Thermal power bottoming capacity evaluation method considering electric power and electric quantity balance and stable safety guarantee

Abstract

The invention relates to a thermal power underpinning capacity evaluation method considering electric power and electric quantity balance and stable safety guarantee, which comprises the following steps: establishing an evaluation model considering electric quantity balance, and carrying out preliminary evaluation on thermal power installed capacity; a thermal power installed capacity optimization evaluation model is established, the thermal power installed capacity is further evaluated, and a thermal power generating unit installation scheme set is generated; generating a lowest frequency point of the system based on a dynamic process of power system frequency response and by considering conventional thermal power active power frequency modulation; and the generated thermal power generating unit installation scheme set is screened, and a safe and stable thermal power underpinning capacity scheme meeting the system electric power and electric quantity balance is screened out. According to the method, the thermal power installed capacity meeting the system electric quantity balance constraint is optimized to serve as a preliminary scheme, and a thermal power generating unit installation scheme set is generated; and performing frequency verification on each thermal power installation scheme, analyzing the lowest point of the system frequency when the system is disturbed, and screening out a safe and stable thermal power bottoming capacity scheme meeting the power and electric quantity balance of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning and evaluation, and in particular to a method for evaluating the bottom-line capacity of thermal power plants taking into account power and electricity balance and stable safety assurance. Background Art

[0002] With economic development, energy consumption continues to grow. As a clean and renewable energy, new energy has rapidly increased its share in the global energy supply. New energy has the characteristics of environmental protection and low operating costs. Vigorously developing new energy has a good effect on alleviating the tense energy situation. The penetration rate of new energy in the power system has gradually increased, and traditional thermal power has also begun to transform from the main energy source to the bottom energy source. The role of conventional thermal power in the balance of power and electricity has gradually weakened, but it does not mean that the bottom thermal power capacity can be reduced synchronously. The supporting role of conventional thermal power for the safe and stable operation of the system still needs to be considered. At present, it is still unclear how to evaluate the bottom energy capacity required for the power grid at different stages.

[0003] At present, it is still unclear how to evaluate the bottom-line energy capacity required for the power grid at different stages. Due to the intermittent and random nature of new energy, there is a lack of accurate evaluation of the bottom-line capacity of thermal power units, and the power grid may not be able to maintain stable operation under various conditions. If the assessed capacity is too high, it may lead to waste of thermal power resources and increase the abandonment rate of new energy wind and solar power; if the assessed capacity is too low, if the power demand suddenly increases without a corresponding increase in energy capacity, it may lead to power shortages and affect normal power supply. Therefore, it is of great significance to accurately evaluate the bottom-line capacity of thermal power units. Summary of the invention

[0004] In order to solve the current problem of how to evaluate the bottom energy capacity required by the power grid at different stages, the purpose of the present invention is to provide a method for evaluating the bottom thermal power capacity that can meet the power balance and ensure the safe and stable operation of the system, clarify the minimum coal-fired power capacity required by the system in different development stages and its bottom-line role, and provide direction for exploring the supply and demand balance path at different development stages. The method takes into account the power balance and stable and safe guarantee of the thermal power bottom capacity evaluation.

[0005] To achieve the above object, the present invention adopts the following technical solution: a method for evaluating the bottom capacity of thermal power plants taking into account power and electricity balance and stable safety assurance, the method comprising the following steps in order:

[0006] (1) With the goal of maximizing the annual power surplus of each unit in the entire system, an evaluation model that considers power balance is established, a preliminary evaluation of thermal power installed capacity is conducted, and a preliminary thermal power installed capacity plan is generated;

[0007] (2) Based on the thermal power installed capacity pre-plan, with the goal of maximizing the annual power surplus of each unit in the entire system, an optimization evaluation model for thermal power installed capacity is established, and the thermal power installed capacity is further evaluated to generate a thermal power plan and an energy storage plan. The thermal power plan and the energy storage plan constitute a set of thermal power installed capacity plans;

[0008] (3) Based on the dynamic process of power system frequency response, taking into account the frequency modulation of conventional thermal power active power, the lowest frequency point f of the system is generated nadir ;

[0009] (4) Using the generated frequency minimum point f nadir The generated set of thermal power plant assembly unit plans is screened to select the thermal power bottom capacity plan that meets the system power balance and safety and stability.

[0010] The step (1) specifically comprises the following steps:

[0011] (1a) Establish the objective function for maximizing the annual power surplus of each unit in the entire system:

[0012]

[0013] In the formula, C G is the installed capacity of thermal power, T G is the annual utilization hours of thermal power, T G,max is the maximum annual utilization hours of thermal power, C WT is the installed capacity of wind power, T WT is the annual utilization hours of wind power, T WT,max is the maximum annual utilization hours of wind power, C PV is the photovoltaic installed capacity, T PV is the annual utilization hours of photovoltaic power, T PV,max is the maximum annual utilization hours of photovoltaic power generation, C SD is the installed capacity of hydropower, T SD is the annual utilization hours of hydropower, T SD,max is the maximum annual utilization hours of hydropower, C QY is the installed capacity of the remaining power sources, T QY is the annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of the remaining power supply, C YW is the installed capacity of DC power outside the region, T YW is the annual utilization hours of DC power outside the region, T YW,max E is the maximum annual utilization hours of DC power outside the region, load is the load power;

[0014] (1b) According to the carbon emission requirements, set carbon emission constraints for thermal power generators:

[0015] ξtan C G T G ≤C tan (2)

[0016] In the formula, ξ tan is the carbon emission coefficient of thermal power, C tan is the annual carbon emission threshold of the system;

[0017] (1c) Based on the power balance, establish the power balance constraint:

[0018] C G T G +C WT T WT +C PV T PV +C SD T SD +C QY T QY +C YW T YW -E chu ≥E load +E bei (3)

[0019] In the formula, E bei is the reserve power, E chu E is the power loss of energy storage charging and discharging, chu The formula is:

[0020] E chu =(P ch -P ch η ch )T ch +(P dis / η dis -P dis )T dis (4)

[0021] Where P ch is the energy storage charging power, η ch is the energy storage charging efficiency, T ch is the annual charging time of energy storage, P dis is the energy storage discharge power, η dis is the energy storage discharge efficiency, T dis is the annual discharge duration of energy storage;

[0022] (1d) Based on the power capacity, establish power capacity constraints:

[0023] C G,max ≥C G ≥C G,min (5)

[0024] CWT,max ≥C WT ≥C WT,min (6)

[0025] C PV,max ≥C PV ≥C PV,min (7)

[0026] C SD,max ≥C SD ≥C SD,min (8)

[0027] C QY,max ≥C QY ≥C QY,min (9)

[0028] C YW,max ≥C YW ≥C YW,min (10)

[0029] P ch,max ≥P ch ≥P ch,min (11)

[0030] P dis,max ≥P dis ≥P dis,min (12)

[0031] Formula to middle, C G,max is the maximum installed capacity of thermal power, C G,min is the minimum installed capacity of thermal power, C WT,max is the maximum installed capacity of wind power, C WT,min is the minimum installed capacity of wind power, C PV,max is the maximum installed capacity of photovoltaic power generation, C PV,min is the minimum installed capacity of photovoltaic power generation, C SD,max is the maximum installed capacity of hydropower, C SD,min is the minimum installed capacity of hydropower, C QY,max is the maximum installed capacity of the remaining power sources, C QY,min is the minimum installed capacity of the remaining power sources, C YW,max is the maximum installed capacity of DC power outside the region, C YW,min is the minimum installed capacity of DC power outside the region, P ch,max is the maximum charging power of energy storage, P ch,min is the minimum charging power of energy storage, P dis,max is the maximum discharge power of energy storage, P dis,min is the minimum discharge power of energy storage;

[0032] (1e) Based on the annual power utilization hours requirements, establish annual power utilization hours constraints:

[0033]

[0034] Where, T G,min is the minimum annual utilization hours of thermal power, T WT,min is the minimum annual utilization hours of wind power, T PV,min is the minimum annual utilization hours of photovoltaic power generation, T SD,min is the minimum annual utilization hours of hydropower, T SD,max is the maximum annual utilization hours of hydropower, T QY,min is the minimum annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of other power sources, T YW,min is the minimum annual utilization hours of DC power outside the region, T YW,max T is the maximum annual utilization hours of DC power outside the region, ch,max is the maximum annual charging hours of energy storage, T ch,min is the minimum annual charging hours for energy storage, T dis,max is the maximum annual discharge hours of energy storage, T dis,min is the minimum annual discharge hours of energy storage;

[0035] Formula (1) to Formula (13) together constitute an evaluation model that takes power balance into consideration.

[0036] The step (2) specifically comprises the following steps:

[0037] (2a) Taking the maximum annual power surplus of each unit in the entire system as the goal, the objective function is established:

[0038]

[0039] Where C' G To consider the thermal power capacity to balance the peak power, ξ G is the proportion of thermal power capacity included in the peak balance, ξ WT is the proportion of wind power capacity included in the peak balance, ξ PV is the proportion of photovoltaic capacity included in the peak balance, ξ SD is the proportion of hydropower capacity included in the peak balance, ξ QY The remaining power sources are included in the peak balance ratio, ξ YW The peak balance ratio of DC outside the region, ξ ch The peak balance ratio of energy storage is P load is the maximum load in a year, N t is the number of hours in a year, N G is the number of thermal power installed units, P G,max is the maximum output of thermal power G, P G,t is the output of thermal power G at time t, P WT,t is the abandoned air volume at time t, P PV,t is the amount of abandoned light at time t, Pload,t is the load size at time t, P ch is the energy storage charging power, C WT is the installed capacity of wind power, C PV is the photovoltaic installed capacity, C SD is the installed capacity of hydropower, C QY is the installed capacity of the remaining power sources, C YW It is the DC installed capacity outside the region;

[0040] (2b) Based on the peak power balance, establish the peak power balance constraint:

[0041] C' G ξ G +C WT ξ WT +C PV ξ PV +C SD ξ SD +C QY ξ QY +C YW ξ YW +P ch ξ ch ≥P load +P bei (15)

[0042] Where P bei Provides backup power capacity for the system;

[0043] (2c) Based on the installed capacity of thermal power, establish the thermal power installed capacity constraints:

[0044] C' G,max ≥C' G ≥C' G,min (16)

[0045] Where C' G,max To consider the upper limit of thermal power capacity to balance peak power, C' G,min The lower limit of thermal power capacity to consider peak power balance;

[0046] (2d) According to the operation status of cluster units, establish output power constraints and unit climbing constraints:

[0047]

[0048]

[0049]

[0050] Where: represents the output upper limit of cluster unit g, Indicates the lower limit of the output of cluster unit g, is the ratio of the startup power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the shutdown power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the maximum upward climbing capacity of cluster unit g in unit time to the total operating capacity of the unit, is the ratio of the maximum downward ramping capacity of cluster unit g in unit time to the total operating capacity of the unit, O g,t represents the sum of the rated capacities of the online generating units of cluster unit g at time t, SU g,t-1 represents the sum of the rated capacities of the generating units that are planned to be started by cluster unit g at time t-1, SD g,t-1 represents the sum of the rated capacities of the generating units of cluster unit g that are scheduled to be shut down at time t-1, P g,t represents the sum of the rated capacities of all units in cluster unit g at time t;

[0051] (2e) Establish minimum start-stop time constraints:

[0052] 0≤SD g,1 ≤O g,0 (20)

[0053]

[0054]

[0055] 0≤SU g,1 ≤P g -O g,0 (twenty three)

[0056]

[0057]

[0058] Formula to middle: O g,0 is the online operating capacity of cluster unit g in the initial time period; UT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g; DT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g;

[0059] (2f) Establish output constraints for new energy sources:

[0060] P wr,t +P wa,t =P w,t (26)

[0061] P pr,t +P pa,t =P p,t (27)

[0062]

[0063] Where: P wr,t and P pr,t are the actual grid-connected outputs of wind power and photovoltaic power respectively; P wa,t and P pa,t are wind power and photovoltaic power abandonment respectively; P w,t and P p,t are the theoretical outputs of wind power and photovoltaic power respectively;

[0064] (2g) The energy storage operation constraints are:

[0065]

[0066] 0≤E t ≤E ESS (30)

[0067] 0≤P ch,t ≤P ESS (31)

[0068] 0≤P dis,t ≤P ESS (32)

[0069] 0≤P dis,t ≤β t M (33)

[0070] 0≤P ch,t ≤(1-β t )M (34)

[0071]

[0072]

[0073] In the formula, E t represents the capacity of energy storage at time t, η ch and η dis are the charging and discharging efficiency of energy storage, P ch,t and P dis,t are the charging and discharging power of energy storage respectively; E ESS Indicates the rated capacity of energy storage; P ESS Indicates the rated power of energy storage; β t is a variable of 0 or 1, 1 indicates that the energy storage is in a discharging state, and 0 indicates that the energy storage is in a charging state; M is a positive real number; SOC min Indicates the minimum state of charge of energy storage; SOC maxIndicates the maximum state of charge of the energy storage;

[0074] Equations (14) to (36) together constitute the optimization evaluation model for thermal power installed capacity.

[0075] The step (3) specifically comprises the following steps:

[0076] (3a) According to the swing equation, the dynamic frequency response of the power system is obtained:

[0077]

[0078] Where: Δf(t) is the frequency deviation; D is the load damping coefficient; ΔP G (t) is the increase in active power output of the thermal power unit under the condition of power generation loss ΔP; H eq is the total inertia time constant of the system;

[0079] (3b) The system power generation loss ΔP is taken as input and the frequency deviation Δf is taken as output to model the system. The transfer function is:

[0080]

[0081] In the formula, K i is the mechanical power gain factor; R i F is the static adjustment coefficient of thermal power unit; i is the fraction of the total power generated by the high pressure turbine; T i is the time constant of the thermal power unit speed regulator; ΔP(t) is the power loss of the system at time t, H G is the inertia time constant of the thermal power unit, s is the complex frequency in the Laplace domain;

[0082] (3c) The time constant T of different speed regulators i With the same value T R Instead, simplify the frequency domain expression of Δf:

[0083]

[0084] Where ξ is the damping ratio, ω f is the natural vibration frequency;

[0085] (3d) Using the inverse Laplace transform and taking the derivative of the time domain expression of Δf with respect to t, let dΔf(t) / dt = 0, and we can get the lowest frequency point f nadir As shown below:

[0086]

[0087] Where f0 is the reference frequency; t nadir is the time corresponding to the lowest frequency, RT is the total power-frequency static characteristic coefficient of the generator set, F is the fraction of the total power, and the calculation formula is as follows:

[0088]

[0089] The step (4) specifically refers to: determining the lowest frequency point f of the solution in the thermal power plant assembly solution set nadir Whether it meets the requirements, if the frequency is the lowest point f nadir Within the range of [49.8,50.2] Hz, it is determined that the solution is a thermal power capacity support solution that meets the system power balance and safe and stable.

[0090] It can be seen from the above technical scheme that the beneficial effects of the present invention are: first, based on the system power balance, the present invention considers the installed capacity and annual maximum utilization hours of different power sources, establishes an evaluation model considering power balance, and optimizes the thermal power installed capacity that meets the system power balance constraints as a preliminary plan; second, based on the system power balance, the present invention considers the peak power balance and the annual time sequence power balance on the basis of the thermal power pre-installed unit plan, establishes a thermal power installed capacity optimization evaluation model, and generates a set of thermal power unit assembly plans; third, from the perspective of ensuring the safe and stable operation of the system, the present invention performs frequency verification on each thermal power installation plan, considers frequency support, analyzes the lowest point of the system frequency when the system is disturbed, and screens out the thermal power bottoming capacity plan that meets the system power balance and safety and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0092] like Figure 1 As shown, a method for evaluating the thermal power capacity supporting capacity considering power and electricity balance and stability and safety assurance includes the following steps in order:

[0093] (1) With the goal of maximizing the annual power surplus of each unit in the entire system, an evaluation model that considers power balance is established, a preliminary evaluation of thermal power installed capacity is conducted, and a preliminary thermal power installed capacity plan is generated;

[0094] (2) Based on the thermal power installed capacity pre-plan, with the goal of maximizing the annual power surplus of each unit in the entire system, an optimization evaluation model for thermal power installed capacity is established, and the thermal power installed capacity is further evaluated to generate a thermal power plan and an energy storage plan. The thermal power plan and the energy storage plan constitute a set of thermal power installed capacity plans;

[0095] (3) Based on the dynamic process of power system frequency response, taking into account the frequency modulation of conventional thermal power active power, the lowest frequency point f of the system is generated nadir ;

[0096] (4) Using the generated frequency minimum point f nadir The generated set of thermal power plant assembly unit plans is screened to select the thermal power bottom capacity plan that meets the system power balance and safety and stability.

[0097] The step (1) specifically comprises the following steps:

[0098] (1a) Establish the objective function for maximizing the annual power surplus of each unit in the entire system:

[0099]

[0100] In the formula, C G is the installed capacity of thermal power, T G is the annual utilization hours of thermal power, T G,max is the maximum annual utilization hours of thermal power, C WT is the installed capacity of wind power, T WT is the annual utilization hours of wind power, T WT,max is the maximum annual utilization hours of wind power, C PV is the photovoltaic installed capacity, T PV is the annual utilization hours of photovoltaic power, T PV,max is the maximum annual utilization hours of photovoltaic power generation, C SD is the installed capacity of hydropower, T SD is the annual utilization hours of hydropower, T SD,max is the maximum annual utilization hours of hydropower, C QY is the installed capacity of the remaining power sources, T QY is the annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of the remaining power supply, C YW is the installed capacity of DC power outside the region, T YW is the annual utilization hours of DC power outside the region, T YW,max E is the maximum annual utilization hours of DC power outside the region, load is the load power; here, the remaining power sources refer to the power sources other than thermal power, wind power, photovoltaic power and hydropower, which use waste heat and waste gas to generate electricity; outside the domain refers to outside the entire system.

[0101] (1b) According to the carbon emission requirements, set carbon emission constraints for thermal power generators:

[0102] ξ tan C G T G ≤C tan (2)

[0103] In the formula, ξ tan is the carbon emission coefficient of thermal power, C tan is the annual carbon emission threshold of the system;

[0104] (1c) Based on the power balance, establish the power balance constraint:

[0105] C G T G +C WT T WT +C PV T PV +C SD T SD +C QY T QY +C YW T YW -E chu ≥E load +E bei (3)

[0106] In the formula, E bei is the reserve power, E chu E is the power loss of energy storage charging and discharging, chu The formula is:

[0107] E chu =(P ch -P ch η ch )T ch +(P dis / η dis -P dis )T dis (4)

[0108] Where P ch is the energy storage charging power, η ch is the energy storage charging efficiency, T ch is the annual charging time of energy storage, P dis is the energy storage discharge power, η dis is the energy storage discharge efficiency, T dis is the annual discharge duration of energy storage;

[0109] (1d) Based on the power capacity, establish power capacity constraints:

[0110] C G,max ≥C G ≥C G,min (5)

[0111] C WT,max ≥C WT ≥C WT,min (6)

[0112] C PV,max ≥C PV ≥C PV,min (7)

[0113] CSD,max ≥C SD ≥C SD,min (8)

[0114] C QY,max ≥C QY ≥C QY,min (9)

[0115] C YW,max ≥C YW ≥C YW,min (10)

[0116] P ch,max ≥P ch ≥P ch,min (11)

[0117] P dis,max ≥P dis ≥P dis,min (12)

[0118] Formula to middle, C G,max is the maximum installed capacity of thermal power, C G,min is the minimum installed capacity of thermal power, C WT,max is the maximum installed capacity of wind power, C WT,min is the minimum installed capacity of wind power, C PV,max is the maximum installed capacity of photovoltaic power generation, C PV,min is the minimum installed capacity of photovoltaic power generation, C SD,max is the maximum installed capacity of hydropower, C SD,min is the minimum installed capacity of hydropower, C QY,max is the maximum installed capacity of the remaining power sources, C QY,min is the minimum installed capacity of the remaining power sources, C YW,max is the maximum installed capacity of DC power outside the region, C YW,min is the minimum installed capacity of DC power outside the region, P ch,max is the maximum charging power of energy storage, P ch,min is the minimum charging power of energy storage, P dis,max is the maximum discharge power of energy storage, P dis,min is the minimum discharge power of energy storage;

[0119] (1e) Based on the annual power utilization hours requirements, establish annual power utilization hours constraints:

[0120]

[0121] Where, T G,min is the minimum annual utilization hours of thermal power, T WT,min is the minimum annual utilization hours of wind power, T PV,min is the minimum annual utilization hours of photovoltaic power generation, T SD,min is the minimum annual utilization hours of hydropower, TSD,max is the maximum annual utilization hours of hydropower, T QY,min is the minimum annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of other power sources, T YW,min is the minimum annual utilization hours of DC power outside the region, T YW,max T is the maximum annual utilization hours of DC power outside the region, ch,max is the maximum annual charging hours of energy storage, T ch,min is the minimum annual charging hours for energy storage, T dis,max is the maximum annual discharge hours of energy storage, T dis,min is the minimum annual discharge hours of energy storage;

[0122] Formula (1) to Formula (13) together constitute an evaluation model that takes power balance into consideration.

[0123] The step (2) specifically comprises the following steps:

[0124] (2a) Taking the maximum annual power surplus of each unit in the entire system as the goal, the objective function is established:

[0125]

[0126] Where C' G To consider the thermal power capacity to balance the peak power, ξ G is the proportion of thermal power capacity included in the peak balance, ξ WT is the proportion of wind power capacity included in the peak balance, ξ PV is the proportion of photovoltaic capacity included in the peak balance, ξ SD is the proportion of hydropower capacity included in the peak balance, ξ QY The remaining power sources are included in the peak balance ratio, ξ YW The peak balance ratio of DC outside the region, ξ ch The peak balance ratio of energy storage is P load is the maximum load in a year, N t is the number of hours in a year, N G is the number of thermal power installed units, P G,max is the maximum output of thermal power G, P G,t is the output of thermal power G at time t, P WT,t is the abandoned air volume at time t, P PV,t is the amount of abandoned light at time t, P load,t is the load size at time t, P ch is the energy storage charging power, C WT is the installed capacity of wind power, C PV is the photovoltaic installed capacity, C SD is the installed capacity of hydropower, C QY is the installed capacity of the remaining power sources, C YWIt is the DC installed capacity outside the region;

[0127] (2b) Based on the peak power balance, establish the peak power balance constraint:

[0128] C' G ξ G +C WT ξ WT +C PV ξ PV +C SD ξ SD +C QY ξ QY +C YW ξ YW +P ch ξ ch ≥P load +P bei (15)

[0129] Where P bei Provides backup power capacity for the system;

[0130] (2c) Based on the installed capacity of thermal power, establish the thermal power installed capacity constraints:

[0131] C' G,max ≥C' G ≥C' G,min (16)

[0132] Where C' G,max To consider the upper limit of thermal power capacity to balance peak power, C' G,min The lower limit of thermal power capacity to consider peak power balance;

[0133] (2d) According to the operation status of cluster units, establish output power constraints and unit climbing constraints:

[0134]

[0135]

[0136]

[0137] Where: represents the output upper limit of cluster unit g, Indicates the lower limit of the output of cluster unit g, is the ratio of the startup power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the shutdown power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the maximum upward climbing capacity of cluster unit g in unit time to the total operating capacity of the unit, is the ratio of the maximum downward ramping capacity of cluster unit g in unit time to the total operating capacity of the unit, O g,t represents the sum of the rated capacities of the online generating units of cluster unit g at time t, SU g,t-1 represents the sum of the rated capacities of the generating units that are planned to be started by cluster unit g at time t-1, SD g,t-1 represents the sum of the rated capacities of the generating units of cluster unit g that are scheduled to be shut down at time t-1, P g,t represents the sum of the rated capacities of all units in cluster unit g at time t;

[0138] (2e) Establish minimum start-stop time constraints:

[0139] 0≤SD g,1 ≤O g,0 (20)

[0140]

[0141]

[0142] 0≤SU g,1 ≤P g -O g,0 (twenty three)

[0143]

[0144]

[0145] Formula to middle: O g,0 is the online operating capacity of cluster unit g in the initial time period; UT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g; DT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g;

[0146] (2f) Establish output constraints for new energy sources:

[0147] P wr,t +P wa,t =P w,t (26)

[0148] P pr,t +P pa,t =P p,t (27)

[0149]

[0150] Where: P wr,t and P pr,tare the actual grid-connected outputs of wind power and photovoltaic power respectively; P wa,t and P pa,t are wind power and photovoltaic power abandonment respectively; P w,t and P p,t are the theoretical outputs of wind power and photovoltaic power respectively;

[0151] (2g) The energy storage operation constraints are:

[0152]

[0153] 0≤E t ≤E ESS (30)

[0154] 0≤P ch,t ≤P ESS (31)

[0155] 0≤P dis,t ≤P ESS (32)

[0156] 0≤P dis,t ≤β t M (33)

[0157] 0≤P ch,t ≤(1-β t )M (34)

[0158]

[0159]

[0160] In the formula, E t represents the capacity of energy storage at time t, η ch and η dis are the charging and discharging efficiency of energy storage, P ch,t and P dis,t are the charging and discharging power of energy storage respectively; E ESS Indicates the rated capacity of energy storage; P ESS Indicates the rated power of energy storage; β t is a variable of 0 or 1, 1 indicates that the energy storage is in a discharging state, and 0 indicates that the energy storage is in a charging state; M is a positive real number; SOC min Indicates the minimum state of charge of energy storage; SOC maxrepresents the maximum state of charge of the energy storage; formula (29) is the energy balance equation of the energy storage in adjacent time periods, formula (30) limits the real-time capacity of the energy storage to not exceed the rated capacity of the energy storage, formulas (31) and (32) limit the real-time charging and discharging power of the energy storage to not exceed the rated power of the energy storage, formulas (33) and (34) are the energy storage charging and discharging state restriction constraints, which stipulate that the energy storage can only be in the charging state or the discharging state at the same time, formula (35) is the maximum discharge capacity constraint of the energy storage, and formula (36) is the maximum charging capacity constraint of the energy storage.

[0161] Equations (14) to (36) together constitute the optimization evaluation model for thermal power installed capacity.

[0162] The step (3) specifically comprises the following steps:

[0163] (3a) According to the swing equation, the dynamic frequency response of the power system is obtained:

[0164]

[0165] Where: Δf(t) is the frequency deviation; D is the load damping coefficient; ΔP G (t) is the increase in active power output of the thermal power unit under the condition of power generation loss ΔP; H eq is the total inertia time constant of the system;

[0166] (3b) The system power generation loss ΔP is taken as input and the frequency deviation Δf is taken as output to model the system. The transfer function is:

[0167]

[0168] In the formula, K i is the mechanical power gain factor; R i F is the static adjustment coefficient of thermal power unit; i is the fraction of the total power generated by the high pressure turbine; T i is the time constant of the thermal power unit speed regulator; ΔP(t) is the power loss of the system at time t, H G is the inertia time constant of the thermal power unit, s is the complex frequency in the Laplace domain;

[0169] (3c) The time constant T of different speed regulators i With the same value T R Instead, simplify the frequency domain expression of Δf:

[0170]

[0171] Where ξ is the damping ratio, ω f is the natural vibration frequency;

[0172] (3d) Using the inverse Laplace transform and taking the derivative of the time domain expression of Δf with respect to t, let dΔf(t) / dt = 0, and we can get the lowest frequency point f nadir As shown below:

[0173]

[0174] Where f0 is the reference frequency; t nadir is the time corresponding to the lowest frequency, R T is the total power-frequency static characteristic coefficient of the generator set, F is the fraction of the total power, and the calculation formula is as follows:

[0175]

[0176] The step (4) specifically refers to: determining the lowest frequency point f of the solution in the thermal power plant assembly solution set nadir Whether it meets the requirements, if the frequency is the lowest point f nadir Within the range of [49.8,50.2] Hz, it is determined that the solution is a thermal power capacity support solution that meets the system power balance and safe and stable.

[0177] In summary, the present invention is based on system power balance, considers the installed capacity and annual maximum utilization hours of different power sources, establishes an evaluation model considering power balance, and optimizes the thermal power installed capacity that meets the system power balance constraints as a preliminary plan; based on the system power balance, the present invention considers the peak power balance and the annual time sequence power balance on the basis of the thermal power pre-installed unit plan, establishes a thermal power installed capacity optimization evaluation model, and generates a set of thermal power unit assembly plans; from the perspective of ensuring the safe and stable operation of the system, the present invention performs frequency verification on each thermal power installation plan, considers frequency support, analyzes the lowest point of the system frequency when the system is disturbed, and screens out a thermal power bottom capacity plan that meets the system power balance and safety and stability.

Claims

1. A method for evaluating the thermal power capacity supporting capacity considering power balance and stability and safety, characterized by: The method comprises the following steps in order: (1) With the goal of maximizing the annual power surplus of each unit in the entire system, an evaluation model that considers power balance is established, a preliminary evaluation of thermal power installed capacity is conducted, and a preliminary thermal power installed capacity plan is generated; (2) Based on the thermal power installed capacity pre-plan, with the goal of maximizing the annual power surplus of each unit in the entire system, an optimization evaluation model for thermal power installed capacity is established, and the thermal power installed capacity is further evaluated to generate a thermal power plan and an energy storage plan. The thermal power plan and the energy storage plan constitute a set of thermal power installed capacity plans; (3) Based on the dynamic process of power system frequency response, taking into account the frequency modulation of conventional thermal power active power, the lowest frequency point f of the system is generated nadir ; (4) Using the generated frequency minimum point f nadir The generated set of thermal power plant assembly unit solutions is screened to select the thermal power bottom capacity solution that meets the system power balance and safety and stability.

2. The thermal power capacity assessment method considering power and electricity balance and stability and safety according to claim 1 is characterized by: In step (1), the establishment of an evaluation model considering power balance specifically includes the following steps: (1a) Establish the objective function for maximizing the annual power surplus of each unit in the entire system: In the formula, C G is the installed capacity of thermal power, T G is the annual utilization hours of thermal power, T G,max is the maximum annual utilization hours of thermal power, C WT is the installed capacity of wind power, T WT is the annual utilization hours of wind power, T WT,max is the maximum annual utilization hours of wind power, C PV is the photovoltaic installed capacity, T PV is the annual utilization hours of photovoltaic power, T PV,max is the maximum annual utilization hours of photovoltaic power generation, C SD is the installed capacity of hydropower, T SD is the annual utilization hours of hydropower, T SD,max is the maximum annual utilization hours of hydropower, C QY is the installed capacity of the remaining power sources, T QY is the annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of the remaining power supply, C YW is the installed capacity of DC power outside the region, T YW is the annual utilization hours of DC power outside the region, T YW,max E is the maximum annual utilization hours of DC power outside the region, load is the load power; (1b) According to the carbon emission requirements, set carbon emission constraints for thermal power generators: x tan C G T G ≤C tan (2) In the formula, ξ tan is the carbon emission coefficient of thermal power, C tan is the annual carbon emission threshold of the system; (1c) Based on the power balance, establish the power balance constraint: C G T G +C WT T WT +C PV T PV +C SD T SD +C QY T QY +C YW T YW -E chu ≥E load +E bei (3) In the formula, E bei is the reserve power, E chu E is the power loss of energy storage charging and discharging, chu The formula is: AND chu =(P ch -P ch η ch )T ch +(P dis / η dis -P dis )T dis (4) Where P ch is the energy storage charging power, η ch is the energy storage charging efficiency, T ch is the annual charging time of energy storage, P dis is the energy storage discharge power, η dis is the energy storage discharge efficiency, T dis is the annual discharge duration of energy storage; (1d) Based on the power capacity, establish power capacity constraints: C G,max ≥C G ≥C G,min (5) C WT,max ≥C WT ≥C WT,min (6) C PV,max ≥C PV ≥C PV,min (7) C SD,max ≥C SD ≥C SD,min (8) C QY,max ≥C QY ≥C QY,min (9) C YW,max ≥C YW ≥C YW,min (10) P ch,max ≥P ch ≥P ch,min (11) P dis,max ≥P dis ≥P dis,min (12) Formula to middle, C G,max is the maximum installed capacity of thermal power, C G,min is the minimum installed capacity of thermal power, C WT,max is the maximum installed capacity of wind power, C WT,min is the minimum installed capacity of wind power, C PV,max is the maximum installed capacity of photovoltaic power generation, C PV,min is the minimum installed capacity of photovoltaic power generation, C SD,max is the maximum installed capacity of hydropower, C SD,min is the minimum installed capacity of hydropower, C QY,max is the maximum installed capacity of the remaining power sources, C QY,min is the minimum installed capacity of the remaining power sources, C YW,max is the maximum installed capacity of DC power outside the region, C YW,min is the minimum installed capacity of DC power outside the region, P ch,max is the maximum charging power of energy storage, P ch,min is the minimum charging power of energy storage, P dis,max is the maximum discharge power of energy storage, P dis,min is the minimum discharge power of energy storage; (1e) Based on the annual power utilization hours requirements, establish annual power utilization hours constraints: Where, T G,min is the minimum annual utilization hours of thermal power, T WT,min is the minimum annual utilization hours of wind power, T PV,min is the minimum annual utilization hours of photovoltaic power generation, T SD,min is the minimum annual utilization hours of hydropower, T SD,max is the maximum annual utilization hours of hydropower, T QY,min is the minimum annual utilization hours of other power sources, T QY,max is the maximum annual utilization hours of other power sources, T YW,min is the minimum annual utilization hours of DC power outside the region, T YW,max T is the maximum annual utilization hours of DC power outside the region, ch,max is the maximum annual charging hours of energy storage, T ch,min is the minimum annual charging hours for energy storage, T dis,max is the maximum annual discharge hours of energy storage, T dis,min is the minimum annual discharge hours of energy storage; Formula (1) to Formula (13) together constitute an evaluation model that takes power balance into consideration.

3. The thermal power capacity assessment method considering power and electricity balance and stability and safety according to claim 1 is characterized by: In step (2), the establishment of the thermal power installed capacity optimization evaluation model specifically includes the following steps: (2a) Taking the maximum annual power surplus of each unit in the entire system as the goal, the objective function is established: Where C' G To consider the thermal power capacity to balance the peak power, ξ G is the proportion of thermal power capacity included in the peak balance, ξ WT is the proportion of wind power capacity included in the peak balance, ξ PV is the proportion of photovoltaic capacity included in the peak balance, ξ SD is the proportion of hydropower capacity included in the peak balance, ξ QY The remaining power sources are included in the peak balance ratio, ξ YW The peak balance ratio of DC outside the region, ξ ch is the peak balance ratio of energy storage, P load is the maximum load in a year, N t is the number of hours in a year, N G is the number of thermal power installed units, P G,max is the maximum output of thermal power G, P G,t is the output of thermal power G at time t, P WT,t is the abandoned air volume at time t, P PV,t is the amount of abandoned light at time t, P load,t is the load size at time t, P ch is the energy storage charging power, C WT is the installed capacity of wind power, C PV is the photovoltaic installed capacity, C SD is the installed capacity of hydropower, C QY is the installed capacity of the remaining power sources, C YW It is the DC installed capacity outside the region; (2b) Based on the peak power balance, establish the peak power balance constraint: C' G x G +C WT x WT +C PV x PV +C SD x SD +C QY x QY +C YW x YW +P ch x ch ≥P load +P bei (15) Where P bei Provides backup power capacity for the system; (2c) Based on the installed capacity of thermal power, establish the thermal power installed capacity constraints: C' G,max ≥C' G ≥C' G,min (16) Where C' G,max To consider the upper limit of thermal power capacity to balance peak power, C' G,min The lower limit of thermal power capacity to consider peak power balance; (2d) According to the operation status of cluster units, establish output power constraints and unit climbing constraints: Where: represents the output upper limit of cluster unit g, Indicates the lower limit of the output of cluster unit g, is the ratio of the startup power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the shutdown power variation capability of cluster unit g to the total operating capacity of the units; is the ratio of the maximum upward climbing capacity of cluster unit g in unit time to the total operating capacity of the unit, is the ratio of the maximum downward ramping capacity of cluster unit g in unit time to the total operating capacity of the unit, O g,t represents the sum of the rated capacities of the online generating units of cluster unit g at time t, SU g,t-1 represents the sum of the rated capacities of the generating units that are planned to be started by cluster unit g at time t-1, SD g,t-1 represents the sum of the rated capacities of the generating units of cluster unit g that are scheduled to be shut down at time t-1, P g,t represents the sum of the rated capacities of all units in cluster unit g at time t; (2e) Establish minimum start-stop time constraints: 0≤SD g,1 ≤O g,0 (20) 0≤SU g,1 ≤P g -THE g,0 (23) Formula to middle: O g,0 is the online operating capacity of cluster unit g in the initial time period; UT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g; DT g is the minimum startup time of cluster unit g, and is the average value of the minimum startup time of all units in cluster unit g; (2f) Establish output constraints for new energy sources: P wr,t +P wa,t =P w,t (26) P pr,t +P pa,t =P p,t (27) Where: P wr,t and P pr,t are the actual grid-connected outputs of wind power and photovoltaic power respectively; P wa,t and P pa,t are wind power and photovoltaic power abandonment respectively; P w,t and P p,t are the theoretical outputs of wind power and photovoltaic power respectively; (2g) The energy storage operation constraints are: 0≤E t ≤E ESS (30) 0≤P ch,t ≤P ESS (31) 0≤P dis,t ≤P ESS (32) 0≤P dis,t ≤β t M (33) 0≤P ch,t ≤(1-β t )M (34) In the formula, E t represents the capacity of energy storage at time t, η ch and η dis are the charging and discharging efficiency of energy storage, P ch,t and P dis,t are the charging and discharging power of energy storage respectively; E ESS Indicates the rated capacity of energy storage; P ESS Indicates the rated power of energy storage; β t is a variable of 0 or 1, 1 indicates that the energy storage is in a discharging state, and 0 indicates that the energy storage is in a charging state; M is a positive real number; SOC min Indicates the minimum state of charge of energy storage; SOC max Indicates the maximum state of charge of the energy storage; Equations (14) to (36) together constitute the optimization evaluation model for thermal power installed capacity.

4. The thermal power capacity assessment method considering power balance and stability and safety according to claim 1 is characterized by: The step (3) specifically comprises the following steps: (3a) According to the swing equation, the dynamic frequency response of the power system is obtained: Where: Δf(t) is the frequency deviation; D is the load damping coefficient; ΔP G (t) is the increase in active power output of the thermal power unit under the condition of power generation loss ΔP; H eq is the total inertia time constant of the system; (3b) The system power generation loss ΔP is taken as input and the frequency deviation Δf is taken as output to model the system. The transfer function is: In the formula, K i is the mechanical power gain factor; R i F is the static adjustment coefficient of thermal power unit; i is the fraction of the total power generated by the high pressure turbine; T i is the time constant of the thermal power unit speed regulator; ΔP(t) is the power loss of the system at time t, H G is the inertia time constant of the thermal power unit, s is the complex frequency in the Laplace domain; (3c) The time constant T of different speed regulators i With the same value T R Instead, simplify the frequency domain expression of Δf: Where ξ is the damping ratio, ω f is the natural vibration frequency; (3d) Using the inverse Laplace transform and taking the derivative of the time domain expression of Δf with respect to t, let dΔf(t) / dt = 0, and we can get the lowest frequency point f nadir As shown below: Where f0 is the reference frequency; t nadir is the time corresponding to the lowest frequency, R T is the total power-frequency static characteristic coefficient of the generator set, F is the fraction of the total power, and the calculation formula is as follows:

5. The thermal power capacity assessment method considering power and electricity balance and stability and safety according to claim 1 is characterized by: The step (4) specifically refers to: determining the lowest frequency point f of the solution in the thermal power plant assembly solution set nadir Whether it meets the requirements, if the frequency is the lowest point f nadir Within the range of [49.8,50.2] Hz, it is determined that the solution is a thermal power capacity support solution that meets the system power balance and safe and stable.

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