Indirect calculation method of exergy flow in integrated energy system based on unbalanced node power

Abstract

The present invention discloses an indirect calculation method for the flow of an integrated energy system based on unbalanced node power, comprising: under the condition of known unbalanced node power, constructing an indirect calculation model for the flow of a thermal system based on a flow mechanism model of a thermal system; constructing an indirect calculation model for the flow of an electric power system based on a flow mechanism model of an electric power system; constructing an indirect calculation model for the flow of a natural gas system based on a flow mechanism model of a natural gas system; constructing an indirect calculation model for the flow of an energy station based on a flow mechanism model of an energy station; establishing an indirect calculation model for the flow of an integrated energy system based on unbalanced node power; solving the flow distribution of the thermal system, solving the flow distribution of the electric power system, solving the flow distribution of the natural gas system, and solving the equivalent node loss of each energy station; and finally forming the overall flow and node potential distribution of the integrated energy system.

Description

Technical Field

[0001] The present invention relates to the field of integrated energy systems, energy system effective energy and energy quality analysis, and in particular to integrated energy systems under known unbalanced node power conditions. Stream indirect calculation method. Background Art

[0002] In order to solve the increasingly severe environmental problems, my country has put forward the goal of "carbon peak and carbon neutrality". As the focus of carbon emissions, the energy sector is imperative to promote energy transformation and build a clean, efficient and sustainable energy system. While meeting the energy supply of diversified loads, the integrated energy system (IES) reduces losses and improves energy efficiency through multi-energy complementarity, thereby achieving the goal of energy conservation and emission reduction. Therefore, building an efficient and high-quality IES is an important measure to solve the current problems of environmental pollution and resource shortages.

[0003] At present, most of the related research is based on the establishment of IES model at the energy level. Some studies have proposed gas, water and heat circuit models, established a unified energy circuit theory, and studied the optimal scheduling of the electric-gas-heat interconnected system from the perspective of energy; some studies have modeled IES through energy balance, and proposed a two-stage optimization method for the coupling problem of capacity planning and operation; some studies have proposed an IES event-triggered online energy flow control strategy based on Lyapunov optimization. The above studies all focus on system energy and analyze the energy interaction between different energy systems based on the energy hub model.

[0004] Typical IES usually involve networked energy systems of electricity, natural gas, and heat. Traditional energy flow research mainly focuses on the "quantity" of energy, but does not consider the differences in the "quality" of different energies. For example, it is generally believed that the quality of electric energy is higher than that of thermal energy. As a physical quantity to measure the quality of energy, it takes into account both the "quantity" and "quality" of energy and is introduced into the research of energy systems. Some studies have studied the energy conversion process of dual-gas-head polygeneration systems, geothermal power plants, and grid-connected underwater compressed air energy storage. The above literature is about Most of the research focuses on the specific energy conversion process of power generation and heat generation. Some studies also regard IES as a black box model. Efficiency is used as an indicator to evaluate the development and construction of IES. Efficiency is introduced as the objective function in the planning and optimization scheduling of IES; some studies are based on The IES comprehensive energy efficiency evaluation method considering energy quality was proposed. Change analysis or The efficiency studies have not considered the network properties of IES. Some studies have established Theory of pipeline transfer analysis in energy networks, but no attention is paid to The distribution in the energy network, that is, the characteristic of "flow".

[0005] At present, some scholars have tried to combine energy, carbon emissions, and information variables with the network properties of IES to establish energy flow, carbon flow, and information flow models. Therefore, the integrated energy system with network characteristics also requires an energy quality analysis theory based on "flow". Therefore, it is necessary to study the different links of the integrated energy system. Flow calculation method to establish a comprehensive energy system under the condition of known unbalanced node power The flow computing model aims to provide a convenient and efficient analysis tool for the energy quality characteristics analysis of the integrated energy system. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a comprehensive energy system based on unbalanced node power. Stream indirect calculation method.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] An integrated energy system based on unbalanced node power Stream indirect calculation methods, including:

[0009] S1. Under the condition that the supply node temperature, return node temperature, outlet node temperature and water flow rate of the thermal system are known, based on the thermal system Flow mechanism model, calculate the thermal nodes Potential, construct node-branch association matrix to describe the two ends of the pipeline Potential difference, construct outflow node-branch association matrix to describe the pipeline head end Potential, and then establish a thermal system based on water flow distribution Stream indirect computation model;

[0010] S2. Under the condition of known power flow of power system, based on power system flow mechanism model, establish active power and The connection of the flow, calculate the power node trend, and then establish a power system based on power flow distribution Stream indirect computation model;

[0011] S3. Under the condition that the natural gas flow rate of the natural gas system is known, based on the natural gas system Flow mechanism model, calculate the natural gas node potential, and then establish a natural gas system based on gas flow distribution Stream indirect computation model;

[0012] S4, based on energy station Flow mechanism model, establish energy station corresponding to electricity, natural gas and heat connection nodes Flow, with nodes Loss indicates energy station Flow, and then establish an energy station based on equivalent nodes Stream indirect computation model;

[0013] S5. Combined with thermal system based on water flow distribution Flow indirect calculation model, power system based on flow distribution Flow indirect calculation model, natural gas system based on gas flow distribution Flow indirect calculation model, energy station based on equivalent nodes Flow indirect calculation model, establish a comprehensive energy system based on unbalanced node power Stream indirect computation model;

[0014] S6. Based on the unbalanced node power, select the multi-energy flow calculation model to solve the power flow, natural gas flow rate, water supply node temperature, return node temperature, outlet node temperature and water flow rate of the comprehensive energy system;

[0015] Based on the supply node temperature, return node temperature and outlet node temperature of the thermal system, solve the supply node, return node and outlet node temperature Potential, combined with the water flow rate results, using a thermal system based on water flow distribution Flow indirect calculation model to solve the thermal system Flow distribution;

[0016] Based on the power flow results, a power system based on power flow distribution is adopted Flow indirect calculation model to solve the power system Flow distribution;

[0017] Based on the calculation results of natural gas flow rate and natural gas nodes The natural gas system based on gas flow distribution Flow indirect calculation model to solve the natural gas system Flow distribution;

[0018] Based on energy stations corresponding to electricity, natural gas and heat connection nodes Flow, using energy stations based on equivalent nodes Flow indirect calculation model to obtain equivalent nodes of each energy station damage;

[0019] Finally, a comprehensive energy system is formed Streams and Nodes Potential distribution.

[0020] Furthermore, in step S1:

[0021] When the heat load is known, the pipeline water flow rate and the water temperature of the supply, return and outlet nodes are calculated based on the thermal flow calculation to obtain the temperature of each node. potential, based on Potential and flow rate solution Flow Loss distribution; according to the water temperature T at the node, the ambient temperature T a , defining the nodes of the thermal system Potential T for:

[0022] p T =(TT a lnT-T a +T a oeLh a )c p (30)

[0023] Where: c p is the specific heat capacity of water; node Potential T Reflects the unit water flow rate node Potential difference Δp T Reflects the heat transferred per unit water flow rate

[0024] According to the node Potential and water flow rate, calculation elements Flow and components transfer heat Among them, the components Flow The product of potential and water flow rate, the heat transferred by the element for The product of potential difference and water flow rate:

[0025]

[0026] Where: e h For components flow;m h is the water flow rate; p T Nodes connected to the component Potential; Δe h Transfer heat to components include Loss and heat source load ΔpT The nodes at both ends of the component potential difference;

[0027] For large-scale thermal systems, the heat source transfers heat For water supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as:

[0028] Δe h,S =diag(p s -p r )m h,S (32)

[0029] Where: Δe h,S For heat source Column vector; diag(·) represents a diagonal matrix consisting of the elements in the vector; p s and p r They are respectively the supply and return nodes Potential column vector; m h,S is the heat source water flow rate column vector. When the i-th node is the heat source water supply node, m h,S The i-th element of is the water flow rate of this node, and the other elements are 0; the water flow direction from the supply water to the return water node is selected as positive, m h,S and Δe h,S The non-zero elements of are negative;

[0030] Similarly, the load transfers heat Represented as supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as:

[0031] Δe h,L =diag(p s -p o )m h,L (33)

[0032] Where: Δe h,L For load Column vector; p o For the exit node Potential column vector; m h,L is the load water flow rate column vector. When the i-th node is a load water supply node, m h,L The i-th element of is the water flow rate of this node, and the other elements are 0; m h,L and Δe h,L Non-zero elements are positive values;

[0033] In thermal systems, some load outlet nodes Potential and Return Nodes There is a difference in potential, which generates load Loss, this part Loss is represented by outlet and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as:

[0034] Δe h,Ll =diag(p o -p r )m h,L (34)

[0035] Where: Δe h,Ll For load Loss column vector;

[0036] The node-branch association matrix is ​​used to describe the thermal system topology. For a large-scale thermal system, the nodes at both ends of the water supply pipe are The potential difference is determined by the node-branch association matrix and the node The potential vector represents the water supply pipeline The loss is expressed as:

[0037]

[0038] Where: Δe h,s For water supply pipes Loss vector, n h,p is the number of water supply pipes; m h is the water flow rate column vector of the water supply pipeline; T represents the transpose of the matrix; A h is the node-branch association matrix of the water supply network;

[0039] Assuming that the supply network and the return network are completely symmetrical and that water flow losses are ignored, the node-branch association matrix of the return network is considered to be -A h ; Similarly, the return pipe Loss vector Δe h,r It is expressed as:

[0040]

[0041] Based on thermal system Flow Mechanism Model, Pipeline The flow is mainly composed of water flowing out of the node in the pipe. The outflow node-branch association matrix and the inflow node-branch association matrix of the water supply network are defined to characterize the topological relationship between the branches and the outflow and inflow nodes;

[0042] Among them, the water supply network outflow node-branch association matrix A h,- The elements in are represented as:

[0043]

[0044] Where: (i, j) represents the element in the i-th row and j-th column of the matrix;

[0045] Affected by the symmetry of the water supply and return network, the water supply network inflow node-branch association matrix A h,+ That is, the outflow node-branch association matrix of the backwater network, whose elements are:

[0046]

[0047] A h,- For-A h The matrix A is composed of 1 h,+ A h The matrix composed of 1 in , and satisfies:

[0048] A h =-A h,- +A h,+ (39)

[0049] Based on the above association matrix, node Potential column vector, water flow rate column vector of water supply pipe, and matrix form to represent water supply and return pipes respectively flow:

[0050]

[0051] Where: e h,s and e h,r Water supply and return pipes Flow column vector;

[0052] Based on the thermal flow, the water flow rate of the water supply network and the water temperature of each node are solved to construct the water supply, return water and outlet nodes Potential vector, using equations (3)-(12) to solve the large-scale thermal system Flow distribution.

[0053] Furthermore, in step S2:

[0054] line flow, Loss and source load Expressed as a vector:

[0055]

[0056] Where: e e , Δe e , P e and ΔP e Power system flow, loss, transmission active power and active power loss column vector; e e,N and P e,NPower source and load The power column vector of the power source and load, the corresponding elements of the load are positive, the corresponding elements of the power source are negative, and the corresponding elements of the connection node are 0;

[0057] Under the condition of known unbalanced node power, the active power flow distribution can be solved by using algorithms such as the Newton method, PQ decomposition method or forward-backward substitution method to obtain the power system The current distribution and active power loss are The voltage is the power system Momentum.

[0058] Furthermore, in step S3:

[0059] The steady-state analysis of natural gas network takes the non-equilibrium node gas flow rate as a known quantity to represent the power provided by the gas source or consumed by the load; the pipeline gas flow rate distribution is solved based on the energy flow of the natural gas system, and the gas flow rate of each natural gas node is obtained. potential, and thus obtain the natural gas system Flow distribution, gas nodes Potential g It is expressed as:

[0060]

[0061] Where: T b is the theoretical combustion temperature of natural gas; G is the calorific value of natural gas; ambient temperature T a ;

[0062] Considering the large-scale natural gas system, the natural gas system The stream indirect computation model is expressed as:

[0063]

[0064] Where: e g and m g Natural gas pipeline Flow and airflow rate column vector; e g,N and m g,N Natural gas source load and the airflow rate vector.

[0065] Further, in step S4:

[0066] The energy station is equivalent to the integration of electricity, natural gas and heat nodes. The flow indirect calculation model obtains the equivalent nodes of the energy station flow, the energy station is equivalent to Damaged nodes are represented by vectors. damage:

[0067] eEH,l =e EH,e +e EH,g +e EH,h (45)

[0068] Where: e EH,l Energy station node Loss column vector; e EH,e 、e EH,g and e EH,h They are the nodes corresponding to electricity, natural gas and heat in the energy station. Flow column vector, if the i-th energy station has no connected node of the k-th energy form, then e EH,k The i-th element is 0, as shown below:

[0069] e EH,k (i,1)=0, k∈[e,g,h] (46)

[0070] Further, in step S5,

[0071] 1) Based on the unbalanced node power, network topology, pipeline parameters, energy station equipment model and operation mode data, a multi-energy flow calculation model is selected to solve the power flow, natural gas flow rate, water supply node temperature, return water node temperature, outlet node temperature and water flow rate of the comprehensive energy system;

[0072] 2) Obtain the power system nodes through the voltage in the power system The power system is obtained by the power flow distribution and power source and load power in the power system. Flow distribution, power systems Flow distribution includes flow and harmony Loss and source load

[0073] 3) By gas node The potential and natural gas flow rate are used to obtain the natural gas system Flow distribution, natural gas systems Flow distribution including natural gas pipelines Flow and natural gas source load

[0074] 4) Obtain the temperature of the water supply node, return water node and outlet node according to the temperature of each node in the thermal system potential, through each node Potential and water flow rate to solve the thermal system Flow distribution, thermal system Flow distribution includes various elements flow, Loss, load and heat source

[0075] 5) Based on the energy station corresponding to the electricity, natural gas and heat connection nodes Flow, obtain the equivalent nodes of each energy station damage;

[0076] 6) Forming an integrated energy system Streams and Nodes Potential distribution.

[0077] The present invention also provides a comprehensive energy system based on unbalanced node power A stream indirect computing device, comprising:

[0078] Thermal system Flow indirect calculation unit, used to calculate the thermal system Flow mechanism model establishment based on water flow distribution thermal system Stream indirect computation model;

[0079] Power System Flow indirect calculation unit, used to calculate the power system Flow mechanism model establishment based on power system flow distribution Stream indirect computation model;

[0080] Natural gas system Flow indirect calculation unit for natural gas systems Flow Mechanism Modeling for Natural Gas Systems Stream indirect computation model;

[0081] Energy Station Flow indirect calculation unit for energy stations Flow mechanism model to establish energy station Stream indirect computation model;

[0082] Integrated Energy Systems Flow indirect calculation unit, used to calculate the power system Flow indirect calculation model, natural gas system Flow indirect computing model, energy station Flow indirect calculation model to solve the thermal system Flow distribution, power system Flow distribution, natural gas systems Flow distribution and equivalent nodes of each energy station loss, and finally obtain the overall integrated energy system Streams and Nodes Potential distribution.

[0083] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the integrated energy system based on unbalanced node power when executing the program. Steps of the flow indirect calculation method.

[0084] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements an integrated energy system based on unbalanced node power. Steps of the flow indirect calculation method.

[0085] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0086] 1. Compared with the research on medium flow and energy flow of traditional integrated energy system, The flow comprehensively considers the "quantity" and "quality" of energy and adopts a comprehensive energy system based on unbalanced node power. The flow indirect calculation method can effectively solve the system Flow distribution, That is, effective energy, based on Flow distribution can realize the coordinated analysis of the "quantity" and "quality" of the integrated energy system.

[0087] 2. Given the non-equilibrium node thermal power, the thermal system flow calculation model is used to solve the supply node temperature, return node temperature, outlet node temperature and water flow rate, and then the thermal system based on water flow distribution is used. Flow indirect calculation model to solve the thermal system Flow distribution enables energy quality analysis of thermal systems.

[0088] 3. Given the unbalanced node power, use the power system flow calculation model to solve the power flow, and then use the power system based on the flow distribution Flow indirect calculation model to solve the power system Flow distribution can realize energy quality analysis of power system.

[0089] 4. Given the non-equilibrium node gas power, the natural gas system flow calculation model is used to solve the natural gas flow rate, and then the natural gas system based on gas flow distribution is used. The indirect calculation model of the flow is used to solve the problem of natural gas system Flow distribution to achieve energy quality analysis of natural gas systems.

[0090] 5. The present invention has broad application prospects. The present invention comprehensively considers the "quantity" and "quality" of energy to establish a comprehensive energy system model. The indirect calculation method can be used to solve the comprehensive energy system under known unbalanced node power conditions in actual engineering. Flow distribution.

[0091] 6. Integrated energy system based on unbalanced node power The indirect calculation method is to obtain the unbalanced node power under known conditions. The theoretical basis of energy flow distribution provides data support for system energy quality analysis. Compared with traditional energy flow analysis, Flow distribution allows decision makers to clearly observe the effective energy distribution of the system. Compared with the traditional black box model, The acquisition of flow is conducive to analyzing the overall or local energy quality characteristics of the system, expanding the ideas of system energy quality research, and providing a theoretical basis for subsequent comprehensive energy system planning, operation optimization, control, trading and other technologies that consider energy quality, so as to achieve the rational use of high-quality energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1a and Figure 1b They are the zero potential point described in the circuit and the zero potential point described in the thermal system. Schematic diagram of potential points;

[0093] Figure 2 For simple thermal system nodes and Schematic diagram of flow composition;

[0094] Figure 3 Based on unbalanced node power Flowchart of the flow indirect calculation method;

[0095] Figure 4 is a schematic diagram of a comprehensive energy system used as an example in this embodiment;

[0096] Figure 5 The energy station structure of the comprehensive energy system used as an example in this embodiment;

[0097] Figure 6a and Figure 6b They are respectively the integrated energy system Flow Distribution and Nodes Schematic diagram of potential distribution; DETAILED DESCRIPTION

[0098] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0099] This embodiment provides a comprehensive energy system based on unbalanced node power Stream indirect calculation methods, including:

[0100] S1. Under the condition that the supply node temperature, return node temperature, outlet node temperature and water flow rate of the thermal system are known, based on the thermal system Flow mechanism model, calculate the thermal nodes Potential, construct node-branch association matrix to describe the two ends of the pipeline Potential difference, construct outflow node-branch association matrix to describe the pipeline head end Potential, and then establish a thermal system based on water flow distribution Stream indirect computation model;

[0101] S2. Under the condition of known power flow of power system, based on power system flow mechanism model, establish active power and The connection of the flow, calculate the power node trend, and then establish a power system based on power flow distribution Stream indirect computation model;

[0102] S3. Under the condition that the natural gas flow rate of the natural gas system is known, based on the natural gas system Flow mechanism model, calculate the natural gas node potential, and then establish a natural gas system based on gas flow distribution Stream indirect computation model;

[0103] S4, based on energy station Flow mechanism model, establish energy station corresponding to electricity, natural gas and heat connection nodes Flow, with nodes Loss indicates energy station Flow, and then establish an energy station based on equivalent nodes Stream indirect computation model;

[0104] S5. Combined with thermal system based on water flow distribution Flow indirect calculation model, power system based on flow distribution Flow indirect calculation model, natural gas system based on gas flow distribution Flow indirect calculation model, energy station based on equivalent nodes Flow indirect calculation model, establish a comprehensive energy system based on unbalanced node power Stream indirect computation model;

[0105] S6. Based on the unbalanced node thermal power, unbalanced node electric power, and unbalanced node gas power, a multi-energy flow calculation model is selected to solve the power flow, natural gas flow rate, water supply node temperature, return node temperature, outlet node temperature, and water flow rate of the comprehensive energy system;

[0106] Based on the supply node temperature, return node temperature and outlet node temperature of the thermal system, solve the supply node, return node and outlet node temperature Potential, combined with the water flow rate results, using a thermal system based on water flow distribution Flow indirect calculation model to solve the thermal system Flow distribution;

[0107] Based on the power flow results, a power system based on power flow distribution is adopted Flow indirect calculation model to solve the power system Flow distribution;

[0108] Based on the calculation results of natural gas flow rate and natural gas nodes The natural gas system based on gas flow distribution Flow indirect calculation model to solve the natural gas system Flow distribution;

[0109] Based on energy stations corresponding to electricity, natural gas and heat connection nodes Flow, using energy stations based on equivalent nodes Flow indirect calculation model to obtain equivalent nodes of each energy station damage;

[0110] Finally, a comprehensive energy system is formed Streams and Nodes Potential distribution.

[0111] Specific:

[0112] 1. About thermal system Flow mechanism model;

[0113] Thermal systems generally use water as a medium to supply heat energy from the source end to the load end. Thermal systems mainly include water supply networks and return water networks. Common topological forms are radial and ring. Based on the study of thermal flow in thermal systems, this example focuses on the heat flow carried by water. Don’t consider pressure etc. that are not consumed by the load

[0114] (1) Water transfers heat Calculation method

[0115] Under steady-state conditions, the heat ΔQ absorbed by a certain mass of water when its temperature changes from T2 to T1 (released when T1 changes to T2) is h (W) can be expressed as:

[0116] ΔQ h =c p m h (T1-T2) (47)

[0117] Where: c p is the specific heat capacity of water (J / (kg·K)); m h is the mass flow rate of water (kg / s).

[0118] From formula (1), we can see that the heat absorbed when the water temperature changes from T2 to T1 (released when T1 changes to T2) is Δe h (W) can be expressed as:

[0119]

[0120] Where: ∫ represents integration; T a is the ambient temperature; δQ h and δT are the differentials of heat and temperature during the water temperature change process; T is the water temperature during the change process.

[0121] First, analyze the heat transferred by water in the thermal system components The main components involved include: water supply pipes, return pipes, heat sources and loads. Consider a thermal pipe with water temperatures at both ends of the pipe being T1 and T2 respectively. The heat released by the water in the pipe to the outside world It can be expressed by formula (2). The heat absorbed and released by water at the heat source and load The same can be obtained from formula (2):

[0122]

[0123] Where: Δe h,S The amount of heat absorbed by the water in the network at the heat source Δe h,L The heat released by the water at the load to the user through the heat exchanger T s,S and T r,S are the supply and return water temperatures of the heat source (K); T s,L and T o,L are the supply and outlet temperatures of the load respectively (K); m h,S and m h,L are the water mass flow rates through the heat source and load, respectively.

[0124] (2) Thermal system The concept of potential

[0125] From equations (2) and (3), we can see that the heat transferred by the element is It is related to the ambient temperature, the temperature at both ends of the element, the water flow rate, and the specific heat capacity. Describes the heat in the thermal system This embodiment defines variables related to the component water temperature and the ambient temperature

[0126]

[0127] Where: Describes the difference between the water temperature of the component and the ambient temperature. In electrical theory, the electric field potential difference is the work done by a unit positive charge moving from one point to another. By analogy with formula (2), we can know that the water temperature at both ends of the component corresponds to and The difference can be expressed as the heat transferred by unit mass water from temperature T1 to T2

[0128]

[0129] Analogous to the concept of potential difference, the above formula corresponds to different water temperatures. difference Defined as Potential difference.

[0130] Furthermore, considering that the definition of potential in circuit theory is closely related to potential difference, such as Figure 1a As shown, the node potential is the potential difference (voltage) between the point and the reference point. The reference point can be any point in the circuit, and the earth is generally selected as the zero potential point. In thermal science, the environmental state is often regarded as The baseline state, such as Figure 1b As shown, based on Flow theory, analogous to the zero potential point in the circuit, select the corresponding ambient temperature As the reference point, define the zero point of the thermal system The temperature of a node in a thermal system corresponds to the ambient temperature. The potential difference is defined as the Potential T (J / kg), as shown in the following formula:

[0131]

[0132] Where: The ambient temperature corresponds to T = T a Substituting into formula (6), we can get the corresponding ambient temperature Potential Ta is zero, that is, the reference point of the thermal system The potential is zero.

[0133] (3) Thermal system Definition of Stream

[0134] According to the second law of thermodynamics, the energy of the environment is Therefore, water carries about 1% of the heat flow at ambient temperature. is zero. Define the heat flow at a certain location in a thermal system. =The heat absorbed by water when it is heated from ambient temperature to the current temperature T This section As water flows in the network, this invention refers to it as the flow.

[0135] The power flow of the power system is often described by the power at the beginning and end of the line. Flow theory, this embodiment uses the first end of the element Stream Description Element Stream, based on the headend Flow and heat transferred by the element Available end Flow. Figure 2 As shown, the head and the end of the elements in the thermal system are connected through various nodes, which mainly include: heat source water supply node, heat source return water node, load water supply node, load outlet node, load return water node, connection node of water supply network and return water network, etc.

[0136] element Flow and connected nodes Potential related, near the node Flow is the surrounding directly connected elements From formula (2), we can see that the water near the node is controlled by the ambient temperature T a When heated to temperature T, the amount of heat absorbed Δe h,Ta It can be expressed as:

[0137] Δe h,Ta =(TT a lnT-T a +T a oeLh a )c p m h (53)

[0138] based on Flow theory, near nodes of thermal systems The flow can be calculated by formula (7), combined with formula (6) The potential definition is: when the node water temperature is T, the node near Flows can be represented as thermal nodes The product of potential and water mass flow rate:

[0139] e h =Δe h,Ta =p T m h (54)

[0140] From equations (2), (5) and (6), we can see that the heat transferred by the element is It can be expressed as the water temperature at both ends of the element The product of the potential difference and the mass flow rate of water flowing through the element is:

[0141]

[0142] Where: p T1 and p T2 The nodes corresponding to temperatures T1 and T2 are Momentum.

[0143] According to Ohm's law, the power consumed by the resistor in the circuit is equal to the product of the potential difference and the current. From formula (9), we can see that: The potential is similar to the electric potential in the circuit. The heat transferred by the components in the thermal system equal The product of potential difference and water mass flow rate. Analogous to the physical meaning of electric potential, Potential is the heat transferred by unit mass water from ambient temperature to actual temperature The potential determines the amount of water of the same mass carried at different locations in the system. The value size can be regarded as A measure of flow. The potential difference means the amount of heat transferred by a unit mass of water during temperature change. size.

[0144] Figure 2 It is a typical double-layer topological thermal system with a symmetrical water supply and return network. The load and heat source can be regarded as the elements between the water supply and return network. Flow distribution consists of three parts:

[0145] (1) Damage, including supply and return pipes Loss and Load damage;

[0146] (2) Heat source and load

[0147] (3) Components Flow, including supply and return pipes Flow, flow into heat source Flow, inflow load Inflow and outflow loads Based on the above The flow distribution can obtain the flow of the effective energy of the entire thermal system. The following is a detailed analysis:

[0148] 1) Water supply and return pipes damage

[0149] There is heat loss in the water supply and return pipes, accompanied by loss, it can be seen from formula (9) that the pipeline The loss can be expressed as the two end nodes Potential difference and pipe water flow rate m h The product of:

[0150]

[0151] Where: Δe h,sl and Δe h,rl Water supply and return pipes Loss; p s1 and p s2 They are the nodes at both ends of the water supply pipeline. potential; p r1 and p r2 They are the nodes at both ends of the return pipe. Momentum.

[0152] 2) Heat source and load

[0153] The amount of heat absorbed by water at the heat source (Heat Source ) and the heat released at the load (load ) and pipeline The heat loss is similar to that of the heat source. Δe h,S Can be represented as a water supply node Potential s and return water node Potential r The product of the difference and the heat source water flow rate, load Δe h,L Can be represented as a water supply node Potential and exit nodes Potential o The product of the difference and the load water flow rate:

[0154]

[0155] Heat Source ,load With pipeline There are differences in the loss of pipelines. The heat source is not used. To provide heat to the system load Heat consumed by the load All are considered available Rather than damage.

[0156] 3) Load damage

[0157] like Figure 2 As shown in the figure, when the return water node is a mixed node, the water flowing out of the load mixes with the water in the return water network, and the water temperature changes. There are differences in potential, which leads to Changes in this section is not used by the load, so the present invention regards it as a kind of Loss, from formula (9), we can know that this part Loss Δe h,Ll It can be expressed as:

[0158] Δe h,Ll =(p o -p r )m h,L (58)

[0159] 4) Components flow

[0160] like Figure 2 As shown, it is assumed that the supply and return water networks are completely symmetrical, and the water loss in the pipes is ignored. To ensure the continuity of the water flow, the water flow rates in the corresponding supply and return water pipes are the same but in opposite directions. The flow is in the same direction as the water flow, corresponding to the The flow direction is opposite. From formula (8), we can see that the supply and return pipes A flow can be represented as a head node The product of potential and water flow rate:

[0161]

[0162] Where: e h,s and e h,r Water supply and return pipes Flow, p s and p r The first end nodes of the water supply pipeline Potential and return pipe head end node Momentum.

[0163] Similarly, if Figure 2 As shown, the inflow load Stream h,sL Can be regarded as load Flow, which can be represented as a load water supply node The product of the potential and the load water flow rate; the flow into the heat source Stream h,rS Can be considered as heat source Flow, which can be represented as a heat source return node The product of potential and heat source water flow rate will not be repeated.

[0164] If the load The loss is regarded as the heat released by the components between the outlet node and the return node. Outflow load Stream h,oL This component can be considered Flow, flowing out from the load outlet node, can be represented as the load outlet node The product of the potential and the load water flow rate. h,oL Part of the load Loss Δe h,Ll , and the other part is connected to the return water network Streams meet.

[0165] From the above analysis, it can be seen that the thermal system Flow distribution and thermal nodes Potential, water flow rate, thermal nodes The potential can be obtained from the temperature calculation. Therefore, the water flow rate and temperature are obtained based on the measurement or multi-energy flow calculation, and then the thermal system is calculated by equations (10)-(13). Flow distribution.

[0166] 2. Power system Flow Mechanism Model

[0167] In energy quality analysis, electrical energy can be completely converted into work or other forms of energy, which is high-quality energy and can be regarded as Therefore, the active power flow of the power system is The active power loss is Three-phase symmetrical AC power system (hereinafter referred to as power system) flow and harmony The loss can be expressed as:

[0168] e e =P e (60)

[0169] Δe e =ΔP e (61)

[0170] Where: e e and P e The power lines flowing through Current and active power (kW); Δe e and ΔP eFor lines loss and active power loss.

[0171] Based on measurement or power flow calculation, the active power flow distribution and active power loss of the power system can be obtained, and then calculated by equations (14) and (15): Flow distribution.

[0172] The present invention regards the current as the medium flow rate of the power system. flow and harmony The loss can be expressed as:

[0173]

[0174] Where: It means the real part of a complex number; is the line voltage phasor at the head end of the power line (kV∠rad); is the conjugate of the line current phasor flowing through the line (A∠rad); and are the line voltage phasors at both ends of the line respectively.

[0175] From equations (16) and (17), we can see that the line The flow can be represented by the line voltage and line current, The loss can be represented by the line voltage difference and the line current. Potential, reflecting the unit current carried flow. The potential difference reflects the unit current generated on the line damage.

[0176] 3. Natural gas system Flow Mechanism Model

[0177] The natural gas system supplies gas to users through the pipeline network. The current natural gas energy measurement standards "Technical Requirements for Natural Gas Metering System: GB / T18603-2014" and "Determination of Natural Gas Energy: GB / T 22723-2008" propose that the energy of a certain amount of natural gas can be expressed as the product of the amount of gas and the calorific value, and the calorific value is the calorific value. This energy measurement formula is widely used in engineering practice. In the IES multi-energy flow research, natural gas is regarded as a medium for transmitting energy. The above energy measurement formula is used to measure the energy of natural gas, and the conversion between the gas power and the airflow rate included in the load and multi-energy coupling links is realized. Therefore, thermal power is used to measure the natural gas energy in steady state, that is, gas power, and pressure energy and other energies that are not consumed by the multi-energy coupling links and loads are not taken into account. Gas power can be calculated from the airflow rate and the total calorific value:

[0178]

[0179] Where: φ g and m g are the natural gas power (kW) and flow rate (m 3 / h; G is the total calorific value of natural gas (MJ / m 3 ).

[0180] The energy of natural gas is measured in terms of thermal power, the fuel consumed by gas loads It is equivalent to the heat generated by heating the ambient temperature to the theoretical combustion temperature during the combustion of natural gas. Natural gas Stream g (kW) can be expressed as the energy quality coefficient λ of natural gas g The product of gas power:

[0181]

[0182] Where: T b is the theoretical combustion temperature of natural gas (K).

[0183] based on Flow theory, when the ambient temperature, natural gas theoretical combustion temperature and total calorific value are constant, natural gas The gas flow is determined by the gas flow rate. If the loss of pipeline natural gas and the change of gas quality are ignored, the natural gas system can be regarded as non- Lossless network, no Loss refers to the heat consumed by load and multi-energy coupling links. There is no loss in the transmission process. The pipeline pressure drop under steady-state conditions determines the distribution of airflow in the system, which in turn determines The distribution of gas flow Although the pressure effect is not considered in the flow analysis, However, it is necessary to consider its impact on The influence of flow distribution. From formula (19), we can know that The flow can be regarded as the natural gas flow rate m g With constant p g The product of:

[0184]

[0185] From equations (19) and (20), we can see that the constant p g Can be regarded as a natural gas system potential, which means the unit airflow rate The unit is kWh / m 3 . Gas pipeline The flow can be expressed as the natural gas flow rate and The product of potential, both ends of the gas pipeline The potential difference is zero, The loss can be considered as the two ends The product of the potential difference and the gas flow rate, therefore, ignoring the loss of pipeline natural gas and the change in gas quality, the natural gas system meets the requirement of no The gas flow rate is obtained based on measurement or multi-energy flow calculation, and then the gas flow rate of the natural gas system is calculated by formula (19). Flow distribution.

[0186] 4. Energy Station Flow Mechanism Model

[0187] Energy stations are the key multi-energy coupling link of IES, involving the conversion of various energy forms of different qualities, and are the focus of IES energy quality research. Traditional multi-energy flow research usually uses the energy hub model to describe energy stations, and determines the coupling relationship between energy networks through the balance relationship between the input and output port electrical power, gas power, and thermal power. Therefore, the energy station The analysis also considers electrical energy Natural gas fuel Heat transferred to water Analogous to the modeling ideas of PQ and PV nodes in power system flow calculation, this invention does not focus on the specific energy conversion links within the energy station. change process, but pay attention to the energy conversion process Loss, using Loss represents the energy station equivalent node Flow, this part Loss EH,l It can be solved by the following formula:

[0188] e EH,l =e EH,e +e EH,g +e EH,h (67)

[0189] Where: e EH,e 、e EH,g 、e EH,h The electrical energy consumed or supplied by the energy station in the power system Fuel consumed or supplied in a natural gas system The amount of heat consumed or supplied in a thermal system e EH,e 、e EH,g 、e EH,h For consumption When , the corresponding element takes a positive value; for supply , the corresponding element takes a negative value; otherwise, it takes zero.

[0190] 5. Thermal system based on water flow distribution Stream indirect computing model

[0191] From formula (11), we can get that for a large-scale thermal system, the heat source transfers heat For water supply and return nodes The product of the potential difference and the water flow rate can be expressed in matrix form as:

[0192] Δe h,S =diag(p s -p r )m h,S (68)

[0193] Where: Δe h,S n h,n Heat source Column vector, n h,n is the number of water supply nodes; diag(·) represents the diagonal matrix composed of the elements in the vector; p s and p r n h,n Maintain water supply and return nodes Potential column vector; m h,S n h,n dimensional heat source water flow rate column vector, when the i-th node is a heat source water supply node, m h,S The i-th element of is the water flow rate of this node, and the other elements are 0. The present invention selects the water flow direction from the supply water to the return water node as positive, m h,S and Δe h,S The non-zero elements of are negative.

[0194] Similarly, the load transfers heat Can be represented as supply and return nodes The product of the potential difference and the water flow rate can be expressed in matrix form as:

[0195] Δe h,L =diag(p s -p o )m h,L (69)

[0196] Where: Δe h,L n h,n Heat load Column vector; p o n h,n Dimension Exit Node Potential column vector; m h,L n h,n dimensional heat load water flow rate column vector, when the i-th node is a heat load water supply node, m h,L The i-th element of is the water flow rate of this node, and the other elements are 0. h,L and Δe h,L Non-zero elements are positive values.

[0197] From formula (12), we can see that in the thermal system, some heat load outlet nodes Potential and Return Nodes There is a difference in potential, so load Loss, this part The loss can be represented as the outlet and return nodes. The product of the potential difference and the water flow rate is expressed in matrix form as:

[0198] Δe h,Ll =diag(p o -p r )m h,L (70)

[0199] Where: Δe h,Ll n h,n Dimensional load Loss column vector.

[0200] The system topology can be described by the node-branch association matrix. Based on formula (10), for a large-scale thermal system, the two ends of the water supply pipe are The potential difference can be obtained by combining the node-branch association matrix and the node The potential vector represents the water supply pipeline The loss can be expressed as:

[0201]

[0202] Where: Δe h,s n h,p Maintain water supply pipelines Loss vector, n h,p is the number of water supply pipes; m h is the water flow rate column vector of the water supply pipe, with dimension n h,p ; T Represents the transpose of the matrix; A h is the node-branch association matrix of the water supply network, with dimension n h,n ×n h,p .

[0203] Assuming that the water supply network and the return network are completely symmetrical and the water flow loss is ignored, the node-branch association matrix of the return network can be regarded as -A h Similarly, the return pipe Loss vector Δe h,r It can be expressed as:

[0204]

[0205] From formula (13), we can see that the pipeline The flow is mainly composed of water flowing out of the node in the pipe. Based on the potential, the outflow node-branch association matrix and the inflow node-branch association matrix of the water supply network can be defined to characterize the topological relationship between branches and outflow and inflow nodes.

[0206] Among them, the outflow node-branch association matrix A h,- The elements in can be represented as:

[0207]

[0208] Where (i, j) represents the element in the i-th row and j-th column of the matrix.

[0209] Affected by the symmetry of the water supply and return network, the inflow node-branch association matrix A of the water supply network is h,+ That is, the outflow node-branch association matrix of the backwater network, whose elements are:

[0210]

[0211] A h,- For-A h The matrix A is composed of 1 h,+ A h The matrix composed of 1 has a dimension of n h,n ×n h,p , and satisfy:

[0212] A h =-A h,- +A h,+ (75)

[0213] Based on the above four types of association matrices, nodes The potential column vector and the water flow rate column vector of the water supply pipe can be expressed in the form of matrices to represent the water supply and return pipes respectively. flow:

[0214]

[0215] Where: e h,s and e h,r Water supply and return pipes Flow column vector, dimension is n h,p .

[0216] In summary, the water flow rate and water temperature of each node are solved based on the thermal flow, and the supply, return and outlet nodes are constructed. Potential vector, using equations (22)-(31) to solve the large-scale thermal system Flow distribution.

[0217] 6. Power system based on power flow distribution Stream indirect computing model

[0218] From equations (14) and (15), we can see that the power line flow, Loss and source load It can be expressed as a vector:

[0219]

[0220] Where: e e , Δe e , P e and ΔP e n e,l Maintaining power lines flow, loss, transmission active power and active power loss column vector, n e,l is the number of power lines; e e,N and P e,N n e,n Weiyuanhe and source-load power column vector, the corresponding elements of load are positive, the corresponding elements of power supply are negative, and the corresponding elements of connection nodes are 0, n e,n is the number of power nodes.

[0221] Under the condition of known unbalanced node power, the active power flow distribution can be solved by using algorithms such as the Newton method, PQ decomposition method and forward-backward substitution method to obtain the power system The current distribution and active power loss are The voltage is the power system Momentum.

[0222] 7. Natural gas system based on air flow distribution Stream indirect computing model

[0223] The steady-state analysis of natural gas networks often uses the non-equilibrium node airflow rate as a known quantity to represent the power provided by the gas source or consumed by the load. Based on the energy flow of the natural gas system, the pipeline airflow rate distribution is solved and the energy consumption of each node is obtained. potential, and thus obtain the natural gas system Considering a large-scale natural gas system, equations (19) and (20) are expressed in matrix form. The stream computing model can be expressed as:

[0224]

[0225] Where: e g and m g n g,p Natural gas pipeline Column vector of flow and airflow rate, n g,p is the number of natural gas pipelines; e g,N and m g,Nn g,n Natural gas source load and the airflow rate vector, n g,n is the number of gas nodes.

[0226] 8. Energy station based on equivalent nodes Stream indirect computing model

[0227] Based on formula (21), the energy station is expressed in vector form The losses are as follows:

[0228] e EH,l =e EH,e +e EH,g +e EH,h (80)

[0229] Where: e EH,l Energy station node Loss column vector; e EH,e 、e EH,g and e EH,h The energy stations correspond to electricity, natural gas and heat (heat source) or load )Connected Node The flow column vector has the dimension of the number of energy stations in the system. If the i-th energy station has no connected node of the k-th energy form, then e EH,k The i-th element is 0, as shown below:

[0230] e EH,k (i,1)=0, k∈[e,g,h] (81)

[0231] 9. Based on unbalanced node power Stream Indirect Computation Method

[0232] When the unbalanced node power is known, the integrated energy system The flow solution can be based on the multi-energy flow calculation results, and based on the multi-energy flow parameters such as power flow, natural gas flow rate, node temperature, water flow rate, etc., the integrated energy system (IES) can be obtained. Flow distribution, the specific calculation process is as follows Figure 3 As shown:

[0233] 1) Based on the unbalanced node power, network topology, pipeline parameters, energy station equipment model and operation mode data, a multi-energy flow calculation model is selected to solve the power flow, natural gas flow rate, water supply node temperature, return water node temperature, outlet node temperature and water flow rate of the comprehensive energy system;

[0234] 2) Obtain the power system nodes through the voltage in the power system The power system is obtained by the power flow distribution and power source and load power in the power system. Flow distribution, power systems Flow distribution includes flow and harmony Loss and source load

[0235] 3) By gas node The potential and natural gas flow rate are used to obtain the natural gas system Flow distribution, natural gas systems Flow distribution including natural gas pipelines Flow and natural gas source load

[0236] 4) Obtain the temperature of the water supply node, return water node and outlet node according to the temperature of each node in the thermal system potential, through each node Potential and water flow rate to solve the thermal system Flow distribution, thermal system Flow distribution includes various elements flow, Loss, load and heat source

[0237] 5) Based on the energy station corresponding to the electricity, natural gas and heat connection nodes Flow, obtain the equivalent nodes of each energy station damage;

[0238] 6) Forming an integrated energy system Streams and Nodes Potential distribution.

[0239] The following example implements the above-mentioned integrated energy system based on unbalanced node power. The specific application of the flow indirect calculation method is described below:

[0240] analyze Figure 4 The small-scale IES shown in the figure, G1-G5 are natural gas nodes, forming a 5-node low-pressure gas distribution system, the gas source pressure is 30mbar, and the calorific value of natural gas is 45.574MJ / m 3 , the theoretical combustion temperature is 1973℃. H1-H3 are thermal nodes, the water supply temperature of the heat source is 100℃, the outlet temperature of the load is 50℃; the ambient temperature is 10℃. E1-E6 are power nodes, forming a 6-node power system, and the source terminal voltage is 12.66kV. The energy station structure and external node connection relationship are as follows Figure 5As shown in the figure, the energy conversion equipment used is a gas boiler (GB) and a combined heat and power (CHP) unit, of which the gas-to-heat conversion efficiency of GB is 0.9, and the gas-to-electricity and gas-to-heat conversion efficiencies of CHP are 0.3 and 0.4 respectively. The energy station adopts the operation mode of determining electricity by heat, and the natural gas allocation coefficient of CHP is 0.5. The energy station is a load node G5 in the natural gas system, the only heat source H1 in the thermal system, and the power node E6 in the power system.

[0241] Table 1 Unbalanced node power parameters for the example

[0242]

[0243] According to the unbalanced node power parameters shown in Table 1, the unbalanced node power IES calculation by flow indirect calculation method Flow distribution, first solve the multi-energy flow results of IES.

[0244] According to the node potential and power flow results, nodes of the power system The trend is shown in Table 2. flow and harmony The energy loss is shown in Table 3. The energy quality coefficient of natural gas is calculated to be 0.70 based on the ambient temperature and the theoretical combustion temperature of natural gas. The potential results are shown in Table 4, all of which are 8.88 kWh / m 3 . According to the node potential and gas flow results, calculate the gas system The flow distribution is shown in Table 5.

[0245] Table 2 Power system nodes Potential (kV∠rad)

[0246]

[0247] Table 3 Power system Flow distribution (kW)

[0248]

[0249] Table 4 Natural gas system nodes Potential (kWh / m 3 )

[0250]

[0251] Table 5 Natural gas system Flow distribution (kW)

[0252]

[0253] Based on the multi-energy flow results of the thermal system such as the water supply, outlet, and return water temperatures of the thermal system, the corresponding ambient temperature of 10°C is selected. Zero potential Potential points, calculate the supply, outlet and return nodes The trend is shown in Table 6.

[0254] Table 6 Thermal system nodes Potential (kJ / kg)

[0255]

[0256]

[0257] According to the thermal system node potential, and water mass flow rate, to calculate the entire thermal system Flow distribution, components Stream, Pipe The loss calculation results are shown in Table 7. load load The loss calculation results are shown in Table 8.

[0258] Table 7 Thermal system Streams and Pipes Loss distribution (kW)

[0259]

[0260] Table 8 Heat Source load and load Loss(kW)

[0261]

[0262] According to the nodes of E6, G5 and H1 of the electricity, natural gas and heat systems Flow results, calculate energy stations The loss is 597.83kW. The flow calculation results show the Flow distribution Figure 6a As shown in Table 3 and Figure 6a It can be seen that there are lines in the power system Loss, no load damage. Figure 6a The data shows that for the power system, the lines flowing into the node Flow and node power supply The sum is equal to the route out of the node Flow and node load consumption line The sum of the losses satisfies the local At the same time, the power supply from the source of the power system is 1516.22kW, and the load consumption is is 1512.33kW, The loss is 3.89kW, and the source end supplies Equal to the load consumption and The sum of losses satisfies the whole Balanced relationship.

[0263] From Table 5 and Figure 6a It can be seen that the natural gas system does not exist damage, The flow is numerically 8.88 times the airflow rate. Figure 6a The data show that for each node in the natural gas system, the pipelines flowing into the node Flow and node gas supply The sum is equal to the pipe out of the node Flow and node load consumption The sum satisfies the local Balance relationship. At the same time, the system gas source is 3912.52kW, load It is 3912.52kW, which meets the overall Balanced relationship.

[0264] From Table 6 and Figure 6a It can be seen that the return node of H2 is a mixing node, and the outlet node of H2 Potential and Return Nodes The potential is not equal, so the thermal system has a return node at H2 damage. Figure 6a The data show that for each node of the thermal system, the first end of the element flowing into the node Flow and heat source connected to the node The sum is equal to the end of the element flowing out of the node The load consumed by the flow and node element The sum of the losses satisfies the local Balance relationship. At the same time, the heat source of the system is 166.25kW, load 158.95kW, water supply and return network The losses are 5.94kW and 1.03kW respectively, and the load The loss is 0.33kW, the heat source Equal to load and system The sum of losses satisfies the whole Balanced relationship.

[0265] Analogous to the voltage distribution of the power system, Figure 6b Shows the system nodes The distribution of potential. Nodes of the power system Potential is expressed in terms of magnitude (kV) and phase angle (rad); nodes in natural gas systems The potential is 8.88kWh / m3.

[0266] For the thermal system, the water supply nodes of the heat source H1 and the load H3 The potentials are 49.55 kJ / kg and 47.58 kJ / kg respectively, that is, the water per unit mass near the node carries The values ​​are 49.55kW and 47.58kW respectively, indicating that the water near H1 has a higher capacity to carry high-quality energy than H3. The higher the potential, the higher the energy quality of the location.

[0267] Load H2 and H3 water supply and export nodes The potential differences are 38.01 kJ / kg and 36.77 kJ / kg respectively, that is, the unit mass of water in H2 and H3 supplies the load. They are 38.01kW and 36.77kW respectively. Same supply potential Load, H3 requires a larger water flow rate. Example data shows the supply and return nodes The higher the potential difference, the higher the ability to supply high-quality energy to the load. The potential is equal, the supply and return nodes The potential difference is determined by the water supply node The water supply node is determined by the situation The higher the potential, the higher the ability to supply high-quality energy to the load. In addition, analyze the outlet and return nodes of H2 and H3. The potential difference shows that the return water node The potential also reflects the load The extent of damage.

[0268] From the above, it can be seen that the system Potential can be used as an important parameter to reflect the local energy quality of the thermal system.

[0269] Input of the entire IES The output is 5220.84kW. is 4611.81kW, network Loss, load Loss, Energy Station The total loss is 609.03kW. The efficiency is 88.33%, and the whole system meets Therefore, each energy system and the entire IES meet the local and overall Balanced relationship, compared with the traditional black box model, based on The flow mechanism model can quantitatively analyze the distribution of effective energy within the energy network and realize the quantitative and qualitative coordinated research of the system. The loss ratio is 98.16%, which is the total loss ratio of the system. GB and CHP convert a large amount of medium-quality natural gas into low-quality thermal energy to meet heating needs. Although some high-quality electricity is also generated, the above energy conversion mode makes the total The loss shows an increasing trend.

[0270] IES based on traditional black box model Analysis is usually based on the energy quality coefficient The calculation method obtains the input and output electrical energy of the system fuel Heat Furthermore Efficiency is used as the optimization target for other calculations, and less attention is paid to the IES network. The example uses a black box model based on Analytical method, the energy quality coefficient and The values ​​are shown in Table 9. It can be seen that the source and load With this article The calculation results of the flow mechanism model are the same, the system The efficiency solution is the same. The flow mechanism model can also obtain the energy quality coefficient results shown in Table 9.

[0271] Depend on Figure 6a and Figure 6b It can be seen that compared with the traditional black box model Analytical methods, The flow mechanism model can not only solve the source and load ,system efficiency, and can also clearly present the status of each link and pipeline in the IES network. Flow distribution and Damage situation, As a measure of energy quality, it reflects the overall and local energy quality characteristics of the system under the current operating state. The establishment of potential provides ideas for local energy quality analysis. Flow distribution establishes source, network, and load Contact for the future It provides a theoretical basis for measurement, pricing, and trading, while the black box model The above applications are difficult to achieve with analytical methods. The flow mechanism model can also be combined with Concepts such as efficiency can be used to achieve energy quality analysis of the entire energy system or a certain type of energy system, energy station, a certain area within the system, node, or pipeline, providing ideas for building a high-quality energy system.

[0272] Table 9 Sources and loads based on energy quality coefficient Calculation results

[0273] #imgpt676#

[0274] Unless otherwise specified, the models of the components in the embodiments of the present invention are not limited, and any device that can perform the above functions may be used.

[0275] Those skilled in the art will appreciate that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0276] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0277] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. An integrated energy system based on unbalanced node power The flow indirect calculation method is characterized by: include: S1. Based on the thermal system, the water supply node temperature, return node temperature, outlet node temperature and water flow rate of the thermal system are known. Flow mechanism model, calculate the thermal nodes Potential, construct node-branch association matrix to describe the two ends of the pipeline Potential difference, construct outflow node-branch association matrix to describe the pipeline head end Potential, and then establish a thermal system based on water flow distribution Stream indirect computation model; When the heat load is known, the pipeline water flow rate and the water temperature of the supply, return and outlet nodes are calculated based on the thermal flow calculation to obtain the temperature of each node. potential, based on Potential and flow rate solution Flow Loss distribution; according to the water temperature T at the node, the ambient temperature T a , defining the nodes of the thermal system Potential T for: p T =(T-T a lnT-T a +T a lnT a )c p (1) Where: c p is the specific heat capacity of water; node Potential T Reflects the unit water flow rate ,node Potential difference Δp T Reflects the heat transferred per unit water flow rate ; According to the node Potential and water flow rate, calculation elements Flow and components transfer heat ; Among them, the components Flow The product of potential and water flow rate, the heat transferred by the element for The product of potential difference and water flow rate: Where: e h For components flow;m h is the water flow rate; p T Nodes connected to the component Potential; Δe h Transfer heat to components ,include Loss and heat source load ;Δp T The nodes at both ends of the component potential difference; For large-scale thermal systems, the heat source transfers heat For water supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,S sdiag(p s -p r )m h,S (3) Where: Δe h,S For heat source Column vector; diag(·) represents a diagonal matrix consisting of the elements in the vector; p s and p r They are respectively the supply and return nodes Potential column vector; m h,S is the heat source water flow rate column vector. When the i-th node is the heat source water supply node, m h,S The i-th element of is the water flow rate of this node, and the other elements are 0; the water flow direction from the supply water to the return water node is selected as positive, m h,S and Δe h,S The non-zero elements of are negative; Similarly, the load transfers heat Represented as supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,L sdiag(p s -p o )m h,L (4) Where: Δe h,L For load Column vector; p o For the exit node Potential column vector; m h,L is the load water flow rate column vector. When the i-th node is a load water supply node, m h,L The i-th element of is the water flow rate of this node, and the other elements are 0; m h,L and Δe h,L Non-zero elements are positive values; In thermal systems, some load outlet nodes Potential and Return Nodes There is a difference in potential, which generates load Loss, this part Loss is represented by outlet and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,Ll sdiag(p o -p r )m h,L (5) Where: Δe h,Ll For load Loss column vector; The node-branch association matrix is ​​used to describe the thermal system topology. For a large-scale thermal system, the nodes at both ends of the water supply pipe are The potential difference is determined by the node-branch association matrix and the node The potential vector represents the water supply pipeline The loss is expressed as: Where: Δe h,s For water supply pipes Loss vector, n h,p is the number of water supply pipes; m h is the column vector of water flow rate in the water supply pipe; T Represents the transpose of the matrix; A h is the node-branch association matrix of the water supply network; Assuming that the supply network and the return network are completely symmetrical and that water flow losses are ignored, the node-branch association matrix of the return network is considered to be -A h ; Similarly, the return pipe Loss vector Δe h,r It is expressed as: Based on thermal system Flow Mechanism Model, Pipeline The flow is mainly composed of water flowing out of the node in the pipe. The outflow node-branch association matrix and the inflow node-branch association matrix of the water supply network are defined to characterize the topological relationship between the branches and the outflow and inflow nodes; Among them, the water supply network outflow node-branch association matrix A h,- The elements in are represented as: Where: (i, j) represents the element in the i-th row and j-th column of the matrix; Affected by the symmetry of the water supply and return network, the water supply network inflow node-branch association matrix A h,+ That is, the outflow node-branch association matrix of the backwater network, whose elements are: A h,- A h The matrix A is composed of 1 h,+ A h The matrix composed of 1 in , and satisfies: A h =-A h,- +A h,+ (10) Based on the above association matrix, node Potential column vector, water flow rate column vector of water supply pipe, and matrix form to represent water supply and return pipes respectively flow: Where: e h,s and e h,r Water supply and return pipes Flow column vector; Based on the thermal flow, the water flow rate of the water supply network and the water temperature of each node are solved to build the water supply, return water and outlet nodes Potential vector, using equations (3)-(12) to solve the large-scale thermal system Flow distribution; S2. Under the condition of known power flow of power system, based on power system flow mechanism model, establish active power and The connection of the flow, calculate the power node trend, and then establish a power system based on power flow distribution Stream indirect computation model; S3. Under the condition that the natural gas flow rate of the natural gas system is known, based on the natural gas system Flow mechanism model, calculate the natural gas node potential, and then establish a natural gas system based on gas flow distribution Stream indirect computation model; S4, based on energy station Flow mechanism model, establish energy station corresponding to electricity, natural gas and heat connection nodes Flow, with nodes Loss indicates energy station Flow, and then establish an energy station based on equivalent nodes Stream indirect computation model; S5. Combined with thermal system based on water flow distribution Flow indirect calculation model, power system based on flow distribution Flow indirect calculation model, natural gas system based on gas flow distribution Flow indirect calculation model, energy station based on equivalent nodes Flow indirect calculation model, establish a comprehensive energy system based on unbalanced node power Stream indirect computation model; S6. Based on the unbalanced node power, select the multi-energy flow calculation model to solve the power flow, natural gas flow rate, water supply node temperature, return node temperature, outlet node temperature and water flow rate of the comprehensive energy system; Based on the supply node temperature, return node temperature and outlet node temperature of the thermal system, solve the supply node, return node and outlet node temperature Potential, combined with the water flow rate results, using a thermal system based on water flow distribution Flow indirect calculation model to solve the thermal system Flow distribution; Based on the power flow results, a power system based on power flow distribution is adopted Flow indirect calculation model to solve the power system Flow distribution; Based on the calculation results of natural gas flow rate and natural gas nodes The natural gas system based on gas flow distribution Flow indirect calculation model to solve the natural gas system Flow distribution; Based on energy stations corresponding to electricity, natural gas and heat connection nodes Flow, using energy stations based on equivalent nodes Flow indirect calculation model to obtain equivalent nodes of each energy station damage; Finally, a comprehensive energy system is formed Streams and Nodes Potential distribution.

2. The integrated energy system based on unbalanced node power according to claim 1 The flow indirect calculation method is characterized by: In step S2: line flow, Loss and source load Expressed as a vector: Where: e e , Δe e , P e and ΔP e Power system flow, loss, transmission active power and active power loss column vector; e e,N and P e,N Power source and load The power column vector of the power source and load, the corresponding elements of the load are positive, the corresponding elements of the power source are negative, and the corresponding elements of the connection node are 0; Under the condition of known unbalanced node power, the active power flow distribution can be solved by using algorithms such as the Newton method, PQ decomposition method or forward-backward substitution method to obtain the power system The current distribution and active power loss are The voltage is the power system Momentum.

3. The integrated energy system based on unbalanced node power according to claim 1 The flow indirect calculation method is characterized by: In step S3: The steady-state analysis of natural gas network takes the non-equilibrium node gas flow rate as a known quantity to represent the power provided by the gas source or consumed by the load; the pipeline gas flow rate distribution is solved based on the energy flow of the natural gas system, and the gas flow rate of each natural gas node is obtained. potential, and thus obtain the natural gas system Flow distribution, gas nodes Potential g It is expressed as: Where: T b is the theoretical combustion temperature of natural gas; G is the calorific value of natural gas; ambient temperature T a ; Considering the large-scale natural gas system, the natural gas system The stream indirect computation model is expressed as: Where: e g and m g Natural gas pipeline Flow and airflow rate column vector; e g,N and m g,N Natural gas source load and the airflow rate vector.

4. The integrated energy system based on unbalanced node power according to claim 1 The flow indirect calculation method is characterized by: In step S4: The energy station is equivalent to the integrated form of electricity, natural gas and heat nodes. Based on the multi-energy flow results, the energy system The flow indirect calculation model obtains the equivalent nodes of the energy station flow, the energy station is equivalent to Damaged nodes are represented by vectors. damage: And EH,l =and EH,e +e EH,g +e EH,h (16) Where: e EH,l Energy station node Loss column vector; e EH,e 、e EH,g and e EH,h They are the nodes corresponding to electricity, natural gas and heat in the energy station. Flow column vector, if the i-th energy station has no connected node of the k-th energy form, then e EH,k The i-th element is 0, as shown below: e EH,k (i,1)=0,k∈[e,g,h] (17)。 5. The integrated energy system based on unbalanced node power according to claim 1 The flow indirect calculation method is characterized by: In step S5, 1) Based on the unbalanced node power, network topology, pipeline parameters, energy station equipment model and operation mode data, a multi-energy flow calculation model is selected to solve the power flow, natural gas flow rate, water supply node temperature, return water node temperature, outlet node temperature and water flow rate of the comprehensive energy system; 2) Obtain the power system nodes through the voltage in the power system The power system is obtained by the power flow distribution and power source and load power in the power system. Flow distribution, power systems Flow distribution includes flow and harmony Loss and source load ; 3) By gas node The potential and natural gas flow rate are used to obtain the natural gas system Flow distribution, natural gas systems Flow distribution including natural gas pipelines Flow and natural gas source load ; 4) Obtain the temperature of the water supply node, return water node and outlet node according to the temperature of each node in the thermal system potential, through each node Potential and water flow rate to solve the thermal system Flow distribution, thermal system Flow distribution includes various elements flow, Loss, load and heat source ; 5) Based on the energy station corresponding to the electricity, natural gas and heat connection nodes Flow, obtain the equivalent nodes of each energy station damage; 6) Forming an integrated energy system Streams and Nodes Potential distribution.

6. An integrated energy system based on unbalanced node power A stream indirect computing device, characterized in that include: Thermal system Flow indirect calculation unit, used to calculate the thermal system Flow mechanism model establishment based on water flow distribution thermal system Stream indirect computation model; When the heat load is known, the pipeline water flow rate and the water temperature of the supply, return and outlet nodes are calculated based on the thermal flow calculation to obtain the temperature of each node. potential, based on Potential and flow rate solution Flow Loss distribution; according to the water temperature T at the node, the ambient temperature T a , defining the nodes of the thermal system Potential T for: p T =(T-T a lnT-T a +T a lnT a )c p (18) Where: c p is the specific heat capacity of water; node Potential T Reflects the unit water flow rate ,node Potential difference Δp T Reflects the heat transferred per unit water flow rate ; According to the node Potential and water flow rate, calculation elements Flow and components transfer heat ; Among them, the components Flow The product of potential and water flow rate, the heat transferred by the element for The product of potential difference and water flow rate: Where: e h For components flow;m h is the water flow rate; p T Nodes connected to the component Potential; Δe h Transfer heat to components ,include Loss and heat source load ;Δp T The nodes at both ends of the component potential difference; For large-scale thermal systems, the heat source transfers heat For water supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,S sdiag(p s -p r )m h,S (20) Where: Δe h,S For heat source Column vector; diag(·) represents a diagonal matrix consisting of the elements in the vector; p s and p r They are respectively the supply and return nodes Potential column vector; m h,S is the heat source water flow rate column vector. When the i-th node is the heat source water supply node, m h,S The i-th element of is the water flow rate of this node, and the other elements are 0; the water flow direction from the supply water to the return water node is selected as positive, m h,S and Δe h,S The non-zero elements of are negative; Similarly, the load transfers heat Represented as supply and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,L sdiag(p s -p o )m h,L (21) Where: Δe h,L For load Column vector; p o For the exit node Potential column vector; m h,L is the load water flow rate column vector. When the i-th node is a load water supply node, m h,L The i-th element of is the water flow rate of this node, and the other elements are 0; m h,L and Δe h,L Non-zero elements are positive values; In thermal systems, some load outlet nodes Potential and Return Nodes There is a difference in potential, which generates load Loss, this part Loss is represented by outlet and return nodes The product of the potential difference and the water flow rate is expressed in matrix form as: Δe h,Ll sdiag(p o -p r )m h,L (22) Where: Δe h,Ll For load Loss column vector; The node-branch association matrix is ​​used to describe the thermal system topology. For a large-scale thermal system, the nodes at both ends of the water supply pipe are The potential difference is determined by the node-branch association matrix and the node The potential vector represents the water supply pipeline The loss is expressed as: Where: Δe h,s For water supply pipes Loss vector, n h,p is the number of water supply pipes; m h is the column vector of water flow rate in the water supply pipe; T Represents the transpose of the matrix; A h is the node-branch association matrix of the water supply network; Assuming that the supply network and the return network are completely symmetrical and that water flow losses are ignored, the node-branch association matrix of the return network is considered to be -A h ; Similarly, the return pipe Loss vector Δe h,r It is expressed as: Based on thermal system Flow Mechanism Model, Pipeline The flow is mainly composed of water flowing out of the node in the pipe. The outflow node-branch association matrix and the inflow node-branch association matrix of the water supply network are defined to characterize the topological relationship between the branches and the outflow and inflow nodes; Among them, the water supply network outflow node-branch association matrix A h,- The elements in are represented as: Where: (i, j) represents the element in the i-th row and j-th column of the matrix; Affected by the symmetry of the water supply and return network, the water supply network inflow node-branch association matrix A h,+ That is, the outflow node-branch association matrix of the backwater network, whose elements are: A h,- A h The matrix A is composed of 1 h,+ A h The matrix composed of 1 in , and satisfies: A h =-A h,- +A h,+ (27) Based on the above association matrix, node Potential column vector, water flow rate column vector of water supply pipe, and matrix form to represent water supply and return pipes respectively flow: Where: e h,s and e h,r Water supply and return pipes Flow column vector; Based on the thermal flow, the water flow rate of the water supply network and the water temperature of each node are solved to build the water supply, return water and outlet nodes Potential vector, using equations (3)-(12) to solve the large-scale thermal system Flow distribution; Power System Flow indirect calculation unit, used to calculate the power system Flow mechanism model establishment based on power system flow distribution Stream indirect computation model; Natural gas system Flow indirect calculation unit for natural gas systems Flow Mechanism Modeling for Natural Gas Systems Stream indirect computation model; Energy Station Flow indirect calculation unit for energy stations Flow mechanism model to establish energy station Stream indirect computation model; Integrated Energy Systems Flow indirect calculation unit, used to calculate the power system Flow indirect calculation model, natural gas system Flow indirect computing model, energy station Flow indirect calculation model to solve the thermal system Flow distribution, power system Flow distribution, natural gas systems Flow distribution and equivalent nodes of each energy station loss, and finally obtain the overall integrated energy system Streams and Nodes Potential distribution.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the integrated energy system based on unbalanced node power according to any one of claims 1 to 5 is implemented. Steps of the flow indirect calculation method.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the integrated energy system based on unbalanced node power according to any one of claims 1 to 5 is realized. Steps of the flow indirect calculation method.

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