A method for calculating energy flow of heat ring network of integrated energy system based on topological decomposition

Abstract

The application discloses a heat power flow calculation method for a thermal ring network in a comprehensive energy system, and mainly comprises the following steps: firstly, according to different known quantities of the nodes of the heat network, the nodes are divided into heat source nodes, heat balance nodes, heat load nodes and intermediate nodes; then, the intermediate nodes are selected for loop breaking, and are decomposed into a primary network and a secondary network; the primary network and the secondary network are alternately iterated until the convergence precision is satisfied; whether the type of the loop breaking node is updated is judged according to the numerical value of the real-time iteration of the heat power of each loop breaking node, and the calculation method is judged according to the type of the node. Compared with the prior art, the method is suitable for a heat network model under quantity regulation; after loop breaking, the heat network can flexibly select to adopt the forward substitution or the Newton-Laplace method according to the current node information, the advantages of ensuring the calculation precision and the fast calculation speed are considered, and the problems of the initial value sensitivity and the high-order Jacobian matrix of the Newton-Laplace method for the heat ring network are avoided.

Description

TECHNICAL FIELD

[0001] The application relates to a high-computational-efficiency heat ring network energy flow calculation method in a comprehensive energy system and belongs to the technical field of comprehensive energy system modeling and simulation. BACKGROUND

[0002] Energy is the basis of social development and human survival. Building a society that saves resources, optimizes energy structure and improves energy utilization rate is the eternal theme of the times. Under this premise, the energy internet emerges as the times require, which strengthens the information transmission between different energies and provides a broader space for the development of comprehensive energy systems.

[0003] The comprehensive energy system realizes coordination of various energies, meets the energy demand of users, improves energy utilization rate, energy supply reliability and safety through scientific scheduling among traditional energy, renewable energy, electricity, cold, heat, gas and the like. At the same time, through the mutual coordination among various energies, the bottleneck of the power transmission and distribution system can be coped with, the equipment utilization rate can be improved, and the updating and reconstruction process of the power generation, transmission and distribution system can be slowed down. In the event of weather or unexpected disasters, the comprehensive energy system can effectively schedule the energy supply of each region and provide strong support for post-fault energy services. Therefore, the comprehensive energy system is praised by the international energy industry as the most possible energy supply and use bearing mode of human society after 30-50 years and has become a hot spot in the international energy field.

[0004] The conventional heat ring network energy flow calculation method of the comprehensive energy system usually adopts the Newton method for calculation, has high nonlinearity, high iteration matrix order and sensitivity to initial values. Therefore, part of the research simplifies the heat network structure through topology decomposition and solves the problem by using the forward-backward substitution algorithm for alternative iteration, but does not discuss in depth and mainly has the following problems: 1. The established calculation model is not applicable to the heat network model of the quantity regulation. 2. The established calculation model is not applicable to the Newton method calculation. 3. The established calculation model does not consider the actual power flow direction of the loop node in the calculation process, which may lead to the node information not meeting the actual node type and easily leading to non-convergence when using the Newton method calculation. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art. The topology decomposition-based comprehensive energy system heat ring network energy flow calculation method can ensure simulation accuracy, reduce solution difficulty and further improve solution speed.

[0006] Technical scheme: To achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A topology decomposition-based comprehensive energy system heat ring network energy flow calculation method, characterized by comprising the following steps:

[0008] (1) According to the different known quantities of nodes, all nodes are divided into four types of nodes: heat balance nodes, known information is heating temperature; heat source nodes, known information is heating temperature and heat power; heat load nodes, known information is heat recovery temperature; intermediate nodes, known information is heat power equal to 0;

[0009] (2) Two intermediate nodes are selected from the heat network topology for loop breaking, which is decomposed into a primary network and a secondary network in a radial structure, and the type information of the loop breaking nodes and the initial value of the power are initialized;

[0010] (3) According to the number of heat source nodes in the secondary network, it is judged whether the secondary network adopts forward-backward substitution calculation or Newton method calculation to solve the energy flow distribution of the secondary network, and the type of the nodes in the secondary network is updated according to the actual power value of the loop breaking nodes, and the heat power and heat recovery temperature of the loop breaking nodes are assigned to the loop breaking nodes of the primary network;

[0011] (4) According to the number of heat source nodes in the primary network, it is judged whether the primary network adopts forward-backward substitution calculation or Newton method calculation to solve the energy flow distribution of the primary network, and the type of the nodes in the primary network is updated according to the actual power value of the loop breaking nodes, and the heating temperature of the loop breaking nodes is assigned to the loop breaking nodes of the secondary network;

[0012] (5) The pipe flow in the energy flow calculation results of steps (3) and (4) is used as the initial value to calculate the pipe flow distribution of the original network through hydraulic calculation, and the power initial value of the loop breaking nodes is updated through the node heat power equation;

[0013] (6) The power error of the loop breaking nodes in steps (2) and (5) is used as the convergence criterion, and the convergence precision is 1e-05, if the convergence precision is not reached, return to step (3); if the convergence precision is reached, output the heat network energy flow calculation result.

[0014] In the step (2), the heat network topology structure is loop broken, and the loop breaking principle and the initial type of the loop breaking nodes are set as:

[0015] Loop breaking principle: the primary network contains the original heat balance nodes of the heat network, and the secondary network does not contain the original heat balance nodes of the heat network, so as to ensure that the number of nodes in the two heat networks after loop breaking is close;

[0016] Initial type of the loop breaking nodes of the primary network: both loop breaking nodes are set as heat load nodes;

[0017] Initial type of the loop breaking nodes of the secondary network: one node is a heat source node, and the other is a heat balance node.

[0018] In the step (3), according to the number of heat source nodes in the secondary network, it is judged whether the secondary network adopts forward-backward substitution calculation or Newton method calculation, which is specifically:

[0019] If the number of heat sources of the secondary network is equal to 1, the forward substitution is used to solve the energy flow of the secondary network;

[0020] If the number of heat sources of the secondary network is greater than 1, the Newton method is used to solve the energy flow of the secondary network.

[0021] In the step (3), the node type of the secondary network is updated according to the actual power value of the loop-breaking node, and specifically:

[0022] If the heat power flow direction of the two loop-breaking nodes is both inflow, one node is selected as a heat source node, and the other is selected as a heat balance node;

[0023] If the heat power flow direction of the two loop-breaking nodes is one inflow and one outflow, the node with inflow is selected as a heat balance node, and the node with outflow is selected as a heat load node;

[0024] If the heat power flow direction of the two loop-breaking nodes is both outflow, both of the two loop-breaking nodes are heat load nodes.

[0025] In the step (4), the forward substitution or the Newton method is used to calculate the energy flow of the primary network according to the number of heat source nodes in the primary network, and specifically:

[0026] If the number of heat sources of the primary network is equal to 1, the forward substitution is used to solve the energy flow of the primary network;

[0027] If the number of heat sources of the primary network is greater than 1, the Newton method is used to solve the energy flow of the primary network.

[0028] In the step (4), the node type of the primary network is updated according to the actual power value of the loop-breaking node, and specifically:

[0029] If the heat power flow direction of the two loop-breaking nodes is both inflow, both of the two loop-breaking nodes are heat source nodes;

[0030] If the heat power flow direction of the two loop-breaking nodes is one inflow and one outflow, the node with inflow is selected as a heat balance node, and the node with outflow is selected as a heat load node;

[0031] If the heat power flow direction of the two loop-breaking nodes is both outflow, both of the two loop-breaking nodes are heat load nodes.

[0032] In the step (5), the pipe segment flow distribution of the original network is calculated by hydraulic calculation, and the node heat power equation is used to update the initial power value of the loop-breaking node, and specifically:

[0033] The hydraulic calculation formula is calculated according to the following formula:

[0034]

[0035] Am=m q

[0036] Bh f = 0

[0037] wherein: m qi is the node i flow, φ i is the node heat load power, C p is the specific heat capacity of water, T si is the node heating temperature, T oi is the node return temperature, m is the pipe flow, m q is the node flow, A is the basic incidence matrix, B is the basic loop matrix, h f is the pipe pressure drop.

[0038] Power update node selection: according to the type selection of the primary main network and the secondary network loop-breaking node, if there is a heat balance node, the heat balance node is selected as the power update node; if there is no heat balance node, a heat source node is selected as the power update node.

[0039] Node heat power update: the node heat power equation is updated according to the result of the hydraulic calculation, and is calculated according to the following formula:

[0040] φ i = C p (T si -T oi )m qi

[0041] wherein: m qi is the node i flow, φ i is the node heat load power, C p is the specific heat capacity of water, T si is the node heating temperature, T oi is the node return temperature.

[0042] Beneficial effects: the comprehensive energy system heat ring network power flow calculation provided by the present application has the following advantages compared with the prior art: 1. The heat ring network topology decomposition method proposed by the present application decomposes the ring network into two radial pipe networks, avoiding the initial value sensitivity problem of the conventional heat ring network directly using the Newton method for calculation; 2. The model established by the present application updates the node type in real time according to the loop-breaking node power value, meets the needs of the existing forward-back substitution and Newton method calculation, and can be directly and flexibly used; 3. The model established by the present application simplifies the order of the Jacobian matrix required for Newton method calculation to a certain extent, and at the same time, part of the calculation process uses the algebraic solution of the forward-back substitution instead of the iterative solution of the Newton method, which guarantees the calculation accuracy while taking into account the advantage of fast calculation speed. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is the implementation flowchart of the method of the present application;

[0044] Figure 2 This is an example diagram of a thermal ring network-like structure for implementing the present invention;

[0045] Figure 3 This is a schematic diagram of the heat network topology decomposition in step (2) of the present invention;

[0046] Figure 4 This is a schematic diagram of selecting the power update node in implementation step (5) of the present invention; Detailed Implementation

[0047] The invention will now be further described with reference to the accompanying drawings.

[0048] The energy flow calculation of the integrated energy system thermal ring network proposed in this invention can maximize the balance between model accuracy and simulation efficiency, while improving the convergence performance of energy flow calculation.

[0049] like Figure 1 The diagram shown is a flowchart of the implementation of the present invention. Figure 2 Taking the simplified structural example diagram as an example, firstly, the heat network nodes are classified according to the known quantities of the nodes; secondly, two intermediate nodes are selected for loop unblocking, and the initial node types are set as follows. Figure 3 As shown; then, based on the number of heat sources in the two radial pipe networks, the forward-backward substitution or Newton-Raphson method is selected, and the node type is updated in real time according to the thermal power values ​​at the solution nodes; then, the thermal power at the solution nodes is updated through hydraulic calculations, and the node selection for thermal power updates is as follows. Figure 4 As shown; repeat the above steps until the convergence accuracy is met, specifically including the following steps:

[0050] (1) Based on the different known quantities of the nodes, all nodes are divided into four categories: heat balance nodes, with the known information being the heating temperature; heat source nodes, with the known information being the heating temperature and heat power; heat load nodes, with the known information being the regeneration temperature; and intermediate nodes, with the known information being that the heat power is equal to 0.

[0051] (2) Select two intermediate nodes from the heat network topology to de-loop, decompose them into a radial structure of primary main network and secondary secondary network, and initialize the de-loop node type information and initial power value;

[0052] (3) Based on the number of heat source nodes in the secondary subnet, determine whether the secondary subnet is calculated using forward-backward substitution or Newton-Laurent method, solve the energy flow distribution of the secondary subnet, update the node type of the secondary subnet according to the actual power value of the solution node, and assign the heat power and regeneration temperature of the solution node to the solution node of the primary main network.

[0053] (4) According to the number of heat source nodes in the primary main network, it is judged whether the primary main network adopts the forward-backward substitution calculation or the Newton-Raphson method calculation to solve the energy flow distribution of the primary main network, and the actual power value of the loop-breaking node is used to update the node type of the primary main network, and the heating temperature of the loop-breaking node is assigned to the loop-breaking node of the secondary network;

[0054] (5) The pipe section flow in the energy flow calculation results of steps (3) and (4) is used as the initial value to calculate the pipe section flow distribution of the original network through hydraulic calculation, and the power initial value of the loop-breaking node is updated through the node heat power equation;

[0055] (6) The power error of the loop-breaking node in steps (2) and (5) is used as the convergence criterion, the convergence precision is 1e-05, if the convergence precision is not reached, return to step (3); if the convergence precision is reached, output the heat network energy flow calculation result.

[0056] In the step (2), the heat network topology structure is loop broken, and the loop breaking principle and the initial type of the loop-breaking node are set as:

[0057] Loop breaking principle: the primary main network contains the original heat network heat balance node, and the secondary network does not contain the original heat network heat balance node, so as to ensure that the number of nodes in the two heat networks after loop breaking is close;

[0058] Initial type of the loop-breaking node of the primary main network: both loop-breaking nodes are set as heat load nodes;

[0059] Initial type of the loop-breaking node of the secondary network: one node is a heat source node, and the other is a heat balance node.

[0060] In the step (3), according to the number of heat source nodes in the secondary network, it is judged whether the secondary network adopts the forward-backward substitution calculation or the Newton-Raphson method calculation, specifically:

[0061] If the number of heat sources in the secondary network is equal to 1, the forward-backward substitution is used to solve the energy flow of the secondary network;

[0062] If the number of heat sources in the secondary network is greater than 1, the Newton-Raphson method is used to solve the energy flow of the secondary network.

[0063] In the step (3), the actual power value of the loop-breaking node is used to update the node type of the secondary network, specifically:

[0064] ① If the heat power flow directions of the two loop-breaking nodes are both inflow, one node is selected as a heat source node, and the other is selected as a heat balance node;

[0065] ② If the heat power flow directions of the two loop-breaking nodes are one inflow and one outflow, the node with inflow power is selected as a heat balance node, and the node with outflow power is selected as a heat load node;

[0066] ③ If the two loop-breaking nodes are both heat load nodes, the heat power flow direction of the two loop-breaking nodes is both outflow.

[0067] In the step (4), according to the number of heat source nodes in the primary secondary network, it is determined whether the primary secondary network adopts the forward-backward substitution calculation or the Newton method calculation, and the specific steps are as follows:

[0068] If the number of heat sources in the primary secondary network is equal to 1, the forward-backward substitution is used to solve the energy flow of the primary secondary network.

[0069] If the number of heat sources in the primary secondary network is greater than 1, the Newton method is used to solve the energy flow of the primary secondary network.

[0070] In the step (4), the node type of the primary main network is updated according to the actual power value of the loop-breaking node, and the specific steps are as follows:

[0071] ① If the two loop-breaking nodes are both heat source nodes, the heat power flow direction of the two loop-breaking nodes is both inflow.

[0072] ② If the heat power flow direction of the two loop-breaking nodes is one inflow and one outflow, the node with inflow is selected as the heat balance node, and the node with outflow is selected as the heat load node.

[0073] ③ If the heat power flow direction of the two loop-breaking nodes is both outflow, the two loop-breaking nodes are both heat load nodes.

[0074] In the step (5), the pipe section flow distribution of the hydraulic calculation original network is calculated, and the node heat power equation is updated to obtain the initial value of the power of the loop-breaking node, and the specific steps are as follows:

[0075] The hydraulic calculation formula is calculated according to the following formula:

[0076]

[0077] Am=m q

[0078] Bh f =0

[0079] Wherein: m qi is the flow of node i, φ i is the heat load power of node, C p is the specific heat capacity of water, T si is the heating temperature of node, T oi is the return temperature of node, m is the pipe flow, m q is the node flow, A is the basic incidence matrix, B is the basic loop matrix, h f is the pipe pressure drop.

[0080] Power update node selection: according to the type selection of the primary main network and the secondary network loop node, if there is a thermal balance node, the thermal balance node is used as the power update node; if there is no thermal balance node, a heat source node is selected as the power update node.

[0081] Node thermal power update: according to the result of the hydraulic calculation, the node thermal power equation is updated, and the following formula is used for calculation:

[0082] φ i =C p (T si -T oi )m qi

[0083] Wherein: m qi is the flow of node i, φ i is the node thermal load power, C p is the specific heat capacity of water, T si is the heating temperature of the node, and T oi is the return temperature of the node.

[0084] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method for calculating energy flow in a thermal loop network of an integrated energy system based on topological decomposition, characterized in that: Includes the following steps: (1) Based on the different known quantities of the nodes, all nodes are divided into four categories: heat balance nodes, with the known information being the heating temperature; heat source nodes, with the known information being the heating temperature and heat power; heat load nodes, with the known information being the regeneration temperature; and intermediate nodes, with the known information being that the heat power is equal to 0. (2) Select two intermediate nodes from the heat network topology to de-loop, decompose into a radial structure of primary main network and secondary secondary network, and initialize the de-loop node type information and initial power value; (3) Based on the number of heat source nodes in the secondary subnet, determine whether the secondary subnet is calculated by forward substitution or Newton-Laurent method, solve the energy flow distribution of the secondary subnet, update the node type of the secondary subnet according to the actual power value of the solution node, and assign the heat power and regeneration temperature of the solution node to the solution node of the primary main network. (4) Based on the number of heat source nodes in the primary main network, determine whether the primary main network is calculated by forward pushback or Newton-Laurel method, solve the energy flow distribution of the primary main network, update the node type of the primary main network according to the actual power value of the solution node, and assign the heating temperature of the solution node to the solution node of the secondary network. (5) The pipe flow rate in the energy flow calculation results of steps (3) and (4) is used as the initial value. The pipe flow rate distribution of the original network is calculated by hydraulic calculation, and the initial power value of the solution node is updated by the node thermal power equation. In step (5), the hydraulic calculation of the pipe segment flow distribution of the original network and the updating of the initial power values ​​of the node nodes in the solution process are as follows: Hydraulic calculations are performed according to the following formula: ， in: For node i traffic, For node heat load power, The specific heat capacity of water, The heating temperature of the node. The returned temperature of the node. For pipeline flow rate, For node traffic, For the basic correlation matrix, For the basic loop matrix, For pipeline pressure drop, Power update node selection: The selection is based on the type of node in the primary main network and the secondary sub-network. If a thermal balance node exists, it is selected as the power update node; otherwise, a heat source node is selected as the power update node. Nodal thermal power update: Update the nodal thermal power equations based on the results of hydraulic calculations, according to the following formula: ， in: For node i traffic, For node heat load power, The specific heat capacity of water, The heating temperature of the node. The returned temperature of the node; (6) The power error of the solution node in steps (2) and (5) is used as the convergence criterion. The convergence accuracy is 1e-05. If the convergence accuracy is not reached, return to step (3); if the convergence accuracy is reached, output the heat network energy flow calculation result.

2. The method for calculating energy flow in a thermal ring network of a comprehensive energy system based on topological decomposition according to claim 1, characterized in that: In step (2), the heat network topology is de-looped. The de-looping principle and the initial type of the de-looping point are set as follows: Loop-breaking principle: The network that includes the original heat balance node is the primary network, and the network that does not include the original heat balance node is the secondary network, so as to ensure that the number of nodes in the two heat networks is close after the loop is broken. Initial type of primary main network solution nodes: Both solution nodes are set as hot load nodes; The initial type of nodes in the secondary sub-network is: one node is a heat source node, and the other is a heat balance node.

3. The method for calculating energy flow in a thermal loop network of a comprehensive energy system based on topological decomposition according to claim 1, characterized in that: In step (3), based on the number of heat source nodes in the secondary subnet, it is determined whether the secondary subnet is calculated using forward-backward substitution or the Newton-Laurel method. Specifically: If the number of heat sources in the secondary subgrid is equal to 1, the energy flow of the secondary subgrid is solved by forward substitution and backward substitution. If the number of heat sources in the secondary network is greater than 1, the Newton-Layer method is used to solve for the energy flow of the secondary network.

4. The method for calculating energy flow in a thermal ring network of a comprehensive energy system based on topological decomposition according to claim 1, characterized in that: In step (3), the type of the secondary subnet node is updated according to the actual power value of the solution node, specifically as follows: ① If the heat power flow direction of both solution nodes is inflow, select one node as the heat source node and the other as the heat balance node; ② If the heat power flow direction of the two solution nodes is one inflow and one outflow, select the node with power inflow as the heat balance node and select the node with power outflow as the heat load node. ③ If the heat power flow direction of both solution nodes is outflow, then both solution nodes are heat load nodes.

5. The method for calculating energy flow in a thermal loop network of a comprehensive energy system based on topological decomposition according to claim 1, characterized in that: In step (4), based on the number of heat source nodes in the primary network, it is determined whether the primary network is calculated using forward-backward substitution or the Newton-Laurel method. Specifically: If the number of heat sources in the primary network is equal to 1, the energy flow of the primary network is solved by forward substitution and backward substitution. If the number of heat sources in the primary network is greater than 1, the Newton-Layer method is used to solve for the energy flow of the primary network.

6. The method for calculating energy flow in a thermal ring network of a comprehensive energy system based on topological decomposition according to claim 1, characterized in that: In step (4), the primary main network node type is updated according to the actual power value of the node being resolved, specifically as follows: ① If the heat power flow direction of both solution nodes is inflow, then both solution nodes are heat source nodes; ② If the heat power flow direction of the two solution nodes is one inflow and one outflow, select the node with power inflow as the heat balance node and select the node with power outflow as the heat load node. ③ If the heat power flow direction of both solution nodes is outflow, then both solution nodes are heat load nodes.

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