138 results about "Nodal admittance matrix" patented technology

The invention provides a three-phase imbalance three-phase imbalance method for a power distribution network with distributed power supplies. The three-phase imbalance three-phase imbalance method for the power distribution network with distributed power supplies comprises: aiming at the complex power distribution network, on basis of the fundamental principle of the implicit Gaussian load flow calculation method.

Three phase power flow analysis of an unbalanced power distribution system decouples voltage changes resulting from nodal admittance matrix into one contribution from a real part, conductance matrix, and other contribution from an imaginary part, and a susceptance matrix. A first voltage change and second voltage change resulting from conductance and susceptance matrices are determined respectively. The voltages of a node of the power distribution system are determined as a combination of first and second voltages.

The invention provides a method for calculating harmonic wave impedance of an alternating current system for direct current transmission. The method includes the following steps that a node admittance matrix is formed according to a harmonic wave model of a transmission line, a transformer, a generator, a load and a parallel capacitor; nodes to be calculated are placed at the bottom line of the admittance matrix, the current value at the bottom line is set to be 1, and the current values at other lines are set to be 0; node optimizing numbering is conducted on the first n-1 nodes; the node admittance matrix is stored through a sparse technology; the node admittance matrix is solved, and the back substitution does not need to be conducted; a plurality of input files are simultaneously calculated through a parallel calculation method; statistic analysis is conducted according to the batch processing calculation result. According to the method, specific to the characteristic that multiple times of scanning needs to be conducted for calculating the harmonic wave impedance, the improved node optimizing numbering technology and the improved sparse technology are adopted, and therefore the workload for calculating the harmonic wave impedance is reduced, the calculating speed is greatly increased, burdens of operators are relieved, and precious time can be saved.

The invention provides an accurate linearization method of a measurement equation for electric power system state estimation. The accurate linearization method is characterized by including steps of establishing a network model and calculating a nodal admittance matrix; selecting state vectors and measurement vectors; and forming a jacobian matrix so as to get the accurately linearized measurement equation. The accurately linearized measurement equation is obtained by selecting the state vectors and the measurement vectors, and the state vectors can be solved by means of any types of existing state estimation according to the accurately linearized measurement equation, and estimation values such as all branch power and node injection power in the network can be acquired, so that complexity of the state estimation model is reduced greatly and the equation is easy to solve.

The invention discloses a method for comprehensively optimizing energy storing power station planning and operating. The method comprises the first step of constructing a real-part matrix G and a virtual matrix B of a node admittance matrix used for carrying out load flow calculation according to network parameters of an electric power system and determining the upper limit value and the lower limit value of voltage of all nodes and the upper limit value and the lower limit value of all line power flow when the electric power system operates safely and stably, the second step of determining the upper limit value and the lower limit value of work output of a common electric generator, determining generating cost parameters of the common electric generator, determining the upper limit value and the lower limit value of the work output of a wind turbine generator or a wind power motor field and determining the penalty electricity price for draught fan fault according to the power source parameters of the electric power system, the third step of determining the capacity price, the power price and the average service life of an energy storage system and daily maintenance charge according to parameters of the energy storage system, the fourth step of determining the typical day wind power predicted data of the wind turbine generator or the wind power motor field, determining the day load data, determining the backup data of rotating of the electric power system and determining the transmission loss price of the electric power system according to scheduling operating data of the electric power system, and the last step of determining an inner layer optimization model and an outer layer optimization model according to the data collected in the first step, the second step, the third step and the fourth step.

An embodiment of the invention provides an electric-power-system robust state estimation method based on a subsection nonlinear weight function and an apparatus thereof. The method comprises the following steps of constructing a node admittance matrix of an electric power system, a measurement amount measurement equation and a zero injection equality constraint; calculating a jacobian matrix and a measurement-amount residual error of the electric power system and acquiring a weight of each measurement amount; and updating a state variable, determining whether an iteration algorithm reaches a convergence threshold, and if the iteration algorithm reaches the convergence threshold, acquiring a final node voltage amplitude and a phase position of the electric power system. In the invention, bad data detection and identification, and state estimation are simultaneously performed; state estimation calculating is performed, and simultaneously a measurement amount weight can be changed; a bad data weight in iteration is continuously reduced and an influence brought by the bad data is restrained; a calculation amount is effectively reduced and work efficiency is increased; a residual error of the measurement amount is directly introduced into a subsection nonlinear weight function, and standardized residual error calculating is avoided so that a calculating speed can be greatly increased and calculating time is saved; and the method and the apparatus are suitable for an engineering application.

The invention relates to a network voltage sag frequency estimation method and device with a distributed power supply. The method comprises the following steps: calculating a node impedance matrix according to a node admittance matrix of the system; calculating the self-impedance and mutual impedance at the fault point after short circuit occurs in the system; calculating the voltage sag amplitudeof the estimated busbar under different fault types; determining the voltage sag duration of the estimated busbar; performing statistics of the sag frequency of the estimated busbar according to thevoltage sag amplitude and the voltage sag duration of the estimated busbar. According to the method and device provided by the invention, the estimation accuracy of the voltage sag with a distributedpower supply system is improved; by adopting kernel density estimation, the distribution law of the fault occurrence positions better conforms to the practical situation according to the history faultinformation, thus the estimation result of voltage sag is more accurate and conforms to the practice.

The invention discloses a rectangular coordinate Newton load flow calculation method; from the basic principle of rectangular coordinate Newton load flow calculation, the invention provides a composition method of Jacobimatrix calculated by rectangular coordinate Newton load flow calculation to improve the convergence of load flow calculation on the basis of analyzing the characteristics of basic modified equation. The method comprises the following steps: inputting original data and initializing voltage; forming nodal admittance matrix; forming Jacobimatrix J; solving the equation and correcting the real part e and the imaginary part f of voltage; and outputting nodal and subcircuit data. The invention corrects partial diagonal element calculation formula of Jacobimatrix J, solving the problem of convergency of rectangular coordinate Newton load flow calculation method when analyzing a subcircuit system containing low impedance; the iterations, possession of the amount of internal memory and arithmetic speed in the invention are all equivalent to conventional rectangular coordinate Newton load flow calculation method when treating system with no low impedance, so the calculated amount is not increased, but is slightly reduced on the contrary.

The invention provides a general method for calculating the tide of positive power distribution networks. The general method comprises the step of establishing various distributed generation (DG) tide calculation models to obtain a PV node sensitivity reactance matrix BPV of nPV PV type DG positive power distribution networks so as to calculate the tide of the positive power distribution networks. The general method is high in universality, can be used by power distribution networks with various wiring modes and operating modes, and also can be used for calculating the tide of power distribution networks at disconnected areas; the topological analysis of the power distribution networks is not needed, various path matrixes do not need to be calculated, and a node admittance matrix can be directly figured out according to node information and branch information, so that the general method is simple and is easy in implementation; the accurate PV node sensitivity reactance matrix is adopted, so that the convergence speed of reactive power output of the PV node type DG is enhanced; on the basis of a Zbus method, the calculation of the whole convergence speed is fast, and the stability is good; the generable method can be expanded to calculation of three-phase tides.

The invention provides a method of calculating an equivalent circuit, which reduces the number of elements constituting a network to a large extent with a target accuracy secured. The method of the invention calculates an equivalent circuit by a computer, with regard to an object that has a conductor, a dielectric to support the conductor, and plural input/output terminals to the outside. Step 1 in the method receives inputs of geometry information to specify a shape of a conductor in a circuit board being the object of determining the equivalent circuit, and material information to specify a material of the circuit board; Step 2 partitions the shape of the objective conductor into meshes on the basis of the geometry information received, and creates mesh data to be expressed; Step 3 calculates a nodal admittance matrix from the mesh data, and stores the result; step 4 calculates the number of nodes and the number of independent networks on the basis of the mesh data, determines an incidence matrix, and determines the structure of an equivalent network by means of the calculated nodal admittance matrix and incidence matrix; and Step 5 determines the values of elements of the equivalent network.

The invention relates to a method for extracting resonance information of a long-line wind farm grid connection, comprising the following steps: 1) establishing an equivalent model of a wind farm grid connection; 2) obtaining the wind farm grid connection system according to the wind farm grid connection equivalent model Nodal admittance matrix; 3) decompose said nodal admittance matrix into expressions about eigenvalues: Y _f = LΛT; 4) According to step 3), the resonance participation factor of each node and the resonance sensitivity value of each electrical component are obtained when the long-line wind farm grid-connected resonance phenomenon occurs. Compared with the prior art, the present invention is based on the equivalent model of wind farm grid connection, and uses modal analysis method to analyze the resonance participation factors of each node of the system and the modal sensitivity of components, thereby giving detailed wind power grid connection resonance information, providing wind power It provides theoretical guidance for field construction planning, and has the advantages of accurate and reliable information extraction results.

The invention provides a method of analyzing the resonance stability of a flexible DC transmission access system. A node admittance matrix of the flexible DC transmission access system is analyzed, the resonance mode of the system is determined, and the stability of the system is further judged. In view of the application scene of analyzing the resonance stability problem of the flexible DC transmission access system, the flexible DC transmission access system resonance stability analyzing method can comprehensively analyze the resonance mode existing in the flexible DC transmission access system, and the stability of the system is judged. The resonance stability judgment method overcomes the problems of a large workload and unknown parameters of a state space method, and in comparison with an impedance analysis method, the scanned resonance mode is more complete, the stability of the whole system is more accurately judged, and some reference and guidance are provided for actual engineering planning and construction of the flexible DC transmission engineer.

The invention provides a nonlinearity-considered electromagnetic transient real-time simulation method of a transformer substation. The method comprises the following steps: preparing for simulation off line; differencing transformer substation elements according to the selection of simulation step size delta t; converting electric network of the transformer substation elements into corresponding an adjoint network through an adjoint circuit; reordering a differenced nodal admittance matrix according to the nonlinear local iterating principle and the minimum degree independent set method; arranging instructions performed by an arithmetical unit according to the idea of solving a nodal voltage equation by the gauss elimination; calculating real-time simulation on line, wherein the online calculation specifically includes the historical current source calculation of the adjoint circuit, the nodal injection current of the adjoint network, the order elimination of the nodal voltage equation, reversed order back substitution of the nodal voltage equation, branch voltage calculation and branch current calculation which are processed in parallel through a plurality of arithmetical units; quickly simulating parameter read-write interaction between the arithmetical units and a data storage space by the simulation parameter decoding query method. With the adoption of the method, the real-time performance of electromagnetic transient real-time simulation of the transformer substation can be ensured.

The invention relates to a WARD equivalence-based alternating current direct current system equivalence method. The alternating current direct current system equivalence method comprises the steps ofestablishing each basic element model, obtaining nodes in the whole network to be used as basic data, and determining the data format; performing power flow calculation on the whole network and obtaining the power flow solution of the whole network; dividing the nodes into an internal node set, a boundary node set and an external node set, wherein the elements in each set are arranged from small to big based on node numbers; forming a node admittance matrix of the whole network, and forming partitioned node admittance matrixes used for equivalence calculation according to the divided node sets; calculating an equivalence matrix, a boundary equivalence capacitor and a boundary equivalent injection power; forming a new structural data body, and storing the basic data of the system after equivalence to be defined as R<empc>; and performing power flow calculation on the system after equivalence, making comparison on the power flow results of the retained branch and the nodes before and after equivalence, and selectively outputting the power flow results. By virtue of the alternating current direct current system equivalence method, it is effectively ensured that the power flow error ofthe retained system before and after equivalence can be in the minimum, so that the method can be applied to an extra-high voltage direct current layering system.

The invention discloses an alternating-current and direct-current interconnected power grid Thevenin equivalent parameter online calculation method. The method includes the steps that equivalent impedance or equivalent current source processing is conducted on a direct-current power transmission unit in an alternating-current and direct-current interconnected power grid according to PMU measurement values to obtain a primary correction admittance matrix; equivalent impedance processing is conducted on the load of current state load nodes in the alternating-current and direct-current interconnected power grid to obtain a secondary correction admittance matrix after equivalent impedance processing; load impedance at the current state load node in the alternating-current and direct-current interconnected power grid is cut off, and a node admittance matrix for open-circuit voltage is calculated according to the secondary correction admittance matrix; according to the node admittance matrix for open-circuit voltage and node state information of all nodes in the current state, a node voltage equation for open-circuit voltage is calculated; Thevenin equivalent impedance is calculated, and accordingly all Thevenin equivalent parameters of researched load nodes in the alternating-current and direct-current interconnected power grid can be obtained.

A method analyzes a fault of an ungrounded power distribution system. The method determines a type of a fault in a line segment of the ungrounded power distribution system, and modifies a nodal admittance matrix of the line segment determined before the fault using a transformation matrix corresponding to the type of the fault to produce a faulty nodal admittance matrix of the line segment after the fault. The ungrounded power distribution system is analyzed using the faulty nodal admittance matrix and nodal admittance matrices of functional branches or line segments of the power distribution system.

The invention discloses a power system harmonic state estimation method based on an automatic differentiation. The automatic differentiation (AD) technology is applied to the power system harmonic state estimation. The method includes that firstly storage allocation is performed for the AD, live variables are described, a network parameter is obtained, a harmonic number is set, and a node admittance matrix of a harmonic is formed; then before iteration, positions and values of invariant elements in a jacobian matrix are stored in a linked list; and the iteration starts, the AD tool is used to calculate variable elements in the jacobian matrix, and simultaneously the invariant elements of the jacobian matrix in the linked list are read to obtain the jacobian matrix required by the harmonic state estimation. According to the power system harmonic state estimation method based on the automatic differentiation, traditional manual differential code writing is replaced by the AD to calculate the jacobian matrix, thereby handwritten code quantity is reduced, development efficiency of programs is increased, truncation error is effectively avoided, computational efficiency of algorithm is improved, and the power system harmonic state estimation method based on the automatic differentiation is convenient to implement on an existing state estimation software.

The invention discloses a method for acquiring the harmonic characteristics of a power grid containing new energy stations, which is characterized by comprising the following steps: establishing a node admittance matrix of a linear network part; acquiring frequency response data of equivalent admittance of new energy stations by simulation or field test, and using the frequency response data to form supplementary admittance matrixes of the new energy stations at different frequencies; including the supplementary admittance matrix of each new energy station in the node admittance matrix of thelinear network part to form a node admittance matrix of the whole power grid; and acquiring the harmonic distribution of the whole power grid under harmonic disturbance according to the node admittance matrix of the whole power grid, and evaluating the harmonic distortion and overvoltage risk of the power grid. The need for harmonic characteristic analysis is satisfied.

The invention provides a method for quickly solving a nodal impedance matrix of a power system, and relates to the field of analytical computation of the power system. The method mainly comprises the following steps of inputting data of a nodal admittance matrix Y; establishing an augmented matrix B by the nodal admittance matrix Y and an identity matrix E together; normalizing the augmented matrix B and carrying out a Gauss-Jordan elimination method on the augmented matrix B for n times; obtaining an inverse matrix Z. At present, traditional methods for solving the nodal impedance matrix comprise an LDU (Logic Data Unit) triangular decomposition method and a Gauss elimination method, and compared with the two traditional methods, the novel method for quickly solving the nodal impedance matrix by utilizing the Gauss-Jordan elimination method, provided by the invention, has the advantages that the principle is simple and easy to understand, the computation time is reduced, the programming is convenient, and the like; compared with the traditional LDU triangular decomposition method and the Gauss elimination method, by utilizing the method for verifying systems such as an IEEE-57 node, an IEEE-118 node and an IEEE-300 node, the computation speeds can be respectively increased by about 25%-50%.

The invention provides a visualization method and device for electrical distance of a power system. The method comprises the steps of calculating a self-impedance matrix of a node according to a power grid topology and a running parameter, which are acquired in advance, of the power system by a node admittance matrix inversion method; mapping high-dimensional space data to a low-dimensional space by a t-SNE algorithm according to the self-impedance matrix to calculate the electrical distance; and drawing a pattern relevant to the electrical distance of the power system according to node coordinates obtained by calculation of the low-dimensional space. The device comprises a matrix building unit, a dimension reduction unit and a drawing unit. With the technical scheme provided by the invention, the tightness degree among different equipment can be fully displayed, and an intuitive object can be given to an operator.

Disclosed is a design method of a real-time simulation solver of an active power distribution network on basis of an FPGA. The method comprises the steps of offline preprocessing and online solving. During offline preprocessing, a column approximate minimum degree algorithm is adopted for processing a node admittance matrix; the address vectors of current and the address vectors of current voltageare prestored; an LU decomposition method is adopted for decomposing the node admittance matrix; the starting time of each sub-task in the previous substitution process and the back substitution process is prestored. During online solving, the simulation starting time is set; the simulation time is advanced by one step length; information initialization of each sub-task and addressing sorting ofthe current vectors are completed; when solving begins, a starting timer of each processing unit is initialized according to the prestored starting time of the corresponding sub-task; solving in the previous substitution process is completed, and an intermediate solution vector is generated; solving in the back substitution process is completed, and a final solution vector is generated after addressing sorting; whether or not the simulation time reaches the final simulation moment is determined. By means of the method, while the solving precision and speed are ensured, sparse linear equationsare solved accurately and efficiently.

The invention provides a flow-based voltage supporting ability evaluation method of a multi-infeed direct-current receiving-end power grid. The method comprises the following steps: (A) calculating flow of the multi-infeed direct-current receiving-end power grid; (B) constructing a nodal-admittance matrix Y of a receiving-end alternating-current power grid; (C) calculating a nodal-impedance matrix Z, which is an inverse matrix of the nodal-admittance matrix Y; (D) calculating voltage supporting ability evaluation indexes of a to-be-inspected direct-current power transmission system feed node; and (E) evaluating the voltage supporting ability of the to-be-inspected node. According to the flow-based voltage supporting ability evaluation method, the problem of no voltage supporting ability evaluation method suitable for a general multi-infeed direct-current receiving-end power grid at present is solved.

The invention provides a power grid robust state prediction method based on multi-dimensional state matrix sliding matching. The power grid robust state prediction method comprises the steps of obtaining a node admittance matrix; acquiring SCADA instrument quantity measurement and PMU device quantity measurement, and constructing a state quantity set based on mixed state estimation; forming a historical state quantity database; predicting the future state of the nodes of the smart power grid by using a multi-dimensional state matrix sliding matching method to obtain a prediction result; adopting an improved power balance equation detection method to detect whether abnormal data exists in a current system or not, if yes, a residual distribution deviation degree detection method is adopted to judge whether the abnormality is caused by abrupt change of quantity measurement, if yes, correction is carried out, bad data are removed, and reliable data support is provided for state predictionin future. The method has better prediction robustness, information in a historical database can be effectively utilized, and the safety and reliability of the intelligent power grid and the capability of resisting malignant data and bad data are improved.

The invention relates to a power system broken line impedance scanning method and device. The method comprises the following steps that line information of a power system network is obtained, node information of all nodes in the power system network is obtained according to the line information, and a node admittance matrix of the power system network is calculated according to the node information; target lines, meeting preset constraint conditions, in lines of the power system network are determined, and parameter information of all the target lines is obtained; broken line impedance computing tasks of all the target lines are generated according to the parameter information of all the target lines and the node admittance matrix, and the tasks are mapped to corresponding threads of a graphics processor; in all the threads of the graphics processor, broken line impedance of all the target lines is obtained through parallel computing. According to the technical scheme, when broken lineimpedance scanning of the multiple target lines and particularly large power network lines complex in structure is conducted, the operating rate can be significantly increased, and the broken line impedance of the target lines of the power system network is obtained rapidly.

The invention discloses a weight function least square state estimation method based on residual normalization, and belongs to the field of electric power system dispatching automation. The method comprises the steps that SCADA data, collected by a data terminal, of any time section, a network structure and parameter information are input firstly through a computer and a program and initialized; a node admittance matrix of a network is calculated, a zero-injection equality constraint equation is formed, and then a corresponding residual, a jacobian matrix and a weight function are calculated by comprehensively considering a voltage amplitude value measuring equation, an injection power measuring equation and a branch circuit power measuring equation and taking the node voltage amplitude value and phase angle as state variables; finally, the state variables are updated, convergence judgment is conducted, and the state estimation of a power grid is achieved. By means of the weight function least square state estimation method based on residual normalization, bad lever measurement can be effectively restrained, high robustness and good convergence are achieved, the computational efficiency is very high, and a good engineering application prospect is achieved.