CN114678895A - Electric vehicle cluster cooperative frequency modulation control method and device for power system interconnection area - Google Patents

Electric vehicle cluster cooperative frequency modulation control method and device for power system interconnection area Download PDF

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CN114678895A
CN114678895A CN202210414281.XA CN202210414281A CN114678895A CN 114678895 A CN114678895 A CN 114678895A CN 202210414281 A CN202210414281 A CN 202210414281A CN 114678895 A CN114678895 A CN 114678895A
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frequency
region
power
frequency modulation
power system
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CN114678895B (en
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王明深
易文飞
李娟�
陈实
叶志刚
杨毅
袁晓冬
卜强生
高磊
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State Grid Jiangsu Electric Power Co Ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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State Grid Jiangsu Electric Power Co Ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power 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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H02J3/322—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means the battery being on-board an electric or hybrid vehicle, e.g. vehicle to grid arrangements [V2G], power aggregation, use of the battery for network load balancing, coordinated or cooperative battery charging
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • 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
    • H02J2300/40—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously

Abstract

The invention discloses an electric vehicle cluster cooperative frequency modulation control method and device for an interconnected region of a power system. Secondly, defining a concept of frequency modulation depth, and quickly estimating a frequency conversion control coefficient of the electric automobile cluster participating in primary frequency modulation according to the obtained frequency response parameter and the obtained frequency modulation depth. And finally, calculating the power of the electric automobile clusters in each region according to the frequency conversion control coefficient of the electric automobile clusters participating in primary frequency modulation in the primary frequency modulation, and performing cooperative control on the electric automobile clusters. The invention solves the problem of waste of inter-area electric automobile cluster response capacity and improves the frequency stability of the power system.

Description

Electric vehicle cluster cooperative frequency modulation control method and device for power system interconnection area
Technical Field
The invention relates to a power system interconnection area-oriented electric vehicle cluster cooperative frequency modulation control method and device, and belongs to the technical field of power system operation control.
Background
With the access of high-proportion renewable new energy to the power grid, problems such as unbalanced distribution of new energy and the like can bring huge challenges to the frequency modulation aspect of the inter-regional power system. China vigorously propels new energy electric vehicles, and the estimated reserved quantity is 7500 thousands of vehicles by 2030. Considering the rapid growth of electric vehicles and the charge-discharge characteristics of batteries, great potential is provided for participating in the frequency fluctuation problem in power systems. The electric automobile control system can communicate with the electric automobile through equipment such as instrument equipment, a power electronic interface, an energy converter and a two-way communication interface, so that a large number of connected electric automobiles can be effectively controlled. Frequency deviation is traditionally controlled by coordinating the output power of multiple generator sets. However, the frequency fluctuation caused by the access of a high proportion of new energy to the power grid is difficult to meet the demand of supply and demand balance only by the traditional generator set. The access of the electric automobile can assist the generator set to control the problem of frequency fluctuation. However, when a current large number of electric vehicles are connected to a power grid and participate in frequency modulation of a power system, in the aspect of determining a frequency conversion control coefficient when an electric vehicle cluster participates in primary frequency modulation, differences of different frequency modulation depths and frequency response parameters between regions cannot be considered comprehensively, resource waste is easily caused, and great challenges are brought to the frequency safety and stability of the power system. Meanwhile, a cooperative control strategy that an electric vehicle cluster based on two interconnected power systems participates in primary frequency modulation is also lacked.
Disclosure of Invention
The invention aims to provide a power system interconnection area-oriented electric vehicle cluster cooperative frequency modulation control method and device, which are used for estimating a frequency conversion control coefficient when an electric vehicle cluster participates in primary frequency modulation according to predicted frequency response parameters and different frequency modulation depths among areas, comprehensively considering the different frequency modulation depths of the electric vehicle cluster among the areas, obtaining a cooperative control strategy based on the participation of the electric vehicle cluster among the areas in the primary frequency modulation, solving the problem of waste of the response capacity of the electric vehicle cluster among the areas and improving the frequency stability of a power system.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides an electric vehicle cluster cooperative frequency modulation control method for an electric power system interconnection area, which comprises the following steps:
calculating frequency response functions of all regions under the condition of load disturbance according to the simplified model of the primary frequency modulation of the power system among the regions, and calculating the maximum value and the minimum value of frequency deviation of all the regions based on the frequency response functions;
calculating a frequency conversion control coefficient of each regional electric automobile cluster participating in primary frequency modulation based on the maximum frequency deviation value, the minimum frequency deviation value and the frequency modulation depth of each region;
and calculating the power of the electric automobile clusters in each region according to the frequency conversion control coefficient of the electric automobile clusters participating in primary frequency modulation in the primary frequency modulation, and performing cooperative control on the electric automobile clusters.
Further, the calculating a frequency response function of each region under the condition of load disturbance according to the simplified model of the primary frequency modulation of the inter-region power system includes:
obtaining a tie-line power increment delta P according to a simplified model of primary frequency modulation of an inter-area power systemt12Expressed as:
Figure BDA0003604833100000021
wherein, Δ f1(s) and Δ f2(s) are frequency deviations in frequency domains in the region 1 and the region 2 respectively, T is a tie line synchronization coefficient, and s is a Laplace operator;
disturbance power of each area under the condition of load disturbance is expressed as follows:
Figure BDA0003604833100000022
wherein, Δ Pdi(s) is the disturbance power in the frequency domain in region i, i ═ 1,2, Pstep,iIs the magnitude of the step function in region i;
the generator output power in the frequency domain of each region is expressed as:
Figure BDA0003604833100000023
wherein, Δ PGi(s) Generator output Power in frequency Domain in region i, Δ fi(s) is the frequency deviation in the frequency domain in region i, RiDifferential coefficient of governor for region i, KmiIs the mechanical power gain coefficient of region i, FHiHigh pressure turbine scaling factor, T, for region iRiIs a reheat time constant of region i, HiGenerator inertial time constant for region i, DiIs a regioni load damping coefficient, Δ P1(s) and Δ P2(s) power increments in the frequency domain in zone 1 and zone 2, respectively, are expressed as:
Figure BDA0003604833100000024
simultaneous derivation is performed to obtain a frequency response function representation of each region as:
Figure BDA0003604833100000025
Figure BDA0003604833100000026
Figure BDA0003604833100000031
further, the calculating the maximum frequency deviation value and the minimum frequency deviation value of each region based on the frequency response function includes:
substituting all known parameters into the frequency response function, simultaneously omitting low-order terms, and carrying out inverse Laplace transformation to obtain delta fi(t),i＝1,2；
The derivative of the frequency response curve is made zero to obtain the time t reaching the lowest point of the frequencynadir,i,i＝1,2；
Will reach the time t of the lowest frequency pointnadir,iSubstitution of the value of (d) into Δ fi(t) obtaining a lowest frequency point fnadir,i,i＝1,2；
Let t → ∞ obtain the steady-state frequency fss,i,i＝1,2；
The maximum and minimum frequency deviation values for each region are calculated as follows:
Δfmax,i＝|fnadir,i-0|；
Δfmin,i＝|fnadir,i-fss,i|；
wherein, Δ fmax,iAnd Δ fmin,iThe maximum and minimum frequency deviations for region i, respectively.
Further, the calculating a frequency conversion control coefficient of each regional electric vehicle cluster participating in primary frequency modulation based on the maximum frequency deviation value, the minimum frequency deviation value and the frequency modulation depth of each region includes:
Figure BDA0003604833100000032
Figure BDA0003604833100000033
wherein, KEVIs a frequency conversion control coefficient, sigma is the frequency modulation depth of the electric automobile cluster, and delta fmaxIs the maximum value of the frequency deviation, Δ fminIs the minimum value of frequency deviation, fbaseIs a reference frequency, PbaseIs the reference power.
Further, the calculating the cluster power of the electric vehicles in each area includes:
Figure BDA0003604833100000034
wherein, PEVFor clustering power, T, of electric vehiclesEVThe time response constant is controlled in the charging and discharging process.
The invention also provides an electric vehicle cluster cooperative frequency modulation control device facing the power system interconnection area, which comprises:
the first calculation module is used for calculating frequency response functions of all regions under the condition of load disturbance according to the simplified model of the primary frequency modulation of the power system among the regions, and calculating the maximum value and the minimum value of frequency deviation of all the regions based on the frequency response functions;
the second calculation module is used for calculating the frequency conversion control coefficient of each regional electric automobile cluster participating in primary frequency modulation based on the frequency deviation maximum value, the frequency deviation minimum value and the frequency modulation depth of each region;
and the number of the first and second groups,
and the control module is used for calculating the cluster power of the electric automobiles in each region according to the electric automobile cluster control model of the primary frequency modulation based on the frequency conversion control coefficient of the electric automobile clusters participating in the primary frequency modulation in each region, and performing cooperative control on the electric automobile clusters.
Further, the first calculating module is specifically configured to:
obtaining the power increment delta P of the tie line according to the simplified model of the primary frequency modulation of the inter-area power systemt12：
Figure BDA0003604833100000041
Wherein, Δ f1(s) and Δ f2(s) are frequency deviations in frequency domains in the region 1 and the region 2 respectively, T is a tie line synchronization coefficient, and s is a Laplace operator;
disturbance power of each area under the condition of load disturbance is expressed as follows:
Figure BDA0003604833100000042
wherein, Δ Pdi(s) is the disturbance power in the frequency domain in region i, i ═ 1,2, Pstep,iIs the magnitude of the step function in region i;
the generator output power in the frequency domain of each region is expressed as:
Figure BDA0003604833100000043
wherein, Δ PGi(s) Generator output Power in frequency Domain in region i, Δ fi(s) is the frequency deviation in the frequency domain in region i, RiDifferential coefficient of governor for region i, KmiIs the mechanical power gain coefficient of region i, FHiHigh pressure turbine scaling factor, T, for region iRiIs a regioni reheat time constant, HiGenerator inertial time constant for region i, DiLoad damping coefficient, Δ P, for region i1(s) and Δ P2(s) power increments in the frequency domain in zone 1 and zone 2, respectively, are expressed as:
Figure BDA0003604833100000044
simultaneous derivation is performed to obtain a frequency response function representation of each region as:
Figure BDA0003604833100000051
Figure BDA0003604833100000052
Figure BDA0003604833100000053
substituting all known parameters into the frequency response function, simultaneously omitting low-order terms, and carrying out inverse Laplace transformation to obtain delta fi(t),i＝1,2；
The derivative of the frequency response curve is made zero to obtain the time t reaching the lowest point of the frequencynadir,i,i＝1,2；
Will reach the frequency minimum time tnadir,iSubstituting the value of (d) into Δ fi(t) obtaining a lowest frequency point fnadir,i,i＝1,2；
Let t → ∞ obtain the steady-state frequency fss,i,i＝1,2；
The maximum and minimum frequency deviation values for each region are calculated as follows:
Δfmax,i＝|fnadir,i-0|；
Δfmin,i＝|fnadir,i-fss,i|；
wherein, Δ fmax,iAnd Δ fmin,iThe maximum and minimum frequency deviations for region i, respectively.
Further, the second calculation module is specifically configured to,
calculating the frequency conversion control coefficient as follows:
Figure BDA0003604833100000054
Figure BDA0003604833100000055
wherein, KEVIs a frequency conversion control coefficient, sigma is the frequency modulation depth of the electric automobile cluster, and delta fmaxIs the maximum value of the frequency deviation, Δ fminIs the minimum value of frequency deviation, fbaseIs a reference frequency, PbaseIs the reference power.
Further, the control module is specifically configured to,
calculating the cluster power of the electric automobiles in each area as follows:
Figure BDA0003604833100000061
wherein, PEVFor clustering power, T, of electric vehiclesEVThe time response constant is controlled in the charging and discharging process.
The invention achieves the following beneficial effects:
the invention provides an electric vehicle cluster cooperative frequency modulation control method facing an interconnected region of a power system, and provides an analytic method for rapidly predicting frequency response parameters according to a simplified inter-region traditional generator set frequency modulation model; rapidly estimating a frequency conversion control coefficient of the electric automobile cluster participating in primary frequency modulation according to the obtained frequency response parameter and the frequency modulation depth; and finally, performing cooperative control of primary frequency modulation. Simulation results show that frequency fluctuation caused by load disturbance is within an allowable range, and compared with the condition that no electric vehicle participates in system frequency modulation, the frequency deviation is obviously reduced under the condition that the electric vehicle participates in the system frequency modulation, and the response time is obviously reduced. When the inter-area electric automobile cluster coordination control strategy is considered, the frequency deviation and the response time are reduced more obviously in the system. Meanwhile, the overshoot of the frequency response is reduced, and the stability of the power system is improved.
Drawings
FIG. 1 is a schematic diagram of a primary frequency modulation model of a conventional two-region power system;
FIG. 2 is a simplified schematic diagram of a primary frequency modulation model of the regional power system of FIG. 1;
FIG. 3 is a schematic diagram of frequency nadir prediction;
FIG. 4 is a model of a primary frequency modulation first-order inertia link of the electric automobile participation system;
fig. 5 is a schematic primary frequency modulation diagram of an inter-area electric vehicle cluster participation system according to an embodiment of the present invention;
FIG. 6 is a frequency response for three scenarios in region A according to an embodiment of the present invention;
fig. 7 shows frequency responses in three scenarios in the area B according to the embodiment of the present invention.
Detailed Description
The invention is further described below. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The embodiment of the invention provides an electric vehicle cluster cooperative frequency modulation control method for an interconnected region of a power system, which comprises the following specific implementation processes:
1) predicting frequency response parameter of primary frequency modulation of inter-domain electric power system
When the system frequency fluctuation is small or the grid frequency is operated near the rated value, the dynamic characteristic of the system can be described by using a linear model. A conventional two-zone power system primary frequency modulation model is shown in fig. 1. Each region detects the frequency deviation signal delta f and the exchange power error signal of the connecting line at any moment, amplifies, mixes and converts the error signals into active power control signals and sends the active power control signals to the generator to obtain a torque variable, and the prime motor brings the output power change of the generator, thereby changing the active balance of the system and adjusting the frequency to keep the frequency within an allowable range (+/-0.2 to +/-0.5 Hz).
The system frequency response model only considers frequencies related to shaft speed changes, for which reason turbine response is neglected to be too slow and generator response too fast, so that a simplified system consisting of a speed-regulated servo motor, a steam turbine and an inertia module can be obtained. The most significant constant in this system is the reheat time constant TRIts value is typically 6-8(s) and tends to dominate most of the response of the output power. Thus, T isRThe smaller time constant compared to the phase is negligible. The second dominant time constant in the system is the inertial time constant H, which is typically 3-6(s) for atypical large units and always doubles, increasing its impact in the system. The third dominant time constant in the system is R, i.e. the governor slack adjuster constant, which plays a role of gain in control. Therefore, the primary frequency model of the conventional two-region power system can be simplified as shown in fig. 2.
The frequency nadir prediction is shown in fig. 3.
Calculating the Laplace transform of a frequency response function according to the simplified model of the primary frequency modulation of the power system between the areas as follows:
first, the tie line power increment Δ Pt12Can be expressed as:
Figure BDA0003604833100000071
in the formula,. DELTA.f1(s) and Δ f2(s) are frequency deviations in the frequency domain in region 1 and region 2, respectively.
For sudden load disturbances, consider the form of a step function, namely:
ΔPdi(t)＝Pstep,i·u(t) (2)
in the formula,. DELTA.Pdi(t) is the power of the disturbance in the time domain in region i (i 1,2), Pstep,iThe amplitude of the step function in the region i (i ═ 1,2) and u (t) are step functions.
Carrying out Laeulas transformation on the formula (3):
Figure BDA0003604833100000072
region 1 and region 2 may be represented by formula (4) and formula (5):
Figure BDA0003604833100000073
in the formula,. DELTA.PGi(s) is the generator output power in the frequency domain, Δ f, in region i (i ═ 1,2)iThe(s) is a frequency deviation in the frequency domain in the region i (i ═ 1,2), and other parameters are shown in table 1.
Figure BDA0003604833100000074
In the formula,. DELTA.P1(s) and Δ P2(s) power increments in the frequency domain in zone 1 and zone 2, respectively.
Therefore, Δ f can be derived1(s) and Δ f2(s) as shown in formula (6) and formula (7), respectively:
Figure BDA0003604833100000081
Figure BDA0003604833100000082
wherein, pi, omega and phi are respectively polynomial expressions containing s, which are shown as the following formula,
Figure BDA0003604833100000083
in the formula, the values of the respective parameters are shown in Table 1:
TABLE 1 values of parameters of conventional power systems
Figure BDA0003604833100000084
By substituting each parameter in table 1 for equations (6) and (7) and combining equation (5) while omitting the low-order terms, the frequency response function in each region can be obtained as follows:
Figure BDA0003604833100000085
Figure BDA0003604833100000086
wherein, b1＝2.937，b2＝7.256，b3＝10.41，b4＝8.739，a1＝31.5，a2＝117.1，a3＝285.8， a4＝476.1，a5＝487.1，a6＝279.7；n1＝0.04037，n2＝0.1965，n3＝0.3151，n4＝0.3501， m1＝0.1929，m2＝1.931，m3＝7.982，m4＝20.09，m5＝26.96，m6＝21.01。
Inverse Laplace transform of the above formula is carried out to obtain delta fi(t) (i ═ 1,2), and the delay time of the step function is set to t0Let d Δ f be 1(s) since at the lowest point of the frequency, the derivative of the frequency response curve is zeroi(t)/dt is 0(i is 1,2), and the time to reach the lowest frequency point t can be obtainednadir,i(i is 1,2), and converting tnadir,iSubstituting the value of (i-1, 2) into Δ fi(t) (i is 1,2) the lowest frequency point f can be determinednadir,i(i → 1,2), and when t → ∞ then f can be determinedss,i(i ═ 1, 2). Therefore, three time domain frequency parameters in the region i (i ═ 1,2) can be obtained, as shown in table 2.
TABLE 2 inter-region frequency response time domain index parameter values
Figure BDA0003604833100000091
2) Predicting primary frequency modulation frequency conversion control coefficient of electric automobile cluster participating inter-regional system
The control model for the primary frequency modulation electric vehicle comprises a variable frequency control coefficient and a control time response constant, and a transfer function for reflecting power is shown as the following formula (11),
Figure BDA0003604833100000092
wherein, KEVFor variable frequency control coefficients, TEVIn order to control the time response constant in the charging and discharging process, the value is generally smaller. PEVAnd clustering power for the electric automobile.
The primary frequency modulation control model of the electric automobile participation system is shown in figure 4. The primary frequency modulation and frequency conversion control coefficient of the electric automobile is determined by the power grid dispatching center according to the frequency fluctuation upper and lower limit values of the electric automobile participating in frequency modulation, the number of controllable electric automobiles, the reference frequency, the reference power and the frequency modulation depth of the electric automobile cluster, and can be expressed as follows:
Figure BDA0003604833100000093
wherein, sigma is the frequency modulation depth of the electric automobile cluster, and delta fmaxIs the maximum value of the frequency deviation, Δ fminIs the minimum value of frequency deviation, fbaseIs a reference frequency, PbaseIs the reference power.
ΔfmaxAnd Δ fminThe expression of (a) is as follows:
Δfmax＝|fnadir-0| (13)
Δfmin＝|fnadir-fss| (14)
the frequency modulation depth sigma refers to the sum of adjustable capacities of electric automobile clusters between areas, and is shown as the following formula:
Figure BDA0003604833100000101
in the formula, PEV,iCharging power for the ith electric automobile, wherein N is the number of the controllable electric automobiles in the region.
3) Primary frequency modulation control strategy for establishing electric vehicle inter-participating region system
A schematic diagram of the inter-area electric automobile cluster participation system primary frequency modulation is shown in FIG. 5.
The running state in the power system is monitored in real time by a power grid dispatching center, and the electric vehicle cluster control center collects and stores dynamic information of electric vehicles, including information such as the upper and lower limits of available electric quantity and dispatchable time of each charging station. Meanwhile, the cluster control center feeds the information back to the power system dispatching center. Considering the difference of the frequency modulation depth of each region, when disturbance occurs in the system, the power system dispatching center allocates different adjusting tasks to each region according to the difference of the frequency modulation depth of each region and the adjusting capacity of the generator set, so that cooperative control among the regions is realized, and the condition that the safety and the stability of the power system are influenced due to the fact that the adjusting task of a certain region is too heavy is avoided. The specific process is as follows:
the electric power system dispatching center firstly calculates the frequency modulation depth of each region according to the information fed back by the electric automobile cluster. And secondly, considering the disturbed condition, and according to the predicted time domain frequency index of each region, further calculating to obtain the maximum value and the minimum value of the frequency deviation of each region, thereby obtaining the variable frequency control coefficient of each region electric automobile cluster participating in primary frequency modulation. And finally, calculating the cluster power of the electric automobiles in each area according to the electric automobile cluster model.
The invention sets three scenes, which are respectively as follows: s1, the motorcar cluster does not participate in frequency modulation. S2, the electric automobile cluster is existed but no cooperative control strategy participates in frequency modulation. S3 has electric automobile cluster and has cooperative control strategy to participate in frequency modulation. Assuming that the number of controllable electric vehicles in the region a is 10 thousands, the reference power is 300MW, the number of controllable electric vehicles in the region B is 12 thousands, the reference power is 350MW, the reference frequency of both regions is 50Hz, and the charging capacity of the single electric vehicle is 6.6 kW. Assuming that the delay time τ follows a normal distribution τ N [1,2] s, regions a and B are given perturbations of-0.25 MW and-0.2 MW, respectively, at t ═ 1 s. The frequency response simulation results for three scenarios in each area are shown in fig. 6 and 7.
As can be seen from fig. 6 and 7, the frequency fluctuation caused by the load disturbance is within the allowable range, and compared with the frequency modulation without the electric vehicle participating in the system frequency modulation, the frequency deviation is significantly reduced and the response time is significantly reduced in the case of the electric vehicle participating in the system frequency modulation. The maximum frequency deviation is respectively reduced by 4.9% and 5.3% when the electric vehicle participates. However, when the inter-area electric vehicle cluster coordination control strategy is considered, the frequency deviation and the response time in the system are reduced more obviously. And the overshoot of the frequency response is reduced. The stability of the power system is improved, and meanwhile, the effectiveness of the provided cooperative control strategy is verified.
It is to be noted that the apparatus embodiment corresponds to the method embodiment, and the implementation manners of the method embodiment are all applicable to the apparatus embodiment and can achieve the same or similar technical effects, so that the details are not described herein.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (9)

1. An electric vehicle cluster cooperative frequency modulation control method for an electric power system interconnection area is characterized by comprising the following steps:
calculating frequency response functions of all regions under the condition of load disturbance according to the simplified model of the primary frequency modulation of the power system among the regions, and calculating the maximum value and the minimum value of frequency deviation of all the regions based on the frequency response functions;
calculating a frequency conversion control coefficient of each regional electric automobile cluster participating in primary frequency modulation based on the maximum frequency deviation value, the minimum frequency deviation value and the frequency modulation depth of each region;
and calculating the power of the electric automobile clusters in each region according to the frequency conversion control coefficient of the electric automobile clusters participating in primary frequency modulation in the primary frequency modulation, and performing cooperative control on the electric automobile clusters.
2. The electric vehicle cluster cooperative frequency modulation control method facing the interconnected region of the power system as recited in claim 1, wherein the calculating the frequency response function of each region under the condition of load disturbance according to the simplified model of primary frequency modulation of the power system between the regions comprises:
obtaining the power increment delta P of the tie line according to the simplified model of the primary frequency modulation of the inter-area power systemt12Expressed as:
Figure FDA0003604833090000011
wherein, Δ f1(s) and Δ f2(s) frequency deviation in the frequency domain in region 1 and region 2, respectively, T is a tie line synchronization coefficient, and s is a Laplace operator;
disturbance power of each area under the condition of load disturbance is expressed as follows:
Figure FDA0003604833090000012
wherein, Δ Pdi(s) is the disturbance power in the frequency domain in region i, i ═ 1,2, Pstep,iIs the magnitude of the step function in region i;
the generator output power in the frequency domain of each region is expressed as:
Figure FDA0003604833090000013
wherein, Δ PGi(s) Generator output Power in frequency Domain in region i, Δ fi(s) is the frequency deviation in the frequency domain in region i, RiDifferential speed governor coefficient of zone i, KmiIs the mechanical power gain coefficient of region i, FHiHigh pressure turbine scaling factor, T, for region iRiIs a reheat time constant of region i, HiGenerator inertial time constant for region i, DiLoad damping coefficient, Δ P, for region i1(s) and Δ P2(s) power increase in the frequency domain in zone 1 and zone 2, respectively, expressed as:
Figure FDA0003604833090000021
simultaneous derivation is performed to obtain a frequency response function representation of each region as:
Figure FDA0003604833090000022
Figure FDA0003604833090000023
Figure FDA0003604833090000024
3. the electric vehicle cluster cooperative frequency modulation control method facing the interconnected region of the power system as claimed in claim 2, wherein the calculating of the maximum frequency deviation value and the minimum frequency deviation value of each region based on the frequency response function comprises:
substituting each known parameter into the frequency response function while omitting low-order terms, andinverse Laplace transform is performed to obtain Δ fi(t),i＝1,2；
The derivative of the frequency response curve is made zero to obtain the time t reaching the lowest point of the frequencynadir,i,i＝1,2；
Will reach the frequency minimum time tnadir,iSubstituting the value of (d) into Δ fi(t) obtaining a frequency minimum fnadir,i,i＝1,2；
Let t → ∞ obtain the steady-state frequency fss,i,i＝1,2；
The maximum and minimum frequency deviation values for each region are calculated as follows:
Δfmax,i＝|fnadir,i-0|；
Δfmin,i＝|fnadir,i-fss,i|；
wherein, Δ fmax,iAnd Δ fmin,iThe maximum and minimum frequency deviations for region i, respectively.
4. The electric vehicle cluster cooperative frequency modulation control method facing the interconnected region of the power system as claimed in claim 3, wherein the calculating of the frequency conversion control coefficient of each regional electric vehicle cluster participating in the primary frequency modulation based on the maximum frequency deviation value, the minimum frequency deviation value and the frequency modulation depth of each region comprises:
Figure FDA0003604833090000031
Figure FDA0003604833090000032
wherein, KEVIs a frequency conversion control coefficient, sigma is the frequency modulation depth of the electric automobile cluster, and delta fmaxIs the maximum value of the frequency deviation, Δ fminIs the minimum value of frequency deviation, fbaseIs a reference frequency, PbaseIs the reference power.
5. The electric vehicle cluster cooperative frequency modulation control method for the interconnected region of the power system as claimed in claim 4, wherein the calculating of the electric vehicle cluster power of each region comprises:
Figure FDA0003604833090000033
wherein, PEVFor clustering power, T, of electric vehiclesEVThe time response constant is controlled in the charging and discharging process.
6. The utility model provides an electric automobile cluster is frequency modulation controlling means in coordination towards electric power system interconnection region which characterized in that includes:
the first calculation module is used for calculating frequency response functions of all regions under the condition of load disturbance according to the simplified model of the primary frequency modulation of the power system among the regions, and calculating the maximum value and the minimum value of frequency deviation of all the regions based on the frequency response functions;
the second calculation module is used for calculating the frequency conversion control coefficient of each regional electric automobile cluster participating in primary frequency modulation based on the maximum frequency deviation value, the minimum frequency deviation value and the frequency modulation depth of each region;
and the number of the first and second groups,
and the control module is used for calculating the cluster power of the electric automobiles in each region according to the electric automobile cluster control model of the primary frequency modulation based on the frequency conversion control coefficient of the electric automobile clusters participating in the primary frequency modulation in each region, and performing cooperative control on the electric automobile clusters.
7. The electric vehicle cluster cooperative frequency modulation control device for the power system interconnection area as recited in claim 6, wherein the first computing module is specifically configured to:
obtaining the power increment delta P of the tie line according to the simplified model of the primary frequency modulation of the inter-area power systemt12：
Figure FDA0003604833090000034
Wherein, Δ f1(s) and Δ f2(s) are frequency deviations in frequency domains in the region 1 and the region 2 respectively, T is a tie line synchronization coefficient, and s is a Laplace operator;
disturbance power of each area under the condition of load disturbance is expressed as follows:
Figure FDA0003604833090000035
wherein, Δ Pdi(s) is the disturbance power in the frequency domain in region i, i ═ 1,2, Pstep,iIs the magnitude of the step function in region i;
the generator output power in the frequency domain of each region is expressed as:
Figure FDA0003604833090000041
wherein, Δ PGi(s) Generator output Power in the intermediate frequency Domain in region i, Δ fi(s) is the frequency deviation in the frequency domain in region i, RiDifferential coefficient of governor for region i, KmiIs the mechanical power gain coefficient of region i, FHiHigh pressure turbine scaling factor, T, for region iRiIs a reheat time constant of region i, HiGenerator inertial time constant for region i, DiLoad damping coefficient, Δ P, for region i1(s) and Δ P2(s) power increments in the frequency domain in zone 1 and zone 2, respectively, are expressed as:
Figure FDA0003604833090000042
simultaneous derivation is performed to obtain a frequency response function representation of each region as:
Figure FDA0003604833090000043
Figure FDA0003604833090000044
Figure FDA0003604833090000045
substituting all known parameters into the frequency response function, simultaneously neglecting low-order terms, and performing inverse Laplace transform to obtain delta fi(t),i＝1,2；
The derivative of the frequency response curve is made zero to obtain the time t reaching the lowest point of the frequencynadir,i,i＝1,2；
Will reach the frequency minimum time tnadir,iSubstitution of the value of (d) into Δ fi(t) obtaining a lowest frequency point fnadir,i,i＝1,2；
Let t → ∞ obtain the steady-state frequency fss,i,i＝1,2；
The maximum and minimum frequency deviation values for each region are calculated as follows:
Δfmax,i＝|fnadir,i-0|；
Δfmin,i＝|fnadir,i-fss,i|；
wherein, Δ fmax,iAnd Δ fmin,iThe maximum and minimum frequency deviation values of the region i, respectively.
8. The electric vehicle cluster cooperative frequency modulation control device for the interconnected region of the power system as claimed in claim 7, wherein the second computing module is specifically configured to,
calculating the frequency conversion control coefficient as follows:
Figure FDA0003604833090000051
Figure FDA0003604833090000052
wherein, KEVIs a frequency conversion control coefficient, sigma is the frequency modulation depth of the electric automobile cluster, and delta fmaxIs the maximum value of the frequency deviation, Δ fminIs the minimum value of frequency deviation, fbaseIs a reference frequency, PbaseIs the reference power.
9. The electric vehicle cluster cooperative frequency modulation control device for the interconnected region of the power system as claimed in claim 8, wherein the control module is specifically configured to,
calculating the cluster power of the electric automobiles in each area as follows:
Figure FDA0003604833090000053
wherein, PEVFor clustering power, T, of electric vehiclesEVThe time response constant is controlled in the charging and discharging process.
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