CPEM Digest (Conference on Precision Electromagnetic Measurements)
The paper focuses on the calibration techniques of non-conventional voltage and current measureme... more The paper focuses on the calibration techniques of non-conventional voltage and current measurement transformers. Calibration circuits set up at INRIM are described, which makes use of digital acquisition and numerical analysis of the transducer output. Examples of calibration of non-conventional instruments to be used as on-site references are discussed, which include a system based on Rogowski coil for live-on-site check of measuring current transformers with rated voltages up to 380 kV.
2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2013
ABSTRACT The importance of power quality monitoring in medium voltage (MV) systems has dramatical... more ABSTRACT The importance of power quality monitoring in medium voltage (MV) systems has dramatically increased in the last years. It is well known that a measurement system with wide bandwidth and very low distortion is mandatory for this purpose. Usually, the performance bottlenecks are the transducers which have to be carefully selected according to the required accuracy. Therefore, it is very important to test them in real-world (nonsinusoidal) operating conditions. However, the characterization requires generating arbitrary voltage waveforms with amplitude of several kilovolts. This paper proposes a very simple MV waveform generator employing basic instrumentation which is very common in calibration laboratories. It consists in an arbitrary waveform generator (AWG) connected to a power amplifier which feeds the low voltage winding of a step up transformer. The secondary, high voltage winding is attached to a reference voltage transducer and to the device under test. In general, the shape of the secondary voltage waveform can be very different from the reference voltage of the signal generator. However, assuming that the nonlinearities of the system are negligible, it is possible to estimate the transfer function between the reference voltage of the signal generator and the secondary voltage. Then, it is possible to compute the reference voltage for the AWG in order to obtain the desired secondary voltage waveform. This technique has been implemented and its performance has been tested. The experimental activity has shown that an accuracy of a few percent can be easily achieved.
IEEE Transactions on Instrumentation and Measurement, 2014
ABSTRACT Nowadays, voltage transducers in medium-voltage (MV) distribution networks operate in no... more ABSTRACT Nowadays, voltage transducers in medium-voltage (MV) distribution networks operate in nonsinusoidal conditions while their calibration is still based on simple sine-wave tests. A more significant characterization could be achieved using complex multitone signals. However, this requires an MV generator able to apply arbitrary voltage waveforms to the transducer under test. The authors have recently proposed a simple MV signal generator that can be effectively employed for this purpose. In this paper, the performance of this MV generator has been carefully analyzed. A characterization procedure based on multisine excitation has been proposed and tested. In particular, the main causes of uncertainty have been identified and their impact on the accuracy of the generated voltage evaluated. The analysis considers both linear and nonlinear effects, such as harmonic distortion and hysteresis.
2011 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2011
Abstract As well known, the availability of an advanced and reliable model describing the real be... more Abstract As well known, the availability of an advanced and reliable model describing the real behavior of a physical device may strongly simplify the measurement activities devoted to its characterization. A model driven approach can meaningfully reduce the amount and ...
2013 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2013
ABSTRACT Features and performances of a calibration system for both conventional and electronic m... more ABSTRACT Features and performances of a calibration system for both conventional and electronic measurement transformers with analog output are described. The calibration circuit includes standard current/voltage transformers as reference transducers and two synchronised digitizers which enable measurement of signals with amplitude that can differ up to three orders of magnitude. Best measurement uncertainty at power frequency (confidence level 95%) is estimated to be within a few hundreds of ppm and microradians for the ratio and phase error respectively. By making use of different acquisition strategies the same set-up can be employed for the frequency response measurement of transducers up to tens of kilohertz with enlarged uncertainty.
2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014
ABSTRACT The increasing interest in the use in medium and high voltage networks as well as in the... more ABSTRACT The increasing interest in the use in medium and high voltage networks as well as in the low voltage ones of non-conventional low power instrument measurement transformers entails the availability of dedicated calibration set-up, equipped with flexible and accurate measurement systems. The paper presents a measurement system for the calibration of both inductive and low power voltage and current transformers, which includes a low cost and digital acquisition and measurement equipment. It is based on a portable data acquisition system composed of various current and voltage data acquisition boards. The proposed system can be used for the calibration of transducers with analog output from DC up to tens of kilohertz and allows the comparison of signals of different kind and order of magnitude.
Metering accuracy is of essence in interconnections between Distribution and Transmission network... more Metering accuracy is of essence in interconnections between Distribution and Transmission networks, in order to ensure market correctness; all components of measurement chains, from instrument transformers to meters, must therefore be calibrated ...
CPEM Digest (Conference on Precision Electromagnetic Measurements)
The paper focuses on the calibration techniques of non-conventional voltage and current measureme... more The paper focuses on the calibration techniques of non-conventional voltage and current measurement transformers. Calibration circuits set up at INRIM are described, which makes use of digital acquisition and numerical analysis of the transducer output. Examples of calibration of non-conventional instruments to be used as on-site references are discussed, which include a system based on Rogowski coil for live-on-site check of measuring current transformers with rated voltages up to 380 kV.
2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2013
ABSTRACT The importance of power quality monitoring in medium voltage (MV) systems has dramatical... more ABSTRACT The importance of power quality monitoring in medium voltage (MV) systems has dramatically increased in the last years. It is well known that a measurement system with wide bandwidth and very low distortion is mandatory for this purpose. Usually, the performance bottlenecks are the transducers which have to be carefully selected according to the required accuracy. Therefore, it is very important to test them in real-world (nonsinusoidal) operating conditions. However, the characterization requires generating arbitrary voltage waveforms with amplitude of several kilovolts. This paper proposes a very simple MV waveform generator employing basic instrumentation which is very common in calibration laboratories. It consists in an arbitrary waveform generator (AWG) connected to a power amplifier which feeds the low voltage winding of a step up transformer. The secondary, high voltage winding is attached to a reference voltage transducer and to the device under test. In general, the shape of the secondary voltage waveform can be very different from the reference voltage of the signal generator. However, assuming that the nonlinearities of the system are negligible, it is possible to estimate the transfer function between the reference voltage of the signal generator and the secondary voltage. Then, it is possible to compute the reference voltage for the AWG in order to obtain the desired secondary voltage waveform. This technique has been implemented and its performance has been tested. The experimental activity has shown that an accuracy of a few percent can be easily achieved.
IEEE Transactions on Instrumentation and Measurement, 2014
ABSTRACT Nowadays, voltage transducers in medium-voltage (MV) distribution networks operate in no... more ABSTRACT Nowadays, voltage transducers in medium-voltage (MV) distribution networks operate in nonsinusoidal conditions while their calibration is still based on simple sine-wave tests. A more significant characterization could be achieved using complex multitone signals. However, this requires an MV generator able to apply arbitrary voltage waveforms to the transducer under test. The authors have recently proposed a simple MV signal generator that can be effectively employed for this purpose. In this paper, the performance of this MV generator has been carefully analyzed. A characterization procedure based on multisine excitation has been proposed and tested. In particular, the main causes of uncertainty have been identified and their impact on the accuracy of the generated voltage evaluated. The analysis considers both linear and nonlinear effects, such as harmonic distortion and hysteresis.
2011 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2011
Abstract As well known, the availability of an advanced and reliable model describing the real be... more Abstract As well known, the availability of an advanced and reliable model describing the real behavior of a physical device may strongly simplify the measurement activities devoted to its characterization. A model driven approach can meaningfully reduce the amount and ...
2013 IEEE International Workshop on Applied Measurements for Power Systems (AMPS), 2013
ABSTRACT Features and performances of a calibration system for both conventional and electronic m... more ABSTRACT Features and performances of a calibration system for both conventional and electronic measurement transformers with analog output are described. The calibration circuit includes standard current/voltage transformers as reference transducers and two synchronised digitizers which enable measurement of signals with amplitude that can differ up to three orders of magnitude. Best measurement uncertainty at power frequency (confidence level 95%) is estimated to be within a few hundreds of ppm and microradians for the ratio and phase error respectively. By making use of different acquisition strategies the same set-up can be employed for the frequency response measurement of transducers up to tens of kilohertz with enlarged uncertainty.
2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014
ABSTRACT The increasing interest in the use in medium and high voltage networks as well as in the... more ABSTRACT The increasing interest in the use in medium and high voltage networks as well as in the low voltage ones of non-conventional low power instrument measurement transformers entails the availability of dedicated calibration set-up, equipped with flexible and accurate measurement systems. The paper presents a measurement system for the calibration of both inductive and low power voltage and current transformers, which includes a low cost and digital acquisition and measurement equipment. It is based on a portable data acquisition system composed of various current and voltage data acquisition boards. The proposed system can be used for the calibration of transducers with analog output from DC up to tens of kilohertz and allows the comparison of signals of different kind and order of magnitude.
Metering accuracy is of essence in interconnections between Distribution and Transmission network... more Metering accuracy is of essence in interconnections between Distribution and Transmission networks, in order to ensure market correctness; all components of measurement chains, from instrument transformers to meters, must therefore be calibrated ...
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Papers by Paolo Mazza