CN110137981B - Distributed energy storage aggregator AGC method based on consistency algorithm - Google Patents
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Abstract
The invention discloses a distributed energy storage aggregator AGC method based on a consistency algorithm, and belongs to the technical field of power generation with energy storage participating in power grid frequency modulation. The AGC signals are primarily distributed through a filtering link; the aggregator integrates distributed energy storage into a whole to participate in AGC, tracks frequency modulation signals outwards and internally controls frequency modulation output of energy storage with different technical characteristics; an energy storage frequency modulation cost function established according to the energy storage technical characteristic parameters and the real-time electric quantity is used as a key index for distributing each energy storage frequency modulation output; and performing local calculation on the distributed energy storage through exchanging consistency variables with adjacent energy storage by using a multi-agent consistency algorithm in the aggregator to obtain an optimized energy storage output scheme. The method is used for integrated control of the distributed energy storage of various types, small scale and modularization, so that the distributed energy storage meets the minimum access capacity requirement of an AGC market, the frequency modulation capability of a power grid is effectively improved, and the service life of the energy storage is prolonged while the advantage of quick response of the energy storage is exerted.
Description
Technical Field
The invention discloses a distributed energy storage aggregator AGC method based on a consistency algorithm, and belongs to the technical field of power generation with energy storage participating in power grid frequency modulation.
Background
The replacement of fossil energy by renewable energy is an important means for fundamentally solving the problems of global energy shortage, environmental pollution, climate change and the like, and therefore, renewable energy power generation becomes the core of energy development strategies of various countries. By the end of 2016, the installed capacities of global wind power generation and photovoltaic power generation are 467GW and 296GW respectively, and the installed capacities of wind power generation and photovoltaic power generation in China are the first in the world. However, most renewable energy sources such as wind power generation and photovoltaic power generation are intermittent energy sources, output has fluctuation and randomness, and large amount of grid connection causes active imbalance and inertia reduction of a power grid, so that frequency instability of a power system is caused.
The energy storage participation AGC (Automatic Generation Control) has the advantages of high response speed, high Control precision, bidirectional adjustment and the like, and can effectively improve the frequency modulation capability of a power grid. In the future, a large amount of distributed energy storage exists on a distributed power supply side, a distribution network side and a user side, and the distributed energy storage system has the characteristics of small capacity, large quantity, scattered layout, large performance difference, high single-machine access cost, poor controllability and the like. To achieve the minimum admission capacity requirement of the AGC market, it is necessary to aggregate multiple distributed energy storages with an aggregator. Compared with a centralized energy storage power station, the integrated distributed energy storage is beneficial to preventing 'N-1' failure and solving the problems of installation site limitation and the like, reduces the line loss and the investment pressure, and has higher economical efficiency in AGC participation.
Distributed energy storage participates in power grid frequency modulation in the form of an energy aggregator, and the problems of frequency modulation responsibility distribution in a distributed energy storage aggregator group, energy balance of each stored energy in the aggregator, a distributed energy storage control structure and the like need to be solved.
Disclosure of Invention
The invention provides a distributed energy storage aggregator AGC method based on a consistency algorithm, which meets the system frequency modulation requirement with the minimum frequency modulation cost by responding the system AGC externally and controlling the energy storage electric quantity in an internal equalization manner, and solves the technical problem that the distributed energy storage participates in the optimal control of the power grid frequency modulation in the form of an energy aggregator.
In order to achieve the purpose, the invention adopts the following technical scheme to achieve the distributed energy storage aggregator AGC method based on the consistency algorithm.
The filtering link carries out primary distribution on the frequency modulation responsibility of the traditional unit and the stored energy, the aggregator integrates the distributed stored energy into a whole, the frequency modulation signal is tracked outwards, the objective function is distributed for the stored energy frequency modulation output with the minimum cost of all the distributed stored energy frequency modulation costs in the aggregator as the stored energy frequency modulation output, the multi-agent consistency algorithm is adopted to solve the frequency modulation output distribution scheme meeting certain constraints, each distributed stored energy in the aggregator is used as an intelligent agent to carry out information exchange with adjacent stored energy, and local operation is carried out by utilizing self state information and technical characteristics until all the individual consistency variables are approximately the same.
As a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, a filtering link divides a system AGC signal into a low-frequency component and a high-frequency component, and then respectively transmits the low-frequency component and the high-frequency component to a traditional unit and the distributed energy storage aggregator to respond, and the frequency threshold of filtering is determined by the relative size of the climbing capacity of the traditional unit and the capacity of the distributed energy storage aggregator.
As a further optimization scheme of the AGC method of the distributed energy storage aggregator based on the consistency algorithm, the distributed energy storage aggregator concentrates a plurality of distributed energy storages into a whole to participate in AGC in a macroscopic sense so as to store an energy AGC signal PAGC highFor input signals, the output signal is the sum of the output powers P of the energy stored in the aggregatorEA sumThe external control aims to make P as much as possibleEA sumIs close to PAGC highThe internal control objective is to maintain the balance of the respective stored energy quantities.
As a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, the energy storage frequency modulation cost function is as follows:
wherein,
represents the frequency modulation cost of the nth energy storage at the time k, Pn,kRepresenting the output power of the nth stored energy at time k, En,kRepresenting the electric quantity of the nth stored energy at the moment k,
represents the optimum charge level of the nth stored energy, anAnd bnWeights, η, representing the frequency modulation cost due to the power and electric quantity variation of the nth stored energyn cCharging efficiency, η, for the nth stored energyn dFor the charging efficiency of the nth stored energy, Δ t represents the time interval between two frequency modulation controls.
Optimal electric quantity as a further optimization scheme of distributed energy storage aggregator AGC method based on consistency algorithm
The set value of the energy storage capacity can be adjusted according to the condition that the energy storage participates in the power grid service, when the energy storage participates in a plurality of power grid services at the same time, the energy storage capacity can be divided into a frequency modulation service part and 1-a% of other service parts, and then
The set values of (a) are set as:
wherein S isnThe nth capacity to store energy.
As a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, the frequency modulation capacity constraint of the nth energy storage is as follows:
wherein,
and
respectively representing the minimum value and the maximum value of the nth energy storage running power,
and
respectively representing the minimum value and the maximum value of the nth energy storage climbing rate,
and
respectively representing the minimum value and the maximum value of the nth energy storage electric quantity.
As a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, the form of the consistency variable is:
wherein λ isn,kRepresenting the consistency variable of the nth stored energy at time k,
and a quadratic coefficient of the frequency modulation cost function of the nth stored energy in the charging state is represented by the following expression:
wherein,
and a quadratic coefficient of the frequency modulation cost function of the nth stored energy in a discharge state is expressed as follows:
wherein,
the coefficient of the first order of the frequency modulation cost function of the nth stored energy at the moment k and in a charging state is represented by the following expression:
wherein,
table showing the coefficient of the first order of the FM cost function of the nth stored energy at the moment k and in the discharge stateThe expression is as follows:
as a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, the method for performing iterative computation by exchanging consistency variables of adjacent energy storage comprises the following steps:
and correcting a consistency variable in a last iteration result:
and then, carrying out constraint on the consistency variable:
wherein,
for the consistency variable value of j iteration of the nth stored energy at the kth frequency modulation moment, sigma1、σ2And σ3Respectively, are the correction coefficients of the image data,
and the value of the initial value of the frequency modulation output of the nth energy storage at the k moment is as follows:
n is the number of distributed energy storage in the aggregator,
denotes the value of the consistent variable, Ω, without limiting the value rangeλThe consistency variable representing the nth stored energy is advisable to be ranged.
Using uniform changesThe quantity lambda is reversely deduced to obtain a virtual power value
Lambda and
corresponding relation, λ1λ or more2The method comprises the following steps:
λ1<λ2the method comprises the following steps:
wherein λ is1Is the power positive half-axis critical point, λ2Is the power negative half-shaft critical point,
indicating after redefining the special interval
Representative function fλThe inverse of (c), noted:
and correcting the virtual power value:
and then, constraining the power value:
wherein omegaERepresenting the range of adjustment capability of each energy storage unit.
As a further optimization scheme of the distributed energy storage aggregator AGC method based on the consistency algorithm, a communication topology with each energy storage connection degree larger than 2 is adopted, and normal operation can be guaranteed when a fault occurs in an individual communication line.
By adopting the technical scheme, the invention has the following beneficial effects:
(1) according to the invention, a power supply side, a distribution network side and a user side are integrated into a large number of distributed energy storages with small capacity, distributed layout and difficult regulation and control through the aggregator as high-quality frequency modulation resources capable of receiving unified scheduling, so that the distributed energy storages can meet the minimum access capacity requirement of an AGC market, frequency modulation signals are responded to the outside quickly, management and control of energy storage are realized by utilizing a consistency algorithm in the aggregator, the minimum total frequency modulation cost is taken as a control target, the balanced control of energy storage capacity is realized while the frequency modulation requirement of a system is met, the service life of the energy storage is prolonged, and the cost of the distributed energy storage participating in AGC service of the system is reduced.
(2) The electric quantity of each stored energy in the aggregator is controlled by adopting a consistency algorithm, each distributed stored energy only needs to exchange a consistency variable value and a power initial value with adjacent stored energy, each stored energy is locally operated according to the state of the stored energy to update the consistency variable, the communication topology formed by the stored energy with the connectivity of at least 2 can also ensure the operation speed under weak communication contact, and even if part of the distributed stored energy has communication faults, the rest distributed stored energy can still normally operate, so that the communication cost of frequency modulation control is reduced, and certain robustness is achieved.
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FIG. 1 is a schematic flow chart of the method of the present invention.
Fig. 2 is a schematic diagram of the steps of obtaining the energy storage output power at the time k by applying the consistency algorithm.
FIG. 3 is a drawing showing
The function image of (2).
Fig. 4 is a schematic diagram of a distributed energy storage communication topology.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The distributed energy storage aggregator AGC method based on the consistency algorithm disclosed by the invention is shown in figure 1 and mainly comprises two major links: a filtering link and an energy storage output power distribution link.
A first link: the main function of the filtering link is to use the AGC signal P in the modelAGCSeparation into low-frequency components PAGC lowAnd a high frequency component PAGC highAnd respectively transmitting the signals to the traditional unit and the distributed energy storage aggregator to respond.
Wherein the AGC signal PAGCIs calculated from the integral of the area control error ACE. The frequency threshold of filtering is determined by the relative size of the climbing capacity of the traditional unit and the capacity of the energy storage aggregator. If the climbing of the traditional unit is large and the capacity of the energy storage aggregator is small, the threshold value of the filter is set to be high; and if the climbing of the traditional unit is small and the capacity of the energy storage aggregator is large, setting the threshold value of the filter to be low.
The distributed energy storage aggregator macroscopically and collectively schedules a plurality of distributed energy storages to participate in AGC as a whole, and stores an AGC signal P from the external viewAGC highFor the input signal the aggregator controls the output signal, i.e. the sum of the output powers stored in the aggregator. Assuming that the sum of all energy storage frequency modulation power output by the distributed energy storage aggregator is PEA sumThe external control aims to make P as much as possibleEA sumIs close to PAGC high. From the internal view, the control target is to maintain the balance of the energy storage electric quantity, and the control can be dynamically adjusted along with the change of the internal energy storage quantity, thereby realizingAnd controlling and scheduling the plug-and-play type energy storage. And each distributed energy storage in the aggregator is used as an intelligent agent to exchange information with adjacent energy storage, and local operation is performed by using self state information and technical characteristics until all individual consistent variables are approximately the same.
And a second link: in the energy storage output power distribution link, the frequency modulation output of each energy storage is distributed in the aggregator, and the specific steps are shown in fig. 2.
Firstly, the control method of the invention aims to complete the frequency modulation task within the frequency modulation capability range and realize the balance control of each energy storage electric quantity. In order to quantify and realize the control target of the energy storage aggregator, an energy storage frequency modulation cost function is defined and used as a key index for distributing each energy storage frequency modulation output, and the expression is as follows (1):
wherein,
the frequency modulation cost of the nth energy storage at the time k is shown, and the frequency modulation output depth of the nth energy storage at the time k is comprehensively reflected; pn,kThe unit of the output power of the nth stored energy at the k moment is MW, when the output power is larger than zero, the stored energy is in a discharging state, and when the output power is smaller than zero, the stored energy is in a charging state; en,kRepresenting the electric quantity of the nth stored energy at the moment k,
the optimum electric quantity level of the nth stored energy is represented, and the unit is MW & h; a isnAnd bnAnd weights representing the frequency modulation cost brought by the power and electric quantity change of the nth stored energy respectively. For each energy storage individual, anAnd bnCan be set as a constant, wherein, anBy the amount of stored energyThe fixed charge and discharge power is determined, and a is determined when the rated power value is largernThe smaller the value of (c) is set; bnThen the capacity is determined according to the rated capacity of the stored energy, i.e. the larger the stored energy capacity is, the larger bnThe smaller the value of (A), by setting anAnd bnThe parameters can meet the requirements of different energy storages on electric quantity level control in the frequency modulation process;
for the charging efficiency of the nth stored energy,
charging efficiency for the nth stored energy; Δ t represents the time interval between two frequency modulation controls.
The above formula is simplified into a quadratic function form taking the energy storage output power as a single variable, and the formula (2) shows:
wherein,
a quadratic coefficient representing a frequency modulation cost function of the nth stored energy in a charging state;
a quadratic term coefficient representing a frequency modulation cost function of the nth stored energy in a discharge state, wherein the coefficient is determined by the fixed parameter of the stored energy and does not change along with the frequency modulation process;
representing the coefficient of the first order of the frequency modulation cost function when the nth energy storage is in the charging state at the moment k,
the coefficient of the primary term of the frequency modulation cost function when the nth stored energy is in a discharge state at the moment k is represented, and for the same battery stored energy, the coefficient is determined by the battery stored energy parameter and the current charge state and changes along with the frequency modulation process; gamma rayn,kAnd for the nth energy storage, the constant term coefficient of the frequency modulation cost function at the moment k has the same value in the charging and discharging states, and for the same battery energy storage, the coefficient is determined by the battery energy storage parameter and the current charge state and changes along with the frequency modulation process.
The stored energy is constrained by the technical characteristics of the stored energy in the process of participating in frequency modulation, and the stored energy is specifically as follows:
in the formula (3), the reaction mixture is,
and
respectively representing the minimum value and the maximum value of the energy storage running power of the nth battery,
and
respectively representing the minimum value and the maximum value of the nth energy storage climbing rate,
and
respectively representing the maximum value and the minimum value of the nth energy storage capacity.
The inequality constraints are simplified, and the process is as follows:
the formula (4) is simplified as follows:
according to different charging and discharging states of energy storage, the formula (5) can be written as follows:
charging efficiency due to stored energy
And discharge efficiency
Must be less than or equal to zero, and therefore must have:
therefore, formula (c) can be simplified to:
in summary, energy storage technical feature constraints can be summarized as follows:
the value range of the nth energy storage output power is recorded as Pn,k∈ΩE。
Assuming that N energy storage individuals exist in the distributed energy storage aggregator, D is calculatedk cost，NThe total frequency modulation cost of N energy storage individuals at the moment k is defined, and then the control objective function of the control method can be written as follows:
the target function is based on the output power P of each energy storagen,kAs a variant, by limiting the fm cost per stored energy, the amount of energy per stored energy can be maintained around an optimal level, while aiming to minimize the overall cost of the stored energy fm.
And solving the objective function by adopting a consistency algorithm in the distributed energy storage aggregator.
Defining the partial derivative of the frequency modulation cost to the output power as a consistency variable lambda of the algorithm, and then writing the consistency variable expression of the nth energy storage at the k moment as follows:
in the formula, λn,kAnd (4) representing the consistency variable of the nth energy storage at the k moment, and considering the consistency variable as a dimensionless numerical value. As key information of information exchange between adjacent energy storage individuals, the value of each energy storage real-time consistency variable qualitatively reflects the frequency modulation cost brought by each unit of frequency modulation power borne by the energy storage at the moment.
The adjacent energy storage refers to distributed energy storage individuals with communication links.
The step of obtaining the energy storage output power at the time k by applying the consistency algorithm is shown in fig. 2, and specifically includes the following steps:
(1) distributed energy storage initialization
After the frequency modulation control is started, the stored energy is firstly storedThe initial value of the frequency modulation power is transmitted to each energy storage unit in the aggregator. And defining the energy storage individuals in the aggregator directly connected with the filtering link as key energy storage. Energy storage frequency modulation signal PAGC highAfter the key energy storage is transmitted, each energy storage output power initial value is obtained through simple calculation in the energy storage, and the formula (14) shows.
In the formula,
for the initial value of the frequency modulation output of the nth energy storage at the time k, assuming that the number N of the individual energy storage units is known and fixed within a certain time, since the final distribution result is insensitive to the initial value and the value of N is generally large, the number of the energy storage units within the time period is allowed to change slightly.
The initial value signal is rapidly transmitted to all the energy storages in the aggregator in a mode of multi-directional information conduction between adjacent energy storages.
Second, a consistency variable is initialized within each energy store. The nth initial value expression of the energy storage consistency variable is obtained by calculation of the consistency variable definition formula and is shown as the formula (15):
(2) discrimination of adjacent consistency variables
In each frequency modulation control interval, adjacent energy storage is subjected to consistency variable exchange, and respective output power is adjusted until the energy storage consistency variables converge to the same value.
Firstly, the stored energy obtains the consistent variable value of the stored energy adjacent to the stored energy, whether the stored energy is consistent with the consistent variable value of the stored energy is judged, if the stored energy is consistent with the consistent variable value, the stored energy and the adjacent stored energy reach local balance, the step (4) is directly carried out, and if not, the step (3) is directly carried out. In order to prevent the consistency in the actual operation from being achieved in a short time and improve the calculation efficiency, it is considered that the approximately consistent condition shown in the formula (16) is achieved.
In the formula (16), the compound represented by the formula,
the meter energy store x is adjacent to the energy store n,
and
respectively representing the consistency variables of the stored energy n and the stored energy x after the j iteration. And (4) carrying out multiple iterative operations on the kth frequency modulation moment until an approximately consistent condition is met or the calculation time reaches the upper limit (frequency modulation time interval delta t).
(3) Iterative computation of consistency variables
The iterative method of the consistency variables can be divided into five steps, which are respectively shown as formula (17) to formula (21).
And (4) correcting the consistency variable in the last iteration result. In the formula (17), the
Defining the value of a consistency variable of j iteration of the nth stored energy at the kth frequency modulation moment; wherein,
the values of the consistency variable when the value range is not limited are shown. For the j-1 th iteration value
The correction of (2) can be divided into two parts, wherein the first part accumulates the difference value of the consistency variable of the previous j-1 iterations and the adjacent n-th energy storage individual by sigma1Is a correction factor; the second part differentiates the power initial value signal value with the last time output power to reflect the tracking of the frequency modulation signal by sigma2Is a correction factor.
And step two, restraining the consistent variable. OmegaλIndicating the allowable range of the consistency variable of the nth stored energy when
If the value exceeds the range, the corresponding boundary value is taken, otherwise, the value is unchanged. The constraint is to prevent oscillation divergence of the iterative operation under extreme conditions.
And step three, utilizing the consistency variable to reversely deduce the virtual power value. From the equation defined by the uniform variables, λ and
there is a functional relationship as shown in equation (13), which can be expressed as equation (22).
Then, fλ -1Representative function fλDue to the inverse function of fλThe energy storage device is a piecewise function, the piecewise critical points of different energy storage are different, and the inverse function of the piecewise function has various corresponding relations. Under several kinds of conditions fλ -1The function image of (b) is shown in FIG. 3, fλ -1The function images of (1) all take the zero point of the energy storage power as a critical point, and the positive half shaft and the negative half shaft correspond to different function expressions. The lambda value corresponding to the power positive half-axis critical point is called lambda1The lambda value corresponding to the negative half-axis critical point is called lambda2. According to λ1And λ2Relative magnitude relationship of (1), will fλ -1The function image of (2) is divided into three cases, which are indicated by superscripts # 1, #2, and #3, respectively. To ensure lambda and
the one-to-one correspondence relationship between the three cases is defined as follows.
Case # 1: lambda [ alpha ]1>λ2，
Case # 2: lambda [ alpha ]1＝λ2The calculation formula is the same as above.
Case # 3: lambda [ alpha ]1<λ2，
As shown in formula (24), fλ -1*Indicating that f is redefined for a particular intervalλ -1Will be
Defined as a virtual power value. In step (c), fλ -1*Is a corresponding rule, known as
The value is derived to be deficientPseudo power value
Fourthly, the virtual power value obtained in the third step is utilized to correct the power value in the last iteration result, and the energy storage output power value without limited value range is obtained
At σ3Is a correction factor.
Fifthly, constraining the power value to obtain the frequency modulation power distribution result of the jth iteration, namely known omegaERepresents the adjustment capability range of each energy storage unit when
If the value exceeds the range, the corresponding boundary value is taken, otherwise, the value is unchanged.
(4) Time determination of timer
And judging whether the operation time reaches the frequency modulation time interval delta t. And (5) if delta t is reached, otherwise, returning to the step (2).
(5) Output power allocation scheme
And taking the power value obtained by the j-th iteration calculation of the stored energy as output power to participate in system frequency modulation.
(6) Updating energy storage states and parameters
And calculating the current electric quantity of the stored energy according to the actual output power of the stored energy by the formula (1).
And updating the value of each parameter of the energy storage frequency modulation cost function according to the formula (2).
And updating the constraint condition of the energy storage frequency modulation capability according to the formula (11).
The distributed energy storage communication topology is shown in fig. 4, the relationship that each energy storage can exchange information with other energy storage is called as adjacent), the number of individuals adjacent to the energy storage is called as the connectivity of the energy storage, and the connectivity of each energy storage is more than or equal to 2, so as to ensure the normal operation of control, as shown in fig. 4, when the communication line between the energy storage 1 and the energy storage 2 is interrupted. The two can still carry out normal operation control through the information exchange of the energy storage 6 and the energy storage 3 and 4 respectively.
Claims (8)
1. A distributed energy storage aggregator AGC method based on a consistency algorithm is characterized in that an aggregator formed after distributed energy storage concentration is used as a controlled object, a high-frequency component of an aggregator output signal response system AGC signal is used as an external control target, distributed energy storage electricity quantity balance and lowest distributed energy storage frequency modulation cost are used as internal control targets, frequency modulation cost required by distributed energy storage to bear unit frequency modulation power in respective operation states is used as consistency variables of the distributed energy storage, frequency modulation power of the distributed energy storage is initialized in time intervals of adjacent frequency modulation moments, initial values of the consistency variables are determined based on initial values of the frequency modulation power of the distributed energy storage, the numerical values of the consistency variables are updated iteratively when the initial values of the consistency variables are inconsistent, virtual values of the frequency modulation power of the distributed energy storage at the current moment are inverted according to the updated numerical values of the consistency variables, correcting the virtual value of each distributed energy storage frequency modulation power at the current frequency modulation time, and constraining the corrected value of each distributed energy storage frequency modulation power virtual value at the current frequency modulation time within each distributed energy storage frequency modulation capacity range to obtain a frequency modulation power distribution scheme at the current frequency modulation time; wherein,
the expression of the consistency variable of each distributed energy storage is as follows:
wherein λ isn,kFor the n-th distributed energy store, the consistency variable P at the time of the k-modulationn,kThe output power of the nth distributed energy storage at the moment of k frequency modulation,
the coefficient of the quadratic term of the frequency modulation cost function of the nth distributed energy storage in the charging state,
the coefficient of the quadratic term of the frequency modulation cost function of the nth distributed energy storage in the discharging state,
the coefficient of the first order term of the frequency modulation cost function when the nth distributed energy storage is in a charging state at the moment of frequency modulation k,
the coefficient of the first order term of the frequency modulation cost function when the nth distributed energy storage is in a discharge state at the moment of frequency modulation k,
En,k-1the electric quantity of the nth distributed energy storage at the moment of frequency modulation of k-1 is stored,
optimum power level for the nth distributed energy storage, anAnd bnRespectively the weight of the frequency modulation cost brought by the nth distributed energy storage output power and the electric quantity change,
for the charging efficiency of the nth distributed energy storage,
for the discharge efficiency of the nth distributed energy storage, delta t represents the time interval of two frequency modulation controls;
the method for iteratively updating the consistency variable value comprises the following steps:
and correcting the consistency variable of the last iteration:
and then, constraining the corrected consistency variable:
wherein,
the consistency variable value of the j iteration of the nth distributed energy storage at the kth frequency modulation moment is taken,
carrying out the consistency variable value of the j-1 iteration of the nth distributed energy storage at the kth frequency modulation moment, wherein the value is sigma1、σ2Respectively, are the correction coefficients of the image data,
the initial value of the frequency modulation power of the nth distributed energy storage at the k frequency modulation time,
is the high-frequency component of the AGC signal of the system, N is the number of distributed energy storages in the aggregator,
representing the consistent variable value of the jth iteration of the nth distributed energy storage at the kth frequency modulation moment when the value range is not limited, wherein the consistent variable value is omegaλRepresenting the advisable range of the nth distributed energy storage consistency variable, t is the iteration number, and x is the adjacent distributed energy storage of the nth distributed energy storageThe x-th distributed energy storage of (1),
the value of the consistency variable of j-t iteration of the nth distributed energy storage at the kth frequency modulation moment is obtained,
taking the value of the consistency variable of j-t iteration performed at the kth frequency modulation moment for the x distributed energy storage, wherein P is the value of the consistency variablen,k-1And storing the frequency modulation power value of the nth distributed energy storage at the k-1 frequency modulation moment.
2. The distributed energy storage aggregator AGC method based on the consistency algorithm according to claim 1, wherein the system AGC signal high frequency component is obtained by filtering the system AGC signal through a filtering link, and a frequency threshold of the filtering is determined by a relative size of a unit climbing capability and an aggregator capacity.
3. The distributed energy storage aggregator AGC method based on the consistency algorithm as claimed in claim 1, wherein each distributed energy storage frequency modulation cost function is:
wherein,
frequency modulation cost, P, at the time of k frequency modulation for the nth distributed energy storagen,kOutput power at the moment of frequency k modulation for the nth distributed energy store, En,kThe electric quantity of the nth distributed energy storage at the moment of k frequency modulation,
optimum power level for the nth distributed energy storage, anAnd bnAre respectively the nth minuteAnd the weight of the frequency modulation cost brought by the change of the output power and the electric quantity of the distributed energy storage.
4. The distributed energy storage aggregator AGC method based on consistency algorithm as claimed in claim 3, wherein the optimum electric quantity of the nth distributed energy storage
The method is adjusted according to the condition that the distributed energy storage participates in the power grid service, when the distributed energy storage participates in a plurality of power grid services at the same time, the distributed energy storage capacity is distributed to a frequency modulation service part and other service parts according to the proportion of a% and 1-a%,
Snthe capacity of the nth distributed energy storage.
5. The distributed energy storage aggregator AGC method based on the consistency algorithm as claimed in claim 1, wherein the constraint that each distributed energy storage frequency modulation capability satisfies is:
wherein,
and
respectively the minimum value and the maximum value of the nth distributed energy storage operation power,
and
respectively nth distributed energy storage climbing speedThe minimum and maximum values of the rate are,
and
respectively the minimum value and the maximum value, P, of the nth distributed energy storage electric quantityn,k、Pn,k-1Respectively storing the output power of the nth distributed energy storage at the frequency modulation time of k and the frequency modulation time of k-1, En,k-1The electric quantity of the nth distributed energy storage at the moment of frequency modulation of k-1 is stored,
for the charging efficiency of the nth distributed energy storage,
and delta t is the time interval of two frequency modulation controls for the discharge efficiency of the nth distributed energy storage.
6. The AGC method for the distributed energy storage aggregator based on the consistency algorithm as claimed in claim 1, wherein the virtual value of each distributed energy storage frequency modulation power at the current frequency modulation time is inverted according to the updated consistency variable value, and the virtual value is determined according to the power positive half-axis critical point λ1And power negative half-shaft critical point lambda2The numerical value of (a) includes the following two cases:
λ1is greater than or equal to lambda2The method comprises the following steps:
λ1<λ2the method comprises the following steps:
wherein λ is the uniformityThe variables are the variables of the process,
and outputting the virtual value of the output power of the nth distributed energy storage at the k frequency modulation moment.
7. The distributed energy storage aggregator AGC method based on the consistency algorithm as claimed in claim 6,
the expression for correcting the virtual value of each distributed energy storage frequency modulation power at the current frequency modulation time is as follows:
and then, constraining the virtual value of the corrected distributed energy storage frequency modulation power at the current frequency modulation time:
wherein σ3To correct the coefficient, ΩERepresenting the fm capability range of each distributed energy store,
the frequency modulation power obtained by the j-1 iteration performed at the k-1 frequency modulation time for the nth distributed energy storage,
obtaining a correction value of a virtual value of the frequency modulation power for the nth distributed energy storage at the kth frequency modulation time in the jth iteration,
and carrying out j iteration on the nth distributed energy storage at the k-1 th frequency modulation moment to obtain the frequency modulation power.
8. The distributed energy storage aggregator AGC method based on the consistency algorithm as claimed in claim 1, wherein communication between each adjacent distributed energy storage in the aggregator is realized by adopting a communication topology with each distributed energy storage connectivity degree greater than 2, and consistency variable values and initial frequency modulation power values are interacted between the adjacent distributed energy storage.
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