Plant-level thermoelectric integrated energy system robust optimization method

Abstract

The invention discloses a robust optimization method for a plant-level thermoelectric integrated energy system. The method comprises the following steps: 1, calculating the economical efficiency of a cogeneration unit when no wind power and photovoltaic access exists in an electric-thermal integrated energy system; 2, calculating the economical efficiency when the wind power and the photovoltaic participate in undertaking the electric heating load in the electric-thermal comprehensive energy system; 3, calculating a decoupling load capacity after wind power and photovoltaic power are added into the electric-thermal comprehensive energy system; 4, calculating a probability density economic function of the load capable of being decoupled; 5, constructing an overall optimization objective function and solving constraint conditions of the electric-thermal integrated energy system; and step 6, solving the objective function by using a KRO robust optimization algorithm to obtain an optimal scheduling strategy of the electric-thermal integrated energy system. According to the method, wind power and photovoltaic power are introduced into the heat supply network of the system to cooperate with a thermal-electric decoupling integrated energy system robust optimization scheduling strategy, so that the system robustness is improved, and meanwhile, the wind and light absorption capability of the system is improved to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the field of optimization and scheduling of integrated energy systems with multi-energy complementarity, and relates to a source-load coordination matching method in a thermal-electric integrated energy system, and specifically to an optimization and scheduling method for an electric-thermal integrated energy system based on decoupling electric quantity and electric quantity transfer ratio as relaxation factors and using a KRO robust optimization algorithm. Background Art

[0002] With the proposal and development of new power systems, the proportion of new energy generation represented by wind power and photovoltaic power in the power system has gradually increased. How to absorb new energy generation and reduce the impact of its volatility on the stability of the power system is an important research direction. At present, the most common method is to use the AGC regulation optimization technology of thermal power coal-fired units, combined with unit transformation technologies such as deep peak regulation technology, high back pressure transformation and cylinder cutting operation transformation to achieve the improvement of the coordinated system performance of thermal power units. However, with the needs of social production development, three basic problems have emerged in the field of energy systems: First, with the continuous increase in the proportion of new energy generation, the automatic control regulation of thermal power units can no longer fully absorb all new energy generation; secondly, the absorption of new energy through deep peak regulation and cylinder cutting operation of a single thermal power unit will seriously damage the economic operation of the system; finally, the "heat-to-electricity" operation mode of cogeneration units to a certain extent limits the absorption of new energy in the power system. Although there are engineering examples of absorbing excess new energy by building energy storage power stations, due to the large initial investment, high maintenance costs and limited service life of energy storage, it has not been put into use nationwide. Therefore, how to avoid the "heat-based electricity" operation mode of cogeneration units, eliminate the electric-thermal coupling relationship in the electric-thermal integrated energy system, thereby releasing the power supply share of thermal power units in the power system, and then improving the wind and solar power absorption capacity in the integrated energy system and improving the system's operating economy is one of the important directions for optimizing the scheduling of the integrated energy system.

[0003] At present, the heat source in the integrated energy system mainly comes from thermal power units. When new energy can realize the conversion of energy forms through energy conversion equipment such as electric boilers and heat pumps and connect it in parallel with the heating network connected to the cogeneration unit, the difference between the online power supply given by the grid dispatching instruction and the actual power generation of new energy power can be used to obtain the decoupled load of new energy in the electric and thermal integrated energy system. Combined with the conversion efficiency of the energy conversion equipment, the replacement ratio of new energy power generation and the heating supply of the cogeneration unit, that is, the decoupled power transfer ratio, can be calculated. Summary of the invention

[0004] The present invention provides a robust optimization method for a plant-level thermal power integrated energy system. The method uses the KRO robust optimization algorithm to optimize the scheduling of the electric-thermal integrated energy system based on the load ΔP of the electric-thermal integrated energy system replaced by new energy and the decoupled power transfer ratio coefficient ξ. In the electric-thermal integrated energy system mainly based on the cogeneration unit, the present invention introduces wind power and photovoltaic power as additional power sources to decouple the electric-thermal load of the cogeneration unit, and uses wind power and photovoltaic power to participate in the system heating through electric-thermal conversion through electric boilers, thereby reducing the online power of the cogeneration unit, increasing the wind and solar power absorption capacity of the system, and obtaining the most economical scheduling strategy of the system through the KRO robust optimization scheduling method to improve the robustness of the system.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A robust optimization method for plant-level thermal power integrated energy system first calculates the decoupled load between the cogeneration unit and the wind and solar power source; then, on this basis, introduces the decoupled power transfer ratio coefficient and calculates the probability density function of the overall economic efficiency of the transferred load; then, establishes the overall optimization objective function and gives the constraints of the system composition; finally, solves it through the KRO robust optimization scheduling algorithm to obtain the optimal scheduling instructions of the system. Specifically, it includes the following steps:

[0007] Step 1: Calculate the economic efficiency of the combined heat and power unit in the electric-thermal integrated energy system without wind power and photovoltaic access M =P N (M p -H N M r )+Q N (M q -H h M r ), M p is the on-grid electricity price, M q is the heating price, M r is the standard coal price, P N is the CHP power generation load, Q N is the CHP heating load, H N is the heat consumption of power generation, H h Heat consumption for heating;

[0008] Step 2: Calculate the economic benefits of wind power and photovoltaic power participating in the electric-thermal integrated energy system W =((P W -P r )+(P v -P c ))M p +(P r +P c )ηd M q -W s , P r is the photovoltaic transfer load, P c is the wind power transfer load, P v is the total photovoltaic load, P W is the total wind power load, η d is the conversion efficiency of the electric boiler, W s is the cost conversion rate;

[0009] Step 3: Calculate the decoupled load ΔP after adding wind power and photovoltaic power to the electric-thermal integrated energy system;

[0010] Step 4: Calculate the probability density economic function J of the decoupled load Z =f(ξ|ΔP), ξ is the wind power consumption transfer ratio coefficient;

[0011] Step 5: Construct the overall optimization objective function of the electric-thermal integrated energy system and solve the constraint conditions J = (P N H N M r +Q N H h M r )-[((P W -P r )+(P v -P c ))M p +(P r +P c )η d M q -W s ]-f(ξ|ΔP);

[0012] Step 6. Use the KRO robust optimization algorithm to solve the objective function, use ΔP and ξ as relaxation factors to transform the nonlinear programming problem into a linear programming problem, and solve it to obtain the optimal scheduling strategy of the electric-thermal integrated energy system.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1) By connecting wind power and photovoltaic power to the electric and thermal integrated energy system with cogeneration units as the main body, the coupling relationship between electric and thermal loads can be solved, the online power of thermal power units can be reduced, thereby increasing the consumption of new energy and reducing the low-load operation and shutdown of pure condensing units;

[0015] 2) Distributing the system's electric and thermal loads through multiple power sources can ensure the system's energy supply and quality;

[0016] 3) The economic expected value of the transferred electricity is calculated using the probability density function, which further simplifies the nonlinear robust optimization problem and improves the system robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the principle diagram of robust optimization scheduling of plant-level thermal power integrated energy system;

[0018] Figure 2 It is the energy flow schematic diagram of the plant-level integrated energy system. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0020] By introducing wind power and photovoltaic power into the electric-thermal integrated energy system to decouple heat and electricity, it is helpful to absorb new energy in the system and improve the robustness of the system. The present invention provides a robust optimization method for a plant-level thermal-electric integrated energy system based on a plant-level electric-thermal integrated energy system based on a cogeneration unit, and introduces wind power and photovoltaic power into the system heating network to cooperate with the robust optimization scheduling strategy of the thermal-electric decoupled integrated energy system, thereby improving the robustness of the system and increasing the wind and solar absorption capacity of the system to a certain extent. Figure 1 and Figure 2 As shown, the method comprises the following steps:

[0021] Step 1: Calculate the economic efficiency of the combined heat and power unit in the electric-thermal integrated energy system without wind power and photovoltaic access M =P N (M p -H N M r )+Q N (M q -H h M r ), M p is the on-grid electricity price, M q is the heating price, M r is the standard coal price, P N is the CHP power generation load, Q N is the CHP heating load, H N is the standard coal consumption for power generation, H h It is the standard coal consumption for heating.

[0022] This step is achieved by calculating the power supply heat consumption and heating heat consumption of the thermal power unit respectively, and converting the heat consumption into a unified standard coal consumption H N , H h , economic calculation is carried out through coal consumption.

[0023] Step 2: Calculate the economic benefits of wind power and photovoltaic power participating in the electric-thermal integrated energy system W =((P W -P r )+(P v -P c ))M p +(P r +P c )η d M q -W s , P r is the photovoltaic transfer load, P c is the wind power transfer load, P v is the total photovoltaic load, P W is the total wind power load, η d is the conversion efficiency of the electric boiler, W s is the comprehensive cost impairment rate.

[0024] This step is achieved by calculating the total load of wind power and photovoltaic power and their respective power generation transfer loads, and calculating their power supply revenue and heat supply revenue respectively. In addition, new energy also supplies the plant power load in the system.

[0025] Step 3: Calculate the decoupled load ΔP after adding wind power and photovoltaic power to the electric-thermal integrated energy system.

[0026] This step is achieved by calculating the difference between the photovoltaic and wind power grid-connected power in the grid dispatching instructions and the actual photovoltaic and wind power generation to obtain the decoupled load power of the new energy in the system.

[0027] Step 4: Calculate the probability density economic function J of the decoupled load Z =f(ξ|ΔP), ξ is the wind power consumption transfer ratio coefficient.

[0028] This step is achieved by adjusting ξ the ratio of ΔP between absorbing new energy and ensuring the operation of pure condensing units. The wind power absorption transfer ratio coefficient belongs to the interval [0,1]. When it is 0, ΔP is completely transferred to the power grid and participates in the load distribution of pure condensing units. The probability density function is calculated based on this and economic benefits are obtained. If it is 1, this part of electricity is completely used to absorb wind power on the grid, and its economic calculation is based on the on-grid electricity price when the maximum wind power is absorbed.

[0029] Step 5: Construct the overall optimization objective function of the electric-thermal integrated energy system and solve the constraint conditions J = (P N H N M r +Q N H h M r)-[((P W -P r )+(P v -P c ))M p +(P r +P c )η d M q -W s ]-f(ξ|ΔP).

[0030] This step is achieved by synthesizing the sub-function calculations of the previous four steps to obtain the final objective function, which mainly includes the total cost of the electric load and thermal load of the cogeneration unit, the total income of wind power generation, solar power generation and electric-thermal conversion, and the wind and solar energy transfer load density economic function. The constraints include electric-thermal coupling output constraints, heat network constraints, power balance constraints and unit processing constraints.

[0031] Step 6. Use the KRO robust optimization algorithm to solve the objective function, use ΔP and ξ as relaxation factors to transform the nonlinear programming problem into a linear programming problem, and solve it to obtain the optimal scheduling strategy of the electric-thermal integrated energy system.

[0032] This step is achieved by controlling the fluctuation range of random variables through KRO robust optimization, thereby coordinating the optimality and robustness of the optimization result. In the present invention, ΔP is used as the constraint decision variable of the objective function. When f(ΔP)=0, simple robust optimization is completed without considering ΔP to obtain the thermal power load distribution ratio. When f(ΔP)≠0, the relaxation factor is non-zero, and robust optimization is used again for calculation, and the relaxation factor is used as a constraint to complete the optimization constraint calculation.

Claims

1. A robust optimization method for a plant-level thermal power integrated energy system, characterized in that The method comprises the following steps: Step 1: Calculate the economic efficiency of the combined heat and power unit in the electric-thermal integrated energy system without wind power and photovoltaic access M =P N (M p -H N M r )+Q N (M q -H h M r ), M p is the on-grid electricity price, M q is the heating price, M r is the standard coal price, P N is the CHP power generation load, Q N is the CHP heating load, H N is the heat consumption of power generation, H h Heat consumption for heating; Step 2: Calculate the economic benefits of wind power and photovoltaic power participating in the electric-thermal integrated energy system W =((P W -P r )+(P v -P c ))M p +(P r +P c )η d M q -W s , P r is the photovoltaic transfer load, P c is the wind power transfer load, P v is the total photovoltaic load, P W is the total wind power load, η d is the conversion efficiency of the electric boiler, W s is the comprehensive cost impairment rate; Step 3: Calculate the decoupled load ΔP after adding wind power and photovoltaic power to the electric-thermal integrated energy system; Step 4: Calculate the probability density economic function J of the decoupled load Z =f(ξΔP), ξ is the wind power consumption transfer ratio coefficient; Step 5: Construct the overall optimization objective function of the electric-thermal integrated energy system and solve the constraint conditions J = (P N H N M r +Q N H h M r )-[((P W -P r )+(P v -P c ))M p +(P r +P c )η d M q -W s ]-f(ξΔP); Step 6. Use the KRO robust optimization algorithm to solve the objective function, use ΔP and ξ as relaxation factors to transform the nonlinear programming problem into a linear programming problem, and solve it to obtain the optimal scheduling strategy of the electric-thermal integrated energy system.

2. The robust optimization method for a plant-level thermal power integrated energy system according to claim 1 is characterized in that In the step three, the decoupled load power is calculated by calculating the difference between the photovoltaic and wind power grid-connected power in the grid dispatching instruction and the actual photovoltaic and wind power generation.

3. The robust optimization method for a plant-level thermal power integrated energy system according to claim 1 is characterized in that In the step 4, the ratio of ΔP between absorbing new energy and ensuring the operation of pure condensing units is adjusted by ξ. The wind power absorption transfer ratio coefficient belongs to the interval [0,1]. When it is 0, ΔP is completely transferred to the power grid and participates in the load distribution of pure condensing units. The probability density function is calculated to obtain economic benefits. If it is 1, this part of electricity is completely used to absorb wind power on the grid, and its economic calculation is based on the grid-connected electricity price when the maximum wind power is absorbed.

4. The robust optimization method for a plant-level thermal power integrated energy system according to claim 1 is characterized in that In the step five, the constraints include electric-thermal coupling output constraints, thermal network constraints, power balance constraints and unit processing constraints.

5. The robust optimization method for plant-level thermal power integrated energy system according to claim 1 is characterized in that In the step six, ΔP is used as the constraint decision variable of the objective function. When f(ΔP)=0, simple robust optimization is performed without considering ΔP to obtain the thermal power load distribution ratio. When f(ΔP)≠0, the relaxation factor is non-zero, and robust optimization is used again for calculation, and the relaxation factor is used as a constraint to complete the optimization constraint calculation.

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