A frequency stability constraint solution method for a given new energy grid-connected scene

Abstract

The present application provides a kind of frequency stability constraint solution method for given new energy grid-connected scene, including the following methods: step S1: obtain the maximum disturbance constraint primary frequency modulation capacity limit based on frequency stability;Step S2: given regional power grid minimum standby demand capacity and ≤, then turn to step S4;Otherwise, turn to step S3;Step S3: after increasing the installed capacity of primary frequency modulation power supply, turn to step S1;Step S4: obtain the active power of thermal power unit that meets the minimum frequency constraint;Step S5: obtain the actual active output of thermal power unit;Step S6: if, turn to step S7;Otherwise, turn to step S8;Step S7: if start-up can carry set new energy index, then the process is ended;Step S8: if it is necessary to increase the energy storage hot standby capacity on the basis of the actual output of thermal power unit obtained according to the power generation load balance constraint, then the process is ended;The present application can form the coping strategy considering conventional machine and multiple categories of power supply such as energy storage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, in particular to a frequency stability constraint solving method for a given new energy grid-connected scenario. BACKGROUND

[0002] Under the background of the rising of new power systems, with the rapid growth of new energy grid-connected installed capacity and total consumption, the contradiction of consumption is increasingly prominent, and the influence on the safe and stable operation of the power system cannot be ignored. When new energy generators are connected to the grid, they will replace the original synchronous generators in the grid, reducing the rotational inertia of the power system and severely reducing the frequency regulation capability of the grid.

[0003] With the improvement of new energy consumption indicators, the way of reducing conventional power output or shutting down conventional power start-up cannot fully represent the frequency constraint stable operation domain of the power system under the scenario of direct current multi-feed and high penetration of new energy. Therefore, the frequency stability constraint solving method for a given new energy grid-connected scenario has become a research hotspot. SUMMARY

[0004] The present application proposes a frequency stability constraint solving method for a given new energy grid-connected scenario, which clearly defines the participating factors to be considered, such as load frequency effect, control measure quantity, demand side response, and primary frequency variation range of each type of unit, etc. By analyzing the load data of the research regional power grid, a coping strategy considering multiple types of power sources such as conventional machines and energy storage is proposed under the given new energy grid-connected scenario.

[0005] The present application adopts the following technical solutions.

[0006] A frequency stability constraint solving method for a given new energy grid-connected scenario, by analyzing the load data of the research regional power grid, a coping strategy considering multiple types of power sources such as conventional machines and energy storage is proposed under the given new energy grid-connected scenario, including the following methods:

[0007] Step S1: Under the boundary condition of the research regional power grid, the maximum disturbance constraint primary frequency capacity limit P limit is obtained based on frequency stability.

[0008] Step S2: Compare the given regional power grid minimum standby demand capacity with the maximum disturbance constraint primary frequency capacity limit P i , if P limit , go to step S4; otherwise, go to step S3;

[0009] Step S3: After increasing the primary frequency power installed capacity, go to step S1;

[0010] Step S4: Under the boundary conditions of the power grid in the study area, obtain the active power P of the thermal power unit that satisfies the minimum frequency constraint. f-fire ;

[0011] Step S5: Under the boundary conditions of the power grid in the study area, obtain the actual active power output P of the thermal power unit from the power generation load balance constraint condition. fire ;

[0012] Step S6: Calculate the actual output P of the thermal power unit obtained in Step S5 based on the power generation load balance constraint. fire Step S4 is based on the active power P of the thermal power unit that meets the minimum frequency constraint. f-fire For comparison, if ΔP = P fire -P f-fire >0, proceed to step S7; otherwise, proceed to step S8;

[0013] Step S7: If the existing power supply can support the set new energy indicators, the process ends;

[0014] Step S8: If it is necessary to calculate the actual output P of the thermal power unit based on the power generation load balance constraint... fire Based on the initial startup, increase the energy storage hot standby capacity α. fire If *|ΔP| is reached, the process ends.

[0015] The specific method for step S1 is as follows:

[0016] The primary frequency modulation capacity limit under the maximum disturbance constraint is expressed by the formula:

[0017] P limit =P load-f +(α fire *P ins-fire +α water *P ins-water +α ps *P ins-ps +α es *P ins-es )+P con +P response Formula 1;

[0018] In the formula: P limit P represents the maximum disturbance in the power grid of the studied region that satisfies the frequency stability constraint under this boundary condition. load-f The load change corresponding to the system frequency dropping from 50Hz to 49Hz is affected by the frequency characteristics of the system load and is expressed by the formula:

[0019] P load-f =ε*P L Formula 2;

[0020] ε is the load frequency response factor of the regional power grid under the boundary condition; P ins-fire P is the thermal power installed capacity of the regional power grid under the boundary condition; P ins-water P is the hydropower installed capacity of the regional power grid under the boundary condition; P ins-ps P is the pumped storage installed capacity of the regional power grid under the boundary condition; P ins-es P is the energy storage installed capacity of the regional power grid under the boundary condition; α fire α is the primary frequency modulation proportion of the thermal power unit of the regional power grid; α water α is the primary frequency modulation proportion of the hydropower unit of the regional power grid; α ps α is the primary frequency modulation proportion of the pumped storage unit of the regional power grid; α es α is the primary frequency modulation proportion of the energy storage unit of the regional power grid; α windg α is the primary frequency modulation proportion of the wind power unit of the regional power grid; α pv α is the primary frequency modulation proportion of the photovoltaic unit of the regional power grid; P con P is the serious fault control quantity of the regional power grid under the boundary condition; P response P is the serious fault demand side response quantity of the regional power grid under the boundary condition:

[0021] P response = η * P L Equation three;

[0022] η is the demand side response factor of the regional power grid under the boundary condition.

[0023] The specific method of step S3 is:

[0024] Change the thermal power installed capacity P ins-fire , and then go back to step S1 to execute, and meet the minimum active capacity of the standby demand P i by increasing the primary frequency modulation power supply:

[0025] P i = P loss = P load-f + P r + P con + P response Equation four;

[0026] In the formula:

[0027] P i is the minimum active capacity of the standby demand of the regional power grid under the boundary condition to meet the frequency stability constraint; P loss P is the active deficiency quantity caused by disturbance of the regional power grid under the boundary condition; P rThe sum of the primary frequency regulation quantities that can be adjusted by various generating units under the boundary conditions of severe fault power deficit in the power grid of the studied area:

[0028] P r =P r-fire +P r-water +P r-ns +P r-es +P r-windg +P r-pv Formula 5;

[0029] P r-fire The primary frequency regulation that can be adjusted by thermal power units with power deficit due to severe faults under the boundary conditions of the power grid in the studied area is:

[0030] P r-fire =α fire *P fire Formula Six;

[0031] Among them, P fire The active power output of thermal power plants under this boundary condition in the power grid of the studied area;

[0032] P r-water The primary frequency regulation that can be adjusted by hydropower units under severe fault power deficit conditions in the power grid of the studied area is:

[0033] P r-water =α water *P water Formula 7;

[0034] Among them, P water The active power output of hydropower in the power grid of the studied region under this boundary condition;

[0035] P r-ps The primary frequency regulation that can be adjusted by pumped-storage units under the boundary conditions of severe fault power deficit in the power grid of the studied area is:

[0036] P r-ps =α ps *P ps Formula 8;

[0037] Among them, P ps The active power output of pumped storage under this boundary condition of the power grid in the studied area;

[0038] P r-es The primary frequency regulation that the energy storage unit can adjust to compensate for the power deficit due to a severe fault in the power grid of the studied area under this boundary condition is:

[0039] P r-es =α es *P es Formula Nine;

[0040] Among them, P es The active power output of energy storage in the power grid of the studied area under this boundary condition;

[0041] P r-windg The primary frequency regulation that can be adjusted by wind turbines under severe fault power deficit conditions in the power grid of the studied area is:

[0042] P r-windg =α windg *P g-windg Formula 10;

[0043] Among them, P g-windg The active power output of the wind power index under this boundary condition for the power grid in the studied area;

[0044] P r-pv This represents the primary frequency regulation that photovoltaic units can adjust to compensate for power deficit due to severe faults in the power grid of the studied region under this boundary condition.

[0045] P r-pv =α pv *P g-pv Formula 11;

[0046] Among them, P g-pv The active power output of the photovoltaic index under the boundary conditions of the power grid in the studied area.

[0047] In step S4, the actual power output of thermal power plants that satisfy the minimum frequency constraint is expressed by the formula:

[0048]

[0049] In the formula: P f-fire This refers to the active power of the power grid in the studied area that satisfies the minimum frequency constraint under this boundary condition.

[0050] In step S5, the method for calculating the actual active power output of the thermal power unit is expressed by the following formula:

[0051] P L +P S =P N +P T +P G Formula Thirteen;

[0052] P fire =(P L +P S -P N -P T )-(P water +P ps +P es +P g-new Formula Fourteen;

[0053] In the formula, P L P is the total load of the regional power grid under study; P S P is the total loss of the regional power grid under study under the total load; P N P is the DC external power of the regional power grid under study under the boundary condition; P T P is the AC external power of the regional power grid under study under the boundary condition; P G P is the AC power source of the regional power grid under study under the boundary condition:

[0054] P G = P fire + P water + P ps + P es + P g-new Formula fifteen;

[0055] P g-new is the new energy index active power under the boundary condition of the regional power grid under study:

[0056] P g-new = P g-windg + P g-pv Formula sixteen.

[0057] In step S6, ΔP is the active power difference under the boundary condition of the regional power grid under study to meet the power generation load balance and meet the minimum frequency constraint.

[0058] The present application clearly defines the participating factors that need to be considered, such as load frequency effect, control measure quantity, demand side response and primary frequency modulation range of various types of units, can analyze the load data of the regional power grid, and propose a response strategy considering multiple types of power sources such as conventional machines and energy storage under the given new energy grid connection scenario; can propose a solution method based on frequency stability constraint according to the installed capacity of each type of power source of the regional power grid under study and the set primary frequency modulation range under the given new energy grid connection scenario, so as to determine the output ratio and hot standby capacity of each type of power source. BRIEF DESCRIPTION OF DRAWINGS

[0059] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0060] Figure 1 is a flowchart of the method of the present application; Figure 1 Figure 2 is a schematic diagram of the frequency change of the ultra-high voltage bus under the condition of 2# DC 8 million bipolar blocking + 1 million single machine fault in the embodiment.

[0061] DETAILED DESCRIPTION Figure 2

[0062] ​​As shown in the figure, a solution to the frequency stability constraints under a given renewable energy grid connection scenario is proposed. By analyzing the load data of the regional power grid, a strategy considering multiple power sources such as conventional generators and energy storage is put forward under the given renewable energy grid connection scenario, including the following methods:

[0063] Step S1: Under the boundary conditions of the power grid in the study area, obtain the primary frequency regulation capacity limit P based on the maximum disturbance constraint for frequency stability. limit ;

[0064] Step S2: Compare the given minimum positive reserve demand capacity of the regional power grid with the primary frequency regulation capacity limit under the maximum disturbance constraint. If P i ≤P limit If yes, proceed to step S4; otherwise, proceed to step S3.

[0065] Step S3: After installing the frequency modulation power supply, proceed to step S1;

[0066] Step S4: Under the boundary conditions of the power grid in the study area, obtain the active power P of the thermal power unit that satisfies the minimum frequency constraint. f-fire ;

[0067] Step S5: Under the boundary conditions of the power grid in the study area, obtain the actual active power output P of the thermal power unit from the power generation load balance constraint condition. fire ;

[0068] Step S6: Calculate the actual output P of the thermal power unit obtained in Step S5 based on the power generation load balance constraint. fire Step S4 is based on the active power P of the thermal power unit that meets the minimum frequency constraint. f-fire For comparison, if ΔP = P fire -P f-fire >0, proceed to step S7; otherwise, proceed to step S8;

[0069] Step S7: If the existing power supply can support the set new energy indicators, the process ends;

[0070] Step S8: If it is necessary to calculate the actual output P of the thermal power unit based on the power generation load balance constraint... fire Based on the initial startup, increase the energy storage hot standby capacity α. fire If *|ΔP| is reached, the process ends.

[0071] The specific method for step S1 is as follows:

[0072] The primary frequency modulation capacity limit under the maximum disturbance constraint is expressed by the formula:

[0073] P limit =P load-f +(α fire *P ins-fire+α water *P ins-water +α ps *P ins-ps +α es *P ins-es )+P con +P response Formula 1;

[0074] In the formula: P limit This represents the maximum disturbance in the power grid of the studied region that satisfies the frequency stability constraint under this boundary condition.

[0075] P load-f The load change corresponding to the system frequency dropping from 50Hz to 49Hz is affected by the frequency characteristics of the system load and is expressed by the formula:

[0076] P load-f =ε*P L Formula 2;

[0077] ε is the load frequency response factor of the power grid in the studied area under this boundary condition; P ins-fire P represents the thermal power capacity of the power grid in the studied region under these boundary conditions. ins-water P represents the hydropower installed capacity of the power grid in the studied area under these boundary conditions. ins-ps P represents the pumped storage capacity of the power grid in the studied area under these boundary conditions. ins-es α represents the installed capacity of energy storage in the power grid of the studied region under this boundary condition; fire α represents the primary frequency regulation ratio of the thermal power units in the power grid of the studied region. water α represents the primary frequency regulation ratio of the hydropower units in the power grid of the studied region. ps α represents the primary frequency regulation ratio of the pumped-storage units in the power grid under study; es α represents the primary frequency regulation ratio of the energy storage units in the power grid of the studied area; windg α represents the primary frequency regulation ratio of the wind turbine generators in the power grid of the studied area. pv P represents the primary frequency regulation ratio of the photovoltaic units in the power grid of the studied area. con P represents the safety control quantity for severe faults in the power grid of the studied area under this boundary condition; response For the demand-side response of the power grid in the studied area under this boundary condition of severe fault:

[0078] P response =η*P L Formula 3;

[0079] η is the demand-side response factor of the power grid in the studied area under this boundary condition.

[0080] The specific method for step S3 is as follows:

[0081] P ins-fire After that, go back to step S1 to execute, by increasing the primary frequency modulation power to meet the minimum active capacity P i :

[0082] P i = P loss = P load-f + P r + P con + P response Equation four;

[0083] Wherein:

[0084] P i is the minimum active capacity of the power grid in the study area under the boundary condition to meet the frequency stability constraint; P loss is the active power shortage caused by disturbance in the power grid in the study area under the boundary condition; P r is the primary frequency modulation amount of various types of units that can be adjusted due to serious fault power shortage in the power grid in the study area under the boundary condition, and:

[0085] P r = P r-fire + P r-water + P r-ps + P r-es + P r-windg + P r-pv Equation five;

[0086] P r-fire is the primary frequency modulation amount of thermal power units that can be adjusted due to serious fault power shortage in the power grid in the study area under the boundary condition:

[0087] P r-fire = α fire * P fire Equation six;

[0088] Wherein, P fire is the thermal power active output of the power grid in the study area under the boundary condition;

[0089] P r-water is the primary frequency modulation amount of hydroelectric units that can be adjusted due to serious fault power shortage in the power grid in the study area under the boundary condition:

[0090] P r-water = α water * P water Equation seven;

[0091] Wherein, P water is the hydroelectric active output of the power grid in the study area under the boundary condition;

[0092] P r-psThe primary frequency regulation that can be adjusted by pumped-storage units under the boundary conditions of severe fault power deficit in the power grid of the studied area is:

[0093] P r-ps =α ps *P ps Formula 8;

[0094] Among them, P ps The active power output of pumped storage under this boundary condition of the power grid in the studied area;

[0095] P r-es The primary frequency regulation that the energy storage unit can adjust to compensate for the power deficit due to a severe fault in the power grid of the studied area under this boundary condition is:

[0096] P r-es =α es *P es Formula Nine;

[0097] Among them, P es The active power output of energy storage in the power grid of the studied area under this boundary condition;

[0098] p r-windg The primary frequency regulation that can be adjusted by wind turbines under severe fault power deficit conditions in the power grid of the studied area is:

[0099] P r-windg =α windg *P g-windg Formula 10;

[0100] Among them, P g-windg The active power output of the wind power index under this boundary condition for the power grid in the studied area;

[0101] P r-pv This represents the primary frequency regulation that photovoltaic units can adjust to compensate for power deficit due to severe faults in the power grid of the studied region under this boundary condition.

[0102] P r-pv =α pv *P g-pv Formula 11;

[0103] Among them, P g-pv The active power output of the photovoltaic index under the boundary conditions of the power grid in the studied area.

[0104] In step S4, the actual power output of thermal power plants that satisfy the minimum frequency constraint is expressed by the formula:

[0105]

[0106] In the formula: P f-fire This refers to the active power of the power grid in the studied area that satisfies the minimum frequency constraint under this boundary condition.

[0107] In step S5, the method for obtaining the actual active power output of the thermal power unit is expressed in a formula as follows:

[0108] P L +P S =P N +P T +P G Equation XIII;

[0109] P fire =(P L +P S -P N -P T )-(P water +P ps +P es +P g-new ) Equation XIV;

[0110] In the formula, P L is the total load of the regional power grid under study; P S is the total network loss under the total load of the regional power grid under study; P N is the direct current external power under the boundary condition of the regional power grid under study; P T is the alternating current external power under the boundary condition of the regional power grid under study; and P G is the alternating current power source under the boundary condition of the regional power grid under study.

[0111] P G =P fire +P water +P ps +P es +P g-new Equation XV;

[0112] In the formula, P g-new is the new energy index active power under the boundary condition of the regional power grid under study.

[0113] P g-new =P g-windg +P g-pv Equation XVI.

[0114] In step S6, ΔP is the active power difference under the boundary condition of the regional power grid under study, which meets the power generation load balance and meets the minimum frequency constraint.

[0115] Embodiment:

[0116] This embodiment takes the A power grid in the 2025 level year as the research object. Through the above method, two constraints of power balance and frequency stability are set as consideration factors, and a response strategy is given for a given new energy grid connection scenario, thereby determining the output ratio and hot standby capacity of each type of power source.

[0117] Tables 1 and 2 list the power load balance of Power Grid A at a certain moment in the 2025 level year. From these tables, we can know the basic parameters such as the total load required for the example, the external power receiving capacity, and the installed capacity of each power source.

[0118] Table 1 Load situation of provinces in a certain region

[0119]

[0120] Table 2 Power Supply Configuration of Provinces in a Certain Region

[0121]

[0122]

[0123] Before the analysis, it is necessary to pre-set the load frequency factor, severe fault control quantity, demand-side response ratio, and primary frequency regulation ratio of each type of generating unit in the power grid of the study area.

[0124] According to relevant data, power grids A and D have 50% constant impedance and 50% motors, while power grids C and B have 35% constant impedance and 65% motors. In 2025, for power grid A, this embodiment considers the most stringent conditions, setting the unit load regulation power to 0%, and also disregarding demand-side response.

[0125] In the event of a severe fault, the difference in power deficit due to variations in grid size needs to be considered, and safety control devices are typically configured for severe faults. In 2025, for grid A, under the most stringent conditions, the safety control quantity is set to 0.

[0126] The frequency safety constraint for a certain regional power grid is that under severe power deficit faults, the system frequency should not fall below the first-round setting of low-frequency load shedding, meaning the system frequency should be greater than or equal to 49.25 Hz. (2025)

[0127] For Power Grid A, under the most stringent conditions, new energy generating units have no frequency regulation capability. The frequency regulation capability of conventional thermal power units is considered at 3% of the actual generator output. The frequency regulation capability of existing hydropower and pumped storage units is considered at 10% of the actual generator output. The frequency regulation capability of newly added energy storage units is considered at 100% of the actual generator output. The minimum technical output ratio of thermal power units is considered at 50%, which can be adjusted according to actual conditions.

[0128] After setting the above parameters, take the minimum positive reserve configuration of Province A (the minimum positive reserve of a certain region is 9 million kilowatts, and the part shared by Province A is 3.1473 million kilowatts) as the maximum disturbance. Taking the second working condition in Table 3 as an example, the conventional machine response strategy for the given new energy grid connection scenario under the second working condition is obtained.

[0129] The steps are as follows:

[0130] Step 1: Under the boundary conditions of the power grid in Province A, obtain the primary frequency regulation capacity limit under the maximum disturbance constraint:

[0131] P limit =α fire *P ins-fire +α water *P ins-water +α ps *P ins-ps

[0132] =3%*6642+10%*110+10%*252=235.46 (10,000 kilowatts) (1)

[0133] Step 2: Compare the given minimum positive reserve active power capacity of the A province power grid with the primary frequency regulation capacity limit under the maximum disturbance constraint, because P i >P limit Proceed to step 3;

[0134] Step 3: Do not change the thermal power plant capacity P here. ins-fire Instead, it meets the minimum positive reserve requirement P by increasing energy storage power sources. i The additional energy storage is P i -P limit = 79.27 (megawatts). After iterations in steps 1 and 2, P′ after adding energy storage limit =P i Therefore

[0135] P i (P limit ) = P loss =P r =314.73 (10,000 kilowatts) (2)

[0136]

[0137]

[0138]

[0139] Satisfying constraint P in step 2 i ≤P′ limit Proceed to step 4;

[0140] Step 4: Obtain the active power of the thermal power unit satisfying the minimum frequency constraint under the boundary condition of the A province power grid; assume P fire unknown, the actual output of the thermal power satisfying the minimum frequency constraint is: (4)

[0142] Step 5: Under the boundary condition of the A province power grid, ignore the network loss (P S = 0), and the AC external power receiving P T is 6.64 million kilowatts. Obtain the actual active power output of the thermal power unit from the power generation load balance constraint condition:

[0143] P G = P L - P N - P T = 9200-1711-664 = 6825 (million kilowatts) (5)

[0144] P fire = P G - (P water + P ps + P es + P g-new )

[0145] = 6825- (110+252+0+1492) = 4971 (million kilowatts) (6)

[0146] Step 6: Compare the actual output P fire of the thermal power unit obtained from the power generation load balance constraint in step 5 with the active power P f-fire of the thermal power unit satisfying the minimum frequency constraint in step 4. Since ΔP = P fire - P f-fire = 4971-6642 = -1671 < 0, the existing units cannot carry the set new energy target, and proceed to step 8;

[0147] Step 8: On the basis of the actual output P fire of the thermal power unit obtained from the power generation load balance constraint, increase the energy storage:

[0148] α fire * |ΔP| = 3% * 1671 = 50.13 (million kilowatts) (7)

[0149] In summary, the twice increased energy storage is 79.27+50.13 = 129.4 (million kilowatts), and the process is ended.

[0150] According to the method of the above process, the coping strategies under the given new energy grid connection scenario under different working conditions of the A power grid in 2025 are obtained as shown in Table 3.

[0151] Table 3: Conventional machine coping strategies under different working conditions for the given new energy grid-connected scenario

[0152] (unit: ten thousand kilowatts)

[0153]

[0154] Note: According to Table 1, the maximum load in A Province in the summer evening peak in 2025 is 92 million kilowatts, the installed capacity of wind power is 18.65 million kilowatts, the installed capacity of photovoltaic power is 6 million kilowatts, the installed capacity of thermal power (coal power, gas power) is about 66.42 million kilowatts, the actual output of hydropower is 1.1 million kilowatts, and the actual output of pumped storage is 2.52 million kilowatts.

[0155] Working condition one: considering the afternoon mode, the load is 85% of the evening peak, the wind power output is 10% of the installed capacity of wind power, the photovoltaic output is 100% of the installed capacity of photovoltaic power, the actual output of water and pumped storage remains unchanged, and the thermal power output is the quantity to be solved, as shown in the above table.

[0156] Working condition two: considering the evening peak mode, the load is 100% of the evening peak, the wind power output is 80% of the installed capacity of wind power, the photovoltaic output is 0% of the installed capacity of photovoltaic power, the actual output of water and pumped storage remains unchanged, and the thermal power output is the quantity to be solved, as shown in the above table.

[0157] Working condition three: considering the small mode, the load is 65% of the evening peak, the wind power output is 100% of the installed capacity of wind power, the photovoltaic output is 0% of the installed capacity of photovoltaic power, the actual output of water and pumped storage remains unchanged, and the thermal power output is the quantity to be solved, as shown in the above table.

[0158] According to the working condition two adjustment data, set the disturbance form of 800 million bipolar blocking of No. 2 DC + 1 million single machine fault, and the frequency recovery characteristic analysis calculation results of the ultra-high voltage bus are shown in Table 4 and Figure 2 .

[0159] Table 4: Frequency change of 1000kV typical bus in A, B, C and D provinces under the condition of 800 million bipolar blocking of No. 2 DC + 1 million single machine fault

[0160]

[0161] As shown in Table 4 and the accompanying drawings, the initial frequency of the 1000kV typical bus in A, B, C and D provinces is 50Hz. After setting the disturbance form of 800 million bipolar blocking of No. 2 DC + 1 million single machine fault in this region, the maximum frequency drop value of the 1000kV typical bus in A, B, C and D provinces is less than 0.2Hz, and the steady-state frequency can be stabilized at 49.92Hz, thereby verifying the correctness and effectiveness of the conventional machine coping strategies under the given new energy grid-connected scenario.

Claims

1. A solution to frequency stability constraints under a given renewable energy grid connection scenario, which, through analysis of regional power grid load data, proposes a multi-type power supply strategy considering conventional generators and energy storage under a given renewable energy grid connection scenario, characterized by: Including the following methods: Step S1: Under the boundary conditions of the power grid in the study area, obtain the maximum disturbance P that satisfies the frequency stability constraint under the boundary conditions of the power grid in the study area. limit ; Step S2: Compare the given minimum positive reserve demand capacity of the regional power grid with the primary frequency regulation capacity limit under the maximum disturbance constraint. If P i ≤P limit If yes, proceed to step S4; otherwise, proceed to step S3. P i The minimum positive reserve active capacity that satisfies frequency stability constraints under the boundary conditions of the power grid in the studied area; Step S3: After installing the frequency modulation power supply, proceed to step S1; Step S4: Under the boundary conditions of the power grid in the study area, obtain the active power P of the thermal power unit that satisfies the minimum frequency constraint under the boundary conditions of the power grid in the study area. f-fire ; Step S5: Under the boundary conditions of the power grid in the study area, obtain the actual active power output P of the thermal power unit from the power generation load balance constraint condition. fire ; Step S6: Calculate the active power output P of thermal power plants under the power grid boundary conditions of the studied area, obtained in Step S5 based on the power generation load balance constraints. fire Step S4 is based on the active power P of the thermal power unit that meets the minimum frequency constraint. f-fire For comparison, if ΔP = P fire -P f-fire >0, proceed to step S7; otherwise, proceed to step S8; Step S7: If the existing power supply can support the set new energy indicators, the process ends; Step S8: If it is necessary to calculate the actual output P of the thermal power unit based on the power generation load balance constraint... fire Based on the initial startup, additional energy storage and hot standby capacity is added, calculated using the formula α. fire *|ΔP|,α fire If the primary frequency regulation ratio of the thermal power units in the power grid of the studied area is determined, then the process ends; the specific method of step S1 is as follows: The primary frequency modulation capacity limit under the maximum disturbance constraint is expressed by the formula: P limit =P load-f +(α fire *P ins-fire +α water *P ins-water +α ps *P ins-ps +α es *P ins-es ) +P con +P response Formula 1; In the formula: P limit P represents the maximum disturbance that satisfies the frequency stability constraint under the boundary conditions of the power grid in the studied area. load-f The load change corresponding to the system frequency dropping from 50Hz to 49Hz is affected by the frequency characteristics of the system load and is expressed by the formula: P load-f =ε*P L Formula 2; P L The total load of the power grid in the studied area; ε is the load frequency response factor under the boundary conditions of the power grid in the studied area; P ins-fire P represents the installed capacity of thermal power plants under the boundary conditions of the power grid in the studied area. ins-water P represents the hydropower installed capacity under the boundary conditions of the power grid in the studied area. ins-ps P represents the pumped storage capacity under the boundary conditions of the power grid in the studied area. ins-es α represents the installed capacity of energy storage under the boundary conditions of the power grid in the studied area. fire α represents the primary frequency regulation ratio of the thermal power units in the power grid of the studied region. ps α represents the primary frequency regulation ratio of the pumped-storage units in the power grid under study; es P represents the primary frequency regulation ratio of the energy storage units in the power grid of the studied area; con P represents the safety control quantity for severe faults under the boundary conditions of the power grid in the studied area; response For the demand-side response of a severe fault under the boundary conditions of the power grid in the studied area: P response = η * P L Formula 3; η is the demand-side response factor under the boundary conditions of the power grid in the studied area.

2. The frequency stability constraint solution for a given new energy grid connection scenario as described in claim 1, characterized in that: The specific method for step S3 is as follows: Changing the thermal power installed capacity P under the boundary conditions of the power grid in the studied area ins-fire Then, proceed to step S1 to execute, where a frequency-modulated power supply is added to meet the minimum positive reserve active capacity P. i : P i =P loss =P load-f +P r +P con +P response Formula 4; In the formula: P i P represents the minimum positive reserve active power capacity required to satisfy frequency stability constraints under the boundary conditions of the power grid in the studied area. loss P represents the active power deficit caused by disturbances under the boundary conditions of the power grid in the studied area. r The sum of the primary frequency regulation quantities that can be adjusted by various generating units under the power deficit due to severe faults in the power grid boundary conditions of the studied area: P r =P r-fire +P r-water +P r-ps +P r-es +P r-windg +P r-pv Formula 5; P r-fire The primary frequency regulation that can be adjusted by thermal power units with power deficit due to severe faults under the boundary conditions of the power grid in the studied area is: P r-fire =α fire *P fire Formula Six; Among them, P fire The active power output of thermal power plants under the boundary conditions of the power grid in the studied area; P r-water The primary frequency regulation that can be adjusted by hydropower units with power deficit due to severe faults under the boundary conditions of the power grid in the studied area is: P r-water =α water *P water Formula 7; Among them, P water The active power output of hydropower under the boundary conditions of the power grid in the studied area; P r-ps The primary frequency regulation that can be adjusted by pumped-storage units under severe fault power deficit conditions at the power grid boundary of the studied area is: P r-ps =α ps *P ps Formula 8; Among them, P ps The active power output of pumped storage under the boundary conditions of the power grid in the studied area; P r-es The primary frequency regulation that can be adjusted by the energy storage unit under the power deficit due to a severe fault in the power grid boundary conditions of the studied area is: P r-es =α es *P es Formula Nine; Among them, P es The active power output of energy storage under the boundary conditions of the power grid in the studied area; P r-windg The primary frequency regulation that can be adjusted by wind turbines under severe fault power deficit conditions at the power grid boundary of the studied area is: P r-windg =α windg *P g-windg Formula 10; Among them, P g-windg The active power output of wind power under the boundary conditions of the power grid in the studied area; α windg The primary frequency regulation ratio of the wind turbine units in the power grid of the studied area; P r-pv This refers to the primary frequency regulation that can be adjusted out by photovoltaic units with power deficit due to severe faults under the boundary conditions of the power grid in the studied area. P r-pv =α pv *P g-pv Formula 11; Among them, P g-pv The photovoltaic active power output under the boundary conditions of the power grid in the studied area; α pv This represents the primary frequency regulation ratio of the photovoltaic units in the power grid of the studied area.

3. The frequency stability constraint solution for a given new energy grid connection scenario according to claim 2, characterized in that: In step S4, the actual output of thermal power plants that satisfy the minimum frequency constraint is expressed by the following formula: Formula 12; In the formula: P f-fire This refers to the active power that satisfies the minimum frequency constraint under the boundary conditions of the power grid in the studied area.

4. The frequency stability constraint solution for a given new energy grid connection scenario as described in claim 3, characterized in that: In step S5, the method for obtaining the actual active power output of the thermal power unit is expressed by the following formula: P L +P S =P N +P T +P G Formula Thirteen; P fire =(P L +P S -P N -P T )-(P water +P ps +P es +P g-new Formula Fourteen; In the formula: P S P represents the total network loss under the total load of the power grid in the studied area; N P represents the DC external power received under the boundary conditions of the power grid in the studied area; T P represents the AC external power received under the boundary conditions of the power grid in the studied area; G P is the AC power source under the boundary conditions of the power grid in the studied area. G =P fire +P water +P ps +P es +P g-new Formula 15; Among them, P g-new The active power contribution of new energy indicators under the boundary conditions of the power grid in the studied area: P g-new =P g-windg +P g-pv Formula Sixteen.

Images