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396 results about "Volt-ampere" patented technology

A volt-ampere (VA) is the unit used for the apparent power in an electrical circuit. The apparent power equals the product of root-mean-square (RMS) voltage and RMS current. In direct current (DC) circuits, this product is equal to the real power (active power) in watts. Volt-amperes are useful only in the context of alternating current (AC) circuits (sinusoidal voltages and currents of the same frequency). The volt-ampere is dimensionally equivalent to the watt (in SI units, 1 VA = 1 N m A⁻¹ s ⁻¹ A = 1 N m s ⁻¹ = 1 J s ⁻¹ = 1 W).

System, Device and Method for Regulating Volt-Ampere Reactance in a Power Distribution System

A system, method and product for modifying the volt-ampere reactive (VARs) in a power distribution system is provided. In one embodiment, the method includes determining the VARs at a location on the power distribution system and based on the determined VARs, determining whether to modify the VARs. If it is determined to modify the VARs the method includes identifying a plurality a capacitor banks connected to a power line and from the identified plurality of capacitor banks, generating a list of eligible capacitor banks that satisfy inclusion criteria. If the list of eligible capacitor banks includes at least one capacitor bank the method includes selecting a capacitor bank from the list of eligible capacitor banks and transmitting a switching command for the selected capacitor bank. Generating the list of eligible capacitor banks may include one or more of ensuring the voltage at each capacitor bank is not beyond a threshold, ensuring the total harmonic distortion at each capacitor bank is not beyond a threshold, ensuring the capacitor bank has not been switched within a recent predetermined time period, ensuring the capacitor bank has not been switched more than a predetermined number of times within a recent time period, ensuring that communications with each capacitor bank are viable, and other criteria.
Owner:S&C ELECTRIC

Method for simultaneously detecting three antibiotic residues including streptomycin, chlorampenicol and tetracycline based on nucleic acid aptamer and quantum dots

The invention relates to a method for simultaneously detecting three antibiotic residues including streptomycin, chlorampenicol and tetracycline based on nucleic acid aptamers and quantum dots and belongs to the technical field of analytical chemistry. Three-section complementary cDNA 1 sequences are designed and synthesized and are complemented with three antibiotic aptamers DNA sequences and are further complemented with respective capturing probe DNA sequences of three antibiotics and complementary cDNA 2 sequence part. The three cDNAs 1 are first hybridized with aptamer DNAs supplemented with each other to form double-stranded DNAs. When target antibiotics exist in a sample, the aptamer DNAs are combined with corresponding antibiotics as a priority to cause the double-stranded DNAs to be de-hybridized and release cDNAs 1. The free cDNAs 1 are combined with capturing probe DNAs modified on the surface of a gold electrode, and cDNAs 2 modified with three quantum dots are hybridized with the other end of each cDNA 1. The three quantum dots on the surface of the gold electrode generate dissolution volt-ampere peaks corresponding to the target antibiotics. The three antibiotics are detected by utilizing the relations of changes of peak current values and antibiotic concentration. The method is good in repeatability and stability and high in sensitivity and can be used for directly measuring the three antibiotic residues in samples such as milk.
Owner:ANHUI HUATENG AGRI TECH CO LTD

Method of controlling running of modularized multi-level converter in low frequency model

InactiveCN103337977ASimplified generation methodVersatilityAc-dc conversionDifferential coefficientModel selection
The invention relates to a method of controlling running of a modularized multi-level converter in a low frequency model, which belongs to the technical field of controlling multi-level power electronic converters. The method comprises the following steps: setting high frequency common mode voltage and high frequency ring current both required to be superimposed, revising a switching function of a submodule and bridge arm current, obtaining an expression of capacitance voltage differential coefficient of the submodule according to volt-ampere characteristics of capacitance of the submodule, and in order to allow the capacitance voltage of the submodule to only have high-frequency component, assuming high frequency common mode voltage is known to obtain a expression of the high frequency circular current; comparing a running frequency with a critical frequency to obtain frequency model selection signals, combining an energy control and a circular current control of a phase unit of the modularized multi-level converter, determining whether the high frequency common mode voltage and the high frequency circular current are required to be superimposed to an original instruction or not according to the frequency model selection signals, and generating voltage required to be superimposed in the bridge arm of the phase unit of the high frequency circular current by controlling. The method is easy to realize and strong in universality, and provides reference for low frequency application of the modularized multi-level converter.
Owner:SOUTHEAST UNIV

Photovoltaic model establishment method applicable to dynamic overall-process simulation of power system

The invention relates to a photovoltaic model establishment method applicable to the dynamic overall-process simulation of a power system. A photovoltaic generation module is modeled, a temperature factor and an illumination intensity factor in the medium and long-term process have the characteristics of fluctuation and indeterminacy, and an implementation method of a photovoltaic maximum power tracing model for the dynamic overall-process simulation of the power system is provided in consideration of the influence on photovoltaic generation caused by the change of the two factors. The photovoltaic maximum power tracing model adjusts the working voltage of a photovoltaic cell panel according to the volt-ampere characteristics of a photovoltaic power supply by using a maximum power point tracing control method, so that the photovoltaic cell panel can work in a maximum power output state, solar energy is utilized to the greatest extent, and the efficiency and performance of the photovoltaic generation are effectively improved. An inverter effectively controls the injection current of axes d and q by virtue of an inner ring current control loop and an outer ring current control loop, so that active power and reactive power can be controlled. The whole model meets requirements for electromechanical transient overall-process simulation and medium and long-term dynamic overall-process simulation of the power system.
Owner:STATE GRID CORP OF CHINA +2

Performance degradation monitoring system for photovoltaic cell

The invention discloses a performance degradation monitoring system for a photovoltaic cell. The system comprises a testing light source module, an I-V curve detection module, a channel switching module, a load loading module, a communication control unit and a processing terminal, wherein the I-V curve detection module detects a volt-ampere characteristic curve outwards output by the photovoltaic cell device; the processing terminal calculates the optimal load value of the maximum power point of the photovoltaic cell device according to the volt-ampere characteristic curve detected by the I-V curve detection module; the load loading module loads a load resistor of the corresponding resistance on the photovoltaic cell device according to the optimal load value. The load obtained by calculation is loaded on the detected photovoltaic cell device through the load loading module, and therefore the photovoltaic cell device does work outwards all the time in the testing process, the process better accords with actual situations of the photovoltaic cell device in the actual working process, and the degradation of the device in the actual working state is simulated more objectively and accurately.
Owner:苏州德睿科仪仪器设备有限公司

Volt-ampere characteristic testing system of solar cell photovoltaic device

A volt-ampere characteristic testing system of a solar cell photovoltaic device belongs to a photoelectric testing device and solves problems that an existing testing system needs to set irradiance through manual operation, and irradiance determining and sample battery testing cannot be carried out simultaneously. The volt-ampere characteristic testing system comprises a sunlight simulator, an irradiance choosing device, an irradiance determining device, a battery testing device and a computer. The sunlight simulator is composed of a an xenon lamp on an optical path and filtering sheets with air quality of 1.5, and the irradiance choosing device and the irradiance determining device are sequentially arranged on an output optical path of the solar simulator. A direct current voltage source supplies power to the irradiance choosing device and irradiance determining device. The battery testing device is connected with the computer through a general purpose interface bus. The volt-ampere characteristic testing system is simple in assembly, fast and easy to operate, all required devices and components can be bought at the market, elements can be acquired easily, and the volt-ampere characteristic testing system can accurately and automatically give out a characteristic curve in real time.
Owner:HUAZHONG UNIV OF SCI & TECH

A method for extracting solar cell parameters

The invention discloses a method for extracting parameters of a solar cell, which is applied to the technical field of energy sources. The method comprises the following steps of: (1) measuring a dark volt-ampere characteristic curve of the solar cell; (2) measuring a dark conductance voltage characteristic curve and a dark differential conductance voltage characteristic curve of the solar cell; and (3) fitting the dark volt-ampere characteristic curve, the dark conductance voltage characteristic curve and the dark differential conductance voltage characteristic curve of the solar cell by adopting a theoretical formula to obtain series resistance, shunt resistance, an ideal factor and reverse saturation current of the solar cell, wherein the series resistance, the shunt resistance, the ideal factor and the reverse saturation current satisfy minimum standard deviations between experimental data and the theoretical formula. Compared with the traditional method of only relying on a single volt-ampere characteristic (or conductance voltage characteristic) curve under illumination to fit and extract parameters of the solar cell, the method disclosed by the invention has the characteristics of higher accuracy and stronger applicability.
Owner:NANCHANG HANGKONG UNIVERSITY

DNA biosensor based on three-dimensional ordered gold doped nano titanium dioxide electrode as well as preparation method and application of DNA biosensor

The invention discloses a DNA biosensor based on a three-dimensional ordered gold doped nano titanium dioxide electrode and a preparation method as well as a method for detecting breast cancer genes by using the sensor. The preparation method comprises the following steps: preparing a three-dimensional ordered gold doped nano titanium dioxide film electrode (3DOMGTD/ITO) on an ITO (indium tin oxide) electrode by adopting a template method; then dropping a DNA probe (5'-Fc-ssDNA) labeled with ferrocene at 5' end on the electrode, thereby preparing a modified electrode, namely the DNA biosensor; placing the modified electrode in a solution of a breast cancer gene segment, hybridizing, detecting the variation of hybridization signals by adopting a differential pulse volt-ampere method, and carrying out electrochemical detection on the breast cancer gene. According to the invention, the label-type DNA biosensor is prepared by utilizing the specificity recognition effect between the DNA probe and the breast cancer gene, and the DNA biosensor has favorable stability, reproducibility and electrode regeneration, and can be applied to the field of DNA hybridization and tumor electrochemical detection.
Owner:NANJING NORMAL UNIVERSITY

Tester

InactiveCN102707173AOvercome functionOvercome the shortcomings of cumbersome measurement wiringTesting dielectric strengthTest efficiencyTransformer
The invention discloses a tester. The tester comprises a power supply module, a first measuring module, a second measuring module and a master control module. The power supply module is used for providing a test power supply capable of adjusting voltage and frequency continuously. The first measuring module can obtain an output voltage and an output current of the power supply module in real time and performs predetermined volt-ampere characteristics treatment, no-load treatment or load treatment to the output voltage and the output current so as to realize the PT (Predetermined) volt-ampere characteristics, and single phase no-load and single phase load test of a transformer. The second measuring module is used for monitoring the high voltage side voltage of the transformer during an alternating current voltage withstand test of the transformer, and feeds the value to the master control module, so that the master control module adjusts the output of the power supply module according to the high voltage side voltage value and the predetermined withstand voltage value so as to perform the alternating current withstand voltage test of the transformer. Therefore, the tester provided by the invention integrates the test functions such as PT volt-ampere characteristics, single phase no-load and single phase load test of the transformer and alternating current voltage withstand test, thereby improving the test efficiency.
Owner:国网吉林省电力有限公司延边供电公司 +1

Photovoltaic power generation system online IV curve test device and test method

The invention discloses a photovoltaic power generation system online IV curve test device and a test method. The online IV curve test device comprises a temperature acquisition system, a solar irradiance gauge, a multi-channel photovoltaic assembly IV tester, an industrial control computer, a switch, a host computer and a switching case. According to the online IV curve test device, a relay with relatively low cost and having no arc discharge is employed to switch photovoltaic assemblies, IV curves of the assemblies are respectively tested through rapid scanning, accurate volt-ampere characteristics of the photovoltaic assemblies are acquired, and the online IV curve test device satisfies online IV curve tests on all channel assembly strings through cascade networking at present. Through the method, after switching one assembly at each time, an output voltage of the residual assembly string is guaranteed to be greater than the lowest input work voltage of an inverter, and a cell input power is further guaranteed to be greater than a normal start power of the inverter. The whole test period of rapid assembly switching, rapid IV curve scanning test and rapid switching recovery is controlled to be quite short, the online IV curve test function is realized.
Owner:蚌埠电子信息产业技术研究院 +1

Highly-integrated Langmuir probe diagnosis system and method

The invention discloses a highly-integrated Langmuir probe diagnosis system and method. The highly-integrated Langmuir probe diagnosis system comprises a Langmuir probe, a trigger, a scanning power supply, a data acquisition unit and a data processing unit. The trigger transmits a pulse trigger signal to the scanning power supply via an optical fiber to trigger generation of sawtooth voltage with designated amplitude, period and repeat account, and the sawtooth voltage is loaded onto the Langmuir probe; the data acquisition unit carries out rapid, multiple and synchronous acquisition and storage on the voltage and current data of the Langmuir probe; and after completion of data acquisition, all the results are sent to the data processing unit in one shot, a data processing program on a computer is employed for automatic processing and analysis, and an acquired volt-ampere characteristic curve and acquired plasma parameters are displayed. The highly-integrated Langmuir probe diagnosis system has high automation degree and integrated level, can realize high-speed synchronous data acquisition and large-quantity data storage and communication, employs data processing for automatic processing and analysis of acquired data and provides a good man-machine interaction interface for displaying and recording of processing results.
Owner:HUAZHONG UNIV OF SCI & TECH

Distributed photovoltaic module string and module IV characteristic curve on-line measurement system

The invention relates to a distributed photovoltaic module string and module volt-ampere (IV) characteristic curve on-line measurement system, which comprises a photovoltaic module wireless voltage sensor, a photovoltaic subarray IV curve scanning module and an upper computer data management center. The photovoltaic module wireless voltage sensor is used for measuring module voltage, is powered by a super-capacitor and a photovoltaic module, and transmits voltage data to the IV curve scanning module through a wireless sensor network; the IV characteristic curve scanning module carries out time-sharing IV curve scanning on each module string, triggers the voltage sensor of a module to acquire synchronous voltage data so as to realize module IV curve scanning, and transmits IV data of the modules and the module strings to the upper computer data management center. The distributed photovoltaic module string and the module volt-ampere (IV) characteristic curve on-line measurement system provided by the invention can acquire accurate photovoltaic module string and module IV characteristic curve data on-line and in real-time, so that the efficiency and the accuracy in testing, evaluating and diagnosing a photovoltaic power generation array are effectively improved.
Owner:FUZHOU UNIV
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