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32 results about "Superposition theorem" patented technology
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The superposition theorem for electrical circuits states that for a linear system the response (voltage or current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, where all the other independent sources are replaced by their internal impedances.
Method for predicting electrical properties of deformed log-periodic antennae based on electromechanical coupling model
InactiveCN102253290AAccurate analysisRealize the structureElectrical testingAntenna designElement model
The invention discloses a method for predicting electrical properties of deformed log-periodic antennae based on an electromechanical coupling model, aiming to mainly solve the problem of electromechanical separation in the log-periodic antennae. The method comprises the following steps: building a finite element model based on the structural design parameters of the log-periodic antennae, loading dead load, random wind and other environmental loads and carrying out finite element analysis to obtain the structure displacement field of the log-periodic antennae; utilizing the analysis results to obtain current distribution of oscillator units in the log-periodic antennae and phase difference caused by the positions and deflection of the oscillator units and computing the far field patternsof the log-periodic antennae according to the superposition theorem; and obtaining the electrical property parameters of the log-periodic antennae to realize electromechanical coupling analysis of the log-periodic antennae. The method can help the log-periodic antenna structural design personnel improve the antenna design and manufacturing quality.
Owner:王从思
Evaluation method for distance protection performance of mixed direct current feeding alternating current system
ActiveCN106711972ASmooth connectionHigh precisionEmergency protective circuit arrangementsTransient stateElectric power system
The invention discloses an evaluation method for distance protection performance of a mixed direct current feeding alternating current system. The method comprises the following steps: utilizing the characteristics of a mixed multi-feed direct current transmission system to enable a conventional direct current transmission system and a flexible direct current transmission system before the fault to be equivalent to a constant current source; enabling the conventional direct current transmission system and the flexible direct current transmission system after the fault to be equivalent to a controlled current source; subtracting the constant current source in a network before the fault from the controlled current source in the network under a normal condition after the fault equivalent to the conventional direct current transmission system and the flexible direct current transmission system in a fault component network; and adopting a transient state principle for acquiring a short circuit current at a fault point, thereby utilizing a superposition theorem to acquire the variation of voltage and current on a protecting mounting position in the fault component network, further acquiring the measured impedance and verifying the protection sensitivity. The defects of an evaluation scheme for the distance protection performance characteristics in a mixed multi-feed direct current transmission system model and an alternating current system connected with the mixed multi-feed direct current transmission system model in a traditional electrical power system equivalent model can be overcome.
Owner:国家电网公司西南分部 +1
Loop closing power supply operation risk assessment method for power distribution network
InactiveCN108304613AImprove power supply reliabilityImprove economyDesign optimisation/simulationSpecial data processing applicationsLoop closingPower factor
The invention discloses a loop closing power supply operation risk assessment method for a power distribution network. The method comprises the steps of 1: analyzing the type of a loop closing mode; 2: properly adjusting values and power factors of loads on two sides of a loop closing point; 3: ensuring a sum of the loads on the two sides of the loop closing point not to exceed a rated load of oneof switches on the two sides; 4: according to a superposition theorem, calculating line power flow after loop closing, and calculating a phase difference and a voltage of the two sides of the loop closing point; and 5: calculating a loop closing impact current and a loop closing steady-state current, performing safety check on all devices on the loop by utilizing the loop closing impact current and the loop closing steady-state current, and judging whether the loop closing can be performed or not. According to the method, the power supply reliability can be improved; better services can be provided for users; the power supply reliability of the power distribution network can be enhanced; the power supply flexibility of the power distribution network is ensured; the economy of power distribution network operation is improved; and remarkable social and economic benefits are achieved.
Owner:GUIZHOU POWER GRID CO LTD
Calculation method for high-frequency harmonic power flow of active power distribution network
ActiveCN106655195AEasy to formulateAccurateAc networks with different sources same frequencyHarmonic controlVoltage source
The invention provides a calculation method for high-frequency harmonic power flow of an active power distribution network, aiming at the problems of how to calculate the high-frequency harmonic power flow of the active power distribution network, and no related calculation methods in the prior art. The calculation method comprises the steps of 1) obtaining a high-frequency harmonic impedance model of each component; 2) performing equivalence on high-frequency background harmonics and voltage source and current source type grid-connected inverters; 3) calculating harmonic voltages of to-be-calculated nodes of the active power distribution network during separate action after equivalence; and 4) obtaining the high-frequency harmonic power flow of the to-be-calculated nodes by utilizing a superposition theorem. According to the method, the high-frequency harmonic power flow of the active power distribution network is obtained by utilizing an equivalent high-frequency harmonic model of the active power distribution network and the superposition theorem in electrotechnics, so that high-frequency harmonic power flow distribution can be mastered more accurately and harmonic control measures can be better established for reducing harmonic control cost and influence on a power system; and therefore, the method has a very important effect for research and development of the active power distribution network.
Owner:ELECTRIC POWER RES INST OF STATE GRID ANHUI ELECTRIC POWER +3
Power frequency electric field acquisition method based on the periphery of a high-voltage transmission line
PendingCN109918813AImprove calculation accuracyStrong field adaptabilitySpecial data processing applicationsVoltage vectorComputational physics
The invention relates to a power frequency electric field acquisition method based on the periphery of a high-voltage power transmission line, and the method comprises the following steps: S10, enabling the power transmission line to be simplified meeting the engineering precision requirement in order to facilitate the calculation and analysis of the electric field distribution around the power transmission line; S20, calculating a potential coefficient matrix of the power transmission line by resetting analog charges and matching point positions in the simplified model of the power transmission line; and S30, calculating the charges of the wire per unit length according to the potential coefficient matrix and the voltage vector, obtaining an electric field generated by the charges by using a superposition theorem, finally verifying the calculation precision, and repeating the step S20 if the calculation precision does not meet the requirements. Compared with the prior art, the methodhas the advantages of relatively high calculation precision and the like.
Owner:SHANGHAI MUNICIPAL ELECTRIC POWER CO +1
Direct current grid fault current complex frequency domain calculation method
InactiveCN110108986AHigh precisionFault location by conductor typesInformation technology support systemNew energyAlternating current
The invention provides a direct current grid fault current complex frequency domain calculation method. In the technical field of power transmission and distribution, a direct current grid is used asan effective means to collect new energy sources such as wind power and photovoltaic energy resources, and the calculation of fault currents is of great significance for operation such as equipment type selection, protection design and parameter optimization. The fault current complex frequency domain calculation method is suitable for monopole and bipolar faults and is not affected by the transition resistance, the alternating current feed of the alternating current side after the fault and the direct current feed of a remote sound branch are fully considered, for the alternating current feedof a converter station, a superposition theorem is used for dividing the direct current grid into a normal network and a fault additional network, and the normal network and the fault additional network are solved separately; and for the direct current feed of a normal line branch, an external node of the fault additional network is statically equivalent, and an equivalent circuit is subjected tofault current solution in a complex frequency domain.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)
Out-of-step and oscillation center positioning and migration tracking system and method under multi-frequency oscillation
ActiveCN107611996AAchieve positioningVerify correctnessPower oscillations reduction/preventionVoltage vectorElectric power system
The invention belongs to the technical field of stability analysis of power systems and particularly relates to a position function-based out-of-step and oscillation center positioning and migration tracking system and method under multi-frequency oscillation. The method comprises the steps of connecting power supplies at three sides to a point through three lines to build a three-machine equivalent system model; obtaining a voltage vector expression of any point under the simultaneous action of the power supplies at three sides according to a superposition theorem; setting position functionsof oscillation centers according to line impedance ratios; rewriting the voltage vector expression of any point into a form of modulus and phase, expanding the expression into a quadratic function, calculating a partial derivative and then obtaining an expression of the position of the oscillation center at any side according to a trigonometric function relationship and a mean value inequality; and analyzing the influences of three factors, namely relative power angles of systems, impedance structure parameters and power supply voltage amplitudes of the systems on the oscillation centers, obtaining conditions of appearing of an out-of-step center at various sides, obtaining a criterion according to the trigonometric function relationship of one voltage vector and then determining the position of the out-of-step center.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)
Finite array antenna analysis method
ActiveCN106257465AAvoid calculationSmall amount of calculationDesign optimisation/simulationComplex mathematical operationsComputational problemFull wave
The invention discloses a finite array antenna analysis method. The method includes the following steps that the subarray solving scale is determined according to solving precision; full-wave solving is carried out on determined subarrays with a moment method; medium and large arrays are extrapolated according to the subarray solving result; in the process of solving subarray radiation fields, the subarray radiation fields are assumed to be radiation far fields, and an array antenna pattern is obtained. According to the method, based on the local effect of array antenna unit radiation fields and the electromagnetic field superposition principle, the numerical simulation issue of medium and large array antennas is simplified into full-wave solving of the subarrays according to the solving precision, then all unit radiation fields in the large arrays are equivalent to the unit radiation fields at corresponding positions in the subarrays, and finally based on the superposition theorem, the total radiation field is calculated, so that full-array matrix filling and the operation of solving the system of linear equations in the calculation process are omitted; besides, the radiation field calculation issue of the large arrays is transformed into the unit radiation field calculation issue of the small arrays, so that the calculation amount is effectively reduced, and the implementation difficulty is lowered.
Owner:CHINA SHIP DEV & DESIGN CENT
Frequency full-response analytical model considering initial state of system
ActiveCN110649596AWide range of application scenariosWidely availablePower oscillations reduction/preventionWind energy generationElectric power systemAnalytical expressions
The invention relates to a frequency full-response analytical model considering an initial state of a system. The model is characterized in that S1, a dynamic frequency full-response model is established according to a linearized model of each element of a power system and is simplified; S2, the initial state and input of the system are respectively ignored based on the full-response model in theS1, and analytic expressions of the frequency offset and the zero state response and zero input response of the power increment of a low-pressure cylinder in a steam turbine in the time period from tito ti+1 after a sudden change point i are obtained; S3, according to the superposition theorem, a full-response expression of the system frequency offset in the time period from ti to ti+1 after thesudden change point i is obtained through the S2; S4, i is made to be 1, and the process turns to a S5; S5, an analytical expression of the system frequency offset and the power increment of the low-pressure cylinder in the steam turbine in the time period from ti to ti+1 is solved; S6; if i is less than n, i is made to be equal to i+1, and the process turns to the S5; otherwise, the process turnsto a S7; and S7, an analytical expression of the whole dynamic frequency response process of the system is obtained. The model is advantaged in that the frequency response process of the system wheninput such as low-frequency load shedding and unit protection generator tripping occurs or parameters change suddenly when the frequency falls can be analyzed.
Owner:DALIAN UNIV OF TECH
Active power control method and system based on voltage sensitivity subarea
ActiveCN107508318ASmall amount of calculationClear control objectSingle network parallel feeding arrangementsPhotovoltaic energy generationEngineeringSuperposition theorem
The application provides an active power control method and system based on voltage sensitivity subareas; the method comprises the following steps: equivalently transforming the whole feed line in a distribution network system into a plurality of two-port network cascade so as to obtain a complex two-port transmission parameter matrix; respectively calculating voltage sensitivity photovoltaic contributed on other photovoltaic user grid connected point by each photovoltaic user grid connected point according to a superposition theorem and the complex two-port transmission parameter matrix, thus obtaining a voltage sensitivity matrix; dividing each the photovoltaic user grid connected point on the feed line into one or more voltage autonomous control area according to the voltage sensitivity matrix; when the feed line voltage exceeds a limit, calculating the active power reduction quantity of each the photovoltaic user grid connected point according to the voltage sensitivity of each the photovoltaic user grid connected point in the voltage autonomous control area to which the photovoltaic user grid connected point with the exceeded voltage is located.
Owner:NINGBO POWER SUPPLY COMPANY STATE GRID ZHEJIANG ELECTRIC POWER +1
Equivalent three-phase short circuit calculation method which considers outer network ground branch circuit and sensitivity information
ActiveCN107436995AHigh precisionAvoiding the problem of expanding the role of ground branchesInformaticsSpecial data processing applicationsNormal functioningComputer science
The invention discloses an equivalent three-phase short circuit calculation method which considers an outer network ground branch circuit and sensitivity information. Firstly, whole-network basic data including system element parameters, a topology structure and a trend calculation result under a normal running condition is input, then based on a sensitivity consistency equivalent method, an equivalent network is constructed, through a sensitivity weighing method, ground branch circuit admittance parameters are deducted, and according to trend, sensitivity and power transfer characteristic consistency, other parameters are solved. Finally, an improved equivalent method is applied to three-phase short circuit calculation, through the adoption of a node impedance method and a superposition theorem and based on the trend calculation result, a short circuit point current under a three-phase short circuit fault of an inner network, all node short circuit voltages and all branch circuit short circuit currents are calculated.
Owner:STATE GRID SICHUAN ECONOMIC RES INST +1
Commutation failure prediction method considering waveform distortion and DC current change
ActiveCN110718932AGuaranteed uptimeFormulated in timeAc-dc conversionElectric power transfer ac networkDc currentMathematical model
The invention provides a commutation failure prediction method considering waveform distortion and DC current change for an AC and DC interconnection system. The method comprises the following steps:establishing an AC-DC system commutation process mathematical model according to a DC commutation principle; decomposing three-phase components of a converter bus voltage based on discrete Fourier transform, and predicting a commutation voltage in a commutation process; predicting a direct current of the commutation process based on the superposition theorem; finally, predicting whether commutation failure occurs or not by comparing the extinction angle prediction value with the inherent limit extinction angle of a valve. The method can quickly predict the occurrence of commutation failure after a system fault, facilitates the timely making and taking of emergency control measures, and is of great significance to the maintenance of the stable operation of a power system.
Owner:SOUTHEAST UNIV +1
AC/DC hybrid micro-grid grid connection robust control method taking uncertainty into consideration
ActiveCN108521143ARealize flexible grid connectionImprove robustnessSingle network parallel feeding arrangementsCapacitanceOvercurrent
Provided is an AC / DC hybrid micro-grid grid connection robust control method taking uncertainty into consideration. The method includes the following steps: on the basis of the superposition theorem,establishing an AC / DC hybrid micro-grid grid connection mathematical model and a feed-forward system mathematical model in accordance with an AC / DC hybrid micro-grid grid connection topological structure; independently controlling a DC sub-micro-grid and providing a reference voltage to a filter capacitor in an AC / DC hybrid micro-grid; and constructing an AC / DC hybrid micro-grid grid connection robust controller and AC / DC hybrid micro-grid grid connection is achieved, so the robust performance of the AC / DC hybrid micro-grid is improved. The method of the invention avoids overcurrents in grid connection points during AC / DC hybrid micro-grid grid connection, realizes seamless switching, and enables AC / DC hybrid microgrids still to be normally connected in a condition of certain parameter perturbation.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING) +2
A power frequency magnetic field acquisition method based on the periphery of a high-voltage transmission line
PendingCN109902432AImprove the simulation effectImprove calculation accuracySpecial data processing applicationsCheck pointHigh pressure
The invention relates to a power frequency magnetic field obtaining method based on the periphery of a high-voltage transmission line. The method comprises the following steps of S10, simplifying an actual line to meet calculation of a power frequency magnetic field; S20, setting the positions and the number of simulated charges and matching points of the power transmission line; Step S30, establishing an equation set for solving the analog current by using the magnetic potential, setting a check point at a position, except the matching point, on the surface of the power transmission line, calculating the magnetic potential error of the check point by using the analog current, and if the requirement is not met, repeating the step S20 and recalculating the magnetic potential error; And S40,superposing the magnetic fields generated by the analog current by using a superposition theorem to obtain the magnetic induction intensity of any point in the field domain. Compared with the prior art, the method has the advantages of improving the calculation accuracy of the magnetic field around the high-voltage transmission line and the like.
Owner:SHANGHAI MUNICIPAL ELECTRIC POWER CO +1
Zero-dynamic DC output voltage control method and system of current source converter
ActiveCN111181428AImprove the quality of power supplyAchieve zero dynamic adjustmentAc-dc conversionAc network voltage adjustmentSource transformationSmall-signal model
The invention discloses a zero-dynamic DC output voltage control method and system of a current source converter. According to the invention, a power grid voltage feedforward control item and a DC side output current feedforward control item are effectively calculated through the instantaneous power theory, the small signal model analysis, the superposition theorem and other methods; the zero-dynamic DC output voltage control method of the current source converter is provided on such basis, and by adopting the DC output voltage and power grid voltage feedforward control technology, the methodcan realize stable DC output voltage, and can realize zero-dynamic adjustment of the output voltage under the condition that the power grid voltage fluctuates; furthermore, no matter under the condition of balanced drop or unbalanced drop of the power grid voltage, zero dynamic adjustment of the DC output voltage can be realized by adopting the method, the power supply quality of the current source converter is effectively improved, and the method is simple in implementation process and has a great practical engineering application value.
Owner:YANSHAN UNIV
A Calculation Method of High Frequency Harmonic Power Flow in Active Distribution Network
ActiveCN106655195BEasy to formulateAccurateAc networks with different sources same frequencyHarmonic controlVoltage source
The invention provides a calculation method for high-frequency harmonic power flow of an active power distribution network, aiming at the problems of how to calculate the high-frequency harmonic power flow of the active power distribution network, and no related calculation methods in the prior art. The calculation method comprises the steps of 1) obtaining a high-frequency harmonic impedance model of each component; 2) performing equivalence on high-frequency background harmonics and voltage source and current source type grid-connected inverters; 3) calculating harmonic voltages of to-be-calculated nodes of the active power distribution network during separate action after equivalence; and 4) obtaining the high-frequency harmonic power flow of the to-be-calculated nodes by utilizing a superposition theorem. According to the method, the high-frequency harmonic power flow of the active power distribution network is obtained by utilizing an equivalent high-frequency harmonic model of the active power distribution network and the superposition theorem in electrotechnics, so that high-frequency harmonic power flow distribution can be mastered more accurately and harmonic control measures can be better established for reducing harmonic control cost and influence on a power system; and therefore, the method has a very important effect for research and development of the active power distribution network.
Owner:ELECTRIC POWER RES INST OF STATE GRID ANHUI ELECTRIC POWER +3
Calculation method of equivalent three-phase short-circuit considering external network-to-ground branch and sensitivity information
ActiveCN107436995BHigh precisionAvoiding the problem of expanding the role of ground branchesInformaticsComplex mathematical operationsData packEngineering
The invention discloses an equivalent three-phase short circuit calculation method which considers an outer network ground branch circuit and sensitivity information. Firstly, whole-network basic data including system element parameters, a topology structure and a trend calculation result under a normal running condition is input, then based on a sensitivity consistency equivalent method, an equivalent network is constructed, through a sensitivity weighing method, ground branch circuit admittance parameters are deducted, and according to trend, sensitivity and power transfer characteristic consistency, other parameters are solved. Finally, an improved equivalent method is applied to three-phase short circuit calculation, through the adoption of a node impedance method and a superposition theorem and based on the trend calculation result, a short circuit point current under a three-phase short circuit fault of an inner network, all node short circuit voltages and all branch circuit short circuit currents are calculated.
Owner:STATE GRID SICHUAN ECONOMIC RES INST +1
Frequency response measurement system and method based on synchronous discrete Fourier transform
ActiveCN114019235AImprove efficiencySimple structureSpectral/fourier analysisNuclear energy generationSignal conditioning circuitsA d converter
Owner:ZHEJIANG UNIV
A grid-connected robust control method for AC/DC hybrid microgrid considering uncertainty
ActiveCN108521143BGrid connection is normalNo overcurrent phenomenonSingle network parallel feeding arrangementsCapacitanceMicrogrid
Provided is an AC / DC hybrid micro-grid grid connection robust control method taking uncertainty into consideration. The method includes the following steps: on the basis of the superposition theorem,establishing an AC / DC hybrid micro-grid grid connection mathematical model and a feed-forward system mathematical model in accordance with an AC / DC hybrid micro-grid grid connection topological structure; independently controlling a DC sub-micro-grid and providing a reference voltage to a filter capacitor in an AC / DC hybrid micro-grid; and constructing an AC / DC hybrid micro-grid grid connection robust controller and AC / DC hybrid micro-grid grid connection is achieved, so the robust performance of the AC / DC hybrid micro-grid is improved. The method of the invention avoids overcurrents in grid connection points during AC / DC hybrid micro-grid grid connection, realizes seamless switching, and enables AC / DC hybrid microgrids still to be normally connected in a condition of certain parameter perturbation.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING) +2
Performance Evaluation Method of Distance Protection in AC System Considering Hybrid DC Feed-in
ActiveCN106711972BSmooth connectionHigh precisionEmergency protective circuit arrangementsTransient stateElectric power system
The invention discloses an evaluation method for distance protection performance of a mixed direct current feeding alternating current system. The method comprises the following steps: utilizing the characteristics of a mixed multi-feed direct current transmission system to enable a conventional direct current transmission system and a flexible direct current transmission system before the fault to be equivalent to a constant current source; enabling the conventional direct current transmission system and the flexible direct current transmission system after the fault to be equivalent to a controlled current source; subtracting the constant current source in a network before the fault from the controlled current source in the network under a normal condition after the fault equivalent to the conventional direct current transmission system and the flexible direct current transmission system in a fault component network; and adopting a transient state principle for acquiring a short circuit current at a fault point, thereby utilizing a superposition theorem to acquire the variation of voltage and current on a protecting mounting position in the fault component network, further acquiring the measured impedance and verifying the protection sensitivity. The defects of an evaluation scheme for the distance protection performance characteristics in a mixed multi-feed direct current transmission system model and an alternating current system connected with the mixed multi-feed direct current transmission system model in a traditional electrical power system equivalent model can be overcome.
Owner:国家电网有限公司西南分部 +1
Method for predicting electrical properties of deformed log-periodic antennae based on electromechanical coupling model
InactiveCN102253290BAccurate analysisRealize the structureElectrical testingAntenna designElement model
The invention discloses a method for predicting electrical properties of deformed log-periodic antennae based on an electromechanical coupling model, aiming to mainly solve the problem of electromechanical separation in the log-periodic antennae. The method comprises the following steps: building a finite element model based on the structural design parameters of the log-periodic antennae, loading dead load, random wind and other environmental loads and carrying out finite element analysis to obtain the structure displacement field of the log-periodic antennae; utilizing the analysis results to obtain current distribution of oscillator units in the log-periodic antennae and phase difference caused by the positions and deflection of the oscillator units and computing the far field patternsof the log-periodic antennae according to the superposition theorem; and obtaining the electrical property parameters of the log-periodic antennae to realize electromechanical coupling analysis of the log-periodic antennae. The method can help the log-periodic antenna structural design personnel improve the antenna design and manufacturing quality.
Owner:王从思
Method for estimating single particle crosstalk among multiple lines
ActiveCN110752863AShort computing timeChannel estimationLine-transmissionCrosstalk measurementSoftware engineering
The invention discloses a method for estimating single particle crosstalk among multiple lines, which belongs to the technical field of crosstalk measurement and comprises the following steps of: 1, determining lumped RC coupling interconnection line model parameters; 2, constructing a single particle crosstalk equivalent circuit; 3, calculating the response voltage of the disturbed line under theindependent action of each disturbed line; 4, establishing a disturbed line comprehensive single particle crosstalk estimation model; and step 5, determining crosstalk peak voltage and pulse width. According to the invention, the admittance rule is defined; the SET equivalent circuit, the voltage basic law, the substitution theorem and the superposition theorem are utilized to establish the method for estimating the single-particle crosstalk between the multiple lines, the analytical expression of the peak voltage and the pulse width of the single-particle crosstalk is given through derivation operation and Taylor formula expansion, and the waveform and the noise peak of the single-particle crosstalk between the multiple lines can be accurately estimated.
Owner:AIR FORCE ENG UNIV OF PLA AIRCRAFT MAINTENACE MANAGEMENT SERGEANT SCHOOL
Processing method for converting fault records into harmonics
InactiveCN102323979ASimple processing methodSimple structure and processSpecial data processing applicationsAc network circuit arrangementsHarmonicLinear circuit
The invention discloses a processing method for converting fault records into harmonics. The method comprises the following steps of: decomposing a periodic non-sinusoidal signal into a series of sinusoidal components with different frequencies; superposing the components according to a superposition theorem of a linear circuit to get response under excitation of the periodic non-sinusoidal signal; decomposing the non-sinusoidal excitation into a series of sinusoidal quantities with different frequencies; displaying the oscillographs of all harmonics, and additionally displaying the content of all harmonics in a list; and displaying a harmonics histogram at a certain time, and storing the harmonics histogram in an excel through data output. The processing method for the fault records is simple and intuitive, speedy in analysis and simple in structure flows.
Owner:深圳市康必达中创科技有限公司
Method for calculating short-circuit current of multiphase power distribution network containing negative-sequence current injection IIDG
PendingCN114597948AAchieve decouplingRealize short-circuit current calculationSingle network parallel feeding arrangementsPolyphase network asymmetry elimination/reductionControl theoryDistribution grid
The invention provides a short-circuit current calculation method for a multiphase power distribution network containing a negative sequence current injection IIDG, and the method comprises the steps: building an IIDG sequence component equivalent model through analyzing the relation between the IIDG fault current and an employed control strategy; a sequence equivalent model of the unbalanced multiphase power distribution network is established by adopting a method of introducing a virtual node, a virtual line and a compensation current; a sequence node voltage equation of the multi-phase power distribution network containing the IIDG is constructed, the relation between the IIDG output current and the corresponding node voltage and the relation between the decoupling compensation current and the corresponding node voltage are revealed, and an iterative correction short-circuit current calculation method based on the superposition theorem is provided. According to the method, the feasibility and effectiveness of the calculation method are verified through simulation comparison, the calculation speed is obviously improved, and meanwhile the convergence speed of iteration errors is higher.
Owner:YUNNAN MINZU UNIV
A Finite Array Antenna Analysis Method
ActiveCN106257465BAvoid calculationSmall amount of calculationDesign optimisation/simulationComplex mathematical operationsComputational problemFull wave
The invention discloses a finite array antenna analysis method. The method includes the following steps that the subarray solving scale is determined according to solving precision; full-wave solving is carried out on determined subarrays with a moment method; medium and large arrays are extrapolated according to the subarray solving result; in the process of solving subarray radiation fields, the subarray radiation fields are assumed to be radiation far fields, and an array antenna pattern is obtained. According to the method, based on the local effect of array antenna unit radiation fields and the electromagnetic field superposition principle, the numerical simulation issue of medium and large array antennas is simplified into full-wave solving of the subarrays according to the solving precision, then all unit radiation fields in the large arrays are equivalent to the unit radiation fields at corresponding positions in the subarrays, and finally based on the superposition theorem, the total radiation field is calculated, so that full-array matrix filling and the operation of solving the system of linear equations in the calculation process are omitted; besides, the radiation field calculation issue of the large arrays is transformed into the unit radiation field calculation issue of the small arrays, so that the calculation amount is effectively reduced, and the implementation difficulty is lowered.
Owner:CHINA SHIP DEV & DESIGN CENT
The Method of Suppressing Transient DC Bias of Three-Port Isolated DC/DC Converter
ActiveCN110149053BSolve safe operationIssues Affecting Safe OperationDc-dc conversionElectric variable regulationMathematical modelPhase angle
The invention discloses a method for suppressing the transient DC bias of a three-port isolated DC / DC converter, first analyzing the formation mechanism of the TAB transient DC bias under traditional phase-shift control, and determining the formation of the TAB transient DC bias Reason; based on the formation reason, establish its DC bias suppression mathematical model; determine the driving signal combination method that satisfies the DC bias suppression mathematical model, and suppress the transient DC bias. To establish the mathematical model of DC bias suppression, first determine the equivalent circuit of TAB when the voltage of each port acts alone according to the Y-type equivalent circuit of TAB, and then obtain the current expression of each port of TAB by the superposition theorem, assuming that the unit switching period when the phase shift angle changes The volt-second product of the positive and negative amplitudes of the square wave voltages at ports 2 and 3 is zero, and the inductance can still achieve volt-second balance. The current relationship before and after the phase shift angle is obtained, and then the TAB DC bias suppression mathematical model is obtained. . The problem that the transient DC bias affects the safe operation of TAB is solved.
Owner:HUNAN UNIV
Method for calculating short-circuit current of doubly-fed wind turbine generator
PendingCN114647920AImprove accuracyDesign optimisation/simulationSpecial data processing applicationsTerminal voltageTotal current
The invention discloses a method for calculating short-circuit current of a doubly-fed induction generator in the technical field of wind power generation systems, which comprises the following steps of: establishing a fault equivalent network considering rotor converter control by considering transient regulation and control of a bilateral converter, and respectively deducing a DFIG short-circuit current calculation method when a Crowbar is not accessed and when the Crowbar is accessed. The short-circuit current calculation method comprises the following steps: acquiring the generator terminal voltage drop depth of the doubly-fed fan and unit operation parameters after a fault occurs, establishing a doubly-fed fan fault equivalent network considering the transient regulation and control influence of a rotor converter, calculating stator and rotor short-circuit current in the fault equivalent network, deducing a stator short-circuit current double-frequency component analytic expression, and calculating the fault equivalent network of the doubly-fed fan. And according to the superposition theorem, obtaining a stator and rotor short-circuit total current expression when the Crowbar is not accessed. And then the short-circuit current of the doubly-fed wind turbine generator under the Crowbar access condition is calculated. According to the method, the DFIG short-circuit current when the Crowbar is not accessed and the DFIG short-circuit current after the Crowbar is accessed can be accurately calculated.
Owner:国网山西省电力公司经济技术研究院
Modeling method of oplc thermal circuit model based on superposition principle
InactiveCN108153940BImprove reliabilityImprove rationalityDesign optimisation/simulationSpecial data processing applicationsEngineeringParticle swarm algorithm
The invention relates to an OPLC thermal circuit model modeling method based on the superposition principle, which belongs to the technical field of power cable detection. The steps of the present invention are: using COMSOL software to realize the simulation of the temperature field of OPLC; establishing the thermal circuit model of OPLC four-core heating and single-core heating, and establishing the thermal circuit model of OPLC three-core heating according to the superposition theorem; adopting particle swarm The algorithm identifies the parameters of the OPLC thermal path model when the three cores are heating; according to the identification results, the OPLC optical fiber position thermal path model is established. The present invention applies the principle of superposition to superimpose the heat path models under the two different conditions of OPLC four-cable core heating and single-cable core heating to obtain a more accurate thermal path model under the condition of OPLC three-cable core heating, which effectively improves the The rationality of OPLC thermal circuit model establishment. Using the particle swarm algorithm to identify the parameters in the thermal circuit model, the model parameters are optimized, and the accuracy of the temperature calculation values of each layer inside the OPLC is effectively improved. Engineering applications are of great significance.
Owner:NORTHEAST DIANLI UNIVERSITY +2
Multi-frequency oscillation out-of-step oscillation center location and migration tracking system and method
ActiveCN107611996BAchieve positioningVerify correctnessPower oscillations reduction/preventionVoltage vectorElectric power system
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)
A zero dynamic DC output voltage control method and system for a current source converter
ActiveCN111181428BImprove the quality of power supplyAchieve zero dynamic adjustmentAc-dc conversionAc network voltage adjustmentSource transformationControl theory
The invention discloses a zero dynamic DC output voltage control method and system of a current source converter. The present invention effectively calculates the power grid voltage feedforward control item and the DC side output current feedforward control item through methods such as instantaneous power theory, small signal model analysis, and superposition theorem, and proposes a zero dynamic DC output of a current source converter based on this Voltage control method, the method adopts DC output voltage and grid voltage feed-forward control technology, not only can realize stable DC output voltage, but also can realize zero dynamic adjustment of output voltage in the case of grid voltage fluctuation; further, no matter in When the grid voltage falls in balance or unbalanced, adopting the method of the present invention can realize zero dynamic adjustment of the DC output voltage, effectively improving the power supply quality of the current source converter, and the method is simple in implementation process and has great advantages. Practical engineering application value.
Owner:YANSHAN UNIV
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