Partition electric power balance measuring and calculating method for promoting new energy consumption

Abstract

The invention relates to a partition power balance measuring and calculating method for promoting new energy consumption, and the method comprises the steps: constructing a load prediction model, predicting the load of each partition at 8760 o'clock in the future, constructing a time sequence simulation model with the maximum new energy comprehensive output of each partition, and calculating the load of each partition at 8760 o'clock in the future. Power balance, new energy annual utilization hours, inter-partition line transmission capacity, unit output, unit ramp rate, energy storage charging and discharging and the like are used as constraint conditions, and the power supply gap condition of each partition is simulated and measured. According to the method, the power supply gap of each subarea is measured and calculated by taking new energy to promote absorption and power grid subarea balance as targets, and a direction is provided for a controllable load regulation and control mode or energy storage layout.

Description

Technical Field

[0001] This application belongs to the technical field of distribution network operation, and specifically relates to a method for calculating the partition power balance to promote the consumption of new energy. Background Art

[0002] In recent years, the new energy industry in China has developed rapidly, and the installed capacities of wind power and photovoltaic power are in the leading position in the world. With the increasingly widespread application of new energy in the power grid, the intermittency and volatility of its power generation have brought more uncertainty problems to system planning.

[0003] When planning and designing a power system, the balance between power supply and demand is one of the issues that must be considered. The power balance problem in power system planning mainly studies how the power sources, grids, loads, and energy storage in the power system cooperate with each other, and reasonably distributes the installed capacities and power generation amounts of each power station to cope with various situations such as the output fluctuations of generating units, system pre-arranged power outages and maintenance plans, and load shedding during faults.

[0004] Traditional power quantity balance focuses on the rigid boundaries of system parameters and adopts simplified constraints, such as the DC power flow equation of the network, or directly considers that the total power supply capacity is greater than the total load, and performs balance according to conditions such as network load characteristics, wiring modes, and load forecasts. In the environment of high proportion of new energy access to the power grid, the limitation of traditional research lies in the lack of research on the coordinated output of traditional energy and new energy. Therefore, the present invention proposes a method for calculating the partition power balance to promote the consumption of new energy, models and analyzes the power output of each partition power source, obtains the power supply gap of each partition under the maximum consumption of new energy, the calculation method is simple, the result is clear, and it can better solve the partition balance problem. Summary of the Invention

[0005] The purpose of the embodiments of this application is to provide a method for calculating the partition power balance to promote the consumption of new energy, aiming at promoting the consumption of new energy and achieving the grid partition balance, calculating the power supply gap of each partition, and providing a direction for the controllable load regulation method or energy storage layout.

[0006] To achieve the above purpose, this application provides the following technical solutions:

[0007] The embodiments of this application provide a method for calculating the partition power balance to promote the consumption of new energy, including the following specific steps:

[0008] Construct a load forecasting model to forecast the load at 8760 points in the future years for each partition;

[0009] Construct a time series simulation model with the maximum comprehensive output of new energy for each partition;

[0010] Calculate the power supply gap situation of each partition, and clarify the controllable load regulation method and energy storage layout direction.

[0011] The load forecasting model refers to a forecasting model constructed by using the exponential smoothing method in time series based on the historical 8760-point hourly loads of each sub-region to forecast the 8760-point hourly load in the future year. The calculation formula is as follows:

[0012]

[0013] Among them, y j is the actual value of the j-th period;

[0014] is the actual value of the (j + 1)-th period;

[0015] are the first-order exponential smoothing values of the (j - 1)-th period and the j-th period;

[0016] α is the smoothing coefficient, and 0 < α < 1.

[0017] The objective function of the chronological simulation model with the maximum comprehensive output of new energy in each sub-region is as follows:

[0018]

[0019] Among them, I is the total number of sub-regions;

[0020] i is a certain sub-region;

[0021] T is the total length of time;

[0022] t is the time step;

[0023] is the wind power output of sub-region i at time t;

[0024] is the photovoltaic power output of sub-region i at time t.

[0025] The constraint conditions of the chronological simulation model include power balance constraint, annual utilization hours constraint of new energy, line transmission capacity constraint between sub-regions, unit output constraint, unit ramp rate constraint, and energy storage charge and discharge constraint;

[0026] The power balance constraint means that the sum of the unit output of each sub-region and the power of the inter-sub-region connection line is equal to the sub-region load. The calculation formula is as follows:

[0027]

[0028] Among them, is the output of the other M units in sub-region i at time t except for wind power and photovoltaic power;

[0029] is the power of the inter-sub-region connection line in sub-region i at time t;

[0030] is the load of partition i at time period t.

[0031] The constraint on the annual utilization hours of new energy means that the ideal values of the annual utilization hours of wind power and photovoltaic power are set for the region. When solving the model, the ratio of the sum of the annual outputs of wind power and photovoltaic power to the installed capacities of wind power and photovoltaic power under the action of energy storage is calculated to determine whether the set ideal value is reached. Finally, the annual utilization hours of new energy in the model result shall not be lower than the set ideal value. The calculation formula is:

[0032]

[0033] where H a is the annual utilization hours of new energy;

[0034] Q is the annual power generation;

[0035] P ic is the installed capacity.

[0036] The constraint on the transmission capacity of the line between partitions means that the load rate of the connection line between two adjacent partitions exceeds 80%. The calculation formula is:

[0037]

[0038] where L r is the line load rate;

[0039] L max is the upper limit of the line transmission capacity.

[0040] The constraint on the output of the unit means that the output of the units other than wind power and photovoltaic power and the output of wind power and photovoltaic power do not exceed the upper and lower limits. The calculation formula is:

[0041]

[0042]

[0043]

[0044] where P d,m,min and P d,m,max are the upper and lower limits of the output of the units other than wind power and photovoltaic power;

[0045] P w,min and P w,max are the upper and lower limits of the wind power output;

[0046] P p,min and P p,max are the upper and lower limits of the photovoltaic power output.

[0047] The calculation formula for the constraint on the unit ramp rate is:

[0048]

[0049] wherein, is the downward and upward ramp rate of the unit;

[0050] Δt is the time interval.

[0051] The charge-discharge constraint of the energy storage refers to the charge / discharge power constraint and energy constraint of the energy storage device, and the calculation formula is:

[0052]

[0053]

[0054] E s,min ≤E s,t ≤E s,max

[0055] wherein, is the charge / discharge power of the energy storage device;

[0056] is the maximum charge / discharge power of the energy storage device, representing the charge-discharge capacity of the energy storage device;

[0057] E s,t is the energy state of the energy storage device;

[0058] E s,min and E s,max are the upper and lower limits of the energy of the energy storage device;

[0059] is the efficiency factor considering energy loss in the charge / discharge process,

[0060] Compared with the prior art, the beneficial effects of the present invention are:

[0061] The present invention coordinates the output of traditional energy and new energy at 8760 points, clarifies the power supply gap, and can provide technical support for reliable load supply, flexible load and controllable unit regulation methods, and energy storage capacity configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0063] Figure 1: Flowchart of a method for calculating the zonal power balance to promote the consumption of new energy in an embodiment of the present invention.

[0064] Figure 2 : Diagram of the power balance of the power sources, loads, and energy storage in Zone 1 in an embodiment of the present invention.

[0065] Figure 3 : Diagram of the power balance of the power sources, loads, and energy storage in Zone 2 in an embodiment of the present invention. Detailed implementation manners

[0066] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application. It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0067] The term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0068] The terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and cannot be construed as indicating or implying relative importance, nor can it be construed as requiring or implying any actual relationship or order between these entities or operations.

[0069] As Figure 1 shown, a method for calculating the zonal power balance to promote the consumption of new energy in this embodiment is specifically as follows:

[0070] (1) Construct a load forecasting model to forecast the load at 8760 points in the future years for each zone.

[0071] Based on the load at 8760 points in the historical three years for each zone, an exponential smoothing method in time series is used to construct a forecasting model to forecast the load at 8760 points in the future years. The calculation formula is:

[0072]

[0073] where y j is the actual value of the jth period; is the actual value of the (j + 1)th period; are the first exponential smoothing values of the (j - 1)th and jth periods; α is the smoothing coefficient, and 0 < α < 1.

[0074] (2) Construct a time-series simulation model with the maximum comprehensive new energy output in each sub-region.

[0075] 1. The objective function of the model is:

[0076]

[0077] Among them, I is the total number of sub-regions; i is a certain sub-region; T is the total time length; t is the time step, set to hours; is the wind power output of sub-region i at time t; is the photovoltaic power output of sub-region i at time t.

[0078] 2. The constraint conditions of the model include power balance constraint, annual utilization hours constraint of new energy, line transmission capacity constraint between sub-regions, unit output constraint, unit ramp rate constraint, and energy storage charge and discharge constraint.

[0079] (1) The power balance constraint is:

[0080]

[0081] Among them, is the output of the other M units in sub-region i at time t except for wind power and photovoltaic power; is the power of the interconnection line between sub-regions in sub-region i at time t; is the load of sub-region i at time t.

[0082] (2) The annual utilization hours constraint of new energy is:

[0083]

[0084] Among them, H a is the annual utilization hours of new energy; Q is the annual power generation; P ic is the installed capacity.

[0085] (3) The line transmission capacity constraint between sub-regions is:

[0086]

[0087] Among them, L r is the line load rate; L max is the upper limit of the line transmission capacity.

[0088] (4) The unit output constraint is:

[0089]

[0090]

[0091]

[0092] Among them, P d,m,min , P d,m,max are the upper and lower limits of the output of the remaining units other than wind power and photovoltaic; P w,min , P w,max are the upper and lower limits of wind power output; P p,min , P p,max are the upper and lower limits of photovoltaic output.

[0093] (5) The ramp rate constraint of the unit is:

[0094]

[0095] Among them, is the downward and upward ramp rate of the unit; Δt is the time interval, and Δt = 1h is taken.

[0096] (6) The charge and discharge constraint of the energy storage is:

[0097]

[0098]

[0099] E s,min ≤E s,t ≤E s,max (8)

[0100] Among them, is the charge / discharge power of the energy storage device; is the maximum charge / discharge power of the energy storage device, which characterizes the charge and discharge capacity of the energy storage device; E s,t is the energy state of the energy storage device; E s,min , E s,max are the upper and lower limits of the energy of the energy storage device; The is the efficiency factor considering energy loss in the charge / discharge process, and the

[0101] (3) Measure the power supply gap situation in each area, and clarify the controllable load regulation method and the energy storage layout direction.

[0102] II. A preferred embodiment of the present invention is:

[0103] The calculation example includes two areas. The basic parameters of the two areas are set as shown in Table 1. The upper limit of wind power and photovoltaic output is considered according to 100% of the installed capacity, and the lower limit is considered according to 0 MW; the upper limit of the thermal power unit output is 100% of the installed capacity, and the lower limit is considered according to 40% of the installed capacity; the upper limit of the energy storage charge and discharge power is considered according to 100% of the capacity, both are taken as 0.9.

[0104] Table 1 Basic Parameter Table

[0105]

[0106] Use Equation (1) to predict the load at 8760 points in the next year for each sub-region, and use Equations (2)-(8) to determine the power supply gap in each sub-region and the new energy power and electricity that can be absorbed by the power grid. As shown in Table 2, the power balance situation of the source, load, and storage in each sub-region is as Figures 2 to 3 shown. It is calculated that power shortages mainly occur in summer and winter, concentrated in the late peak load period. Measures such as controllable loads or increased energy storage can be adopted to ensure power supply.

[0107] Table 2 Power Balance Analysis Result Table

[0108]

[0109]

[0110] The above are only the embodiments of the present application and are not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for calculating the zonal power balance to promote the consumption of new energy, characterized in that, It includes the following specific steps: Construct a load forecasting model to predict the load at 8760 points in the future years for each sub-region; Construct a time-series simulation model with the maximum comprehensive new energy output for each sub-region; Measure the power supply gap situation for each sub-region, and clarify the controllable load regulation method and energy storage layout direction.

2. The method for calculating the zonal power balance to promote the consumption of new energy according to claim 1, wherein, The load forecasting model refers to constructing a forecasting model based on the load at 8760 points in the historical years of each sub-region and using the exponential smoothing method in time series to predict the load at 8760 points in the future years. The calculation formula is: where y j is the actual value in the j-th period; is the actual value of the (j + 1)-th period; are the first-order exponential smoothing values for the (j - 1)-th and j-th periods; α is the smoothing coefficient, and 0 < α < 1.

3. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 1, characterized in that, The objective function of the time-series simulation model with the maximum comprehensive new energy output for each sub-region is: where I is the total number of sub-regions; i is a certain sub-region; T is the total time length; t is the time step; is the wind power output of partition i at time period t; is the PV output of partition i at time period t.

4. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 1, wherein The constraint conditions of the time-series simulation model include power balance constraint, annual utilization hours constraint of new energy, line transmission capacity constraint between sub-regions, unit output constraint, unit ramp rate constraint, and energy storage charge and discharge constraint; The power balance constraint means that the sum of the unit output of each sub-region and the power of the connecting lines between sub-regions is equal to the sub-region load. The calculation formula is: Among them, is the output of the remaining M units in partition i during period t excluding wind power and photovoltaic power; is the power of the inter-zone tie line for zone i at time period t; is the load of partition i at time period t.

5. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 4, characterized in that, The annual utilization hours constraint of new energy means that the ideal annual utilization hours of wind power and photovoltaic power are set in the region. When the model is solved, calculate the ratio of the sum of the annual wind power and photovoltaic power outputs under the action of energy storage to the installed capacity of wind power and photovoltaic power, and judge whether it reaches the set ideal value. Finally, the annual utilization hours of new energy in the model result shall not be lower than the set ideal value. The calculation formula is: Among them, H a is the annual utilization hours of new energy; Q is the annual power generation; P ic is the installed capacity.

6. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 4, characterized in that The line transmission capacity constraint between sub-regions means that the load rate of the connecting line between two adjacent sub-regions exceeds 80%. The calculation formula is: Among them, L r is the line load rate; L max is the upper limit of the line transmission capacity.

7. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 4, characterized in that, The unit output constraint means that the output of the remaining units except wind power and photovoltaic power and the output of wind power and photovoltaic power do not exceed the upper and lower limits. The calculation formula is: Among them, P d,m,min , P d,m,max are the upper and lower limits of the output of the remaining units other than wind power and photovoltaic power; P w,min and P w,max are the upper and lower limits of wind power output; P p,min and P p,max are the upper and lower limits of photovoltaic output power.

8. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 4, characterized in that, The calculation formula for the unit ramp rate constraint is: Among them, are the down-ramp rate and up-ramp rate of the unit; Δt is the time interval.

9. A method for calculating the zonal power balance to promote the consumption of new energy according to claim 4, characterized in that, The energy storage charge and discharge constraint means the charge / discharge power constraint and energy constraint of the energy storage device. The calculation formula is: E s,min ≤E s,t ≤E s,max Among them, is the charge / discharge power of the energy storage device; is the maximum charge / discharge power of the energy storage device, which characterizes the charge / discharge capacity of the energy storage device; E s,t is the energy state of the energy storage device; E s,min and E s,max are the upper and lower limits of the energy of the energy storage device; The efficiency factor considering energy loss during the charge / discharge process

Images