Regional integrated energy system flexibility improvement planning method and system

Abstract

The present invention provides a method and system for planning to improve the flexibility of a regional integrated energy system, including: establishing a deterministic planning model, inputting the planning scheme obtained by solving the model into a lower-level flexibility operation verification model; considering the influence of uncertainty according to the flexibility operation verification model, finding the worst operation scenario under the planning scheme; judging whether the planning scheme meets the flexibility requirements under the worst scenario, and directly outputting the planning scheme if the safety constraints meet the requirements through probability; if the requirements are not met, changing the upper-level planning scheme until a solution that meets the flexibility requirements is found. The planning method of the present invention fully considers the uncertainty in RIES, the uncertainty in source, load, and equipment, and effectively responds to three types of uncertain fluctuations through flexibility improvement planning results.

Description

Technical Field

[0001] The present invention relates to the field of power system distribution network planning and operation, and in particular, to a method and system for improving the flexibility of a regional integrated energy system, and in particular to a method and system for improving the flexibility of a regional integrated energy system taking uncertainty into consideration. Background Art

[0002] Natural gas is a clean and efficient energy source and has become one of the most important fossil fuel resources. According to the forecast of the International Gas Union, by 2030, due to the global interest in promoting low-carbon policies, the proportion of natural gas in the world's total primary energy consumption will rise to 28%. At this growth rate, it can be foreseen that by 2050, natural gas will replace oil as the world's largest energy source. With the continuous development of clean energy power generation such as natural gas power generation and cogeneration, the coupling of power system, natural gas system and heating system has been deepened, forming a regional integrated energy system (RIES) with power system as the core, promoting multi-energy complementarity and cascade utilization, helping to improve energy utilization efficiency and achieve sustainable energy development.

[0003] The increase in the proportion of intermittent renewable energy leads to a growing demand for system flexibility. On the one hand, renewable energy such as wind and solar energy bring a lot of variability and uncertainty to the system due to their inherent intermittency and limited controllability. On the other hand, some renewable energy replaces controllable traditional generators, such as nuclear power, natural gas and pumped storage power stations, reducing the system's rotational inertia and highly reliable regulation power. The lack of flexibility in the system will lead to load reduction, wind and solar abandonment, negative prices in the spot market, etc. At the same time, the multi-energy coupling in RIES will make the energy types and energy load demand more diversified, and the uncertainty of multi-energy load will become more complicated. RIES will face more challenges of uncertainty at more levels. Therefore, it is very important to enhance the ability of RIES to regulate multi-energy supply, demand, energy flow and operate it in a safe operating area. Summary of the invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a method and system for planning the flexibility improvement of a regional integrated energy system.

[0005] A method for improving the flexibility of a regional integrated energy system provided by the present invention includes:

[0006] -Establish a deterministic planning model and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model;

[0007] - Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme;

[0008] -Judge whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; if it does not meet the requirements, the upper-level planning scheme is changed until a scheme that meets the flexibility requirements in the worst scenario and is the most economical in non-bad scenarios is found.

[0009] Preferably, the deterministic planning model aims at economic optimization:

[0010]

[0011] Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; are decision variables for expansion, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, expansion is carried out, if the value is 0, no expansion is carried out; It is the decision variable for whether to configure distributed power generation. If the value is 1, it is configured; if the value is 0, it is not configured.

[0012] Preferably, the deterministic planning model includes: power grid operation constraints, natural gas grid constraints and equipment operation constraints.

[0013] Preferably, the flexibility operation verification model verifies whether the planning scheme is in a safe and stable operation area under the worst scenario. The worst scenario is the scenario where the RIES safety constraint is most likely to exceed the limit. The safety verification model takes maximizing the safety constraint offset as the objective function:

[0014]

[0015] Preferably, the flexibility requirement is that the probability of passing the RIES security constraint reaches 1-α,

[0016]

[0017] Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side, and α is the confidence level.

[0018] According to the present invention, a regional integrated energy system flexibility improvement planning system is provided, which includes the following modules:

[0019] Module M1: Establish a deterministic planning model, and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model;

[0020] Module M2: Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme;

[0021] Module M3: Determine whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; if it does not meet the requirements, the upper-level planning scheme is changed until a scheme that meets the flexibility requirements in the worst scenario and has the best economic performance in non-bad scenarios is found.

[0022] Preferably, the deterministic planning model aims at economic optimization:

[0023]

[0024] Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; are decision variables for expansion, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, expansion is carried out, if the value is 0, no expansion is carried out; It is the decision variable for whether to configure distributed power generation. If the value is 1, it is configured; if the value is 0, it is not configured.

[0025] Preferably, the deterministic planning model includes: power grid operation constraints, natural gas grid constraints and equipment operation constraints.

[0026] Preferably, the flexibility operation verification model verifies whether the planning scheme is in a safe and stable operation area under the worst scenario. The worst scenario is the scenario where the RIES safety constraint is most likely to exceed the limit. The safety verification model takes maximizing the safety constraint offset as the objective function:

[0027]

[0028] Preferably, the flexibility requirement is that the probability of passing the RIES security constraint reaches 1-α,

[0029]

[0030] Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side, and α is the confidence level.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The planning method of the present invention fully considers the uncertainty in RIES, including the uncertainty in source, load and equipment, and effectively copes with the three types of uncertain fluctuations by improving the planning results through flexibility.

[0033] 2. The method of the present invention takes the operation phase into consideration during the planning process, relaxes the safety constraints of the operation phase, and effectively slows down the expansion investment by temporarily exceeding the limit.

[0034] 3. The bi-level programming model used in the method of the present invention is a mixed integer linear optimization model after mathematical processing, and is solved by using the C&CG algorithm without falling into the local optimal problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 Flowchart of planning method to improve flexibility of regional integrated energy system considering uncertainty;

[0037] Figure 2 Schematic diagram of the planning model for improving the flexibility of regional integrated energy systems considering uncertainty;

[0038] Figure 3 The RIES schematic diagram is composed of IEEE 33-node power distribution network and 11-node gas distribution network;

[0039] Figure 4 It is a schematic diagram of the initial electric load output curve;

[0040] Figure 5 It is a schematic diagram of the initial gas load output curve;

[0041] Figure 6 Schematic diagram of distributed power generation output curve. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0043] The present invention discloses a regional comprehensive energy system flexibility improvement planning method considering uncertainty, referring to Figure 1 and Figure 2 ,include:

[0044] -Establish a deterministic planning model and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model;

[0045] - Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme;

[0046] -Judge whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; if it does not meet the requirements, the upper-level planning scheme is changed until a scheme that meets the flexibility requirements in the worst scenario and is the most economical in non-bad scenarios is found.

[0047] The specific planning model is constructed as follows:

[0048] The deterministic planning model of regional integrated energy system aims at economic optimization:

[0049]

[0050] Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; Represents the vector form of decision variables; is the decision variable for whether the power grid line ij should be expanded, The decision variable for whether to expand the natural gas pipeline mn, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, then expand, if the value is 0, then do not expand; It is the decision variable for whether to configure distributed generation at grid node i. If the value is 1, it is configured; if the value is 0, it is not configured.

[0051] The deterministic planning model has three types of constraints, including power grid operation constraints, natural gas network constraints, and equipment operation constraints.

[0052] 1) Grid operation constraints:

[0053]

[0054] V min ≤V i,t ≤V max

[0055] in, is the power of the gas turbine installed at grid node i at time t; is the abandonment rate of the PV unit installed at grid node i at time t; is the wind curtailment rate of the wind turbine installed at grid node i at time t; P ji,tis the active power of the grid line section ji at time t; is the power of the power-to-gas equipment installed at grid node i at time t; V is the power delivered by RIES of grid node i to downstream user loads at time t; i,t is the node voltage of grid node i at time t; V0 is the nominal voltage of the grid; are the maximum values ​​of active power transmitted before and after the expansion of line ij; M is the larger value in the large M method; V min 、V max are the minimum and maximum values ​​of the node voltage.

[0056] 2) Natural gas network constraints:

[0057]

[0058]

[0059] in, are the inlet and outlet flow rates of the natural gas pipeline nm at time t respectively; is the natural gas flow rate generated by the power-to-gas unit installed at the natural gas network node m at time t; is the natural gas flow consumed by the gas boiler installed at the natural gas network node m at time t; is the injection flow of the natural gas source at the natural gas network node m at time t; is the natural gas flow delivered by RIES at natural gas network node m to downstream user loads at time t; is the average flow rate of natural gas pipeline nm at time t; is the coefficient before planning, D mn is the diameter of the natural gas pipeline nm, Δx mn is the length of the natural gas pipeline nm, F mn is the friction factor of the natural gas pipeline nm, R is the gas constant, T is degrees Fahrenheit, Z is the gas compression factor, ρ0 is the gas density; α′ is the coefficient after the natural gas pipeline is replaced; p m,t is the pressure of natural gas network node m at time t; is the average gas pressure of the natural gas pipeline nm at time t; is the initial coefficient of the natural gas pipeline; γ′ is the coefficient after the natural gas pipeline is replaced; L mn,t It is the storage of natural gas pipeline nm; are the minimum and maximum flow rates of the natural gas source output at the natural gas network node m, respectively; is the gas source ramp rate at natural gas network node m; p m,t is the pressure of natural gas network node m at time t; T fThe last scheduling moment of the day; L min Minimum pipeline storage of natural gas network.

[0060] 3) Equipment operation constraints

[0061]

[0062]

[0063] Among them, η g,i is the conversion efficiency of the gas turbine installed at grid node i; is the natural gas flow consumed by the gas turbine installed at grid node i at time t; H g is the calorific value of natural gas, taking 39MJ / m 3 ;P i G,min , P i G,max is the minimum and maximum technical output of the gas turbine installed at grid node i; is the start / stop flag of the gas turbine installed at grid node i at time t, 0 represents shutdown and 1 represents startup; is the upward and downward climbing rate of the gas turbine at the grid node i; η P2G,m is the conversion efficiency of the power-to-gas unit installed at the natural gas network node m; is the maximum power of the power-to-gas unit installed at natural gas network node m

[0064] The flexibility operation verification model needs to verify whether RIES is in a safe and stable operation area under the worst scenario. The worst scenario of RIES is the scenario where the safety constraints are more likely to exceed the limit, so the safety verification model uses the maximum safety constraint offset as the objective function.

[0065]

[0066] The constraints of the safety verification model include RIES safety operation constraints, power grid operation constraints considering the uncertainty of electric load and new energy output, natural gas grid operation constraints considering the uncertainty of gas load, and energy conversion equipment operation constraints considering the uncertainty of equipment. The power grid operation constraints, natural gas grid constraints, and equipment operation constraints have been described in the deterministic planning model, and now only the RIES safety operation constraints are described.

[0067] Considering that temporary violation of safety constraints will not affect the safe operation of RIES, this chapter sets the flexibility requirement as the probability of passing the RIES safety constraints reaching 1-α.

[0068]

[0069] Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side; α is the confidence level.

[0070] In summary, the two-level planning model of "economic planning + flexibility operation test" is as follows:

[0071]

[0072] st planning constraints (power grid, natural gas grid, equipment operation constraints)

[0073]

[0074] The present invention will be further described below in conjunction with specific embodiments.

[0075] This embodiment is used to expand the RIES consisting of IEEE 33-node distribution network and 11-node gas distribution network. The topology diagram is as follows: Figure 3 As shown, Figure 4-Figure 6 They are schematic diagrams of the initial electricity, gas load and distributed power generation output curves respectively.

[0076] like Figure 2 As shown, this embodiment includes: inputting example data, forming a RIES flexibility improvement planning model, iteratively solving, and outputting planning results.

[0077] The input calculation example data include: voltage level 12.66kV, controllable gas units connected at nodes 25 and 33, installed capacity of 1MW; uncontrollable photovoltaic units connected at node 22, installed capacity of 1MW; planning period of 20 years; safety constraint confidence coefficient α = 5%. Table 1 shows the corresponding parameters required by the planning method proposed in the present invention.

[0078] Table 1

[0079]

[0080]

[0081] Initial electricity, gas load and distributed generation output curves.

[0082] A planning model is formed according to the content of the invention, and the results after iterative solution are: power lines 1-2 2-3 6-73-23 23-24 6-26 26-27 are expanded, with an expansion cost of 19.3687 million yuan; natural gas pipelines 1-2 2-3 2-4 2-5 3-87-9 9-10 10-11 are expanded, with an expansion cost of 1.3521 million yuan. After the plan, photovoltaic consumption increases by 13.67%, and investment is reduced by 7.39%.

[0083] The present invention discloses a regional integrated energy system flexibility improvement planning system considering uncertainty, including the following modules

[0084] Module M1: Establish a deterministic planning model, and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model;

[0085] Module M2: Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme;

[0086] Module M3: Determine whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; if it does not meet the requirements, the upper-level planning scheme is changed until a scheme that meets the flexibility requirements in the worst scenario and has the best economic performance in non-bad scenarios is found.

[0087] The deterministic planning model aims at economic optimization:

[0088]

[0089] Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; Represents the vector form of decision variables; is the decision variable for whether the power grid line ij should be expanded, The decision variable for whether to expand the natural gas pipeline mn, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, then expand, if the value is 0, then do not expand; It is the decision variable for whether to configure distributed generation at grid node i. If the value is 1, it is configured; if the value is 0, it is not configured.

[0090] The deterministic planning model includes: power grid operation constraints, natural gas network constraints and equipment operation constraints.

[0091] The flexibility operation verification model verifies whether the planning scheme is in a safe and stable operation area under the worst scenario. The worst scenario is the scenario where the RIES safety constraint is most likely to exceed the limit. The safety verification model takes maximizing the safety constraint offset as the objective function:

[0092]

[0093] The flexibility requirement is that the probability of passing the RIES security constraint reaches 1-α,

[0094]

[0095] Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side, and α is the confidence level.

[0096] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0097] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0098] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for improving the flexibility of a regional integrated energy system, characterized in that: include: -Establish a deterministic planning model and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model; - Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme; - Determine whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; If the requirements are not met, the upper-level planning scheme is changed until a scheme is found that meets the flexibility requirements in the worst scenario and has the best economic efficiency in non-bad scenarios; The flexibility operation verification model verifies whether the planning scheme is in a safe and stable operation area under the worst scenario. The worst scenario is the scenario where the RIES safety constraint is most likely to exceed the limit. The safety verification model takes maximizing the safety constraint offset as the objective function: The flexibility requirement is that the probability of passing the RIES security constraint reaches 1-α, Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side, and α is the confidence level.

2. The method for improving the flexibility of a regional integrated energy system according to claim 1 is characterized in that: The deterministic planning model aims at economic optimization: Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; are decision variables for expansion, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, expansion is carried out, if the value is 0, no expansion is carried out; It is the decision variable for whether to configure distributed power generation. If the value is 1, it is configured; if the value is 0, it is not configured.

3. The method for improving the flexibility of a regional integrated energy system according to claim 2 is characterized in that: The deterministic planning model includes: power grid operation constraints, natural gas network constraints and equipment operation constraints.

4. A regional integrated energy system flexibility improvement planning system, characterized in that: Includes the following modules: Module M1: Establish a deterministic planning model, and input the planning scheme obtained by solving the model into the lower-level flexibility operation verification model; Module M2: Run the test model based on flexibility, consider the impact of uncertainty, and find the worst operating scenario under the planning scheme; Module M3: Determine whether the planning scheme meets the flexibility requirements in the worst scenario. If the safety constraints meet the requirements through probability, the planning scheme is directly output; if not, the upper-level planning scheme is changed until a scheme that meets the flexibility requirements in the worst scenario and is the most economical in non-bad scenarios is found; The flexibility operation verification model verifies whether the planning scheme is in a safe and stable operation area under the worst scenario. The worst scenario is the scenario where the RIES safety constraint is most likely to exceed the limit. The safety verification model takes maximizing the safety constraint offset as the objective function: The flexibility requirement is that the probability of passing the RIES security constraint reaches 1-α, Among them, P∈W is the probability distribution of uncertain variables on the energy side and the load side, and α is the confidence level.

5. The regional integrated energy system flexibility improvement planning system according to claim 4 is characterized by: The deterministic planning model aims at economic optimization: Among them, W I The equivalent annual value of the investment cost for RIES planning; W op is the annual operating cost of RIES; are decision variables for expansion, ij is the node number of the power grid, mn is the node number of the natural gas pipeline, E represents the power grid, N represents natural gas, if the value is 1, expansion is carried out, if the value is 0, no expansion is carried out; It is the decision variable for whether to configure distributed power generation. If the value is 1, it is configured; if the value is 0, it is not configured.

6. The regional integrated energy system flexibility improvement planning system according to claim 4 is characterized by: The deterministic planning model includes: power grid operation constraints, natural gas network constraints and equipment operation constraints.

Images