CN112257281A - Dynamic energy flow calculation method for two-stage quality regulation hot water heating network - Google Patents

Dynamic energy flow calculation method for two-stage quality regulation hot water heating network Download PDF

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CN112257281A
CN112257281A CN202011181460.0A CN202011181460A CN112257281A CN 112257281 A CN112257281 A CN 112257281A CN 202011181460 A CN202011181460 A CN 202011181460A CN 112257281 A CN112257281 A CN 112257281A
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heat
network
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stage
temperature
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顾伟
姚帅
张苏涵
陆帅
周苏洋
吴志
陈晓刚
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Southeast University
State Grid Zhejiang Electric Power Co Ltd
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State Grid Zhejiang Electric Power Co Ltd
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Abstract

The invention discloses a method for calculating dynamic energy flow of a two-stage quality-adjusting hot water heating network, which comprises the following steps: establishing a dynamic energy flow calculation model of a mass-regulation heat supply network, dividing an energy flow calculation process into two stages, and determining the known quantity and the quantity to be obtained in each stage; presetting initial values of water supply temperature at all output fixed heat sources, and obtaining a network dynamic energy flow initial result through a first-stage iterative algorithm; calculating output updating values of all output adjustable heat source units based on the preliminary result and the minimum adjustable interval of the heat source units; and based on the output update value, obtaining a final result of the network dynamic energy flow through a second-stage iterative algorithm. The method adopts the heat supply network dynamic model, can acquire the dynamic change process of the heat supply network state, provides theoretical support for planning, safety analysis and operation scheduling of the heat supply network, introduces the minimum adjustment interval limit of a heat source, and corrects the energy flow calculation result through the second-stage algorithm, thereby acquiring more accurate heat supply network state information.

Description

Dynamic energy flow calculation method for two-stage quality regulation hot water heating network
Technical Field
The invention belongs to the technical field of energy system simulation methods, and particularly relates to a dynamic energy flow calculation method for a two-stage quality-adjusting hot water heating network.
Background
The traditional energy system is mainly operated in a discrete mode, and most mainstream energy systems such as coal, petroleum, natural gas, electric power and cooling/heating systems are operated respectively, so that a closed industry and interest barrier are formed. Due to the barriers, the mutual complementary interaction characteristic and the cascade utilization potential of various energy sources cannot be exerted, so that the comprehensive utilization efficiency of the energy sources is reduced, the carbon emission is increased to a certain extent, and the problem of environmental pollution is aggravated.
Under the background that the world Energy System is in urgent need of transformation and upgrading, the concept of Integrated Energy System (IES) is widely supported by academia and industry. The comprehensive energy system can break the discrete operation barriers of the traditional energy system, fully exerts complementary interaction characteristics and cascade utilization potential among various forms of energy (including coal, petroleum, natural gas, electric power, heat/cold, wind, light, water, hydrogen and the like), thereby improving the comprehensive energy efficiency of the energy system, reducing carbon emission and pollutant emission, improving the stability and reliability of the energy supply system, and promoting the absorption of renewable energy, and has bright development prospect.
The hot water heating network is an important component of a comprehensive energy system, can transfer heat energy to heat loads (heating, ventilation, domestic hot water and the like) through hot water, and is a key link in a civil heating system. The energy flow calculation of the hot water heating pipe network can guide and plan the capacity, the access point and the grid structure of various heat source equipment in the planning stage, guide each equipment to adjust the output in the operation stage, meet the load demand, and also can acquire the operation state of the system, thereby having important significance for the safety analysis of the system.
There are two typical operating modes of a hot water heating network: quality regulation and quantity regulation. The former realizes heat supply regulation by changing the water supply temperature of a heat source (without changing the flow rate of hot water in a network); the latter realizes heating regulation by changing the flow rate of hot water in the network (without changing the water supply temperature of the heat source). The problem of calculating the energy flow of the heat supply network refers to how to obtain the state information of the whole network through a mathematical model of the heat supply network under the given conditions of a known part, wherein the state information comprises the water temperature distribution in the network, the power output at a heat source and the like.
Energy flow calculation research for a quality-adjusting hot water pipe network is mostly based on a steady-state heat supply network model, the dynamic change process of water temperature in the pipe network cannot be obtained, and the steady-state model is low in precision, so that the calculation result is prone to having large deviation from the actual situation. In addition, the conventional energy flow calculation research does not consider the output regulation limitation of the heat source unit, namely, the influence of the thermal inertia of equipment such as a boiler and the physical constraints of actuating mechanisms such as a pump and a valve on the frequent regulation of the heat source unit, so that the result of the energy flow calculation is too ideal and has a certain deviation from the actual state of the system.
Disclosure of Invention
The invention provides a method for calculating dynamic energy flow of a two-stage quality-adjusting hot water heating network aiming at the problems in the prior art. Firstly, establishing a dynamic energy flow calculation model of a hot water heating network in a quality regulation operation mode, dividing an energy flow calculation process into two stages, and determining the known quantity and the quantity to be calculated of each stage model; secondly, setting initial values of water supply temperature at all output fixed heat sources, and solving an initial result of the network dynamic energy flow through a first-stage iterative algorithm; then, based on the initial result of the dynamic energy flow in the first stage and the minimum adjustable interval of the heat source unit, calculating output updated values of all the output adjustable heat source units, and taking the output updated values as input quantity of a second-stage energy flow calculation model; and finally, based on the output update values of all the output-adjustable heat source units, obtaining the final result of the network dynamic energy flow through a second-stage iterative algorithm. The method adopts the heat supply network dynamic model, can acquire the dynamic change process of the heat supply network state, and provides theoretical support for planning, safety analysis and operation scheduling of the heat supply network. In addition, the method considers the minimum regulation interval limit introduced by the thermal inertia of the heat source unit and the physical constraint of the actuating mechanism when the output of the heat source unit is regulated, and corrects the energy flow calculation result through the second-stage algorithm, so that more accurate heat supply network state information can be obtained.
In order to achieve the purpose, the invention adopts the technical scheme that: a dynamic energy flow calculation method for a two-stage quality regulation hot water heating network comprises the following steps:
s1, establishing a dynamic energy flow calculation model of the hot water heating network in a quality regulation operation mode, dividing an energy flow calculation process into two stages, and determining the known quantity and the quantity to be obtained of each stage model;
s2, setting initial values of water supply temperature at all output fixed heat sources, and obtaining an initial result of the network dynamic energy flow through a first-stage iterative algorithm;
s3, calculating output updated values of all output adjustable heat source units based on the initial result of the dynamic energy flow in the step S2 and the minimum adjustable interval of the heat source units, and taking the output updated values as input flow of the second-stage energy flow calculation model;
and S4, based on the output update values of all the output adjustable heat source units obtained in the step S3, obtaining the final result of the network dynamic energy flow through a second-stage iterative algorithm.
As an improvement of the present invention, in step S1, the dynamic simulation model of the heat supply network is:
Figure BDA0002750309630000031
in the formula: t and TeRespectively representing the temperature of a heating medium in the pipeline and the temperature of the environment outside the pipeline; f. q and c respectively represent the flow rate, flow and specific heat capacity of the heating medium; r is the thermal resistance of the pipeline; t and x represent temporal and spatial variables, respectively; e represents the set of all branches in the heat network;
Figure BDA0002750309630000032
and
Figure BDA0002750309630000033
respectively representing the flow of heat medium flowing into the node n from the node k and the flow of heat medium flowing out of the node n to the node k; v represents the set of all nodes of the heat supply network;
Figure BDA0002750309630000034
and
Figure BDA0002750309630000035
all branch sets respectively representing the hot medium inflow and outflow nodes n;
Figure BDA0002750309630000036
the terminal temperature of the k-th pipeline with the heating medium flowing into the node n is shown; t isnRepresents the temperature of the heating medium at node n;
Figure BDA0002750309630000037
the head end temperature of the k-th pipeline with the heat medium flowing out of the node n is shown; phi is akRepresents the thermal power contained by node k or branch k;
Figure BDA0002750309630000038
and
Figure BDA0002750309630000039
respectively representing the supply water temperature and the return water temperature of the node k or the branch k.
As another improvement of the present invention, in step S1, the energy flow calculation process is divided into two stages, and the known quantities of the first stage model are:
1) injection at all imposed fixed heat sourcesThermal power phik(k∈Vs-f)
2) Water supply temperature at all output adjustable heat sources
Figure BDA0002750309630000041
3) Heat output power phi at all thermal loadsk(k∈Vl)
4) Flow q of hot water in each pipek(k∈E)
5) Initial value of supply and return water temperature of heat supply network
Figure BDA0002750309630000042
6) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline
Wherein: vs-1Representing a set of all heat source nodes with fixed output thermal power; vsRepresenting the set of all heat source nodes with adjustable output thermal power; vlRepresenting a set of all load nodes;
the quantities to be solved for the first stage model are:
1) water supply temperature at all output fixed heat sources
Figure BDA0002750309630000043
2) Injected thermal power phi of all the power adjustable heat sourcesk(k∈Vs-a)
3) Water temperature distribution in heat network at any time
Figure BDA0002750309630000044
As another improvement of the present invention, in step S1, the partial differential equation describing the temperature dynamics of the heat supply network is discretized by using the following differential format:
Figure BDA0002750309630000045
in the formula: t represents the temperature of the heat medium in the heat supply network; i, k and jRespectively representing the index of the number of segments of the pipeline, the time index and the index of the pipeline in the heat supply network, Ti k+1The temperature of the heating medium at the ith section of a certain pipeline in the heat supply network at the moment k +1 is represented; mjAnd NjRespectively representing the number of space segments and the number of time segments of the jth pipe section; alpha is alphajAnd betajAre two parameters defined:
Figure BDA0002750309630000051
in the formula: f. ofjAnd q isjRespectively representing the flow speed and the flow of the heating medium in the jth pipeline at the k moment; h isjAnd τjRespectively representing the spatial difference step size and the time difference step size of the jth pipeline.
As another improvement of the present invention, in step S1, the known quantities of the second-stage power flow calculation model are:
1) injected thermal power phi at all heat sourcesk(k∈Vs)
2) Heat output power phi at all thermal loadsk(k∈Vl)
3) Flow q of hot water in each pipek(k∈E)
4) Initial value of supply and return water temperature of heat supply network
Figure BDA0002750309630000052
5) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline
The quantity to be solved of the second stage model is as follows: water temperature distribution in heat network at any time
Figure BDA0002750309630000053
As another improvement of the present invention, in the step S2, initial values of the supply water temperature at all the output fixed heat sources are set, and the initial result of the network dynamic power flow is obtained through a first-stage iterative algorithm, and the step S2 further includes:
s21, inputting the first stage power flow calculationAll known quantities of the model: phi is ak(k∈Vs-f)、
Figure BDA0002750309630000054
φk(k∈Vl)、qk(k∈E)、
Figure BDA0002750309630000055
G (V, E) and Θ (E);
s22, setting the initial values of the water supply temperature at all the positions of the output fixed heat sources
Figure BDA0002750309630000056
S23, adjusting the temperature of the water supply at the heat source by all known output forces
Figure BDA0002750309630000057
Flow q of hot water in each water supply pipek(k∈Es) Initial value of water supply temperature of heat supply network
Figure BDA0002750309630000058
And the initial values of the water supply temperatures of all the output fixed heat sources
Figure BDA0002750309630000059
Calculating the temperature distribution of the whole network water supply through the formula (4)
Figure BDA00027503096300000510
Wherein EsRepresenting the collection of all pipes in the water supply network;
Figure BDA0002750309630000061
s24, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S23
Figure BDA0002750309630000062
Calculating the return water temperature of all the loads by the formula (5)Degree of rotation
Figure BDA0002750309630000063
Figure BDA0002750309630000064
S25, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure BDA0002750309630000065
And the return water temperatures at all the loads determined in step S24
Figure BDA0002750309630000066
Calculating the temperature distribution of the return water of the whole network by the formula (6)
Figure BDA0002750309630000067
Wherein ErRepresenting the set of all pipelines in the water return pipe network;
Figure BDA0002750309630000068
s26, fixing the injected thermal power phi at the heat source by all known output forcesk(k∈Vs-f) And the temperature distribution of the return water of the whole network obtained in the step S25
Figure BDA0002750309630000069
Calculating the water supply temperature update values of all the output fixed heat sources through the formula (7)
Figure BDA00027503096300000610
Figure BDA00027503096300000611
S27, comparing the maximum value of the water supply temperature deviation at all the output fixed heat sources before and after updating
Figure BDA00027503096300000612
And the allowed convergence error err, where k ∈ Vs-f：
If it is
Figure BDA00027503096300000613
Then according to
Figure BDA00027503096300000614
Correcting the water supply temperature of all the output fixed heat sources, and returning to the step S23 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S28 is switched to;
s28, ending the iterative process, and outputting all the quantities to be solved of the first-stage energy flow calculation model:
Figure BDA0002750309630000071
φk(k∈Vs-a) And Tk(k ∈ E), wherein:
Figure BDA0002750309630000072
as a further improvement of the present invention, in step S3, based on the preliminary dynamic power flow results calculated in step S2 and the minimum adjustable interval of the heat source units, output updated values of all the output-adjustable heat source units are calculated and used as input flows of the second-stage power flow calculation model. The output update values of all the output adjustable heat source units are as follows:
Figure BDA0002750309630000073
in the formula:
Figure BDA0002750309630000074
representing the output updated value of the kth output adjustable heat source unit in the ith adjusting period;
Figure BDA0002750309630000075
the duration of each adjustment period is represented and must be smaller than the minimum adjustable interval of the unit; t is t0Representing an initial point in time of the fluence calculation; phi is akiRepresenting the output value of the kth output-adjustable heat source unit in the ith adjusting period obtained by the first-stage energy flow calculation;
Figure BDA0002750309630000076
a set of indices representing all adjustment periods.
As another improvement of the present invention, in the step S4, based on the updated values of output of all the output-adjustable heat source units obtained in the step S3, the final result of the network dynamic power flow is obtained through a second-stage iterative algorithm, and the step S4 further includes:
s41, inputting all known quantities of the second stage power flow calculation model: phi is ak(k∈Vs)、φk(k∈Vl)、qk(k∈E)、
Figure BDA0002750309630000077
G (V, E) and Θ (E);
s42, setting the output values of all the heat source units with adjustable output as
Figure BDA0002750309630000078
The water supply temperatures of all heat sources in the first-stage energy flow calculation result are used as initial values of the water supply temperatures of the heat sources in the second-stage energy flow calculation
Figure BDA0002750309630000079
S43, the flow rate q of hot water in each water supply pipeline is knownk(k∈Es) Initial value of water supply temperature of heat supply network
Figure BDA0002750309630000081
And the initial value of the water supply temperature of all heat sources
Figure BDA0002750309630000082
Calculating the temperature distribution of the whole network water supply through the formula (4)
Figure BDA0002750309630000083
S44, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S43
Figure BDA0002750309630000084
Calculating the return water temperature at all the loads by the formula (5)
Figure BDA0002750309630000085
S45, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure BDA0002750309630000086
And the return water temperatures at all the loads determined in step S44
Figure BDA0002750309630000087
Calculating the temperature distribution of the return water of the whole network by the formula (6)
Figure BDA0002750309630000088
S46, injecting heat power phi from all known heat sourcesk(k∈Vs) And the temperature distribution of the return water of the whole network obtained in the step S45
Figure BDA0002750309630000089
Calculating the supply water temperature update values at all heat sources by equation (7)
Figure BDA00027503096300000810
S47, comparing the maximum value of the water supply temperature deviation at all heat sources before and after updating
Figure BDA00027503096300000811
And the allowed convergence error err, where k ∈ Vs：
If it is
Figure BDA00027503096300000812
Then according to
Figure BDA00027503096300000813
Correcting the water supply temperature of all heat sources, and returning to the step S43 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S48 is switched to;
s48, ending the iterative process, and outputting all the quantities to be solved of the second-stage energy flow calculation model:
Figure BDA00027503096300000814
therefore, the final dynamic energy flow result of the quality-adjusting hot water pipe network can be obtained.
Advantageous effects
Compared with the prior art, the dynamic energy flow calculation method for the two-stage quality-adjusting hot water heating network provided by the invention adopts the dynamic model of the heat supply network, can obtain the dynamic change process of the state of the heat supply network, and provides theoretical support for planning, safety analysis and operation scheduling of the heat supply network. In addition, the method considers the minimum regulation interval limit introduced by the thermal inertia of the heat source unit and the physical constraint of the actuating mechanism when the output of the heat source unit is regulated, and corrects the energy flow calculation result through the second-stage algorithm, so that more accurate heat supply network state information can be obtained.
Drawings
FIG. 1 is a flow chart of the steps of the method of the present invention;
FIG. 2 is a schematic view of a heat network according to an embodiment of the present invention;
FIG. 3 is a graph showing the variation of heating power taken at a load in an embodiment of the present invention;
FIG. 4 is a graph illustrating the variation of injected thermal power at a heat source in an embodiment of the present invention;
FIG. 5 is a graph showing the temperature change of the supplied water at the heat source in the embodiment of the present invention;
FIG. 6 is a graph of water temperature changes at the water supply network nodes 10, 18 and 26 in accordance with an embodiment of the present invention;
FIG. 7 is a graph showing the water temperature changes at the nodes 5, 25 and 34 of the water return network in the embodiment of the invention.
Detailed Description
The invention will be described in more detail below with reference to the accompanying figures 1-7 and examples.
Example 1
The method for calculating the dynamic energy flow of the two-stage quality-control hot water heating network, as shown in fig. 1, comprises the following steps:
s1, the hot water heating network is in a quality adjustment operation mode, namely the flow of each branch is kept unchanged, and the dynamic energy flow calculation model is as follows:
Figure BDA0002750309630000091
in the formula: t and TeRespectively representing the temperature of a heating medium in the pipeline and the temperature of the environment outside the pipeline; f. q and c respectively represent the flow rate, flow and specific heat capacity of the heating medium; r is the thermal resistance of the pipeline; t and x represent temporal and spatial variables, respectively; e represents the set of all branches in the heat network;
Figure BDA0002750309630000101
and
Figure BDA0002750309630000102
respectively representing the flow of heat medium flowing into the node n from the node k and the flow of heat medium flowing out of the node n to the node k; v represents the set of all nodes of the heat supply network;
Figure BDA0002750309630000103
and
Figure BDA0002750309630000104
all branch sets respectively representing the hot medium inflow and outflow nodes n;
Figure BDA0002750309630000105
indicating the kth hot media streamEntering the pipeline end temperature of the node n; t isnRepresents the temperature of the heating medium at node n;
Figure BDA0002750309630000106
the head end temperature of the k-th pipeline with the heat medium flowing out of the node n is shown; phi is akRepresents the thermal power contained by node k or branch k;
Figure BDA0002750309630000107
and
Figure BDA0002750309630000108
respectively representing the supply water temperature and the return water temperature of the node k or the branch k.
The partial differential equation describing the temperature dynamics of the heat supply network is discretized by adopting the following differential format:
Figure BDA0002750309630000109
in the formula: t represents the temperature of the heat medium in the heat supply network; i, k and j represent index of segment number of pipeline, time index and pipeline index in heat supply network respectively, Ti k+1The temperature of the heating medium at the ith section of a certain pipeline in the heat supply network at the moment k +1 is represented; mjAnd NjRespectively representing the number of space segments and the number of time segments of the jth pipe section; alpha is alphajAnd betajAre two parameters defined:
Figure BDA00027503096300001010
in the formula: f. ofjAnd q isjRespectively representing the flow speed and the flow of the heating medium in the jth pipeline at the k moment; h isjAnd τjThe spatial difference step and the temporal difference step of the jth pipe are respectively shown, and the spatial difference step and the temporal difference step are respectively 40 meters and 60 seconds in the embodiment.
As shown in fig. 2, in the present embodiment, the heat supply network includes 3 heat sources, 21 heat loads, and 35 pipes, where heat source #2 is a balance node, and the known quantities of the first-stage dynamic power flow calculation model are:
1) injected thermal power phi of all the output fixed heat sourcesk(k∈Vs-f)
2) Water supply temperature at all output adjustable heat sources
Figure BDA00027503096300001011
3) Heat output power phi at all thermal loadsk(k∈Vl)
4) Flow q of hot water in each pipek(k∈E)
5) Initial value of supply and return water temperature of heat supply network
Figure BDA0002750309630000111
6) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline
Wherein: vs-1Representing a set of all heat source nodes with fixed output thermal power; vsRepresenting the set of all heat source nodes with adjustable output thermal power; vlRepresenting a set of all load nodes;
the quantities to be solved for the first stage model are:
1) water supply temperature at all output fixed heat sources
Figure BDA0002750309630000112
2) Injected thermal power phi of all the power adjustable heat sourcesk(k∈Vs-a)
3) Water temperature distribution in heat network at any time
Figure BDA0002750309630000113
The known quantities of the second stage dynamic energy flow calculation model are:
1) injected thermal power phi at all heat sourcesk(k∈Vs)
2) Heat output power phi at all thermal loadsk(k∈Vl)
3) Flow q of hot water in each pipek(k∈E)
4) Initial value of supply and return water temperature of heat supply network
Figure BDA0002750309630000114
5) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline
The quantity to be solved of the second stage model is as follows: water temperature distribution in heat network at any time
Figure BDA0002750309630000115
S2, setting initial values of water supply temperature at all the output fixed heat sources, and obtaining an initial result of the network dynamic energy flow through a first-stage iterative algorithm, wherein the method specifically comprises the following steps:
s21, inputting all known quantities of the first-stage power flow calculation model: phi is ak(k∈Vs-f)、
Figure BDA0002750309630000116
φk(k∈Vl)、qk(k∈E)、
Figure BDA0002750309630000117
G (V, E) and Θ (E);
s22, setting the initial values of the water supply temperature at all the positions of the output fixed heat sources
Figure BDA0002750309630000118
S23, adjusting the temperature of the water supply at the heat source by all known output forces
Figure BDA0002750309630000119
Flow q of hot water in each water supply pipek(k∈Es) Initial value of water supply temperature of heat supply network
Figure BDA00027503096300001110
And the initial values of the water supply temperatures of all the output fixed heat sources
Figure BDA0002750309630000121
Calculating the temperature distribution of the whole network water supply through the formula (4)
Figure BDA0002750309630000122
Wherein EsRepresenting the collection of all pipes in the water supply network;
Figure BDA0002750309630000123
s24, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S23
Figure BDA0002750309630000124
Calculating the return water temperature at all the loads by the formula (5)
Figure BDA0002750309630000125
Figure BDA0002750309630000126
S25, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure BDA0002750309630000127
And the return water temperatures at all the loads determined in step S24
Figure BDA0002750309630000128
Calculating the temperature distribution of the return water of the whole network by the formula (6)
Figure BDA0002750309630000129
Wherein ErRepresenting the set of all pipelines in the water return pipe network;
Figure BDA00027503096300001210
s26, fixing the injected thermal power phi at the heat source by all known output forcesk(k∈Vs-f) And the temperature distribution of the return water of the whole network obtained in the step S25
Figure BDA00027503096300001211
Calculating the water supply temperature update values of all the output fixed heat sources through the formula (7)
Figure BDA00027503096300001212
Figure BDA00027503096300001213
S27, comparing the maximum value of the water supply temperature deviation at all the output fixed heat sources before and after updating
Figure BDA00027503096300001214
And the allowed convergence error err, where k ∈ Vs-f：
If it is
Figure BDA0002750309630000131
Then according to
Figure BDA0002750309630000132
Correcting the water supply temperature of all the output fixed heat sources, and returning to the step S23 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S28 is switched to;
s28, ending the iterative process, and outputting all the quantities to be solved of the first-stage energy flow calculation model:
Figure BDA0002750309630000133
φk(k∈Vs-a) And Tk(k ∈ E), wherein:
Figure BDA0002750309630000134
and S3, calculating output updated values of all output adjustable heat source units based on the initial dynamic energy flow result obtained in the step S2 and the minimum adjustable interval of the heat source units, and taking the output updated values as input quantities of the second-stage energy flow calculation model. The output update values of all the output adjustable heat source units are as follows:
Figure BDA0002750309630000135
in the formula:
Figure BDA0002750309630000136
representing the output updated value of the kth output adjustable heat source unit in the ith adjusting period;
Figure BDA0002750309630000137
the duration of each adjustment period is represented and must be smaller than the minimum adjustable interval of the unit; t is t0Representing an initial point in time of the fluence calculation; phi is akiRepresenting the output value of the kth output-adjustable heat source unit in the ith adjusting period obtained by the first-stage energy flow calculation;
Figure BDA0002750309630000138
a set of indices representing all adjustment periods.
S4, based on the output update values of all the output adjustable heat source units obtained in the step S3, obtaining the final result of the network dynamic energy flow through a second-stage iterative algorithm, wherein the method specifically comprises the following steps:
s41, inputting all known quantities of the second stage power flow calculation model: phi is ak(k∈Vs)、φk(k∈Vl)、qk(k∈E)、
Figure BDA0002750309630000139
G (V, E) and Θ (E);
s42, setting the output values of all the heat source units with adjustable output as
Figure BDA00027503096300001310
The water supply temperatures of all heat sources in the first-stage energy flow calculation result are used as initial values of the water supply temperatures of the heat sources in the second-stage energy flow calculation
Figure BDA00027503096300001311
S43, the flow rate q of hot water in each water supply pipeline is knownk(k∈Es) Initial value of water supply temperature of heat supply network
Figure BDA0002750309630000141
And the initial value of the water supply temperature of all heat sources
Figure BDA0002750309630000142
Calculating the temperature distribution of the whole network water supply through the formula (4)
Figure BDA0002750309630000143
S44, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S43
Figure BDA0002750309630000144
Calculating the return water temperature at all the loads by the formula (5)
Figure BDA0002750309630000145
S45, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure BDA0002750309630000146
And the return water temperatures at all the loads determined in step S44
Figure BDA0002750309630000147
Calculating the temperature distribution of the return water of the whole network by the formula (6)
Figure BDA0002750309630000148
S46, injecting heat power phi from all known heat sourcesk(k∈Vs) And the temperature distribution of the return water of the whole network obtained in the step S45
Figure BDA0002750309630000149
Calculating the supply water temperature update values at all heat sources by equation (7)
Figure BDA00027503096300001410
S47, comparing the maximum value of the water supply temperature deviation at all heat sources before and after updating
Figure BDA00027503096300001411
And the allowed convergence error err, where k ∈ Vs：
If it is
Figure BDA00027503096300001412
Then according to
Figure BDA00027503096300001413
Correcting the water supply temperature of all heat sources, and returning to the step S43 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S48 is switched to;
s48, ending the iterative process, and outputting all the quantities to be solved of the second-stage energy flow calculation model:
Figure BDA00027503096300001414
therefore, the final dynamic energy flow result of the quality-adjusting hot water pipe network can be obtained.
The simulation total time of this embodiment is 5 hours, the time step is 60 seconds, the space step is 40 meters, the heat source #2 is adjusted every 10 minutes, and the simulation results are shown in fig. 3 to 7. FIG. 3 is a graph of the variation of heat power taken at a load, which belongs to the input quantity of the energy flow calculation model. FIG. 4 is a graph of injected thermal power variation at a heat source, where heat sources #1 and #3 are fixed output heat sources and belong to the input quantities of the energy flow calculation model; heat source #2 is an output-adjustable heat source, the result of which is the output of the power flow calculation model, which assumes the task of eliminating unbalanced thermal power on the supply and demand sides, and thus the trend of change is opposite to the net fluctuation of thermal power of the system.
Fig. 5 shows the supply water temperature variation at 3 heat sources. The output of the heat sources #1 and #3 is fixed, so that the variation amplitude of the water supply temperature is large; the output of the heat source #2 is adjustable, the control target of the first stage is to maintain the water supply temperature to be fixed, and the water supply temperature is slightly changed due to the limitation of adjustable intervals of the unit in the second stage.
Figure 6 shows the water temperature change at the water supply network nodes 10, 18 and 26. The temperature of the water supply at the node 10 is mainly comprehensively influenced by the heat source #1 and the heat source #2, and the temperature of the water supply at the heat source #2 is not changed greatly, so that the temperature of the water supply mainly changes along with the heat source #1 and has a larger time delay; the water supply temperature at the node 18 mainly follows the water supply temperature change at the heat source #3, and has a delay; the supply water temperature at node 26 mainly follows the supply water temperature at heat source #2 and therefore fluctuates less. Fig. 7 shows the water temperature change conditions at the water return network nodes 5, 25 and 34, and the change conditions are approximately inversely related to the change trend of the heat source injection heat power by considering the hot water transmission delay. The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited by the foregoing examples, which are provided to illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is also intended to be covered by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (7)

1. The invention discloses a dynamic energy flow calculation method of a two-stage quality regulation hot water heating network, which is characterized by comprising the following steps of:
s1, establishing a dynamic energy flow calculation model of the hot water heating network in a quality regulation operation mode, dividing an energy flow calculation process into two stages, and determining the known quantity and the quantity to be obtained of each stage model;
s2, setting initial values of water supply temperature at all output fixed heat sources, and obtaining an initial result of the dynamic energy flow of the hot water heat supply network through a first-stage iterative algorithm;
s3, calculating output updated values of all output adjustable heat source units based on the initial result of the dynamic energy flow in the step S2 and the minimum adjustable interval of the heat source units, and taking the output updated values as input flow of the second-stage energy flow calculation model;
and S4, based on the output update values of all the output adjustable heat source units obtained in the step S3, obtaining the final result of the network dynamic energy flow through a second-stage iterative algorithm.
2. The method for calculating the dynamic energy flow of the two-stage quality-control hot water heating network according to claim 1, wherein the hot water heating network is in a quality-control operation mode in step S1, that is, the flow of each branch is kept constant, and the dynamic energy flow calculation model is as follows:
Figure FDA0002750309620000011
in the formula: t and TeRespectively representing the temperature of a heating medium in the pipeline and the temperature of the environment outside the pipeline; f. q and c respectively represent the flow rate, flow and specific heat capacity of the heating medium; r is the thermal resistance of the pipeline; t and x represent temporal and spatial variables, respectively; e represents the set of all branches in the heat network;
Figure FDA0002750309620000012
and
Figure FDA0002750309620000013
respectively representing the flow of heat medium flowing into the node n from the node k and the flow of heat medium flowing out of the node n to the node k; v represents the set of all nodes of the heat supply network;
Figure FDA0002750309620000014
and
Figure FDA0002750309620000015
all branch sets respectively representing the hot medium inflow and outflow nodes n;
Figure FDA0002750309620000016
the terminal temperature of the k-th pipeline with the heating medium flowing into the node n is shown; t isnRepresents the temperature of the heating medium at node n;
Figure FDA0002750309620000017
the head end temperature of the k-th pipeline with the heat medium flowing out of the node n is shown; phi is akRepresents the thermal power contained by node k or branch k;
Figure FDA0002750309620000021
and
Figure FDA0002750309620000022
respectively representing the supply water temperature and the return water temperature of the node k or the branch k.
3. The method of claim 2, wherein the power flow calculation process is divided into two stages in step S1, including a first stage power flow calculation model and a second stage power flow calculation model, the known flows of the first stage power flow calculation model including:
1) injected thermal power phi of all the output fixed heat sourcesk(k∈Vs-f)；
2) Water supply temperature at all output adjustable heat sources
Figure FDA0002750309620000023
3) Heat output power phi at all thermal loadsk(k∈Vl)；
4) Flow q of hot water in each pipek(k∈E)；
5) Initial value of supply and return water temperature of heat supply network
Figure FDA0002750309620000024
6) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline;
wherein: vs-1Representing a set of all heat source nodes with fixed output thermal power; vsRepresenting the set of all heat source nodes with adjustable output thermal power; vlRepresenting a set of all load nodes;
the first-stage energy flow calculation model comprises the following steps:
1) water supply temperature at all output fixed heat sources
Figure FDA0002750309620000025
2) Injected thermal power phi of all the power adjustable heat sourcesk(k∈Vs-a)；
3) Water temperature distribution in heat network at any time
Figure FDA0002750309620000026
4. The method of claim 3, wherein the known quantities of the second stage energy flow calculation model in step S1 include:
1) injected thermal power phi at all heat sourcesk(k∈Vs)；
2) Heat output power phi at all thermal loadsk(k∈Vl)；
3) Flow q of hot water in each pipek(k∈E)；
4) Initial value of supply and return water temperature of heat supply network
Figure FDA0002750309620000027
5) Topological parameters G (V, E) of the heat supply network and physical parameters theta (E) of the pipeline;
the second stage energy flow calculation model comprises the following steps: heating network at any timeInternal water temperature distribution
Figure FDA0002750309620000031
5. The method for calculating the dynamic power flow of the two-stage quality-control hot water heating network according to claim 3, wherein the step S2 of obtaining the preliminary result of the dynamic power flow of the hot water heating network through the first-stage iterative algorithm comprises the following steps:
s21, inputting all known quantities of the first-stage power flow calculation model based on the dynamic power flow calculation model;
s22, setting the initial values of the water supply temperature at all the positions of the output fixed heat sources
Figure FDA0002750309620000032
S23, adjusting the temperature of the water supply at the heat source by all known output forces
Figure FDA0002750309620000033
Flow q of hot water in each water supply pipek(k∈Es) Initial value of water supply temperature of heat supply network
Figure FDA0002750309620000034
And the initial values of the water supply temperatures of all the output fixed heat sources
Figure FDA0002750309620000035
Calculating the whole network water supply temperature distribution
Figure FDA0002750309620000036
Wherein EsRepresenting the collection of all pipes in the water supply network;
s24, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S23
Figure FDA0002750309620000037
Calculating the return water temperature at all loads
Figure FDA0002750309620000038
S25, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure FDA0002750309620000039
And the return water temperatures at all the loads determined in step S24
Figure FDA00027503096200000310
Calculating the whole-network backwater temperature distribution
Figure FDA00027503096200000311
Wherein ErRepresenting the set of all pipelines in the water return pipe network;
s26, fixing the injected thermal power phi at the heat source by all known output forcesk(k∈Vs-f) And the temperature distribution of the return water of the whole network obtained in the step S25
Figure FDA00027503096200000312
Calculating the water supply temperature update values of all the output fixed heat sources
Figure FDA00027503096200000313
S27, comparing the maximum value of the water supply temperature deviation at all the output fixed heat sources before and after updating
Figure FDA00027503096200000314
And a predetermined allowable convergence error err, where k ∈ Vs-f：
If it is
Figure FDA00027503096200000315
Then according to
Figure FDA00027503096200000316
Correcting the water supply temperature of all the output fixed heat sources, and returning to the step S23 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S28 is switched to;
s28, ending the iterative process, and outputting all the quantities to be solved of the first-stage energy flow calculation model:
Figure FDA0002750309620000041
φk(k∈Vs-a) And
Figure FDA0002750309620000042
wherein
Figure FDA0002750309620000043
6. The method for calculating the dynamic power flow of a two-stage quality-control hot water heating network according to claim 1, wherein in step S3, the method for calculating the output updated values of all the output-adjustable heat source units comprises:
Figure FDA0002750309620000044
in the formula:
Figure FDA0002750309620000045
representing the output updated value of the kth output adjustable heat source unit in the ith adjusting period;
Figure FDA0002750309620000046
the duration of each adjustment period is represented and must be smaller than the minimum adjustable interval of the unit; t is t0Representing an initial point in time of the fluence calculation; phi is akiIndicating that the kth output-adjustable heat source unit obtained by the first-stage energy flow calculation is adjusted at the ithThe output value in a time-saving period;
Figure FDA0002750309620000047
a set of indices representing all adjustment periods.
7. The method for calculating the dynamic power flow of the two-stage quality-control hot water heating network according to claim 4, wherein in the step S4, the method for obtaining the final result of the dynamic power flow of the network through the second-stage iterative algorithm comprises the following steps:
s41, inputting all known quantities of the second-stage power flow calculation model based on the dynamic power flow calculation model;
s42, setting the output values of all the heat source units with adjustable output as
Figure FDA0002750309620000048
The water supply temperatures of all heat sources in the first-stage energy flow calculation result are used as initial values of the water supply temperatures of the heat sources in the second-stage energy flow calculation
Figure FDA0002750309620000049
S43, the flow rate q of hot water in each water supply pipeline is knownk(k∈Es) Initial value of water supply temperature of heat supply network
Figure FDA00027503096200000410
And the initial value of the water supply temperature of all heat sources
Figure FDA00027503096200000411
Calculating the whole network water supply temperature distribution
Figure FDA00027503096200000412
S44, obtaining heat power phi from all known heat loadsk(k∈Vl) And the temperature distribution of the whole network supplied water determined in step S43
Figure FDA00027503096200000413
Calculating the return water temperature at all loads
Figure FDA00027503096200000414
S45, according to the known hot water flow q in each water return pipelinek(k∈Er) Initial value of return water temperature of heat supply network
Figure FDA0002750309620000051
And the return water temperatures at all the loads determined in step S44
Figure FDA0002750309620000052
Calculating the whole-network backwater temperature distribution
Figure FDA0002750309620000053
S46, injecting heat power phi from all known heat sourcesk(k∈Vs) And the temperature distribution of the return water of the whole network obtained in the step S45
Figure FDA0002750309620000054
Calculating water supply temperature update values at all heat sources
Figure FDA0002750309620000055
S47, comparing the maximum value of the water supply temperature deviation at all heat sources before and after updating
Figure FDA0002750309620000056
And the allowed convergence error err, where k ∈ Vs：
If it is
Figure FDA0002750309620000057
Then according to
Figure FDA0002750309620000058
Correcting the water supply temperature of all heat sources, and returning to the step S43 after correction;
otherwise, the power flow calculation result meets the precision requirement, and the step S48 is switched to;
s48, ending the iterative process, and outputting all the waiting-to-demand quantities of the second-stage energy flow calculation model
Figure FDA0002750309620000059
Therefore, the final dynamic energy flow result of the quality-adjusting hot water pipe network can be obtained.
CN202011181460.0A 2020-10-29 2020-10-29 Dynamic energy flow calculation method for two-stage quality regulation hot water heating network Pending CN112257281A (en)

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