A virtual power plant scheduling method coupled with interruptible load

Abstract

The application provides a virtual power plant scheduling method for coupling interruptible load, with the increase of renewable energy penetration and load demand, the demand for energy storage of virtual power plants, especially large virtual power plants, increases, and the interruptible load, as a user-side energy storage without early investment and widely distributed, has great potential and is an important way to solve the current demand for energy storage. The application determines the scheduling time and scheduling power of the interruptible load as energy storage in the virtual power plant, so as to adapt to the change of renewable energy output power or the load power demand of different virtual power plants; and under the same power demand, by changing the scheduling time or combining the power trading market, a plurality of different scheduling powers are determined, so that the controller determines the most suitable scheduling power in combination with the scheduling cost in the scheduling process. The method provides a train of thought for the utilization of interruptible load energy storage, and meanwhile, the method is simple and has low investment.

Description

Technical Field

[0001] This invention belongs to the technical field of power system control methods, specifically relating to a virtual power plant dispatching method coupled with interruptible loads. Technical Background

[0002] With the rapid development of renewable energy and the continuous advancement of smart grids, virtual power plants have become a promising energy dispatching and management method. Energy storage in virtual power plants, as a crucial controllable unit, is key to the implementation of dispatching strategies. However, due to technological and environmental constraints, the development of energy storage has been slow and its costs remain high. Interruptible loads, as user-side energy storage with flexibility, controllability, and wide distribution, possess extremely high energy storage potential. If interruptible loads can be coupled into virtual power plants as energy storage, the adaptability of virtual power plants to different load demands can be improved, better maintaining the stable operation of virtual power plants. Furthermore, compared to other energy storage methods, the initial investment is lower, meeting the requirements of virtual power plants. The key to dispatching interruptible loads lies in determining their dispatching time and power; therefore, this invention proposes a virtual power plant dispatching method coupled with interruptible loads. Summary of the Invention

[0003] To overcome the problems existing in the prior art, the present invention aims to provide a virtual power plant scheduling method coupled with interruptible loads. This method uses widely distributed and high-potential interruptible loads as energy storage coupled within the virtual power plant, establishing a relationship between scheduling time and scheduling power to meet the load demand of the virtual power plant. This invention is a scheduling method for interruptible load energy storage in a virtual power plant, enabling the virtual power plant to adapt to power demand changes under various operating conditions and improving its adaptability to changes in the output power of renewable energy units and load demand.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A virtual power plant scheduling method coupled with interruptible loads includes the following steps:

[0006] The first step is to determine the critical period and scheduling period for virtual power plant dispatch: the critical period is the base time for dispatching interruptible loads, which is determined by the operating pattern of electric vehicle energy storage and the dispatchable duration of interruptible loads. The scheduling period is an adjustment of the dispatching period for interruptible loads based on the critical period according to different power demands.

[0007] The second step is to propose three different schemes for calculating the output power of interruptible loads based on the scheduling period, according to different working conditions: Scheme 1, which is universal and can adapt to more working conditions; Scheme 2, which can cope with extreme weather conditions and has a higher output power of interruptible loads compared to Scheme 1; and Scheme 3, which can cope with working conditions where the dispatchable power of interruptible loads is insufficient.

[0008] The characteristics and selection criteria of various schemes are as follows: Interruptible loads are invoked by charging energy storage, which then discharges during peak load periods to meet the virtual power plant's needs. The energy storage discharging at night is divided into energy storage vehicle group 1 and energy storage vehicle group 2. Scheme 1 calculates the virtual power plant's power demand for interruptible loads based on the energy demand of energy storage vehicle group 2. This power demand is closely related to changes in the dispatching period and can adjust the dispatching period and power according to various operating conditions. Scheme 2 calculates the power demand of interruptible loads based on the energy demand of energy storage vehicle group 1 or the maximum charging rate. Compared to Scheme 1, this... The power value is high and changes little with the scheduling period. The redundant power will affect the charging and discharging process of energy storage vehicle group 1 and the power demand of fossil energy by the virtual power plant when energy storage vehicle group 2 is connected to the grid. It is suitable for working conditions where the cost of interruptible load dispatching is low and the dispatchable power is high or the power demand is large. Scheme 3 uses the virtual power plant to participate in power trading to purchase electricity, which can share the power demand of the virtual power plant and obtain a lower interruptible load dispatch power than Scheme 1 and Scheme 2. The electricity purchase time of this method is shortened as the scheduling period is advanced and the amount of electricity purchased decreases as the dispatch power increases. It is suitable for working conditions where the dispatchable power of interruptible load is limited.

[0009] The methods for determining the critical time period and dispatch period for virtual power plant dispatch are as follows:

[0010] Electric vehicles coupled in a virtual power plant as energy storage operate on a shift system, with shift changes mostly occurring in the evening. Therefore, t0 is defined as the shift change point for different groups of electric vehicles. Energy storage group 1 connects to the grid before t0, and energy storage group 2 connects after t0. The formula for determining the scheduling period and critical period of the interruptible load is as follows:

[0011] t1=t0+Δt int

[0012] Δt int ≥2

[0013] t′0=t0-Δt adj

[0014] t′1=t1-Δt adj

[0015] Δt adj_min =0.25

[0016] Δt adj ∈[0,1]

[0017] Where: t0 is the electric vehicle shift change time, i.e., the time when electric vehicle energy storage is centrally connected to the grid, h; t1 is the end time of the critical period, h; Δt intt′0 is the maximum duration of the interruptible load, h; t′1 is the start time of the scheduling period, h; Δt is the end time of the scheduling period, h. adj To adjust the time, i.e., the time difference between the scheduling period and the critical period, h; Δt adj The change will alter the charging duration and total charging capacity of energy storage vehicle group 1 and energy storage vehicle group 2 during the scheduling period. ; Δt adj_min The minimum time interval for adjustment is set to 15 minutes (0.25 hours) for the intraday trading market of the power grid; Δt adj The range is [0,1], which is determined by the maximum charging rate of the electric vehicle energy storage battery. Taking the average charging rate as 1C, the charging time for the electric vehicle energy storage newly connected to the virtual power plant cannot be less than 1 hour.

[0018] The calculation logic for Scheme 1, which can adapt to a wider range of working conditions, is as follows:

[0019] Under Option 1, the dispatch power of the interruptible load is determined based on the power demand of energy storage vehicle group 2. The formula for calculating the dispatch power is as follows:

[0020]

[0021] Where: P int1 SOC represents the dispatchable power of the interruptible load in Scheme 1, in MW; SOC is the state of charge (SOC) value of the electric vehicle energy storage, SOC∈(0,1); tar2 The target value of the state of charge (SOC) of energy storage vehicle group 2 at the end of the dispatch period; sur2 η represents the remaining energy stored in energy storage vehicle group 2 when it is connected to the grid, i.e., at time t0; η represents the charging efficiency of the energy storage; Q bat Q represents the rated capacity of energy storage, expressed in MW·h. demand (t0-t′1) represents the power demand of the virtual power plant during the period t0-t′1, in MW·h; P feu (t0-t′1) represents the output power of the fossil fuel unit during the time period t0-t′1, in MW.

[0022] The charging capacity of energy storage vehicle group 1 can then be calculated using the following formula:

[0023] [P int1 ×Δt adj +P feu (t'0-t0)×Δt adj -Q demand [(t'0-t0)]×η=Q charge1 (t'0-t0)

[0024]

[0025] Among them, Pfeu (t'0-t0) represents the output power of the fossil fuel unit during the time period t′0-t0, in MW; Q demand (t'0-t0) represents the electricity demand of the virtual power plant during the period t′0-t0, in MW·h; Q charge1 (t'0-t0) represents the charging amount of energy storage vehicle group 1 during the time period t′0-t0, in MW·h. SOC sur1 This refers to the remaining capacity of energy storage vehicle group 1 when it leaves the grid; Let be the energy storage capacity of energy storage vehicle group 1 at t′0;

[0026] The charging amount of energy storage vehicle group 1 and energy storage vehicle group 2 during the dispatch period is used to meet the peak power demand of the virtual power plant at night that exceeds the supply of fossil fuel units; therefore, the power of energy storage vehicle group 1 and energy storage vehicle group 2 must satisfy the formula:

[0027] SOC ava2 =SOC tar2 -SOC ll

[0028] SOC ava1 =SOC sur1 -SOC loss1 -SOC ll

[0029] (SOC ava1 +SOC ava2 )×Q bat ×μ=Q discharge (t′1-t end )

[0030] Q demnad (t′1-t end )-P feu ×(t end -t′1)=Q bat-need (t′1-t end )

[0031] Q discharge (t′1-t end )≥Q bat-need (t′1-t end )

[0032] Among them: SOC ava1 The available capacity of energy storage unit 1 during peak nighttime hours; SOC ava2 This refers to the available capacity of energy storage unit 2 during peak nighttime hours; SOC ll The lower limit of energy storage discharge; SOC loss1 t represents the power consumption of energy storage vehicle group 1 during the period when it is away from the grid; μ represents the discharge efficiency of energy storage; t represents the power consumption of energy storage vehicle group 1 during the period when it is away from the grid. endThe end time of energy storage discharge, i.e., the intersection of the power demand curve and the output power of the fossil fuel unit, is h; Q demnad (t′1-t end ) for t1-t end Electricity demand of virtual power plants during a given time period, in MW·h; Q discharge (t′1-t end ) for virtual power plant energy storage t1-t end Total discharge capacity during the period, MW·h; Q bat-need (t′1-t end For the virtual power plant in t1-t end Total electricity demand for energy storage during a given time period, in MW·h;

[0033] When Q discharge (t′1-t end )=Q bat-need (t′1-t end Energy storage utilization is highest at SOC (State of Charge). ava2 When the SOC is the same ava1 Minimum; the charging amount Q of energy storage vehicle group 1 during the time period t′0-t0. charge1 (t'0-t0) remains unchanged, meaning the capacity of energy storage vehicle group 1 at time t0 is constant. The remaining SOC of energy storage vehicle group 1 when it leaves the grid sur1 Minimum means that energy storage vehicle group 1 can utilize its own energy storage to discharge more during peak electricity price periods when connected to the virtual power plant, maximizing the revenue from the price difference; at the same time, it uses less output power from fossil fuel units during flat electricity price periods, and the surplus can be used as power for the virtual power plant to participate in the electricity trading market and grid ancillary services.

[0034] When Q discharge (t′1-t end )<Q bat-need (t′1-t end If the interruptible load calculated based on the current adjustment time is insufficient to meet the nighttime power peak requirements, the adjustment time needs to be changed and recalculated.

[0035] To cope with extreme weather conditions, the calculation logic of Scheme 2, which has a higher output power than Scheme 1 in scheduling interruptible loads, is as follows:

[0036] In Scheme 2, the dispatch power of the interruptible load is determined based on the power demand of energy storage vehicle group 1. The formula for calculating the dispatch power is as follows:

[0037]

[0038]

[0039] Where: P int2 Let Q be the dispatch power of the interruptible load in Scheme 2, expressed in MW. charge1 (t′0-t0) represents the charging amount of energy storage vehicle group 1 during the time period t′0-t0, in MW·h; SOC hl The upper limit for charging energy storage; v bat-max C represents the maximum energy storage charging rate; t represents the maximum value of the energy storage charging rate. bat-min The minimum time to fully charge the energy storage is given in hours (h). Scheme two prioritizes the charging process of energy storage vehicle group 1, determining the interruptible load call power based on the fastest charging rate and maximum charging capacity, thus achieving the minimum... Even under extreme weather conditions or when power demand fluctuates significantly, the energy storage vehicle unit 1 can still guarantee the discharge volume during peak periods and the amount of electricity that the virtual power plant can provide for grid auxiliary services.

[0040] Under Scheme 2, the formula for calculating the available capacity of energy storage vehicle group 1 during the peak nighttime power demand is as follows:

[0041]

[0042] (SOC ava1 +SOC ava2 )×Q bat ×μ=Q discharge (t′1-t end )

[0043] Q discharge (t′1-t end )≥Q bat-need (t′1-t end )

[0044] Where, when Q discharge (t′1-t end )<Q bat-need (t′1-t end If the interruptible load calculated based on the current adjustment time is insufficient to meet the nighttime power peak requirements, the adjustment time needs to be changed and the calculation recalculated.

[0045] When Q discharge (t′1-t end )=Q bat-need (t′1-t end Energy storage utilization is highest at (SOC) ava1 If they are the same, then SOC ava2 Minimum, by SOC ava2 The minimum value can determine the output power of the virtual power plant's fossil fuel unit during the time period t0-t′1. The formula for calculating the output power is as follows:

[0046]

[0047] Where: P f ′ eu (t0-t′1) The output power of the fossil fuel unit in Scheme 2 during the time period t0-t′1, MQ.

[0048] Compared to the output power of the fossil fuel unit in Option 1, under the same power demand, P f ′ eu (t0-t′1) <P feu (t0-t′1). P int2 The changes will affect the charging and discharging limits of energy storage unit 1 when it is connected to the grid, and will also affect the demand of the virtual power plant on fossil fuel units when energy storage unit 2 is connected to the grid. Different schemes utilize interruptible loads to improve the virtual power plant's control over each unit, thereby increasing flexibility.

[0049] The calculation logic for Scheme 3, which addresses the situation where interruptible loads have insufficient dispatchable power, is as follows:

[0050] Scheme 3 of the joint control is applicable when the dispatchable load and available power are insufficient in Schemes 1 and 2. It utilizes a virtual power plant to participate in the electricity trading market and purchase electricity from the grid to make up for the power gap. The time for purchasing electricity from the grid is defined as the intersection of the power demand curve and the output power of the fossil fuel units, denoted as t. start The end time of the electricity purchase period is t′0, the start time of interruptible load scheduling is t′0, and the end time is t′1; then the interruptible load call power P of Scheme 3 is... int3 The calculation is as follows:

[0051]

[0052]

[0053] Where: P demand (t′1-t end ) is for t′1-t end Power demand of virtual power plants during time periods, MW Q demand2 (t′1-t end ) is for t′1-t end The energy storage capacity demand of the virtual power plant for energy storage vehicle group 2 during the time period, in MW·h; Q demand (t0-t′1) represents the power demand of the virtual power plant during the time period t0-t′1, in MW·h; during the dispatching period of interruptible loads, the charging amount of energy storage vehicle group 1 is calculated as follows:

[0054]

[0055] Among them, sOCcharge1 Q represents the increase in the state of charge of energy storage vehicle group 1 during the time period t′0-t0; demand (t'0-t0) represents the electricity demand of the virtual power plant during the period t′0-t0, in MW·h; therefore, the amount of electricity to be purchased during the electricity market trading period can be determined based on the change in the state of charge of the energy storage. The formula for calculating the amount of electricity to be purchased is:

[0056]

[0057]

[0058]

[0059] in: The state of charge (SOC) of energy storage vehicle group 1 at time t′0. start1 For energy storage vehicle group 1 in t start State of charge over time; P EM Q represents the average power purchased by virtual power plants participating in the electricity trading market, expressed in MW. demand (t start -t'0) is t start - The power demand of the virtual power plant during time period t′0, in MW·h; In order to obtain the minimum interruptible load call-up, the remaining power of energy storage vehicle group 1 at time t′0 should be the maximum value.

[0060] Compared with the prior art, the advantages of the present invention are as follows:

[0061] This paper proposes a scheduling method to determine the scheduling time and power values ​​for interruptible loads when a virtual power plant (VPS) calls upon them. Three schemes are presented for different scenarios. Under each scheme, a relationship between the scheduling time and power of interruptible loads is established, enabling the VPS to select appropriate scheduling time and power based on varying power demands. This approach is more flexible and accurate, improves energy utilization, and reduces the cost of scheduling interruptible loads. The scheme enhances the adaptability of the VPS to changes in power demand and has greater practical application value. Attached Figure Description

[0062] Figure 1 This is a schematic diagram illustrating the computational logic of the three schemes in the scheduling method.

[0063] Figure 2 The output power of the photovoltaic unit on a typical day selected in the example varies with time.

[0064] Figure 3 This shows how the load demand changes over time in the instance.

[0065] Figure 4The change in energy storage state of charge during different scheduling periods under the control of method scheme one, under the typical daily operating condition of 1.06.

[0066] Figure 5 Under a typical daily operating condition of 1.06, the output power of the interruptible load changes during different scheduling periods under the control of Method Scheme 1.

[0067] Figure 6 The changes in the state of charge of energy storage during different scheduling periods under the control of method scheme one, under the typical daily operating condition of 8.16.

[0068] Figure 7 The changes in the state of charge of energy storage during different scheduling periods under the control of Method Scheme 2 under the typical daily operating condition of 8.16.

[0069] Figure 8 The changes in the state of charge of energy storage during different scheduling periods under the control of Method Scheme 3 under the typical daily operating condition of 8.16.

[0070] Figure 9 Under the typical daily operating condition of 8.16, and under the control of Method Scheme 3, the changes in the electricity purchase period, electricity purchase amount, and interruptible load dispatch power at different time periods are analyzed.

[0071] Figure 10 This is a comparison chart showing the changes in interruptible load output power under the three control schemes of Method 8.16 under typical daily operating conditions. Detailed Implementation

[0072] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0073] This invention proposes a virtual power plant scheduling method coupled with interruptible loads. The virtual power plant, consisting of a 350MW supercritical coal-fired unit, a 100MW photovoltaic unit, an electric bus energy storage facility with a total rated energy storage capacity of 96MW·h, time-varying loads, and interruptible loads, is selected as the research object. Figure 2 The output power of the photovoltaic unit varies over time under the typical operating conditions of the selected days for the example. The four curves represent the output power of the photovoltaic unit under the illumination intensity of the typical days of summer solstice, winter solstice, January 6 (1.06), and August 16 (8.16). The typical days of January 6 and August 16 are selected as the output power variation curves of the photovoltaic unit for the example. Figure 3 This illustrates the variation in load demand over time. The BYD K8 electric bus is used as an example, and its basic parameters are shown in Table 1. The battery state of charge (SOC) range for the electric bus is set between 0.1 and 1. The capacity required for the main operating bus is represented by an SOC of 0.8, and the capacity required for the standby bus is represented by an SOC of 0.3.

[0074] Table 1

[0075] Battery rated capacity (Ah) 540 Battery rated open-circuit voltage (V) 540 Battery pack rated capacity (Ah) 270 Battery pack rated open-circuit voltage (V) 3.2 Battery state of charge range (%) 10-100 Battery charge / discharge voltage range (V) 420-613.2 Rated energy storage of the battery (kWh) 291.6 Maximum permissible continuous charging current (A) 540 Number of batteries connected in series (n) 169 Maximum permissible continuous discharge current (A) 540 Number of battery packs connected in parallel (n) 2 Rated discharge power (540V, 540A) (kW) 291.6

[0076] Based on the above conditions, a dynamic simulation model of a virtual power plant based on energy storage in electric buses was built in APROS software. The calculation process for different schemes is as follows: Figure 1 As shown. Demonstration implementation methods include: calculating the impact of different scheduling times on interruptible load power under the same scheme on two typical sunshine days, and the impact of different scheduling times on interruptible load power under different schemes on the same typical sunshine day. The specific calculation process is as follows:

[0077] 1: Control performance of different scheduling times under a typical solar irradiance of 1.06:

[0078] First, under the typical daily illuminance of 1.06, the formula for calculating the output power of Scheme 1 for interruptible loads is as follows:

[0079]

[0080] In the formula, P int1 Let SOC be the dispatch power of the interruptible load in Scheme 1, in MW; and SOC be the state of charge value of the electric vehicle energy storage, SOC∈(0,1). tar2 The target value of the state of charge (SOC) of energy storage vehicle group 2 at the end of the dispatch period; sur2 η represents the remaining energy stored in energy storage vehicle group 2 when it is connected to the grid, i.e., at time t0; η represents the charging efficiency of the energy storage; Q bat Q represents the rated capacity of energy storage, expressed in MW·h. demand (t0-t′1) represents the power demand of the virtual power plant during the period t0-t′1, in MW·h; P feu (t0-t′1) represents the output power of the fossil fuel unit during the time period t0-t′1, in MW.

[0081] Secondly, the charging capacity of energy storage vehicle group 1 can be calculated using the following formula:

[0082] [P int1 ×Δt adj +P feu ×Δt adj -Q demand [(t'0-t0)]×η=Q charge1 (t'0-t0)

[0083]

[0084] Among them, P feu(t'0-t0) represents the output power of the fossil fuel unit during the time period t′0-t0, in MW; Q demand (t'0-t0) represents the electricity demand of the virtual power plant during the period t′0-t0, in MW·h; Q charge1 (t'0-t0) represents the charging amount of energy storage vehicle group 1 during the time period t′0-t0, in MW·h. SOC sur1 This refers to the remaining capacity of energy storage vehicle group 1 when it leaves the grid; Let t' be the energy storage capacity of energy storage vehicle group 1 at t'0.

[0085] Third, determine whether the power capacity of energy storage vehicle group 1 and energy storage vehicle group 2 meets the requirements:

[0086] SOC ava2 =SOC tar2 -SOC ll

[0087] SOC ava1 =SOC sur1 -SOC loss1 -SOC ll

[0088] (SOC ava1 +SOC ava2 )×Q bat ×μ=Q discharge (t′1-t end )

[0089] Q demnad (t′1-t end )-P feu ×(t end -t′1)=Q bat-need (t′1-t end )

[0090] Q discharge (t′1-t end )≥Q bat-need (t′1-t end )

[0091] Among them: SOC ava1 The available capacity of energy storage unit 1 during peak nighttime hours; SOC ava2 This refers to the available capacity of energy storage unit 2 during peak nighttime hours; SOC ll The lower limit of energy storage discharge; SOC loss1 t represents the power consumption of energy storage vehicle group 1 during the period when it is away from the grid; μ represents the discharge efficiency of energy storage; t represents the power consumption of energy storage vehicle group 1 during the period when it is away from the grid. end The end time of energy storage discharge, i.e., the intersection of the power demand curve and the output power of the fossil fuel unit, is h; Q discharge (t′1-t endFor virtual power plant energy storage at t′1-t end Total discharge capacity during the period, MW·h; Q bat-need (t′1-t end For the virtual power plant at t′1-t end Total electricity demand for energy storage during a given time period, in MW·h.

[0092] When Q discharge (t′1-t end )<Q bat-need (t′1-t end When Q is in a certain state, the current scheduling time cannot complete the target, and the output power value of the interruptible load cannot be obtained. discharge (t′1-t end )≥Q bat-need (t′1-t end When selecting Q, please choose Q. discharge (t′1-t end )=Q bat-need (t′1-t end The charging and discharging limits of energy storage vehicle group 1 when connected to the grid were determined based on the following conditions. The state of charge (SBC) curve of the energy storage unit over time under a typical solar irradiance of 1.06 was obtained as shown in the figure. Figure 4 As shown in the figure, it can be seen that changing the scheduling time and power of interruptible loads can affect the charging and discharging of energy storage in the virtual power plant at different times. This provides options and possibilities for the virtual power plant to cope with changes in power demand and grid ancillary service demand at different times. The method for the output power of interruptible loads as a function of scheduling time on a typical day of 1.06 is shown in the figure. Figure 5 As shown in the figure, it can be seen that as the adjustment time changes, the scheduling time will also change. At the same time, the scheduling power of the interruptible load required to meet the system power demand will change, and will increase as the scheduling time is advanced.

[0093] 2: Under a typical solar irradiance condition of 8.16, compare the dispatching of interruptible loads by the virtual power plant under the three control schemes:

[0094] The calculation process for Scheme 1 is as described in Section 1, yielding the energy storage state of charge versus time curve for a typical day, August 16th, as shown below. Figure 6 As shown in the figure, under the control of Scheme 1, the amount of energy storage charging and discharging will change with different adjustment times.

[0095] The calculation method for Scheme 2 is as follows:

[0096] The formula for calculating the scheduling power of interruptible loads is:

[0097]

[0098]

[0099] Where: P int2 Let Q be the dispatch power of the interruptible load in Scheme 2, expressed in MW. charge1 (t′0-t0) represents the charging amount of energy storage vehicle group 1 during the time period t′0-t0, in MW·h; SOC hl The upper limit for charging energy storage; v bat-max C represents the maximum energy storage charging rate; t represents the maximum value of the energy storage charging rate. bat-min The minimum time, h, is required to fully charge the energy storage.

[0100] The formula for calculating the available capacity of energy storage vehicle group 1 is as follows:

[0101]

[0102] (SOC ava1 +SOC ava2 )×Q bat ×μ=Q discharge (t′1-t end )

[0103] Q discharge (t′1-t end )≥Q bat-need (t′1-t end )

[0104] Where, when Q discharge (t′1-t end )<Q bat-need (t′1-t end When Q is insufficient to achieve the target, the output power value of the interruptible load cannot be obtained. discharge (t′1-t end )=Q bat-need (t′1-t end Energy storage utilization is highest at (SOC) ava1 If they are the same, then SOC ava2 Minimum, by SOC ava2 The minimum value can determine the output power of the virtual power plant's fossil fuel unit during the time period t0-t′1. The formula for calculating the output power is as follows:

[0105]

[0106] Where: P′ feu (t0-t′1) represents the output power (MW) of the fossil fuel unit during the time period t0-t′1 under Method Scheme 2. The curve of the energy storage state of charge versus time under a typical solar irradiance of 8.16 is shown below. Figure 7As shown in the figure, compared with Scheme 1, the change in the interruptible load scheduling time and power under Scheme 2 has a smaller impact on the energy storage charging and discharging process. Although the scheduling time is different, the discharge amount of the virtual power plant is the same during the peak electricity price period.

[0107] The calculation method for Scheme 3 is as follows:

[0108] The time for purchasing electricity from the grid is t. start The end time of the electricity purchase period is t′0, and the start time of interruptible load dispatch is t′0, with an end time of t′1. The formula for calculating the output power of the interruptible load in Scheme 3 is as follows:

[0109]

[0110]

[0111] Where: P demand (t′1-t end ) is for t′1-t end Power demand of virtual power plants during time periods, MW Q demand2 (t′1-t end ) is for t′1-t end The energy storage capacity demand of the virtual power plant for energy storage vehicle group 2 during the time period, in MW·h; Q demand (t0-t′1) represents the power demand of the virtual power plant during the time period t0-t′1, in MW·h.

[0112] During the scheduling period of interruptible loads, the charging amount of energy storage vehicle group 1 is calculated as follows:

[0113]

[0114] Among them, SOC charge1 This refers to the increase in the state of charge of energy storage vehicle group 1 during the time period t′0-t0.

[0115] The formula for calculating the amount of electricity purchased is:

[0116]

[0117]

[0118]

[0119] in: The state of charge (SOC) of energy storage vehicle group 1 at time t′0. start1 For energy storage vehicle group 1 in t start State of charge over time; P EM Q represents the average power purchased by virtual power plants participating in the electricity trading market, expressed in MW.demand (t start -t'0) is t start The power demand of the virtual power plant during the period -t′0, in MW·h. The curve of the energy storage state of charge versus time on a typical day of August 16th is obtained as follows. Figure 8 As shown in the figure, compared to Scheme 1 and Scheme 2, Scheme 3 offers more selectable scheduling times, and the different interruptible load scheduling times have less impact on the charging and discharging of energy storage at different times, making it easier for the system to control energy storage. The changes in electricity purchase time, electricity purchase volume, and interruptible load scheduling power under the typical daily operating condition of August 16 are shown in the figure. Figure 9 As shown in the figure, under the control of Scheme 3, the electricity purchase time, electricity purchase amount, dispatch time, and dispatch power show obvious regularity. As the dispatch time increases, the electricity purchase time decreases, the dispatch power increases, and the electricity purchase amount decreases. The virtual power plant can determine the most suitable dispatch plan based on the regularity and combined with factors such as electricity purchase price and the callable capacity of interruptible loads.

[0120] Finally, under the typical daily operating condition of 8.16, the curves of the interruptible load output power value versus time under the control of the three schemes are compared, such as... Figure 10 As shown in the figure, compared to the three scheduling schemes, Scheme 2 has the highest interruptible load scheduling power and the least significant change in power value with scheduling time, making it more suitable for extreme power demand situations; Scheme 3 has the lowest interruptible load scheduling power, with the scheduling power value inversely proportional to the purchased power value, making it suitable for situations where the output power of the interruptible load is limited; Scheme 1 has a moderate call power value, and the scheduling time and scheduling power show a regular result, making it a more universal and easier-to-schedule scheme. Examples can verify the characteristics and control effects of each scheme as described in the claims.

Claims

1. A virtual power plant scheduling method coupled with interruptible loads, characterized in that: The steps include the following: The first step is to determine the critical period and scheduling period for virtual power plant dispatch: the critical period is the base time for dispatching interruptible loads, which is determined by the operating pattern of electric vehicle energy storage and the dispatchable duration of interruptible loads. The scheduling period is an adjustment of the dispatching period for interruptible loads based on the critical period according to different power demands. The second step is to propose three different schemes for calculating the output power of interruptible loads based on the scheduling period, according to different working conditions: Scheme 1, which is universal and can adapt to more working conditions; Scheme 2, which can cope with extreme weather conditions and has a higher output power of interruptible loads compared to Scheme 1; and Scheme 3, which can cope with working conditions where the dispatchable power of interruptible loads is insufficient. Energy storage vehicle group 1 is The train sets connected to the grid before energy storage train set 2 are... Train sets connected to the power grid later, The time for electric vehicle rotation, i.e., the time for centralized grid connection of electric vehicle energy storage. ; Under Option 1, the dispatch power of the interruptible load is determined based on the power demand of energy storage vehicle group 2. The formula for calculating the dispatch power is as follows: in: The power to schedule interruptible loads in Scheme 1. ; The state of charge (SOC) value for energy storage in electric vehicles. ; The target value for the state of charge of energy storage vehicle group 2 at the end of the scheduling period; In order to ensure that when energy storage vehicle group 2 is connected to the grid... The remaining amount of electricity stored in the energy storage system; For energy storage charging efficiency; This is the end time of the scheduling period. ; The maximum duration of an interruptible load. ; To adjust the time, specifically the time difference between the scheduled period and the critical period, ; For the rated capacity of energy storage, ; for The electricity demand of the virtual power plant during a given time period. ; for The output power of fossil fuel units during a given period ; In Scheme 2, the dispatch power of the interruptible load is determined based on the power demand of energy storage vehicle group 1. The formula for calculating the dispatch power is as follows: in: The scheduling power of the interruptible load in Method Scheme 2. ; This is the start time of the scheduling period. ; For energy storage vehicle group 1 during the time period Internal charge capacity, ; The upper limit for charging energy storage; This represents the maximum energy storage charging rate. ; The minimum time required to fully charge the energy storage. ; Scheme 3 of the joint control is applicable when the dispatchable load and available power are insufficient as in Schemes 1 and 2. It utilizes a virtual power plant to participate in the electricity trading market and purchase electricity from the grid to compensate for the power gap. The time for purchasing electricity from the grid is defined as the intersection of the power demand curve and the output power of the fossil fuel units, denoted as... The end time for purchasing electricity is... The interruptible load balancing start time is The end time is Therefore, the interruptible load call power of Scheme 3 is... The calculation is as follows: in: In order to be in Power demand of the virtual power plant during a given time period, in MW; In order to be in The energy storage capacity demand of the virtual power plant during the time period for energy storage vehicle group 2. ; For the time period The electricity demand of the virtual power plant within the system. ; This refers to the end time of energy storage discharge, which is the intersection of the power demand curve and the output power of the fossil fuel unit. .

2. The virtual power plant scheduling method for coupled interruptible loads according to claim 1, characterized in that: The methods for determining the critical time period and dispatch period for virtual power plant dispatch are as follows: Electric vehicles coupled in the virtual power plant act as energy storage and operate on a shift system, with shifts occurring in the evening; hence the definition. For the shift change points of different groups of electric vehicles, then energy storage vehicle group 1 is in The train sets connected to the grid before, and the energy storage train set 2 are in For train sets connected to the power grid later, the formula for determining the scheduling period and critical period for interruptible loads is as follows: in: This refers to the end time of the critical period. ; The changes will alter the charging duration and total charging capacity of energy storage vehicle group 1 and energy storage vehicle group 2 during the scheduling period.

3. The virtual power plant scheduling method for coupled interruptible loads according to claim 1, characterized in that: The calculation logic for Scheme 1, which can adapt to a wider range of working conditions, is as follows: The charging capacity of energy storage vehicle group 1 can be calculated using the following formula: in, for The output power of fossil fuel units during a given period ; for The electricity demand of the virtual power plant during a given time period. ; For energy storage vehicle group 1 in Charging amount during the period ； This refers to the remaining capacity of energy storage vehicle group 1 when it leaves the grid; For energy storage vehicle group 1 in Energy storage capacity at that time; The charging amount of energy storage vehicle group 1 and energy storage vehicle group 2 during the dispatch period is used to meet the peak power demand of the virtual power plant at night that exceeds the supply of fossil fuel units; therefore, the power of energy storage vehicle group 1 and energy storage vehicle group 2 must satisfy the formula: in: This represents the available capacity of energy storage vehicle group 1 during peak nighttime hours; This is the available capacity of energy storage vehicle group 2 during peak nighttime hours; This represents the lower limit of energy storage discharge. This refers to the power consumption of energy storage vehicle group 1 during the period when it is away from the grid; The discharge efficiency of energy storage; In order to be in The electricity demand of the virtual power plant during a given time period. ; Energy storage for virtual power plants Total discharge capacity during the period ; For virtual power plants Total electricity demand for energy storage during different time periods. ; when The utilization rate of energy storage is highest during the period of time. When the same Minimum; Energy storage vehicle group 1 in Charging volume during the period Unchanging is in The capacity of the energy storage vehicle group 1 at any time The remaining capacity of energy storage vehicle group 1 when it leaves the grid The minimum means that energy storage vehicle group 1 can utilize its own energy storage more during the process of connecting to the virtual power plant to discharge at peak electricity prices, thus maximizing the benefit from the electricity price difference. when If the interruptible load calculated based on the current adjustment time is insufficient to meet the nighttime power peak requirements, the adjustment time needs to be changed and recalculated.

4. The virtual power plant scheduling method for coupled interruptible loads according to claim 3, characterized in that: To cope with extreme weather conditions, the calculation logic of Scheme 2, which has a higher output power than Scheme 1 in scheduling interruptible loads, is as follows: Under Scheme 2, the formula for calculating the available capacity of energy storage vehicle group 1 during the peak nighttime power demand is as follows: Among them, when If the interruptible load calculated based on the current adjustment time is insufficient to meet the nighttime power peak requirements, the adjustment time needs to be changed and the calculation recalculated. when The energy storage utilization rate is highest during this period. If they are the same minimum, by The minimum value can be determined in The output power of the fossil fuel unit in the virtual power plant during a given time period is calculated using the following formula: in: Option 2 in The output power of fossil fuel units during a given period .

5. The virtual power plant scheduling method for coupled interruptible loads according to claim 3, characterized in that: The calculation logic for Scheme 3, which addresses the situation where interruptible loads have insufficient dispatchable power, is as follows: During the scheduling period of interruptible loads, the charging amount of energy storage vehicle group 1 is calculated as follows: in, For energy storage vehicle group 1 during the time period The increase in the state of charge; In order to be in The electricity demand of the virtual power plant during a given time period. Therefore, the amount of electricity to be purchased during the electricity market trading period can be determined based on the changes in the state of charge of the energy storage. The formula for calculating the amount of electricity to be purchased is: in: For energy storage vehicle group 1 in State of charge over time; For energy storage vehicle group 1 in State of charge over time; The average power purchased by virtual power plants participating in the electricity trading market. ; for The electricity demand of the virtual power plant during a given time period. To achieve the minimum number of interruptible load calls, in The remaining power of the energy storage vehicle group 1 should be at its maximum value.

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