76 results about "Network equation" patented technology

The present invention relates to the field of the electric power system electric power transmission line relay protection, especially to a technique of the single-phase self-adapting reclosing with a parallel reactor electric power transmission line, and the invention discloses a method for judging the permanent fault of the electric power transmission line with a parallel reactor. The method adopts the parameter recognizing principal and constructs an identification equation which uses the circular parallel reactor and neutral point small reactor a parameter to be determined basing on the network equation when the instantaneous fault has disappeared. The solving to the inductor parameter is realized by the sound phase voltage, sound phase current, parallel reactor current and neutral point small reactor at this side. According to the least square parameter estimate redundant algorithm the inductor parameter is solved, and the instantaneous fault and permanent fault are discriminated using the comparison between the solved inductor parameter and the actual inductor parameter.

The invention discloses an adaptive real-time dynamic mathematic modeling method for a direct-current traction power supply system in urban railway traffic. The method comprises the steps of: (1) inputting a parameter file at the t moment; (2) setting serial numbers of nodes at two ends of a traction substation and nodes at two ends of a locomotive to be continuous, and sorting the nodes at the two ends of the traction substation; judging whether the position of each locomotive at the t moment coincides with the position of the traction substation, and sorting the nodes at the two ends of the locomotive; arranging the serial numbers of the nodes from small to big according to position coordinates, and storing the serial numbers to arrays; (3) based on a node admittance network equation modeling principle, generating a node admittance network equation at the t moment by stored four node arrays and input parameters; (4) for the next (t+delta t) moment, reading the parameter file at the (t+delta t) moment to regenerate a dynamic mathematic model, wherein the steps are the same as the above steps; and repeating the steps continuously to finish real-time dynamic mathematic modeling. The method has the advantages that the true condition is better met, the self-adaptability is high, the calculation is simple and quick, and the like.

The present invention belongs to the power transmission and distribution technical field and relates to a multi-infeed direct-current transmission receiving end alternating-current system equivalent evaluation method. The method includes the following steps that: according to the network topological structure of a multi-infeed direct-current system, one of LCC-HVDC (line commutated converter based high voltage direct current) subsystems is selected as an equivalent subsystem; operating impedance related to the operating status of the LCC-HVDC subsystem is defined, and the operating impedance of each LCC-HVDC subsystem is solved on the basis of the definition of the operating impedance; on the basis of the operating impedance of each LCC-HVDC subsystem, the node network equation of the multi-infeed direct-current system is listed according to the obtained operating impedance and the network topological structure of the multi-infeed direct-current system; the equivalent impedance Zeq of the alternating-current bus-bar of the LCC-HVDC equivalent subsystem is solved according to the node network equation; and the equivalent effective short-circuit ratio (SCRLCC) of the multi-infeed direct-current receiving end alternating-current system can be obtained through calculation according to the equivalent impedance Zeq. With the evaluation method provided by the invention adopted, the strength of the multi-infeed direct-current receiving end alternating-current system can be effectively evaluated, and theoretical guidance can be provided for the improvement of the operating characteristics of the multi-infeed direct-current system.

The invention discloses a transient computing network equivalence-based electromagnetic transient simulation newly added model development method. The method comprises the following steps: S10, converting a newly added model circuit into an electromagnetic transient computing circuit model; S20, writing a corresponding transient computing network equation according to an equivalent circuit connection type of the electromagnetic transient computing circuit model; S30, performing Norton equivalence computation on the transient computing network equation to obtain parameters of each port of an equivalent circuit; S40, performing simultaneous solution on the parameters of each port and a main network to obtain a network solution of each time step. According to the method, the Norton equivalence is performed on the circuit which is subjected to the electromagnetic transient equivalence, so that the current value of each port and equivalent port conductance value are quickly obtained; a newly added model equivalent circuit is obtained by a programming method; a tedious equivalent circuit derivation process when a model is newly added is avoided through simultaneous computing of an interface and the main network.

The invention relates to a calculation method and system for a junction temperature of an IGBT module. The calculation method comprises the steps of acquiring an initial junction temperature of the IGBT module; calculating the loss of the IGBT module; establishing a heat network equation for heat transfer of the IGBT module according to a heat transfer relation between the IGBT module and a cooling system, and substituting the loss of the IGBT module into the established heat network equation to calculate temperature rise of the IGBT module; and adding the temperature rise of the IGBT module and the initial junction temperature of the corresponding IGBT module to obtain the junction temperature of the IGBT module. By means of the established heat network equation, the influence of the cooling system on the junction temperature of the IGBT module is fully considered, so that a result of junction temperature estimation is more accurate. The problem that existing junction temperature prediction is incomprehensive and inaccurate due to the fact that the cooling system is not considered is solved.

The invention discloses a fractional order cell neural network adaptive synchronization control and circuit design method. A fractional differential algorithm is selected, and the definition of a cell neural network equation is combined, thereby constructing a three-dimensional cell neural network system. The method comprises the steps: designing a drive-response system with a known drive system nonlinear parameter and an unknown response system nonlinear parameter based on the above system, constructing a new adaptive synchronizing controller and a parameter adaptive adjustment rate, and achieving the synchronization of the drive and response systems in numerical simulation; designing the circuit diagrams of the drive and response systems of the fractional order cell neural network, and achieving the circuit simulation of the controller and the adaptive adjustment rate. A simulation result indicates that the circuit simulation and the numerical simulation have the similar synchronous phase diagram, and the method verifies the accuracy of system theoretical analysis and the actual physical realizability. Therefore, the method is practical in the field of engineering.

The present invention provides a photovoltaic power station grid-connected fault model and analysis method of neutral point grounding through resistance. Based on an inversion power supply fault equivalence model with low-voltage crossing control strategy, a photovoltaic power station grid-connected system comprising neutral point grounding through resistance is subjected to modeling, and fault calculation models are respectively established aiming at the features of the system line of the grid-connected system and a collection line in a station. Each sequence network equation of the line fault calculation model and corresponding fault boundary conditions are combined to obtain a fault network multi-web nonlinear equation group, and the Newton-Ralfsnn's method is employed to construct an iteration correction equation to obtain a convergence solution so as to realize fault analysis. The grid-connected photovoltaic state employs a mode of the neutral point grounding through little resistance to solve the problem of fault modeling of the system, especially provide the possibility for the completion analysis of line faults through establishing of the collection line fault calculation model in the station, fully consider the influence of the neutral point grounding through resistance on the system zero sequence network and provide basis for a following protection design.

The invention relates to a natural gas path modeling method for operation control of a comprehensive energy system, and belongs to the technical field of operation control of the comprehensive energysystem. The method comprises the following steps: establishing a partial differential equation between flow and pressure in a natural gas pipeline based on a mass conservation and momentum conservation equation in the natural gas pipeline, a natural gas state equation and a flow equation; mapping the gas circuit to a frequency domain by using Fourier transform, and obtaining a lumped parameter model through two-port equivalents; a natural gas supercharger equation is combined, and a natural gas path general branch model is established; defining a node-branch incidence matrix and a node-outflowbranch incidence matrix, and establishing a topological constraint equation of a natural gas path; and establishing a natural gas path equation in combination with the natural gas path general branchmodel and the topological constraint equation of the natural gas path. The method has high unity with a network matrix and a network equation of a power network in mathematical form, thereby laying afoundation for unified analysis of gas and electricity heterogeneous energy flows.

The embodiment of the invention discloses a modelingsimulation method and device for a double half bridge sub-moduleMMC. According to the method, equivalent processing is conducted on each device of adoublehalf bridge sub-module to respectively obtain internal nodes and external nodes of an adjoint circuitof the doublehalf bridge sub-module, branches and the nodes of theadjoint circuit are numbered to obtain a cut set network equation of the adjoint circuit, the Norton equivalent model of the doublehalf bridge sub-module is solved according to a fast nesting solution algorithm, the Thevenin equivalent model of the doublehalf bridge sub-module is obtained according to a transformation method of Norton's theorem and Thevenin's theorem, equivalence is conducted on each sub-module of the double half bridge sub-moduleMMC by simulation circuit network of the doublehalf bridge sub-module MMC, simulation is conducted bymeans of electromagnetic transient simulatiadopting the Thevenin equivalent model of the doublehalf bridge sub-module to obtain a on software to update capacitor voltage of the double half bridge sub-module, and the technical problem of modeling of the double half bridge sub-moduleMMC is solved.

The invention provides a trajectory eigenvalue-based system transient stability judgment and disturbance type selection method. A state equation in an unsteady state condition, and a linear processing method for a generator, a governor, an excitation system, a network equation and load at a non-equilibrium point are studied. A higher-order linearization model for the system is built, continuous solution of the eigenvalue in the unsteady state condition is realized, a trajectory eigenvalue curve is obtained, and the trajectory eigenvalue curve characteristics are analyzed. through studying system dynamic information in the trajectory eigenvalue under load disturbance and three-phase short circuit fault, a limitation whether the real part of the eigenvalue is larger than zero does not exist, a potential law is explored, a mapping relationship among the system transient stability, a disturbance type and the trajectory eigenvalue is built, and thus, quick and accurate system transient stability judgment and disturbance type selection can be realized. Through example analysis on WSCC 3-machine 9-point, the conclusion obtained by the method of the invention is consistent with a relative power angle curve of the generator, and feasibility of the method is verified.

The invention discloses a short circuit current acquisition method for an electric power system including an impedance matching balance traction transformer. The short circuit current acquisition method comprises the following steps: finding a node admittance matrix under the symmetric component of the electric power system before the fault; obtaining a node admittance matrix under the symmetric component of the electric power system after the fault by modifying elements related to fault points in the node admittance matrix according to the short circuit position and the type; obtaining a node injection current column vector under the symmetric component of the electric power system after the fault according to a node injection current column vector under the symmetric component of the electric power system before the fault; obtaining the voltage of each node after the fault according to a system network equation after the fault; and obtaining each branch circuit after the fault according to each node voltage and each branch admittance obtained. The method is based on a symmetric component method and the node admittance matrix, thereby solving the technical problems that the multiple short circuit fault analysis cannot be conducted on an asymmetrical electric power system connected with the impedance matching balance traction transformer by the existing method. The method provided by the invention is conveniently integrated to the existing short circuit current acquisition software.

The invention provides an adaptive control mode switching-based UPFC alternating iteration power flow calculation method, which comprises the steps of: setting a head-end control power value of a series module of a UPFC, voltage phasor initial values of a head-end node i and a tail-end node j of the series module, the voltage phasor initial value of a node of a parallel module and an initial control mode of the series module; solving a UPFC module and an AC network equation; judging whether a power flow exit condition is met or not, and if so, exiting; judging whether to switch the control mode of the series module of the UPFC or not; updating voltage phasors of the head-end node and the tail-end node of the series module of the UPFC, the voltage phasor of the node of the parallel module and the control mode of the series module; and commanding k=k+1 and solving the network equation of the UPFC again. By the method provided by the invention, the problem of power flow calculation of a power system comprising the UPFC is solved; active power and reactive power of the UPFC on line power can be achieved; the control mode of the UPFC is adaptively adjusted; and the alternating iteration convergence is improved while the control precision of the UPFC is ensured.

The invention discloses a multi-network steady-state energy flow analysis method and device for an electricity-gas comprehensive energy system. The multi-network steady-state energy flow analysis method comprises the following steps: respectively carrying out topology analysis on an electrical network and a natural gas network in a to-be-analyzed electricity-gas comprehensive energy network, and determining an electrical network equation and a corresponding electrical system variable, a natural gas network equation and a corresponding natural gas system variable, an electricity-gas coupling element equation and a corresponding additional variable; and solving a nonlinear algebraic equation set comprising a power network equation, a natural gas network equation and a coupling element equation to obtain the value of the electrical system variable, the value of the natural gas system variable and the value of the additional variable, wherein the value of the electrical system variable, the value of the natural gas system variable and the value of the additional variable form a steady-state energy flow of the to-be-analyzed electricity-gas comprehensive energy network. The multi-network steady-state energy flow analysis method and device for an electricity-gas comprehensive energy system are good in accuracy, low in calculation amount and high in calculation efficiency.

The invention designs an equivalent modeling method suitable for an ISOP type DC-DC converter composed of DAB. According to the core technical scheme, the method comprises the steps that 1, inductance, capacitance and transformer elements of all DAB are discretized through a trapezoidal integral method, and a DC-DC converter accompanying network is formed; 2, a cut set network equation is listed,the internal nodes of the DAB unit and the internal nodes of the DC-DC converter are sequentially eliminated by utilizing the thought of a fast nesting solving algorithm, and an equivalent circuit expression of the DC-DC converter is obtained through equation transformation; 3, the equivalent circuit of the DC-DC converter is combined with an external circuit, and external node information is solved by using an electromagnetic transient simulation program; and 4, the port and internal node information of the DAB unit are inversely solved.

The invention provides a static model and steady power flow analysis method of a more electric aircraft electric system. The electric system comprises a power flow model wiring diagram composed of a generator model, a converter model, an electric transmission line model, a load model, a filter and reactive compensation model, and en energy storage device model. The method is based on an AC / DC power flow computing method of a land electric system and in consideration of a feature that a DC bus carries the DC load at the same time, a DC equation in an improved network equation is adopted so as to fit the power flow computing analysis of the more electric aircraft electric system, and the power flow distributions of the aircraft electric system under different working conditions are computed through MATLAB programming. Through the adoption of the method provided by the invention, the steady state of the more electric aircraft electric system can be researched on the whole, the method pays more attention to the system integrity, and is capable of clearly analyzing the power flow distributions under different flight working conditions.

The invention provides a VSC-based UPFC electromechanical transient modular modeling method. The method includes the steps of (1) unifying VSCs of different topological structures into the same equivalent commutation circuit; (2) dividing a UPFC into a series module, a parallel module, a DC module and a control module; (3) according to different series and parallel combination modes, determining the sequence of calculation of the modules of the UPFC and calculating sequentially; and (4) alternatively solving for the UPFC part and a network equation. The invention divides the UPFC into the series module, the parallel module, the DC module and the control module which can be freely combined, therefore has a very high flexibility, and can be adapted to a variety of UPFC power grid accessing modes and using scenarios.

The invention discloses an auxiliary decision-making calculation method for eliminating overload of near-zone equipment of a unified power flower controller (UPFC). A UPFC module and a network equation are alternatively iterated by power flow calculation on UPFC power flow control, an active power flow setting value of a series connection end of the UPFC is automatically adjusted according to a relative relation between control adjustment of active power flow of the series connection end in iteration and overload quantity of a controlled component when a controlled voltage source of the seriesend is not limited, the UPFC power flow is finally controlled within an adjustable range, and the static unsafety of the near-zone equipment of the UPFC is eliminated. By the auxiliary decision-making calculation method, a control strategy of the UPFC can be rapidly calculated on the premise that the effectiveness of eliminating the overload of the controlled component by UPFC power flow controlis ensured, the problem that an injection quantity perturbation method used for calculation of traditional static safety auxiliary decision making is not suitable for a strong non-linear controlled component such as the UPFC is solved, direct perturbation of a UPFC control target is also prevented, and the power flow calculation is short in time.

The invention relates to a finite time planning method for a cooperated repeated motion of a double arm manipulator. The method comprises the following steps: 1) determining expected target tracks ofleft and right end executors of a double arm manipulator and angular expected folding angles of joints of the double arm manipulator; 2) designing a secondary optimization index to form a double arm manipulator cooperated repeated motion planning scheme, wherein an initial joint angle of the double arm manipulator in action motion can be appointed randomly; 3) introducing an initial correcting factor to construct a final state network model converged by a finite time and solving a time varying problem by means of a network equation; and 4) sending a calculated result to a controller to controlthe cooperated repeated motion of the double arm manipulator. The method is relatively high in precision and converges at the appointed time. When the initial positions of the joint angles of the left and right arms deviate from expected positions, after the moving joint angles of the double arm manipulator finish track tasks, the double arm manipulator can return to the initial expected positionwithin the appointed finite time to achieve a repeated moving task.

The invention relates to a heat supply network waterway modeling method for comprehensive energy system scheduling, and belongs to the technical field of operation control of comprehensive energy systems. According to the method, a hydraulic analysis model and a power network model are unified, and a relationship between a hydraulic dynamic state and a hydraulic steady state is established. The method is based on characteristic equations of a heat distribution pipeline, a flow control valve and a booster pump. The method comprises: abstracting waterway element models such as water resistance,water inductance and a water pressure source, establishing hydraulic branch characteristics of a heat supply network based on the waterway elements, establishing hydraulic topology constraints of theheat supply network based on Kirchhoff-like voltage and current laws, and finally establishing a steady-state hydraulic network equation by combining the hydraulic branch characteristics and the hydraulic topology constraints. The method is clear in physical significance, covers various devices such as a heat distribution pipeline, a flow control valve and a booster pump, comprehensively considersheat supply network branch characteristics and topological constraints, is high in modeling method applicability, and facilitates unified scheduling of a heat heterogeneous energy flow system and anelectricity heterogeneous energy flow system.

The invention discloses a single-end holographic frequency domain fault positioning method for a high-voltage transmission line. Starting from a fault component network equation, opposite-end system impedance, transition resistance and a fault distance are set to be undetermined parameters, a network equation in the frequency domain under a lumped parameter model is given, and system parameters and the positioning information are obtained through solution. The method eliminates systematic errors in single-end range measurement from the principle, and the range measurement precision is improved.

The invention relates to a power system short circuit current attenuation calculating method based on coordinate transformation. The method includes the following steps 1) acquiring an initial node voltage equation, and correcting the initial node voltage equation to obtain the corrected node voltage equation; 2) performing the real-number expression on the corrected node voltage equation; 3) obtaining the network equation of a rotary motor by the coordinate transformation according to the real-numbered node voltage equation, and respectively obtaining the equivalent injection current equation of a generator and the corresponding node of the motor according to the network equation of the rotary motor; 4) respectively obtaining the attenuation potentials of the generator and the motor according to the potentials of the generator and motor before the short circuit and the calculation equation of the rotary motor stator current; 5) calculating the short-circuit voltage of each node according to the attenuation potentials of the generator and the motor; and 6) acquiring the short circuit current of the short circuit nodes. Compared with the prior art, the power system short circuit current attenuation calculating method has the advantages of comprehensive consideration, accurate calculation, and closeness to reality.

The invention relates to a 0+ error immune electromagnetic transient simulation algorithm used under the sudden change of input quantity and belongs to the technical field of electromagnetic transient analysis of an electric system. According to the method, by means of the impulse response invariable principle, numerical sampling of a continuous signal of the system corresponds to Z conversion of a discrete signal, and the fundamental form of an element based on operation conductance and a history current item is given. Based on the form, a system network equation is obtained according to the node analysis method, and a system electromagnetic transient simulation result is obtained according to the same steps. The method has the advantages that the truncation error is smaller than that generated through currently adopted methods and the 0+ error purpose is realized under the sudden change of the immune input quantity, achieves non-linear load modeling of the electric system, solves the problem of oscillation of an electronic power switch model state variable outburst value, and provides a new way for electromagnetic transient branch-level modeling of the electric system.

The invention provides a transient stability network equation algorithm based on full-pure embedding, and the algorithm comprises the steps: taking a node voltage equation and a generator voltage equation which are represented by a real part and an imaginary part and contain a non-linear load, and carrying out the joint elimination of a power grid current through the two equations, thereby obtaining a non-linear network equation; introducing an all-pure embedding factor into the nonlinear network equation, and enabling a voltage variable to be solved in the nonlinear network equation to be an all-pure function about the all-pure embedding factor; calculating a virtual current expansion item of the generator according to a non-linear network equation in a full-pure function form, and solving various coefficients of a voltage variable item by item; and seleceting a numerical approximation method, and restoring the voltage variable according to various coefficients of the voltage variable. According to the transient stability network equation algorithm, the problem that the load current is not synchronous in time during constant power load can be solved, the coefficient of the expansion item of the target variable analytical expression is obtained by solving the linear equation set of the same coefficient matrix for multiple times to restore the target variable, and the problem that a nonlinear system needs to be solved is avoided.

The invention provides an analysis method for analyzing the dynamic and reactive power control interactive impact in a wind power convergence region. The analysis method comprises the steps of forming a node admittance matrix and a network equation according to a spatial grid structure in a to-be-analyzed wind power convergence region; establishing a dynamic equation and an output equation of a dynamic reactive power compensation device according to the control mode of the dynamic reactive power compensation device in the to-be-analyzed wind power convergence region; according to the network equation, the dynamic equation and the output equation, forming a linear differential equation and a linear state matrix of the to-be-analyzed wind power convergence region; according to the linear state matrix, acquiring the characteristic roots of the dynamic reactive power compensation device in different control modes; and based on the participation vector analysis of the characteristic roots, generating an analysis result for analyzing the dynamic and reactive power control interactive impact in the to-be-analyzed wind power convergence region.

The invention provides a method for restraining electromagnetic transient simulation virtual power consumption of a controllable power electronic device. The method comprises the following steps: establishing a network equation containing the controllable power electronic device; defining the pulse triggering time tz of the controllable power electronic device, obtaining a current source I<tz-delta t> injected by a system during network re-calculation at the tz; obtaining the network node voltage at the pulse triggering time through the I<tz-delta t>; performing iterative integration of simulation step size, and returning interpolation to standard step size. Through the adoption of the method, the virtual power loss caused by the pulse triggering action of the controllable power electronic device is effectively avoided, and the simulating capability of the controllable power electronic device is improved.

The invention belongs to the research field of micro-grid application, and relates to a micro-grid small signal stability analytical method, in particular to a small disturbance stability analytical method used for selecting a network equation type according to micro-grid line voltage classes in order to establish a system state space model. In accordance with a micro-grid typical line 400V and 10kV, a circuit type is selected first, then different network equations are chosen according to the two sorts of voltage classes so that the system state space model can be established, in this way, small signal stability analysis is conducted, the conditions of droop gain change, load change, line impedance change and the like can be analyzed, and thus a basis can be provided for stability control over the micro-grid.

The invention relates to an electromagnetic transient simulation initialization method, which is technically characterized by comprising the following steps: constructing a node network equation of athree-phase unbalanced AC / DC hybrid power grid of a new energy station; constructing a new energy field station three-phase imbalance AC / DC hybrid power grid model based on a BP neural network according to the node network equation, and nesting load flow calculation iteration of the BP neural network; and improving the computing efficiency of the three-phase fundamental wave power flow through a multi-port equivalence-based parallel computing method. On the basis of a new energy field station sequence component model, the imbalance state of the three-phase AC / DC hybrid power grid is initialized and corrected, so that an initial point is closer to a steady-state point to improve the speed of numerical calculation; effective power flow initialization can improve the efficiency of electromagnetic transient simulation and the stability of numerical calculation, and the feasibility of power flow calculation engineering of a new energy station is improved; and according to the parallel computing method based on multi-port equivalence, the electromagnetic transient simulation initialization speed is increased, numerical convergence is fast, and interference is small.

The invention discloses a method and device for determining a characteristic curve of a pipe network. A present combination type of circulation equipment in a pipe network water system and a correspondence table between the combination types of the circulation equipment and characteristic parameters of the pipeline are obtained; according to the present combination type of the circulation equipment, a target pipe network characteristic parameter corresponding to the present combination type of the circulation equipment is obtained from the correspondence table; and according to the target pipe network characteristic parameter and a pipe network equation corresponding to the pipe network water system, the pipe network characteristic curve of the pipe network water system is obtained. Thus, a new ideal for determining the pipe network characteristic curve is provided from the aspect of the combination type of the circulation equipment, the target pipe network characteristic parameter corresponding to the present combination type of the circulation equipment can be obtained rapidly and accurately according to the correspondence table, and thus, the pipe network characteristic curve can be determined more efficiently and more accurately.