CN106777708B - Steady state analysis method of electric power-natural gas regional comprehensive energy system - Google Patents

Steady state analysis method of electric power-natural gas regional comprehensive energy system Download PDF

Info

Publication number
CN106777708B
CN106777708B CN201611192565.XA CN201611192565A CN106777708B CN 106777708 B CN106777708 B CN 106777708B CN 201611192565 A CN201611192565 A CN 201611192565A CN 106777708 B CN106777708 B CN 106777708B
Authority
CN
China
Prior art keywords
natural gas
energy
power
pressure
node
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201611192565.XA
Other languages
Chinese (zh)
Other versions
CN106777708A (en
Inventor
王丹
王伟亮
贾宏杰
陈沼宇
余晓丹
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tianjin University
Original Assignee
Tianjin University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tianjin University filed Critical Tianjin University
Priority to CN201611192565.XA priority Critical patent/CN106777708B/en
Publication of CN106777708A publication Critical patent/CN106777708A/en
Application granted granted Critical
Publication of CN106777708B publication Critical patent/CN106777708B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
    • Y02P90/80—Management or planning
    • Y02P90/82—Energy audits or management systems therefor

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)

Abstract

The invention discloses a steady state analysis method for a power-natural gas regional comprehensive energy system, which comprises the following steps of (1) modeling and solving a natural gas system in the power-natural gas regional comprehensive energy system; step (2), analyzing the node pressure-load sensitivity of the natural gas system; constructing energy coupling link modeling and energy conversion analysis with an energy hub as a core based on natural gas system information and energy interaction information; step (4), solving the steady state of the power system; and (5) constructing a steady-state analysis comprehensive solving model of the comprehensive energy system in the electric power-natural gas area, and obtaining the influence caused by the change of the network state of the natural gas system. Aiming at the operation scene of 'gas-fixed-power', the invention explores the influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system, and provides a certain theoretical basis for the analysis of energy mutual aid and mutual influence under the background of the energy Internet.

Description

Steady state analysis method of electric power-natural gas regional comprehensive energy system
Technical Field
The invention relates to the fields of energy internet, comprehensive energy systems, natural gas systems and smart power grids, in particular to a steady-state analysis method for a comprehensive energy system in an electric power-natural gas region.
Background
Energy is the basis of national development, and in recent years, with the continuous popularization of concepts such as energy internet, comprehensive energy system and the like, the development of the energy system shows diversified, intelligent and informatization trends. In a regional comprehensive energy system formed by electric power, natural gas and a thermodynamic system, the energy coupling is tight, the complementation and the complementation are realized, and the cascade utilization and the cooperative optimization of the energy can be realized. The supply and demand characteristics of different forms of energy are combined, the synergistic effect and the mutual influence of the energy are fully considered, and the key for improving the energy utilization efficiency in the comprehensive energy system is realized; on the other hand, different energy systems can support each other through energy coupling, improve energy supply system stability. The natural gas system has the characteristics of easiness in storage, greenness, cleanness, safety, reliability and the like; meanwhile, with the wide application of technologies such as gas turbines, Combined Heat and Power (CHP) and the like and the continuous research on Energy Hub (EH) technology, the importance of natural gas in Energy systems is more and more significant. The coupling between energy systems is continuously strengthened, and the interaction and the cooperative optimization method need to be studied deeply.
Natural Gas Systems (NGS) have certain similarity with power systems, and are particularly obvious in aspects such as steady-state modeling and tidal current analysis characteristics, so that research can be carried out by taking the existing analysis ideas of the power systems as reference. The main differences between natural gas systems and electrical power systems are: the former has large-scale storage characteristics and special requirements on gas quality, and analysis of the difference is often the key to improve the energy supply quality of the comprehensive energy system. The natural gas is composed of a plurality of gas components, and the gas quality of the natural gas changes after other natural gas types are introduced into the system or a new gas injection point appears. The network state of the natural gas system is influenced by factors such as gas quality, structure and pressure, and when the factors are changed, the traditional natural gas system analysis method is difficult to apply. The invention mainly discusses the influence of two factors of 'natural gas quality change' and 'gas injection point introduction' on the natural gas system and other parts of the regional comprehensive energy system with the coupling relation, and how to construct an applicable natural gas system analysis model and a comprehensive steady-state solving framework is the key of the natural gas system analysis model and the comprehensive steady-state solving framework.
The prior art has at least the following disadvantages and shortcomings: at present, the discussion of the integrated energy system by researchers in the related art is mainly focused on the trans-regional level, and in addition, the related research neglects the natural gas network state characteristics and assumes them to be stable and unchangeable. The limitations of these methods are that the research has relatively few discussions on the regional comprehensive energy system that mainly includes a Power distribution system (having a three-phase unbalanced flow characteristic) and a Gas distribution system (having a low-voltage natural Gas network characteristic) and is closely coupled with energy, and meanwhile, due to the application of the Power to Gas (P2G) technology, the network state of the natural Gas system may change (for example, the Gas quality of the natural Gas changes and a new Gas injection point is introduced), and the conventional analysis method is not suitable any more, and has certain limitations.
Disclosure of Invention
In order to solve the problems, the invention provides a steady-state analysis method of an electric power-natural gas regional comprehensive energy system.
The invention provides a steady state analysis method of a power-natural gas regional comprehensive energy system, which comprises the following steps:
the method comprises the following steps of (1) modeling and solving a natural gas system in an electric power-natural gas area comprehensive energy system; the method specifically comprises the following steps:
reading natural gas network information, distributed generation unit information and energy interaction information;
analyzing natural gas network characteristics and constructing a node admittance matrix;
for a pressure-known node in a natural gas system, the natural gas flow equations for different pressure levels are as follows:
Figure BDA0001187502800000031
(a) formula (a) applies to a pressure range of 0-75mbar, (b) formula (b) applies to a pressure range of 0.75-7.0bar, and (c) formula applies to a pressure range of greater than 7.0 bar;
wherein i and j are respectively the head and tail nodes of the natural gas pipeline, and qijIs the pipe flow under standard conditions, piAnd pjRespectively, the gauge node pressure, D and L are the diameter and the length of the pipeline, SG is the relative density, f is the friction coefficient, Z is a calculation constant, TnAnd pnTemperature and pressure under standard conditions;
step (2), analyzing the node pressure-load sensitivity of the natural gas system, and enabling the natural gas node pressure-load sensitivity matrix
Figure BDA0001187502800000032
Wherein p is pressure and l is load;
and (3) constructing energy coupling link modeling and energy conversion analysis with an energy hub as a core based on natural gas system information and energy interaction information, and specifically comprising the following steps of:
reading external environment parameters and distributed capacity unit information;
analyzing the equipment type, energy interaction information and structural characteristics of the energy concentrator according to the current state;
constructing an energy hub conversion matrix C and an equation L which is CP, and analyzing the interaction mode of the coupling equipment;
solving for xeAnd xgChanging the value: carrying out numerical value conversion on energy interaction of the coupling equipment;
integrating energy interaction information and solving an energy concentrator equation;
step (4), solving the steady state of the power system, and calculating the power loss of each part of the line section by the load power step by taking the initial end voltage and the tail end load of the power distribution network as known conditions in the process of back generation so as to calculate the initial end power; in the forward process, the voltage at the starting end and the power at the starting end obtained in the above process are used as known conditions, the voltage drop is used as a required quantity, the calculation is carried out from the starting end to the tail end of the line, and the voltage of each node is further obtained. Repeating the forward and backward substitution processes, stopping when the convergence condition is met, and outputting a result; if the calculation results of the power system are in the reasonable operation interval of the system, finishing the calculation and outputting the result; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration;
step (5), combining comprehensive solving information of a natural gas system and an electric power system, constructing a steady state analysis comprehensive solving model of the electric power-natural gas regional comprehensive energy system, and firstly reading in external environment information; outputting variables to be solved of the natural gas system and a pressure-load sensitivity matrix of the natural gas system according to the initialization part and the solving part of the natural gas system; analyzing an energy coupling link taking an energy concentrator as a core, and performing numerical value conversion on energy interaction of coupling equipment; finally, substituting the information into the calculation process of the power system, and if the calculation results of the power system are all in the reasonable operation interval of the system, finishing the calculation and outputting the result; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration; therefore, the influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system is obtained.
1. The steady-state analysis method for the power-natural gas regional integrated energy system according to claim 1, wherein the process of solving the natural gas system in the power-natural gas regional integrated energy system comprises the following steps "
Initialization: determining relevant parameters required by solving a natural gas system according to the natural gas network state;
by using the thought of graph theory, an incidence matrix A of nodes and branches for showing network topology information is constructed, and an element A of the incidence matrix AijAs defined below:
Figure BDA0001187502800000041
a natural gas system is described, with the formula:
Figure BDA0001187502800000042
Figure BDA0001187502800000043
wherein the content of the first and second substances,
Figure BDA0001187502800000044
in order to know the pressure at the node point,
Figure BDA0001187502800000045
in order for the pressure at the node to be unknown,
Figure BDA0001187502800000046
representing a pipeline flow equation determined according to a natural gas flow formula;
Figure BDA0001187502800000051
in order to be the net load capacity,
Figure BDA0001187502800000052
and
Figure BDA0001187502800000053
and respectively the natural gas injection amount and the natural gas consumption amount of a certain node. The above equation characterizes the meaning that the amount of natural gas flowing into a node is equal to the amount flowing out of the node plus the net load at the node; at the moment, the natural gas flow problem is further expressed as that the flow of a node with known pressure and the pressure of the node with known flow are obtained according to the known information;
solving the load flow by using a Newton method in power system load flow analysis for reference, and expressing an error equation F as follows:
Figure BDA0001187502800000054
the jacobian matrix J for constructing a natural gas system is as follows:
Figure BDA0001187502800000055
wherein p isiAnd pjRepresenting node pressure, qijThe pipeline flow under the standard condition; a. the1To eliminate reduced correlation matrices outside the pressure-known nodes, A1 TIs A1The transposed matrix of (2);
Figure BDA0001187502800000056
as unknown nodesThe pressure of (a).
And repeatedly iterating the pressure value of the natural gas system by constructing the Jacobian matrix and applying a Newton-Raphson method until the value of the error equation is smaller than the convergence standard, and outputting a trend result.
The discrete solving method applied by the invention is used for integrally analyzing the power-natural gas regional comprehensive energy system, exploring the influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system aiming at the operation scene of 'fixing power by gas', and providing a certain theoretical basis for the analysis of energy mutual aid and mutual influence under the energy internet background.
Drawings
FIG. 1 is a steady state solving flow chart of the power-natural gas regional comprehensive energy system provided by the invention;
fig. 2 is a schematic diagram of three typical energy hub structures, with reference numbers: (1) type I energy concentrator, (2), type II energy concentrator, (3) and type III energy concentrator;
FIG. 3 is a schematic diagram of an electric power-natural gas regional integrated energy system;
FIG. 4 is a schematic illustration of a natural gas pressure-load sensitivity matrix;
fig. 5 is a graph illustrating the variation result of the voltage amplitudes of the phases of the power system under the condition that different gases are injected into the natural gas system.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, the steady state solving idea of the power-natural gas regional comprehensive energy system is mainly divided into four parts, firstly, the network state change of the natural gas system is analyzed, whether a gas injection point or gas quality changes is judged, a natural gas system solving model is adjusted according to the change, and the initialization setting of the natural gas system is completed, wherein the parameters specifically comprise the relative density of natural gas, a node-branch correlation matrix, a friction coefficient and the like; secondly, solving a power flow equation of the natural gas system by a Newton method, and solving a natural gas sensitivity matrix according to the result; thirdly, analyzing an energy coupling ring energy-saving interaction mode and carrying out numerical solution by combining the related information of the natural gas system; finally, substituting the information into the calculation process of the power system, solving the steady state of the power system, and finishing the calculation and outputting the result if the calculation results of the power system are all in the reasonable operation interval of the system; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration; and (3) combining the comprehensive solving information, constructing a steady-state analysis comprehensive solving model of the comprehensive energy system in the electric power-natural gas region, and exploring the influence of the change of the network state of the natural gas system on the natural gas system and the electric power system coupled with the natural gas system.
Step 1, modeling and solving a natural gas system in an electric power-natural gas regional comprehensive energy system
Step 2, analyzing the node pressure-load sensitivity of the natural gas system;
step 3, constructing energy coupling link modeling and energy conversion analysis with an energy hub as a core based on natural gas system information and energy interaction information;
step 4, solving the steady state of the power system; in the steady-state solution of the power system, a forward-backward generation method is mainly applied. Specifically, in the process of back generation, the initial end voltage and the end load of the power distribution network are used as known conditions, the power loss of each part of the line is gradually calculated section by section according to the load power, and then the initial end power is calculated; in the forward process, the voltage at the starting end and the power at the starting end obtained in the above process are used as known conditions, the voltage drop is used as a required quantity, the calculation is carried out from the starting end to the tail end of the line, and the voltage of each node is further obtained. And repeating iteration of the forward and backward substitution processes, stopping when the convergence condition is met, and outputting a result.
And 5, constructing a steady state analysis comprehensive solving model of the electric power-natural gas regional comprehensive energy system, and exploring the influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system on the basis. The influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system is obtained. In this step, the external environment information (for example, the output situation of the distributed power generation unit) is read in firstly; outputting variables to be solved (such as pipeline flow and node pressure) of the natural gas system and a pressure-load sensitivity matrix of the natural gas system according to the initialization part and the solving part of the natural gas system; analyzing an energy coupling link taking an energy concentrator as a core, and performing numerical value conversion on energy interaction of coupling equipment; finally, the information is brought into the calculation process of the power system, and if the calculation results of the power system are all in the reasonable operation interval of the system, the calculation is finished and the result is output; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration.
The step (1) is specifically as follows:
the natural gas system mainly comprises two nodes, wherein one node is a node with known pressure, is generally a gas source point, has fixed and known pressure, and has flow passing through the point as a required quantity, which is similar to a balance node in a power system; the other is a node with known flow, typically a load node, whose pressure is a backlog, similar to the PQ node in the power system (node where active power P and reactive power Q are given, node voltage and phase are backlog). In the step, a relatively mature steady-state analysis thought of the power system is used for reference, modeling and solving are carried out on the natural gas system, and network state change of the natural gas system (such as natural gas quality change and introduction of a new gas injection point) is considered. From the perspective of natural gas system modeling, changes in the gas quality of natural gas primarily affect its relative density; the introduction of gas injection points often requires the laying of corresponding pipelines to connect to the natural gas system, which means that the node-branch correlation matrix of the natural gas system changes over its area, and also causes changes in relative density.
The branches of the natural gas system can be divided into compressor-free branches and compressor-containing branches. The pressure drop exists at the two ends of the natural gas pipeline, the flow of the pipeline is the quantity to be solved, the quantity is related to the pressure at the two ends of the pipeline, and the formula is related to the pressure grade of the pipeline and the corresponding network parameters. The natural gas system meets the conservation law of fluid mechanics mass and the Bernoulli equation in operation, and the natural gas flow formulas of different pressure levels based on certain assumptions are as follows:
Figure BDA0001187502800000081
wherein (a) applies to a pressure range of 0-75mbar, (b) applies to a pressure range of 0.75-7.0bar, and (c) applies to a pressure range of greater than 7.0 bar. i and j are the natural gas pipeline head and end nodes respectively, qijIs the pipe flow under Standard conditions (STP), piAnd pjRepresenting the nodal pressure, D and L are the diameter and length of the pipe, SG is the relative density, f is the coefficient of friction, Z is a calculation constant, TnAnd pnThe temperature and pressure under standard conditions. In the regional integrated energy system, because the natural gas pressure level is not high, a low-pressure scene calculation formula given by the formula (a) or (b) is often needed.
In the trend solution of the natural gas system, firstly, the network topology information is shown by constructing an incidence matrix A of nodes and branches by using the thought of graph theory, and an element A of the incidence matrix AijAs defined below:
Figure BDA0001187502800000082
A1in order to eliminate the reduced incidence matrix except the nodes with known pressure, the method is clear, simple and convenient and is convenient for programming and calling.
Determining the natural gas flow formula according to the pressure grade of the natural gas system; the natural gas system may be described by the following equation:
Figure BDA0001187502800000083
Figure BDA0001187502800000084
wherein the content of the first and second substances,
Figure BDA0001187502800000085
in order to know the pressure at the node point,
Figure BDA0001187502800000086
in order for the pressure at the node to be unknown,
Figure BDA0001187502800000087
representing a pipeline flow equation determined according to a natural gas flow formula;
Figure BDA0001187502800000088
in order to be the net load capacity,
Figure BDA0001187502800000089
and
Figure BDA00011875028000000810
and respectively the natural gas injection amount and the natural gas consumption amount of a certain node. The above equation characterizes the meaning that the amount of natural gas flowing into a node is equal to the amount flowing out of the node plus the net load at the node. In this case, the natural gas flow problem can be further expressed as finding the flow rate of the node with known pressure and the pressure of the node with known flow rate according to the known information.
The above equation is a typical nonlinear equation, for a given pressure initial value, the left side and the right side of the pressure initial value are often not equal, at this time, the pressure initial value can be solved by taking the newton method in power flow analysis of the power system as a reference, and an error equation F is as follows:
Figure BDA0001187502800000091
the key point of applying the Newton method is to derive a Jacobian matrix of the Newton method, the Jacobian matrix of the natural gas solving equation can be uniformly written into the form of the formula after derivation, the pressure value of the natural gas system is repeatedly iterated by constructing the Jacobian matrix and applying the Newton-Raphson method until the value of the error equation is smaller than the convergence standard, and a load flow result is output. The jacobian matrix J is shown below:
Figure BDA0001187502800000092
Figure BDA0001187502800000093
Figure BDA0001187502800000094
wherein p isiAnd pjRepresenting node pressure, qijIs the pipeline flow under standard conditions.
The method for solving the natural gas network trend by using the Newton method has the characteristics of clear structure, strong applicability and the like, and the method needs to have certain knowledge on a system to be solved and give a reasonable initial value. Through verification of various examples, the solution model is efficient and stable.
For the branch containing the compressor, the following equation is used for analysis:
Figure BDA0001187502800000095
Rkij＝pj/pi
Figure BDA0001187502800000096
wherein HkijRepresenting the power required by the compressor, BkIs a parameter related to the temperature, efficiency, adiabatic index of the compressor, fkIs the flow through the compressor conduit; rkijIs the compression ratio. The compressor operation needs extra power, when the part of power is provided by natural gas through the gas turbine, the consumed natural gas flow is tau, alpha, beta and gamma in the equation, and the fuel ratio coefficient of the gas turbine is gamma; the power required for the compressor operation may also be provided by the grid.
The method adopts a node method to divide the power flow equation of a natural gas system, and solves the equation through a Newton method, and for the natural gas system with n nodes, when the Newton method is used for carrying out the kth iterative solution, the correction equation is as follows:
Figure BDA0001187502800000101
Figure BDA0001187502800000102
wherein the content of the first and second substances,
Figure BDA0001187502800000103
Figure BDA0001187502800000104
is the error vector of the function being evaluated,
Figure BDA0001187502800000105
to an error equation, J(k)For the purpose of this jacobian matrix,
Figure BDA0001187502800000106
is the correction amount vector at this time, fNG1…fNGnRepresenting the natural gas equation associated with node n for node 1 …. By repeatedly iterating the above formula, the calculated variables gradually approach the real solution of the system until the convergence condition is satisfied, and the result is output. By optimizing the initial values, the final result can be obtained with a smaller number of iterations.
The step (2) is specifically as follows:
let the natural gas system equation be represented by f (p, l) ═ 0, where p represents pressure and l represents load. Let the steady state operating point of the natural gas system be (p)0,l0) The operating point of the system will become (p) after the disturbance0+Δp,l0+ Δ l). To determine the relationship between p and the amount of change l, in (p)0,l0) And f (p, l) is expanded to 0 according to Taylor series, and a term is taken once to obtain:
Figure BDA0001187502800000107
wherein, due to f (p)0,l0) When the value is 0, the following components are:
Figure BDA0001187502800000108
namely:
Figure BDA0001187502800000109
let the natural gas node pressure-load sensitivity matrix
Figure BDA00011875028000001010
And since the load l is quantitative and generally known,
Figure BDA00011875028000001011
then
Figure BDA00011875028000001012
Namely, the natural gas pressure-load sensitivity matrix is equal to the negative of the inverse of the Jacobian matrix solved by the natural gas system power flow. The pressure-load sensitivity related information can provide help for the position of the gas injection point of the natural gas system on one hand; on the other hand, auxiliary information can be provided for adjustment of the energy coupling link in the steady-state comprehensive solution. The node pressure-load sensitivity analysis of the natural gas system can provide a certain theoretical basis for load adjustment.
The step (3) specifically comprises the following steps: describing the coupling relation of energy conversion, distribution, utilization and the like in the regional comprehensive energy system through an energy hub model, and cooperatively considering energy sources such as electric power, natural gas, heat and the like; constructing a typical energy hub model containing elements such as an air conditioning system, a micro gas turbine, a gas boiler and the like; when the running state of the comprehensive energy system is analyzed to change, the numerical value conversion is carried out on the energy-saving interaction of the energy coupling loop
In order to analyze and solve the power-natural gas regional comprehensive energy system and simultaneously discuss the influence of the change of the natural gas system on the natural gas system and the energy system coupled with the natural gas system, the invention carries out detailed description on the technical scheme in detail through the following embodiments:
referring to fig. 2, three typical energy concentrators, i.e., type i, ii, iii energy concentrators, are used in the present invention, wherein:
the main components of the type i energy concentrator include a Transformer (T), an Air Conditioner (AC), and a Gas boiler (GF); l ise1And Lh1Representing power demand and thermal demand, Lh1Either supplied by GF or converted by AC; pe1And Pg1Respectively representing power input and natural gas input, lambda1Representing the distribution coefficient, i.e. λ1Pe1Represents the power distributed to the AC by the power input; etaT、ηACAnd ηGFEnergy conversion efficiencies of T, AC and GF links are shown, respectively. Thus, the energy hub can be written as follows:
Figure BDA0001187502800000111
the main elements of the type II energy concentrator comprise a Heat Exchanger (HE), a Compressor (C) and an electric Heater (Heater, H), an electric power system carries out electric Heat conversion through the H and provides energy for a natural gas system through the C, and the required power of the part is related to the compression ratio of the Compressor; l ise2And Lh2Representing power and heat demand, Lh2Either supplied by C or converted by H; pe2And Pg2Respectively representing power input and natural gas input, lambda2Representing the distribution coefficient, i.e. λ2Pe2Represents the power allocated to C by the power input; etaHE、ηCAnd ηHRespectively represents the energy conversion efficiency of HE, C and H links. The energy hub can be written as follows:
Figure BDA0001187502800000121
in the type iii energy hub, main components are a Micro gas Turbine (MT) and a Heat Exchanger (HE). The natural gas system supplies energy to the power system through the MT and plays a supporting role in the voltage level of the power system; at the same time, MT is also a variable load of the natural gas system, whose output level is considered herein to be influenced by the natural gas system. L ise3And Lh3Representing power demand and thermal demand, Lh3Supplied or converted by the MT; pe3And Pg2Respectively representing power input and natural gas input, lambda3Representing the distribution coefficient, i.e. λ3Pe3Represents the power allocated to the MT by the power input;
Figure BDA0001187502800000122
and
Figure BDA0001187502800000123
respectively showing the efficiency of the gas-to-electricity and gas-to-heat links of the MT. The energy hub model may be expressed as:
Figure BDA0001187502800000124
in the regional integrated energy system shown in fig. 3, the natural gas system is a modified low-pressure distribution network. Wherein, node 1 is the gas source point, and node 12 is the gas injection point. The network not only embodies the centralized gas supply characteristic (nodes 1-8) of the gas distribution network, but also embodies the radiation characteristic (nodes 9-11), and special users 1-3 are respectively connected with the nodes 9-11 through an electrically driven compressor 301. The special user has the natural gas pressure requirement of 38mbar pressure, so the compressors are respectively added in the corresponding branches, but the variable ratio of the compressors is limited, the value is 1.2-1.8, the system is easy to break down when the maximum variable ratio of the compressors is exceeded, and the user pressure cannot be met. The power system selects an IEEE34 node three-phase unbalanced system. The energy coupling link selects the I-III type energy concentrator. The complexity of this system coupling is embodied in:
1) the natural gas system has influence on the natural gas system due to the fact that the natural gas system contains different gas quality gases or gas injection points are added.
2) The natural gas with different gas qualities has different heat values, and under different conditions, the relation between the natural gas power required by the energy concentrator and the corresponding flow rate is changed.
3) The MT in the III type energy concentrator can support the voltage of the power system, but the pressure of the natural gas system is reduced along with the increase of the output of the III type energy concentrator, the transformation ratio of an electrically driven compressor is increased to meet the pressure requirement of a special user, the power output of the II type energy concentrator is increased along with the increase of the output of the II type energy concentrator, and the part of power is provided by the power system.
The natural gas pressure-load sensitivity is analyzed by using a node pressure-load sensitivity matrix S shown in figure 4 and a matrix element Sx,y(x, y is 2, 3.. 11) represents the effect of the load change of the node x on the pressure of the node y (the source point is the node 1), and the underlined part in each line represents the maximum value of the line, namely, the node with the largest pressure effect generated by the load change of the node x. According to the sensitivity matrix, the larger element of the matrix value appears in the lower right corner box, the maximum value of the matrix value corresponds to the node 11, because the nodes 9-11 are positioned at the tail end of the line and are supplied by a single pipeline, the load variation has the largest influence on the system pressure and accords with the actual condition of the network; the pressure-load sensitivity related information can provide help for the position of the gas injection point of the natural gas system on one hand; on the other hand, auxiliary information can be provided for adjustment of the energy coupling link in the steady-state comprehensive solution.
The gas injection points are introduced into the natural gas system, the distributed gas injection points are added near the original network nodes by combining the effective utilization of local renewable resources, and gases with different gas qualities, such as hydrogen, upgraded methane and the like are added. An increased gas injection point 12 near the node 3 was selected and the same flow (100 m) was added3H) hydrogen and upgraded biogas (from renewable energy utilization technologies such as P2G). For natural gas systems, an increase in gas injection points means a simultaneous change in network structure and natural gas quality; consider, respectively:
1) case 1: injecting hydrogen into the gas injection point;
2) case 2: injecting upgraded methane into the gas injection point;
under the condition that the network constraint is met, the change of the node voltage of the power system under the condition that the MT is under the maximum output at the moment is explored.
As shown in fig. 5, it can be seen from the results that the voltage supporting effect of the natural gas system on the power system is improved significantly after the distributed gas injection points are introduced under the condition that the overall energy requirements of the power system, the natural gas system and the energy hub are kept unchanged. The addition of distributed gas injection points has less effect on nodes 1-3 because the network state of the node is less changed because the node is closer to its gas source point. The gas injection point injects gases with different gas qualities to have different influences on the natural gas system, the relative density (value is 0.58) of the upgraded methane is closer to the relative density (value is 0.6048) of the original network, the total heat value is closer to the original network, and the natural gas system has better pressure lifting effect on the power system under the condition; in comparison, the relative density of the hydrogen injected at this point (value 0.0696) and the gross calorific value (value 12.75) differ more from the original network, although in this case the natural gas system pressure drop is smaller, a smaller gross calorific value means that more hydrogen needs to be burned to meet the same energy demand. In addition, the natural gas systems in different regions have great difference in hydrogen capacity, and the amount of hydrogen existing in the natural gas systems needs to be controlled within a certain range. However, generally, the introduction of the gas injection point improves the pressure drop level of the natural gas system, and increases the upper limit of the voltage supporting capacity of the natural gas system on the power system, which has a certain significance for improving the stability of the regional comprehensive energy system.
Those skilled in the art will appreciate that the drawings are only schematic illustrations of preferred embodiments, and the above-described embodiments of the present invention are merely provided for description and do not represent the merits of the embodiments.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Reference documents:
[1]Li Q,An S,Gedra T W.Solving natural gas loadflow problems using electric loadflow techniques[C]//Proceedings of the North American Power Symposium,Rolla，USA，2003:1-7.
[2]Geidl M,Andersson G.A modeling and optimization approach for multiple energy carrier power flow[C]//In Proceedings of IEEE PES Power Tech,St.Petersburg,Russian Federation.2005:1-7.
[3]Abeysekera M,Wu J,Jenkins N,et al.Steady state analysis of gas networks with distributed injection of alternative gas[J].Applied Energy,2015,164:991–1002.
[4]Andrzej J.Osiadacz.Simulation and Analysis of Gas Network[M].London:E.&F.N.Spon Ltd,1986.

Claims (2)

1. a steady state analysis method for an electric power-natural gas regional comprehensive energy system is characterized by comprising the following steps:
the method comprises the following steps of (1) modeling and solving a natural gas system in the electric power-natural gas area comprehensive energy system, and specifically comprises the following steps:
reading natural gas network information, distributed generation unit information and energy interaction information;
analyzing the natural gas network characteristics, judging whether a gas injection point or gas quality changes, adjusting a natural gas system solution model according to the change, and finishing the initialization setting of the natural gas system, wherein the initialization setting at least comprises the relative density of natural gas, a node-branch incidence matrix and friction coefficient parameters; secondly, solving a power flow equation of the natural gas system by a Newton method, and solving a natural gas sensitivity matrix according to the result; thirdly, analyzing an energy coupling ring energy-saving interaction mode and carrying out numerical solution by combining the related information of the natural gas system; finally, substituting the information into the calculation process of the power system, solving the steady state of the power system, and finishing the calculation and outputting the result if the calculation results of the power system are all in the reasonable operation interval of the system; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration; combining the comprehensive solving information to construct a steady-state analysis comprehensive solving model of the comprehensive energy system in the electric power-natural gas region;
adding distributed gas injection points near the original network nodes, and adding hydrogen and upgraded methane with the same flow; for natural gas systems, an increase in gas injection points means network structure and natural gas quality changes; under the condition of meeting network constraints, the change of the node voltage of the power system under the condition of maximum output of the MT at the moment is explored;
for a pressure-known node in a natural gas system, the natural gas flow equations for different pressure levels are as follows:
Figure FDA0002565844330000011
(a) formula (a) applies to a pressure range of 0-75mbar, (b) formula (b) applies to a pressure range of 0.75-7.0bar, and (c) formula applies to a pressure range of greater than 7.0 bar;
wherein i and j are respectively the head and tail nodes of the natural gas pipeline, and qijIs the pipe flow under standard conditions, piAnd pjRespectively, the gauge node pressure, D and L are the diameter and the length of the pipeline, SG is the relative density, f is the friction coefficient, Z is a calculation constant, TnAnd pnTemperature and pressure under standard conditions;
step (2), analyzing the node pressure-load sensitivity of the natural gas system, and enabling the natural gas node pressure-load sensitivity matrix
Figure FDA0002565844330000021
Wherein p is pressure and l is load;
and (3) constructing energy coupling link modeling and energy conversion analysis with an energy hub as a core based on natural gas system information and energy interaction information, and specifically comprising the following steps of:
reading external environment parameters and distributed capacity unit information;
analyzing the equipment type, energy interaction information and structural characteristics of the energy concentrator according to the current state;
constructing an energy hub conversion matrix C and an equation L which is CP, and analyzing the interaction mode of the coupling equipment;
solving for xeAnd xgChanging the value: carrying out numerical value conversion on energy interaction of the coupling equipment;
integrating energy interaction information and solving an energy concentrator equation;
step (4), solving the steady state of the power system, and calculating the power loss of each part of the line section by the load power step by taking the initial end voltage and the tail end load of the power distribution network as known conditions in the process of back generation so as to calculate the initial end power; in the process of forward pushing, the voltage of the initial end and the power of the initial end obtained in the process are used as known conditions, the voltage drop is used as a required quantity, calculation is carried out from the initial end to the tail end of the line, and then the voltage of each node is obtained; repeating the forward and backward substitution processes, stopping when the convergence condition is met, and outputting a result; if the calculation results of the power system are in the reasonable operation interval of the system, finishing the calculation and outputting the result; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration;
step (5), combining comprehensive solving information of a natural gas system and an electric power system, constructing a steady state analysis comprehensive solving model of the electric power-natural gas regional comprehensive energy system, and firstly reading in external environment information; outputting variables to be solved of the natural gas system and a pressure-load sensitivity matrix of the natural gas system according to the initialization part and the solving part of the natural gas system; analyzing an energy coupling link taking an energy concentrator as a core, and performing numerical value conversion on energy interaction of coupling equipment; finally, substituting the information into the calculation process of the power system, and if the calculation results of the power system are all in the reasonable operation interval of the system, finishing the calculation and outputting the result; otherwise, returning to the energy coupling link and adjusting the energy coupling link, and ensuring that the power system operates within a reasonable range through loop iteration; therefore, the influence of the change of the network state of the natural gas system on the natural gas system and the regional comprehensive energy system is obtained.
2. The steady-state analysis method for the power-natural gas regional integrated energy system according to claim 1, wherein the process of solving the natural gas system in the power-natural gas regional integrated energy system specifically comprises the following steps:
initialization: determining relevant parameters required by solving a natural gas system according to the natural gas network state;
by using the thought of graph theory, an incidence matrix A of nodes and branches for showing network topology information is constructed, and an element A of the incidence matrix AijAs defined below:
Figure FDA0002565844330000031
a natural gas system is described, with the formula:
Figure FDA0002565844330000032
Figure FDA0002565844330000033
wherein the content of the first and second substances,
Figure FDA0002565844330000034
in order to know the pressure at the node point,
Figure FDA0002565844330000035
in order for the pressure at the node to be unknown,
Figure FDA0002565844330000036
representing a pipeline flow equation determined according to a natural gas flow formula;
Figure FDA0002565844330000037
in order to be the net load capacity,
Figure FDA0002565844330000038
and
Figure FDA0002565844330000039
respectively measuring the natural gas injection amount and the natural gas consumption amount of a certain node; the above equation characterizes the meaning that the amount of natural gas flowing into a node is equal to the amount flowing out of the node plus the net load at the node; at the moment, the natural gas flow problem is further expressed as that the flow of a node with known pressure and the pressure of the node with known flow are obtained according to the known information;
solving the load flow by using a Newton method in power system load flow analysis for reference, and expressing an error equation F as follows:
Figure FDA00025658443300000310
the jacobian matrix J for constructing a natural gas system is as follows:
Figure FDA00025658443300000311
wherein p isiAnd pjRepresenting node pressure, qijThe pipeline flow under the standard condition; a. the1To eliminate reduced correlation matrices outside the pressure-known nodes, A1 TIs A1The transposed matrix of (2);
Figure FDA00025658443300000312
pressure at an unknown node;
and repeatedly iterating the pressure value of the natural gas system by constructing the Jacobian matrix and applying a Newton-Raphson method until the value of the error equation is smaller than the convergence standard, and outputting a trend result.
CN201611192565.XA 2016-12-21 2016-12-21 Steady state analysis method of electric power-natural gas regional comprehensive energy system Active CN106777708B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201611192565.XA CN106777708B (en) 2016-12-21 2016-12-21 Steady state analysis method of electric power-natural gas regional comprehensive energy system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201611192565.XA CN106777708B (en) 2016-12-21 2016-12-21 Steady state analysis method of electric power-natural gas regional comprehensive energy system

Publications (2)

Publication Number Publication Date
CN106777708A CN106777708A (en) 2017-05-31
CN106777708B true CN106777708B (en) 2021-02-05

Family

ID=58896942

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201611192565.XA Active CN106777708B (en) 2016-12-21 2016-12-21 Steady state analysis method of electric power-natural gas regional comprehensive energy system

Country Status (1)

Country Link
CN (1) CN106777708B (en)

Families Citing this family (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107508326B (en) * 2017-08-25 2019-08-20 广东电网有限责任公司电力调度控制中心 The emergency combined scheduling method and device of natural gas system and electric system
CN107563674B (en) * 2017-10-09 2020-07-10 清华大学 Electric-thermal coupling system state estimation method considering pipeline dynamic characteristics
CN107665384B (en) * 2017-10-27 2021-02-19 天津大学 Electric power-thermal power comprehensive energy system scheduling method containing multi-region energy station
CN108053104A (en) * 2017-12-06 2018-05-18 天津大学 Region electric power-natural gas-heating power integrated energy system energy stream optimization method
CN108416507B (en) * 2018-02-07 2021-08-20 天津大学 Static sensitivity analysis method for electricity-gas coupling comprehensive energy system
CN109063925B (en) * 2018-08-16 2021-08-17 合肥工业大学 Optimized operation method for regional comprehensive energy system considering load aggregators
CN109492325B (en) * 2018-11-29 2023-03-10 东北大学 Flow analysis method of multi-energy coupling system based on extended energy concentrator
CN109918795A (en) * 2019-03-11 2019-06-21 长沙理工大学 A kind of energy hinge canonical matrix Steady state modeling method for taking into account physical property and reliability
CN110112781A (en) * 2019-05-17 2019-08-09 河海大学 A kind of comprehensive energy electric system distribution interconnection modeling and analysis methods
CN110533277B (en) * 2019-07-14 2023-04-18 太原理工大学 Stability analysis method of electric-gas coupling comprehensive energy system based on N-1 fault
CN110489930B (en) * 2019-09-10 2023-09-01 南方电网科学研究院有限责任公司 Natural gas network steady-state analysis method, device, equipment and storage medium
CN110619487B (en) * 2019-10-12 2023-01-17 东北大学 Electric-gas-thermal coupling network dynamic state estimation method based on Kalman filtering
CN110717633A (en) * 2019-10-21 2020-01-21 国网重庆市电力公司电力科学研究院 Electric power and natural gas energy complementary optimization method and device and readable storage medium
CN110707705B (en) * 2019-10-22 2023-01-17 太原理工大学 Power flow sequence analysis model of electric-gas coupling comprehensive energy system
CN110866213A (en) * 2019-11-04 2020-03-06 中国电力科学研究院有限公司 Multi-network steady-state energy flow analysis method and device for electricity-gas integrated energy system
CN111259547B (en) * 2020-01-16 2021-12-03 清华大学 Natural gas path modeling method for operation control of comprehensive energy system
CN111767660A (en) * 2020-09-02 2020-10-13 国网江西省电力有限公司电力科学研究院 Optimal arrangement method and device for gas storage devices of electric coupling energy system
CN112257355A (en) * 2020-10-30 2021-01-22 东南大学 Modeling method for medium-low pressure gas distribution pipe network of hydrogen-doped natural gas
CN112330493B (en) * 2020-11-24 2022-10-28 南方电网科学研究院有限责任公司 Energy system modeling and comprehensive analysis method, device and storage medium
CN112818492B (en) * 2021-02-02 2022-12-02 山东大学 Electric-gas coupling network energy flow solving method considering state variables of energy source station
CN112986731B (en) * 2021-02-08 2022-12-02 天津大学 Electrical interconnection system toughness assessment and improvement method considering seismic uncertainty
CN114462163B (en) * 2022-01-26 2022-09-30 天津大学 exergy hub model considering energy quality
CN114285037B (en) * 2022-03-07 2022-05-27 天津大学 Method for determining control parameter stability region of regional electricity-gas integrated energy system
CN115935711B (en) * 2023-01-31 2023-10-20 西华大学 Multi-energy complementary active distribution network system reliability assessment method based on graph theory

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104734155B (en) * 2015-04-14 2017-03-01 河海大学 A kind of method obtaining electrical interconnection energy resource system available transmission capacity
CN105356447B (en) * 2015-10-27 2018-01-19 河海大学 A kind of electrical interconnection integrated energy system Analysis of Steady-state Security Region method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
M.Abeysekera等.Steady state analysis of gas networks with distributed injection of alternative gas.《Applied Energy》.2016,第164卷 *

Also Published As

Publication number Publication date
CN106777708A (en) 2017-05-31

Similar Documents

Publication Publication Date Title
CN106777708B (en) Steady state analysis method of electric power-natural gas regional comprehensive energy system
CN109242365B (en) Interval power flow calculation method of electricity-heat interconnection comprehensive energy system
Yao et al. Dynamic optimal energy flow in the heat and electricity integrated energy system
Franco et al. A network flow model for short-term hydro-dominated hydrothermal scheduling problems
Injeti et al. Optimal planning of distributed generation for improved voltage stability and loss reduction
CN112016033B (en) Electric-thermal-gas comprehensive energy system tide calculation method based on forward-push back substitution method
CN103219743B (en) Pilot node selecting method based on wind electric power fluctuation probability characters
CN108416507B (en) Static sensitivity analysis method for electricity-gas coupling comprehensive energy system
CN111428351B (en) Electric-thermal comprehensive energy system tide calculation method based on forward-push back substitution method
Kou et al. Many-objective optimization for coordinated operation of integrated electricity and gas network
CN111681130A (en) Comprehensive energy system optimization scheduling method considering condition risk value
Kamyar et al. Optimal thermostat programming for time-of-use and demand charges with thermal energy storage and optimal pricing for regulated utilities
CN105930980B (en) A kind of electricity turns the integrated energy system linear multi likelihood energy stream method of gas
He et al. Economic dispatch analysis of regional Electricity–Gas system integrated with distributed gas injection
CN115017854A (en) Method for calculating maximum allowable capacity of DG (distributed generation) of power distribution network based on multidimensional evaluation index system
CN110532642A (en) A kind of calculation method that integrated energy system probability can flow
CN115392035A (en) Improvement method for optimizing and scheduling electric-gas interconnection comprehensive energy system
Hu et al. Topological partition based multi-energy flow calculation method for complex integrated energy systems
Xiao et al. Optimal sizing and siting of soft open point for improving the three phase unbalance of the distribution network
Sun et al. Multi-energy flow calculation method for we-energy based energy internet
CN107465195B (en) Optimal power flow double-layer iteration method based on micro-grid combined power flow calculation
CN111293687A (en) Three-dimensional particle swarm algorithm-based distributed power supply location and volume determination method
CN111476394A (en) Robust operation optimization method suitable for multi-energy systems such as electric, thermal and the like
CN109672197A (en) A kind of probabilistic storage energy operation optimization method of consideration distributed generation resource power output
CN110020506A (en) Difference scheme selection method based on electroheating type integrated energy system running optimizatin

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CP02 Change in the address of a patent holder

Address after: 300452 Binhai Industrial Research Institute Campus of Tianjin University, No. 48 Jialingjiang Road, Binhai New Area, Tianjin

Patentee after: Tianjin University

Address before: 300072 Tianjin City, Nankai District Wei Jin Road No. 92

Patentee before: Tianjin University

CP02 Change in the address of a patent holder