Microgrid multi-energy and carbon emission right trading method considering heterogeneity

Abstract

The application discloses a kind of micro-network multi-energy and carbon emission right transaction method in the field of power system regulation and power market, comprising the following steps: according to the different composition of internal equipment, multi-energy micro-network is divided into three types of industry, commerce, residents, and the model corresponding to each micro-network is established;On the basis of the established model, the overall transaction framework of the transaction of electricity, heat and carbon emission right between typical heterogeneous multi-energy micro-network is established;The network constraint of power grid is introduced in the transaction framework, to ensure that the actual transaction can be physically executed under the condition of distribution network safety, and finally a multi-micro-network coordination optimization mathematical model is established.The method of the application differentiates MEMG from equipment type and constructs representative equipment model, which is conducive to the full play of energy complementary potential between different types of multi-energy micro-network;A comprehensive and effective optimization framework and model are proposed to coordinate the electricity, heat and CER transaction activities between networked MEMG.

Description

Technical Field

[0001] This invention belongs to the field of power system regulation and power market, specifically relating to a method for trading multi-energy and carbon emission rights in microgrids that takes into account heterogeneity. Background Technology

[0002] Driven by energy security and environmental concerns, microgrids (MG), which integrate various types of distributed energy resources (DERs) such as distributed generators, flexible loads, and energy storage systems, are considered a promising future power system configuration due to their higher economic and environmental benefits compared to traditional modern power systems. Furthermore, research indicates that the comprehensive optimization of different energy carriers (such as electricity, heat, and natural gas) can yield more significant socio-economic, efficiency, and environmental benefits than a single electrical energy carrier. Therefore, multi-energy microgrids (MEMGs), which integrate energy production, conversion, storage, and consumption units of multiple energy forms, have received considerable attention in recent years.

[0003] Meanwhile, realizing the flexibility potential of DER is closely related to appropriate market participation. The energy trading market in the distribution network is a new market model that incentivizes interconnected MGs to flexibly trade energy, thereby making more coordinated and comprehensive use of DER flexibility and achieving local low-carbon sustainable development. Furthermore, introducing a carbon emission rights (CER) market in a deregulated market environment can enable local market participants (such as individual MGs) to proactively incorporate carbon emission reduction into their optimization strategies.

[0004] Currently, most studies on using market mechanisms to guide microgrids to participate in optimization do not construct an overall market for the simultaneous trading of electricity, heat, and CER (Consumer Energy Recycling). This is detrimental to fully realizing the multi-energy conversion potential of multi-energy microgrids and also discourages microgrids from spontaneously incorporating environmental benefits as part of their optimization goals. Furthermore, many studies fail to consider network constraints, which may lead to optimization results that violate grid network constraints (such as voltage or power flow limits), making physical energy trading impractical. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a microgrid multi-energy and carbon emission trading method that takes into account heterogeneity, in order to solve the problems mentioned in the background art.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for trading multi-energy and carbon emission rights in microgrids that takes into account heterogeneity includes the following steps: Based on the different internal equipment compositions, multi-energy microgrids are divided into three types: industrial, commercial, and residential, and a model corresponding to each type of microgrid is established. Based on the established model, an overall trading framework for trading electricity, heat, and carbon emission rights among typical heterogeneous multi-energy microgrids is established to fully tap the energy complementarity potential of multi-energy microgrids. By introducing power grid network constraints into the trading framework, the actual transactions can be physically executed under the premise of distribution network security, and finally, a mathematical model for multi-microgrid coordinated optimization is established.

[0007] Preferably, the multi-microgrid coordinated optimization mathematical model needs to take the minimum total cost of the microgrid as the optimization objective, calculate carbon emissions, and determine energy balance constraints, carbon market and multi-energy market trading constraints and network constraints.

[0008] Preferably, the energy balance constraints include electrical load balance constraints, thermal load balance constraints, and energy storage system constraints.

[0009] The beneficial effects of this invention are: 1. The method of the present invention distinguishes the heterogeneity of MEMGs by device type and constructs representative device models, which is conducive to giving full play to the energy complementarity potential between different types of multi-energy microgrids; 2. The method of this invention proposes a comprehensive and effective optimization framework and model to coordinate the electricity, heat and CER trading activities among networked MEMGs. This is the first time that the heterogeneity of MEMGs has been reflected in a holistic way, which can make fuller use of the flexibility of energy complementary regulation. At the same time, the integration of local multi-energy trading and CER trading helps to conduct comprehensive analysis from economic and environmental perspectives. 3. The method of this invention introduces power grid network constraints into the model, ensuring that energy trading can be carried out without violating network constraints, thus guaranteeing the safety of distribution network operation. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a diagram showing the device composition of three heterogeneous microgrids in an embodiment of the present invention; Figure 2 This is an overall framework diagram of electricity, heat, CER local transactions and network topology in an embodiment of the present invention; Figure 3 This is a topology diagram of the 4-MEMG system in an embodiment of the present invention; Figure 4 This is a price chart of buying / selling electricity, heat, and gas from the upstream market in an embodiment of the present invention; Figure 5 This is a comparison diagram of line power in an embodiment of the present invention; Figure 6 This is a comparison diagram of line voltage amplitude in an embodiment of the present invention. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] This embodiment provides a method for trading multi-energy and carbon emission rights in heterogeneous microgrids. Based on the different internal equipment compositions, multi-energy microgrids (MEMGs) are divided into three types: industrial, commercial, and residential, and a model is established for each type. On this basis, an overall trading framework for trading electricity, heat, and carbon emission rights (CERs) between typical heterogeneous MEMGs is established to fully explore the energy complementarity potential of MEMGs. Power grid constraints are introduced into the trading framework to ensure that actual transactions can be physically executed under the premise of distribution network security, and finally, a multi-microgrid coordinated optimization mathematical model is established.

[0014] The specific steps are as follows: Step 1: Based on the different internal equipment components, MEMGs are divided into the following three typical types (residential, commercial, and industrial), such as... Figure 1 As shown: Residential MEMGs typically install solar photovoltaic panels on the roof of their residences and micro-turbines (MTs) as backup generators. Gas boilers (GBs) are usually used to convert natural gas into heat to meet residential heating needs. Additional electric energy storage systems (ESSs) and heat storage systems (HSSs) are employed to store excess electricity and heat and release them at appropriate times to mitigate peak MEMG demand.

[0015] Commercial MEMGs: Since space heating is the primary source of heat demand for commercial MEMGs, they typically employ heat pumps (HP) capable of efficiently converting electrical energy into heat, with GB (Gas Heater) as a backup heat source. Aside from this, commercial MEMGs exhibit a similar configuration to residential MEMGs.

[0016] Industrial MEMGs: Combined Heat and Power (CHP) generators are commonly used in industrial MEMGs because they can simultaneously provide electricity and heat, improving energy efficiency. Power-to-Gas (P2G) and Carbon Capture Systems (CCS) can also be effectively combined with CHP. Since industrial parks are often located in open areas rich in wind energy resources, wind turbines (WT) are also frequently installed.

[0017] Step 2, establish as follows Figure 2 The overall framework for local electricity, heat, and CER trading in heterogeneous MEMGs is illustrated below, with relevant explanations: At the trading layer, MEMGs can directly buy / sell energy (in the form of electricity and heat) with other MEMGs in the trading market at local trading prices. They can also trade with upstream energy markets and CER markets. At the physical layer, heterogeneous MEMGs are distributed across different nodes of the distribution network and interconnected with the main grid.

[0018] To promote energy production and utilization and to assign and allocate carbon emission responsibility from the production side, each MEMG (Environmental, Energy, and Resources Group) needs to consume a certain number of CERs (Cost Emission Allowances) when purchasing fuel to produce electricity and heat, thus assuming responsibility for the carbon emissions generated during its production process. Each MEMG is initially allocated a certain number of free emission allowances, and MEMGs can also trade CERs on a local trading market. Specifically, if there are surplus CERs from the initial allocation, MEMGs can sell them to other MEMGs / upstream CER markets in the local area to obtain additional profits; conversely, if a MEMG engaged in production does not have enough CERs to sell its energy, it needs to purchase additional CERs locally to maintain the legality of its energy sales. Furthermore, if carbon emissions still exceed the limit when all CERs on the local market have been used or sold, the corresponding MEMG will be subject to emission penalties (requiring the purchase of additional CERs from the upstream market at a high price).

[0019] Step 3: Consider network constraints within the coordination framework to ensure the physical feasibility of energy trading decisions in MEMGs. Establish an overall model for local electricity, heat, and CER trading in heterogeneous multi-energy microgrids that includes network constraints. The specific implementation process is as follows: (1) The optimization objective is to minimize the total cost of the microgrid, as follows: In the formula, , , These represent the costs of purchasing electricity, heat, and natural gas for MG i at time t, respectively. This represents the cost of purchasing MG i and CER.

[0020] The cost calculation structure for electric heating and CER is similar. Taking the purchase cost of electricity as an example, the specific calculation process is as follows: In the formula, , This represents the amount of electricity that MG i buys / sells from MG j at time t. , This represents the unit price at which MGi buys / sells electricity from MGj at time t. This represents the amount of electricity that MG i buys / sells from the upstream market at time t. This represents the unit price at which MG i buys / sells electricity from the upstream market at time t.

[0021] Since the system is configured to allow the purchase or sale of natural gas only from the upstream market, the cost of natural gas is calculated as follows: In the formula, MG i The cost of natural gas at time t. and Let t represent the price and quantity (kW) of natural gas purchased from the upstream market at time t.

[0022] (2) Energy balance constraint Each microgrid needs to meet real-time energy balance constraints. Since multi-energy microgrids involve energy conversion and coupling, different types of equipment participate, generally categorized into real-time heat demand balance and real-time electricity demand balance. From an energy conversion perspective, the first category includes equipment that consumes natural gas to produce electricity or heat, as well as equipment that purchases electricity and heat from upstream sources for conversion (expressed as X1 in the following formula). The second category includes power-consuming equipment (such as Carbon Capture Systems (CCS) and P2G (expressed as Y1 in the following formula). The fourth category includes energy storage equipment. Electrical load balance constraints: In the formula, MG i exist t The power demand at any time Let X1 on MG i be the electrical energy output of device X1 at time t (including transformer, micro gas turbine, CHP, PV and WT). , They represent MG respectively i The discharge and charging power (kW) of the energy storage device at time t. For MG i The amount of electricity consumed by device Y1 at time t. , They represent MG respectively i Electricity (kW) purchased and sold to the upstream market at time t. , MG i At time t, to MG j Electricity purchased and sold (kW). The final electrical energy output of device X1 at time t is calculated by multiplying the imported energy by the corresponding conversion efficiency coefficient. The electricity consumed by device Y1 at time t is calculated by multiplying the output by the power consumption coefficient per unit. The result is obtained and the upper and lower limits of the device output are satisfied.

[0023] Heat load balance constraints: In the formula, MG i exist t The constant demand for thermal energy For MG i The thermal energy output of device X2 at time t (including heat exchanger, CHP and heat pump). , They represent MG respectively i The heat release and charge of the thermal storage equipment at time t (kW). , They represent MG respectively i The amount of heat (kW) purchased and sold from the upstream market at time t. , MG i At time t, to MG j Heat purchased and sold (kW). The final heat output of equipment X2 at time t is calculated by multiplying the imported energy by the corresponding conversion efficiency coefficient. The result is obtained and the upper and lower limits of the device output are satisfied.

[0024] In addition, energy storage systems need to meet the following constraints (the working principles of thermal storage systems and electrical storage systems are essentially the same; only the relevant formulas for electrical storage systems are listed here): In the formula, and Let represent the charge states of MGi at times t and t-1. and These represent the minimum and maximum storage states of the energy storage system. and Let represent the charging and discharging quantities (kW) of the energy storage system at time t in MG i, respectively. and The charging and discharging efficiencies (%) of the energy storage system in MG i are respectively. This refers to the maximum charge and discharge values ​​of the ESS. The 0-1 variables are used to control the charging and discharging states of the energy storage system.

[0025] (3) Calculation of carbon emissions In multi-energy microgrids, since carbon emissions are calculated from the power generation side, the calculation of carbon generation only involves three internal energy conversion devices (CHP, micro gas turbine, boiler, heat pump). However, in this invention, the carbon emissions from the CHP are directly captured on-site by the CCS device and transferred to the P2G device to generate natural gas. Therefore, the following carbon emission relationship is satisfied: In the formula, Let MGi be the carbon emissions (kg) of MGi at time t. MG i In the X3 device t Carbon emissions at any given moment. The carbon emission rate (kg / kWh) of device X3. For MG i The electrical or heat output of device X3 at time t. For MG i Carbon emissions (kg) of CHP at time t. and The carbon emission rate of CHP (kg / kWh). Let be the energy consumption of CHP at time t. Let t be the heat output of CHP. For MG iCarbon capture amount (kg) of CCS at time t. The carbon capture efficiency (%) of CCS. For MG i The amount of carbon received by the P2G at time t.

[0026] (4) Trading constraints in the carbon market and the multi-energy market for electricity and heat: The carbon market is set up as follows: In the formula, Let MGi be the carbon emissions (kg) of MGi at time t and The initial free carbon emission rights (kg) allocated to MG i and MG j. , These refer to the carbon emission rights purchased and sold by MG i to MG j, respectively. , These refer to the carbon emission rights that MG i purchases and sells to the upstream market.

[0027] Since the carbon market uses a 24-hour settlement system, while electricity and heat both use a 1-hour settlement system (with the same constraints; only the constraints for electricity trading are listed below), the corresponding constraints are as follows: In the formula, and These represent the electricity purchased and sold by MG i to MG j at time t, respectively. Indicates will cooperate with MG i Other multi-functional microgrids that conduct transactions and These refer to the carbon emission rights that MG i purchases and sells to MG j.

[0028] (5) Network constraints: In the formula, and Let be the active and reactive power on line (h, i) at time t, respectively. and Let be the active and reactive power injected at node i at time t. Let be the voltage (pu) at node h at time t. and Let be the resistance of line (h, i). and Minimum and maximum active power limits on the line, and These are the minimum and maximum voltage limits at the node, respectively. Let be the active power of line (i, j) at time t. and Represents a node. It is the set of all nodes on the line.

[0029] The verification of this embodiment is as follows: like Figure 3 As shown, a validation was conducted on a 4-MEMG system at the distribution network level, including two residential MEMGs (MG1 and MG4), one commercial MEMG (MG2), and one industrial MEMG (MG3). The device configurations and corresponding efficiencies of the three typical MEMGs are shown in Table 1 below.

[0030] Table 1 also, , , The purchase and sale prices in the upstream markets for electricity, heat, and CERs are as follows: Figure 4 As shown. The purchase price of CER from the upstream market is 0.4 yuan / kg, and the sale price of CER to the upstream market is 0.05 yuan / kg. The initial CER for each MEMG is 4 tons per day, the scheduling period is 24 hours, and real-time electricity and heat balance is achieved every hour. Carbon emission trading is set to settle once a day. The set value is 5%. , The values ​​are 0.001 and 0.001, respectively. The carbon emission coefficients of energy equipment and the carbon consumption coefficients of P2G are shown in Table 2 below.

[0031] Table 2 The following five scenarios were used for verification, and the results are shown in Table 3. The mathematical model was solved using the Python 3.8.11 platform in gurobipy 9.1.2.

[0032] Table 3 It is evident that the total cost of not trading electricity, heat, and CER between microgrids, or not trading electricity, heat, and CER simultaneously, is higher in both cost and carbon emissions than the setting of trading electricity, heat, and CER between microgrids. Specifically, when network constraints are considered, the total cost of not trading electricity, heat, and CER between microgrids is 9.32% higher than that of trading electricity, heat, and CER between microgrids. This is because trading local multi-energy and CER facilitates the flexibility of renewable energy release and is beneficial to environmental benefits, demonstrating that the proposed integrated framework has both economic and environmental value.

[0033] Meanwhile, with inter-microgrid trading of electricity, heat, and CER, although the total cost is lower without considering network constraints, this sacrifices grid security, making the optimization results impractical. Specific power and voltage pairings are as follows: Figure 5 and Figure 6 As shown. This verifies that the network constraint considerations introduced in this invention are beneficial to the security of the distribution network and the physical execution of transactions.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for trading multi-energy and carbon emission rights in microgrids that takes into account heterogeneity, characterized in that, Includes the following steps: Based on the different internal equipment compositions, multi-energy microgrids are divided into three types: industrial, commercial, and residential, and a model corresponding to each type of microgrid is established. Based on the established model, an overall trading framework for trading electricity, heat, and carbon emission rights among typical heterogeneous multi-energy microgrids is established to fully tap the energy complementarity potential of multi-energy microgrids. Introducing grid network constraints into the trading framework ensures that actual transactions can be physically executed under the premise of distribution network safety. Finally, a multi-microgrid coordinated optimization mathematical model is established. The multi-microgrid coordinated optimization mathematical model needs to calculate carbon emissions with the goal of minimizing the total cost of microgrids, and determine energy balance constraints, carbon market and multi-energy market trading constraints and network constraints. The optimization objective for minimizing the total cost of the microgrid is as follows: In the formula, , , These represent the costs of purchasing electricity, heat, and natural gas for MG i at time t, respectively. This represents the cost of purchasing MGi and CER; The cost of purchasing the electricity is calculated as follows: In the formula, , This represents the amount of electricity that MG i buys / sells from MG j at time t. , This represents the unit price at which MGi buys / sells electricity from MGj at time t. This represents the amount of electricity that MG i buys / sells from the upstream market at time t. This represents the unit price at which MG i buys / sells electricity from the upstream market at time t; The cost of the natural gas is calculated as follows: In the formula, MG i The cost of natural gas at time t. and These represent the price and quantity of natural gas purchased from the upstream market at time t, respectively. The energy balance constraints include electrical load balance constraints, thermal load balance constraints, and energy storage system constraints.

2. The microgrid multi-energy and carbon emission trading method considering heterogeneity according to claim 1, characterized in that, The electrical load balance constraint is: In the formula, MG i exist t The power demand at any time The electrical energy output of device X1 on MG i at time t, including the transformer, micro gas turbine, CHP, PV and WT. , They represent MG respectively i The discharge and charging capacity of the energy storage device at time t. For MG i The amount of electricity consumed by device Y1 at time t. , They represent MG respectively i The amount of electricity purchased and sold to the upstream market at time t. , MG i At time t, to MG j Electricity purchased and sold; The heat load balance constraint is: In the formula, MG i exist t The constant demand for thermal energy For MG i The thermal energy output of device X2 at time t, including the heat exchanger, CHP, and heat pump. , They represent MG respectively i The heat release and charge of the thermal storage equipment at time t. , They represent MG respectively i The amount of heat purchased and sold to the upstream market at time t. , MG i At time t, to MG j The amount of heat purchased and sold; The constraints of the energy storage system are: In the formula, and Let represent the charge states of MGi at times t and t-1. and These represent the minimum and maximum storage states of the energy storage system. and These represent the charging and discharging amounts of the energy storage system at time t in MGi, respectively. and These represent the charging and discharging efficiencies of the energy storage system in MG i. This refers to the maximum charge and discharge values ​​of the ESS. The 0-1 variables are used to control the charging and discharging states of the energy storage system.

3. The microgrid multi-energy and carbon emission trading method considering heterogeneity according to claim 1, characterized in that, The carbon emissions are calculated as follows: In the formula, Let be the carbon emissions of MG i at time t. MG i In the X3 device t Carbon emissions at any given moment. The carbon emission rate of device X3. For MG i The electrical or heat output of device X3 at time t; For MG i Carbon emissions of CHP at time t. and The carbon emission rate of CHP. Let be the energy consumption of CHP at time t. Let t be the heat output of CHP; For MG i Carbon capture amount of CCS at time t For the carbon capture efficiency of CCS, For MG i The amount of carbon received by the P2G at time t.

4. The microgrid multi-energy and carbon emission trading method considering heterogeneity according to claim 1, characterized in that, The carbon market trading constraints are as follows: In the formula, Let be the carbon emissions of MG i at time t. and The initial free carbon emission rights allocated to MG i and MG j , These refer to the carbon emission rights purchased and sold by MG i to MG j, respectively. , These refer to the carbon emission rights that MG i purchases and sells to the upstream market. The trading constraints of the aforementioned multi-energy electric heating market are: In the formula, and These represent the electricity purchased and sold by MG i to MG j at time t, respectively. Indicates will cooperate with MG i Other multi-functional microgrids that conduct transactions, and These refer to the carbon emission rights that MG i purchases and sells to MG j.

5. The microgrid multi-energy and carbon emission trading method considering heterogeneity according to claim 1, characterized in that, The network constraints are: In the formula, and Let be the active and reactive power on line (h, i) at time t, respectively. and Let be the active and reactive power injected at node i at time t. Let be the voltage at node h at time t. and Let be the resistance of line (h, i); and Minimum and maximum active power limits on the line, and These are the minimum and maximum voltage limits at the node, respectively. Let be the active power of line (i, j) at time t. and Represents a node. It is the set of all nodes on the line.

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