CN107887912B - Static power flow analysis method and static power flow analysis system - Google Patents

Static power flow analysis method and static power flow analysis system Download PDF

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CN107887912B
CN107887912B CN201711342451.3A CN201711342451A CN107887912B CN 107887912 B CN107887912 B CN 107887912B CN 201711342451 A CN201711342451 A CN 201711342451A CN 107887912 B CN107887912 B CN 107887912B
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孙宏斌
夏天
郭庆来
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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Abstract

The invention provides a static power flow analysis method for a multi-energy complementary comprehensive energy system, which can effectively support system-level analysis and calculation by constructing a static power flow model of the multi-energy complementary comprehensive energy system and solving a network analysis on a multi-energy coupling system by adopting a hybrid iterative algorithm. The invention also provides a static power flow analysis system for the multi-energy complementary comprehensive energy system, which utilizes and greatly expands the calculation function of the existing mature power system simulation software and has openness and expandability.

Description

Static power flow analysis method and static power flow analysis system
Technical Field
The invention belongs to the field of energy Internet, and relates to a static power flow analysis method and a static power flow analysis system for a multi-energy complementary comprehensive energy system.
Background
In recent years, a third industrial revolution characterized by the energy internet has been awaited. The energy Internet is characterized in that a power grid is used as a main body and a platform, and coupling complementation of various energy forms is carried out. The network analysis of the multi-energy coupling system is one of important research contents in the field of energy Internet, is the calculation basis and foundation for system planning, operation regulation and control and energy trading, and not only needs to consider respective energy conversion complementation of an energy supply side and an energy utilization side in the system, but also needs to consider the network balance of the multi-energy system. At present, in respective fields of traditional electricity, heat, gas and the like, analysis methods of systems are relatively mature, for example, a power system adopts load flow calculation; the thermodynamic system follows fluid and thermodynamic laws and is calculated by two equations of simultaneous water power (or steam) and heat power; the natural gas system follows the law of fluid mechanics, and the fluid mechanics equation is used for representing and calculating. In addition, with the large construction of renewable energy sources/clean energy sources such as fans, photovoltaics, CHP/CCHP and the like, the rising of active distribution networks and intelligent micro-grids, more modeling and simulation methods aiming at single equipment and small power networks are provided, and corresponding mathematical models are provided for the comprehensive utilization of a plurality of energy forms in part of micro-grid systems. Most of the models consider point balance such as energy, momentum, mass and the like mainly from the viewpoint of equipment, but do not consider network balance, and are not suitable for system-level analysis and calculation.
In contrast, documents [1] and [2] respectively study combined power flow analysis of a power grid, a natural gas network and a heat supply network, documents [3] and [4] use a network flow model to perform simulation analysis on coal, natural gas and the power grid in the united states, and these documents consider network balance and the multi-energy characteristics of the system from the system perspective, wherein the power grid part mainly considers some typical devices in the traditional alternating current power grid, and the calculation method is mainly based on the traditional newton-raphson method, and the method is not described in the prior art for complex situations that the types of power grid devices are various (such as a new energy electric field, FACTS devices and the like) or an alternating current-direct current hybrid power grid structure is adopted, and in addition, a method that a user can develop a model and access the calculation by himself is not mentioned in the prior art.
On the other hand, professional simulation software is currently used in the respective fields of electricity and heat for auxiliary analysis, such as PSASP, BPA, PSCAD and the like in the electric field, and Thermoflow, Ansys, Cycle-Tempo and the like in the heat field, but the software does not consider the coupling between multiple functions except the self field.
[1]Martinez-Mares A,Fuerte-Esquivel C R.A Unified Gas and Power FlowAnalysis in Natural Gas and Electricity Coupled Networks[J]. IEEETransactions on Power Systems,2012,27(4):2156-2166.
[2]X Liu,N Jenkins,J Wu,et al.Combined Analysis of Electricity andHeat Networks.Energy Procedia,2014,61:155-159.Liu X.Combined Analysis ofElectricity and Heat Networks[D].Cardiff University Institute of Energy,2013.
[3]Quelhas A,Gil E,McCalley J D,et al.A Multiperiod GeneralizedNetwork Flow Model of the U.S.Integrated Energy System:Part I—ModelDescription[J].IEEE Transactions on Power Systems,2007,22(2):829-836.
[4]Quelhas A,McCalley J D.A Multiperiod Generalized Network FlowModel of the U.S.Integrated Energy System:Part II—Simulation Results[J].IEEETransactions on Power Systems,2007,22(2):837-844.
Disclosure of Invention
In view of the above, the invention provides a static power flow analysis method and a static power flow analysis system for a multi-energy complementary comprehensive energy system, which can effectively support system-level analysis and calculation by constructing a static power flow model of the multi-energy complementary comprehensive energy system and solving a network analysis on the multi-energy coupling system by adopting a hybrid solution algorithm.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a static power flow analysis method for a multi-energy complementary comprehensive energy system comprises the following steps:
firstly, performing network topology analysis on a non-electric system abstract diagram based on a diagram theory to construct a non-electric system power flow model;
step two, constructing a power flow model of the power system;
representing each coupling device by using a power output external characteristic equation, and constructing a coupling device operation external characteristic model for coupling between a non-electric system and an electric power system;
step four, establishing a non-electric system power flow model in the step one, a power system power flow model in the step two and a coupling device operation external characteristic model in the step three in a simultaneous manner, and constructing a static power flow model of the multi-energy complementary comprehensive energy system;
and step five, solving the static power flow model of the four-energy complementary comprehensive energy system by adopting a hybrid solving algorithm, wherein the hybrid solving algorithm means that the non-electric system power flow model and the electric power system power flow model are respectively solved by using different iterative algorithms.
Furthermore, in the first step, directed edges of a graph corresponding to a pipeline in the non-electric system and connecting pieces correspond to vertexes of the graph, each pipeline section defines a positive flow direction, a matrix of the graph describes a topological structure of the non-electric system, and a valve is used as an attached attribute of the pipeline to be calculated.
Further, the non-electrical system power flow model is as follows:
Figure GDA0002541885840000031
wherein A is a correlation matrix, Au、AdRespectively an upper and a lower correlation matrix, BfIs a loop matrix. M is B orderThe flow column vector of the pipeline, Q is the flow column vector of the inflow of the N-stage nodes, Δ H is the column vector of the differential pressure of the B-stage pipeline, Z is the column vector of the height difference of the head and tail end nodes of the B-stage pipeline, TeIs the column vector (DEG C) of the tail end temperature of the B-stage pipeline, TnIs an N-order node temperature column vector (DEG C), QJIs the N-th order node heat load column vector, TaIs a B-order ambient temperature array vector (DEG C), E is a B-order temperature attenuation coefficient diagonal matrix, S is a B-order pipeline resistance coefficient array vector, HpIs the pump head column vector, HvIs the column vector of the pressure difference on two sides of the valve.
Further, a pump head column vector H in the non-electric system power flow modelpThe calculation formula of the constituent elements is as follows:
Figure GDA0002541885840000032
Figure GDA0002541885840000033
wherein h isiIs a coefficient, m is the pipe flow,
Figure GDA0002541885840000034
for each pump head on the pipeline, belonging to HpColumn vector constituent elements, n0Is the rated speed of the pump motor shaft, n is the actual speed, hi.n0Is the coefficient of the pump motor at the rated rotating speed;
differential pressure column vector H on two sides of valvevThe calculation formula of the constituent elements is as follows:
Figure GDA0002541885840000041
wherein
Figure GDA0002541885840000042
Is the pressure difference between two sides of a valve on a pipeline and belongs to HvColumn vector component elements, ξ is the reciprocal of the valve opening, d is the pipe diameter (m), ρ is the fluid working medium density (kg/m3), and m is the pipe flow.
Further, the external characteristic model of the coupling equipment for coupling between the non-electric system and the electric power system is as follows:
Figure GDA0002541885840000043
wherein, PG*、QGRespectively as electric and thermal powers, P, of combined-supply unitpElectrical pump power, η pump efficiency, m fluid flow in the pump, HpIs pump head, Qhp*、Qeb*、QcRespectively the thermal powers of heat pump, electric boiler and refrigerating machine, Php*、Peb*、PcThe power of the heat pump, the electric boiler and the refrigerator.
Further, the static power flow model of the multi-energy complementary comprehensive energy system is as follows:
Figure GDA0002541885840000044
wherein, Fe0 denotes a step two power system power flow model, FhStep one non-electrical system power flow model, F, is represented by 0ehAnd 0 represents an external characteristic model of the step three-coupling equipment, and F0 represents a static power flow model of the multi-energy complementary comprehensive energy system.
Further, the hybrid solution algorithm comprises the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix;
(2) initializing the state quantity X of the power system of the random distribution coupling equipment when the number of the initialization iterations k is equal to 0e (k)And a non-electrical system state quantity Xh (k)；
(3) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (4); otherwise, the calculation is finished;
(4) coupling device electric power P according to post-convergence coupling devicee (k)Operating the external characteristic model to the non-electric system state by utilizing the step three-coupling equipmentQuantity Xh (k)Corrected and recorded as Xh’ (k)；
(5) According to the corrected non-electric system state quantity Xh’ (k)Carrying out non-electric system load flow calculation; then judging whether the non-electric system load flow calculation is converged, if so, jumping to the step (6), otherwise, finishing the calculation;
(6) calculating convergence result X according to non-electric system load flowh’ (k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’ (k)(ii) a Then judging whether | Pe’ (k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (3) is returned after k + 1.
Further, when the non-electric system comprises n energy forms, n is more than or equal to 2; the hybrid solution algorithm comprises the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix of each non-electric system;
(2) initializing the state quantity X of the power system of the random distribution coupling equipment when the number of the initialization iterations k is equal to 0e (k)And a non-electrical system state quantity Xh (k)、Xc (k)；
(3) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (4); otherwise, the calculation is finished;
(4) according to the electric power P of the coupling device after convergencee (k)Utilizing the step three coupling equipment to operate the external characteristic model to the ith energy form state quantity Xh (k)Corrected and recorded as Xh’ (k)Wherein i is 1;
(5) according to the corrected state quantity X of the first energy formh’ (k)Carrying out load flow calculation; then judging whether the load flow calculation is converged, if so, jumping to the step (6), otherwise, finishing the calculation;
(6) according to the ith energy form state quantity X after convergenceh’ (k)And couplingPlant electric power Pe (k)Utilizing the step three coupling equipment to operate the external characteristic model to the (i + 1) th energy form state quantity Xc (k)Corrected and recorded as Xc’ (k)；
(7) According to the corrected i +1 energy form state quantity Xc’ (k)Carrying out load flow calculation; then judging whether the load flow calculation is converged, if so, jumping to the step (8), otherwise, finishing the calculation;
(8) repeating steps (6) and (7) until i ═ n-1;
(9) calculating convergence result X according to load flow of n energy formsh’ (k)、Xc’ (k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’ (k)(ii) a Then judging whether | Pe’ (k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (3) is returned after k + 1.
Further, the load flow calculation of each energy form of the non-electric system of the hybrid solution algorithm comprises the following steps:
(a) initializing the number of iterations t to 0, and initializing the non-electric system state quantity X(t)＝Xh (k)；
(b) According to the non-electric system state quantity X(t)Calculating a B-order temperature attenuation coefficient diagonal array E and a B-order pipeline resistance coefficient column vector S according to the parameter values, and converting the B-order temperature attenuation coefficient diagonal array E and the B-order pipeline resistance coefficient column vector S into fixed values;
let S be an element in the pipeline resistance characteristic coefficient S, that is, a resistance coefficient on a certain pipeline, and the calculation formula is as follows:
Figure GDA0002541885840000061
wherein L is the length (m) of the pipeline, D is the diameter (m) of the pipeline, and rho is the density (kg/m) of the fluid working medium in the pipeline3) G is the acceleration of gravity (kg. m/s)2) K is a correction coefficient, and f is a pipeline friction coefficient;
the calculation formula of the B-order temperature attenuation coefficient diagonal matrix E is as follows:
Figure GDA0002541885840000062
wherein λ isi，Li，cpiAnd miRespectively representing the thermal conductivity, the length of the pipeline, the specific heat capacity of fluid working medium in the pipeline and the flow rate of the pipeline of the unit length of the ith pipeline, wherein i is more than or equal to 1 and less than or equal to B;
(c) and (3) expressing the non-electric system power flow model in the step one by using a functional relation as follows:
F(X)＝0；
wherein, F is an error function, and a Jacobian matrix J of the system is defined as:
Figure GDA0002541885840000063
calculating a Jacobian matrix J;
(d) updating X(t+1)＝X(t)-J \ F, then determine if | X(t+1)-X(t)I < or t > tmaxWherein, tmaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (b) is returned after t + 1.
The invention also provides a static power flow analysis system adopting the multi-energy complementary comprehensive energy system, which comprises a power analysis module, a non-power analysis module and a coupling analysis module, wherein the non-power analysis module is used for realizing the power flow calculation of the power flow model of the non-power system in the step I; and the power analysis module, the non-power analysis module and the coupling analysis module realize data interaction to solve the static power flow model of the multi-energy complementary comprehensive energy system in the fourth step and the fifth step.
Further, the power analysis module performs power module load flow calculation, electric power of the coupling equipment is transmitted into the coupling analysis module after calculation convergence, the coupling analysis module corrects the non-electric state quantity according to the electric power and transmits the non-electric state quantity to the non-power analysis module for non-electric load flow calculation, and the non-electric state quantity is transmitted to the coupling analysis module after convergence to recalculate electric power of the coupling device and transmits the electric power to the power analysis module; and if the power error of the coupling device obtained by the two previous and subsequent calculations meets the precision requirement, stopping the calculation, otherwise, refreshing the electric power of the coupling device in the power grid data of the electric power analysis module, and continuing the calculation.
Further, the non-power analysis module comprises two base classes of pipelines and nodes, on the basis, an equipment model class which comprises two base classes depending on the two base classes is designed and is used for referring to the same class of equipment, then a subclass model instance class of the equipment model class is designed and is used for referring to the actual equipment, a subclass model instance set class of the design model instance class is designed, and the set of each actual equipment model object is realized, so that the non-power analysis module is formed.
Furthermore, static power flow calculation of the non-power analysis module and the coupling analysis module is independently compiled into a dynamic link library file, and the file is called through a user program interface of the existing power system simulation analysis software to realize joint calculation; the existing power system simulation analysis software is used as a power analysis module.
Furthermore, existing power system simulation analysis software is independently compiled into an executable program as a power analysis module, and the program is executed to complete the joint calculation by being embedded into a static power flow calculation program of a non-power analysis system and a coupling analysis system.
Furthermore, a user establishes a self-defined transfer function mathematical model of the equipment through a graphical interface, the system automatically generates a model file, a dynamic link library program analyzes the model file and is internally provided with an algorithm, and mutual transfer and cooperative calculation of data are realized through an interface with a main program of the system.
The invention has the beneficial effects that:
(1) the method can effectively support the system-level analysis and calculation by constructing the static power flow model of the multi-energy complementary comprehensive energy system and adopting the hybrid solving algorithm to solve and carry out network analysis on the multi-energy coupling system.
(2) The invention adopts a mixed solving algorithm of different iteration methods aiming at different systems, for example, the power flow adopts an optimal multiplier method, the thermal flow adopts a Newton-Raphson method, the convergence is ensured, and the efficiency is not sacrificed.
(3) The invention adopts an embedded program development method, has openness and expandability, independently compiles the static power flow calculation of other energy form networks and coupling equipment into a dynamic link library file, and the power system simulation analysis software calls the file through a user program interface to realize joint calculation, or independently compiles the power system simulation analysis software into an executable program and executes the executable program by embedding the executable program into the static power flow calculation programs of the other energy form networks and the coupling equipment to complete the joint calculation.
(4) The method adopts a mode of calling a dynamic link library file to externally connect user-defined modeling, has openness and expandability, establishes a user-defined transfer function mathematical model of the equipment through a graphical interface, automatically generates a model file by a program, analyzes the model file by the dynamic link library program and embeds an algorithm, and realizes mutual transfer and cooperative calculation of data through an interface with a main program; the user-defined modeling adopts an object-oriented program architecture, and has openness and expandability.
(5) On one hand, the simulation of various power grid equipment including a direct current system, a new energy electric field, FACTS devices and the like can be performed by utilizing the calculation function of the existing mature power system simulation software, so that the workload of program development is reduced, and meanwhile, a more advanced calculation method can be adopted, so that the convergence and the reliability of calculation are ensured; on the other hand, the simulation software function of the power system is expanded, so that the simulation calculation of the multi-energy coupling system can be carried out; on the other hand, the multi-energy coupling system can be further subjected to steady-state or dynamic analysis on the basis of combined load flow calculation by relying on a powerful model library of power system simulation software, and the multi-energy coupling system has openness and expandability, so that a user-defined model can be further developed on the basis to participate in simulation calculation by a person skilled in the art, and the simulation analysis capability of the comprehensive energy system is greatly expanded.
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The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 is a static power flow calculation process (taking an electric heating coupling system as an example) of the multi-energy complementary comprehensive energy system provided by the invention;
FIG. 2 is a flow chart of static load flow calculation of the non-electric system according to the present invention;
FIG. 3 illustrates classes and relationships of the non-electrical system based on an object-oriented programming architecture according to the present invention;
FIG. 4 is a calculation flow of the case where the main program provided by the present invention is accessed to the custom model;
fig. 5 is a topology structure diagram of a 6-bus power system provided in an embodiment of the present invention;
fig. 6 is a topological structure diagram of a cold network system according to an embodiment of the present invention;
fig. 7 is a topology structure diagram of a heat supply network system according to an embodiment of the present invention;
FIG. 8 is a diagram illustrating the effect of the hybrid iterative solution algorithm provided by the embodiment of the present invention;
FIG. 9 is a graph of a heat supply network node temperature profile;
FIG. 10 is a cold net node distribution diagram;
fig. 11 is a grid node distribution diagram.
Detailed Description
The present invention will be described below based on examples, but the present invention is not limited to only these examples.
The invention provides a static power flow analysis method for a multi-energy complementary comprehensive energy system, which realizes network analysis of the multi-energy coupling system by calculating the static power flow of the multi-energy coupling system constructed by a heat, gas, cold and other non-electric system and an electric system. The method specifically comprises the following steps:
the method comprises the following steps: building non-electric system power flow model
For convenience of description, the static power flow analysis method embodiment of the present invention only describes the non-electrical system power flow model provided by the present invention by taking the heat supply network as an example, and the non-electrical systems such as the air and cold networks are similar to the heat supply network structure, and those skilled in the art can easily extend the non-electrical system power flow model provided by the present invention to other non-electrical systems such as the air network and cold networks.
The invention discloses a heat distribution network, which mainly comprises heat distribution pipelines and connecting pieces, wherein a heat distribution system is abstracted into a graph to perform network topology analysis based on graph theory, wherein the heat distribution pipelines correspond to directed edges of the graph, the connecting pieces (heat sources, heat loads and pipeline connecting pieces) correspond to vertexes of the graph, valves are used as the accessory attributes of the pipelines, each pipeline section defines the positive flow direction, for example, the flow direction of fluid during heat distribution network design is taken, and therefore, the topological structure of the heat distribution system can be described by using a matrix of the graph. The topological structure of the thermodynamic system comprises N nodes and B pipelines, and after the heat supply network is abstracted, a heat supply network incidence matrix A and an upper incidence matrix A can be obtaineduLower correlation matrix AdAnd loop matrix Bf。
And then respectively carrying out fluid mechanics modeling and thermal working condition modeling on the heat supply network, respectively constructing a fluid mechanics steady-state equation (formula 1-3) of a thermal system and a thermal working condition steady-state equation (formula 4-5), and obtaining a static power flow model of the heat supply network by combining the fluid mechanics steady-state equation and the thermal working condition steady-state equation as shown in formula 1-5.
Figure GDA0002541885840000091
Wherein A is a heat supply network incidence matrix, Au、AdRespectively an upper and a lower correlation matrix, BfIs a loop matrix. M is a flow column vector of a B-stage pipeline, Q is an inflow flow column vector of an N-stage node, Delta H is a differential pressure column vector of the B-stage pipeline, Z is a height difference column vector of a head-end node and a tail-end node of the B-stage pipeline, TeIs the column vector (DEG C) of the tail end temperature of the B-stage pipeline, TnIs an N-order node temperature column vector (DEG C), QJIs the N-th order node heat load column vector, TaIs a B-order ambient temperature array vector (DEG C), E is a B-order temperature attenuation coefficient diagonal matrix, and S is a B-order pipeline resistance coefficient array vector. T ise、Tn、TaThe other state quantities are per unit values for named values.
HpIs a column vector of pump head per unit value, HvIs the column vector of the pressure difference per unit value on two sides of the valve.
Wherein:
Figure GDA0002541885840000101
Figure GDA0002541885840000102
hiis coefficient, m is per unit value of pipe flow,
Figure GDA0002541885840000103
is the per unit value of each pump lift on the pipeline, belonging to HpColumn vector constituent elements, n0Is the rated speed of the pump motor shaft, n is the actual speed, hi.n0Is the coefficient at the rated speed of the pump motor.
Figure GDA0002541885840000104
Figure GDA0002541885840000105
Is the per unit value of the pressure difference between two sides of the valve on the pipeline, belonging to HvColumn vector component elements, ξ is the reciprocal of the valve opening, d is the pipe diameter (m), ρ is the fluid working medium density (kg/m3), and m is the per unit value of the pipeline flow.
In the calculation of the formulas 3 and 8, the valve is used as the accessory attribute of the pipeline in the model, the number of elements is not increased in the calculation, and the calculation is simplified.
Step two: construction of power flow model of electric power system
The power system load flow model adopted by the invention is the prior art, the current power system load flow model and calculation are relatively mature, and many mature power system simulation software appears, such as PSASP software developed by China department of Electrical sciences, BPA software developed by American EPRI, and the like, and the description is not repeated, and only the power system load flow model formula for the common power system is listed.
Figure GDA0002541885840000111
Figure GDA0002541885840000112
Wherein, Pi、QiInjecting active and reactive power, G, respectively, for a network node i of the power systemij、BijRespectively the mutual conductance and the mutual susceptance between the nodes i and j,ijrepresenting the phase angle difference between nodes i, j, U being the node voltage. The above are per unit values.
Step three: constructing an equipment operation external characteristic model for coupling between a non-electric system and an electric power system
The construction of a coupling equipment model for coupling between a non-electric system and an electric system is the premise and the basis for carrying out load flow unified calculation, and an electrothermal coupling device generally comprises a combined supply unit, a water pump, a heat pump, an electric boiler, a refrigerator and the like by taking electrothermal coupling as an example. The working mechanisms in the devices are different and complex, but for the calculation of the power grid and non-electric system coupling power flows, the relation between the power grid power flow and the non-electric system power flow can be established by representing each coupling device by using a power output external characteristic equation, so that the combined solution is realized. The model is represented by the following formula, the model covers the description of all coupling equipment of electricity and non-electricity, and corresponding model calculation is carried out according to the selection of an actual coupling device in the calculation.
Figure GDA0002541885840000113
Wherein, PG*、QGRespectively as electric and thermal powers, P, of combined-supply unitpElectrical pump power, η pump efficiency, m fluid flow in the pump, HpIs pump head, Qhp*、Qeb*、QcRespectively the thermal powers of heat pump, electric boiler and refrigerating machine, Php*、Peb*、PcThe power of the heat pump, the electric boiler and the refrigerator. The above are per unit values.
Step four: static power flow model for constructing multi-energy complementary comprehensive energy system
And (3) establishing a non-electric system power flow model in the step one, a power system power flow model in the step two and a coupling equipment operation external characteristic model in the step three in a simultaneous manner, and constructing a static power flow model of the multi-energy complementary comprehensive energy system as shown in the following.
Figure GDA0002541885840000121
Wherein, FeThe power flow model of the power system is represented by 0, F h0 denotes the non-electrical system power flow model, FehAnd 0 represents an external characteristic model of the operation of the coupling equipment, and 0 represents a static power flow model of the multi-energy complementary comprehensive energy system.
Step five: solving the static power flow model of the multi-energy complementary comprehensive energy system by adopting a hybrid solving algorithm
The power system and the non-power system have obvious differences in system composition, operation mechanism, response time scale, output characteristic and the like, and the system control in the actual operation process is relatively independent. Taking electrothermal coupling as an example, the electric and thermal parts are related by electrothermal coupling equipment, and the two parts are in a loose coupling relationship. Therefore, according to the characteristic that the power system is coupled with the non-power system, in the specific calculation process, the two parts do not need to be jointly solved in one iteration, the calculation can be independently carried out, only after the power flow or the non-power flow is converged, the adjustment of partial state quantity is carried out according to the output characteristic equation of the coupling device, then the iterative calculation of the other energy flow is carried out, and the iteration is carried out, so that the integral convergence is achieved. By the method, the problems of poor calculation convergence, long time consumption and more occupied computer memory space of the power system and the non-power system as a whole can be solved, and the computer program is easy to design and implement.
Furthermore, the hybrid solution algorithm is carried out by adopting different iteration methods for different systems, for example, when the electric thermocouple is coupled, the optimal multiplier method is adopted for the calculation of the power system, and the Newton-Raphson method is adopted for the calculation of the heat network, so that the faster convergence can be realized.
The static power flow calculation process of the multi-energy complementary comprehensive energy system provided by the invention is shown in fig. 1, and an electrothermal coupling system is taken as an example for explanation. The method specifically comprises the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix (such as a heat supply network incidence matrix A and an upper incidence matrix A in the step one)uLower correlation matrix AdAnd loop matrix BfEtc.);
(2) performing data per unit processing on the model calculation data so as to finish the preparation of the calculation data;
(3) initializing the coupling equipment power system state quantity X when the number of initialization iterations k is equal to 0e (k)＝[PT,QT,UT,T]T(character definition in step two) and non-electric system state quantity Xh (k)＝[M*T, Q*T,ΔH*T,Te T,Tn T,QJ*T]T(the character definition is shown in step one) is a per unit value, and the initial value is randomly distributed.
(4) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (5); otherwise, the calculation is finished;
(5) according to the electric power P of the coupling device after convergencee (k)＝[PG*T,Pp*T,Php*T,Peb*T, Pc*T]T(see step 3 for character definition), the non-electric system state quantity X is calculated by using the formulas (11) - (13)h (k)Corrected and recorded as Xh’ (k)；
(6) According to the corrected non-electric system state quantity Xh’ (k)Carrying out load flow calculation on the thermodynamic system; then judging whether the thermodynamic system load flow calculation is converged, if so, jumping to the step (7), otherwise, finishing the calculation;
(7) calculating convergence result X according to load flow of thermodynamic systemh’ (k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’ (k)(ii) a Then judging whether | Pe’ (k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (4) is returned after k + 1.
In conclusion, the method firstly carries out the power flow calculation of the power system in the step two, after the calculation is converged, the electric power result of the electric heating coupling device is used for correcting the state quantity of the heat supply network through the external characteristic model operated by the coupling equipment in the step three, then carries out the power flow calculation of the heat supply network, and after the calculation is converged, recalculates the electric power of the electric heating coupling device according to the external characteristic model operated by the coupling equipment in the step three and sends the electric power to the power system for power flow calculation. And if the power error of the coupling device obtained by the two previous and subsequent calculations meets the precision requirement, stopping the calculation, otherwise, refreshing the electric power of the electrothermal coupling device and continuing the calculation.
The power flow calculation of the power system can be completed by existing mature power system simulation software, such as PSASP software developed by China department of Electrical sciences, BPA software developed by American EPRI, and the like, and is not described herein again.
Furthermore, the non-electric system can be in any energy form of non-electric energy sources such as heat, cold and gas, for example, the heat supply network, so that the electric-heat coupling is realized.
For each energy form, a specific flow calculation flow provided by the invention is shown in fig. 2 (taking a heat supply network as an example), and specifically comprises the following steps:
(a) initializing the state quantity X of the thermodynamic system when the number of the initialization iterations t is equal to 0(t)＝Xh’ (k)。
(b) According to thermodynamic system state quantity X(t)Calculating a B-order temperature attenuation coefficient diagonal array E and a B-order pipeline resistance coefficient column vector S according to the parameter values, and converting the B-order temperature attenuation coefficient diagonal array E and the B-order pipeline resistance coefficient column vector S into fixed values;
let S be an element in the pipeline resistance characteristic coefficient S, that is, a resistance coefficient on a certain pipeline, and the relationship between the pressure loss Δ h on the pipeline and the pipeline flow m (kg/S) is as follows:
Δh＝sm|m (15)
wherein, the resistance coefficient s can be obtained by calculating the friction coefficient f of the pipeline, and the formula is as follows:
Figure GDA0002541885840000141
wherein L is the length (m) of the pipeline, D is the diameter (m) of the pipeline, and rho is the density (kg/m) of the fluid working medium in the pipeline3) G is the acceleration of gravity (kg. m/s)2). k is a correction coefficient under the influence of local loss of the pipeline, and the k can be 1.1-1.3 for a long pipeline.
The friction coefficient f of the pipe is related to the reynolds number Re, the calculation of the reynolds number (a function of the flow m) and the calculation of f from the reynolds number by means of a piecewise function are well known in the prior art and can be found in the fluid mechanics textbook.
The temperature decay coefficient E is expressed as follows:
Figure GDA0002541885840000142
wherein λ isi，Li，cpiAnd miRespectively representing the thermal conductivity (W/(m.K)) of the unit length of the ith pipeline, the length (m) of the pipeline, the specific heat capacity (J/(kg.K)) of a fluid working medium in the pipeline and the flow (kg/s) of the pipeline; wherein i is more than or equal to 1 and less than or equal to B, and B is the number of pipelines.
In the step, the flow m of the pipeline is taken as a known quantity (m at the beginning)(0)Or m's calculated last time at the beginning of each iteration(k)) And (3) obtaining S, E by using m, and then using S, E as a known quantity to calculate a system state quantity in the power flow model in the iteration process.
(c) And (3) expressing the non-electric system power flow model in the step one by using a functional relation as follows:
F(X)＝0；
wherein F is an error function, and X is [ M ═ M%T,Q*T,ΔH*T,Te T,Tn T,QJ*T]T. The jacobian matrix J defining the system is:
Figure GDA0002541885840000143
the jacobian matrix J is calculated.
(d) Updating X(t+1)＝X(t)-J \ F, then determine if | X(t+1)-X(t)I < or t > tmaxWherein, tmaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (b) is returned after t + 1.
The non-electrical system of the present invention may also include at least two forms of energy coupling, such as hot and cold networks, to achieve electric-to-heat and cold coupling.
For convenience of description, the following description will be given by taking an example including two energy forms, a hot network and a cold network, i.e., an electric-thermal-cold coupling, where the static power flow calculation process of the multi-energy complementary integrated energy system includes the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix of each non-electric system;
(2) initializing the state quantity X of the power system of the random distribution coupling equipment when the number of the initialization iterations k is equal to 0e (k)And a non-electrical system state quantity Xh (k)、Xc (k)；
(3) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (4); otherwise, the calculation is finished;
(4) according to the electric power P of the coupling device after convergencee (k)Running an external characteristic model by using the step three-coupling equipment to carry out heat supply network state quantity Xh (k)Corrected and recorded as Xh’ (k)；
(5) According to corrected heat supply network state quantity Xh’ (k)Carrying out load flow calculation of the heat supply network; then judging whether the heat supply network load flow calculation is converged, if so, jumping to the step (6), otherwise, finishing the calculation;
(6) according to the converged heat supply network state quantity Xh’ (k)And coupling device electric power Pe (k)Running an external characteristic model by using the step three-coupling equipment to carry out state quantity X on the cold netc (k)Corrected and recorded as Xc’ (k)；
(7) According to the corrected cold net state quantity Xc’ (k)Carrying out load flow calculation of a non-electric system (cold network); then judging whether the cold network load flow calculation is converged, if so, jumping to the step (8), otherwise, finishing the calculation;
(8) calculating convergence result X according to non-electric system load flowh’ (k)、Xc’ (k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’ (k)(ii) a Then judging whether | Pe’ (k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (3) is returned after k + 1.
According to the flow, when the non-electric system comprises at least two energy forms, the non-electric system power flow calculation sequentially carries out power flow calculation on each energy form according to the corrected non-electric system state quantity, and the non-electric system state quantity is corrected by operating the external characteristic model through the three-step coupling equipment after the power flow calculation of each energy form is completed. The power flow calculation for each energy form is shown in fig. 2.
For convenience of data interaction, simplification of calculation, improvement of convergence and convenience of result analysis, the static load flow calculation in the present invention uses per unit values as described above, but the present invention is not limited to using per unit values, and includes other unit systems that can be easily conceived by those skilled in the art.
The invention also provides a static power flow analysis system for the multi-energy complementary comprehensive energy system, which comprises a power analysis module, a non-power analysis module and a coupling analysis module, wherein the non-power analysis module is used for realizing the power flow calculation of the power flow model of the non-power system in the step I, the power analysis module is used for realizing the power flow calculation of the power flow model of the power system in the step II, and the coupling analysis module is used for realizing the calculation of the external characteristic model of the operation of the coupling equipment between the non-power system and the power system.
And the power analysis module, the non-power analysis module and the coupling analysis module jointly realize the solving of the static power flow model of the multi-energy complementary comprehensive energy system in the fourth step and the fifth step. Specifically, the static power flow model parameters of the multi-energy complementary comprehensive energy system are read from the data file, and the static power flow calculation process of the multi-energy complementary comprehensive energy system is executed. The electric power analysis module carries out power module load flow calculation, electric power of the coupling equipment is transmitted into the coupling analysis module after calculation convergence, the coupling analysis module corrects state quantity of a heat supply network according to the electric power and transmits the state quantity to the non-electric power analysis module to carry out heat supply network load flow calculation, and the electric power is transmitted to the coupling analysis module to recalculate electric power of the electric heating coupling device and transmits the electric power to the electric power analysis module after convergence. And if the electric power error of the coupling device obtained by the two previous and subsequent calculations meets the precision requirement, stopping the calculation, otherwise, refreshing the electric power of the electric heating coupling device in the electric network data of the electric power analysis module, and continuing the calculation.
The non-power analysis module is based on the design concept of a C + + object-oriented program architecture, as shown in FIG. 3, and comprises two base classes, namely a pipeline (pipe) and a node (node), on the basis, an equipment model class which comprises two base classes is designed and comprises equipment models depending on the two base classes and is used for referring to the same class of equipment, then a subclass model instance class of the equipment model class is designed and refers to actual equipment, a subclass model instance set class of the model instance class is designed, and the collection of model objects of each actual equipment is realized, so that the non-power analysis module is formed.
The invention adopts an embedded program development method, static load flow calculation of a non-power analysis module and a coupling analysis module is independently compiled into a dynamic link library file, power system simulation analysis software calls the file through a user program interface to realize joint calculation, and the existing mature simulation analysis software can be adopted; existing power system simulation analysis software can also be independently compiled into an executable program, and the program is executed to complete the joint calculation by being embedded into a static power flow calculation program of a non-power analysis system and a coupling analysis system.
The mode of calling the dynamic link library file is adopted, the external connection of user-defined modeling can be realized, the openness and the expandability are realized, a user establishes a user-defined transfer function mathematical model of the equipment through a graphical interface, a program automatically generates the model file, the dynamic link library program analyzes the model file and is internally provided with an algorithm, and the mutual transfer and the cooperative calculation of data are realized through an interface with a main program.
Taking the power system simulation analysis software to call the dynamic link library file through the user program interface to realize the joint calculation, such as PSASP power system simulation analysis, the invention can utilize the function of the PSASP User Program Interface (UPI) to realize the compatibility of the PSASP with the user-defined non-power analysis system and the static power flow program module of the coupling analysis system, so that the PSASP becomes an open software package. The load flow calculation user program interface (LF/UPI) realizes the alternate operation of the power load flow calculation module and the user program module, and jointly completes a new task based on load flow calculation.
As shown in fig. 4, the calculation process for accessing the main program to the user-defined model includes: firstly, a main program (such as power analysis) completes the self load flow calculation process, after the convergence is judged to be achieved, a user-defined model (such as a non-power analysis system and coupling analysis) is called through a user interface, then the analysis, initial value assignment and load flow calculation process of the user-defined model are completed, if the calculation achieves the convergence, whether the constraint condition of program ending is met is judged, and if yes, the process is ended; otherwise, returning to the load flow calculation process of the main program; if convergence cannot be achieved, the procedure ends.
The embodiment of the invention comprises the following steps:
taking a 6-bus power system connected with a cold network and a hot network as an example, as shown in fig. 5, a bus 1 is connected with an external large power grid, buses 2 and 6 are respectively connected with two combined cooling heating and power units (hereinafter referred to as CCHP units), and buses 3, 4 and 5 are connected with loads; in addition, the bus 3 can be connected to a wind farm and the bus 4 can be connected to a photovoltaic power station. The network topology parameters of the power system are shown in table 1 and table 2:
TABLE 1 electric Power System line parameters
Figure GDA0002541885840000171
TABLE 2 Transformer parameters
Figure GDA0002541885840000172
As shown in fig. 6 and 7, the cold and hot networks are both 5-node systems, where nodes 5 and 4 are respectively connected to the two CCHP units in fig. 5 for cooling and heating, and nodes 1, 2 and 3 are connected to the cold and hot loads. The pipeline parameters are shown in table 3 (the water return pipeline parameters are symmetrical to the water supply pipeline):
TABLE 3 Cold/Heat network piping parameters
Figure GDA0002541885840000181
Thermoelectric ratio of CCHP unit:
the CCHP1 thermoelectric ratio is set to satisfy
Figure GDA0002541885840000182
CCHP2 thermoelectric ratio satisfying
Figure GDA0002541885840000183
Wherein phi1，Φ2Representing the heat power, P, of the CCHP unit1，P2Representing the CCHP plant electric power.
The cold-heat ratio is 1.2 COP.
Let load 1 be a commercial load, load 2 be an industrial load, and load 3 be a consumer load. The power factor of the load is 0.95, and the power factor of the wind power and the photovoltaic power is 0.8.
Setting e1 as a balance node, setting e3, e4 and e5 (namely load 1, load 2 and load 3) as PQ nodes, setting e2 and e6 (namely CCHP1 and CCHP2) as PV-PQ nodes, and listing the static power flow model of the power system expressed in the step two according to the parameters, wherein n is 6, G is 6, and G is 2ij、BijThe reciprocal of the resistance and reactance of each line/transformer in tables 1 and 2, i.e. the conductance and susceptance per unit value of the line and transformer, i.e. the equation F in step foure＝0。
Then according to the pipeline head and end nodes in the table 3The connection relation is obtained by using graph theory to obtain the correlation matrix of the cold/hot network, namely the correlation matrix A at the step ofuLower correlation matrix AdAnd loop matrix BfIf the cold/hot network system has no leakage, Q is 0, and if the pipes are in the same horizontal plane, Z is 0, H0*、SpConverting parameters of a nameplate of the pump into given values; t isaI.e. the local ambient temperature in which the coupling device is located, is also a given value, M x, ah*,Te*,Tn*,QJIs the state quantity of the cold/hot network to be solved, so the static power flow model of the cold/hot network expressed by the step one, namely the equation F in the step four of the formula can be listedh＝0。
The electric heating and cold coupling device in this embodiment has only CCHP1 and CCHP2, so that only formula 11 may be calculated, and formula 11 in step three, that is, formula P ═ F (Q), that is, formula F in step four, is obtained according to the above-mentioned formula of thermoelectric ratio and formula of cold-heat ratio of the CCHP unit eh0. Therefore, a static power flow model of the multi-energy complementary comprehensive energy coupling system can be obtained.
And solving according to the calculation flow of the step five. Wherein the step of "calculating S and E" in step (b) is based on the non-electric system state quantity X obtained by each iterationhThe value of M is calculated, and thus, M varies during the iteration process. Wherein, the power system load flow calculation is handed over to the existing power system simulation software calculation; generating a dynamic link library of a corresponding model according to customer self-definition by the load flow calculation of the cold/heat network system and the load flow calculation of the coupling equipment, calling a dynamic link library file through a user program interface of the power system simulation analysis software to realize joint calculation, wherein the calculation result is XhAnd XeThe final converged numerical solution of (1).
Fig. 8 shows the results obtained by respectively adopting the electric heating and cooling unified iterative algorithm and the electric heating and cooling different iterative algorithm when electric heating and cooling are coupled. For example, the optimal multiplier method is adopted for power system calculation, and the Newton-Raphson method is adopted for hot network and cold network calculation, and it can be seen from the figure that the hybrid solution algorithm adopting different iterative algorithms can realize faster convergence.
Fig. 9, 10 and 11 are calculated results of the temperatures of the nodes of the hot network, the cold network and the power grid according to the present embodiment.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and the present invention may be variously modified and changed. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. A static power flow analysis method for a multi-energy complementary comprehensive energy system is characterized by comprising the following steps: the method comprises the following steps:
firstly, performing network topology analysis on a non-electric system abstract diagram based on a diagram theory to construct a non-electric system power flow model;
the non-electrical system power flow model comprises the following steps:
Figure FDA0002541885830000011
wherein A is a correlation matrix, Au、AdRespectively an upper and a lower correlation matrix, BfIs a loop matrix; m is a flow column vector of a B-stage pipeline, Q is an inflow flow column vector of an N-stage node, Delta H is a differential pressure column vector of the B-stage pipeline, Z is a height difference column vector of a head-end node and a tail-end node of the B-stage pipeline, TeIs the column vector (DEG C) of the tail end temperature of the B-stage pipeline, TnIs an N-order node temperature column vector (DEG C), QJIs the N-th order node heat load column vector, TaIs a B-order ambient temperature array vector (DEG C), E is a B-order temperature attenuation coefficient diagonal matrix, S is a B-order pipeline resistance coefficient array vector, HpIs the pump head column vector, HvIs the column vector of the differential pressure on two sides of the valve;
step two, constructing a power flow model of the power system;
representing each coupling device by using a power output external characteristic equation, and constructing a coupling device operation external characteristic model for coupling between a non-electric system and an electric power system;
the external characteristic model of the coupling equipment for coupling the non-electric system and the electric power system is as follows:
Figure FDA0002541885830000012
wherein, PG*、QGRespectively as electric and thermal powers, P, of combined-supply unitpElectrical pump power, η pump efficiency, m fluid flow in the pump, HpIs pump head, Qhp*、Qeb*、QcRespectively the thermal powers of heat pump, electric boiler and refrigerating machine, Php*、Peb*、PcThe electric power of the heat pump, the electric boiler and the refrigerating machine is respectively set;
step four, establishing a non-electric system power flow model in the step one, a power system power flow model in the step two and a coupling device operation external characteristic model in the step three in a simultaneous manner, and constructing a static power flow model of the multi-energy complementary comprehensive energy system;
solving the static power flow model of the four-energy complementary comprehensive energy system by adopting a hybrid solving algorithm, wherein the hybrid solving algorithm is that a non-electric system power flow model and a power system power flow model are respectively solved by using different iterative algorithms;
the hybrid solution algorithm comprises the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix;
(2) initializing the state quantity X of the power system of the random distribution coupling equipment when the number of the initialization iterations k is equal to 0e (k)And a non-electrical system state quantity Xh (k)；
(3) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (4); otherwise, the calculation is finished;
(4) coupling device electric power P according to post-convergence coupling devicee (k)Operating an external characteristic model to the non-electric system state quantity X by utilizing the step three-coupling equipmenth (k)Corrected and recorded as Xh’(k)；
(5) According to corrected non-electric systemQuantity of state Xh’(k)Carrying out non-electric system load flow calculation; then judging whether the non-electric system load flow calculation is converged, if so, jumping to the step (6), otherwise, finishing the calculation;
(6) calculating convergence result X according to non-electric system load flowh’(k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’(k)(ii) a Then judging whether | Pe’(k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (3) is returned after k + 1.
2. The static power flow analysis method for the multi-energy complementary comprehensive energy system according to claim 1, characterized in that: in the first step, directed edges of a graph corresponding to a pipeline in a non-electric system are used, a connecting piece corresponds to the top point of the graph, each pipeline section defines the positive direction of flow, the topological structure of the non-electric system is described by using a matrix of the graph, and a valve is used as an attached attribute of the pipeline to be calculated.
3. The static power flow analysis method for the multi-energy complementary comprehensive energy system according to claim 1, characterized in that: a pump head column vector H in the non-electric system power flow modelpThe calculation formula of the constituent elements is as follows:
Figure FDA0002541885830000021
Figure FDA0002541885830000031
wherein h isiIs a coefficient, m is the pipe flow,
Figure FDA0002541885830000032
for each pump head on the pipeline, belonging to HpColumn vector constituent elements, n0Is the rated speed of the pump motor shaft, n is the actual speed, hi.n0Is the coefficient of the pump motor at the rated rotating speed;
the column vector H of the pressure difference on two sides of the valvevThe calculation formula of the constituent elements is as follows:
Figure FDA0002541885830000033
wherein
Figure FDA0002541885830000034
Is the pressure difference between two sides of a valve on a pipeline and belongs to HvColumn vector component elements, ξ is the reciprocal of the valve opening, d is the pipe diameter (m), ρ is the fluid working medium density (kg/m3), and m is the pipe flow.
4. The static power flow analysis method for the multi-energy complementary comprehensive energy system according to claim 1, characterized in that: the static power flow model of the multi-energy complementary comprehensive energy system is as follows:
Figure FDA0002541885830000035
wherein, Fe0 denotes a step two power system power flow model, FhStep one non-electrical system power flow model, F, is represented by 0ehAnd 0 represents an external characteristic model of the step three-coupling equipment, and F0 represents a static power flow model of the multi-energy complementary comprehensive energy system.
5. The static power flow analysis method for the multi-energy complementary comprehensive energy system according to claim 1, characterized in that: when the non-electric system comprises n energy forms, n is more than or equal to 2; the hybrid solution algorithm comprises the following steps:
(1) analyzing the topological relation of the multi-energy complementary comprehensive energy system to obtain an incidence matrix of each non-electric system;
(2) initializing the state quantity X of the power system of the random distribution coupling equipment when the number of the initialization iterations k is equal to 0e (k)And non-electrical system stateQuantity Xh (k)、Xc (k)；
(3) Carrying out power system load flow calculation, then judging whether the power system load flow calculation is converged, and if so, jumping to the step (4); otherwise, the calculation is finished;
(4) according to the electric power P of the coupling device after convergencee (k)Utilizing the step three coupling equipment to operate the external characteristic model to the ith energy form state quantity Xh (k)Corrected and recorded as Xh’(k)Wherein i is 1;
(5) according to the corrected state quantity X of the first energy formh’(k)Carrying out load flow calculation; then judging whether the load flow calculation is converged, if so, jumping to the step (6), otherwise, finishing the calculation;
(6) according to the ith energy form state quantity X after convergenceh’(k)And coupling device electric power Pe (k)Utilizing the step three coupling equipment to operate the external characteristic model to the (i + 1) th energy form state quantity Xc (k)Corrected and recorded as Xc’(k)；
(7) According to the corrected i +1 energy form state quantity Xc’(k)Carrying out load flow calculation; then judging whether the load flow calculation is converged, if so, jumping to the step (8), otherwise, finishing the calculation;
(8) repeating steps (6) and (7) until i ═ n-1;
(9) calculating convergence result X according to load flow of n energy formsh’(k)、Xc’(k)Modifying the electric power P of the coupling element of a coupling devicee (k)Is denoted by Pe’(k)(ii) a Then judging whether | Pe’(k)-Pe (k)I < or k > kmaxWherein k ismaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (3) is returned after k + 1.
6. The static power flow analysis method for the multi-energy complementary comprehensive energy system according to claim 5, characterized in that: the load flow calculation of each energy form of the hybrid solution algorithm non-electric system comprises the following steps:
(a) initializing the number of iterations t to 0, and initializing the non-electric system state quantity X(t)＝Xh (k)；
(b) According to the non-electric system state quantity X(t)Calculating a B-order temperature attenuation coefficient diagonal array E and a B-order pipeline resistance coefficient column vector S according to the parameter values, and converting the B-order temperature attenuation coefficient diagonal array E and the B-order pipeline resistance coefficient column vector S into fixed values;
let S be an element in the pipeline resistance characteristic coefficient S, that is, a resistance coefficient on a certain pipeline, and the calculation formula is as follows:
Figure FDA0002541885830000041
wherein L is the length (m) of the pipeline, D is the diameter (m) of the pipeline, and rho is the density (kg/m) of the fluid working medium in the pipeline3) G is the acceleration of gravity (kg. m/s)2) K is a correction coefficient, and f is a pipeline friction coefficient;
the calculation formula of the B-order temperature attenuation coefficient diagonal matrix E is as follows:
Figure FDA0002541885830000051
wherein λ isi，Li，cpiAnd miRespectively representing the thermal conductivity, the length of the pipeline, the specific heat capacity of fluid working medium in the pipeline and the flow rate of the pipeline of the unit length of the ith pipeline, wherein i is more than or equal to 1 and less than or equal to B;
(c) and (3) expressing the non-electric system power flow model in the step one by using a functional relation as follows:
F(X)＝0；
wherein, F is an error function, and a Jacobian matrix J of the system is defined as:
Figure FDA0002541885830000052
calculating a Jacobian matrix J;
(d) updating X(t+1)＝X(t)-J \ F, then determine if | X(t+1)-X(t)I < or t > tmaxWherein, tmaxTaking an empirical value; if yes, the calculation is finished, otherwise, the step (b) is returned after t + 1.
7. A multi-energy complementary integrated energy system static power flow analysis system using the static power flow analysis method according to any one of claims 1 to 6, characterized in that: the power flow calculation method comprises a power analysis module, a non-power analysis module and a coupling analysis module, wherein the non-power analysis module is used for realizing the power flow calculation of a power flow model of a non-electric system in the first step, the power analysis module is used for realizing the power flow calculation of a power flow model of a power system in the second step, and the coupling analysis module is used for realizing the calculation of an external characteristic model of the operation of coupling equipment between the non-electric system and the power system; and the power analysis module, the non-power analysis module and the coupling analysis module realize data interaction to solve the static power flow model of the multi-energy complementary comprehensive energy system in the fourth step and the fifth step.
8. The system according to claim 7, wherein the system further comprises: the power analysis module performs power module load flow calculation, electric power of the coupling equipment is transmitted into the coupling analysis module after calculation convergence, the coupling analysis module corrects the non-electric state quantity according to the electric power and transmits the non-electric state quantity to the non-power analysis module for non-electric load flow calculation, and the electric power is transmitted to the coupling analysis module to recalculate electric power of the coupling device and transmits the electric power to the power analysis module after convergence; and if the power error of the coupling device obtained by the two previous and subsequent calculations meets the precision requirement, stopping the calculation, otherwise, refreshing the electric power of the coupling device in the power grid data of the electric power analysis module, and continuing the calculation.
9. The system according to claim 7, wherein the system further comprises: the non-power analysis module comprises two base classes of pipelines and nodes, an equipment model class which depends on the two base classes is designed on the basis and is used for referring to the same class of equipment, then a subclass model instance class of the equipment model class is designed, actual equipment is referred, a subclass model instance set class of the model instance class is designed, and the set of each actual equipment model object is realized, so that the non-power analysis module is formed.
10. The system according to claim 7, wherein the system further comprises: compiling the static power flow calculation of the non-power analysis module and the coupling analysis module into a dynamic link library file independently, and calling the file through a user program interface of the existing power system simulation analysis software to realize joint calculation; the existing power system simulation analysis software is used as a power analysis module.
11. The system according to claim 7, wherein the system further comprises: existing power system simulation analysis software is used as a power analysis module to be independently compiled into an executable program, and the program is embedded into a static power flow calculation program of a non-power analysis system and a coupling analysis system to be executed to complete combined calculation.
12. The system for analyzing the static power flow of the multi-energy complementary integrated energy system according to claim 10 or 11, wherein: a user establishes a self-defined transfer function mathematical model of the equipment through a graphical interface, the system automatically generates a model file, a dynamic link library program analyzes the model file and is internally provided with an algorithm, and mutual transfer and cooperative calculation of data are realized through an interface with a main program of the system.
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