CN116667357A - Tidal current calculation method, device and equipment for three-phase four-wire system power distribution network - Google Patents

Tidal current calculation method, device and equipment for three-phase four-wire system power distribution network Download PDF

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CN116667357A
CN116667357A CN202310642563.XA CN202310642563A CN116667357A CN 116667357 A CN116667357 A CN 116667357A CN 202310642563 A CN202310642563 A CN 202310642563A CN 116667357 A CN116667357 A CN 116667357A
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current
node
phase
line
calculation
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李巍
白浩
徐敏
杨炜晨
要若天
刘通
阳浩
郭琦
叶升言
顾衍璋
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CSG Electric Power Research Institute
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CSG Electric Power Research Institute
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The application relates to a power flow calculation method, a device and equipment of a three-phase four-wire system power distribution network, wherein the method comprises the steps of obtaining electric quantity parameters in real time; calculating according to the electrical quantity parameters to obtain three-phase load current; calculating to obtain a first neutral line current of the end node according to a first current of three phases of the end node; according to the first current and the three-phase load current corresponding to each node, a forward superposition mode is adopted to calculate and obtain three-phase current; calculating to obtain a second neutral line current according to the first neutral line current and the three-phase load current; the voltage of the tail node is obtained by backward pushing and calculating according to the impedance data of the electrical quantity parameters, the voltage amplitude of the head node, the first current and the second neutral line current; and (3) re-acquiring the electric quantity parameters, carrying out iterative computation by adopting the forward push back power flow until the voltage difference value of the two adjacent end node voltages meets the convergence condition, correcting the node voltages obtained by the iterative computation to obtain voltage data of a power flow computation result, and improving the precision of the power flow computation result.

Description

Tidal current calculation method, device and equipment for three-phase four-wire system power distribution network
Technical Field
The application relates to the technical field of power flow analysis of power distribution networks, in particular to a power flow calculation method, device and equipment of a three-phase four-wire system power distribution network.
Background
In order to solve the serious environmental problems caused by the huge consumption of fossil energy, the construction of a clean and efficient novel energy system becomes the primary direction of the current development of the power system. The novel energy system is built, a large amount of clean energy sources such as photovoltaic energy, wind energy and the like are required to be accessed, and the utilization efficiency of the clean energy sources is improved.
With the continuous development of photovoltaic power generation technology, the technical difficulty of photovoltaic power generation is continuously overcome, the cost of photovoltaic power generation is also continuously reduced, and renewable energy power generation represented by photovoltaic power generation is one of the important directions of current energy utilization. However, a large number of accesses of the distributed photovoltaic power stations also bring some problems to the power distribution network, and the problems of voltage out-of-limit, power flow foldback and the like of the power distribution network are easy to occur due to the characteristics of randomness of photovoltaic output, mismatching of output and load time sequence and the like. The low-voltage power distribution network adopts a three-phase four-wire system circuit structure, so that the three-phase unbalance phenomenon is generated under the conditions of asymmetric access of three-phase loads and asymmetric parameters of the circuit, and the three-phase unbalance of the low-voltage power distribution network is further aggravated by large-scale single-phase grid connection of photovoltaic. In addition, in order to improve the photovoltaic digestion capability, the in-situ digestion of the photovoltaic output is realized, a plurality of power distribution networks at present adopt a flexible interconnection mode, two alternating current power networks are connected through an inverter, the photovoltaic output is transmitted through a direct current circuit, and the photovoltaic digestion rate is improved. The access of the converters further changes the flow direction of the power in the distribution network.
For the power distribution network in the balanced state, the transformer, the power line, the parallel capacitor, the load and the like in the default power distribution network are three-phase symmetrical, so that the power flow of the power distribution network can be calculated according to a single-phase line model. However, at present, the low-voltage power distribution network is actually a three-phase four-wire system circuit, the three-phase three-wire system circuit and the three-phase four-wire system circuit have essential differences in terms of load flow calculation modes and the like, the parameters of the low-voltage power distribution network circuit are asymmetric, a large amount of loads are single-phase access rather than three-phase access, the three-phase imbalance of the low-voltage power distribution network is further aggravated by large-scale photovoltaic single-phase grid connection, the three-phase imbalance can not be accurately reflected by adopting a three-phase three-wire system single-phase circuit model, and errors can exist when the circuit loss is calculated.
Disclosure of Invention
The embodiment of the application provides a method, a device and equipment for calculating the power flow of a three-phase four-wire system power distribution network, which are used for solving the technical problem that the error of a calculation result is large due to the unbalance of three phases of the three-phase four-wire system power distribution network in the existing power flow calculation mode of the power distribution network.
In order to achieve the above object, the embodiment of the present application provides the following technical solutions:
On the one hand, the utility model provides a three-phase four-wire system distribution network power flow calculation method, which comprises the following steps:
s1, acquiring m nodes of a line in a three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes in real time, wherein the electric quantity parameters comprise first current, voltage amplitude, impedance data, active power and reactive power; according to the electrical quantity parameters, three-phase load currents of the section of the circuit corresponding to each node are obtained through calculation;
s2, calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node;
s3, according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the first current of each node and the second neutral line current, the voltage of the last node is obtained through backward pushing calculation;
s4, acquiring m nodes of the line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes again, performing iterative computation by adopting forward-push back power flow in the steps S1 to S3 until the voltage difference value of the voltages of the two adjacent end nodes meets a convergence condition, and correcting the voltage of each node obtained by iterative computation to obtain voltage data of the power flow computation of the three-phase four-wire system power distribution network.
Preferably, the calculating according to the electrical quantity parameter to obtain the three-phase load current of the section line corresponding to each node includes:
calculating by adopting a three-phase load current formula according to the electrical quantity parameters to obtain three-phase load current of a section of line corresponding to each node;
wherein, the three-phase load current formula is:
wherein P is i The active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
Preferably, the load flow calculation method of the three-phase four-wire system distribution network comprises the following steps:
calculating by adopting a neutral current calculation formula according to the first current of the three phases of the end node to obtain the first neutral line current of the end node;
according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained;
calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
Wherein, the neutral current calculation formula is:
the first section line current calculation formula is as follows:
the formula of KCL law is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The current of a, b and c three phases flowing through the first-stage line is respectively +.>Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.> Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
Preferably, the load flow calculation method of the three-phase four-wire system distribution network comprises the following steps:
according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the three-phase load current of the section line corresponding to each node and the second neutral line current, a voltage calculation formula is adopted to carry out backward calculation, and the final node voltage is obtained;
the voltage calculation formula is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.>Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +. > Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->The terminal voltages of the three phases a, b, c and the neutral line n respectively,the voltage amplitudes of the three phases a, b and c and the n first nodes of the neutral line are respectively.
Preferably, correcting the voltage of each node obtained by iterative calculation to obtain voltage data of three-phase four-wire system distribution network tide calculation includes: correcting the voltage of each node obtained by iterative calculation by adopting a correction formula to obtain voltage data of three-phase four-wire system power distribution network tide calculation; the correction formula is:
in the method, in the process of the invention,the voltage amplitudes of the three phases a, b, c and the neutral line n at the ith node,and calculating three-phase voltage data for the three-phase four-wire system power distribution network power flow respectively.
Preferably, the convergence condition is:
in the method, in the process of the invention,and the voltage is the last node voltage calculated in the kth iteration in the tide calculation process, and epsilon is a difference threshold.
On the other hand, the utility model provides a three-phase four-wire system distribution network's trend calculation device, including first calculation module, second calculation module, third calculation module and fourth calculation module;
the first calculation module is used for acquiring m nodes of a line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes in real time, wherein the electric quantity parameters comprise first current, voltage amplitude, impedance data, active power and reactive power; according to the electrical quantity parameters, three-phase load currents of the section of the circuit corresponding to each node are obtained through calculation;
The second calculation module is used for calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node;
the third calculation module is used for performing backward pushing calculation according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the first current of each node and the second neutral line current to obtain the voltage of the last node;
and the fourth calculation module is used for re-acquiring m nodes of the circuit in the three-phase four-wire system distribution network and electric quantity parameters of the circuit corresponding to the nodes, performing iterative calculation by adopting the forward push back power flow of the first calculation module, the second calculation module and the third calculation module until the voltage difference value of the two adjacent terminal node voltages meets a convergence condition, and correcting the voltage of each node obtained by iterative calculation to obtain voltage data of the three-phase four-wire system distribution network power flow calculation.
Preferably, the second calculation module is further configured to calculate, according to a neutral current calculation formula, a first neutral line current of the end node by using a neutral current calculation formula according to the first current of the three phases of the end node; according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained; calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
wherein, the neutral current calculation formula is:
the first section line current calculation formula is as follows:
the formula of KCL law is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The current of a, b and c three phases flowing through the first-stage line is respectively +.>Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.> Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
Preferably, the first calculation module is further configured to calculate, according to the electrical quantity parameter, a three-phase load current formula to obtain a three-phase load current of a section of the line corresponding to each node;
The third calculation module is further used for performing backward calculation according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the three-phase load current of the section line corresponding to each node and the second neutral line current by adopting a voltage calculation formula to obtain the voltage of the last node;
wherein, the three-phase load current formula is:
the voltage calculation formula is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.>Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +.> Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->The terminal voltages of the three phases a, b, c and the neutral line n respectively,the voltage amplitude values of the three phases a, b and c and the n head nodes of the neutral line are respectively; p (P) i The active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
In yet another aspect, a terminal device is provided that includes a processor and a memory;
The memory is used for storing program codes and transmitting the program codes to the processor;
and the processor is used for executing the power flow calculation method of the three-phase four-wire system power distribution network according to the instructions in the program codes.
From the above technical solutions, the embodiment of the present application has the following advantages: the method comprises the steps of S1, acquiring m nodes of a circuit in the three-phase four-wire system power distribution network and electric quantity parameters of a circuit of a section corresponding to the nodes in real time; according to the electrical quantity parameter calculation, three-phase load current of the section line corresponding to each node is obtained; s2, calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node; s3, according to impedance data of the electrical quantity parameters, voltage amplitude of the first node, first current of each node and second neutral line current of each node, pushing back and calculating to obtain final node voltage; s4, acquiring m nodes of the line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes again, performing iterative computation by adopting forward-push back power flow in the steps S1 to S3 until the voltage difference value of the voltages of two adjacent end nodes is obtained to meet a convergence condition, and correcting the voltage of each node obtained by iterative computation to obtain voltage data of the three-phase four-wire system power distribution network power flow computation. According to the power flow calculation method of the three-phase four-wire system power distribution network, the power flow calculation is carried out on the three-phase four-wire system power distribution network by adopting a forward push back substitution power flow calculation mode through obtaining the electrical quantity parameters, so that the calculated result reduces errors of a power flow theory and an actual power flow theory of the three-phase four-wire system power distribution network, and the precision of the power flow calculation result is improved; according to the power flow calculation method of the three-phase four-wire system power distribution network, neutral line parameters are calculated, power flow data of all nodes and branches in the three-phase asymmetric power distribution network can be calculated accurately, and the power flow calculation accuracy is further improved. The technical problem that the calculation result error is large due to the fact that the three phases of a three-phase four-wire system power distribution network are unbalanced in the current power distribution network power flow calculation mode is solved.
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In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
Fig. 1 is a flow chart of steps of a method for calculating a power flow of a three-phase four-wire system power distribution network according to an embodiment of the present application;
fig. 2 is a schematic topology diagram of a three-phase four-wire system power distribution network in a power flow calculation method of the three-phase four-wire system power distribution network according to an embodiment of the present application;
fig. 3 is a frame flow chart of a power flow calculation device of a three-phase four-wire system power distribution network according to an embodiment of the application.
Detailed Description
In order to make the objects, features and advantages of the present application more comprehensible, the technical solutions in the embodiments of the present application are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the description of embodiments of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless explicitly defined otherwise.
In the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and include, for example, either permanently connected, removably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.
The embodiment of the application provides a method, a device and equipment for calculating the power flow of a three-phase four-wire system power distribution network, which are used for solving the technical problem that the error of a calculation result is large due to the unbalance of three phases of the three-phase four-wire system power distribution network in the existing power flow calculation mode of the power distribution network.
Embodiment one:
fig. 1 is a flow chart of steps of a power flow calculation method of a three-phase four-wire system power distribution network according to an embodiment of the present application, and fig. 2 is a topology schematic diagram of the three-phase four-wire system power distribution network in the power flow calculation method of the three-phase four-wire system power distribution network according to the embodiment of the present application.
As shown in fig. 1 and fig. 2, the embodiment of the application provides a power flow calculation method of a three-phase four-wire system power distribution network, which includes the following steps:
s1, acquiring m nodes of a line in a three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes in real time, wherein the electric quantity parameters comprise first current, voltage amplitude, impedance data, active power and reactive power; and calculating according to the electrical quantity parameters to obtain the three-phase load current of the section line corresponding to each node.
In step S1, firstly, electrical quantity parameters of a line in the three-phase four-wire system power distribution network are obtained, and secondly, three-phase load currents of line segments where each node is located are calculated according to the obtained electrical quantity parameters, so that data is provided for follow-up forward push back generation tide calculation.
S2, calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; and calculating according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining the second neutral line current of each node except the last node.
In step S2, first, a first neutral line current is obtained according to the first current of the terminal three phases obtained in step S1; secondly, according to the step S1, obtaining a first current of each node and calculating a three-phase load current of a section line where each node is positioned, and obtaining a three-phase current of a first section line; and finally, calculating the current of each node except the tail node on the neutral line, namely the second neutral line current.
S3, according to impedance data of the electrical quantity parameters, voltage amplitude of the first node, first current of each node and second neutral line current of each node, the final node voltage is obtained through backward pushing calculation.
In step S3, the final node voltage of the line in the three-phase four-wire system power distribution network is obtained by adopting a backward pushing calculation according to the impedance data obtained in step S1, the voltage amplitude of the first node, the first current of each node and the second neutral line current calculated in step S2.
S4, acquiring m nodes of the line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes again, performing iterative computation by adopting forward-push back power flow in the steps S1 to S3 until the voltage difference value of the voltages of two adjacent end nodes is obtained to meet a convergence condition, and correcting the voltage of each node obtained by iterative computation to obtain voltage data of the three-phase four-wire system power distribution network power flow computation.
In step S4, the iterative computation is performed on the m nodes of the line in the three-phase four-wire system power distribution network and the electrical quantity parameters of the line corresponding to the nodes by adopting the forward push back power flow in the computation mode of steps S1 to S3 until the obtained voltage difference value of the voltages of two adjacent end nodes meets the convergence condition. And secondly, correcting the voltage of each node meeting the convergence condition to obtain voltage data of the three-phase four-wire system power distribution network power flow calculation. In the embodiment, the power flow calculation method of the three-phase four-wire system power distribution network comprehensively considers the existence of neutral wires, and can calculate the power flow data of each node and branch in the three-phase asymmetric power distribution network more accurately.
The application provides a power flow calculation method of a three-phase four-wire system power distribution network, which comprises the following steps of S1, acquiring m nodes of a circuit in the three-phase four-wire system power distribution network and electric quantity parameters of a circuit of a section corresponding to the nodes in real time; according to the electrical quantity parameter calculation, three-phase load current of the section line corresponding to each node is obtained; s2, calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node; s3, according to impedance data of the electrical quantity parameters, voltage amplitude of the first node, first current of each node and second neutral line current of each node, pushing back and calculating to obtain final node voltage; s4, acquiring m nodes of the line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes again, performing iterative computation by adopting forward-push back power flow in the steps S1 to S3 until the voltage difference value of the voltages of two adjacent end nodes is obtained to meet a convergence condition, and correcting the voltage of each node obtained by iterative computation to obtain voltage data of the three-phase four-wire system power distribution network power flow computation. According to the power flow calculation method of the three-phase four-wire system power distribution network, the power flow calculation is carried out on the three-phase four-wire system power distribution network by adopting a forward push back substitution power flow calculation mode through obtaining the electrical quantity parameters, so that the calculated result reduces errors of a power flow theory and an actual power flow theory of the three-phase four-wire system power distribution network, and the precision of the power flow calculation result is improved; according to the power flow calculation method of the three-phase four-wire system power distribution network, neutral line parameters are calculated, power flow data of all nodes and branches in the three-phase asymmetric power distribution network can be calculated accurately, and the power flow calculation accuracy is further improved. The technical problem that the calculation result error is large due to the fact that the three phases of a three-phase four-wire system power distribution network are unbalanced in the current power distribution network power flow calculation mode is solved.
In one embodiment of the present application, according to each node and the electrical quantity parameter of the section line where the node is located, the obtaining the three-phase load current of the section line where the node is located includes:
according to the electrical quantity parameters, a three-phase load current formula is adopted to calculate, and three-phase load currents of the section of the circuit corresponding to each node are obtained;
wherein, three-phase load current formula is:
wherein P is i The active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
In one embodiment of the present application, the method for calculating the power flow of the three-phase four-wire system power distribution network includes:
calculating by adopting a neutral current calculation formula according to the first current of the three phases of the end node to obtain the first neutral line current of the end node;
according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained;
Calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
wherein, the neutral current calculation formula is:
the first section line current calculation formula is:
the formula of KCL law is:
in the method, in the process of the application,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The three phases a, b and c respectively flow through the first-section lineFlow (I)>Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.> Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
In one embodiment of the present application, the method for calculating the power flow of the three-phase four-wire system power distribution network includes: according to impedance data of the electrical quantity parameters, voltage amplitude of the first node, three-phase load current of a section line where each node corresponds to and second neutral line current, adopting a voltage calculation formula to carry out backward calculation to obtain final node voltage;
the voltage calculation formula is:
in the method, in the process of the application,respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +. >Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +.> Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->The terminal voltages of the three phases a, b, c and the neutral line n respectively,the voltage amplitudes of the three phases a, b and c and the n first nodes of the neutral line are respectively.
The method for calculating the power flow of the three-phase four-wire system power distribution network sequentially returns the current to the tail end of the line through a voltage calculation formula, so that the terminal node voltage of the three-phase and neutral wires can be calculated. The power flow calculation method of the three-phase four-wire system power distribution network has completely executed one-time forward push back power flow calculation through the steps S1 to S3.
In one embodiment of the application, the parameters of the electrical quantities of m nodes of the line in the three-phase four-wire system power distribution network and the line corresponding to the nodes are obtained again, and then iterative calculation is performed according to the content of the steps S1 to S3 until the voltage difference value of the voltages of two adjacent end nodes is obtained to meet the convergence condition, and then the power flow calculation of the first alternating current line or the second alternating current line of the three-phase four-wire system power distribution network is finished.
Wherein, the convergence condition is:
in the method, in the process of the application,for last node voltage calculated in the kth iteration in the tide calculation process, epsilon is a difference threshold value, and the difference threshold valueThe difference threshold value may be set according to the requirement, and is not limited herein.
It should be noted that, the last node voltage of the kth iterative computation includes four voltages of a, b, c three phases and a neutral line, and the convergence condition means that the iterative computation is completed only when the four voltages all meet the condition.
In one embodiment of the present application, correcting the voltage of each node obtained by iterative calculation to obtain voltage data of three-phase four-wire system power distribution network tide calculation includes: correcting the voltage of each node obtained by iterative calculation by adopting a correction formula to obtain voltage data of three-phase four-wire system power distribution network tide calculation; the correction formula is:
in the method, in the process of the application,the voltage amplitudes of the three phases a, b, c and the neutral line n at the ith node,and calculating three-phase voltage data for the three-phase four-wire system power distribution network power flow respectively.
Embodiment two:
fig. 3 is a frame flow chart of a power flow calculation device of a three-phase four-wire system power distribution network according to an embodiment of the application.
As shown in fig. 3, an embodiment of the present application provides a power flow calculation device for a three-phase four-wire system power distribution network, including a first calculation module 10, a second calculation module 20, a third calculation module 30, and a fourth calculation module 40;
The first calculation module 10 is configured to obtain, in real time, electrical quantity parameters of m nodes of a line in the three-phase four-wire system power distribution network and a line corresponding to the nodes, where the electrical quantity parameters include a first current, a voltage amplitude, impedance data, active power and reactive power; according to the electrical quantity parameter calculation, three-phase load current of the section line corresponding to each node is obtained;
the second calculation module 20 is configured to calculate, according to the first current of the three phases of the end node, a first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node;
the third calculation module 30 is configured to calculate, by pushing backward, a final node voltage according to impedance data of the electrical quantity parameter, a voltage amplitude of the first node, a first current of each node, and a second neutral line current;
and the fourth calculation module 40 is configured to re-acquire the m nodes of the line in the three-phase four-wire system power distribution network and the electrical quantity parameters of the line corresponding to the nodes, perform iterative calculation by adopting the first calculation module, the second calculation module and the third calculation module to replace the power flow in the forward pushing manner until the voltage difference value of the two adjacent end node voltages meets the convergence condition, and correct the voltage of each node obtained by iterative calculation to obtain the voltage data of the power flow calculation of the three-phase four-wire system power distribution network.
In the embodiment of the present application, the second calculation module 20 is further configured to calculate, according to the first current of the three phases of the end node, a neutral current calculation formula to obtain a first neutral current of the end node; according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained; calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
wherein, the neutral current calculation formula is:
the first section line current calculation formula is:
the formula of KCL law is:
in the method, in the process of the application,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The current of a, b and c three phases flowing through the first-stage line is respectively +.>Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.> Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
In the embodiment of the present application, the first calculation module 10 is further configured to calculate, according to the electrical quantity parameter, a three-phase load current formula to obtain a three-phase load current of a section of the line corresponding to each node;
The third calculation module 30 is further configured to perform backward calculation according to a voltage calculation formula according to impedance data of the electrical quantity parameter, a voltage amplitude of the first node, a three-phase load current of a section of the line where each node corresponds to, and a second neutral line current, so as to obtain a final node voltage;
wherein, three-phase load current formula is:
the voltage calculation formula is:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.>Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +.> Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->The terminal voltages of the three phases a, b, c and the neutral line n respectively,the voltage amplitude values of the three phases a, b and c and the n head nodes of the neutral line are respectively;P i the active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
It should be noted that, the content of the module in the tidal current calculation device of the three-phase four-wire system power distribution network corresponds to the content of the steps in the method of the embodiment, the content of the steps in the method of the embodiment has been described in the embodiment one, and the description of the content of the module in the device of the embodiment two is not repeated in this embodiment.
Embodiment III:
the embodiment of the application provides terminal equipment, which comprises a processor and a memory;
a memory for storing program code and transmitting the program code to the processor;
and the processor is used for executing the power flow calculation method of the three-phase four-wire system power distribution network according to the instructions in the program codes.
It should be noted that the processor is configured to execute the steps in the embodiment of the method for calculating the power flow of the three-phase four-wire system power distribution network according to the instructions in the program code. In the alternative, the processor, when executing the computer program, performs the functions of the modules/units in the system/apparatus embodiments described above.
For example, a computer program may be split into one or more modules/units, which are stored in a memory and executed by a processor to perform the present application. One or more of the modules/units may be a series of computer program instruction segments capable of performing specific functions for describing the execution of the computer program in the terminal device.
The terminal device may be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server, etc. The terminal device may include, but is not limited to, a processor, a memory. It will be appreciated by those skilled in the art that the terminal device is not limited and may include more or less components than those illustrated, or may be combined with certain components, or different components, e.g., the terminal device may also include input and output devices, network access devices, buses, etc.
The processor may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may be an internal storage unit of the terminal device, such as a hard disk or a memory of the terminal device. The memory may also be an external storage device of the terminal device, such as a plug-in hard disk provided on the terminal device, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), or the like. Further, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used for storing computer programs and other programs and data required by the terminal device. The memory may also be used to temporarily store data that has been output or is to be output.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. The power flow calculation method of the three-phase four-wire system power distribution network is characterized by comprising the following steps of:
s1, acquiring m nodes of a line in a three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes in real time, wherein the electric quantity parameters comprise first current, voltage amplitude, impedance data, active power and reactive power; according to the electrical quantity parameters, three-phase load currents of the section of the circuit corresponding to each node are obtained through calculation;
s2, calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node;
S3, according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the first current of each node and the second neutral line current, the voltage of the last node is obtained through backward pushing calculation;
s4, acquiring m nodes of the line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes again, performing iterative computation by adopting forward-push back power flow in the steps S1 to S3 until the voltage difference value of the voltages of the two adjacent end nodes meets a convergence condition, and correcting the voltage of each node obtained by iterative computation to obtain voltage data of the power flow computation of the three-phase four-wire system power distribution network.
2. The method for calculating the power flow of the three-phase four-wire system power distribution network according to claim 1, wherein calculating the three-phase load current of the section line corresponding to each node according to the electrical quantity parameter comprises:
calculating by adopting a three-phase load current formula according to the electrical quantity parameters to obtain three-phase load current of a section of line corresponding to each node;
wherein, the three-phase load current formula is:
wherein P is i The active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
3. The power flow calculation method of a three-phase four-wire system power distribution network according to claim 1, comprising:
calculating by adopting a neutral current calculation formula according to the first current of the three phases of the end node to obtain the first neutral line current of the end node;
according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained;
calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
wherein, the neutral current calculation formula is:
the first section line current calculation formula is as follows:
the formula of KCL law is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The current of a, b and c three phases flowing through the first-stage line is respectively +.>Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +. > Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
4. The power flow calculation method of a three-phase four-wire system power distribution network according to claim 1, comprising:
according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the three-phase load current of the section line corresponding to each node and the second neutral line current, a voltage calculation formula is adopted to carry out backward calculation, and the final node voltage is obtained;
the voltage calculation formula is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.>Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +.> Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->Terminal voltages of three phases a, b, c and neutral n, respectively，The voltage amplitudes of the three phases a, b and c and the n first nodes of the neutral line are respectively.
5. The method for calculating the power flow of the three-phase four-wire system power distribution network according to claim 1, wherein correcting the voltage of each node obtained by the iterative calculation to obtain the voltage data of the three-phase four-wire system power distribution network power flow calculation comprises: correcting the voltage of each node obtained by iterative calculation by adopting a correction formula to obtain voltage data of three-phase four-wire system power distribution network tide calculation; the correction formula is:
In the method, in the process of the invention,the voltage amplitudes of the three phases a, b, c and the neutral line n at the ith node,and calculating three-phase voltage data for the three-phase four-wire system power distribution network power flow respectively.
6. The method for calculating the power flow of the three-phase four-wire system power distribution network according to claim 1, wherein the convergence condition is:
in the method, in the process of the invention,and the voltage is the last node voltage calculated in the kth iteration in the tide calculation process, and epsilon is a difference threshold.
7. The utility model provides a three-phase four-wire system distribution network's trend calculation device which characterized in that includes first calculation module, second calculation module, third calculation module and fourth calculation module;
the first calculation module is used for acquiring m nodes of a line in the three-phase four-wire system power distribution network and electric quantity parameters of the line corresponding to the nodes in real time, wherein the electric quantity parameters comprise first current, voltage amplitude, impedance data, active power and reactive power; according to the electrical quantity parameters, three-phase load currents of the section of the circuit corresponding to each node are obtained through calculation;
the second calculation module is used for calculating according to the first current of the three phases of the end node to obtain the first neutral line current of the end node; according to the first current corresponding to each node and the three-phase load current of the line of the section where the first current is positioned, adopting a forward superposition mode to calculate to obtain the three-phase current of the first section of line; according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, calculating to obtain a second neutral line current of each node except the last node;
The third calculation module is used for performing backward pushing calculation according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the first current of each node and the second neutral line current to obtain the voltage of the last node;
and the fourth calculation module is used for re-acquiring m nodes of the circuit in the three-phase four-wire system distribution network and electric quantity parameters of the circuit corresponding to the nodes, performing iterative calculation by adopting the forward push back power flow of the first calculation module, the second calculation module and the third calculation module until the voltage difference value of the two adjacent terminal node voltages meets a convergence condition, and correcting the voltage of each node obtained by iterative calculation to obtain voltage data of the three-phase four-wire system distribution network power flow calculation.
8. The power flow calculation device of the three-phase four-wire system power distribution network according to claim 7, wherein the second calculation module is further configured to calculate, according to a first current of the three phases of the end node, by using a neutral current calculation formula, to obtain a first neutral current of the end node; according to the first current corresponding to each node and the three-phase load current of the section line where the first current is positioned, a front superposition mode first section line current calculation formula is adopted to calculate, and the three-phase current of the first section line is obtained; calculating by adopting a KCL law formula according to the first neutral line current and the three-phase load current of the section line where each node corresponds to, and obtaining a second neutral line current of each node except the last node;
Wherein, the neutral current calculation formula is:
the first section line current calculation formula is as follows:
the formula of KCL law is as follows:
in the method, in the process of the invention,respectively, a, b and c three phases are respectively first current after flowing through the m-th section line, +.>First neutral current for the end node, +.>The current of a, b and c three phases flowing through the first-stage line is respectively +.>A, b respectively,c three-phase first current after flowing through the ith section line, "> Load current of a, b and c three phases flowing through the ith section of line respectively, +.>A second neutral current that is the neutral of the ith node.
9. The power flow calculation device of the three-phase four-wire system power distribution network according to claim 7, wherein the first calculation module is further configured to calculate, according to the electrical quantity parameter, a three-phase load current formula to obtain a three-phase load current of a section of a line corresponding to each node;
the third calculation module is further used for performing backward calculation according to the impedance data of the electrical quantity parameters, the voltage amplitude of the first node, the three-phase load current of the section line corresponding to each node and the second neutral line current by adopting a voltage calculation formula to obtain the voltage of the last node;
wherein, the three-phase load current formula is:
The voltage calculation formula is as follows:
in the middle of，Respectively, a, b and c three phases are respectively first current after flowing through the ith section line, +.>Second neutral current, which is the neutral line of the ith node,/>Impedance data on the i-th section of the three phases a, b and c respectively, < >>Impedance data for neutral line of ith node, < +.> Voltage drop at the ith node for the three phases a, b, c and neutral line n, respectively,/->The terminal voltages of the three phases a, b, c and the neutral line n respectively,the voltage amplitude values of the three phases a, b and c and the n head nodes of the neutral line are respectively; p (P) i The active power input to the section line corresponding to the ith node, qi is the reactive power input to the section line corresponding to the ith node, U i For the voltage amplitude of the ith node, I load，i And a, b and c are respectively three phases a, b and c of a three-phase four-wire system for the load current of the line of the corresponding section of the ith node.
10. A terminal device comprising a processor and a memory;
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the power flow calculation method of the three-phase four-wire system power distribution network according to any one of claims 1 to 6 according to the instructions in the program code.
CN202310642563.XA 2023-05-31 2023-05-31 Tidal current calculation method, device and equipment for three-phase four-wire system power distribution network Pending CN116667357A (en)

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