre in each region, while ensure that frequency signal obtains reliability, decrease cost of investment to a certain extent.

2. the present invention proposes a kind of V2G control centre to each electric automobile frequency modulation power distribution strategies.According to pro rata distribution method, give each electric motor car in this region by frequency modulation power division, participate in the frequency modulation amount of frequency modulation as electric automobile.

3. the present invention is with the demand of user for primary goal, proposes two kinds of patterns that electric automobile participates in frequency modulation: " with tune " pattern and " Gu mode transfer formula ".When user needs to take electric automobile at any time, " with tune " pattern can be selected, control electric automobile and only participate in primary frequency modulation; When user within the fixing period without driving demand time, can select " solid adjust " pattern, and according to the SOC value of electric automobile, control electric automobile switches once charging between frequency modulation and frequency modulation frequency modulation.

Accompanying drawing explanation

Fig. 1 V2G participates in the main flow of electric power system frequency modulation

Fig. 2 V2G participates in power grid frequency modulation equivalent schematic

Fig. 3 V2G control centre power division flow chart

Fig. 4 participates in the main flow of primary frequency modulation with V2G under mode transfer formula

Under the solid mode transfer formula of Fig. 5, V2G participates in a frequency modulation frequency modulation flow process

Embodiment

With reference to shown in Fig. 1, the invention provides the control method that a kind of electric automobile dispersion networking participates in electric power system frequency modulation, wherein V2G control centre and the communication signal direction between control centre and V2G as shown in Figure 2, specifically comprise following steps:

Step 1), the information such as V2G quantity, SOC and the power allowances participating in frequency modulation are inquired about by V2G control centre;

Step 2), control centre obtains participated in the frequency regulation capacity S that V2G control centre reports _i;

Step 3), the capacity that control centre reports according to V2G control centre, frequency modulation power P _totalpro rata distribution, then each V2G control centre obtains the power command P that control centre issues _r;

$P_r=P_{total}*\frac{S_i}{{\mathrm{\&Sigma;S}}_i}$

Step 4), V2G control centre uses car demand according to user, selects corresponding V2G to participate in frequency modulation control method.If user has the demand and full this condition of 0.6<SOC<0.8 of picking up the car at any time, such electric automobile carries out step 5 " with tune " pattern; If user has the fixing period without car and full this condition of 0.3<SOC<0.8, such electric automobile carries out step 6 " Gu tune " pattern; Otherwise do not participate in frequency modulation;

Step 5), pattern that V2G terminal adopts " with tune ", participate in primary frequency modulation, as shown in Figure 4, step is as follows;

Step 5.1), obtain frequency fluctuation signal delta f;

Step 5.2), according to SOC initial value, calculate droop control COEFFICIENT K;

Step 5.3), according to the result of calculation of step 4.2, determine the discharge and recharge P of electric automobile _i,k;

P _i,k＝K*Δf

Step 5.4), if the discharge and recharge P of electric automobile _i,kbe greater than maximum charge-discharge electric power, make P _i,kafter=maximum charge-discharge electric power, then export P _i,k; Otherwise, directly export P _i,k;

Step 6), pattern that V2G terminal adopts " Gu tune ", according to SOC value, control V2G switches between primary frequency modulation and frequency modulation frequency modulation, and as shown in Figure 5, step is as follows;

Step 6.1), if SOC is in [0.6,0.8] this interval, this electric automobile participates in frequency modulation frequency modulation, carry out step 6.2; Otherwise this electric automobile participates in primary frequency modulation, carry out step 6.4;

Step 6.2), V2G control centre distributes frequency modulation frequency modulation power P to electric automobile in proportion _{2, i}, as shown in Figure 3;

Step 6.2.1), the P issued according to control centre _r, calculate each automobile charge-discharge electric power P _i;

As the P that control centre issues _rduring for charge power, the charge power P of each V2G _ifor:

P _i＝P _r(1-SOC _i)/∑(1-SOC _i)

When the Pr issued when control centre is discharge power, the discharge power P of each V2G _ifor:

$P_i=P_r({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })/\mathrm{\&Sigma;}({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })$

Step 6.2.2), by each automobile charge-discharge electric power P _icompare with maximum charge-discharge electric power, if out-of-limit, then make P _i=maximum charge-discharge electric power, gets rid of this numbering, by P simultaneously in N _sumaccumulative automobile reaches the power total value of maximum charge-discharge electric power;

Step 6.2.3), according to formula P _r=P _r-P _sum, obtain new P _r;

Step 6.2.4), the P newly obtained _rin new N, circulate above-mentioned process, until distributed to V2G to greatest extent;

Step 6.2.5), to each automobile transmit power command;

Step 6.3), if the frequency modulation frequency modulation power P of electric automobile _{2, i}be greater than maximum charge-discharge electric power, make P _{2, i}after=maximum charge-discharge electric power, export frequency modulation frequency modulation power P _{2, i}; Otherwise, directly export P _{2, i};

Step 6.4), V2G participates in primary frequency modulation;

Step 6.4.1), obtain frequency fluctuation signal delta f;

Step 6.4.2), sagging coefficient gets maximum, calculates the discharge and recharge P of electric automobile _i,k;

P _i,k＝K _max*Δf

Step 6.4.3), calculate the charge power P of electric automobile _i ^c;

$P_i^c=({\mathrm{SOC}}_i^e-{\mathrm{SOC}}_i^{now})*E_i^r/(t_i^{out}-t_i^{now})$

Step 6.4.4), according to the result of calculation of step 6.4.3 and step 6.4.4, calculate the primary frequency modulation power P of electric automobile _{1, i}

P _1,i＝P _i,k+P _i ^c

Step 6.4.5) if the primary frequency modulation power P of electric automobile _{1, i}be greater than maximum charge-discharge electric power, make P _{1, i}after=maximum charge-discharge electric power, export primary frequency modulation power P _{1, i}; Otherwise, directly export P _{1, i};

Step 6.5), the SOC information of inquiry electric automobile, if electric automobile is in the process participating in frequency modulation frequency modulation, SOC value <0.6, is now switched to primary frequency modulation pattern; If electric automobile is in the process participating in primary frequency modulation, SOC value >0.6, is now switched to frequency modulation frequency modulation pattern;

Step 7), detection system frequency detection system frequency, if system frequency is recovered, then exits frequency modulation; Otherwise repetition above-mentioned steps, until system frequency is recovered.

Because user needs to take automobile at any time, " with tune " pattern that the present invention proposes, idiographic flow as shown in Figure 4, wherein sagging COEFFICIENT K and SOC physical relationship as follows:

Work as SOC _i ^min≤ SOC _i,k≤ SOC _i ⁱⁿ, time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+a)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-a)\end{array}\right.$

Work as SOC _i ⁱⁿ≤ SOC _i,k≤ SOC _i ^max, time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+b)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-b)\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^mintime:

$\left\{\begin{array}{c}{K}_{i,k}^c=K_{max}\\ K_{i,k}^d=0\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^maxtime:

$\left\{\begin{array}{c}{K}_{i,k}^c=0\\ K_{i,k}^d=K_{max}\end{array}\right.$

In above-mentioned formula, SOC _i,kfor the state-of-charge of k moment i-th batteries of electric automobile; SOC _i ^minbe that i-th electric automobile allows minimum state-of-charge; SOC _i ^maxbe that i-th electric automobile allows maximum state-of-charge; SOC _i ⁱⁿit is the initial state-of-charge of i-th electric automobile; K _maxfor the sagging coefficient of maximum charge/discharge; K ^c _i,kbe i-th electric automobile, charge sagging coefficient in the k moment; K ^d _i,kbe i-th electric automobile, discharge sagging coefficient in the k moment.

Claims (3)

1. electric automobile dispersion networks and participates in a control method for electric power system frequency modulation, and it is characterized in that, the method comprises the steps:

Step 1), the information such as V2G quantity, SOC and the power allowances participating in frequency modulation are inquired about by V2G control centre;

Step 2), control centre obtains participated in the frequency regulation capacity S that V2G control centre reports _i;

Step 3), the capacity that control centre reports according to V2G control centre, frequency modulation power P _totalpro rata distribution, then each V2G control centre obtains the power command P that control centre issues _r;

$P_r=P_{total}*\frac{S_i}{{\mathrm{\&Sigma;S}}_i}$

Step 4), V2G control centre uses car demand according to user, corresponding V2G is selected to participate in frequency modulation control: if user has the demand and full this condition of 0.6<SOC<0.8 of picking up the car at any time, such electric automobile carries out step 5 " with tune " pattern; If user has the fixing period without car and meet this condition of 0.3<SOC<0.8, such electric automobile carries out step 6 " Gu tune " pattern, otherwise does not participate in frequency modulation;

Step 5), pattern that V2G terminal adopts " with tune ", V2G participates in primary frequency modulation.After getting mains frequency skew, formulate electric automobile charge-discharge electric power P according to droop control principle _i,k

P _i,k＝K*Δf

If the charge-discharge electric power P of electric automobile _i,kbe greater than maximum charge-discharge electric power, then make P _i,kafter=maximum charge-discharge electric power, then export P _i,k; Otherwise, directly export P _i,k;

Step 6), pattern that V2G terminal adopts " Gu tune ", according to SOC value, control V2G switches between primary frequency modulation and frequency modulation frequency modulation;

Step 6.1), if SOC is in [0.6,0.8] this interval, this electric automobile participates in frequency modulation frequency modulation, carry out step 6.2; Otherwise this electric automobile participates in primary frequency modulation, carry out step 6.4;

Step 6.2), V2G control centre distributes frequency modulation frequency modulation power P to electric automobile in proportion _{2, i};

Step 6.2.1), the P issued according to control centre _r, calculate each automobile charge-discharge electric power P _i;

As the P that control centre issues _rduring for charge power, the charge power P of each V2G _ifor:

P _i＝P _r(1-SOC _i)/∑(1-SOC _i)

When the Pr issued when control centre is discharge power, the discharge power P of each V2G _ifor:

$P_i=P_r({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })/\mathrm{\&Sigma;}({\mathrm{SOC}}_i-{\mathrm{SOC}}_i^{\min })$

Step 6.2.2), by each automobile charge-discharge electric power P _icompare with maximum charge-discharge electric power, if out-of-limit, then make P _i=maximum charge-discharge electric power, gets rid of this numbering, by P simultaneously in N _sumaccumulative automobile reaches the power total value of maximum charge-discharge electric power;

Step 6.2.3), according to formula P _r=P _r-P _sum, obtain new P _r;

Step 6.2.4), the P newly obtained _rin new N, circulate above-mentioned process, until distributed to V2G to greatest extent;

Step 6.2.5), to each automobile transmit power command;

Step 6.3), if the frequency modulation frequency modulation power P of electric automobile _{2, i}be greater than maximum charge-discharge electric power, make P _{2, i}after=maximum charge-discharge electric power, then export frequency modulation frequency modulation power P _{2, i}; Otherwise, directly export P _{2, i};

Step 6.4), first after getting mains frequency skew, formulate electric automobile charge-discharge electric power P according to droop control principle _i,k, wherein sagging coefficient gets maximum, then calculates the charge power P of electric automobile _i ^c, according to above-mentioned result of calculation, obtain the primary frequency modulation power P of electric automobile _{1, i}

P _1,i＝P _i,k+P _i ^c

If the primary frequency modulation power P of electric automobile _{1, i}be greater than maximum charge-discharge electric power, make P _{1, i}after=maximum charge-discharge electric power, then export primary frequency modulation power P _{1, i}; Otherwise, directly export P _{1, i};

Step 6.5), the SOC information of inquiry electric automobile, if electric automobile is in the process participating in frequency modulation frequency modulation, SOC value <0.6, is now switched to primary frequency modulation pattern; If electric automobile is in the process participating in primary frequency modulation, SOC value >0.6, is now switched to frequency modulation frequency modulation pattern;

Step 7), detection system frequency, if system frequency is recovered, then exits frequency modulation; Otherwise repetition above-mentioned steps, until system frequency is recovered.

2. a kind of electric automobile dispersion according to claim 1 networks and participates in the control method of electric power system frequency modulation, it is characterized in that, described V2G control centre is: electric automobile is divided into multiple region, a V2G control centre is provided with in each region, accepted the frequency modulation task of power-management centre by described V2G control centre, then meritorious adjustment task is prorated to the electric automobile in administrative area.

3. a kind of electric automobile dispersion according to claim 1 networks and participates in the control method of electric power system frequency modulation, it is characterized in that, is describedly specially with droop control method under mode transfer formula:

Work as SOC _i ^min≤ SOC _i,k≤ SOC _i ⁱⁿ, $a=\sqrt{\frac{{\mathrm{SOC}}_{i,k}-{\mathrm{SOC}}_i^{\mathrm{in}}}{{\mathrm{SOC}}_i^{\min }-{\mathrm{SOC}}_i^{\mathrm{in}}}}$ Time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+a)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-a)\end{array}\right.$

Work as SOC _i ⁱⁿ≤ SOC _i,k≤ SOC _i ^max, $b=\sqrt{\frac{{\mathrm{SOC}}_{i,k}-{\mathrm{SOC}}_i^{\mathrm{in}}}{{\mathrm{SOC}}_i^{\max }-{\mathrm{SOC}}_i^{\mathrm{in}}}}$ Time:

$\left\{\begin{array}{c}{K}_{i,k}^c=\frac{1}{2}{K}_{max}(1+b)\\ K_{i,k}^d=\frac{1}{2}{K}_{max}(1-b)\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^mintime:

$\left\{\begin{array}{c}{K}_{i,k}^c=K_{max}\\ K_{i,k}^d=0\end{array}\right.$

Work as SOC _i,k≤ SOC _i ^maxtime:

$\left\{\begin{array}{c}{K}_{i,k}^c=0\\ K_{i,k}^d=K_{max}\end{array}\right.$

In above-mentioned formula, SOC _i,kfor the state-of-charge of k moment i-th batteries of electric automobile; SOC _i ^minbe that i-th electric automobile allows minimum state-of-charge; SOC _i ^maxbe that i-th electric automobile allows maximum state-of-charge; SOC _i ⁱⁿit is the initial state-of-charge of i-th electric automobile; K _maxfor the sagging coefficient of maximum charge/discharge; K ^c _i,kbe i-th electric automobile, charge sagging coefficient in the k moment; K ^d _i,kbe i-th electric automobile, discharge sagging coefficient in the k moment.