DC Voltage Measurements Research Articles

High Impedance Active Probe for High Voltages

The probe was designed for the measurement of DC voltages of up to 30 kV from high impedance sources. It is based on a resistive divider with a total resistance of 200 GΩ and a step-down factor of 10’000. In order to allow the measurement of the stepped down voltage with a conventional multimeter without loading, the signal was buffered with an operational amplifier. The device was calibrated against a commercial probe using a low impedance high voltage source. A linear relationship was obtained for a high impedance resistive ladder for voltages between 3 and 30 kV, with a coefficient of determination (R2) of 0.9999. The low-cost device (ca. US $200) fills an application niche not addressed by commercial products.

Metrological Support in the field of DC Voltage and EMF Measurements: from Normal Elements to a Quantum Standard

The article deals with the issues of metrological support on the example of the highest level of the State Verification Scheme for measuring instruments of direct current voltage and electromotive force. The origin and development of reference measurements of DC voltage and electromotive force in the Russian Empire, the USSR, and modern Russia is briefly reviewed. The results of work on improving the State Primary Standard GET 13 completed in 2022 are presented.

Nanostructure-Based Solution Sensor Fabricated with p-CuOx/n-TiO2 Nanojunctions To Identify Species and Concentrations of Alcohol Molecules.

Chemiresistive sensors fabricated based on metal-oxide-semiconductors, the most widely used high-sensitivity sensor materials, are required for detecting target solutions and gases and identifying them with a high degree of accuracy. In this study, we used p-n nanojunctions and nanowire shapes for identifying alcohol solutions. The solution sensors fabricated based on CuOx nanowires with p-CuOx/n-TiO2 nanojunctions detected ethanol, ethylene glycol, and diethylene glycol solutions via DC voltage and electrochemical impedance measurements. The p-n nanojunctions affected the sensors' sensitivity in the diethylene glycol solution, and the nanowire surface areas affected the relaxation time in ethanol and ethylene glycol solutions. To identify alcohol solutions, principal component analysis was performed based on the relationship between the sensor information, such as the presence of p-n nanojunctions and nanowire surface areas, and the sensing performance. This analysis identified alcohol molecular species and predicted alcohol-solution concentrations in the 0.1-20 vol % range with a high degree of accuracy. The concept of using sensors with different surface conditions with respect to p-n nanojunctions and nanowire surface areas offers designs for metal-oxide-semiconductor sensors to identify various molecules in solution.

Characterization of developed low thermal scanner for DC voltage measurement

A low thermal scanner has been completely developed for improving DC voltage calibration from semi-automatic to fully automatic measurement system. The application of the switching system inside the built-up scanner introduced offset voltage to the measurement due to thermal electromotive force (EMF). A differential measurement method was proposed to characterize the thermal EMF of the scanner, and this method has been compared to previous characterization using the direct measurement method. The results show that the differential measurement method could minimize the thermal EMF effect, and the thermal EMF had a negligible contribution to the measurement for uncertainty levels around 10 to 11 ppm. Therefore, the differential measurement method is recommended for DC voltage calibration with uncertainty levels below 10 ppm since the thermal EMF can significantly affect the measurement. Furthermore, the direct measurement method is suggested for DC voltage calibration with uncertainty levels above 11 ppm since it can speed up the measurement process.

Thermal Flow Meter with Integrated Thermal Conductivity Sensor.

This paper presents a novel gas-independent thermal flow sensor chip featuring three calorimetric flow sensors for measuring flow profile and direction within a tube, along with a single-wire flow independent thermal conductivity sensor capable of identifying the gas type through a simple DC voltage measurement. All wires have the same dimensions of 2000 μm in length, 5 μm in width, and 1.2 μm in thickness. The design theory and COMSOL simulation are discussed and compared with the measurement results. The sensor's efficacy is demonstrated with different gases, He, N2, Ar, and CO2, for thermal conductivity and thermal flow measurements. The sensor can accurately measure the thermal conductivity of various gases, including air, enabling correction of flow rate measurements based on the fluid type. The measured voltage from the thermal conductivity sensor for air corresponds to a calculated thermal conductivity of 0.02522 [W/m·K], with an error within 2.9%.

Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements. This paper studies the traceability technology of electric energy value for automotive high-power DC chargers, including: (1) the traceability method of the built-in DC energy meter and shunt of the charger; (2) precision DC high current and small precision DC voltage output and measurement technology. This paper designs a 0.1 mA~600 A DC high current measurement system and proposes a 0.005 level DC power measurement traceability system. The uncertainty evaluation experiment of the DC power measurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper. The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.

An Adaptive Control of Remote Hybrid Microgrid based on the CMPN Algorithm

• The paper proposes a decentralized droop-based control technique power flow through the ILC, meanwhile, to keep the dc microgrid voltage and the ac microgrid frequency within their acceptable ranges. • To overcome the continuous operation of ILC, The modified droop control based CMPN algorithm is used to determine the necessity of operation of hybrid microgrid by estimating the status of the ac and dc microgrids by comparing local measurements with their critical values at both sides. • An adaptive filtering algorithm based on continuous mixed P-norm (CMPN) algorithm is utilized for the proposed autonomous control strategy to insure adaptive tuning of the controller parameters. The variable step size feature of the CMPN algorithm results in fast response compared to other techniques such as robust mixed-norm and the least absolute deviation techniques. The robustness against impulsive noise while having fast convergence, compared to other algorithms, render the CMPN algorithm to be an effective technique for online adaptation of the PI controller used for the ILC, especially in an islanded archetype to maintain the stability of the network. • A comparison between the proposed strategy based on both CMPN algorithm and adaptive PI control under different loading conditions are implemented to validate the proposed methodology. This paper proposes a new adaptive communication-less control strategy to enhance the dynamic performance of the interlinking converter (ILC) of a remote hybrid microgrid. The proposed autonomous strategy is based on the continuous mixed P-norm (CMPN) algorithm to simultaneously maintain the frequency of ac-side and the voltage of dc-side of the ILC within their acceptable ranges under various conditions. The variable step nature of the CMPN algorithm and robustness ensure stable operation of the proposed strategy for the ILC. In addition, the power sharing between both sides of the ILC is achieved by a modified ac-dc droop control to avoid using any communication systems between different distributed generators (DG). Moreover, a simple algorithm is used to determine the desired power flow direction based on local measurements of dc voltage and frequency. The proposed CMPN algorithm provides an online adaption of the controller's parameters to avoid the need for fine tuning or optimization techniques under various operating conditions. The dynamic performance of the proposed autonomous control strategy is evaluated using the PSCAD/EMTDC simulation package under different operating modes. The results demonstrate the superior dynamic performance of the proposed strategy based on the CMPN algorithm compared to the adaptive PI (API) controller in terms of fast response and tight regulation of power flow, voltage and frequency under different conditions. Compared to API, it has been found that the proposed controller results in more improvement of the dc-side voltage within the operating frequency range of the ac-side of the ILC.

Design and implementation of high-precision voltage measurement system based on Kalman filter and automatic calibration technology

With the rapid development of science and technology, precision measurement is of increasing importance. In this paper, we discuss noise reduction and automatic calibration issues for a high-precision voltage measurement system that covers voltages from 0.1 µV to 300 V and a frequency range from 10 Hz to 300 kHz (including DC). First, a modified Kalman filter is proposed to reduce measurement noise. Then, a self-calibration circuit is constructed to eliminate the systematic errors in DC voltage (DCV) measurements. Finally, a wideband AC calibration model is developed to overcome the defects in AC voltage (ACV) measurements caused by AC characteristics. The measurement application demonstrates the effectiveness of the proposed methods----the designed voltage measurement system has a DCV measurement accuracy of better than 9 µV/V and a high ACV accuracy of 0.25 mV/V in the frequency range of 30 Hz to 30 kHz at an ambient temperature of 25 °C. In addition, the minimum DC measurement uncertainty obtained on the DCV 10 V range is 0.4 μV/V (type A) and the minimum AC measurement uncertainty obtained on the ACV 10 V range is 2 μV/V (type A).

Predictive Current Control and Field-Weakening Operation of SPMSM Drives Without Motor Parameters and DC Voltage

The prior model-parameter-free predictive current control (MFPCC) applies a 1-D lookup table (1-D LUT) to store current variation, where the index input is the number of the basic voltage vector. However, current variation is not only related to the input voltage but also depends on the rotor position. As the influence of rotor position is not considered in the prior MFPCC, high current spikes may occur during normal operation. Aiming to improve the steady-state performance, the proposed MFPCC utilizes a 2-D LUT to backup current variations, where the second-dimensional input is the discretized rotor position. The proposed method keeps good robustness and eliminates current spikes in the prior MFPCC. Moreover, a field-weakening (FW) method is developed to extend the speed range. As no modulator is employed in MFPCC and only discrete voltage vectors are available, the conventional voltage magnitude-based FW control scheme cannot be directly applied. To address such issue, a complex-coefficient filter is employed to calculate the modulation index of the fundamental voltage, which is then fed to the FW controller to generate demagnetizing current. The proposed MFPCC can achieve satisfactory performance without motor parameters and the measurement of dc voltage. Experimental results confirm the effectiveness of the proposed method.

Electromagnetically induced transparency based Rydberg-atom sensor for traceable voltage measurements

We investigate the Stark shift in Rydberg rubidium atoms through electromagnetically induced transparency for the measurement of direct current (dc) and 60 Hz alternating current (ac) voltages. This technique has direct application to the calibration of voltage measurement instrumentation. We present experimental results for different atomic states that allow for dc and ac voltage measurements ranging from 0 to 12 V. While the state-of-the-art method for realizing the volt, the Josephson voltage standard, is significantly more accurate, the Rydberg atom-based method presented here has the potential to be a calibration standard with more favorable size, weight, power, and cost. We discuss the steps necessary to develop the Rydberg atom-based voltage measurement as a complementary method for dissemination of the voltage scale directly to the end user and discuss sources of uncertainties for these types of experiments.

PMU-Based State Estimation for Networks Containing LCC-HVDC Links

This letter proposes an equality-constrained weighted least squares (WLS) state estimation model for networks containing LCC-HVDC links. Voltage and current phasor measurements for the AC network are provided by phasor measurement units (PMUs) and DC voltage and current measurements for the DC transmission lines are acquired by appropriate DC sensors. AC/DC coupling equations and zero injections are treated as equality constraints. Simulation results for a 6-bus hybrid AC/DC network are shown to validate the proposed model and algorithm.

Non-intrusive DC voltage measurement based on resonant electric field microsensors

Based on the resonant electric field microsensors with coplanar electrodes, a novel non-intrusive measurement scheme of DC power-line voltage suitable for actual product is presented in this paper. Compared with using microsensors directly without some protection, employing the proposed scheme can avoid the influence of humidity and electromagnetic disturbance on non-contact voltage measurement. A theoretical model is developed to analyze the influence of the structural parameters of the proposed measurement scheme on its sensitivity and to predict the voltage response. Furthermore, the theoretical analysis reveals that the proposed scheme obtains the DC power-line voltage non-intrusively by measuring the voltage of a floating electrode. A prototype of the non-intrusive measurement apparatus of DC power-line voltage has been developed, calibrated, and tested. The prototype shows a favorable linear response characteristic with a linearity of 0.86%. And the experimental results are in good agreement with the theoretical results. The maximum relative deviation noticed is −2.16% over a range of voltages from −1000 V to 1000 V.

A revised methodology to analyze the rectenna power conversion efficiency based on antenna/rectifier interface losses

Despite the high number of scientific reports on rectenna applications, the influences of antenna/rectifier interface over the power conversion efficiency have not yet been profoundly debated in the literature. In this context, equations that fully characterize the matching and power transmission processes within the antenna/rectifier interface are developed and presented in this work, applying the Two-Port Power Gain definitions in rectenna analysis. Rectenna designs presented in previous works were used here as test cases to introduce the problem and experimentally validate the revised methodology and results. The overall rectenna power conversion efficiency was equated as a function of the antenna/rectifier interface matching losses, which proved to be responsible for 20–50% of the power conversion efficiency reduction for the tested cases. In conclusion, the equations presented, based only on conventional power, S-Parameter and DC voltage measurements, represent an alternative tool in the design of matching and rectification solutions for rectennas.

MICROPROCESSOR SYSTEM FOR INVESTIGATION OF SENSOR CHARACTERISTICS ON THE BASIS OF POROUS SILICON

Development of integrated sensors is a promising scientific and technical direction to create components for measurement and information systems. Among the different types of analyser one of the places are occupied by sensors of hydrogen containing compounds in gaseous and liquid condition (especially poisonous and carcinogenic). Fixing the presence of a substances in the gas or liquid environment is an actual task for scientific, industrial and medical application areas. The main goal of this paper an inexpensive microprocessor system for measuring and analyzing electrical properties of nanocomposite sensing material such as porous silicon on the base of current and capacity-voltage characteristics and its hardware and software applying is represented. The microprocessor system is designed for measuring sensors current-voltage and capacity-voltage characteristics based on porous silicon and nanocomposite structures and consists of the following units: power supply unit, DC voltage regulator, control and measurement module, RLC-meter E7-22, UART/USB and RS232/USB converters, measuring cell, PC. The software of the microprocessor system for measuring consists of the software for the control and measurement module implemented on the Atmega 128 microcontroller and the main device management software for the PC. The main program algorithm and software are implemented in the C# programming language in the Visual Studio 2017 environment The results of the comparison allow us to conclude that the implemented modules of the microprocessor system for sensors I-V- and C-V characteristics testing can be used in the development of portable environmental monitoring devices, to study porous silicon sensors using them. Keywords — porous silicon, nanocomposite; sensor, microcontroller, microprocessing system, current-voltage characteristic

Bilateral comparison of 10 V standards between the NSAI-NML (Ireland) and the BIPM

Main textAs part of the ongoing BIPM key comparison BIPM.EM-K11, a comparison of the 10 V voltage reference standards of the BIPM and the National Standards Authority of Ireland - National Metrology Laboratory (NSAI - NML), Dublin, Ireland, was carried out in November and December 2020. The objective for NSAI-NML in participating in this comparison was to demonstrate the international equivalence of its DC voltage measurement results and to support their calibration and measurement capabilities (CMCs) published in the Key Comparison Database of the BIPM (KCDB).Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_8 (Z8) and BIPM_9 (Z9), were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage at the 10 V level consists of a group of characterized Zener diode-based electronic voltage standards. The output EMF (Electromotive Force) of each travelling standard was measured by direct comparison with the group standard.At the BIPM the travelling standards were calibrated, before and after the measurements at NSAI-NML, with the Josephson Voltage Standard, developed at the BIPM. The output EMF of each travelling standard was measured against the Josephson Voltage Standard (JVS). Results of all measurements were corrected for the dependence of the output voltages of the Zener standards on internal temperature and ambient atmospheric pressure.The comparison result is presented as the difference between the value assigned to a 10 V standard by NSAI-NML, at NSAI-NML, U NSAI-NML, and that assigned by the BIPM, at the BIPM, U BIPM, on the reference date of 2020/11/14, as U NSAI-NML - U BIPM = -2.99 µV; u c = 1.71 µVwhere u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realization of the volt at NSAI-NML, and the uncertainty related to the comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Bilateral comparison of 1.018 V and 10 V standards between the BIM (Bulgaria) and the BIPM (BIPM.EM-K11.a and b)

Main textAs part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and the Bulgarian Institute of Metrology, BIM, was carried out in April 2019. The objective for BIM in participating in this comparison was to demonstrate the international equivalence of its DC voltage measurement results and to support the calibration and measurement capabilities (CMCs) published in the Key Comparison Database of the BIPM (KCDB).Two BIPM Zener diode-based travelling standards (Fluke 732B) were shipped to Sofia in March 2019.At the BIPM, the reference standard for DC voltage is a primary voltage standard based on the Josephson effect, developed by the BIPM. The output electromotive force (EMF) of each travelling standard was measured against the Josephson Voltage Standard (JVS) before and after the measurements at BIM. At the BIM, the reference standard is a commercial JVS.The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by BIM, at the level of 1.018 V and 10 V, at BIM, UBIM, and those assigned by the BIPM, at the BIPM, UBIM, at the reference dates of the 26th of March 2019. UBIM - UBIM = - 0.01 µV; uc = 0.02 µV, at 1.018 V UBIM - UBIM = + 0.30 µV; uc = 0.09 µV, at 10 Vwhere uc is the combined standard uncertainty associated with the measured difference.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Accelerating the separation of emulsified oil products using high electrostatic fields

To create an oil-based emulsified liquid, a blend of glycerol and biodiesel was stabilized with the aid of sodium oleate as an emulsifier. The time taken by the glycerol to settle down from the biodiesel under the sole effect of gravity has been compared to that attained under the influence of high electrostatic fields. Experiments were designed to study the effect of the employed electrode pairs, electrode distance, and voltage magnitude and polarity on the separation rate of glycerol. High DC voltage measurements and laser beam intensity readings were recorded every second via a computational micro-controller program. Results showed that the time taken to achieve 100% separation completeness under gravity reached 30,000 s (8.3 h). However, when an electrode pair was submerged to the proper height (4 cm apart) and the voltage was set to 2000 V, 99.02% separation completeness was reached within 1800 s (0.5 h). When the effect of the employed electrode pairs was studied, the obtained results revealed that the electrode pairs of different diameters gave the highest percentage of separation completeness and the shortest separation time at 4000 V. Gas chromatography (GC) analysis was performed to biodiesel samples before and after applying the high voltage. The results do not indicate the appearance of any foreign peaks, which confirms that the applied voltage has not create, or even initiate, any chemical reactions. Concerning the physical properties before and after applying the high voltage, insignificant changes has been measured in the density, refractive index, flash point, and water content.

Real-Time Implementation of Shunt Active Power Filter With Reduced Sensors

Performance of shunt active power filter (SAPF) depends on the effectiveness of control strategy, which requires information about voltages and currents obtained from sensors. Faults in these sensors cause SAPF to aggravate power quality problems instead of compensating it. Therefore, sensorless control of SAPF is a very attractive solution for its robust operation. This article proposes an Adaline-based control strategy that requires only source currents and dc voltage measurement, thus reducing source voltage and load current sensors. The proposed estimation techniques enable SAPF to work under highly dynamic load conditions where other similar approaches with reduced sensors cease to perform. A comparative analysis with the classical approach (using all sensors) under the same load conditions is done to show the effectiveness of the proposed techniques. The proposed control strategy is first simulated on MATLAB/Simulink platform and further verified on the OPAL-RT 5700 hardware-in-loop FPGA-based real-time platform.

Tackling Challenges in Seebeck Coefficient Measurement of Ultra‐High Resistance Samples with an AC Technique

AbstractSeebeck coefficient is a widely studied semiconductor property. Conventional Seebeck coefficient measurements are based on DC voltage measurement. Normally this is performed on samples with moderate resistances (e.g., below a few MΩ level). Certain semiconductors are intrinsic and highly resistive. Many examples can be found in optical and photovoltaic materials. The hybrid halide perovskites that have gained extensive attention recently are a good example. Despite great attention from the materials and physics communities, few successful studies exist of the Seebeck coefficient of these compounds, for example CH3NH3PbI3. An AC‐technique‐based Seebeck coefficient measurement is reported, which makes high‐quality Seebeck voltage measurements on samples with resistances up to the 100 GΩ level. This is achieved through a specifically designed setup to enhance sample isolation and increase capacitive impedance. As a demonstration, Seebeck coefficient measurement of a CH3NH3PbI3 thin film is performed at dark, with sample resistance 150 GΩ, and found S = +550 µV K−1. The strategy reported could be applied to the studies of fundamental transport parameters of all intrinsic semiconductors that have not been feasible.

Research on Liquid Metal Energy Storage Battery Equalization Management System in Power PSS

Power Product-Service Systems(PSS) combines industrial electric products, such as new energy supplier, with electric energy services. Batteries that is a new energy supplier are widely used in smoothing power fluctuation to improve power product service. A new kind of battery, liquid metal battery (LMB) is studied in this paper. First, the charge and discharge characteristics of a single LMB and LMB series are studied, and the voltage curves of of LMB series with and without equalization are compared. Then, an equalization managing system is designed according to the series characteristics of LMB. This system is simulated and analyzed in PSPICE to verify the feasibility of equalization module. Finally, a testing platform is built to evaluate the equalization managing system. The results show that the realative error of the acquisition module for DC voltage measurement meets the requirements, which means this system has a good equalization function and significantly improve the power Product-Service Systems efficiency.