Wind-light-pumped storage combined system intraday rolling economic dispatching method considering prediction deviation

Abstract

The invention relates to a wind-light-pumping-storage combined system intraday rolling economic dispatching method considering prediction deviation, which comprises the following steps of: firstly, considering factors which need to be considered in intraday rolling optimization dispatching in multiple aspects, determining an objective function of an intraday optimization dispatching model, and secondly, considering intraday new energy prediction deviation into the intraday optimization model, and finally, on the basis of rolling optimization, constructing an intra-day rolling optimization model and deciding an intra-day optimization scheduling scheme by considering the limited column writing constraint condition of each unit of the combined scheduling system. According to the design method, on the basis of rolling optimization, starting and stopping cost, a stable output index, daily operation water balance and daily operation thermal power total generating capacity deviation are considered, and an intra-day rolling optimization model considering intra-day new energy prediction deviation is established; and the joint system scheduling optimization which can cope with supply and demand imbalance caused by prediction errors under different time scales within the day and fully consider the characteristics of the pumping and storage system is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optimized dispatching, and in particular to a method for intraday rolling economic dispatching of a wind-solar-pumped storage combined system taking into account prediction deviation. Background Art

[0002] In recent years, the development of new energy in my country has shown a multipolar trend, especially wind energy, solar energy and other renewable energy sources known as "new coal" have expanded rapidly in the power sector. Wind power, photovoltaics and other energy sources have promoted profound changes in the energy structure, gradually reduced dependence on traditional fossil fuels, and increased the proportion of renewable energy in energy supply, thereby significantly reducing carbon emissions. However, new energy sources are affected by natural conditions and have the characteristics of randomness and intermittency. Wind power is often weak during the day and strong at night, with higher output in winter, spring and autumn, and lower output in summer; photovoltaic power has high output during the day and almost no output at night. This puts higher requirements on the peak load and frequency regulation of the power system, and at the same time affects the stability of the system due to insufficient rotational inertia, which has an impact on the security of the power grid. In order to solve the above problems, "new energy + energy storage" is widely regarded as an important technical means. Among them, pumped storage, as the most mature and economical energy storage method, is widely used in the power system. Pumped storage power stations can adjust the random fluctuations of wind power and photovoltaic power generation into smooth and stable power output through optimized scheduling and fast and flexible adjustment of hydropower units, thereby effectively solving the volatility problem in wind and solar power generation.

[0003] Since the accuracy of new energy prediction is different at different time scales, the new energy prediction error needs to be considered in the scheduling optimization of the intraday time scale to maintain load balance. Therefore, in the intraday optimization scheduling model, it is necessary to consider the new energy error and consider the indicators of the pumped storage system from many aspects. The objective function considered in intraday optimization is often different from that of other scales, so it is necessary to first consider the various indicators of the pumped storage power station system to determine the objective function of the optimization model. At the same time, considering the operating characteristics of each unit of the wind-solar-pumped storage system, constraints are added to the intraday scheduling optimization model to obtain the intraday scheduling optimization plan that achieves system supply and demand balance. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a daily rolling economic dispatch method for a wind-solar-pumped storage combined system taking into account prediction deviations. Based on dynamic rolling optimization, indicators are formulated by taking into account various aspects of daily pumped storage operation characteristics, the objective function of the optimization model is determined, and constraints are listed based on the characteristics of the multi-source combined system. An intraday rolling optimization model taking into account new energy prediction deviations is established, thereby achieving a supply and demand balance that fully utilizes the pumped storage characteristics on an intraday scale.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: the present invention designs a wind-solar-pumped storage combined system intraday rolling economic dispatch considering the forecast deviation, which is used for intraday optimal dispatch considering the forecast error of new energy, and is characterized by comprising the following steps:

[0006] Step A. Consider various factors that need to be considered for intraday rolling optimization scheduling, determine the objective function of the intraday optimization scheduling model, and then proceed to step B;

[0007] Step B. Considering the intraday new energy forecast deviation into the intraday optimization model, write the constraint conditions by considering the limit columns of each unit in the joint dispatching system, and then proceed to step C;

[0008] Step C. Finally, based on rolling optimization, build an intraday rolling optimization model according to the objective function and constraints obtained in the above steps.

[0009] As a preferred technical solution of the present invention, in step A, the model objective function is determined according to the following steps A01 to A02:

[0010] Step A01. Consider the daily operation characteristics of the wind-solar-pumped storage system and construct optimization indicators:

[0011] Consider the start-stop costs, specifically:

[0012]

[0013] Among them, n i is the number of units in the pumped storage power station; S on and S off They are startup and shutdown costs respectively; and They respectively indicate whether the jth unit of the pumped-storage power station is in power generation or pumping condition.

[0014] Consider the output stability index, specifically:

[0015]

[0016] Among them, n f is the number of thermal power units; is the output of the i-th thermal power unit at time t; is the output of the jth unit of the i-th power station at time t;

[0017] Consider the daily operating water balance indicators, specifically:

[0018]

[0019] in, is the amount of water in and out of the pumped storage power station at time T; It is the amount of water that will be stored in the pumped storage power station at time T in the previous day plan.

[0020] Considering the deviation penalty of the total power generation of daily thermal power generation, the specific penalty is:

[0021]

[0022] In the formula, Q init is the total deviation of thermal power generation up to the last moment; is the output of the i-th thermal power unit at time t in the day-ahead plan.

[0023] Step A02. Determine the objective function of intraday optimization based on the indicator:

[0024]

[0025] Where F represents the objective function, λ so ,λ so ,λ so ,λ so Represent the weights of the four indicators respectively.

[0026] As a preferred technical solution of the present invention, in step B, in order to balance the new energy prediction error, the load balance constraint is listed as follows:

[0027]

[0028] in, Compared with the ultra-short-term forecast, the new energy forecast deviation is a little bit.

[0029] 4. According to the method for intraday rolling economic dispatch of a wind-solar-pumped storage system considering prediction deviation in claim 1, it is characterized in that in step B, the operating conditions of the thermal power unit are considered, and the constraints are listed as follows:

[0030] (a) Upper and lower limits of output

[0031]

[0032] Where Pf i,min ,Pf i,max are the upper and lower limits of the output of the i-th thermal power unit respectively.

[0033] (b) Hill climbing constraint

[0034]

[0035] Where Pf i,R is the maximum ramp rate of thermal power unit i.

[0036] As a preferred technical solution of the present invention, in step B, considering the operating conditions of the pumped storage unit, the constraints are listed as follows:

[0037] (a) Upper and lower limits of power generation capacity of pumped storage units

[0038]

[0039] Where P i,g,min ,P i,g,max are the minimum and maximum values ​​of the power generation capacity of the i-th unit in the pumped storage power station respectively; is a continuous variable, which represents the power generation of the i-th unit of the pumped storage power station at time t.

[0040] (b) Unique constraint on unit operating conditions

[0041]

[0042] In the formula, They are all 0 or 1 variables. When they are 1, they respectively indicate that the i-th unit of the pumped-storage power station is in pumping, generating, or shut down conditions.

[0043] (3) Unit output power expression

[0044] At present, most of the domestic pumped storage power stations still use fixed-speed units. When in the power generation state, the power generation power can be continuously adjusted within the adjustment range. When in the pumping state, they usually only consume grid electricity at the rated power.

[0045]

[0046] Where P i,p is the pumping power of the i-th unit of the pumped-storage power station.

[0047] (4) Constraints on the conversion of operating conditions in adjacent time periods

[0048] The conversion between power generation and pumping conditions requires a transition to a shutdown state, so it cannot be completed in adjacent time periods. The constraints are as follows:

[0049]

[0050] (5) Mutually exclusive constraints on power station internal operating conditions

[0051] Due to the influence of hydraulic factors, pumped power generation conditions cannot exist simultaneously in the same power station. The constraints are as follows:

[0052]

[0053] (6) Upper and lower reservoir water volume constraints

[0054]

[0055] In the formula, E i,up,min ,E i,up,max ,E i,down,min ,E i,down,max are the minimum and maximum values ​​of water volume in the upper and lower reservoirs of the i-th power station respectively; are continuous variables, representing the amount of water in and out of the reservoir of the i-th power station at time t.

[0056] As a preferred technical solution of the present invention, in step C, a rolling solution of an intraday optimization model is established based on the objective function obtained in step A and the constraint conditions obtained in step B.

[0057] The multi-microgrid area division method based on source-load uncertainty simulation described in the present invention adopts the above technical scheme and has the following technical effects compared with the prior art: the intraday rolling economic dispatch method of the wind-solar-pumped storage combined system designed by the present invention considering the prediction deviation takes into account the operating characteristics of different power stations and lists the model constraints; it takes into account the diversified optimization dispatching indicators, with the start-stop cost, daily operating water balance, daily thermal power plan deviation and output stability as optimization indicators, for intraday optimization dispatching, taking into account the new energy prediction error, making full use of the flexibility of the pumped storage power station, achieving load balance on the intraday scale, and ensuring stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flowchart of the intraday rolling economic dispatch of the wind-solar-pumped storage combined system designed by the present invention taking into account the forecast deviation;

[0059] Table 1 is a system structure table used in the embodiment of the present invention;

[0060] Figure 2 The recent forecast of new energy sources in the past day;

[0061] Figure 3 It is an intraday revision plan;

[0062] Figure 4 It is the comparison between the plan before the day and the revised plan within the day in scenario 1;

[0063] Figure 5 It is the comparison between the plan before and the revised plan during the day in scenario 2;

[0064] Figure 6 It is a comparison of the scenario’s plan 3 days ago and the revised plan within the day. DETAILED DESCRIPTION

[0065] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0066] Example: Intraday rolling economic dispatch of wind-solar-pumped storage combined system considering forecast deviation is used for intraday optimal dispatch considering forecast error of new energy. In practical applications, such as Figure 1 As shown, it is characterized in that it includes the following steps:

[0067] Step A. Consider various factors that need to be considered for intraday rolling optimization scheduling, determine the objective function of the intraday optimization scheduling model, and then proceed to step B;

[0068] Step B. Considering the intraday new energy forecast deviation into the intraday optimization model, write the constraint conditions by considering the limit columns of each unit in the joint dispatching system, and then proceed to step C;

[0069] Step C. Finally, based on rolling optimization, build an intraday rolling optimization model according to the objective function and constraints obtained in the above steps.

[0070] As a preferred technical solution of the present invention, in step A, the model objective function is determined according to the following steps A01 to A02:

[0071] Step A01. Consider the daily operation characteristics of the wind-solar-pumped storage system and construct optimization indicators:

[0072] Consider the start-stop costs, specifically:

[0073]

[0074] Among them, n i is the number of units in the pumped storage power station; S on and S off They are startup and shutdown costs respectively; and They respectively indicate whether the jth unit of the pumped-storage power station is in power generation or pumping condition.

[0075] Consider the output stability index, specifically:

[0076]

[0077] Among them, n f is the number of thermal power units; is the output of the i-th thermal power unit at time t; is the output of the jth unit of the i-th power station at time t;

[0078] Consider the daily operating water balance indicators, specifically:

[0079]

[0080] in, is the amount of water in and out of the pumped storage power station at time T; It is the amount of water that will be stored in the pumped storage power station at time T in the previous day plan.

[0081] Considering the deviation penalty of the total power generation of daily thermal power generation, the specific penalty is:

[0082]

[0083] In the formula, Q init is the total deviation of thermal power generation up to the last moment; is the output of the i-th thermal power unit at time t in the day-ahead plan.

[0084] Step A02. Determine the objective function of intraday optimization based on the indicator:

[0085]

[0086] Where F represents the objective function, λ so ,λ so ,λ so ,λ so Represent the weights of the four indicators respectively.

[0087] As a preferred technical solution of the present invention, in step B, in order to balance the new energy prediction error, the load balance constraint is listed as follows:

[0088]

[0089] in, Compared with the ultra-short-term forecast, the new energy forecast deviation is a little bit.

[0090] 4. According to the method for intraday rolling economic dispatch of a wind-solar-pumped storage system considering prediction deviation in claim 1, it is characterized in that in step B, the operating conditions of the thermal power unit are considered and the constraints are listed as follows:

[0091] (a) Upper and lower limits of output

[0092]

[0093] Where Pf i,min ,Pf i,max are the upper and lower limits of the output of the i-th thermal power unit respectively.

[0094] (b) Hill climbing constraint

[0095]

[0096] Where Pf i,R is the maximum ramp rate of thermal power unit i.

[0097] As a preferred technical solution of the present invention, in step B, considering the operating conditions of the pumped storage unit, the constraints are listed as follows:

[0098] (a) Upper and lower limits of power generation capacity of pumped storage units

[0099]

[0100] Where P i,g,min ,P i,g,max are the minimum and maximum values ​​of the power generation capacity of the i-th unit in the pumped storage power station respectively; is a continuous variable, which represents the power generation of the i-th unit of the pumped storage power station at time t.

[0101] (b) Unique constraint on unit operating conditions

[0102]

[0103] In the formula, They are all 0 or 1 variables. When they are 1, they respectively indicate that the i-th unit of the pumped-storage power station is in pumping, generating, or shut down conditions.

[0104] (3) Unit output power expression

[0105] At present, most of the domestic pumped storage power stations still use fixed-speed units. When in the power generation state, the power generation power can be continuously adjusted within the adjustment range. When in the pumping state, they usually only consume grid electricity at the rated power.

[0106]

[0107] Where P i,p is the pumping power of the i-th unit of the pumped-storage power station.

[0108] (4) Constraints on the conversion of operating conditions in adjacent time periods

[0109] The conversion between power generation and pumping conditions requires a transition to a shutdown state, so it cannot be completed in adjacent time periods. The constraints are as follows:

[0110]

[0111] (5) Mutually exclusive constraints on power station internal operating conditions

[0112] Due to the influence of hydraulic factors, pumped power generation conditions cannot exist simultaneously in the same power station. The constraints are as follows:

[0113]

[0114] (6) Upper and lower reservoir water volume constraints

[0115]

[0116] In the formula, E i,up,min ,E i,up,max ,E i,down,min ,E i,down,max are the minimum and maximum values ​​of water volume in the upper and lower reservoirs of the i-th power station respectively; are continuous variables, representing the amount of water in and out of the reservoir of the i-th power station at time t.

[0117] As a preferred technical solution of the present invention, in step C, a rolling solution of an intraday optimization model is established based on the objective function obtained in step A and the constraint conditions obtained in step B.

[0118] The above-mentioned technical solution is applied in practice. The system contains a pumped storage power station, which contains four pumped storage units. The system contains a thermal power unit, which has three thermal power units. The detailed information of the pumped storage unit is shown in Table 1.

[0119] like Figure 2 The figure shows the new energy forecast data for the day before. The forecast period T is selected as 30 minutes, and the rolling step is 5 minutes. Under this time scale, in order to eliminate the new energy forecast error, the day-ahead plan is optimized and solved on a rolling basis. In one day, 288 rollings are required.

[0120] Table 1 Pumped storage unit parameters

[0121]

[0122] Based on the above regional division model, this section carries out numerical simulation calculations on a 64-bit desktop computer configured with AMD R7-3700X 3.59-GHz CPU and 32-GBRAM, uses MATLAB-2020b / YALMIP for optimization modeling, and calls Gurobi9.5 to solve the optimization problem.

[0123] Figure 3 The figure shows the intraday correction plan. The horizontal axis represents time in hours, and the vertical axis represents power in kilowatts. It can be seen from the intraday rolling optimization correction plan that in order to cope with the impact of new energy forecast errors at different time scales, thermal power units and pumped storage units coordinate and correct output to achieve power balance. Next, the scenarios of the three time periods are analyzed in detail.

[0124] Figure 4The figure shows the comparison between the day-ahead plan and the day-ahead revised plan in scenario 1. The horizontal axis represents time in hours, and the vertical axis represents power in kilowatts. Scenario 1 is the time period from 6:00 to 9:00. In the day-ahead plan during this time period, the pumped storage unit is in the power generation state. At this time, the output of the four units is adjustable, and the output adjustment does not cause frequent start and stop. In order to ensure that the difference between the day-ahead revised opportunity of the thermal power unit and the power generation planned in the day-ahead is not too large, in the case of scenario 1, in order to offset the forecast error of new energy, the flexibility of the pumped storage unit is fully utilized, and the load power balance is mainly achieved by correcting the output of the pumped storage unit. Figure 5 The figure shows the comparison between the day-ahead plan and the revised plan for the day in scenario 2. The horizontal axis represents time in hours, and the vertical axis represents power in kilowatts. Scenario 2 is the time period from 12:00 to 2:00. During this time period, the output of the thermal power unit in the day-ahead plan is close to the minimum value, and the upper and lower adjustment margins are insufficient. It can be seen from the scheduling results that when the adjustment capacity of the thermal power unit is insufficient, the pumped storage unit will cooperate with the thermal power unit to adjust the output to meet the load balance. Although the pumped storage unit is in a pumping state at this time, adjusting the output will cause additional starts and stops compared to the day-ahead plan, but minimizing the number of starts and stops is based on the premise of successfully meeting the supply and demand balance. Figure 6 The figure shows the comparison of the plan before and the revised plan during the day in scenario 3. The horizontal axis represents time in hours, and the vertical axis represents power in kilowatts. Scenario 3 is the time period from 21:00 to 23:00. During this time period, all thermal power units are started and are not close to the minimum and maximum output values. In the case of sufficient up and down adjustment margins for thermal power units, in order to minimize the number of starts and stops of pumped storage units, reduce the start and stop costs and the condition of the maintenance units, and extend the life of pumped storage units, the thermal power units adjust their output to resist the prediction errors of new energy.

[0125] The intraday optimal economic dispatch scheme considering the prediction error of new energy proposed in the present invention takes into account the prediction error of new energy at different scales in the intraday optimal dispatch model, and considers the indicators of the pumped storage system from multiple aspects as the objective function of the dispatch optimization model; considering the operating characteristics of each unit in the wind-solar-pumped storage system, constraints are added to the intraday dispatch optimization model, and an intraday dispatch optimization scheme that realizes the balance of supply and demand of the system is obtained, which makes full use of the flexibility of pumped storage and smoothes the uncertain fluctuations of new energy in the system containing a high proportion of new energy.

[0126] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for intraday rolling economic dispatch of a wind-solar-pumped storage system considering prediction deviation, which is used for intraday optimal dispatch considering prediction error of new energy, and is characterized by: The steps include: Step A. Consider various factors that need to be considered for intraday rolling optimization scheduling, determine the objective function of the intraday optimization scheduling model, and then proceed to step B; Step B. Considering the intraday new energy forecast deviation into the intraday optimization model, write the constraint conditions by considering the limit columns of each unit in the joint dispatching system, and then proceed to step C; Step C. Finally, based on rolling optimization, an intraday rolling optimization model is constructed according to the objective function and constraints obtained in the above steps.

2. According to claim 1, a method for intraday rolling economic dispatch of a wind-solar-pumped storage system taking into account prediction deviation is characterized in that: In step A, the model objective function is determined according to the following steps A01 to A02: Step A01. Consider the daily operation characteristics of the wind-solar-pumped storage system and construct optimization indicators: Consider the start-stop costs, specifically: Among them, n i is the number of units in the pumped storage power station; S on and S off They are startup and shutdown costs respectively; and They respectively indicate whether the jth unit of the pumped storage power station is in power generation or pumping operation. Consider the output stability index, specifically: Among them, n f is the number of thermal power units; is the output of the i-th thermal power unit at time t; is the output of the jth unit of the i-th power station at time t; Consider the daily operating water balance indicators, specifically: in, is the amount of water in and out of the pumped storage power station at time T; is the amount of water that the pumped storage power station will store at time T in the previous day plan, Considering the deviation penalty of the total power generation of daily thermal power generation, the specific penalty is: In the formula, Q init is the total deviation of thermal power generation up to the last moment; is the output of the i-th thermal power unit at time t in the day-ahead plan, Step A02. Determine the objective function of intraday optimization based on the indicator: Where F represents the objective function, λ so ,λ so ,λ so ,λ so Represent the weights of the four indicators respectively.

3. According to the method for intraday rolling economic dispatch of a wind-solar-pumped storage system taking into account prediction deviation according to claim 1, it is characterized in that: In step B, in order to balance the new energy prediction error, the load balance constraints are listed as follows: in, Compared with the ultra-short-term forecast, the new energy forecast deviation is a little bit.

4. According to the method for intraday rolling economic dispatch of a wind-solar-pumped storage system taking into account prediction deviation according to claim 1, it is characterized in that: In step B, considering the operating conditions of the thermal power unit, the constraints are listed as follows: (a) Upper and lower limits of output Where Pf i,min ,Pf i,max are the upper and lower limits of the output of the i-th thermal power unit, (b) Hill climbing constraint Where Pf i,R is the maximum ramp rate of thermal power unit i.

5. According to the method for intraday rolling economic dispatch of a wind-solar-pumped storage system taking into account prediction deviation as described in claim 1, it is characterized in that: In step B, considering the operating conditions of the pumped storage unit, the constraints are listed as follows: (a) Upper and lower limits of power generation capacity of pumped storage units Where P i,g,min ,P i,g,max are the minimum and maximum values ​​of the power generation capacity of the i-th unit in the pumped storage power station respectively; is a continuous variable, representing the power generation of the i-th unit of the pumped storage power station at time t. (b) Unique constraint on unit operating conditions In the formula, are all 0,1 variables. When they are 1, they indicate that the i-th unit of the pumped storage power station is in the pumping, generating, and shutdown conditions. (3) Unit output power expression At present, most of the domestic pumped storage power stations still use fixed-speed units. When in the power generation state, the power generation power can be continuously adjusted within the adjustment range. When in the pumping state, it usually only consumes grid power at the rated power. Where P i,p is the pumping power of the i-th unit of the pumped storage power station, (4) Constraints on the conversion of operating conditions in adjacent time periods The conversion between power generation and pumping conditions requires a transition to a shutdown state, so it cannot be completed in adjacent time periods. The constraints are as follows: (5) Mutually exclusive constraints on power station internal operating conditions Due to the influence of hydraulic factors, pumped power generation conditions cannot exist simultaneously in the same power station. The constraints are as follows: (6) Upper and lower reservoir water volume constraints In the formula, E i,up,min ,E i,up,max ,E i,down,min ,E i,down,max are the minimum and maximum values ​​of water volume in the upper and lower reservoirs of the i-th power station respectively; are continuous variables, representing the amount of water in and out of the reservoir of the i-th power station at time t.

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