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31 results about "P v curve" patented technology
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Multi-step size based photovoltaic power generation system maximum power tracking control method
ActiveCN104298295AHigh speedHigh stability and precisionPhotovoltaic energy generationElectric variable regulationCells panelP v curve
The invention discloses a multi-step size based photovoltaic power generation system maximum power tracking control method. The multi-step size based photovoltaic power generation system maximum power tracking control method comprises the steps of firstly setting an initial disturbance step size; utilizing a function M=V*abs (dP / dV) to conduct demarcation on a photovoltaic cell P-V curve, taking step size d1 in a left-side region of a maximum power point when a value of a function dM / dV is greater than 0; taking step size d1*M / P when the value of the function dM / dV is smaller than 0; taking step size d2 in a right-side region of the maximum power point when a value of the function M is greater than power P; taking step size d2*M / P when the value of the function is smaller than the power P; The multi-step size based photovoltaic power generation system maximum power tracking control method is simple and practical, and the proportional relation of an initial fixed step size can be determined by utilizing photovoltaic cell panel parameters provided by a manufacturer. The problem that steady accuracy and dynamic tracking speed cannot be simultaneously considered in most of maximum power tracking controls is solved by means of the method.
Owner:SOUTH CHINA UNIV OF TECH +1
Maximum power tracking capture photovoltaic control method with self-adaptive search algorithm
InactiveCN101078942AFast track work in real timeTrack workPhotovoltaic energy generationAdaptive controlEngineeringSolar battery
The invention discloses a maximal power tracing and catching photovoltaic controlled method with self-adaptive searching algorithm, which comprises the following steps: setting initial step-length; monitoring the voltage and the current of the i time solar battery array; evaluating the i time power; getting voltage change quantity delta Ui and power change delta Pi of the i time and the i-1 time; judging whether the delta Ui is 0; backing to sample if delta Ui=0; evaluating slope delta Pi / delta Ui of P-V curve if delta Ui is not equal to 0; judging whether delta Pi / delta Ui absolute value is not less than the setting accuracy E; un-changing dutycycle of buck circuit switching tube if |delta Pi / delta Vi|=E. This invention does not need device to test light intensity and temperature, which can decrease the cost of solar electric power generation system.
Owner:SOUTH CHINA UNIV OF TECH
Method for obtaining uniaxial stress-strain relation of material through small punch test
ActiveCN106124293AQuantitative evaluation of degradation performanceTo overcome the shortcomings such as large size restrictionsStrength propertiesSmall sampleMaterials testing
The invention discloses a method for obtaining uniaxial stress-strain relation of a material through a small punch test. After a continuous load-displacement curve of a stamped wafer sample is obtained, power-law fitting is conducted on the stage III of the P-V curve, obtained load characteristics and displacement indexes are introduced to a Hollomon equation so as to obtain the uniaxial stress-strain relation of the material. The method is suitable for ductile and power-law isotropic hardening materials, the uniaxial stress-strain relation of the material can be obtained only by cutting out a small wafer sample from an existing member in special circumstances such as high temperature and irradiation, and accordingly the degradation properties of the material are assessed. The method has weaker destructiveness on the existing member, achieves the micro-damage detection, sample processing and testing principles are simpler, obtained results have higher accuracy, the shortcoming that a traditional uniaxial drawing test is largely limited by material size and the like is overcome, and the cost lower. The method has the greater advantages in testing of precious-metal servicing micro-force materials establishing constitutive relation of minimally invasive wafers and other small samples.
Owner:SOUTHWEST JIAOTONG UNIV
Fault detection system and method suitable for photovoltaic array
InactiveCN109004903ARapid positioningEasy maintenancePhotovoltaic monitoringSingle network parallel feeding arrangementsV curveP v curve
The invention discloses a fault detection system and method suitable for a photovoltaic array, and relates to the technical field of photovoltaic fault detection. The method comprises the following steps: calculating the maximum output power of a photovoltaic array under the simulation condition, and simultaneously recording the current value and the voltage value when the maximum output power isobtained; measuring the I-V characteristic, and after measurement of many times, obtaining a short-circuit current value, open-circuit voltage and a P-V curve peak value number of the photovoltaic array from an I-V curve; comparing the theoretical output power in simulation with the actual output power, and judging the mode of the photovoltaic array by an area where the ratio of the theoretical output power and the actual output power is; If the photovoltaic array is judged to be faulty, further judging the fault type, and using a threshold value method to isolate the faults with different attributes; and distinguishing two sets of faults with the same attribute by an extendable network model. The method can not only discover the fault on line when the photovoltaic array fails, but can also quickly locate the fault type.
Owner:CHINA JILIANG UNIV
Test method for uniaxial constitutive relation of ductile material
ActiveCN106644711AThe method is simpleWide range of constitutive relationsMaterial strength using tensile/compressive forcesP v curveStressed state
The invention discloses a method for determining the large deformation uniaxial constitutive relation of a material based on the energy principle and a P-V curve obtained by stretching a central circular hole plate specimen. The method comprises the following steps: performing quasi-static tensile test on a central circular hole plate specimen to obtain a continuous P-V curve, and determining the elastic stiffness S, the feature load P* and the displacement index m by the curve so as to obtain the large deformation uniaxial constitutive relation of the material. The method disclosed by the invention is applicable to a ductile material with an isotropic strengthening and constitutive relation according with the power law, wherein the structure of the central circular hole plate specimen is special, namely during the tensile test, the circular hole edge center point material unit of the specimen is under uniaxial stress state before the occurrence of necking; compared with an equidistant specimen, the method disclosed by the invention is easier to implement, and the obtained uniaxial stress-strain relation is wider in range; the method has great significance on the engineering structure design and safety assessment work.
Owner:SOUTHWEST JIAOTONG UNIV
Area information based quiescent voltage unstability prediction method
ActiveCN101819243ASafe and stable operationPrevent crashCurrent/voltage measurementFault locationElectric power systemData acquisition
The invention belongs to the field of a power supply system and automatics thereof and is applicable to wide area information based quiescent voltage unstability prediction of power grid real-time states and working conditions after a predicted accident. The method comprises the steps of: (1) integrating the PMU (Power Management Unit) node distribution information and actual grid structure of the power grid and dividing the power grid into a plurality of generating areas and load areas; (2) carrying out P-V curve computation on the basis of SCADA (Supervisory Control And Data Acquisition) measurement information and state estimation results to obtain critical voltage of each node at the moment of voltage breakdown; (3) carrying out Q-V model analysis computation on a trend the voltage ofwhich is close to breakdown to obtain all participation factors installed with PMU nodes; (4) weighting the voltage margin of each node in real time to be used as a compressive voltage margin index according to real voltage data detected by a PMU by taking the PMU node participation factors as weight; and (5) when the compressive voltage margin index is relatively small, using the sensitivity of the reactive power loss change of a receiving section in a load area to transmission active power as a real-time proof for calculating voltage unstability.
Owner:NARI TECH CO LTD +1
Photovoltaic charger control device and method
InactiveCN104377762AImplement soft handoverAvoid Stuck SituationsDifferent batteries chargingElectric powerV curveP v curve
The invention relates to a photovoltaic charger control device which comprises a photovoltaic voltage sampling unit, an output current sampling unit, an output voltage sampling unit, an MPPT unit, a first voltage controller, a voltage stabilizing control given unit, a second voltage controller, an amplitude limiting control unit, a current controller and a PWM generator. A photovoltaic charger control method comprises the steps that an MPPT control ring, a voltage stabilizing control ring, two voltage inner rings and a current control outer ring are adopted, the MPPT control ring output minimum value and the voltage stabilizing control ring output minimum value are selected as the given Iref of the current control outer ring, the output current value Ibuck of a photovoltaic charger is used as the feedback of the current control outer ring, the current control outer ring outputs the driving duty ratio to the PWM generator, and the PWM generator generates PWM driving signals to drive a switch tube of a main circuit of the photovoltaic charger to work. According to the photovoltaic charger control device and method, it is ensured that the photovoltaic voltage is always on the right side of a polar plate P-V curve, no output current jumping occurs, and it is ensured that photovoltaic energy is used more efficiently.
Owner:XIAMEN KECAN INFORMATION TECH
Method for measuring wind fire bundling configuration proportion on basis of power circle
InactiveCN103078352ASafe and stable operationSolve the problem of the configuration ratio of wind and fire bundlingSingle network parallel feeding arrangementsWind energy generationElectric power systemP v curve
The invention discloses a method for measuring a wind fire bundling configuration proportion on the basis of a power circle, which comprises the following steps of: a step 10 of setting initial parameters; a step 20 of generating an operation mode according to the wind fire bundling configuration proportion; a step 30 of making a P-V curve according to a load flow calculation result obtained in the step 20, and measuring a static voltage stability margin value of a power system according to a P-V curve method; a step 40 of determining relevant parameters of a wind power station and a thermal power plant; a step 50 of measuring the optimal wind fire bundling configuration proportion of the iteration according to a power circle principle; and a step 60 of measuring the optimal wind fire bundling configuration proportion. According to the measuring method, the optimal wind fire bundling configuration proportion of the power system in the static voltage stability margin can be measured, so that the problem of the wind fire configuration proportion is solved.
Owner:SOUTHEAST UNIV
Three-phrase power-distributing network continuation power flow analysis of distributed power supply
ActiveCN104734148AAvoid divergenceThe operating state is close to the real situationSpecial data processing applicationsInformaticsDistribution power systemEngineering
The invention discloses a three-phrase power-distributing network continuation power flow analysis of the distributed power supply, and belongs to the technical field of electrical power system static voltage stability analysis. According to the three-phrase power-distributing network continuation power flow analysis, by the introducing of the increasing relation between the active power output of load parameter simulation distributed power supply and the load power, a three-phrase power-distributing network continuation power flow equation with the load parameter is established, and a P-V curve of the three-phrase power-distributing network is traced with the method of prediction-parameterization-method correction. The invention also provides an identification method of branch-point type when the distributed power supply is connected. The grid-connected injection current spillage of the distributed power supply in the continuation power flow analyzing process is considered, a node-type bilateral switching logic is adopted to conduct the process, and the running state of the distributed power supply is more close to a real situation, so that the P-V curve of the three-phrase power-distributing network can be traced accurately, the voltage collapse critical point can be calculated accurately, and the branch-point type can be identified accurately.
Owner:HOHAI UNIV
Photovoltaic inverter two-peak dynamic/static MPP tracking efficiency test method
ActiveCN104362977AFind the maximum power pointTo achieve the purpose of follow-up testingPhotovoltaic monitoringPhotovoltaic energy generationTest efficiencyV curve
The invention provides a photovoltaic inverter two-peak dynamic / static MPP tracking efficiency test method. The method includes the following steps that the maximum power point reached by photovoltaic arrays on the direct current side and the voltage range of an MPP of a photovoltaic inverter are determined; the photovoltaic arrays are selected and matched with the photovoltaic inverter; a single peak P-V curve of the photovoltaic arrays is determined; a two-peak MPP test efficiency P-V curve of the photovoltaic arrays is set and a photovoltaic inverter two-peak dynamic / static MPP tracking efficiency test is finished. According to the method, two-peak I-V curves of a direct current source under different powers and different blocking degrees are edited, the capability of the photovoltaic inverter for tracking the maximum power point of the two-peak I-V curves is tested and evaluated, and the gap in the aspect of tests and evaluation of two-peak I-V curve MPP tracking efficiency in the prior art is filled in.
Owner:STATE GRID CORP OF CHINA +2
Fixed photovoltaic array connection optimization based on BIM
PendingCN108197371AShort payback periodGeometric CADDesign optimisation/simulationModel selectionP v curve
The invention provides a connection optimization scheme for a roof photovoltaic system based on a building information model (BIM). According to the scheme, digital modeling is performed on a building, a solar annual motion model is established, and the exposure dose of a fixed photovoltaic component is acquired; modeling simulation is performed on a cell model and a photovoltaic array hardware circuit, corresponding exposure dose data is allocated to each photovoltaic module, an output characteristic P-V curve of an array is acquired, and the generating capacity of the photovoltaic componentis calculated; the generating capacity, inverter model selection, roof cost, roof photovoltaic array cost and other factors of different connection schemes are comprehensively considered, and an optimization objective function is established; and a globally optimal solution of the objective function is solved, an optimal connection scheme and inverter type are acquired, and automatic connection ofthe photovoltaic array is realized in the BIM. Through the scheme, by selecting an appropriate photovoltaic array connection mode, the photovoltaic investment return period can be obviously shortened, and the effect of optimizing the roof photovoltaic system is achieved.
Owner:CENT SOUTH UNIV
Novel MPPT algorithm and method for obtaining hardware for novel MPPT algorithm
ActiveCN104378059AFind exactlyFind quicklyPhotovoltaicsPhotovoltaic energy generationMppt algorithmEngineering
The invention discloses a novel MPPT algorithm and a method for obtaining hardware for the novel MPPT algorithm. The novel MPPT algorithm comprises the steps that the open-circuit voltage of a solar cell panel and the battery voltage at present are sampled and measured; when the open-circuit voltage of the solar cell panel is higher than the battery voltage, tracking is started, and a master control unit outputs PSMC1A, PSMC1B and PSMC2A; the PSMC1A outputs PWM1 through an AND logic circuit, and the PSMC1B and PSMC2A output PWM2 through the AND logic circuit; the PWM1 and the PWM2 output PWMH and PWML respectively through a driving circuit unit; a synchronous rectification unit is driven by the PWMH and the PWML to scan the P-V curve of the solar cell panel, and the maximum power point of the solar cell panel is obtained by sampling output current in real time through a comparison current sampling unit. According to the novel MPPT algorithm and the method for obtaining the hardware for the novel MPPT algorithm, the maximum power point of the solar cell panel can be found accurately and rapidly, limitation of the environmental factors such as illumination, temperature and shadow shading is avoided, the tracking speed is high, and the efficiency is high.
Owner:深圳硕日新能源科技有限公司
Maximum power tracking capture photovoltaic control method with self-adaptive search algorithm
InactiveCN100498636CFast track work in real timeLow costPhotovoltaic energy generationAdaptive controlSolar batteryMaximum power point tracking
The invention discloses a maximal power tracing and catching photovoltaic controlled method with self-adaptive searching algorithm, which comprises the following steps: setting initial step-length; monitoring the voltage and the current of the i time solar battery array; evaluating the i time power; getting voltage change quantity delta Ui and power change delta Pi of the i time and the i-1 time; judging whether the delta Ui is 0; backing to sample if delta Ui=0; evaluating slope delta Pi / delta Ui of P-V curve if delta Ui is not equal to 0; judging whether delta Pi / delta Ui absolute value is not less than the setting accuracy E; un-changing dutycycle of buck circuit switching tube if |delta Pi / delta Vi|=E. This invention does not need device to test light intensity and temperature, which can decrease the cost of solar electric power generation system.
Owner:SOUTH CHINA UNIV OF TECH
Voltage collapse point calculation method comprising wind power random fuzzy injection power system fluctuation
The invention discloses a voltage collapse point calculation method comprising wind power random fuzzy injection power system fluctuation, and relates to the field of a power system. In a wind power output random fuzzy injection power system, dancing system P-V feature curves are solved according to continuous trends, a voltage collapse point of each P-V curve is found, probability distribution which voltage values Vcr and lambda values at the collapse points obey are respectively fitted; then membership functions of probability distribution function parameters are respectively found through multiple fitting, random fuzzy features of the voltage collapse points are described by use of opportunity measurement, and uncertainty descriptions for positions of fluctuated voltage collapse points are obtained. The method provided by the invention can provide a new thinking approach for later calculation of a power system static-state safety domain, provides a base for calculation of a power system safety domain more according with actual wind power injection and represents an important reference for power scheduling personnel in safe and stable operation of the power system.
Owner:CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
Error correction method for dynamic MPPT (maximum power point tracking) efficiency test on photovoltaic inverter
InactiveCN104953948ATest fineTest accuratePhotovoltaic monitoringPhotovoltaic energy generationV curveP v curve
The invention provides an error correction method for a MPPT (maximum power point tracking) efficiency test on a photovoltaic inverter. The method comprises steps as follows: selecting a P-V curve model output by a photovoltaic simulator under an STC condition according to the capacity of the to-be-tested photovoltaic inverter and the type of a matched assembly; on the basis of the P-V curve model, acquiring an I-V curve output by a photovoltaic array simulator during change of irradiance according to the relation among open-circuit voltage UOC;STC, short-circuit current ISC;STC and irradiance G; acquiring an I-V curve output by the photovoltaic array simulator according to the requirement of the EN50530 standard for dynamic MPPT test irradiance; constructing a dynamic MPPT efficiency test platform for the photovoltaic inverter, acquiring test data of the I-V curve output by the photovoltaic array simulator, and uploading the data to an upper computer; correcting errors by the upper computer. Thus, the fine and accurate test on the dynamic MPPT efficiency of the photovoltaic inverter is realized.
Owner:CHINA ELECTRIC POWER RES INST +3
Device for testing breaking tenacity in long and narrow space and using method of device
ActiveCN107314937ARealize the measurementReduce volumeMaterial strength using tensile/compressive forcesP v curveEngineering
The invention discloses a device for testing breaking tenacity in a long and narrow space and a using method of the device. The device comprises a sleeve, a left clamping head, a right clamping head, a sliding block and pusher fixing rods, the left clamping head, the right clamping head and a tensile sample are mounted inside the sleeve, a functional window used for mounting of the tensile sample and a displacement sensor is arranged in a sidewall of the sleeve, the tensile sample is connected with the left clamping head and the right clamping head through pin bolts, the left clamping head and the right clamping head are connected with the sleeve and the sliding block through mutually-fitted blocking heads and blocking grooves, the sliding block is connected with a force sensor through a bolt, the other end of the sliding block is connected with a matched electric drive pusher, a target card is mounted on the left clamping head and used for providing positioning signals for the displacement sensor. The device has the advantages that by tensioning a test piece and reading values of the displacement sensor and the force sensor, a force-breaking opening displacement (P-V curve) can be drawn to calculate the breaking tenacity of the test piece; a problem in measurement of breaking opening displacement amount in the long and narrow space is solved, and experimental requirements like breaking tenacity measurement in a high-intensity magnetic field condition can be satisfied.
Owner:XI AN JIAOTONG UNIV
Area information based quiescent voltage unstability prediction method
ActiveCN101819243BSafe and stable operationPrevent crashCurrent/voltage measurementFault locationNODALWide area
The invention belongs to the field of a power supply system and automatics thereof and is applicable to wide area information based quiescent voltage unstability prediction of power grid real-time states and working conditions after a predicted accident. The method comprises the steps of: (1) integrating the PMU (Power Management Unit) node distribution information and actual grid structure of the power grid and dividing the power grid into a plurality of generating areas and load areas; (2) carrying out P-V curve computation on the basis of SCADA (Supervisory Control And Data Acquisition) measurement information and state estimation results to obtain critical voltage of each node at the moment of voltage breakdown; (3) carrying out Q-V model analysis computation on a trend the voltage ofwhich is close to breakdown to obtain all participation factors installed with PMU nodes; (4) weighting the voltage margin of each node in real time to be used as a compressive voltage margin index according to real voltage data detected by a PMU by taking the PMU node participation factors as weight; and (5) when the compressive voltage margin index is relatively small, using the sensitivity of the reactive power loss change of a receiving section in a load area to transmission active power as a real-time proof for calculating voltage unstability.
Owner:NARI TECH CO LTD +1
Method and system for realizing stabilized monitoring of static voltage in electric power system
The invention relates to a method and a system for realizing stabilized monitoring of a static voltage in an electric power system. The method comprises the steps of: constructing power flow equations corresponding to a power flow method, and solving an initial transition running state of the system according to the power flow equations; detecting whether the solved initial transition running state meets a preset switching condition, if yes, constructing expanded power flow equations corresponding to a continuous power flow method based on the current running state of the system, and solving a system stable transition running state of the system according to the expanded power flow equations; and generating a system P-V curve according to the solved initial transition running state and stable transition running state, and further obtaining a stable power limit value of the static voltage and voltage critical value information when the load of the electric power system changes. According to the invention, the generation speed of the P-V curve us increased, the generation precision of the P-V curve is ensured, and the stable power limit value of the static voltage and the voltage critical value information when the load of the electric power system changes are obtained rapidly and accurately.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
Pressuremeter test method considering temperature effect
ActiveCN109881656AReduce the impact of in situ testingReduced test impactIn situ soil foundationP v curveEngineering
The invention relates to a pressuremeter test method considering a temperature effect. A pressuremeter and a cylinder are used, and the cylinder has a heating function. According to the design key points, the pressuremeter test method comprises the steps that first, a heating wire of the cylinder starts to heat, and after the cylinder reaches a predetermined temperature, the cylinder is pressed into soil on site; second, after the cylinder is pressed into a soil body, the soil body is continuously heated for a period of time; third, a hole is drilled in the center of the cylinder, a pressuremeter device of the pressuremeter is then placed into the hole, and the temperature T of the test soil is measured through a temperature sensor; and fourth, a pressuremeter loading test is carried out to obtain a P-V curve. By adopting the pressuremeter test method, the pressuremeter test of soil bodies at different temperatures can be carried out to meet the requirements of scientific research andengineering.
Owner:WENZHOU UNIVERSITY
Voltage stability evaluation method for integrated transmission and distribution network based on distributed computing
ActiveCN105048468BEnsure consistencyGuaranteed synchronicityResourcesAc networks with different sources same frequencyElectric power transmissionEngineering
Owner:HOHAI UNIV
A photovoltaic charger control device and control method
InactiveCN104377762BImplement soft handoverAvoid Stuck SituationsDifferent batteries chargingElectric powerV curveP v curve
The invention relates to a photovoltaic charger control device which comprises a photovoltaic voltage sampling unit, an output current sampling unit, an output voltage sampling unit, an MPPT unit, a first voltage controller, a voltage stabilizing control given unit, a second voltage controller, an amplitude limiting control unit, a current controller and a PWM generator. A photovoltaic charger control method comprises the steps that an MPPT control ring, a voltage stabilizing control ring, two voltage inner rings and a current control outer ring are adopted, the MPPT control ring output minimum value and the voltage stabilizing control ring output minimum value are selected as the given Iref of the current control outer ring, the output current value Ibuck of a photovoltaic charger is used as the feedback of the current control outer ring, the current control outer ring outputs the driving duty ratio to the PWM generator, and the PWM generator generates PWM driving signals to drive a switch tube of a main circuit of the photovoltaic charger to work. According to the photovoltaic charger control device and method, it is ensured that the photovoltaic voltage is always on the right side of a polar plate P-V curve, no output current jumping occurs, and it is ensured that photovoltaic energy is used more efficiently.
Owner:XIAMEN KECAN INFORMATION TECH
A test method for uniaxial constitutive relation of ductile materials
ActiveCN106644711BSimple methodWide range of constitutive relationsMaterial strength using tensile/compressive forcesEnergy basedP v curve
Owner:SOUTHWEST JIAOTONG UNIV
A kind of mppt algorithm and its hardware structure
ActiveCN104378059BFind exactlyFind quicklyPhotovoltaicsPhotovoltaic energy generationHardware structureMppt algorithm
The invention discloses a novel MPPT algorithm and a method for obtaining hardware for the novel MPPT algorithm. The novel MPPT algorithm comprises the steps that the open-circuit voltage of a solar cell panel and the battery voltage at present are sampled and measured; when the open-circuit voltage of the solar cell panel is higher than the battery voltage, tracking is started, and a master control unit outputs PSMC1A, PSMC1B and PSMC2A; the PSMC1A outputs PWM1 through an AND logic circuit, and the PSMC1B and PSMC2A output PWM2 through the AND logic circuit; the PWM1 and the PWM2 output PWMH and PWML respectively through a driving circuit unit; a synchronous rectification unit is driven by the PWMH and the PWML to scan the P-V curve of the solar cell panel, and the maximum power point of the solar cell panel is obtained by sampling output current in real time through a comparison current sampling unit. According to the novel MPPT algorithm and the method for obtaining the hardware for the novel MPPT algorithm, the maximum power point of the solar cell panel can be found accurately and rapidly, limitation of the environmental factors such as illumination, temperature and shadow shading is avoided, the tracking speed is high, and the efficiency is high.
Owner:深圳硕日新能源科技有限公司
Overheat protection device and method of inverter
ActiveCN102710112BAvoid large fluctuations in output powerExtend grid-connected power generation timeEmergency protective circuit arrangementsPower conversion systemsV curveP v curve
The invention relates to an overheat protection device and method of an inverter. The overheat protection method comprises the following steps of: detecting real-time temperature of a power device of the inverter in the operation process; judging whether the real-time temperature is greater than a first preset temperature; and if so, boosting the maximum power tracking output voltage to the right side of a maximum power point of a P-V curve, carrying out amplitude-limiting on active current giving and reducing the active current giving, wherein the output power of the inverter is reduced by reduction of the active current giving so that the temperature of the power device is reduced. When a first judgment module judge that the real-time temperature is less than the first preset temperature, the detection module continues detect. The overheat protection device and method disclosed by the invention have the advantages of capabilities of carrying out rapid control on the temperature in real time, avoiding larger fluctuation of the output power of the inverter, controlling the output power of the inverter to be zero without poweroff and effectively prolonging the grid-connected generation time of the inverter.
Owner:SUNGROW POWER SUPPLY CO LTD
A photovoltaic inverter bimodal dynamic/static MPP tracking efficiency test method
ActiveCN104362977BTo achieve the purpose of follow-up testingAchieve the purpose of dynamic bimodal MPPT efficiency testPhotovoltaic monitoringPhotovoltaic energy generationTest efficiencyV curve
The invention provides a photovoltaic inverter two-peak dynamic / static MPP tracking efficiency test method. The method includes the following steps that the maximum power point reached by photovoltaic arrays on the direct current side and the voltage range of an MPP of a photovoltaic inverter are determined; the photovoltaic arrays are selected and matched with the photovoltaic inverter; a single peak P-V curve of the photovoltaic arrays is determined; a two-peak MPP test efficiency P-V curve of the photovoltaic arrays is set and a photovoltaic inverter two-peak dynamic / static MPP tracking efficiency test is finished. According to the method, two-peak I-V curves of a direct current source under different powers and different blocking degrees are edited, the capability of the photovoltaic inverter for tracking the maximum power point of the two-peak I-V curves is tested and evaluated, and the gap in the aspect of tests and evaluation of two-peak I-V curve MPP tracking efficiency in the prior art is filled in.
Owner:STATE GRID CORP OF CHINA +2
Continuous Power Flow Algorithm for Three-phase Distribution Network Considering Distributed Power
ActiveCN104734148BAvoid divergenceThe operating state is close to the real situationInformaticsSpecial data processing applicationsDistribution power systemElectric distribution network
The invention discloses a three-phrase power-distributing network continuation power flow analysis of the distributed power supply, and belongs to the technical field of electrical power system static voltage stability analysis. According to the three-phrase power-distributing network continuation power flow analysis, by the introducing of the increasing relation between the active power output of load parameter simulation distributed power supply and the load power, a three-phrase power-distributing network continuation power flow equation with the load parameter is established, and a P-V curve of the three-phrase power-distributing network is traced with the method of prediction-parameterization-method correction. The invention also provides an identification method of branch-point type when the distributed power supply is connected. The grid-connected injection current spillage of the distributed power supply in the continuation power flow analyzing process is considered, a node-type bilateral switching logic is adopted to conduct the process, and the running state of the distributed power supply is more close to a real situation, so that the P-V curve of the three-phrase power-distributing network can be traced accurately, the voltage collapse critical point can be calculated accurately, and the branch-point type can be identified accurately.
Owner:HOHAI UNIV
A Continuous Power Flow Calculation Method Based on Local Geometry Parameterization
ActiveCN103116704BStep size control method is simpleConvergence problems ariseSpecial data processing applicationsAc networks with different sources same frequencyPower flowPower system scheduling
A method for obtaining a continuous power flow of an electric power system is provided. The method comprises: establishing first power flow equations for PQ buses, and establishing second power flow equations for PV buses; establishing power flow equations according to the first flow equations, the second power flow equations, and a voltage magnitude and a voltage phase of a balance bus; choosing a bus having a fastest voltage drop as a parameterization bus, and defining a parameterization variable according to a voltage magnitude of the parameterization bus and the load growth factor; defining an equality constraint equation according to the parameterization variable, and generating an extended power flow equation according to the equality constraint equation and the power flow equations; solving the extended power flow equation by a plurality of iterations to obtain a plurality of load summations; generating a P-V curve according to the plurality of load summations.
Owner:TSINGHUA UNIV
A Method for Obtaining the Uniaxial Stress-Strain Relationship of Materials by Small Punch Test
ActiveCN106124293BQuantitative evaluation of degradation performanceTo overcome the shortcomings such as large size restrictionsStrength propertiesSmall sampleMaterials testing
The invention discloses a method for obtaining uniaxial stress-strain relation of a material through a small punch test. After a continuous load-displacement curve of a stamped wafer sample is obtained, power-law fitting is conducted on the stage III of the P-V curve, obtained load characteristics and displacement indexes are introduced to a Hollomon equation so as to obtain the uniaxial stress-strain relation of the material. The method is suitable for ductile and power-law isotropic hardening materials, the uniaxial stress-strain relation of the material can be obtained only by cutting out a small wafer sample from an existing member in special circumstances such as high temperature and irradiation, and accordingly the degradation properties of the material are assessed. The method has weaker destructiveness on the existing member, achieves the micro-damage detection, sample processing and testing principles are simpler, obtained results have higher accuracy, the shortcoming that a traditional uniaxial drawing test is largely limited by material size and the like is overcome, and the cost lower. The method has the greater advantages in testing of precious-metal servicing micro-force materials establishing constitutive relation of minimally invasive wafers and other small samples.
Owner:SOUTHWEST JIAOTONG UNIV
A multi-step-based maximum power tracking control method for photovoltaic power generation systems
ActiveCN104298295BHigh speedHigh stability and precisionPhotovoltaic energy generationElectric variable regulationCells panelEngineering
The invention discloses a multi-step size based photovoltaic power generation system maximum power tracking control method. The multi-step size based photovoltaic power generation system maximum power tracking control method comprises the steps of firstly setting an initial disturbance step size; utilizing a function M=V*abs (dP / dV) to conduct demarcation on a photovoltaic cell P-V curve, taking step size d1 in a left-side region of a maximum power point when a value of a function dM / dV is greater than 0; taking step size d1*M / P when the value of the function dM / dV is smaller than 0; taking step size d2 in a right-side region of the maximum power point when a value of the function M is greater than power P; taking step size d2*M / P when the value of the function is smaller than the power P; The multi-step size based photovoltaic power generation system maximum power tracking control method is simple and practical, and the proportional relation of an initial fixed step size can be determined by utilizing photovoltaic cell panel parameters provided by a manufacturer. The problem that steady accuracy and dynamic tracking speed cannot be simultaneously considered in most of maximum power tracking controls is solved by means of the method.
Owner:SOUTH CHINA UNIV OF TECH +1
Method and system for realizing static voltage stability monitoring in power system
The invention relates to a method and system for realizing static voltage stability monitoring in a power system. The method includes: constructing a power flow equation corresponding to the direct power flow method, and solving the initial transitional operation state of the system according to the power flow equation; detecting the solved initial transitional operation state to judge whether the preset switching condition is met, and if so, constructing a continuous The extended power flow equation corresponding to the power flow method, according to the extended power flow equation, solves the stable transitional operating state of the system; generates the system P-V curve according to the solved initial transitional operating state and stable transitional operating state, and then obtains the static voltage stability when the power system load changes Power limit value and voltage threshold value information. The invention not only increases the speed of P-V curve generation, but also ensures the accuracy of P-V curve generation, and can quickly and accurately obtain the power limit value and voltage critical value information of static voltage stability when the power system load changes.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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