CN113131466B - Control method, device and system for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability - Google Patents

Abstract

The invention discloses a control method, a device and a system for electrochemical energy storage to participate in a low-frequency safe and stable third defense line, wherein the method comprises the steps of obtaining a typical operation mode set and a disturbance fault set; obtaining a frequency response model of a third defense line of electrochemical energy storage participation low-frequency safety and stability; screening out the operation mode causing the minimum power shortage and the corresponding disturbance fault, bringing the operation mode into the frequency response model, and calculating the critical capacity of the electrochemical energy storage in turn; when the critical capacity of the electrochemical energy storage sub-cycle action is smaller than the electrochemical energy storage configuration capacity, optimizing each cycle action amount of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage, and finishing the control of the electrochemical energy storage participating in the third defense line of low-frequency safety and stability. The invention can reduce the action risk of low-frequency load shedding, gradually optimize the configuration capacity and the control effect of the third defense line and improve the capability of the power grid for dealing with extreme faults.

Description

Control method, device and system for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability

technical field

The invention specifically relates to a control method, device and system for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability.

Background technique

At present, electrochemical energy storage has become one of the important technical support means for the large-scale access of new energy and the construction of UHVDC. It has been widely used in power systems and has maintained rapid growth in recent years. The large-capacity power shortage caused by faults in the power grid will cause the system frequency to drop, and may even cause frequency collapse. Low-frequency load shedding is an important part of the third line of defense for frequency safety. It can quickly respond to orderly remove part of the load and prevent further frequency drops. However, low-frequency load shedding itself will still cause a large number of users to lose power and cause greater social impact. Therefore, including electrochemical energy storage, DC and other control resources, and optimizing the traditional frequency correction control strategy is of great significance to improve the ability of the power grid to cope with extreme serious faults.

The electrochemical energy storage system has the characteristics of fast response speed, active/reactive power coordination, two-way control of charge and discharge, and high power conversion efficiency. It can quickly adjust its power output when the grid frequency is offset, and improve the dynamic frequency characteristics of the power system. With the optimization of electrochemical energy storage battery performance and the reduction of cost, it is also more valuable to incorporate electrochemical energy storage into the grid frequency security defense system.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention proposes a control method, device and system for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability, which can reduce the action risk of low-frequency load shedding, and gradually optimize the configuration capacity and control effect of the third line of defense. , to improve the ability of the grid to cope with extreme failures.

In order to realize the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

In the first aspect, the present invention provides a control method for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability, including:

Obtain the typical operating mode set and disturbance fault set;

Obtain the frequency response model of electrochemical energy storage participating in the third line of defense for low-frequency security and stability;

Screen out the operation mode that causes the smallest power shortage and the corresponding disturbance fault, and bring it into the frequency response model to calculate the critical capacity of the electrochemical energy storage in rounds, where the calculation result of the frequency response model is: The electrochemical energy storage output power; the critical capacity of the electrochemical energy storage sub-round action is the maximum value of the electrochemical energy storage output power that satisfies the grid frequency overshoot constraint;

When the critical capacity of the electrochemical energy storage in rounds is less than the configuration capacity of the electrochemical energy storage, the action amount of each round of the electrochemical energy storage is optimized, the control amount of the electrochemical energy storage is obtained, and the participation of the electrochemical energy storage is completed. Low-frequency security and stability control of the third line of defense.

Optionally, the frequency response model is:

When Δf < Δf _m :

in,

a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d .

Optionally, the control amount of the electrochemical energy storage is calculated and obtained by the following steps:

Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is obtained;

The output power increment of the electrochemical energy storage in each round is converted into a ratio of the total installed capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage.

Optionally, the weighted optimization model is:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

表示暂态过程中频率跌至最低值时的峰值频率偏差，

表示高于50Hz的超调暂态频率偏差；Δf_s ^i,j表示稳态频率偏差；Among them, after disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation;

为第h轮切负荷量，

为第k轮电化学储能输出功率增量；N₁和N₂分别为低频减载和电化学储能的低频动作轮数；X表示优化变量，为n个轮次的电化学储能输出功率增量；C _ls , C _es , C _fs , C _fp , and C _fd are load shedding cost coefficient, electrochemical energy storage cost coefficient, steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient, respectively;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment;

The constraints are:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot.

Optionally, the calculation formula of the control amount of the electrochemical energy storage is:

Among them, P _s,k is the output power increment of the k-th round of electrochemical energy storage, and P _s,N is the total installed capacity of electrochemical energy storage.

In the second aspect, the present invention provides a control device for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability, including:

a first acquisition unit, used to acquire a set of typical operating modes and a set of disturbance faults;

The second acquisition unit is used to acquire the frequency response model of the electrochemical energy storage participating in the third line of defense of low-frequency safety and stability;

The calculation unit is used to filter out the operation mode and the corresponding disturbance fault that cause the smallest power shortage, and bring it into the frequency response model to calculate the critical capacity of the electrochemical energy storage in rounds, wherein the frequency response model The calculation result of is the output power of the electrochemical energy storage; the critical capacity of the electrochemical energy storage sub-round action is the maximum value of the output power of the electrochemical energy storage that satisfies the grid frequency overshoot constraint;

The control unit is configured to optimize the action amount of each round of electrochemical energy storage when the critical capacity of the electrochemical energy storage sub-round action is less than the configuration capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage, and complete Electrochemical energy storage is involved in the control of the third line of defense for low-frequency security and stability.

Optionally, the frequency response model is:

When Δf < Δf _m :

in,

a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d .

Optionally, the control amount of the electrochemical energy storage is calculated and obtained by the following steps:

Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is obtained;

The output power increment of the electrochemical energy storage in each round is converted into a ratio of the total installed capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage.

Optionally, the weighted optimization model is:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

表示暂态过程中频率跌至最低值时的峰值频率偏差，

表示高于50Hz的超调暂态频率偏差；Δf_s ^i,j表示稳态频率偏差；After disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation;

为第h轮切负荷量，

为第k轮电化学储能输出功率增量；N₁和N₂分别为低频减载和电化学储能的低频动作轮数；X表示优化变量，为n个轮次的电化学储能输出功率增量。C _ls , C _es , C _fs , C _fp , and C _fd are load shedding cost coefficient, electrochemical energy storage cost coefficient, steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient, respectively;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment.

The constraints are:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot.

Optionally, the calculation formula of the control amount of the electrochemical energy storage is:

Among them, P _s,k is the output power increment of the k-th round of electrochemical energy storage, and P _s,N is the total installed capacity of electrochemical energy storage.

In a third aspect, the present invention provides a control system for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability, including a storage medium and a processor;

the storage medium is used for storing instructions;

The processor is adapted to operate in accordance with the instructions to perform the steps of the method according to any of the first aspects.

Compared with the prior art, the beneficial effects of the present invention:

The invention can make the electrochemical energy storage cooperate with the existing low-frequency load shedding scheme, and respond to typical and random faults in the power grid by performing actions in rounds, and achieve a better frequency recovery effect with a smaller control cost.

Secondly, the invention can make full use of the advantages of flexible and fast adjustment of electrochemical energy storage, gradually optimize the configuration capacity and control effect of the third line of defense, improve the ability of the power grid to cope with extreme failures, and also help to improve the utilization benefit of electrochemical energy storage .

Description of drawings

In order to make the content of the present invention easier to be understood clearly, the present invention will be described in further detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic flowchart of a control method for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the protection scope of the present invention.

The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1

The embodiment of the present invention provides a control method for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability, comprising the following steps:

Obtain a set of typical operating modes and a set of disturbance faults that cause large power shortages;

Obtain the frequency response model of electrochemical energy storage participating in the third line of defense for low-frequency security and stability;

Screen out the operation mode that causes the smallest power shortage and the corresponding disturbance fault, and bring it into the frequency response model to calculate the critical capacity of the electrochemical energy storage in rounds, wherein the calculation result of the frequency response model is the electrical The output power of the chemical energy storage; the critical capacity of the electrochemical energy storage divided into rounds is the maximum value of the output power of the electrochemical energy storage that satisfies the grid frequency overshoot constraint;

When the critical capacity of the electrochemical energy storage in rounds is less than the configuration capacity of the electrochemical energy storage, the action amount of each round of the electrochemical energy storage is optimized, the control amount of the electrochemical energy storage is obtained, and the participation of the electrochemical energy storage is completed. Low-frequency security and stability control of the third line of defense.

In the specific implementation process, the method in the embodiment of the present invention, as shown in FIG. 1 , specifically includes:

(1) Carry out the data preparation for scheme setting, and obtain the operation mode, topology, historical operation data, historical fault conditions, low-frequency load shedding and electrochemical energy storage configuration of the power grid from the operation department of the power grid. Among them, the operation mode and topology structure of the power grid are used for the equivalence of the power grid, and the weighted average method, parameter identification method and other methods are used to equivalence the generator, load, electrochemical energy storage and other models in the power system, and the single-machine belt concentration is obtained. Load model; historical operation data is used to formulate the typical operation mode set C, historical faults mainly consider the third-level standard faults of safety and stability, and are used to formulate the disturbance fault set F that causes high power shortage; the configuration of low-frequency load shedding and electrochemical energy storage The situation is used to tune the program parameters of electrochemical energy storage participating in the third line of defense of low-frequency safety.

(2) Based on historical statistical information, select the typical operating mode set C and the disturbance fault set F that cause large power shortages.

Due to the complexity and variability of the operation modes of the power grid, it is impossible to calculate all the operation modes one by one. In order to reduce the workload, several typical operation modes are selected, including summer large, summer small, winter large, winter small and so on. Through the analysis of the power grid data over the years, the cumulative running time of various operation modes of the power grid, the types and times of faults, and the probability distribution are obtained, and the representative typical operation mode set C is selected; Stability analysis, the large disturbance fault set F that may cause large power shortage is obtained in the third-level standard fault of safety and stability. The low-frequency correction control scheme of electrochemical energy storage needs to adapt to various operating modes and faults in C and F.

(3) Establish a frequency response model for electrochemical energy storage to participate in the third line of defense for low-frequency security and stability. The frequency response model takes into account the influence of electrochemical energy storage control characteristics, specifically:

The frequency response model is:

When Δf < Δf _m :

in,

a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d .

Through the frequency response expression, the transient frequency index after the occurrence of power shortage disturbance and the low-frequency action of electrochemical energy storage can be calculated, including steady-state frequency, peak frequency, etc. Among them, the peak frequency deviation can be obtained by derivation, and the steady-state frequency deviation can be expressed as:

(4) Set the number n of action rounds of electrochemical energy storage, the frequency threshold f _e,k of starting each round, and the action delay t _e,k of each round. The setting of parameters needs to be based on the frequency response characteristics of the power grid and coordinate with the low-frequency load shedding measures. The specific setting principles are as follows:

The action delay of each round needs to take into account both the stability control system error prevention and the frequency control effect, and is generally set to 200-300ms. Too many action rounds will affect the control effect due to the action delay. Too few action rounds will easily cause over-control. Generally, it is set to 3 to 5 rounds. Considering the operating range of the normal frequency of the power grid and the operating requirements of primary frequency regulation, the action threshold of the first round of electrochemical energy storage should not be higher than 49.5Hz. During the chemical energy storage operation rounds, the frequency difference between the electrochemical energy storage operation rounds can be determined by 0.1 ~ 0.2 Hz, and the frequency difference between the final electrochemical energy storage round and the first round of low-frequency load shedding can be determined by 0.1 ~ 0.2 Hz considered.

(5) Carry out the analysis and calculation of the critical capacity of electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability;

The meaning of critical capacity is: when the electrochemical energy storage capacity that can be used for the third line of defense in the power grid is higher than this value, it must be performed in rounds, so as to avoid low-frequency action of electrochemical energy storage to cause high-frequency cutting or new energy. Chain accidents such as unit disconnection. Combined with the typical operation mode set C and the disturbance fault set F, screen out the operation mode and the corresponding disturbance fault that cause the smallest power shortage, and bring it into the frequency response model in step (3) to calculate the power grid that satisfies the frequency overshoot constraint of the grid. Chemical energy storage output power. The maximum value of the output power of the electrochemical energy storage is taken as the critical capacity for its participation in the third line of defense in rounds.

(6) Under the condition that the configuration capacity of electrochemical energy storage is higher than the critical capacity of the sub-round action, optimize the action amount of each round of electrochemical energy storage to obtain the control amount of electrochemical energy storage (that is, obtain the electrochemical energy storage capacity). Can low frequency action plan)

In a specific implementation of the embodiment of the present invention, the control amount of the electrochemical energy storage is calculated and obtained by the following steps:

Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is calculated; the output power increment of each round of electrochemical energy storage is converted into The ratio of the total installed capacity of electrochemical energy storage to obtain the control amount of electrochemical energy storage.

The specific implementation process is as follows: formulate a comprehensive index based on the frequency recovery effect and control cost, establish a weighted optimization model considering various fault scenarios and operating modes, and combine the electrochemical energy storage power control capability and the grid transient frequency safety constraints to set the calculation power Low-frequency action control of chemical energy storage.

The comprehensive index to characterize the frequency recovery effect and control cost is:

表示暂态过程中频率跌至最低值时的峰值频率偏差，

表示高于50Hz的超调暂态频率偏差；Δf_s ^i,j表示稳态频率偏差；C_ls、C_es、C_fs、C_fp、C_fd分别为切负荷代价系数、电化学储能代价系数、稳态频率指标系数、峰值频率指标系数和超调频率指标系数；

为第h轮切负荷量，

为第k轮电化学储能输出功率增量；N₁和N₂分别为低频减载和电化学储能的低频动作轮数；X表示优化变量，为n个轮次的电化学储能输出功率增量。Among them, after disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation; C _ls , C _es , C _fs , C _fp , and C _fd are the load shedding cost coefficient and the electrochemical energy storage cost coefficient, respectively , steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment.

The selection principles of the above coefficients and the unified method of their dimensions are as follows: the cost of load shedding control is higher than that of electrochemical energy storage control, and the weight of peak frequency and overshoot frequency is higher than that of steady-state frequency; It is expressed by the relative value of the electrochemical energy storage low-frequency action amount or load shedding amount in the rated electrochemical energy storage/load power in each operation mode, and the dimension of the control cost under different operation modes is unified.

The objective function is weighted and summed according to the probability of each operation mode and failure in the typical operation mode set C and the disturbance fault set F causing large-capacity power shortage, and the weighted optimization model is obtained as:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

Regarding the constraints related to the power control capability of electrochemical energy storage and the safety and stability of the grid transient frequency, the constraints are formulated as follows:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot.

Under this constraint, taking the minimum weighted optimization model as the optimization objective, the optimal electrochemical energy storage action amount is obtained, and the increment of each round of electrochemical energy storage is converted to account for the total installed capacity of electrochemical energy storage P _{s , the ratio of N} I _k , to obtain the optimal low-frequency action control quantity of electrochemical energy storage with comprehensive indicators, namely:

(7) Check the line power flow in the system after the low-frequency correction control action. If the power distribution scheme of the electrochemical energy storage is unreasonably configured, it will cause the power flow after the control to exceed the limit and other problems, resulting in line overload and cascading failures. Perform transient simulation analysis on the low-frequency correction control scheme and the fault set F, and check the power flow of the line. If it is unreasonable, re-adjust the action settings of each round of electrochemical energy storage until the power flow distribution is reasonable.

Example 2

An embodiment of the present invention provides a control device for electrochemical energy storage to participate in the third line of defense for low-frequency safety and stability, including:

a first acquisition unit, used for acquiring a set of typical operation modes and a set of disturbance faults causing large power shortage;

The second acquisition unit is used to acquire the frequency response model of the electrochemical energy storage participating in the third line of defense of low-frequency safety and stability;

The calculation unit is used to screen out the operation mode and the corresponding disturbance fault that cause the smallest power shortage, and bring it into the frequency response model to calculate the critical capacity of the electrochemical energy storage in rounds;

The control unit is configured to optimize the action amount of each round of electrochemical energy storage when the critical capacity of the electrochemical energy storage sub-round action is less than the configuration capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage, and complete Electrochemical energy storage is involved in the control of the third line of defense for low-frequency security and stability.

In a specific implementation of the embodiment of the present invention, the frequency response model is:

When Δf < Δf _m :

in,

a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d .

The control amount of the electrochemical energy storage is calculated and obtained through the following steps:

Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is obtained;

The output power increment of the electrochemical energy storage in each round is converted into a ratio of the total installed capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage.

Wherein, the weighted optimization model is:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

表示暂态过程中频率跌至最低值时的峰值频率偏差，

表示高于50Hz的超调暂态频率偏差；Δf_s ^i,j表示稳态频率偏差；C_ls、C_es、C_fs、C_fp、C_fd分别为切负荷代价系数、电化学储能代价系数、稳态频率指标系数、峰值频率指标系数和超调频率指标系数；

为第h轮切负荷量，

为第k轮电化学储能输出功率增量；N₁和N₂分别为低频减载和电化学储能的低频动作轮数；X表示优化变量，为n个轮次的电化学储能输出功率增量。Among them, after disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation; C _ls , C _es , C _fs , C _fp , and C _fd are the load shedding cost coefficient and the electrochemical energy storage cost coefficient, respectively , steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment.

The constraints are:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot.

The calculation formula of the control amount of the electrochemical energy storage is:

Among them, P _s,k is the output power increment of the k-th round of electrochemical energy storage, and P _s,N is the total installed capacity of electrochemical energy storage.

The rest are the same as in Example 1.

Example 3

The embodiment of the present invention provides a control system for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability, including a storage medium and a processor;

the storage medium is used for storing instructions;

The processor is configured to operate in accordance with the instructions to perform the steps of the method according to any of Embodiment 1.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a 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, etc.) 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 present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative rather than restrictive. Under the inspiration of the present invention, without departing from the scope of protection of the present invention and the claims, many forms can be made, which all belong to the protection of the present invention.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

1. a control method of electrochemical energy storage participating in the third line of defense of low-frequency safety and stability, is characterized in that, comprises: Obtain the typical operating mode set and disturbance fault set; Obtain the frequency response model of electrochemical energy storage participating in the third line of defense for low-frequency security and stability; Screen out the operation mode and the corresponding disturbance fault that cause the smallest power shortage, and bring it into the frequency response model, and then obtain the critical capacity of the electrochemical energy storage sub-round action, wherein the calculation result of the frequency response model is the electrical The output power of the chemical energy storage; the critical capacity of the electrochemical energy storage divided into rounds is the maximum value of the output power of the electrochemical energy storage that satisfies the grid frequency overshoot constraint; When the critical capacity of the electrochemical energy storage in rounds is less than the configuration capacity of the electrochemical energy storage, the action amount of each round of the electrochemical energy storage is optimized, the control amount of the electrochemical energy storage is obtained, and the participation of the electrochemical energy storage is completed. Low-frequency safety and stability control of the third line of defense; The frequency response model is: When Δf< _Δfm :

in, a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d . 2. a kind of electrochemical energy storage according to claim 1 participates in the control method of the third line of defense of low frequency safety and stability, it is characterized in that, the control amount of described electrochemical energy storage is calculated and obtained by following steps: Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is obtained; The output power increment of the electrochemical energy storage in each round is converted into a ratio of the total installed capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage. 3. a kind of electrochemical energy storage according to claim 2 participates in the control method of the third line of defense of low frequency safety and stability, it is characterized in that, described weighted optimization model is:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

Among them, after disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation; C _ls , C _es , C _fs , C _fp , and C _fd are load shedding cost coefficient, electrochemical energy storage cost coefficient, steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient, respectively;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment; The constraints are:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot. 4. a kind of electrochemical energy storage according to claim 2 participates in the control method of the third line of defense of low frequency safety and stability, it is characterized in that: the calculation formula of the control amount of described electrochemical energy storage is:

Among them, P _s,k is the output power increment of the k-th round of electrochemical energy storage, and P _s,N is the total installed capacity of electrochemical energy storage. 5. A control device for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability, characterized in that it comprises: a first acquisition unit, used to acquire a set of typical operating modes and a set of disturbance faults; The second acquisition unit is used to acquire the frequency response model of the electrochemical energy storage participating in the third line of defense of low-frequency safety and stability; the calculation unit is used to filter out the operation mode that causes the smallest power shortage and the corresponding disturbance fault, and bring it into the frequency response model, and then obtain the critical capacity of the electrochemical energy storage sub-round action, wherein, the calculation result of the frequency response model is the output power of the electrochemical energy storage; the critical capacity of the electrochemical energy storage sub-round action is The maximum value of the output power of the electrochemical energy storage that satisfies the grid frequency overshoot constraint; The control unit is configured to optimize the action amount of each round of electrochemical energy storage when the critical capacity of the electrochemical energy storage sub-round action is less than the configuration capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage, and complete Electrochemical energy storage participates in the control of the third line of defense for low-frequency safety and stability; The frequency response model is: When Δf< _Δfm :

in, a= _ξωn

K=K _L +K _G

When Δf>Δf _m :

in,

In the formula, Δf(t) is the time domain expression of the frequency deviation value; P _e represents the active power deficit of the system; H _G is the inertia time constant of the power system, defined as the generator rotor energy _{E MWS} = The ratio of Jω _r ² /2 to the rated capacity S _N of the motor; P _s is the output active power of the electrochemical energy storage; Δf is the frequency deviation value, Δf _m is the corresponding value when the governor reaches the maximum adjustable power P _{m,max KL} is the static frequency regulation effect coefficient of the load; _KG is the power frequency characteristic coefficient of the generator, _TG is the time constant of the governor; if the time for the frequency to reach the starting threshold is t _e , after the delay t After _d , the electrochemical energy storage adjusts the output power, that is, the action time is t _z =t _e +t _d . 6. a kind of electrochemical energy storage according to claim 5 participates in the control device of the third line of defense of low frequency safety and stability, it is characterized in that, the control amount of described electrochemical energy storage is calculated and obtained by following steps: Taking the preset weighted optimization model minimum as the optimization goal, combined with the preset constraints, the output power increment of each round of electrochemical energy storage is obtained; The output power increment of the electrochemical energy storage in each round is converted into a ratio of the total installed capacity of the electrochemical energy storage to obtain the control amount of the electrochemical energy storage. 7. a kind of electrochemical energy storage according to claim 6 participates in the control device of the third line of defense of low frequency safety and stability, is characterized in that, described weighted optimization model is:

Among them, F(X) ^i,j is the comprehensive index of disturbance fault j in operation mode i; λ _i is the probability of operation in mode i, μ _j is the probability of disturbance fault j; N _c is the number of typical operation modes , N _d is the number of fault scenarios;

Among them, after disturbance fault j occurs in operation mode i,

Represents the peak frequency deviation when the frequency drops to the lowest value during the transient process,

represents the overshoot transient frequency deviation higher than 50Hz; Δf _s ^i,j represents the steady-state frequency deviation; C _ls , C _es , C _fs , C _fp , and C _fd are load shedding cost coefficient, electrochemical energy storage cost coefficient, steady-state frequency index coefficient, peak frequency index coefficient and overshoot frequency index coefficient, respectively;

is the load cut amount of the h-th round,

is the output power increment of the k-th round of electrochemical energy storage; N ₁ and N ₂ are the number of low-frequency action rounds of low-frequency load shedding and electrochemical energy storage, respectively; X represents the optimization variable, which is the output of n rounds of electrochemical energy storage power increment; The constraints are:

Among them, P _s,k is the output power increment of the k-th electrochemical energy storage system, P _s,max is the maximum output power value of the electrochemical energy storage system; f _s is the steady-state frequency, f _s,min and f _s,max are the minimum and maximum constraints of the steady-state frequency, respectively; f _d represents the transient frequency overshoot, and f _{d, max} is the maximum limit of the transient frequency overshoot. 8. a kind of electrochemical energy storage according to claim 6 participates in the control device of the third line of defense of low frequency safety and stability, it is characterized in that, the calculation formula of the control amount of described electrochemical energy storage is:

Among them, P _s,k is the output power increment of the k-th round of electrochemical energy storage, and P _s,N is the total installed capacity of electrochemical energy storage. 9. A control system for electrochemical energy storage to participate in the third line of defense of low-frequency safety and stability, characterized in that it comprises a storage medium and a processor; the storage medium is used to store instructions; The processor is adapted to operate in accordance with the instructions to perform the steps of the method according to any of claims 1-4.

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