Multi-time scale virtual flexible load scheduling method and system for coping with power fluctuations

Abstract

The present invention discloses a multi-time scale virtual flexible load dispatching method and system for coping with power fluctuations, and relates to the technical field of power system optimization dispatching. The method includes: suppressing wind power fluctuations through flexible adjustment strategies, wherein the flexible adjustment strategies include virtual flexible load adjustment strategies with second-level response, virtual flexible load adjustment strategies with minute-level response, and virtual flexible load adjustment strategies with hour-level response; establishing a multi-scale optimization dispatching target model, and adjusting the power of thermal power units, energy storage, self-contained power plants, and cold and hot loads based on the virtual flexible load adjustment strategy with the goal of minimizing power generation costs to complete load dispatching. The present invention overcomes the limitation of the prior art that only a single controllable energy source or controllable load is used to absorb wind power. The complexity of the power system is low, and the efficiency of the power system for absorbing wind power is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system optimization dispatching, and in particular to a multi-time scale virtual flexible load dispatching method and system for coping with power fluctuations. Background Art

[0002] Wind power energy plays an important role in promoting sustainable development strategies due to its renewable characteristics. However, wind power is often volatile, and the climbing ability of thermal power units cannot keep up with the power changes caused by wind power fluctuations. As a result, when the wind power increases, the power of thermal power units decreases slowly, which is prone to wind abandonment; when the wind power decreases, the power of thermal power units increases slowly, which is prone to load loss, bringing huge challenges to the power system. The existing load dispatching methods for wind power absorption often only consider a single controllable energy source or controllable load for wind power absorption, which has insufficient regulation ability and poor flexibility. The wind power absorption capacity is low, which not only causes energy waste, but also affects the stability of the power system. At the same time, in order to keep up with the speed of change of wind power, blindly pursuing response speed requires more advanced equipment support and relies on more complex calculations, which is difficult to implement. If multiple controllable energy sources or controllable loads are used to absorb wind power, the complexity of the power system will increase significantly. Different controllable energy sources or controllable loads cannot achieve efficient data exchange and information sharing, which increases the difficulty of wind power absorption in the power system. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the load scheduling methods for wind power consumption in the prior art, such as insufficient adjustment ability, low flexibility and high difficulty in wind power consumption, and to provide a multi-time scale virtual flexible load scheduling method and system for coping with power fluctuations. By constructing a short-time control strategy for charging and discharging and a long-time translation control strategy for cold and hot loads, wind power is consumed on multiple time scales, and the working time of cold and hot loads is shifted by using peak and valley electricity prices, which plays a role in load translation and peak shaving and valley filling, alleviates the limitations of the climbing ability of thermal power units, and improves the utilization efficiency of wind power energy.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] The multi-time-scale virtual flexible load scheduling method for coping with power fluctuations includes:

[0006] Construct short-term control strategies for charging and discharging as well as long-term shifting control strategies for hot and cold loads;

[0007] A multi-scale optimization scheduling target model is established. Based on the climbing capability of thermal power units, short-term charging and discharging control strategies, and long-term translation control strategies of cold and hot loads, the power of thermal power units, charging and discharging facilities, and cold and hot loads is adjusted through virtual flexible load adjustment with the goal of minimizing power generation costs to complete load scheduling.

[0008] As a basic regulation tool, thermal power units play an important role in dealing with wind power fluctuations. Since wind power fluctuations and thermal power unit ramping cannot be coordinated and matched within a certain period of time, it will cause wind abandonment or load loss. Therefore, the conventional scheme relies heavily on the ramping ability of thermal power units, and requires auxiliary adjustment through fast and accurate virtual flexible loads to make up for the lack of climbing ability. Virtual load refers to a load that can absorb or release electrical energy, and flexible load refers to an adjustable and controllable load. In this scheme, an energy unit that has the dual functions and roles of power source and load and can change its own power size, which is equivalent to changing the system power, is defined as a virtual flexible load.

[0009] Since the cold and hot loads have a 45-minute insulation inertia characteristic, they can ask the power grid for electricity in advance or delay, and use the peak and valley electricity prices to shift the working time of the cold and hot loads, which plays a role in shifting the load, shaving the peak and filling the valley, and alleviating the peak-shaving pressure of the system. Since the cold and hot loads have increased autonomous controllability, they can cooperate with the thermal power units in advance to reduce the dependence of the regulation process on the climbing ability of the thermal power units, and do not rely on fast and accurate complex calculation control strategies, and at the same time can reduce the electricity costs of users' cold and hot loads; although the cold and hot loads are not electrical loads, they can be used as virtual loads by using the electricity-cold and hot energy conversion characteristics; since the working time period of the cold and hot loads is transferred to other time periods, it is equivalent to increasing or reducing the system load and can be used as a flexible load. Therefore, the cold and hot loads are used as virtual flexible loads participating in the thermal power cold standby response to the hourly load peak shaving and valley filling response.

[0010] In this solution, multiple controllable energy sources and controllable loads are designed as virtual flexible loads, overcoming the limitation of the existing technology that only a single controllable energy source or controllable load is used to absorb wind power. At the same time, since different controllable energy sources or controllable loads only participate in their own virtual flexible load adjustment strategies, the adjustment strategies between each other do not affect or conflict, and different controllable energy sources or controllable loads do not need to exchange data and share information, so the complexity of the power system is low, and the efficiency of the power system for wind power absorption is improved.

[0011] The dispatching target of the multi-scale optimization dispatching target model is to minimize the wind power abandonment cost, load loss cost, thermal power unit cost and the cost of calling virtual flexible load. In this scheme, since the wind power abandonment and load loss phenomena are significantly reduced, the wind power abandonment cost and load loss cost are significantly reduced. Due to the call of virtual flexible load, the cost will increase slightly. Therefore, through the multi-scale optimization dispatching target model, the power generation cost is minimized and the economic benefit is improved.

[0012] Preferably, the short-time charging and discharging control strategy includes a virtual flexible load regulation strategy with a response in seconds and a virtual flexible load regulation strategy with a response in minutes. A virtual flexible load regulation strategy with a response in seconds is established based on the energy storage charging and discharging control strategy; and a virtual flexible load regulation strategy with a response in minutes is established based on the captive power plant charging or discharging strategy.

[0013] Since energy storage has the function of rapidly charging and discharging to the power grid in seconds, the charging and discharging of energy storage according to the ups and downs of wind power is equivalent to increasing or reducing the system load, and can be used as a virtual load; the charging and discharging power of energy storage can be adjusted, and can be used as a flexible load; therefore, energy storage is used as a virtual flexible load that participates in the AGC dispatch of thermal power to respond to and suppress the second-level fluctuations of wind power.

[0014] Since captive power plants have the characteristic of purchasing and selling electricity from the power grid at the minute level, when they purchase or sell electricity from the system, it is equivalent to increasing or reducing the system load and can be used as a virtual load. The power of captive power plants purchasing and selling electricity from the system can be adjusted and can be used as a flexible load. Therefore, captive power is used as a virtual flexible load participating in thermal power standby scheduling to respond to minute-level wind power curtailment.

[0015] Preferably, the virtual flexible load regulation strategy with second-level response based on the energy storage charging and discharging control strategy is specifically:

[0016] Wind power fluctuations include wind power fluctuations upward within seconds and wind power fluctuations downward within seconds. When the wind power fluctuates upward within seconds, the energy storage charges to smooth out the fluctuations. When the wind power fluctuates downward within seconds, the energy storage discharges to smooth out the fluctuations.

[0017] Preferably, the capacity of the energy storage matches the wind power fluctuation amount, and the wind power fluctuation amount is evaluated using a relative difference:

[0018] ,

[0019] Where: The absolute difference refers to the peak output power of the wind power sequence in the entire time domain. and valley value Difference, Wind power installed capacity.

[0020] Preferably, the virtual flexible load regulation strategy with minute-level response is established based on the charging or discharging strategy of the self-provided power plant, specifically: construct an equivalent load, the equivalent load is the difference between the total load of the power grid and the wind power power, when the equivalent load is greater than the maximum output of the thermal power unit, the self-provided power plant discharges, and the part exceeding the discharge capacity of the self-provided power plant will lose load; when the equivalent load is less than the maximum output of the thermal power unit, the self-provided power plant charges, and the part exceeding the charging capacity of the self-provided power plant will abandon the wind.

[0021] As a preferred embodiment, the change in the self-purchased electricity or self-sold electricity of the self-provided power plant for:

[0022] ,

[0023] ,

[0024] Where: is the original abandoned wind power or the original lost load power, The current abandoned wind power or current lost load power, To purchase and sell electricity for self-use, , The start and end time of self-sale and purchase of electricity. Indicates the number of times the original wind power was abandoned or the original load power was lost. Indicates the number of times wind power is abandoned or load power is lost.

[0025] Preferably, the hourly virtual flexible load regulation strategy is established based on adjusting the start-up time of cold and hot loads, specifically: utilizing the heating and cooling inertia of cold and hot loads, delaying the start-up of cold and hot loads in the peak electricity price time period, and starting the cold and hot loads in advance in the valley electricity price time period, that is, shifting the time periods of cold and hot loads.

[0026] Preferably, the multi-scale optimization scheduling target model is specifically:

[0027] ,

[0028] In the formula, The cost of wind power curtailment is is the load loss cost, is the cost of thermal power unit, To call the virtual flexible load cost, They correspond to the virtual flexible load regulation strategy of second-level response, the virtual flexible load regulation strategy of minute-level response and the virtual flexible load regulation strategy of hour-level response respectively; n=1, 2, 3;

[0029] ,

[0030] ,

[0031] ,

[0032] ,

[0033] Where: is the wind power, The power after wind power abandonment, The time of wind power abandonment, Penalty costs for wind power curtailment; is the load power, is the load power after load loss, is the load loss time, Penalty costs for lost load; The total time of thermal power operation; is the number of thermal power units, Representative The power size of the thermal power unit; , , are the quadratic, primary and constant coefficients of the cost of thermal power generation, respectively; To call the virtual flexible load cost, To call the virtual flexible load power, the virtual flexible load regulation strategy corresponding to the second-level response, the virtual flexible load regulation strategy corresponding to the minute-level response and the virtual flexible load regulation strategy corresponding to the hour-level response respectively; n=1, 2, 3; The time to call the virtual flexible load.

[0034] Preferably, the constraints of the multi-scale optimization scheduling target model include system power balance constraints, upper and lower limit constraints of thermal power unit output, thermal power unit climbing constraints, energy storage power constraints, energy storage power constraints, self-provided power output upper and lower limit constraints, self-provided power climbing constraints, cold and hot load power constraints and cold and hot load time constraints;

[0035] The system power balance constraint is ;

[0036] The upper and lower limits of thermal power unit output are ;

[0037] The climbing constraint of thermal power unit is ,in, is the minimum downward ramp rate allowed for thermal power units, The maximum upward ramp rate allowed for thermal power units;

[0038] The energy storage power constraint is ;

[0039] The energy storage capacity constraint is ;

[0040] The cooling and heating load power constraints are ;

[0041] The time constraints of cooling and heating loads are ;

[0042] The upper and lower limit constraints of self-generated power output are the same as those of thermal power units, and the climbing constraints of self-generated power are the same as those of thermal power units.

[0043] Preferably, the virtual flexible load regulation strategy with second-level response also includes utilizing supercapacitor charging and discharging control strategy to perform wavelet decomposition on wind power fluctuations, allocating high-frequency fluctuations to supercapacitors and low-frequency fluctuations to energy storage. Decomposing wind power fluctuations into different frequency components and allocating them to the most suitable equipment for processing (supercapacitors and energy storage) can improve the reliability and flexibility of the entire system.

[0044] Multi-time scale virtual flexible load dispatching system to cope with power fluctuations, including:

[0045] Wind power fluctuation detection module, used to detect wind power fluctuation;

[0046] A strategy generation module is used to generate a virtual flexible load regulation strategy according to wind power fluctuations. The virtual flexible load regulation strategy includes a virtual flexible load regulation strategy with a second-level response, a virtual flexible load regulation strategy with a minute-level response, and a virtual flexible load regulation strategy with an hour-level response.

[0047] Basic dispatching module, used to dispatch the power of thermal power units;

[0048] Auxiliary dispatch module, used to dispatch the power of energy storage, self-provided power plants and cooling and heating loads;

[0049] The system executes a multi-time-scale virtual flexible load scheduling method to cope with power fluctuations during operation.

[0050] The beneficial effects of the present invention are as follows: the present invention designs a variety of controllable energy sources and controllable loads as virtual flexible loads, overcoming the limitation of the prior art that only a single controllable energy source or controllable load is used to absorb wind power. At the same time, since different controllable energy sources or controllable loads only participate in their own virtual flexible load adjustment strategies, the adjustment strategies between each other do not affect or conflict, and different controllable energy sources or controllable loads do not need to exchange data and share information, so the complexity of the power system is low, and the efficiency of the power system for wind power absorption is improved.

[0051] The present invention reduces the power generation cost to the maximum extent and improves the economic benefits through a multi-scale optimization scheduling target model; through a virtual flexible load scheduling method, the supply and demand relationship of the power system can be better balanced, and the system instability caused by power fluctuations can be reduced, which is helpful to improve the reliability and stability of the power system, avoid the problem of increased electricity costs and reduced wind power energy utilization due to the limitations of the climbing ability of thermal power units, and ensure the continuity and safety of power supply.

[0052] The present invention can stratify and simplify complex power system scheduling problems by constructing control strategies of different time scales, thereby reducing the complexity of overall calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a flow chart of the present invention;

[0054] Figure 2 This is a comparison chart of the climbing rates of various energy sources of the present invention;

[0055] Figure 3 It is a schematic diagram of the relationship between increasing and reducing the cooling and heating loads and temperature changes of the present invention;

[0056] Figure 4 This is a comparison diagram of wind power fluctuations after the present invention calls for energy storage;

[0057] Figure 5 It is a diagram of the cold and hot loads and the load comparison used by the present invention. DETAILED DESCRIPTION

[0058] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0059] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0060] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0061] Embodiment 1: Multi-time scale virtual flexible load scheduling method for coping with power fluctuations, such as Figure 1 As shown, including:

[0062] The wind power fluctuation is suppressed by a flexible regulation strategy, wherein the flexible regulation strategy includes a virtual flexible load regulation strategy with a second-level response, a virtual flexible load regulation strategy with a minute-level response, and a virtual flexible load regulation strategy with an hour-level response.

[0063] A virtual flexible load regulation strategy with second-level response is established based on energy storage charging and discharging control strategy;

[0064] Establish a virtual flexible load regulation strategy with minute-level response based on the charging or discharging strategy of the self-provided power plant;

[0065] Establish hourly virtual flexible load regulation strategy based on adjusting the start-up time of cold and hot loads;

[0066] A multi-scale optimization scheduling target model is established. Based on the virtual flexible load adjustment strategy, the power of thermal power units, energy storage, captive power plants and cold and hot loads is adjusted with the goal of minimizing power generation cost to complete load scheduling.

[0067] As a basic regulation tool, thermal power units play an important role in dealing with wind power fluctuations. Since wind power fluctuations and thermal power unit ramp-up cannot be coordinated and matched within a certain period of time, wind abandonment or load loss will occur, and virtual flexible loads are needed for auxiliary regulation. Virtual loads refer to loads that can absorb or release electrical energy, and flexible loads refer to adjustable and controllable loads. In this solution, energy units that have the dual functions and roles of power sources and loads and can change their own power size, which is equivalent to changing the system power, are defined as virtual flexible loads. Figure 2 As shown in the figure, the ideal 1-minute and 5-minute ramp power changes of thermal power units are 25MW and 125MW, and the 1-minute and 5-minute maximum power changes of wind power are 86MW and 177MW. The ramp capacity of thermal power units is seriously insufficient within 5 minutes. Energy storage has a fast response capability, and the supplement of self-generated electricity can make up for the ramp capacity of thermal power, reduce wind abandonment or prevent load loss. Figure 3 As shown in the figure, increasing or reducing 90MW of cold and hot loads will change the temperature from 20℃ to 24℃ (human body temperature range) within 45 minutes. Therefore, the cold and hot loads have a certain period of heat preservation inertia, and a certain amount of power can be supplied in advance or delayed.

[0068] Since energy storage has the function of rapidly charging and discharging to the power grid in seconds, the charging and discharging of energy storage according to the ups and downs of wind power is equivalent to increasing or reducing the system load, and can be used as a virtual load; the charging and discharging power of energy storage can be adjusted, and can be used as a flexible load; therefore, energy storage is used as a virtual flexible load that participates in the AGC dispatch of thermal power to respond to and suppress the second-level fluctuations of wind power.

[0069] Since captive power plants have the characteristic of purchasing and selling electricity from the power grid at the minute level, when they purchase or sell electricity from the system, it is equivalent to increasing or reducing the system load and can be used as a virtual load. The power of captive power plants purchasing and selling electricity from the system can be adjusted and can be used as a flexible load. Therefore, captive power is used as a virtual flexible load participating in thermal power standby scheduling to respond to minute-level wind power curtailment.

[0070] Since the cold and hot loads have the characteristic of large inertia of 45 minutes of thermal insulation, they can ask the power grid for electricity in advance or delay, and the peak and valley electricity prices can be used to shift the working time of the cold and hot loads, which plays the role of shifting peak and filling valley, alleviating the peak-shaving pressure of the system, and at the same time reducing the electricity costs of users' cold and hot loads; although the cold and hot loads are not electrical loads, they can be used as virtual loads by utilizing the electricity-cold and hot energy conversion characteristics; since the working time period of the cold and hot loads is transferred to other time periods, it is equivalent to increasing or reducing the system load and can be used as a flexible load. Therefore, the cold and hot loads are used as virtual flexible loads participating in the cold standby of thermal power to respond to the hourly load peak-shaving and valley-filling response.

[0071] In this solution, multiple controllable energy sources and controllable loads are designed as virtual flexible loads, overcoming the limitation of the existing technology that only a single controllable energy source or controllable load is used to absorb wind power. At the same time, since different controllable energy sources or controllable loads only participate in their own virtual flexible load adjustment strategies, the adjustment strategies between each other do not affect or conflict, and different controllable energy sources or controllable loads do not need to exchange data and share information, so the complexity of the power system is low, and the efficiency of the power system for wind power absorption is improved.

[0072] The dispatching target of the multi-scale optimization dispatching target model is to minimize the wind power abandonment cost, load loss cost, thermal power unit cost and the cost of calling virtual flexible load. In this scheme, since the wind power abandonment and load loss phenomena are significantly reduced, the wind power abandonment cost and load loss cost are significantly reduced. Due to the call of virtual flexible load, the cost will increase slightly. Therefore, through the multi-scale optimization dispatching target model, the power generation cost is minimized and the economic benefit is improved.

[0073] The virtual flexible load regulation strategy based on the energy storage charging and discharging control strategy to establish a second-level response is specifically:

[0074] Wind power fluctuations include wind power fluctuations upward within seconds and wind power fluctuations downward within seconds. When the wind power fluctuates upward within seconds, the energy storage charges to smooth out the fluctuations. When the wind power fluctuates downward within seconds, the energy storage discharges to smooth out the fluctuations.

[0075] The energy storage capacity is matched with the wind power fluctuation amount, and the wind power fluctuation amount is evaluated by relative difference:

[0076] ,

[0077] Where: The absolute difference refers to the peak output power of the wind power sequence in the entire time domain. and valley value Difference, Wind power installed capacity.

[0078] The virtual flexible load regulation strategy for minute-level response based on the self-provided power plant charging or discharging strategy is specifically as follows: construct an equivalent load, which is the difference between the total load of the power grid and the wind power. When the equivalent load is greater than the maximum output of the thermal power unit, the self-provided power plant discharges, and the part exceeding the discharge capacity of the self-provided power plant will lose load; when the equivalent load is less than the maximum output of the thermal power unit, the self-provided power plant charges, and the part exceeding the charging capacity of the self-provided power plant will abandon the wind.

[0079] The change in the self-purchased electricity or self-sold electricity of the self-provided power plant for:

[0080] ,

[0081] ,

[0082] Where: is the original abandoned wind power or the original lost load power, The current abandoned wind power or current lost load power, To purchase and sell electricity for self-use, , The start and end time of self-sale and purchase of electricity. Indicates the number of times the original wind power was abandoned or the original load power was lost. Indicates the number of times wind power is abandoned or load power is lost.

[0083] The hourly virtual flexible load regulation strategy based on adjusting the start-up time of cold and hot loads is specifically: utilizing the heating and cooling inertia of cold and hot loads, delaying the start-up of cold and hot loads in the peak electricity price time period, and starting the cold and hot loads in advance in the valley electricity price time period, that is, shifting the time periods of cold and hot loads.

[0084] The multi-scale optimization scheduling target model is specifically:

[0085] ,

[0086] In the formula, The cost of wind power curtailment is is the load loss cost, is the cost of thermal power unit, To call the virtual flexible load cost, They correspond to the virtual flexible load regulation strategy of second-level response, the virtual flexible load regulation strategy of minute-level response and the virtual flexible load regulation strategy of hour-level response respectively; n=1, 2, 3;

[0087] ,

[0088] ,

[0089] ,

[0090] ,

[0091] Where: is the wind power, The power after wind power abandonment, The time of wind power abandonment, Penalty costs for wind power curtailment; is the load power, is the load power after load loss, is the load loss time, Penalty costs for lost load; The total time of thermal power operation; is the number of thermal power units, Representative The power size of the thermal power unit; , , are the quadratic, primary and constant coefficients of the cost of thermal power generation, respectively; To call the virtual flexible load cost, To call the virtual flexible load power, the virtual flexible load regulation strategy corresponding to the second-level response, the virtual flexible load regulation strategy corresponding to the minute-level response and the virtual flexible load regulation strategy corresponding to the hour-level response respectively; n=1, 2, 3; The time to call the virtual flexible load.

[0092] The constraints of the multi-scale optimization scheduling target model include system power balance constraints, upper and lower limits of thermal power unit output constraints, thermal power unit ramp constraints, energy storage power constraints, energy storage power constraints, self-provided power output upper and lower limits constraints, self-provided power ramp constraints, cold and hot load power constraints, and cold and hot load time constraints;

[0093] The system power balance constraint is ;

[0094] The upper and lower limits of thermal power unit output are ;

[0095] The climbing constraint of thermal power unit is ,in, is the minimum downward ramp rate allowed for thermal power units, is the maximum upward ramp rate allowed for thermal power units;

[0096] The energy storage power constraint is ;

[0097] The energy storage capacity constraint is ;

[0098] The cooling and heating load power constraints are ;

[0099] The time constraints of cooling and heating loads are ;

[0100] The upper and lower limit constraints of self-generated power output are the same as those of thermal power units, and the climbing constraints of self-generated power are the same as those of thermal power units.

[0101] Multi-time scale virtual flexible load dispatching system to cope with power fluctuations, including:

[0102] Wind power fluctuation detection module, used to detect wind power fluctuation;

[0103] A strategy generation module is used to generate a virtual flexible load regulation strategy according to wind power fluctuations. The virtual flexible load regulation strategy includes a virtual flexible load regulation strategy with a second-level response, a virtual flexible load regulation strategy with a minute-level response, and a virtual flexible load regulation strategy with an hour-level response.

[0104] Basic dispatching module, used to dispatch the power of thermal power units;

[0105] Auxiliary dispatch module, used to dispatch the power of energy storage, self-provided power plants and cooling and heating loads;

[0106] The system executes a multi-time-scale virtual flexible load scheduling method to cope with power fluctuations during operation.

[0107] Specifically, this embodiment uses a total installed capacity of 1750MW of public thermal power in a certain area, a total installed capacity of 1700MW of wind power (of which the maximum wind power is about 1300MW due to wind speed and power restrictions), a total installed capacity of 1050MW of self-provided power plants (of which the power that can be sold to the regional power grid is about 200MW-450MW), a total load capacity of 1800MW of the power grid (of which the cold and hot load capacity is 300MW), and assumes that energy storage with a maximum power variation of 50MW is equipped as a case to analyze various energy and load characteristics. The parameters of the self-provided power plant and the thermal power unit are the same, and the parameters of the thermal power unit are shown in Table 1.

[0108] Table 1 Parameters of thermal power units

[0109]

[0110] The penalty cost for wind power curtailment is 500 yuan / MW.h, the cost of energy storage call-up is 400 yuan / MW.h, the cost of self-contained power plants and cold and hot load call-up is 207.3 yuan / MW.h, the GDP per kilowatt-hour of load loss is 5,700 yuan / MW.h, and the area that can call for cold and hot loads in the region is 12 million square meters.

[0111] Wind power fluctuation power, wind power fluctuation power after calling virtual flexible load Figure 4 As shown by Figure 4 It can be seen that after calling on energy storage, the wind power fluctuations are smoothed, and the maximum and minimum fluctuation power and absolute difference are shown in Table 2.

[0112] Table 2 Changes in the absolute relative difference of calling energy storage

[0113]

[0114] The amount of wind power abandoned and the amount of load lost before and after the self-generated electricity is called are shown in Table 3.

[0115] Table 3 Comparison of wind abandonment and load loss in self-provided power plants

[0116]

[0117] The wind curtailment, load loss costs and call costs are shown in Table 4.

[0118] Table 4 Comparison of self-provided electricity call costs

[0119]

[0120] After the cold and hot loads are called, the system load is as follows Figure 5 The original load, the maximum power, the minimum power and the peak-to-valley difference of the load after calling the cold and hot loads are shown in Table 5.

[0121] Table 5 Calling cooling and heating load

[0122]

[0123] The original load peak-to-valley difference was 303.7MW. After the cold and hot loads were called up, the peak-to-valley difference was 242.8MW, and the peak-to-valley difference decreased by 60.9MW, reducing the lost load by 33.1MW.h and reducing the lost load cost by 189,000 yuan. The costs of thermal power and self-owned power plants without calling up the cold and hot loads were 1.9917 million and 1.6007 million yuan respectively. After the call up, the costs of thermal power and self-owned power plants were 1.9925 million and 1.4467 million yuan respectively, and the unit operating cost was reduced by 153,200 yuan. The cold and hot loads were called up by 540MW.h in total, with a call up cost of 108,400 yuan, creating a total benefit of 233,800 yuan.

[0124] In summary, this embodiment has the following beneficial effects:

[0125] A variety of controllable energy sources and controllable loads are designed as virtual flexible loads, overcoming the limitation of the existing technology that only a single controllable energy source or controllable load is used to absorb wind power. At the same time, since different controllable energy sources or controllable loads only participate in their own virtual flexible load adjustment strategies, the adjustment strategies between each other do not affect or conflict, and different controllable energy sources or controllable loads do not need to exchange data and share information, so the complexity of the power system is low, and the efficiency of the power system for wind power absorption is improved.

[0126] Through the multi-scale optimization scheduling target model, the power generation cost is reduced to the maximum extent and the economic benefits are improved; through the virtual flexible load scheduling method, the supply and demand relationship of the power system can be better balanced, and the system instability caused by power fluctuations can be reduced, which helps to improve the reliability and stability of the power system and ensure the continuity and safety of power supply.

[0127] By constructing control strategies at different time scales, complex power system scheduling problems can be layered and simplified, thereby reducing the overall computational complexity.

[0128] Embodiment 2: The multi-time scale virtual flexible load dispatching method for coping with power fluctuations has the same principle and implementation method as Embodiment 1, except that the virtual flexible load regulation strategy with second-level response also includes the use of supercapacitor charging and discharging control strategy to perform wavelet decomposition on wind power fluctuations, allocate high-frequency fluctuations to supercapacitors, and allocate low-frequency fluctuations to energy storage. Decomposing wind power fluctuations into different frequency components and allocating them to the most suitable equipment for processing (supercapacitors and energy storage) can improve the reliability and flexibility of the entire system.

[0129] The process of wavelet decomposition is as follows: according to the characteristics of wind power fluctuation, select the appropriate wavelet basis function; according to the fluctuation frequency range of wind power, determine the number of wavelet decomposition layers; perform wavelet decomposition on wind power data to obtain different frequency components (detail coefficients) and an approximate coefficient (low-frequency component).

[0130] The decomposed high-frequency components are assigned to supercapacitors. Supercapacitors have extremely high charge and discharge rates and are suitable for quickly responding to high-frequency fluctuations. The low-frequency components are assigned to the energy storage system. Although the energy storage system does not respond as fast as the supercapacitor, it has a larger energy storage capacity and is suitable for handling lower-frequency fluctuations.

[0131] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0132] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A multi-time scale virtual flexible load dispatching method for coping with power fluctuations, characterized by: include: Construct short-term control strategies for charging and discharging as well as long-term shifting control strategies for hot and cold loads; A multi-scale optimization scheduling target model is established. Based on the ramping capability of thermal power units, short-term charging and discharging control strategies, and long-term shifting control strategies for cold and hot loads, the power of thermal power units, charging and discharging facilities, and cold and hot loads is adjusted through virtual flexible load regulation with the goal of minimizing power generation costs to complete load scheduling. The short-term charge and discharge control strategy includes a virtual flexible load regulation strategy with a second-level response and a virtual flexible load regulation strategy with a minute-level response. A virtual flexible load regulation strategy with a second-level response is established based on the energy storage charge and discharge control strategy; a virtual flexible load regulation strategy with a minute-level response is established based on the self-provided power plant charging or discharging strategy; The long-term shift control strategy of the cold and hot loads is specifically as follows: utilizing the heating and cooling inertia of the cold and hot loads, delaying the start of the cold and hot loads in the peak electricity price period, and starting the cold and hot loads in advance in the valley electricity price period, that is, shifting the time period of the cold and hot loads; The multi-scale optimization scheduling target model is specifically: In the formula, The cost of wind power curtailment is is the load loss cost, C f (t) is the cost of thermal power unit, C rn (t n ) is the cost of calling virtual flexible load, t n They correspond to the virtual flexible load regulation strategy of second-level response, the virtual flexible load regulation strategy of minute-level response and the virtual flexible load regulation strategy of hour-level response respectively; n=1, 2, 3; Where: P W is the wind power, is the power after wind power abandonment, T is the wind power abandonment time, c w Penalty cost for wind power curtailment; P L is the load power, is the load power after load loss, T' is the load loss time, c L is the penalty cost for load loss; T” is the total time of thermal power operation; N is the number of thermal power units, P f,i represents the power of the i-th thermal power unit; a i ,b i ,c i are the quadratic, primary and constant coefficients of the cost of thermal power generation; C rn is the cost of calling virtual flexible load, P rn To call the virtual flexible load power, corresponding to the virtual flexible load regulation strategy of second-level response, the virtual flexible load regulation strategy of minute-level response and the virtual flexible load regulation strategy of hour-level response respectively; n = 1, 2, 3; T″′ is the time for calling virtual flexible load.

2. The multi-time scale virtual flexible load scheduling method for coping with power fluctuations according to claim 1 is characterized in that: The virtual flexible load regulation strategy based on the energy storage charging and discharging control strategy to establish a second-level response is specifically: Wind power fluctuations include wind power fluctuations upward within seconds and wind power fluctuations downward within seconds. When the wind power fluctuates upward within seconds, the energy storage charges to smooth out the fluctuations. When the wind power fluctuates downward within seconds, the energy storage discharges to smooth out the fluctuations.

3. The multi-time scale virtual flexible load scheduling method for coping with power fluctuations according to claim 2 is characterized in that: Its characteristics are: The energy storage capacity is matched with the wind power fluctuation amount, and the wind power fluctuation amount is evaluated by relative difference: Where: E AR The absolute difference refers to the peak output power of the wind power sequence in the entire time domain. and valley value Difference, Cap is the installed capacity of wind power.

4. The multi-time scale virtual flexible load scheduling method for coping with power fluctuations according to claim 1 is characterized in that: The virtual flexible load regulation strategy for minute-level response based on the self-provided power plant charging or discharging strategy is specifically as follows: construct an equivalent load, which is the difference between the total load of the power grid and the wind power. When the equivalent load is greater than the maximum output of the thermal power unit, the self-provided power plant discharges; when the equivalent load is less than the maximum output of the thermal power unit, the self-provided power plant charges.

5. The multi-time-scale virtual flexible load scheduling method for coping with power fluctuations according to claim 4 is characterized in that: The change in the self-purchased power or self-sold power of the self-provided power plant ΔQ AW for: Where: P M is the original abandoned wind power or the original lost load power, P W,ES is the current abandoned wind power or current lost load power, E up is the self-generated power purchase and sale, t1 and t2 are the start and end time of self-generated power purchase and sale, n1 represents the number of times the original wind power is abandoned or the original load power is lost, and n2 represents the number of times the current wind power is abandoned or the current load power is lost.

6. The multi-time scale virtual flexible load scheduling method for coping with power fluctuations according to claim 1 is characterized in that: The constraints of the multi-scale optimization scheduling target model include system power balance constraints, upper and lower limits of thermal power unit output constraints, thermal power unit ramp constraints, energy storage power constraints, energy storage power constraints, self-provided power output upper and lower limits constraints, self-provided power ramp constraints, cold and hot load power constraints, and cold and hot load time constraints; The system power balance constraint is The upper and lower limits of thermal power unit output are The climbing constraint of thermal power unit is Among them, R down is the minimum downward ramp rate allowed for thermal power units, R up is the maximum upward ramp rate allowed for thermal power units; The energy storage power constraint is The energy storage capacity constraint is The cooling and heating load power constraints are The time constraints of cooling and heating loads are The upper and lower limit constraints of self-generated power output are the same as those of thermal power units, and the climbing constraints of self-generated power are the same as those of thermal power units.

7. The multi-time scale virtual flexible load scheduling method for coping with power fluctuations according to claim 1 is characterized in that: The virtual flexible load regulation strategy with second-level response also includes utilizing supercapacitor charging and discharging control strategy to perform wavelet decomposition on wind power fluctuations, allocating high-frequency fluctuations to supercapacitors and low-frequency fluctuations to energy storage.

8. A multi-time scale virtual flexible load dispatching system for coping with power fluctuations, characterized by: include: Wind power fluctuation detection module, used to detect wind power fluctuation; A strategy generation module is used to generate a virtual flexible load regulation strategy according to wind power fluctuations. The virtual flexible load regulation strategy includes a virtual flexible load regulation strategy with a second-level response, a virtual flexible load regulation strategy with a minute-level response, and a virtual flexible load regulation strategy with an hour-level response. Basic dispatching module, used to dispatch the power of thermal power units; Auxiliary dispatch module, used to dispatch the power of energy storage, self-provided power plants and cooling and heating loads; When running, the system executes the multi-time-scale virtual flexible load scheduling method for coping with power fluctuations as described in claim 1.

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