Multi-source heat supply network topology mapping method based on thermal full equivalence

Abstract

The invention discloses a multi-source heat supply network topology mapping method based on thermodynamic full equivalence, which comprises the following steps: S1, analyzing the heat supply condition of each heat source according to the network topology characteristics of a thermodynamic system, and searching confluence nodes among heat sources and load nodes of non-single heat source heat supply, the method comprises the following steps: S1, recording the mass flow condition of a corresponding confluence pipeline, S2, considering the mass flow proportion rule of the confluence pipeline, decomposing a non-single-heat-source heat supply network area starting from a confluence node, and redistributing the heat load of the part, S3, carrying out resetting of a pipeline thermal resistance and pipeline diameter parameter method of the decomposition area, and S4, carrying out resetting of the pipeline thermal resistance and pipeline diameter parameter method. And obtaining a plurality of single heat source decoupling sub-networks of which the thermal working conditions are completely equivalent to the original multi-source network. According to the method, the characteristics of complex topological structure, large number of heat sources and strong heat supply coupling of the multi-source thermal network are considered, pipeline parameters are set from the confluence node of the thermal network, network equivalent decoupling of the multi-source thermal system is realized, the analysis efficiency of the thermal network is effectively improved, and the analysis cost is reduced. And a powerful guarantee is provided for research on modeling and optimization of the thermodynamic system.

Description

Technical Field

[0001] The present invention belongs to the field of energy system network analysis methods, and specifically relates to a multi-source heat network topology mapping method based on full thermal equivalence. Background Art

[0002] As the global energy crisis and environmental pollution continue to intensify, the energy sector is facing a profound transformation. While the development of new energy systems is accelerating, they still generate significant carbon emissions. Therefore, the comprehensive efficiency of energy utilization urgently needs to be improved to reduce pollutant and carbon dioxide emissions and promote a transition to a low-carbon, clean energy system. Based on the principle of cascaded energy utilization, heating units fully utilize thermal energy of varying grades, resulting in high overall system efficiency. However, as the primary infrastructure for winter heating in northern Chinese cities, heating systems still have significant room for improvement in terms of improving energy efficiency and promoting energy-saving and efficient development in the energy industry.

[0003] However, actual thermal systems cover a wide geographical area and involve numerous heat users and network nodes, making research such as system modeling and optimization complex and time-consuming. At the same time, the topological structure of the thermal system usually presents a complex multi-level network form, including multiple levels such as the backbone network, branch network, and branch network, which greatly increases the difficulty of analysis for scholars. In addition, the heat sources are diverse and widely distributed, and the coordinated operation and load distribution between different heat sources require meticulous management and optimization. The time-varying characteristics of the heat load and the influence of environmental conditions in actual operation, as well as the dynamic response and stability analysis of the system, also increase the complexity of research. How to consider the mutual influence and dynamic coupling effects between heat sources and ensure that the heating conditions of the thermal network before and after decoupling are completely equivalent is the core issue of network decoupling.

[0004] Currently, network analysis of thermal systems is typically performed directly through the modeling and optimization of multi-source networks. When faced with complex multi-source thermal systems, direct modeling and optimization of these networks often involves a large number of variables and constraints, resulting in high computational complexity and considerable solution difficulty. Furthermore, the coupling effects between heat sources can lead to nonlinearities and non-convexities in the model, increasing the challenge of optimization and making it easy to get stuck in local optima. In contrast, decoupling the network into single heat source networks simplifies model complexity while better capturing the characteristics and behavior of each individual heat source network, enabling tailored optimization strategies for each subsystem and improving the accuracy and effectiveness of the overall optimization. Furthermore, by independently optimizing each single heat source network, nonlinearities caused by the coupling effects between heat sources can be effectively avoided, improving the stability and robustness of the solution. Therefore, it is necessary to find methods to decouple the network topology of multi-source thermal systems into equivalent single heat source networks, providing a more efficient solution for thermal system modeling, simulation, and optimization. Summary of the Invention

[0005] Purpose of the invention: In view of the problems in actual network analysis of thermal systems, such as complex topological structures, large numbers of heat sources, strong heat supply coupling, high computational complexity and difficulty in solving direct modeling and optimization of multi-source networks, the present invention considers the actual heating process of each heat source in the thermal system, starts from the confluence node of the thermal network, decomposes the network according to the mass flow ratio of the heat medium in the confluence pipe, and adjusts the pipe parameters to achieve network equivalent decoupling of the multi-source thermal system.

[0006] To achieve the above-mentioned object, the present invention adopts the following technical solution: a multi-source heat network topology mapping method based on full thermal equivalence, the method comprising the following steps: analyzing confluence nodes and confluence pipes, network decomposition and load redistribution, and pipe parameter setting;

[0007] Specifically, first, according to the network topology characteristics of the thermal system, the heating conditions of each heat source are analyzed, the confluence nodes between heat sources and the load nodes that are not heated by a single heat source are found, and the mass flow conditions of the corresponding confluence pipes are recorded.

[0008] Secondly, considering the mass flow rate ratio law of the confluence pipe, the non-single heat source heating network area starting from the confluence node is decomposed, and the heat load of this part is redistributed to achieve the initial decomposition of the heat network.

[0009] Finally, the pipe thermal resistance in the decomposition area and the pipe diameter parameter method are re-adjusted to obtain several single-heat-source decoupled sub-networks whose thermal conditions are completely equivalent to the original multi-source network.

[0010] As an improvement of the present invention, the analysis method of the confluence node and the confluence pipe includes:

[0011] Step 1: Traverse the heating path. Based on the multi-source heating network topology diagram, complete the analysis of the fluid flow direction of the pipe network, take all heat source nodes as the starting point one by one, traverse the network layer by layer in order, and mark all pipes, branches and load points on the heating path of each heat source;

[0012] Step 2: Identify the common heating area. Based on the flow characteristics of the heat medium flow direction, determine the overlapping areas in the heating paths of multiple heat sources, and record the load points in the overlapping areas as non-single heat source heating load nodes;

[0013] Step 3: Locate the confluence node. Using the conservation equation of heat medium flow, clarify the confluence relationship of heat medium in the common heating area. Find the confluence point of heat medium flow in each common heating area (that is, the location where the heat medium first converges), mark it as the confluence node, mark the pipes in the heating path of each heat source that flow to the confluence node, confirm that it is a confluence pipe, and use the flow conservation equation:

[0014]

[0015] Record the corresponding traffic distribution ratio m i / m

[0016] Compared with the existing technology, the present invention has the following beneficial effects: the present invention has significant improvements and advantages in the topology analysis of multi-source heating networks; through the layer-by-layer traversal and marking method of the heating path, starting from the overall topology, the common heating area in the heating network is systematically identified, and the position of the non-single heat source load node is clarified; using the heat medium flow conservation equation, a method for quantitatively locating the confluence node is proposed, combining the flow calculation with the topological analysis, accurately determining the heat medium confluence point, supplemented by the calculation of the flow distribution ratio, to achieve scientific and quantitative analysis; introducing flow direction marking as an auxiliary means, the load nodes in the non-single heat source area are dynamically included in the analysis, making the network decomposition and decoupling more systematic and efficient; from the flow ratio of the confluence node to the distribution scheme of the pipeline and load, combined with clear formulas, it supports the decomposition of the equivalent network of a single heat source; due to its higher versatility and scalability, it provides a theoretical basis for steady-state analysis, dynamic simulation and multi-heat source heating control optimization, with accuracy, efficiency, versatility and foresight, significantly superior to the existing technology, and provides strong support for the research and application of complex multi-source heating networks.

[0017] As an improvement of the present invention, the network decomposition method includes:

[0018] Step 1: Parallel decomposition of pipelines in the common heating area: Based on the aforementioned confluence nodes and non-single heat source areas, a parallel decomposition method is used to decompose all pipelines in any common heating area into two or more identical pipelines, where each pipeline is individually associated with a heat source, forming several single heat source decoupled networks;

[0019] Step 2: Flow Update Rules: Decompose the network into several single-heat-source networks according to the heat supply paths of each heat source. Utilizing the proportional relationship between multiple heat sources in the heat network topology, update the heat medium mass flow data of the pipelines in the shared heating area according to the following rules:

[0020]

[0021] Where m1, m2...m n Indicates that there are n heat sources supplying heat to the heating area, which are the pipe mass flow rates of the corresponding confluence paths; m' represents the initial mass flow rate of a pipe in the common heating area; m i Indicates the mass flow rate of the confluence pipe of the single heat source sub-network where the pipeline is located for the heat source i of the network; m x Represents the updated mass flow rate of the pipeline in the single heat source subnetwork of the xth heat source.

[0022] Compared to existing technologies, this invention offers the following advantages: The network decomposition method, combining parallel decomposition of shared heating areas with dynamic update rules based on flow ratios, achieves precise and dynamic decoupling of complex regions in a multi-source heating network. Compared to existing technologies, this method offers the following improvements and advantages: It precisely decomposes pipelines within shared heating areas, scientifically defining the functional attributes of each pipeline; updates based on flow ratios ensure full equivalence between the original network and the decomposed single-heat-source network; and, with its high accuracy, superior efficiency, and strong adaptability, it provides new theoretical and technical support for the research, optimization, and operation of multi-source heating networks.

[0023] As an improvement of the present invention, the load redistribution method is as follows:

[0024] The heat load values of the non-single heat source heating load nodes in the common heating area covered by the single heat source sub-network are updated according to the following rules, thereby redistributing the load values of the non-single heat source heating load nodes in the network to the corresponding multiple single heat source sub-networks:

[0025]

[0026] Where, φ represents the initial heat load of a non-single heat source heating load node in the common heating area; φ x Indicates the updated heat load value of the node in the single heat source subnetwork of the xth heat source.

[0027] As an improvement of the present invention, the pipeline parameter setting method is:

[0028] Step 1: Based on the single heat source heating characteristics of each pipeline after decoupling, use the following formula to reconfigure the thermal resistance value of some pipelines in the original common heating area in each sub-network after heat source decomposition:

[0029]

[0030] Where, R represents the original thermal resistance of a pipe in the common heating area; R x Represents the updated thermal resistance value of the pipeline in the single heat source subnetwork of the xth heat source.

[0031] Step 2: Based on typical fluid mechanics formulas, update the original pipe diameters of all pipes in the common heating area according to the following rules:

[0032]

[0033] Where D represents the original diameter of a non-pipeline in the common heating area; D x Represents the updated diameter value of the pipe in the single heat source subnetwork of the xth heat source.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0035] The present invention proposes a multi-source heat network topology mapping method based on full thermal equivalence, and provides a scientific and effective network decoupling solution for the problems of a large number of heat sources and complex topological structures in multi-source heat supply systems. The present invention has significant technical advantages in heat network decoupling, multi-heat source optimization, nonlinear solution, heating efficiency improvement, energy utilization optimization, etc. Its scientific decoupling method not only reduces the complexity of the model and simplifies the solution process, but also improves the optimization accuracy, robustness and energy-saving effect in the operation of the heat network; at the same time, theoretical derivation and simulation results prove the wide applicability of this method in complex heat network environments, showing great application potential and practical value. The specific advantages are as follows:

[0036] 1) In a multi-source heat network, due to the cross-heating area and flow coupling relationship between multiple heat sources, the traditional modeling method is overall modeling, which will cause the network complexity to grow exponentially, increase the computational cost and error. The present invention decouples the complex multi-heat source network into several single-heat source sub-networks by introducing a topological mapping method. This method based on "parallel decomposition of pipelines in common heating areas" and "dynamic update of flow" theoretically guarantees the full equivalence of the thermal conditions of the decoupled sub-networks with the original multi-source network (retaining the conservation of mass flow and heat load). For example, each additional heat source in the initial network will introduce n-1 cross-coupling nodes. After the present invention divides it into n independent sub-networks, the structural complexity required for modeling is reduced to a linear level, significantly simplifying the calculation process.

[0037] 2) The optimization problem of multi-source heat networks is usually limited by highly nonlinear problems caused by the coupling effects between multiple heat sources, such as uneven flow distribution, efficiency loss caused by cross-heating of heat sources, and multi-party constraint conflict problems in energy consumption optimization. The present invention decouples the network into single-heat source sub-networks so that each sub-network can be optimized independently, avoiding the complexity of jointly solving the intersection area of multiple heat sources, reducing the dimension of the solution space and the complexity of solving nonlinear problems. Theoretical support shows that the decoupling of the heat network not only reduces the state variables in the decoupling area, but also makes the state transition in the sub-network meet the single-heat source heating characteristics, its distribution parameters are more linear, and the flow distribution can be directly calculated by conservation equations, thereby eliminating unnecessary interactions between heat sources. By avoiding the problem of long-term global search optimization, the independent optimization of each sub-network can utilize local search algorithms to directly and significantly improve the solution stability.

[0038] 3) When the original multi-source heating network is affected by natural fluctuations (such as changes in ambient temperature) and differences in the heating stability of the heat source itself, the heating optimization model of the overall network is prone to unstable solutions and even failure to converge. The present invention decomposes the complex dynamic behavior of the thermal network into multiple independent subsystems through a network topology mapping method. Each subsystem only needs to consider the load allocation of a single heat source, thereby avoiding the uncertainty introduced by global dynamic coupling. For example, the number of variables in the subnetwork is reduced, making the robust optimization algorithm faster and more convergent in the face of disturbances. In addition, the optimization path of each single heat source subnetwork can also be clearer during the optimization process, thereby effectively reducing the risk of fault propagation in the impact of local disturbances on the overall performance of the heating network.

[0039] 4) On the basis of ensuring full thermal equivalence, the present invention dynamically decouples the interaction areas between heat sources and allocates them to a single heat source network, which can better optimize the heating efficiency of the heat source. For example, in a multi-source heating scenario, the decomposed sub-network can be used to more accurately match and regulate the load of a single heat source, avoiding unnecessary vicious competition and repeated heating between heat sources. Test data show that in a typical multi-source heating network scenario, this method can increase the energy utilization rate of the entire heating cycle by 5%-10%, and the energy loss control effect is significant. For example, in a simulation of a certain city's heating transformation, the heat feedback loss (heat loss caused by insufficient return water temperature difference) under the decoupling scheme was reduced by about 8%, and the standard deviation was reduced by 13% compared with the non-decoupling scheme, which significantly improved the heat source stability and energy saving effect.

[0040] 5) The network decomposition and topology mapping method proposed in the present invention has a high degree of theoretical versatility and is applicable to multi-source heat networks of arbitrarily complex structures. Whether it is multiple large heat sources in urban centralized heating networks or renewable energy heat sources (such as geothermal, solar energy, and waste heat recovery) in distributed small-scale heating networks, this solution can adapt to different scenarios through dynamic decomposition and update rules. Especially when faced with multi-center heating systems with nonlinear and complex topologies, this method has shown great advantages. Simulation calculation results show that in the case of 300,000 pipelines, 8 heat sources, and 500 load nodes, the decoupling and decomposition time only accounts for 30% of the modeling time of traditional methods, and the computational complexity is reduced to 40% of the original, and it can be extended to real-time calculations under dynamic conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is an initial network topology diagram of the system according to an embodiment of the present invention;

[0042] Figure 2 This is a topological diagram of a single heat source network after system decoupling in an embodiment of the present invention;

[0043] Figure 3 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0045] Example: Figure 1-Figure 3 As shown, in this embodiment, the 3 heat sources and 35 nodes heat network is decoupled. The parameters of each device do not have a substantial impact on the method proposed by the present invention, so they will not be described here. The pipeline parameters and heating data in the network are as follows:

[0046]

[0047]

[0048]

[0049] According to the system topology, heat sources 1 / 2 / 3 have three common heating areas, each supplied by two heat sources. The labels of the non-single heat source heating load nodes, confluence nodes, and confluence pipes in the common heating areas are summarized as follows:

[0050]

[0051] The mass flow data of the confluence pipe is recorded as follows:

[0052]

[0053] The 35-node network is split from the confluence node. For each single heat source network, all nodes and related pipelines involved in the heat supply of the heat source are retained, and finally three sub-networks are formed, such as Figure 2 shown.

[0054] Based on the mass flow ratio of the converging pipe, the heat medium mass flow data of the common heating pipe in the single heat source sub-network is updated as follows:

[0055]

[0056]

[0057] Similarly, the heat load values of the non-single heat source heating load nodes are redistributed, and the results are as follows:

[0058]

[0059]

[0060] Finally, adjust the pipeline parameters and update the pipeline thermal resistance and pipeline diameter:

[0061]

[0062]

[0063] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above examples. The above examples and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-source heat network topology mapping method based on full thermal equivalence, characterized in that: The following steps are involved: Analyze confluence nodes and confluence pipes, network decomposition and load redistribution, and pipe parameter setting; Specifically, first, according to the network topology characteristics of the thermal system, analyze the heating conditions of each heat source, find the confluence nodes between heat sources and the load nodes that are not heated by a single heat source, and record the mass flow of the corresponding confluence pipes. Secondly, considering the mass flow rate ratio law of the confluence pipe, the non-single heat source heating network area starting from the confluence node is decomposed, and the heat load of this part is redistributed to achieve the initial decomposition of the heat network. Finally, the pipe thermal resistance and pipe diameter parameter method in the decomposition area are readjusted to obtain several single-heat-source decoupled sub-networks whose thermal conditions are completely equivalent to the original multi-source network in both dynamic and steady states.

2. A multi-source heat network topology mapping method based on full thermal equivalence according to claim 1, characterized in that: Analyze confluence nodes and confluence pipes, including: Step 1: Traverse the heating path. Based on the multi-source heating network topology diagram, complete the analysis of the fluid flow direction of the pipe network, take all heat source nodes as the starting point one by one, traverse the network layer by layer in order, and mark all pipes, branches and load points on the heating path of each heat source; Step 2: Identify the common heating area. Based on the flow characteristics of the heat medium flow direction, determine the overlapping areas in the heating paths of multiple heat sources, and record the load points in the overlapping areas as non-single heat source heating load nodes; Step 3: Locate the confluence node. Using the conservation equation of heat medium flow, clarify the confluence relationship of heat medium in the common heating area. Find the confluence point of heat medium flow in each common heating area (that is, the location where the heat medium first converges), mark it as the confluence node, mark the pipes in the heating path of each heat source that flow to the confluence node, confirm that it is a confluence pipe, and use the flow conservation equation: Record the corresponding traffic distribution ratio m i / m.

3. A multi-source heat network topology mapping method based on full thermal equivalence according to claim 1, characterized in that: The network decomposition method comprises: Step 1: Parallel decomposition of pipelines in the common heating area: Based on the aforementioned confluence nodes and non-single heat source areas, a parallel decomposition method is used to decompose all pipelines in any common heating area into two or more identical pipelines, where each pipeline is individually associated with a heat source, forming several single heat source decoupled networks; Step 2: Flow Update Rules: Decompose the network into several single-heat-source networks according to the heat supply paths of each heat source. Utilizing the proportional relationship between multiple heat sources in the heat network topology, update the heat medium mass flow data of the pipelines in the shared heating area according to the following rules: Where m1, m2...m n Indicates that there are n heat sources supplying heat to the heating area, which are the pipe mass flow rates of the corresponding confluence paths; m' represents the initial mass flow rate of a pipe in the common heating area; m i Indicates the mass flow rate of the confluence pipe of the single heat source sub-network where the pipeline is located for the heat source i of the network; m x Represents the mass flow update of the pipeline in the single heat source subnetwork of the xth heat source.

4. A multi-source heat network topology mapping method based on full thermal equivalence according to claim 1, characterized in that: The load redistribution method is: The heat load values of the non-single heat source heating load nodes in the common heating area covered by the single heat source sub-network are updated according to the following rules, thereby redistributing the load values of the non-single heat source heating load nodes in the network to the corresponding multiple single heat source sub-networks: Where, φ represents the initial heat load of a non-single heat source heating load node in the common heating area; φ x Indicates the updated heat load value of the node in the single heat source subnetwork of the xth heat source.

5. A multi-source heat network topology mapping method based on full thermal equivalence according to claim 1, characterized in that: The pipeline parameter setting method is: Step 1: Based on the single heat source heating characteristics of each pipeline after decoupling, use the following formula to reconfigure the thermal resistance value of some pipelines in the original common heating area in each sub-network after heat source decomposition: Where, R represents the original thermal resistance of a pipe in the common heating area; R x Represents the updated thermal resistance value of the pipeline in the single heat source subnetwork of the xth heat source. Step 2: Based on typical fluid mechanics formulas, update the original pipe diameters of all pipes in the common heating area according to the following rules: Where D represents the original diameter of a non-pipeline in the common heating area; D x Represents the updated diameter value of the pipe in the single heat source subnetwork of the xth heat source.

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