Influencing Factor and Error Analysis of Operating Capacitor Voltage Transformer Harmonic Measurement

With the increasing demands of power quality monitoring and management, the problem of harmonic measurement error caused by the widespread operation of capacitor voltage transformers (CVT) in high-voltage power grids has been unavoidable. This paper analyses the influence of environmental factors on harmonic measurement error of CVT, and proposes a new method for analysing the harmonic measurement errors of operating CVT, which explains the unstable phenomenon of CVT measurement errors based on field comparison test, and provides a progressing screening method of effective analysis data. the CVT harmonic error characteristic analysis method proposed in this paper considers the impact of field installation conditions, electromagnetic environment, and other actual operating environment, which can reflect the actual harmonic error characteristics of CVT in field operation. A CVT harmonic measurement system is established based on the proposed method. The validation and effectiveness of the proposed method is illustrated on a field measurements of 1000kV CVT in Shandong Province.

Designing a system to synchronize the input signal in a telecommunication network under the condition for reducing a transitional component of the phase error

The quality of reception, as well as the processing and demodulation of the input signal in the telecommunication systems' networks, are closely related to the quality indicators in the functioning of one of the subsystems of these networks, namely a phase synchronization system. This work has directly considered the issues related to improving the performance and reducing the transitional component of the phase error generated by transition processes in the combined synchronization system. A mathematical model has been built that makes it possible to synthesize a disrupted link in the synchronization system of a telecommunication network meeting the condition for a decrease in the transitional component of the phase error. It is shown that a simple disrupted link, synthesized under the condition of suppressing a slow-fading transition component, makes it possible to shorten the time of the transition process in the system while maintaining the initial order of astatism. When a complex link is synthesized, the transition process becomes oscillatory. It was established that under the conditions of a phase jump or a frequency jump, it is possible to improve the dynamics of the system and reduce the transitional component of the phase error variance by making the parameters for the disrupted communication link influence the roots of the characteristic equation of the transition process. The features in synthesizing disrupted communication have been considered for the intervals of movement corresponding to areas with the positive and negative inclination of the phase discriminator's static characteristic. Such conditions have been devised that make it possible to determine the value and sign of the root in the characteristic equation of the transition process, which is introduced by the parameter of a disrupted communication link separately for areas of the stable and non-steady movement of the phase discriminator's static characteristic. The reported mathematical model of disrupted link synthesis has made it possible to derive reference results. They indicated that in order to suppress the slowly fading component of the phase error characteristic equation to "0", it is necessary to provide for a significant advantage, up to 10 times, of the roots introduced by the disrupted communication link over the roots of the specified component. By changing the value for a disrupted communication parameter, one can significantly, up to 5 times or larger, shorten the time of the transition process in the combined synchronization system at a simultaneous decrease of 18‒25 % in the initial value of the transition error

Error Characteristic Analysis of Fluid Momentum Law Test Apparatus

The flat-plate momentum test bench is a widely used experimental device in the verification of the momentum law of fluid mechanics, and its error characteristics are of positive significance for theoretical research and engineering innovation and expansion. The SPH-FEM coupling algorithm and spectrum analysis method are used to calculate and analyze the displacement response and spectrum characteristics of the characteristic points of the sensor under different jet loads. Based on them, the cause, classification, law, scope, influence and control method of the measurement error of the system are discussed and analyzed with the application of the error theory and the lateral effect theory of strain gauges; combined with physical experiments, the relevant analysis methods and conclusions are verified. The results show that the measurement error of the system includes linear error and periodic error. Structural deformation in the direction of jet impact is the main source of linear error; linear error increases with the increase of jet loads. Meanwhile, periodic vibration in non-jet direction is the main cause of periodic error, and the periodic error decreases with the increase of jet loads.

AVERAGE DERIVATIVE ESTIMATION UNDER MEASUREMENT ERROR

In this paper, we derive the asymptotic properties of the density-weighted average derivative estimator when a regressor is contaminated with classical measurement error and the density of this error must be estimated. Average derivatives of conditional mean functions are used extensively in economics and statistics, most notably in semiparametric index models. As well as ordinary smooth measurement error, we provide results for supersmooth error distributions. This is a particularly important class of error distribution as it includes the Gaussian density. We show that under either type of measurement error, despite using nonparametric deconvolution techniques and an estimated error characteristic function, we are able to achieve a $\sqrt {n}$ -rate of convergence for the average derivative estimator. Interestingly, if the measurement error density is symmetric, the asymptotic variance of the average derivative estimator is the same irrespective of whether the error density is estimated or not. The promising finite sample performance of the estimator is shown through a Monte Carlo simulation.