Energy storage demand assessment method based on provincial power grid power balance

Abstract

The present invention relates to the field of power distribution technology, and specifically to a method for evaluating energy storage demand based on the power and electricity balance of a provincial power grid, comprising establishing a power balance constraint equation for a provincial power grid; analyzing the output coefficients of new energy units under different operating modes based on the historical operating data of the power grid; analyzing the output coefficients of conventional thermal power units and hydropower units based on the installed capacity of the units under a given operating mode of the power grid; analyzing the power and electricity surplus of the system during off-peak load periods and the electricity shortage during peak load periods; solving the energy storage capacity based on the constraints that the energy storage configuration capacity must meet, and proposing energy storage demand indicators and energy storage development margin indicators based on the actual energy storage capacity of the power grid, for evaluating the current energy storage development status of the power grid and the future energy storage development situation. The method configures the energy storage capacity of the power grid and evaluates whether the energy storage configuration capacity meets the power grid's requirements for energy storage participation in power and electricity balance analysis.

Description

Technical Field

[0001] The present invention belongs to the field of power distribution technology, and in particular relates to an energy storage demand assessment method based on provincial power grid power balance. Background Art

[0002] Clean energy substitution is the only way to achieve carbon emission targets. While the proportion of clean energy is gradually increasing, the large-scale, unstable power supply poses challenges to the stable operation of the power grid, and in some areas, curtailment of wind and solar power leads to resource waste. Energy storage has become a key component of renewable energy substitution, complementing renewable energy development to enhance the flexibility and security of the energy system.

[0003] Electrochemical energy storage technology has become one of the key technologies used by many countries today to advance their carbon neutrality goals. In terms of grid transmission and distribution and ancillary services, the main functions of energy storage technology are grid peak shaving, loading, starting and alleviating transmission congestion, and delaying upgrades of transmission and distribution networks. On the user side, energy storage is mainly used for industrial and commercial peak shaving and valley filling, demand-side response, and energy cost management. The value of energy storage depends on the system, and the energy storage requirements vary in different scenarios on the power supply side, the grid side, and the user side. Energy storage on the power supply side is used to smooth fluctuations in renewable energy power generation output, participate in frequency and peak regulation ancillary services, solve new energy consumption problems, and enhance the winter peak regulation capacity of cogeneration units.

[0004] However, there is currently no public method to evaluate whether the configured energy storage capacity meets the grid's requirements for energy storage to participate in power and electricity balance analysis. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for evaluating energy storage demand based on the power and electricity balance of a provincial power grid, configure the energy storage capacity of the power grid, and evaluate whether the energy storage configuration capacity meets the power grid's demand for energy storage participation in power and electricity balance analysis.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for evaluating energy storage demand based on provincial power grid power balance, comprising the following steps:

[0007] Step 1: Establish the power balance constraint equation of the provincial power grid;

[0008] Step 2: Based on the historical operation data of the power grid, analyze the output coefficients of the new energy units under different operation modes; under a given operation mode of the power grid, based on the installed capacity of the units, analyze and obtain the output coefficients of conventional thermal power units and hydropower units;

[0009] Step 3: Based on the provincial power grid power balance constraint equation, analyze the system power and electricity surplus during off-peak load periods and the electricity shortage during peak load periods;

[0010] Step 4: Calculate the energy storage capacity based on the constraints that the energy storage configuration capacity must meet, and propose energy storage demand indicators and energy storage development margin indicators based on the actual energy storage capacity of the power grid to evaluate the current and future energy storage development status of the power grid.

[0011] In the preferred solution, in step 1, the specific operations are as follows:

[0012] The power balance constraint of the provincial power grid is shown in the following formula.

[0013] (1)

[0014] Where, Indicates the output power of thermal power unit; Indicates the output power of the hydropower unit; Indicates the output power of new energy; Indicates the UHVDC input power; Indicates the power of the inter-provincial AC tie line. A positive value indicates input power, and a negative value indicates output power, i.e., power transmitted to other provinces. Indicates the energy storage output power. When the value is positive, it indicates that the energy storage is in a discharging state, and when it is negative, it indicates that the energy storage is in a charging state. Indicates the system load power;

[0015] The output power of renewable energy is related to the output coefficient of renewable energy and the installed capacity of renewable energy, as shown in the following formula:

[0016] (2)

[0017] Where, Indicates the output coefficient of wind turbines in the province, Indicates the installed capacity of wind turbines in the province, Indicates the photovoltaic output coefficient of the province, Represents the province’s photovoltaic installed capacity.

[0018] In the preferred solution, in step 2, the output coefficients of the new energy units include wind power and photovoltaic output coefficients respectively, and the calculation steps are as follows:

[0019] S201. Arrange the wind power and photovoltaic output data during the analysis period from large to small to obtain the array shown in the following formula:

[0020] (3)

[0021] (4)

[0022] Where, It represents the array of wind power historical operation data arranged from large to small during the analysis period. Represents an array Middle i data, the number of historical data selected is ; Represents an array of photovoltaic historical operating data arranged from large to small during the analysis period. Represents an array Middle j data, the number of historical data selected is ;

[0023] S102. Considering the 95% confidence interval, select the 95% data in the two arrays and calculate the wind power output coefficient respectively. and photovoltaic output coefficient , the expression is as follows:

[0024] (5)

[0025] (6)

[0026] Where, Represents an array of wind power output data arranged from large to small In the middle, 95% of the data; Represents an array of photovoltaic output data arranged from large to small In the middle, 95% of the data; It represents the installed capacity of wind turbines in the province; Represents the province’s photovoltaic installed capacity.

[0027] In a preferred solution, in step 2, for conventional thermal power units and hydropower units, under a given grid operation mode, based on the installed capacity of the units and taking spinning standby into account, there are corresponding output coefficient values, which are expressed as follows:

[0028] (7)

[0029] (8)

[0030] Where, Indicates the output power of thermal power unit, Indicates the output coefficient of the thermal power unit under a given operating mode, Indicates the installed capacity of thermal power plants; Indicates the output power of the hydropower unit. Indicates the output coefficient of the hydropower unit under a given operating mode, Indicates the installed capacity of the hydropower generator.

[0031] In the preferred solution, in step 3, under a given operating mode and without considering energy storage peak regulation, the power and power surplus of the system during the off-peak load period are analyzed, and the expression is as follows:

[0032] (9)

[0033] (10)

[0034] Where, Indicates the system surplus power during the off-peak load period, Indicates the output of thermal power units during the off-peak load period. Indicates the output of hydropower units during the off-peak load period. Indicates the output of new energy during the off-peak load period. Indicates the UHVDC input power during off-peak load period, Indicates the AC interconnection line power during the off-peak load period, Indicates the load during the off-peak load period; Indicates the power surplus during off-peak load period. Indicates the start time of the low load period. represents the end time of the off-peak load period, and formula (10) represents the chargeable amount of energy storage when there is a power surplus during the off-peak load period.

[0035] In the preferred solution, in step 3, the expression for the power shortage during the peak load period is as follows:

[0036] (11)

[0037] (12)

[0038] Where, Indicates power shortage during peak load period. Indicates the output of thermal power units during peak load periods. Indicates the output of hydropower units during peak load period. Indicates the output of new energy during peak load period. Indicates the UHVDC power during peak load period, Indicates the AC tie line power during peak load period, Indicates the load during peak load period; Indicates the power shortage during peak load period. Indicates the start time of the peak load period, Indicates the end time of the peak load period.

[0039] In the preferred solution, in step 4, the constraint expression that the energy storage configuration capacity needs to meet is as follows:

[0040] (13)

[0041] (14)

[0042] (15)

[0043] Formula (13) indicates that the energy storage capacity needs to be able to meet the power shortage demand of the system during peak load periods, and formula (14) indicates that the energy storage charging capacity needs to meet the power shortage demand during peak load periods; Indicates the energy storage capacity, Indicates the maximum charge and discharge power of energy storage, Indicates the charging and discharging time of the maximum power of the energy storage; Formula (15) indicates that the chargeable amount during the off-peak load period must be greater than or equal to the power shortage during the peak load period. Indicates the energy storage charging and discharging efficiency.

[0044] In the preferred solution, in step 4, the energy storage demand index and energy storage development margin indicators The expression is as follows:

[0045] (16)

[0046] (17)

[0047] Where, Indicates the actual energy storage capacity of the power grid, represents the energy storage demand index, represents the energy storage development margin index, It indicates that the new capacity of energy storage is planned every year according to demand. This value can be known through the power balance analysis in future years.

[0048] The present invention provides a method for evaluating energy storage demand based on provincial power grid power balance, which has the following beneficial effects:

[0049] 1. Step 1 of the present invention considers the output power factors of all power supplies required by the provincial power grid to meet its own load. Typically, when analyzing the power balance of a provincial power grid, given boundary conditions are used. However, due to the diversity of power system operating modes and the complexity of unit output, the power value of the AC tie line is a key determining factor when establishing the provincial power balance constraint, and its transmission power also has a certain degree of randomness.

[0050] 2. In step 2 of the present invention, the output of the new energy units under a given operating mode and time period of the power grid is analyzed based on historical data. The output coefficient under the given operating mode is obtained based on operating experience and taking into account the 95% confidence interval. This can more accurately obtain the output coefficient of the new energy units, and thus more accurately obtain the output power of the new energy. According to conventional thermal power units and hydropower units, the output coefficients of conventional thermal power units and hydropower units are considered to be large and small, and their output power is analyzed more accurately. This step can more accurately analyze and obtain the output power of new energy and conventional units, because the existing analysis method uses a new energy output coefficient of 0.05 under high load mode, and the conventional power supply usually considers an output coefficient of 1.0, which cannot accurately reflect the actual operation of the power system.

[0051] 3. In step 3 of the present invention, the charging and discharging characteristics of the energy storage are taken into consideration. To ensure that the energy storage can still participate in peak load regulation and absorb surplus electricity during the off-peak load period the next day, it is necessary to ensure that the energy charged during the off-peak load period of the previous day can be released during the peak load period of the same day. This fully utilizes the supporting role of energy storage charging and discharging for the power system, ensuring not only power balance but also energy balance, effectively avoiding situations where the power balance is insufficient or the energy balance is sufficient but the power is insufficient.

[0052] 4. In step 4 of the present invention, it is evaluated whether the existing energy storage configuration capacity of the power grid can meet the power balance of the future power grid as the load of the provincial power grid increases by utilizing the charging and discharging characteristics of energy storage, thereby providing a theoretical basis for planners to timely adjust the scale of power supply, energy storage and new energy development. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will be further described below with reference to the accompanying drawings and examples:

[0054] Figure 1 is the total factor curve of the system in the embodiment

[0055] Figure 2 This is the power generation load curve required by the system after deducting the power output of hydropower, new energy, AC / DC interconnection lines, and gas-fired power generation in the embodiment. DETAILED DESCRIPTION

[0056] A method for assessing energy storage demand based on the power and electricity balance of a provincial power grid analyzes the output of new energy units under a given grid operating mode and time period based on historical data. Based on operating experience and a 95% confidence interval, the output coefficient for a given operating mode is calculated. Under a given operating mode and without energy storage for peak shaving, the system's power and electricity surplus during off-peak load periods is analyzed. The charging and discharging characteristics of energy storage are then considered. To ensure that energy storage can still participate in peak shaving and absorb surplus electricity during off-peak load periods the next day, it is necessary to ensure that the energy charged during the previous off-peak load period can be discharged during the current day's peak load period. Finally, the energy storage capacity is calculated based on the constraints that the energy storage configuration capacity must meet. Combined with the actual energy storage capacity of the grid, energy storage demand indicators and energy storage development margin indicators are proposed to assess the current and future development of energy storage in the grid.

[0057] The specific steps include:

[0058] Step 1: Establish the power balance constraint equation of the provincial power grid.

[0059] The power balance constraint of the provincial power grid is shown in the following formula.

[0060] (1)

[0061] Where, Indicates the output power of thermal power unit; Indicates the output power of the hydropower unit; Indicates the output power of new energy; Indicates the UHVDC input power; Indicates the power of the inter-provincial AC tie line. A positive value indicates input power, and a negative value indicates output power, i.e., power transmitted to other provinces. Indicates the energy storage output power. When the value is positive, it indicates that the energy storage is in a discharging state, and when it is negative, it indicates that the energy storage is in a charging state. Indicates the system load power.

[0062] The output power of renewable energy is related to the output coefficient of renewable energy and the installed capacity of renewable energy, as shown in the following formula:

[0063] (2)

[0064] Where, Indicates the output coefficient of wind turbines in the province, Indicates the installed capacity of wind turbines in the province, Indicates the photovoltaic output coefficient of the province, Represents the province’s photovoltaic installed capacity.

[0065] Step 2: Based on the historical operation data of the power grid, analyze the output coefficients of new energy units under different operation modes; under a given operation mode of the power grid, based on the installed capacity of the units, analyze and obtain the output coefficients of conventional thermal power units and hydropower units.

[0066] The output coefficients of new energy units include wind power and photovoltaic output coefficients. The calculation steps are as follows:

[0067] S201. Arrange the wind power and photovoltaic output data during the analysis period from large to small to obtain the array shown in the following formula:

[0068] (3)

[0069] (4)

[0070] Where, It represents the array of wind power historical operation data arranged from large to small during the analysis period. Represents an array Middle i data, the number of historical data selected is ; Represents an array of photovoltaic historical operating data arranged from large to small during the analysis period. Represents an array Middle j data, the number of historical data selected is .

[0071] S102. Considering the 95% confidence interval, select the 95% data in the two arrays and calculate the wind power output coefficient respectively. and photovoltaic output coefficient , the expression is as follows:

[0072] (5)

[0073] (6)

[0074] Where, Represents an array of wind power output data arranged from large to small In the middle, 95% of the data; Represents an array of photovoltaic output data arranged from large to small In the middle, 95% of the data; It represents the installed capacity of wind turbines in the province; Represents the province’s photovoltaic installed capacity.

[0075] For conventional thermal power units and hydropower units, under a given grid operation mode, based on the installed capacity of the units and taking spinning reserve into account, there are corresponding output coefficient values, expressed as follows:

[0076] (7)

[0077] (8)

[0078] Where, Indicates the output power of thermal power unit, Indicates the output coefficient of the thermal power unit under a given operating mode, Indicates the installed capacity of thermal power plants; Indicates the output power of the hydropower unit. Indicates the output coefficient of the hydropower unit under a given operating mode, Indicates the installed capacity of the hydropower generator.

[0079] Step 3: Analyze the system's power and electricity surplus during off-peak load periods and the electricity shortage during peak load periods.

[0080] Under a given operating mode and without considering energy storage peak load regulation, the power and electricity surplus of the system during the off-peak load period are analyzed. The expressions are as follows:

[0081] (9)

[0082] (10)

[0083] Where, Indicates the system surplus power during the off-peak load period, Indicates the output of thermal power units during the off-peak load period. Indicates the output of hydropower units during the off-peak load period. Indicates the output of new energy during the off-peak load period. Indicates the UHVDC input power during off-peak load period, Indicates the AC interconnection line power during the off-peak load period, Indicates the load during the off-peak load period; Indicates the power surplus during off-peak load period. Indicates the start time of the low load period. represents the end time of the off-peak load period, and formula (10) represents the chargeable amount of energy storage when there is a power surplus during the off-peak load period.

[0084] Considering the charging and discharging characteristics of energy storage, in order to ensure that the energy storage can still participate in peak load regulation and absorb surplus electricity during the off-peak load period the next day, it is necessary to ensure that the energy charged during the off-peak load period of the previous day can be released during the peak load period of the same day. The expression for the energy shortage during the peak load period is as follows:

[0085] (11)

[0086] (12)

[0087] Where, Indicates power shortage during peak load period. Indicates the output of thermal power units during peak load periods. Indicates the output of hydropower units during peak load period. Indicates the output of new energy during peak load period. Indicates the UHVDC power during peak load period, Indicates the AC tie line power during peak load period, Indicates the load during peak load period; Indicates the power shortage during peak load period. Indicates the start time of the peak load period, Indicates the end time of the peak load period.

[0088] Step 4: Calculate the energy storage capacity based on the constraints that the energy storage configuration capacity must meet, and propose energy storage demand indicators and energy storage development margin indicators based on the actual energy storage capacity of the power grid to evaluate the current and future energy storage development status of the power grid.

[0089] In order to meet the requirements of safe and stable operation of the power grid and power balance, the energy storage configuration capacity must meet the following constraint expressions:

[0090] (13)

[0091] (14)

[0092] (15)

[0093] Formula (13) indicates that the energy storage capacity needs to be able to meet the power shortage demand of the system during peak load periods, and formula (14) indicates that the energy storage charging capacity needs to meet the power shortage demand during peak load periods; Indicates the energy storage capacity, Indicates the maximum charge and discharge power of energy storage, Indicates the charging and discharging time of the maximum power of the energy storage; Formula (15) indicates that the chargeable amount during the off-peak load period must be greater than or equal to the power shortage during the peak load period. Indicates the energy storage charging and discharging efficiency.

[0094] The energy storage capacity obtained based on the above analysis It can meet the power balance requirements under a given operating mode and improve the peak load regulation capability of the power grid. , propose energy storage demand indicators and energy storage development margin indicators The expression is as follows:

[0095] (16)

[0096] (17)

[0097] Where, Indicates the actual energy storage capacity of the power grid, represents the energy storage demand index, represents the energy storage development margin index, It indicates that the new capacity of energy storage is planned every year according to demand. This value can be known through the power balance analysis in future years.

[0098] Energy storage demand indicators A value greater than 1 indicates that the grid energy storage capacity configuration can meet the power balance of the grid under a given operating mode, which is conducive to the safe and stable operation of the grid. If the value is less than 1, it means that the energy storage capacity configuration cannot meet the power and electricity balance under the given system operation mode, which will lead to an imbalance in power and electricity. When it is greater than 1, it indicates that the current system energy storage configuration capacity can adapt to future load development and meet the power balance needs of the power grid. When the value is less than 1, it indicates that the development of energy storage needs to be accelerated and the system energy storage capacity needs to be increased. The larger the value, the more the existing energy storage capacity can meet the development needs and is conducive to the power balance of the system.

[0099] Example:

[0100] Taking the operation of a provincial power grid on a typical high-load day in 2023 as an example, we analyze the system's power balance in 2023. The system curve for this provincial power grid on a typical high-load day in 2023 is shown in the figure below, with 15-minute intervals. Since high-load conditions typically occur at night, the photovoltaic output coefficient is 0 during this time. The wind power output coefficient is calculated based on historical operating data and is 0.34.

[0101] Under initial conditions, the maximum output of the thermal power plant is 24,000MW, and the full factor curve of the system is as follows: Figure 1 shown.

[0102] Will Figure 1 The output of the units shown is simplified, and the required power generation load curve of the system after deducting the output of hydropower, new energy, AC / DC interconnection lines, and gas-fired power generation is as follows: Figure 2 shown.

[0103] Depend on Figure 2 It can be seen that the maximum power shortage of the system during peak load period is 1920MW, that is The maximum power surplus during off-peak load period is 3350MW, .

[0104] The system's existing energy storage capacity is 4000MW. Based on the maximum power shortage during peak load periods, the initial energy storage capacity is configured to be at least 1920MW, which can meet the power balance constraint during peak load periods. However, the power balance constraint also needs to be met. Therefore, the energy storage conversion efficiency is considered based on the power shortage during peak load periods. The energy storage configuration capacity is 3320MW. Therefore, the corresponding index values ​​are calculated as follows:

[0105]

[0106]

[0107] The calculated index values ​​indicate that the region's energy storage capacity meets the grid's demand for energy storage participation in power balance analysis in 2023, while also being well-suited to future grid development.

Claims

1. A method for evaluating energy storage demand based on provincial power grid power balance, characterized in that: The steps include: Step 1: Establish the provincial power grid power balance constraint equation; the specific operations are as follows: The power balance constraint of the provincial power grid is as follows: （1）； Where, Indicates the output power of thermal power unit; Indicates the output power of the hydropower unit; Indicates the output power of new energy; Indicates the UHVDC input power; Indicates the power of the inter-provincial AC tie line. A positive value indicates input power, and a negative value indicates output power, i.e., power transmitted to other provinces. Indicates the energy storage output power. When the value is positive, it indicates that the energy storage is in a discharging state, and when it is negative, it indicates that the energy storage is in a charging state. Indicates the system load power; The output power of renewable energy is related to the output coefficient of renewable energy and the installed capacity of renewable energy, as shown in the following formula: （2）； Where, Indicates the output coefficient of wind turbines in the province, Indicates the installed capacity of wind turbines in the province, Indicates the photovoltaic output coefficient of the province, represents the province’s installed photovoltaic capacity; Step 2: Based on the historical operation data of the power grid, analyze the output coefficients of the new energy units under different operation modes; under a given operation mode of the power grid, based on the installed capacity of the units, analyze and obtain the output coefficients of conventional thermal power units and hydropower units; The output coefficients of new energy units include wind power and photovoltaic output coefficients. The calculation steps are as follows: S201. Arrange the wind power and photovoltaic output data during the analysis period from large to small to obtain the array shown in the following formula: （3）； （4）； Where, It represents the array of wind power historical operation data arranged from large to small during the analysis period. Represents an array Middle i data, the number of historical data selected is ; Represents an array of photovoltaic historical operating data arranged from large to small during the analysis period. Represents an array Middle j data, the number of historical data selected is ; S102. Considering the 95% confidence interval, select the 95% data in the two arrays and calculate the wind power output coefficient respectively. and photovoltaic output coefficient , the expression is as follows: （5）； （6）； Where, Represents an array of wind power output data arranged from large to small In the middle, 95% of the data; Represents an array of photovoltaic output data arranged from large to small In the middle, 95% of the data; It represents the installed capacity of wind turbines in the province; represents the province’s installed photovoltaic capacity; Step 3: Based on the provincial power grid power balance constraint equation, analyze the system power and electricity surplus during off-peak load periods and the electricity shortage during peak load periods; Step 4: Calculate the energy storage capacity based on the constraints that the energy storage configuration capacity must meet, and propose energy storage demand indicators and energy storage development margin indicators based on the actual energy storage capacity of the power grid to evaluate the current and future energy storage development status of the power grid.

2. The energy storage demand assessment method based on provincial power grid power balance according to claim 1 is characterized in that: In step 2, for conventional thermal power units and hydropower units, under a given grid operation mode, based on the installed capacity of the units and taking spinning standby into account, there are corresponding output coefficient values, expressed as follows: （7）； （8）； Where, Indicates the output power of thermal power unit, Indicates the output coefficient of the thermal power unit under a given operating mode, Indicates the installed capacity of thermal power plants; Indicates the output power of the hydropower unit. Indicates the output coefficient of the hydropower unit under a given operating mode, Indicates the installed capacity of the hydropower generator.

3. The energy storage demand assessment method based on provincial power grid power balance according to claim 1, characterized in that: In step 3, under a given operating mode and without considering energy storage peak load regulation, the power and power surplus of the system during the off-peak load period are analyzed, and the expression is as follows: （9）； （10）； Where, Indicates the system surplus power during the off-peak load period, Indicates the output of thermal power units during the off-peak load period. Indicates the output of hydropower units during the off-peak load period. Indicates the output of new energy during the off-peak load period. Indicates the UHVDC input power during off-peak load period, Indicates the AC interconnection line power during the off-peak load period, Indicates the load during the off-peak load period; Indicates the power surplus during off-peak load period. Indicates the start time of the low load period. represents the end time of the off-peak load period, and formula (10) represents the chargeable amount of energy storage when there is a power surplus during the off-peak load period.

4. The energy storage demand assessment method based on provincial power grid power balance according to claim 3 is characterized in that: In step 3, the expression for the power shortage during the peak load period is as follows: （11）； （12）； Where, Indicates power shortage during peak load period. Indicates the output of thermal power units during peak load periods. Indicates the output of hydropower units during peak load period. Indicates the output of new energy during peak load period. Indicates the UHVDC power during peak load period, Indicates the AC tie line power during peak load period, Indicates the load during peak load period; Indicates the power shortage during peak load period. Indicates the start time of the peak load period, Indicates the end time of the peak load period.

5. The energy storage demand assessment method based on provincial power grid power balance according to claim 4 is characterized in that: In step 4, the constraint expression that the energy storage configuration capacity must satisfy is as follows: （13）； （14）； （15）； Formula (13) indicates that the energy storage capacity needs to be able to meet the power shortage demand of the system during peak load periods, and formula (14) indicates that the energy storage charging capacity needs to meet the power shortage demand during peak load periods; Indicates the energy storage capacity, Indicates the maximum charge and discharge power of energy storage, Indicates the charging and discharging time of the maximum power of the energy storage; Formula (15) indicates that the chargeable amount during the off-peak load period must be greater than or equal to the power shortage during the peak load period. Indicates the energy storage charging and discharging efficiency.

6. The energy storage demand assessment method based on provincial power grid power balance according to claim 5, characterized in that: In step 4, the energy storage demand index and energy storage development margin indicators The expression is as follows: （16）； （17）； Where, Indicates the actual energy storage capacity of the power grid, represents the energy storage demand index, represents the energy storage development margin index, It indicates that the new capacity of energy storage is planned every year according to demand. This value can be known through the power balance analysis in future years.

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