Power system frequency safety support capability assessment method considering multi-resource differentiation

Abstract

The invention relates to a power system frequency safety support capability evaluation method considering multi-resource differentiation, and belongs to the technical field of power system frequency stability analysis. Comprising the steps that an electricity market clearing model is constructed, and the model comprises a target function with the minimum system fuel consumption as the target and set constraint conditions; calculating first fuel consumption of each thermal power generating unit and stored energy and first total fuel consumption of the system based on the power market clearing model; setting the frequency modulation capacity or inertia of the thermal power generating unit or the stored energy to be evaluated to be zero, and recalculating based on the power market clearing model to obtain the second total fuel consumption of the system; and based on the first total fuel consumption of the system, the second total fuel consumption of the system and the first fuel consumption of the to-be-evaluated thermal power generating unit or energy storage, calculating to obtain the safety support capability of the corresponding frequency modulation capacity or inertia to the frequency of the power system. The method accurately reflects the actual supporting capability of different resources for the frequency safety of the power system through calculation, and provides strategy support for optimizing frequency modulation resources of the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of power system frequency stability analysis, and in particular to a method for evaluating the frequency security support capability of a power system taking into account multi-resource differentiation. Background Art

[0002] In recent years, the proportion of wind and solar power installed capacity in the power system has steadily increased. New energy sources such as wind and solar power will become indispensable power supply resources, alleviating energy shortages and mitigating the adverse effects of climate change. However, the continued investment in wind and solar power presents new challenges to system security, with frequency security at all levels of power grids (including large-scale ones) being a prominent issue. First, wind and solar power generation is often connected to the grid via inverters, effectively decoupling from the grid and failing to effectively provide system inertia and frequency regulation support. This results in reduced system inertia and weakened interference immunity, making dynamic frequency security issues in new power systems increasingly prominent. Conventional operation and control methods based on the assumption of abundant inertia may present new problems and risks in low-inertia power systems. Second, the low marginal cost of new energy generators has led to a continuous decline in market electricity clearing prices. Energy-intensive generators, such as thermal power, are facing a significant decline in electricity revenue due to the dual pressures of declining utilization hours and falling electricity prices. Some generators, facing losses, have withdrawn from the market prematurely, further reducing the system's synchronous inertia and frequency regulation capacity. The inertia time constant of power systems in various countries has gradually decreased and is likely to continue to decline in the future. This will accelerate the rate of change of frequency (RoCoF) of the system at the moment of power disturbance, increase frequency deviation, affect the dynamic frequency security of the system, and even cause large-scale power outages. Therefore, the frequency security issue of new power systems needs to be urgently addressed.

[0003] The volatility and uncertainty of output from renewable energy generators (including wind and photovoltaic power generation) creates disturbances, necessitating more flexible resources to ensure the system's ability to regulate and respond to various emergencies. Currently, thermal power remains the most secure and reliable flexible regulation resource, but as the proportion of renewable energy increases, its frequency regulation capacity is limited. Therefore, while promoting the provision of flexible regulation resources for high-energy-consuming generators like thermal power, new technical approaches are also being actively developed. The introduction of multiple flexible resources complicates system frequency fluctuations. The coupling between energy, inertia, and frequency regulation capacity among these multiple resources increases the complexity of resource allocation and decision-making. Therefore, how to account for the coupling between inertia and frequency regulation capacity during dynamic system frequency fluctuations, while balancing system security, considering the technical characteristics of different resources in the frequency regulation process, and accurately quantifying their contribution to the frequency regulation process are key issues in ensuring system dynamic frequency security. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to disclose a method for evaluating the frequency security support capability of a power system that takes into account the differentiation of multiple resources. By constructing a power market clearing model to calculate the fuel consumption of each unit and system, and adopting a substitution concept based on the clearing model to recalculate the fuel consumption of the system when the thermal power unit or energy storage to be evaluated does not provide inertia or frequency regulation capacity, the method ultimately calculates the security support capability of different thermal power units and energy storage to provide inertia or frequency regulation capacity to the power system.

[0005] The present invention provides a method for evaluating the frequency security support capability of a power system taking into account the differentiation of multiple resources, which specifically includes the following steps:

[0006] S1. Construct an electricity market clearing model, including the objective function and constraints with the goal of minimizing the total fuel consumption of the system;

[0007] S2. Calculate, based on the electricity market clearing model, the first fuel consumption of each thermal power unit and energy storage unit and the first total fuel consumption of the system;

[0008] S3. Setting the frequency regulation capacity or inertia time constant of the thermal power unit or energy storage unit to be evaluated to zero, and recalculating the second total fuel consumption of the system based on the electricity market clearing model;

[0009] S4. Based on the first total fuel consumption of the system, the second total fuel consumption of the system, and the first fuel consumption of the thermal power unit or energy storage to be evaluated, calculate the frequency regulation capacity or inertia corresponding to the unit to ensure safe support of the power system frequency.

[0010] Furthermore, the objective function is constructed based on the output of each thermal power unit and the frequency regulation capacity of each thermal power unit; the set constraints include frequency safety constraints; and the inertia is the synchronous inertia of the thermal power unit or the virtual inertia of energy storage.

[0011] Furthermore, the set constraints also include: node power balance constraints, constraints on inertia and frequency regulation capacity provided by thermal power units, constraints on inertia provided by energy storage, constraints on frequency regulation capacity provided by energy storage, thermal power unit operation constraints, energy storage operation constraints, wind turbine operation constraints, and transmission line capacity constraints.

[0012] Furthermore, the frequency regulation capacity or inertia provided by the thermal power unit to be evaluated and the energy storage to be evaluated, calculated based on the first total fuel consumption of the system, the second total fuel consumption of the system, and the first fuel consumption of the thermal power unit to be evaluated or the energy storage to be evaluated, includes:

[0013]

[0014] in, Indicates the frequency regulation capacity or inertia of the thermal power unit or energy storage unit to be evaluated for its ability to safely support the power system frequency; represents the total second fuel consumption of the system calculated when the frequency regulation capacity or inertia of the thermal power unit or energy storage d to be evaluated is set to zero; represents the first fuel consumption of the thermal power unit or energy storage d to be evaluated; C F (X) represents the total first fuel consumption of the system.

[0015] Furthermore, the objective function is expressed as:

[0016]

[0017] Among them, C total Indicates the total fuel consumption of the system; Φ G , Φ T Respectively represent the thermal power unit set and the total number of time periods; v i,t represents the start and stop status of thermal power unit i in time period t; P i,t 、 They represent the output and frequency regulation capacity of thermal power unit i in time period t; a i 、b i 、c i They represent the coal consumption coefficient of thermal power unit i respectively.

[0018] Furthermore, the frequency safety constraint is expressed as:

[0019]

[0020] in, They represent the inertia provided by all thermal power units and all energy storage units during period t respectively; represents the system power disturbance, Δf represents the system frequency change value, Δf max Indicates the maximum limit of system frequency change; They represent the frequency regulation capacity provided by all energy storage and all thermal power units during period t respectively; Indicates the upper limit of the frequency change rate, and f0 indicates the rated frequency of the system.

[0021] Furthermore, the constraints on the inertia and frequency regulation capacity provided by the thermal power unit are expressed as:

[0022]

[0023] in, represents the synchronous inertia provided by all thermal power units during period t; v i,t represents the start and stop status of thermal power unit i in time period t; T i represents the inertia time constant of unit i; Respectively represent the upper and lower limits of the output of thermal power unit i; Pi,t represents the output of thermal power unit i in time period t; represents the primary frequency regulation capacity of thermal power unit i; Represents the upper limit of frequency regulation of thermal power unit i.

[0024] Furthermore, the energy storage provides an inertia constraint of:

[0025]

[0026] in, represents the virtual inertia of energy storage e in period t, T e represents the inertia time constant of stored energy, They represent the inertial support power and maximum charge and discharge power of the energy storage e in time period t respectively.

[0027] Furthermore, the frequency regulation capacity constraint provided by the energy storage is expressed as:

[0028]

[0029] in, They represent the frequency modulation capacity and discharge power of energy storage e in time period t respectively; represents the maximum charge and discharge power of energy storage e in time period t; represents the discharge state of energy storage e in time period t; k e represents the frequency regulation capacity factor of energy storage e; It represents the inertial support power of energy storage e in time period t.

[0030] Furthermore, the node power balance constraint is expressed as:

[0031]

[0032] in, Represent the wind power, thermal power generation, energy storage and load collection at node n respectively; P w,t represents the power generated by wind turbine w in time period t; They represent the charging and discharging power of the energy storage e in time period t respectively; fr(l) = n, to(l) = n represent the directed line l with the starting point and terminal point n respectively; P j,t represents the power of load j in time period t; P l,t represents the line transmission power of line l in time period t; P i,t Represents the output of thermal power unit i in time period t.

[0033] The present invention can achieve at least one of the following beneficial effects:

[0034] By using substitution calculations, the power system's frequency security support capacity is calculated, accurately quantifying the contribution of different thermal power units and energy storage systems to frequency security support. By minimizing total fuel consumption, the output of various resources is optimized, achieving optimal coordinated operation between traditional thermal power units, wind turbines, and new energy storage systems.

[0035] By comprehensively considering fuel consumption and resource allocation for system safety, the allocation strategy for frequency regulation resources can be optimized, prioritizing the use of units with higher fuel efficiency or units that consume less fuel in frequency regulation, significantly reducing fuel consumption while ensuring system frequency safety. Frequency regulation participation by units with high fuel consumption can be reduced, while encouraging low-fuel consumption units or units with higher fuel efficiency to participate in frequency regulation, thereby reducing carbon emissions and improving system flexibility.

[0036] Other features and advantages of the present invention will be described in the following description, and some advantages may become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0038] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0040] An embodiment of the present invention discloses a method for evaluating the frequency security support capability of a power system taking into account multi-resource differentiation, which specifically includes steps S1 to S4.

[0041] S1. Construct an electricity market clearing model, including an objective function with the goal of minimizing the total fuel consumption of the system and set constraints.

[0042] Specifically, the system includes thermal power units, energy storage, and wind power units. Since energy storage and wind power do not consume fuel, the objective function is constructed based on the output of each thermal power unit and the frequency regulation capacity of each thermal power unit. The objective function is expressed as:

[0043]

[0044] Among them, C totalIndicates the total fuel consumption of the system; Φ G , Φ T Respectively represent the thermal power unit set and the total number of time periods; v i,t represents the start and stop status of thermal power unit i in time period t; P i,t 、 They represent the output and frequency regulation capacity of thermal power unit i in time period t; a i 、b i 、c i They represent the coal consumption coefficient of thermal power unit i respectively.

[0045] Specifically, the set constraints include: frequency security constraints, node power balance constraints, constraints on the inertia and frequency regulation capacity provided by thermal power units, constraints on the inertia provided by energy storage, constraints on the frequency regulation capacity provided by energy storage, thermal power unit operation constraints, energy storage operation constraints, wind turbine operation constraints, and transmission line capacity constraints.

[0046] The frequency safety constraint is expressed as:

[0047]

[0048] in, They represent the inertia provided by all thermal power units and all energy storage units during period t respectively; represents the system power disturbance, Δf represents the system frequency change value, Δf max Indicates the maximum limit of system frequency change; They represent the frequency regulation capacity provided by all energy storage and all thermal power units during period t respectively; Indicates the upper limit of the frequency change rate, and f0 indicates the rated frequency of the system.

[0049] By setting frequency safety constraints, the power system frequency can be prevented from dropping too quickly when a large power imbalance occurs, thereby avoiding system collapse, improving the power system's resistance to various disturbances, and enhancing the stability of the power system; various resources in the power system, including the frequency regulation resources of thermal power units and energy storage, can be more reasonably allocated and dispatched, thereby improving the overall efficiency of the system.

[0050] The following describes the derivation process of the frequency safety constraint:

[0051] When a power disturbance occurs, the relationship between the system frequency change and the inertia, frequency modulation capacity, and power disturbance magnitude can be expressed as:

[0052]

[0053] Different frequency modulation resources have different response times and a certain coupling relationship exists between them, which can be expressed as follows:

[0054]

[0055] Among them, T1 and T2 represent the ramp time constants of energy storage and thermal power generation units respectively, T del1 、T del2 They represent the frequency regulation delay time of energy storage and thermal power units respectively.

[0056] Based on formulas (1) and (2), the frequency safety constraint can be expressed in three aspects, including frequency change rate constraint, frequency minimum point constraint and quasi-steady-state frequency constraint.

[0057] Furthermore, the frequency change rate constraint is described as follows:

[0058] At the moment of disturbance, the system frequency does not change and all frequency modulation resources do not respond, so at this time Δf is (The frequency modulation capacity provided by all frequency modulation resources) is 0, only the inertia instantaneous action, the system frequency change rate RoCoF is the largest. To ensure that the system RoCoF is within the limit, it is necessary to ensure that the RoCoF when the system is disturbed is less than its upper limit. The frequency change rate constraint can be expressed as:

[0059] Furthermore, the frequency minimum point constraint is described as follows:

[0060] The frequency change can be expressed as:

[0061]

[0062] The lowest frequency point appears after the frequency modulation response of the thermal power unit, that is, [T del2 , T del2 +T2], when Δf / Δt = 0, it is the time of the lowest frequency point, which can be expressed as:

[0063]

[0064] Substituting the lowest frequency point time into the frequency change formula, we can get:

[0065]

[0066] To ensure that the lowest frequency point of the system is within the allowable range, the frequency safety needs to satisfy the formula: |Δf|≤|Δf max |.

[0067] Furthermore, the quasi-steady-state frequency constraint is described as follows:

[0068] When the system frequency reaches its lowest point, the system frequency can only be restored to normal range by relying on the thermal power units and energy storage to participate in frequency regulation. Therefore, the frequency regulation capacity provided by the thermal power units and energy storage must be sufficient to offset the unbalanced power of the system and ensure that the frequency recovers stably. tEFR +P t PFR ≥P t Loss .

[0069] The above is an explanation of the principle of frequency safety constraints.

[0070] The node power balance constraint is expressed as:

[0071]

[0072] in, They represent the wind turbine, thermal power plant, energy storage and load at node n respectively; P w,t represents the power generated by wind turbine w in time period t; They represent the charging and discharging power of the energy storage e in time period t respectively; fr(l) = n, to(l) = n represent the directed line l with the starting point and terminal point n respectively; P j,t represents the power of load j in time period t; P l,t represents the line transmission power of line l in time period t; P i,t represents the output of thermal power unit i in time period t. The node power balance constraint means that the system must always ensure the balance between supply and demand to avoid insufficient or excessive power generation.

[0073] The constraints on the inertia and frequency regulation capacity provided by thermal power units are expressed as:

[0074]

[0075] in, represents the synchronous inertia provided by all thermal power units during period t; v i,t represents the start and stop status of thermal power unit i in time period t; T i represents the inertia time constant of unit i; Respectively represent the upper and lower limits of the output of thermal power unit i; P i,t represents the output of thermal power unit i in time period t; represents the primary frequency regulation capacity of thermal power unit i; Represents the upper limit of frequency regulation of thermal power unit i.

[0076] Furthermore, the principle behind the constraints on inertia and frequency regulation capacity provided by thermal power units is as follows: From a time perspective, inertia can be defined as the duration of time a generator unit can supply power to a rated load through stored kinetic energy. This is the inertia constant H, measured in seconds. The same time parameter is the inertia time constant T, which represents the time it takes for the generator rotor to go from a stationary state to a rated state under rated torque. The relationship between the two is T = 2H. From an energy perspective, in a multi-machine power system, units that can provide inertia can be considered equivalent synchronous generators. When a thermal power unit is started and operating, it can provide a certain amount of inertia and primary frequency regulation capacity, but the frequency regulation capacity must not exceed the upper limit, and the output of a single thermal power unit cannot exceed its maximum output limit.

[0077] The inertia constraint provided by energy storage is expressed as:

[0078]

[0079] in, represents the virtual inertia of energy storage e in period t, T e represents the inertia time constant of stored energy, They represent the inertial support power and maximum charge and discharge power of the energy storage e in time period t respectively; represents the upper limit of the frequency change rate, and f0 represents the rated system frequency. The constraints on the inertia provided by energy storage and its supported power indicate that there is a certain coupling relationship between energy storage output power and inertia, and providing inertia requires reserved discharge power.

[0080] The frequency regulation capacity constraint provided by energy storage is expressed as:

[0081]

[0082] in, They represent the frequency modulation capacity and discharge power of energy storage e in time period t respectively; represents the maximum charge and discharge power of energy storage e in time period t; represents the discharge state of energy storage e in time period t; k e represents the frequency regulation capacity factor of energy storage e; It represents the inertial support power of energy storage e in time period t.

[0083] It's important to note that energy storage frequency regulation has a response time of hundreds of milliseconds, a full response time shorter than that of thermal power units, enabling faster response to system frequency changes. The frequency regulation capacity constraint provided by energy storage means that the frequency regulation capacity provided by energy storage cannot exceed a limit. The energy storage discharge power, inertia support power, and frequency regulation capacity cannot exceed the maximum discharge power.

[0084] The ramping and start-stop time constraints of thermal power units are expressed as:

[0085]

[0086] in, They represent the upper and lower climbing limits of thermal power unit i respectively. Indicates the startup and shutdown time of thermal power unit i in time period t; Indicates the minimum startup and shutdown time limits of thermal power unit i.

[0087] The energy storage operation constraints are expressed as:

[0088]

[0089] in, They represent the charging power and charging state of the energy storage e in time period t respectively; represents the stored energy of energy storage e in time period t, represents the energy storage e charging and discharging efficiency, Δt represents the scheduling period; Indicates the maximum and minimum storage energy of the energy storage e.

[0090] The wind turbine operation constraints are expressed as:

[0091]

[0092] Among them, P w,t represents the power generated by wind turbine w in time period t, Represents the predicted output of wind turbine w in time period t.

[0093] The transmission line capacity constraint is expressed as:

[0094]

[0095] where x l Represents the reactance value of line l; θ l∈Fn ,θ l∈Ln They represent the phase angles with respect to the node n where the starting point and the terminal point of line l are located respectively; Indicates the maximum transmission capacity of line l.

[0096] S2. Calculate the first fuel consumption of each thermal power unit and energy storage and the first total fuel consumption of the system based on the electricity market clearing model.

[0097] Specifically, during the solution, based on the objective function and set constraints, the load curve and wind power output curve are used as inputs, and a solver is used to solve the electricity market clearing model to obtain the first fuel consumption of each thermal power unit and energy storage unit and the first total fuel consumption of the system during the total time period. Exemplarily, the solution is performed using the Gurobi solver.

[0098] It should be noted that, since the energy storage and wind turbine generator sets do not consume fuel, the first fuel consumption of each energy storage and wind turbine generator set is zero.

[0099] The calculation method of the first total fuel consumption of the system is:

[0100]

[0101] S3. The frequency regulation capacity or inertia time constant of the thermal power unit or energy storage to be evaluated is set to zero, and a second total fuel consumption of the system is recalculated based on the electricity market clearing model.

[0102] In step S3, a substitution concept is employed, where the frequency regulation capacity or inertia time constant of the thermal power unit or energy storage unit to be evaluated is set to zero. This means that in this step, the frequency regulation capacity or inertia (the inertia time constant is proportional to the inertia) of the thermal power unit or energy storage unit to be evaluated does not contribute to the safety support of the power system. The inertia is the synchronous inertia of the thermal power unit or the virtual inertia of the energy storage unit.

[0103] When resolving, based on the objective function and the set constraints, the load curve and the wind power output curve are used as input, and the solver is used to solve the electricity market clearing model again to obtain the second total fuel consumption of the system in the total period.

[0104] S4. Based on the first total fuel consumption of the system, the second total fuel consumption of the system, and the first fuel consumption of the thermal power unit or energy storage to be evaluated, calculate the frequency regulation capacity or inertia of the unit to ensure safe support of the power system frequency.

[0105] In steps S2 and S3, the cases where the thermal power unit or energy storage to be evaluated provides or does not provide frequency regulation capacity or inertia to the power system are solved respectively. The calculation formula for the frequency regulation capacity or inertia provided by the thermal power unit or energy storage to be evaluated to support the power system frequency security is:

[0106]

[0107] in, Indicates the frequency regulation capacity or inertia of the thermal power unit or energy storage unit to be evaluated for its ability to safely support the power system frequency; represents the total second fuel consumption of the system calculated when the frequency regulation capacity or inertia of the thermal power unit or energy storage d to be evaluated is set to zero; represents the first fuel consumption of the thermal power unit or energy storage d to be evaluated; C F (X) represents the total first fuel consumption of the system, that is, the system fuel consumption when all units participate in market clearing.

[0108] final The frequency regulation capacity or inertia of the thermal power unit or energy storage d to be evaluated is the safe support capability of the power system frequency, that is, the quantitative expression of the contribution size. A large value indicates a large contribution and a strong ability to support the security of the power system frequency. This is because when the thermal power unit or energy storage does not provide the corresponding inertia or frequency regulation capacity, other resources need to consume more fuel to make up for the missing inertia or frequency regulation capacity.

[0109] This embodiment discloses a method for assessing the frequency security support capability of a power system, taking into account the differentiation of multiple resources. This method uses substitution to calculate the frequency security support capability of the power system, accurately quantifying the contribution of different thermal power units and energy storage systems to frequency security support. By minimizing total fuel consumption, the output of various resources is optimized to achieve optimal coordinated operation between traditional thermal power units, new energy units, and new energy storage systems.

[0110] By comprehensively considering fuel consumption and resource allocation for system safety, frequency regulation resource allocation strategies can be optimized, prioritizing the use of thermal power units or energy storage with strong support for power system frequency security—that is, units with higher fuel efficiency or lower fuel consumption—in frequency regulation, significantly reducing system fuel consumption in the process of ensuring system frequency security. Frequency regulation participation by high-fuel-consuming units can be reduced, while encouraging low-fuel-consuming units or units with higher fuel efficiency to participate in frequency regulation, thereby reducing carbon emissions and improving system flexibility.

[0111] The above is only a preferred specific implementation of the present invention, but the scope of protection of the present invention is not limited to this. The objective function of the method of the present invention can be flexibly selected and customized according to the actual clearing situation, and the constraints can be added and deleted according to actual needs, and the scalability is strong; therefore, any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for evaluating the frequency security support capability of a power system taking into account the differentiation of multiple resources, characterized in that: The steps include: S1. Construct an electricity market clearing model, including the objective function and constraints with the goal of minimizing the total fuel consumption of the system; S2. Calculate, based on the electricity market clearing model, the first fuel consumption of each thermal power unit and energy storage unit and the first total fuel consumption of the system; S3. Setting the frequency regulation capacity or inertia time constant of the thermal power unit or energy storage unit to be evaluated to zero, and recalculating the second total fuel consumption of the system based on the electricity market clearing model; S4. Based on the first total fuel consumption of the system, the second total fuel consumption of the system, and the first fuel consumption of the thermal power unit or energy storage to be evaluated, calculate the frequency regulation capacity or inertia corresponding to the thermal power unit or energy storage for the safe support capability of the power system frequency.

2. The method for evaluating the frequency security support capability of a power system according to claim 1, characterized in that: The objective function is constructed based on the output of each thermal power unit and the frequency regulation capacity of each thermal power unit; the set constraints include frequency safety constraints; and the inertia is the synchronous inertia of the thermal power unit or the virtual inertia of energy storage.

3. The method for evaluating the frequency security support capability of a power system according to claim 2, characterized in that: The set constraints also include: node power balance constraints, constraints on inertia and frequency regulation capacity provided by thermal power units, constraints on inertia provided by energy storage, constraints on frequency regulation capacity provided by energy storage, thermal power unit operation constraints, energy storage operation constraints, wind turbine operation constraints and transmission line capacity constraints.

4. The method for evaluating the frequency security support capability of a power system according to claim 3, wherein: The frequency regulation capacity or inertia provided by the thermal power unit or energy storage to be evaluated, calculated based on the first total fuel consumption of the system, the second total fuel consumption of the system, and the first fuel consumption of the thermal power unit or energy storage to be evaluated, for the safe support capability of the power system frequency includes: in, Indicates the frequency regulation capacity or inertia of the thermal power unit or energy storage unit to be evaluated for its ability to safely support the power system frequency; represents the total second fuel consumption of the system calculated when the frequency regulation capacity or inertia of the thermal power unit or energy storage d to be evaluated is set to zero; represents the first fuel consumption of the thermal power unit or energy storage d to be evaluated; C F (X) represents the total first fuel consumption of the system, that is, the system fuel consumption when all units participate in market clearing.

5. The method for evaluating the frequency security support capability of a power system according to claim 4, characterized in that: The objective function is expressed as: Among them, C total Indicates the total fuel consumption of the system; Φ G , Φ T Respectively represent the thermal power unit set and the total number of time periods; v i,t represents the start and stop status of thermal power unit i in time period t; P i,t 、 They represent the output and frequency regulation capacity of thermal power unit i in time period t respectively; a i 、b i 、c i They represent the coal consumption coefficient of thermal power unit i respectively.

6. The method for evaluating the frequency security support capability of a power system according to claim 5, characterized in that: The frequency safety constraint is expressed as: in, They represent the inertia provided by all thermal power units and all energy storage units during period t respectively; represents the system power disturbance, Δf represents the system frequency change value, Δf max Indicates the maximum limit of system frequency change; They represent the frequency regulation capacity provided by all energy storage and all thermal power units during period t respectively; Indicates the upper limit of the frequency change rate, and f0 indicates the rated frequency of the system.

7. The method for evaluating the frequency security support capability of a power system according to claim 5, characterized in that: The constraints on the inertia and frequency regulation capacity provided by the thermal power unit are expressed as: in, represents the synchronous inertia provided by all thermal power units during period t; v i,t represents the start and stop status of thermal power unit i in time period t; T i represents the inertia time constant of unit i; Respectively represent the upper and lower limits of the output of thermal power unit i; P i,t represents the output of thermal power unit i in time period t; represents the primary frequency regulation capacity of thermal power unit i; Indicates the upper limit of frequency regulation of thermal power unit i.

8. The method for evaluating the frequency security support capability of a power system according to claim 5, characterized in that: The energy storage provides inertia constraint expressed as: in, represents the virtual inertia of energy storage e in period t, T e represents the inertia time constant of stored energy, They represent the inertial support power and maximum charge and discharge power of the energy storage e in time period t respectively. Indicates the upper limit of the frequency change rate, and f0 indicates the rated frequency of the system.

9. The method for evaluating the frequency security support capability of a power system according to claim 5, wherein: The frequency regulation capacity constraint provided by energy storage is expressed as: in, They represent the frequency modulation capacity and discharge power of energy storage e in time period t respectively; represents the maximum charge and discharge power of energy storage e in time period t; represents the discharge state of energy storage e in time period t; k e represents the frequency regulation capacity factor of energy storage e; It represents the inertial support power of energy storage e in time period t.

10. The method for evaluating the frequency security support capability of a power system according to claim 5, characterized in that: The node power balance constraint is expressed as: in, They represent the wind turbine, thermal power plant, energy storage and load at node n respectively; P w,t represents the power generated by wind turbine w in time period t; They represent the charging and discharging power of the energy storage e in time period t respectively; fr(l) = n, to(l) = n represent the directed line l with the starting point and terminal point n respectively; P j,t represents the power of load j in time period t; P l,t represents the line transmission power of line l in time period t; P i,t Represents the output of thermal power unit i in time period t.

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