阅读说明：本技术 一种百兆瓦级储能参与调峰及频率响应辅助服务的联合调度方法 (Joint scheduling method for hundred megawatt energy storage participating peak shaving and frequency response auxiliary service ) 是由 刘娆 周校聿 鲍福增 常燕南 巴宇 王海霞 于 2021-08-04 设计创作，主要内容包括：本发明提供一种百兆瓦级储能参与调峰及频率响应辅助服务的联合调度方法,属于大规模电化学储能参与电力系统调度领域。首先,探究常规火电机组与百兆瓦级储能共同参与双重辅助服务的联合调度原则；其次,根据调度原则建常规火电机组与百兆瓦级储能共同参与双重辅助服务的联合调度模型；最后,采用两阶段迭代方式对联合调度模型进行解算。本发实现了百兆瓦级储能与常规火电机组的协同以及百兆瓦级储能自身参与调峰、频率响应的出力空间分配,所提出的联合调度方法可以减少系统弃风损失,提高系统的频率安全水平,降低系统运行的总成本,为大规模储能参与电网侧调度的方式提供参考。(The invention provides a joint scheduling method for participation of hundred megawatt energy storage in peak shaving and frequency response auxiliary service, and belongs to the field of participation of large-scale electrochemical energy storage in scheduling of a power system. Firstly, exploring a joint scheduling principle that a conventional thermal power generating unit and hundreds of megawatt energy storage jointly participate in dual auxiliary services; secondly, a joint scheduling model of the conventional thermal power generating unit and the hundred megawatt energy storage jointly participating in double auxiliary services is established according to a scheduling principle; and finally, resolving the joint scheduling model by adopting a two-stage iteration mode. The method realizes the cooperation of the hundred-megawatt energy storage and the conventional thermal power generating unit and the output space distribution of the hundred-megawatt energy storage participating in peak shaving and frequency response, and the proposed combined scheduling method can reduce the loss of the abandoned wind of the system, improve the frequency safety level of the system, reduce the total cost of the system operation, and provide reference for the way of the large-scale energy storage participating in the side scheduling of the power grid.)

1. A joint scheduling method for participation of hundred megawatt energy storage in peak shaving and frequency response auxiliary service is characterized by comprising the following steps:

step 1: determining a scheduling principle that the hundred megawatt-level energy storage and a conventional thermal power generating unit jointly participate in dual auxiliary services;

the energy storage participates in the joint scheduling of the dual auxiliary services and the unit, and the coordination of the energy storage and the unit and the dual auxiliary services of the energy storage comprises the following steps:

in the coordination of energy storage and the unit: the frequency response layer preferentially ensures the frequency safety; on the premise of exerting the response capability of the unit, the energy storage supplements a frequency response demand gap; the peak regulation layer is used for optimizing the operation economy as a target by combining the peak regulation requirement;

in the coordination of two auxiliary services of the energy storage itself: firstly, ensuring the frequency safety of the system, and then participating in system peak regulation; when the energy storage participates in the two types of auxiliary services, the coordination problem of time scales with different differences must be considered when the same model is jointly optimized; converting the instantaneous output dynamic change time sequence of the energy storage needing to participate in the frequency response into frequency response spare capacity which needs to be reserved for ensuring the constraint of the formula (11) in the step 2 within every 15min, and optimizing the frequency response of the energy storage and the peak shaving input amount under the same time scale in a spare capacity constraint mode, wherein the spare capacity constraint is shown as the formula (9) in the step 2;

step 2: establishing a joint optimization mathematical model according to a scheduling principle that the hundred megawatt-level energy storage and a conventional thermal power generating unit jointly participate in dual auxiliary services, and optimizing the model once every 24h on a system scheduling level to obtain power and capacity results of the unit combination, the wind power output and the energy storage participating peak regulation and fast frequency response dual auxiliary services on the next day at one time; the optimization target is that the total cost is the lowest, and an objective function is set as follows:

wherein:

wherein F is the total cost;the starting cost of the unit i is calculated;the shutdown cost of the unit i; a is_i、b_i、c_iSecondary, primary and constant term coefficients of the unit operation cost function; c^B1Fast frequency response electricity price for energy storage; c^B3Adjusting peak electricity price for energy storage; c^WFor unit loss when the wind abandon exceeds the limit；The unit deep peak shaving first-gear electricity price is obtained;adjusting the peak second electricity price for the unit depth;the running power of the unit i in the time period t is set;the upper power limit of the unit i is set; p_t ^B1Storing fast frequency response standby power for the energy in a time period t; p_t ^B3Peak shaving power of the stored energy in a time period t; p_t ^QWAbandoning the power exceeding the limit for the time t;the average load rate of the unit i in the time period t is shown;starting and stopping a unit i at a time t; n is a radical of_tOptimizing the total number of time periods for scheduling; n is a radical of_GThe number of the units;

and step 3: step 3 is the constraint conditions of the formula (1) in the step 2, including unit constraint, energy storage constraint and system constraint;

the unit constraint is similar to the traditional unit combination constraint and comprises a self power upper and lower limit constraint, a climbing rate constraint, a rotation standby constraint and a minimum start-stop time constraint;

the energy storage constraint is shown in formulas (3) to (9); in each time interval of the stored energy, the adjustment direction of each auxiliary service can only be one, and the auxiliary service is released when not being charged, namely, the constraint of the charging and discharging state is expressed as:

in the formula (I), the compound is shown in the specification,energy storage peak-shaving charging and discharging marks for a time period t;charging and discharging marks for storing energy basic charging and discharging power for a time period t;

the stacking sum of the charging and discharging power of each specified energy storage auxiliary service in each time interval must not exceed the maximum output power of self charging and discharging, namely the constraint of the sum of the power is as follows:

wherein:

in the formula (I), the compound is shown in the specification,representing the maximum charging and discharging power of the stored energy;representing whether the time period t energy storage participates in the rapid frequency response; mu is the percentage of the charge-discharge power of the energy storage basis to the upper limit and the lower limit of the energy storage basis; p_t ^B3,cha、P_t ^B3,disCharging and discharging power for energy storage peak regulation; p_t ^BRRepresenting the energy storage basic charge and discharge power for recovering the SOC; p_t ^BR,cha、P_t ^BR,disRepresents P_t ^BRThe charging and discharging power of;

the electric quantity in each energy storage time interval must not exceed the upper and lower limits of the energy storage time interval, and a coupling relation exists between adjacent time intervals, which is expressed as:

in the formula (I), the compound is shown in the specification,representing the upper limit and the lower limit of the energy storage capacity;representing the amount of energy stored for a time period t; eta_c、η_dRepresenting the charging and discharging efficiency of the stored energy; Δ T15 min represents the duration of each period;

in order to ensure that the energy storage can execute scheduling tasks according to a plan every day, the difference between the electric quantity of the energy storage at the end of the whole day and the electric quantity of the energy storage at the initial time period is not too large, namely, the electric quantity constraint at the beginning and the end is as follows:

in the formula (I), the compound is shown in the specification,representing an initial value of the energy storage capacity;representing the remaining value of the energy storage capacity after the whole day; gamma is an allowable deviation;

the energy storage frequency response standby power needs to meet the minimum standby power requirement value P_t ^B1,refAs shown in equation (9), calculated by the system frequency safety constraint;

P_t ^B1≥P_t ^B1,ref (9)

the system constraints are shown as formulas (10) and (11), and comprise power balance constraints and frequency safety constraints; the power balance constraint requires that the unit output, the stored energy output and the wind power output meet the load power together, and is expressed as follows:

in the formula, P_t ^WRepresenting wind power grid-connected power; p_t ^LRepresenting the load power;

the frequency safety constraint requires that the lowest value of the system frequency must not be lower than the safety lower limit:

in the formula (f)_t ^nadirRepresents the lowest frequency of the time period t; f. of^sRepresents a system-specified lower frequency safety limit;

the energy storage is only subjected to virtual droop control to adjust the output, even if the to-be-optimized variable of the energy storage frequency response output only has a droop control coefficient; neglecting load damping when analytically calculating the lowest value of the frequency, and when suffering maximum power disturbance in the time period tThen, the lowest frequency value can be calculated according to the system disturbance, the output of the unit and the output of the stored energy, as shown in the formula (12-15);

in the formula (I), the compound is shown in the specification,the unit inertial response coefficient;the capacity of the unit i;whether energy is stored for the time period t to participate in frequency response or not;the energy storage droop control coefficient is obtained;the linear climbing rate of the unit i is obtained;linear ramp rate for energy storage; t is_i ^G、K_i ^GThe response time constant and the difference adjustment coefficient of the unit i are obtained; t is^BIs the energy storage response time constant;is the time when the time period t reaches the lowest frequency; f. of⁰Is the initial frequency; f. of^BIs a reference frequency;

and 4, step 4: when the frequency is reduced to the lowest f_t ^nadirThe system frequency difference is maximum, and the primary frequency modulation output power of all the unitsAs shown in formula (16), and hasIf the system frequency minimum value f is calculated according to the primary frequency modulation output power of all the units_t ^nadirIf the frequency safety constraint of equation (11) is not satisfied, the virtual droop coefficient K of the stored energy needs to be increased_t ^BUntil the lowest frequency of the system satisfies f_t ^nadir≥f^sThen, the frequency response reserve power requirement P required by equation (9) in step 3 is calculated_t ^B1,refAs shown in formula (17);

and 5: step 5, carrying out optimization calculation on the formula (1) in the step 2, wherein the optimization result needs to satisfy the constraint conditions shown in the formulas (3) to (11); the solution adopts two-stage iteration, the joint optimization is divided into two-stage problems, the two problems are respectively solved and iterated repeatedly, and then the overall optimization is realized, specifically:

the main problem is that the stored energy participates in peak shaving, the linear unit combination problem which meets system power balance together with the unit is solved, only the constraints of the formulas (3) to (10) are considered when the formula (1) is optimized, the process takes the stored frequency response standby power into account, and the stored frequency response standby power requires P_t ^B1,refThe value needs to be determined according to the optimization result of the value in the subproblem; the sub-problem is the frequency safety constraint problem under the optimization result of the main problem, and the requirement that the formula (11) corrects P according to the formula (17)_t ^B1,refIn the process, the frequency lowest value of the system is calculated according to the frequency response capability of the starting unit under the result of the main problem, if the frequency lowest value is not calculated, the system is startedIf the frequency safety constraint is met in non-all time periods, energy storage is called, and the droop control coefficient of the energy storage is increased according to the specified step length;

and repeating iteration of the two problems until all time intervals meet the frequency safety constraint, stopping optimization, realizing the solution of the combined optimization scheduling model, and obtaining the starting and stopping states of the unit, the output of the unit, the wind power on-line power, the power of the energy storage participating in peak shaving and the reserve power of the energy storage participating in frequency response in each time interval of the next day at one time.

Technical Field

The invention belongs to the field of large-scale electrochemical energy storage participation electric power system scheduling, and particularly relates to a combined scheduling method for hundred megawatt-level energy storage participation peak shaving and frequency response auxiliary service.

Background

The installed capacity of the newly added renewable energy in 2020 world exceeds 260GW, the increase amount is close to 1.5 times of 2019, and due to the requirement of the double-carbon target, the capacity of a photovoltaic generator is 7500 ten thousand watts, and the renewable energy is gradually becoming the dominant power supply in China in at least every year in the next 10 years. The large amount of renewable energy sources is connected to the grid, so that the occupation ratio of conventional units with frequency response capability in the power system is reduced, however, the 'double high' characteristic of the novel power system puts higher requirements on the system frequency, and the demand for quick frequency response of the power grid is increased. In addition, the peak regulation requirement of the power system is increased by the peak regulation characteristic of renewable energy sources such as wind power, the minimum technical output of the unit is limited, and the peak regulation pressure of the system is obviously increased.

The electrochemical energy storage has high response speed and is convenient for accurate control, and is a high-quality peak and frequency modulation resource. At present, electrochemical energy storage is often utilized to stabilize output fluctuation of wind, light and other renewable energy sources so as to reduce system peak-valley difference, or an output control strategy of energy storage primary frequency modulation or secondary frequency modulation is formulated based on unilateral frequency modulation requirements of a power grid. The existing research is mainly aimed at binding the stored energy and new energy or placing the stored energy on the load side to adjust the output according to the self charge state, and the reason is that the conventional electrochemical energy storage scale is small, and the output only has the auxiliary effect on peak regulation and frequency regulation of a power grid. Nowadays, large-scale electrochemical energy storage is built on the power grid side all over the world, and national policies propose to develop novel energy storage, so that the energy storage can play a role in regulation and guarantee on a larger scale to support the construction of novel power systems.

The large-scale energy storage can be used for directly carrying out peak clipping and valley filling on the power grid side according to the power grid requirement, can respond to frequency modulation signals more quickly, can provide high-quality auxiliary service when being applied to the power grid side, guarantees the safety of the power grid, improves the electric energy quality and delays or avoids the capacity expansion and transformation of an original power transmission system. The analysis of the capability of a large-scale energy storage system for improving the consumption of renewable energy in northwest regions indicates that the large-scale energy storage can effectively improve the consumption of new energy and quickly recover the frequency reduction caused by direct-current blocking faults, and hundred megawatt-level energy storage is recommended to be deployed in a northwest power grid. However, most of the existing researches on large-scale energy storage at the system side involve the large-scale energy storage in automatic power generation control of a power grid by adopting different control strategies, so that the problems of insufficient secondary frequency modulation capacity and poor frequency modulation performance of a power system are solved. Although a united model for energy storage and energy-frequency modulation market participation is proposed in the research on the united dispatching mode of the energy storage power station participating in the energy-frequency modulation market, the model aims at the profit mode of the energy storage, and does not consider the benefits of a power grid. At present, there is a few researches on considering large-scale energy storage to participate in dual auxiliary services and the coordination of energy storage and units in the aspect of power system scheduling. Therefore, it is supposed to utilize the power and capacity advantages of large-scale energy storage (especially hundreds of megawatt energy storage) to participate in peak shaving and frequency response dual auxiliary services.

The invention provides a joint scheduling method for participation of hundred megawatt energy storage in peak shaving and frequency response auxiliary service. The method is used for exploring a joint scheduling principle that a conventional thermal power generating unit and the hundred megawatt energy storage jointly participate in dual auxiliary services and providing a joint scheduling model aiming at the joint scheduling problem that the hundred megawatt electrochemical energy storage participates in the dual auxiliary services of peak shaving and frequency response of a power system at the side of a power grid. The method realizes the cooperation of the hundred-megawatt energy storage and the conventional thermal power generating unit and the output space distribution of the hundred-megawatt energy storage participating in peak shaving and frequency response, and provides reference for the mode that large-scale energy storage participates in the side dispatching of the power grid.

Disclosure of Invention

The policy in China supports the development of large-scale energy storage to improve the flexibility of a power system and support the construction of a novel power system, however, the existing research mostly participates in a certain auxiliary service aiming at energy storage, neglects the large-scale energy storage and has both power and capacity, and can participate in double auxiliary services of peak regulation and rapid frequency response at the same time. Aiming at the problems, the invention provides a joint scheduling method for a conventional thermal power generating unit (hereinafter referred to as a unit) and a hundred-megawatt energy storage unit (hereinafter referred to as an energy storage unit) to jointly participate in dual auxiliary services, the method realizes the cooperation of the hundred-megawatt energy storage unit and the conventional thermal power generating unit and the output space distribution of the hundred-megawatt energy storage unit participating in peak shaving and frequency response, and provides reference for the mode that large-scale energy storage participates in the side scheduling of a power grid.

In order to achieve the purpose, the invention adopts the technical scheme that:

a joint scheduling method for participation of hundred megawatt energy storage in peak shaving and frequency response auxiliary service comprises the following steps:

step 1: the essence of the hundred-megawatt energy storage participating in peak shaving and frequency response dual auxiliary service scheduling of the power system is that the optimal allocation of each resource participating in peak shaving and frequency response reserved output space is completed, and the unit combination containing the hundred-megawatt energy storage output plan considering the frequency response requirements of the system consisting of the conventional thermal power unit and the hundred-megawatt energy storage is adopted. Based on a basic idea of considering system operation economy on the premise of ensuring system frequency safety, a scheduling principle that the hundred megawatt-level energy storage unit and a conventional thermal power generating unit jointly participate in double auxiliary services is determined.

The energy storage participates in the joint scheduling of the dual auxiliary services and the unit, and the coordination between the energy storage and the unit and between the dual auxiliary services of the energy storage itself are included, as shown in fig. 1.

In the coordination of energy storage and the unit: and on the frequency response level, the frequency safety is preferentially ensured. Because the primary frequency modulation provides basic auxiliary service for the generator set in a gratuitous way, the frequency response requirement gap is supplemented by the stored energy on the premise of fully playing the response capability of the generator set. And (3) in the aspect of peak shaving, considering the overall economy of the system, integrating multiple factors such as the deep peak shaving cost of the unit, the calling cost of energy storage, the cost of wind abandoning punishment and the like, and combining the peak shaving demand to optimize the operation economy as a target.

In the coordination of two auxiliary services of the energy storage itself: and the system frequency is preferably ensured to be safe, and then the system peak regulation is participated. Because the unit combination is the optimization result of time scale every 15min in the day ahead, and the frequency response needs to consider the dynamic process from several seconds to tens of seconds after the disturbance occurs, the coordination problem of time scale with great difference must be considered when the energy storage participates in the joint optimization of the two types of auxiliary services in the same model. And (3) converting the instantaneous output dynamic change time sequence of the energy storage needing to participate in the frequency response into the frequency response spare capacity which needs to be reserved for ensuring the constraint of the formula (11) in the step 2 within every 15min, and optimizing the frequency response of the energy storage and the peak shaving input amount under the same time scale in a spare capacity constraint mode, wherein the spare capacity constraint is shown as the formula (9) in the step 2.

Step 2: a joint optimization mathematical model is established according to a scheduling principle that the hundred megawatt-level energy storage and a conventional thermal power generating unit jointly participate in dual auxiliary services, the model is optimized once every 24h on the system scheduling level, and power and capacity results (the optimization interval is 15min, namely 96 optimization time periods each day) of the unit combination, the wind power output and the energy storage participating in peak shaving and the fast frequency response dual auxiliary services on the next day are obtained once. The optimization target is that the total cost is minimum and the target function is set as

Wherein

Wherein F is the total cost;the starting cost of the unit i is calculated;for stopping unit iMachine cost; a is_i、b_i、c_iSecondary, primary and constant term coefficients of the unit operation cost function; c^B1Fast frequency response electricity price for energy storage; c^B3Adjusting peak electricity price for energy storage; c^WThe unit loss is the unit loss when the abandoned wind exceeds the limit;the unit deep peak shaving first-gear electricity price is obtained;adjusting the peak second gear electricity price for the unit depth;the running power of the unit i in the time period t is set;the upper power limit of the unit i is set; p_t ^B1Storing fast frequency response standby power for the energy in a time period t; p_t ^B3Peak shaving power of the stored energy in a time period t; p_t ^QWAbandoning the power exceeding the limit amount for the time t;the average load rate of the unit i in the time period t is shown;starting and stopping states (1 starting and 0 stopping) of a unit i in a time period t; n is a radical of_tOptimizing the total number of time periods for scheduling; n is a radical of_GThe number of the units.

And step 3: and step 3 is the constraint condition of the formula (1) in the step 2, which comprises unit constraint, energy storage constraint and system constraint, and the network trend constraint is ignored because the problem of collaborative optimization of energy storage, the unit and dual auxiliary services of the energy storage is mainly discussed.

The unit constraint is similar to the traditional unit combination constraint and comprises self power upper and lower limit constraint, climbing rate constraint, rotation standby constraint and minimum start-stop time constraint.

The energy storage constraint is shown in formulas (3) to (9). The energy storage is in each time interval, the adjustment direction of each auxiliary service can only be one, and the auxiliary service is released when not being charged, namely, the constraint of the charging and discharging state is expressed as

In the formula (I), the compound is shown in the specification,energy storage peak-shaving charging and discharging marks for a time period t;and storing charge and discharge marks (both variable 0-1) of the basic charge and discharge power for the time period t.

The stacking sum of the charging and discharging power of each specified energy storage auxiliary service in each time interval does not exceed the maximum output power of self charging and discharging, namely the power sum is constrained to be

Wherein

In the formula (I), the compound is shown in the specification,representing the maximum charging and discharging power of the stored energy;indicating whether the time period t energy storage participates in the fast frequency response (1 is yes, 0 is no); mu is the percentage of the charge-discharge power of the energy storage basis to the upper limit and the lower limit of the energy storage basis; p_t ^B3,cha、P_t ^B3,disCharging and discharging power for energy storage peak regulation; p_t ^BRIndicating stored energyBasic charge-discharge power for recovering the SOC; p_t ^BR,cha、P_t ^BR,disRepresents P_t ^BRThe charging and discharging power of.

The electric quantity in each energy storage time interval does not exceed the upper limit and the lower limit of the energy storage time interval, and a coupling relation exists between adjacent time intervals, and is specifically expressed as

In the formula (I), the compound is shown in the specification,representing the upper limit and the lower limit of the energy storage capacity;representing the amount of energy stored for a time period t; eta_c、η_dRepresenting the charging and discharging efficiency of the stored energy; Δ T15 min represents the duration of each period.

In order to ensure that the energy storage can execute the scheduling task according to the plan every day, the electric quantity of the energy storage at the end of the whole day and the initial time interval should not be too different, namely, the initial electric quantity and the final electric quantity are restricted to be

In the formula (I), the compound is shown in the specification,representing an initial value of the energy storage capacity;representing the remaining value of the energy storage capacity after the whole day; γ is the allowable deviation.

Energy storage frequency response standby power needs to meet its minimum standbyUsing power demand value P_t ^B1,refAs shown in equation (9), the value is calculated according to the system frequency safety constraint, which is detailed in step 4.

P_t ^B1≥P_t ^B1,ref (9)

The system constraints comprise power balance constraints and frequency safety constraints as shown in formulas (10) and (11). The power balance constraint requires that the unit output, the stored energy output and the wind power output meet the load power together, and is expressed as

In the formula, P_t ^WRepresenting wind power grid-connected power; p_t ^LRepresenting the load power.

The frequency safety constraint requires that the lowest value of the system frequency is not lower than the safety lower limit

In the formula (f)_t ^nadirRepresents the lowest frequency of the time period t; f. of^sIndicating a system-specified lower frequency safety limit.

In order to avoid the complexity of the combined optimization calculation, the energy storage is only subjected to virtual droop control to adjust the output, even if the variable to be optimized of the energy storage frequency response output is only the droop control coefficient. Neglecting load damping when analytically calculating the lowest value of the frequency, and when suffering maximum power disturbance in the time period tAnd then, the lowest frequency value can be calculated according to the system disturbance, the unit output and the energy storage output, as shown in the formula (12-15).

In the formula (I), the compound is shown in the specification,the unit inertial response coefficient;the capacity of the unit i;whether energy is stored for the time period t to participate in frequency response or not (1 is yes, 0 is no);the energy storage droop control coefficient is obtained;the linear climbing rate of the unit i is obtained;linear ramp rate for energy storage; t is_i ^G、The response time constant and the difference adjustment coefficient of the unit i are obtained; t is^BIs the energy storage response time constant;time period t reaches the lowest frequency; f. of⁰Is the initial frequency; f. of^BIs a baseQuasi-frequency.

And 4, step 4: when the frequency is reduced to the lowest f_t ^nadirThe system frequency difference is maximum, and the primary frequency modulation output power of all the unitsIs shown as formula (16) and hasIf the system frequency minimum value f is calculated according to the primary frequency modulation output power of all the units_t ^nadirIf the frequency safety constraint of equation (11) is not satisfied, the virtual droop coefficient of the stored energy needs to be increasedUntil the lowest frequency of the system satisfies f_t ^nadir≥f^sThen, the frequency response reserve power requirement P required by equation (9) in step 3 is calculated_t ^B1,refAs shown in formula (17).

And 5: and 5, performing optimization calculation on the formula (1) in the step 2, wherein the optimization result needs to meet the constraint conditions shown in the formulas (3) to (11). The solution adopts two-stage iteration, the joint optimization is divided into two-stage problems, and the two problems are respectively solved and iterated repeatedly to realize the overall optimization, as shown in fig. 2.

The main problem is that the stored energy participates in peak shaving, and the stored energy and the unit jointly meet the linear unit combination problem of system power balance (only the constraints of the expressions (3) to (10) are considered when the expression (1) is optimized), the process takes the frequency response standby power of the stored energy into account, and the frequency response standby power of the stored energy requires P_t ^B1,refThe value needs to be determined according to the optimization result of the value in the subproblem; seed of Japanese apricotProblem is the frequency safety constraint problem under the optimization result of the main problem (P is corrected according to formula (17) to satisfy formula (11))_t ^B1,ref) And in the process, the frequency lowest value of the system is calculated according to the frequency response capability of the starting unit under the main problem result, if the frequency safety constraint is met in all the time intervals, the stored energy is called, and the droop control coefficient of the stored energy is increased according to the specified step length.

And repeating iteration of the two problems until all time periods meet the frequency safety constraint, stopping optimization, realizing the solution of the combined optimization scheduling model, and obtaining the starting and stopping states of the unit, the output of the unit, the wind power on-line power, the power of the energy storage participating in peak shaving and the reserve power of the energy storage participating in frequency response in each time period of the next day at one time.

The invention has the beneficial effects that: the invention provides a method for the cooperation of the hundred-megawatt energy storage with the conventional thermal power generating unit and the output space distribution of the hundred-megawatt energy storage participating in peak shaving and frequency response. The method considers that the hundred megawatt-level energy storage participates in the dual auxiliary service, can reduce the wind curtailment loss of the system, reduce the deep peak regulation pressure of the unit, improve the frequency safety level of the system, reduce the total cost of the system operation, also is beneficial to the balance of the total charging and discharging amount of the energy storage, assists in recovering the SOC of the energy storage, and ensures that the energy storage can better execute the scheduling instruction according to the auxiliary service requirement of the system.

Drawings

FIG. 1 is a joint scheduling principle;

FIG. 2 is a model solution diagram;

FIG. 3 shows daily load, wind power forecast, and maximum disturbance data for each time interval.

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention with reference to the specific embodiments of the present invention and the accompanying drawings.

A joint scheduling method for participation of hundred megawatt energy storage in peak shaving and frequency response auxiliary service specifically comprises the following steps:

step 1: the essence of the hundred-megawatt energy storage participating in peak shaving and frequency response dual auxiliary service scheduling of the power system is that the optimal allocation of each resource participating in peak shaving and frequency response reserved output space is completed, and the unit combination containing the hundred-megawatt energy storage output plan considering the frequency response requirements of the system consisting of the conventional thermal power unit and the hundred-megawatt energy storage is adopted. Based on a basic idea of considering system operation economy on the premise of ensuring system frequency safety, a scheduling principle that the hundred megawatt-level energy storage unit and a conventional thermal power generating unit jointly participate in double auxiliary services is determined.

The energy storage participates in the joint scheduling of the dual auxiliary services and the unit, and the coordination between the energy storage and the unit and between the dual auxiliary services of the energy storage itself are included, as shown in fig. 1.

In the coordination of energy storage and the unit: and on the frequency response level, the frequency safety is preferentially ensured. Because the primary frequency modulation provides basic auxiliary service for the generator set in a gratuitous way, the frequency response requirement gap is supplemented by the stored energy on the premise of fully playing the response capability of the generator set. And (3) in the aspect of peak shaving, considering the overall economy of the system, integrating multiple factors such as the deep peak shaving cost of the unit, the calling cost of energy storage, the cost of wind abandoning punishment and the like, and combining the peak shaving demand to optimize the operation economy as a target.

In the coordination of two auxiliary services of the energy storage itself: and the system frequency is preferably ensured to be safe, and then the system peak regulation is participated. Because the unit combination is the optimization result of time scale every 15min in the day ahead, and the frequency response needs to consider the dynamic process from several seconds to tens of seconds after the disturbance occurs, the coordination problem of time scale with great difference must be considered when the energy storage participates in the joint optimization of the two types of auxiliary services in the same model. And (3) converting the instantaneous output dynamic change time sequence of the energy storage needing to participate in the frequency response into the frequency response spare capacity which needs to be reserved for ensuring the constraint of the formula (11) in the step 2 within every 15min, and optimizing the frequency response of the energy storage and the peak shaving input amount under the same time scale in a spare capacity constraint mode, wherein the spare capacity constraint is shown as the formula (9) in the step 2.

Step 2: a joint optimization mathematical model is established according to a scheduling principle that the hundred megawatt-level energy storage and a conventional thermal power generating unit jointly participate in dual auxiliary services, the model is optimized once every 24h on the system scheduling level, and power and capacity results (the optimization interval is 15min, namely 96 optimization time periods each day) of the unit combination, the wind power output and the energy storage participating in peak shaving and the fast frequency response dual auxiliary services on the next day are obtained once. The optimization target is that the total cost is minimum and the target function is set as

Wherein

Wherein F is the total cost;the starting cost of the unit i is calculated;the shutdown cost of the unit i; a is_i、b_i、c_iSecondary, primary and constant term coefficients of the unit operation cost function; c^B1Fast frequency response electricity price for energy storage; c^B3Adjusting peak electricity price for energy storage; c^WThe unit loss is the unit loss when the abandoned wind exceeds the limit;the unit deep peak shaving first-gear electricity price is obtained;adjusting the peak second gear electricity price for the unit depth;the running power of the unit i in the time period t is set;the upper power limit of the unit i is set; p_t ^B1Storing fast frequency response standby power for the energy in a time period t; p_t ^B3Peak shaving power of the stored energy in a time period t; p_t ^QWAbandoning the power exceeding the limit amount for the time t;the average load rate of the unit i in the time period t is shown;starting and stopping states (1 starting and 0 stopping) of a unit i in a time period t; n is a radical of_tOptimizing the total number of time periods for scheduling; n is a radical of_GThe number of the units.

The abandoned wind loss cost and the auxiliary service cost of the unit and the stored energy are set according to the auxiliary service operation rule of the northeast electric power market, as shown in table 1. When the set wind abandon rate is more than 2%, the loss cost is paid.

TABLE 1 abandon wind loss and auxiliary service cost of unit and energy storage

And step 3: the optimized constraint conditions comprise unit constraint, energy storage constraint and system constraint, and because the problem of collaborative optimization of energy storage and unit and dual auxiliary services of the energy storage is mainly discussed, the network trend constraint is ignored.

The system adopts a ten-machine system, and the unit constraint is similar to the traditional unit combination constraint and comprises self power upper and lower limit constraint, climbing rate constraint, rotation standby constraint and minimum start-stop time constraint.

The energy storage constraints are shown in equations (3) - (9). The energy storage is in each time interval, the adjustment direction of each auxiliary service can only be one, and the auxiliary service is released when not being charged, namely, the constraint of the charging and discharging state is expressed as

In the formula (I), the compound is shown in the specification,energy storage peak-shaving charging and discharging marks for a time period t;and storing charge and discharge marks (both variable 0-1) of the basic charge and discharge power for the time period t.

The stacking sum of the charging and discharging power of each specified energy storage auxiliary service in each time interval does not exceed the maximum output power of self charging and discharging, namely the power sum is constrained to be

Wherein

In the formula (I), the compound is shown in the specification,representing the maximum charging and discharging power of the stored energy;indicating whether the time period t energy storage participates in the fast frequency response (1 is yes, 0 is no); mu is the percentage of the charge-discharge power of the energy storage basis to the upper limit and the lower limit of the energy storage basis; p_t ^B3,cha、P_t ^B3,disCharging and discharging power for energy storage peak regulation; p_t ^BRRepresenting the energy storage basic charge and discharge power for recovering the SOC; p_t ^BR,cha、P_t ^BR,disRepresents P_t ^BRThe charging and discharging power of.

The electric quantity in each energy storage time interval does not exceed the upper limit and the lower limit of the energy storage time interval, and a coupling relation exists between adjacent time intervals, and is specifically expressed as

In the formula (I), the compound is shown in the specification,representing the upper limit and the lower limit of the energy storage capacity;representing the amount of energy stored for a time period t; eta_c、η_dRepresenting the charging and discharging efficiency of the stored energy; Δ T15 min represents the duration of each period.

In order to ensure that the energy storage can execute the scheduling task according to the plan every day, the electric quantity of the energy storage at the end of the whole day and the initial time interval should not be too different, namely, the initial electric quantity and the final electric quantity are restricted to be

In the formula (I), the compound is shown in the specification,representing an initial value of the energy storage capacity;representing the remaining value of the energy storage capacity after the whole day; γ is the allowable deviation. The energy storage parameter is S^B＝800MWh，T^B＝0.1s， η_c＝η_d＝1，μ＝10％，γ＝8％。

The energy storage frequency response standby power needs to meet the minimum standby power requirement value P_t ^B1,refAs shown in equation (9), the value is calculated according to the system frequency safety constraint, which is detailed in step 4.

P_t ^B1≥P_t ^B1,ref (9)

The system constraints include power balance constraints and frequency safety constraints as shown in equations (10) and (11). The power balance constraint requires that the output, the stored energy output and the wind power output of the unit meet the load power together, and is expressed as

In the formula, P_t ^WRepresenting wind power grid-connected power; p_t ^LRepresenting the load power.

The frequency safety constraint requires that the lowest value of the system frequency is not lower than the safety lower limit

In the formula (f)_t ^nadirRepresents the lowest frequency of the time period t; f. of^sThe lower limit of the frequency safety specified by the system is shown, and the frequency safety limit f of the system is set in the embodiment^sIs 49.5 Hz.

In order to avoid the complexity of the combined optimization calculation, the energy storage is only subjected to virtual droop control to adjust the output, even if the variable to be optimized of the energy storage frequency response output is only the droop control coefficient. Neglecting load damping when analytically calculating the lowest value of the frequency, and when suffering maximum power disturbance in the time period tAnd then, the lowest frequency value can be calculated according to the system disturbance, the unit output and the energy storage output, as shown in the formula (12-15).

In the formula (I), the compound is shown in the specification,the unit inertial response coefficient;the capacity of the unit i;whether energy is stored for the time period t to participate in frequency response or not (1 is yes, 0 is no);the energy storage droop control coefficient is obtained;the linear climbing rate of the unit i is obtained;linear ramp rate for energy storage; t is_i ^G、The response time constant and the difference adjustment coefficient of the unit i are obtained; t is^BIs the energy storage response time constant;time period t reaches the lowest frequency; f. of⁰Is the initial frequency; f. of^BIs the reference frequency.

In this example, the frequency response related parameters of the ten units are set according to parameters of a certain power grid unit, as shown in table 2.

TABLE 2 frequency response related parameters of unit

And 4, step 4: when the frequency is reduced to the lowest f_t ^nadirThe system frequency difference is maximum, and the primary frequency modulation output power of all the unitsIs shown as formula (16) and hasIf the system frequency minimum value f is calculated according to the primary frequency modulation output power of all the units_t ^nadirIf the frequency safety constraint of equation (11) is not satisfied, the virtual droop coefficient of the stored energy needs to be increasedUntil the lowest frequency of the system satisfies f_t ^nadir≥f^sThen, the frequency response reserve power requirement P required by equation (9) in step 3 is calculated_t ^B1,refAs shown in formula (17).

And 5: and 5, performing optimization calculation on the formula (1) in the step 2, wherein the optimization result needs to meet the constraint conditions shown in the formulas (3) to (11). The solution adopts two-stage iteration, the joint optimization is divided into two-stage problems, and the two problems are respectively solved and iterated repeatedly to realize the overall optimization, as shown in fig. 2.

The main problem is that the stored energy participates in peak shaving, and the stored energy and the unit jointly meet the linear unit combination problem of system power balance (only the constraints of the expressions (3) to (10) are considered when the expression (1) is optimized), the process takes the frequency response standby power of the stored energy into account, and the frequency response standby power of the stored energy requires P_t ^B1,refThe value needs to be determined according to the optimization result of the value in the subproblem; the sub-problem is the frequency safety constraint problem under the optimization result of the main problem (P is corrected according to the formula (17) to satisfy the formula (11))_t ^B1,ref) And in the process, the frequency lowest value of the system is calculated according to the frequency response capability of the starting unit under the main problem result, if the frequency safety constraint is met in all the time intervals, the stored energy is called, and the droop control coefficient of the stored energy is increased according to the specified step length.

And repeating iteration of the two problems until all time periods meet the frequency safety constraint, stopping optimization, realizing the solution of the combined optimization scheduling model, and obtaining the starting and stopping states of the unit, the output of the unit, the wind power on-line power, the power of the energy storage participating in peak shaving and the reserve power of the energy storage participating in frequency response in each time period of the next day at one time.

The daily load of the system, the predicted power of the wind power and the maximum disturbance power in each period in this example are shown in fig. 3.

According to the calculation result, when the energy storage participates in the peak regulation and frequency response dual auxiliary services, the system wind abandon is greatly reduced compared with the system without the energy storage, the maximum wind abandon is reduced by 14%, and the wind abandon amount in all periods is lower than 2% of the total wind power output power of the same period. The lowest value of the system frequency is all higher than the safety lower limit, so that the frequency safety is ensured. The total operating cost of the system is 596717, which is lower than the total operating cost 707081 without stored energy. And in the time interval that the unit needs to carry out deep peak shaving, the average load rate of the unit is reduced to some extent. In addition, the frequency response discharge adjustment of the stored energy and the charging peak-shaving direction of the stored energy are opposite under most conditions, so that the situation that the SOC of the stored energy is higher after the stored energy participates in the dual auxiliary service can be relieved, the charging and discharging amount of the stored energy in the whole day is balanced, the recovery of the SOC of the stored energy is facilitated, and the auxiliary service task can be completed under the worse situation by the stored energy.

Therefore, the method for joint scheduling of the hundred-megawatt energy storage participating in peak shaving and frequency response dual auxiliary services can reduce the loss of system wind curtailment, reduce the deep peak shaving pressure of a unit, improve the frequency safety level of the system, reduce the total cost of system operation, contribute to the balance of the total charging and discharging amount of the energy storage, assist in recovering the SOC of the energy storage, and ensure that the energy storage can better execute scheduling instructions according to the auxiliary service requirements of the system.

The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that those skilled in the art can make several variations and modifications without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.