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The era of Renewable Energy sources has overtaken the usage of conventional energy sources like coal, fossil fuels etc. This paper presents grid interface of single phase transformerless inverter system using enhanced phase locked loop. To connect solar PV with grid it is required to estimate phase angle, voltage amplitude and phase angle measurement of grid and the output of inverter. It is required to track exact utility voltage vector for reliable control of power to the grid. This paper compares the frequency measurement and phase angle and voltage amplitude using simple phase locked loop system along with enhanced phase locked loop so that the enhanced phase locked loop (EPLL) is proved to be giving superior performance over simple phase locked loop. The simulation of both the techniques are pursued and the results are compared.

U radu je razvijeno sklopovlje i programska potpora mjernog sustava za kontinuirano praćenje strujno-naponskih odnosa u gradskoj mreži. Sustav omogućuje mjerenje efektivne vrijednosti struje i napona te mjerenje faznog odnosa između tih dviju veličina. Mjerni sustav temeljen je na mikrokontroleru STM32H745 za upravljanje periferijskim sklopovljem i obradu signala, strujnom senzoru ACS725 i mjernom transformatoru ZMPT107-1. U sustav je uključen dodatni mikrokontroler ESP8266EX koji služi za povezivanje sustava s Wi-Fi mrežom i prikaz mjernih rezultata putem lokalnog web servera, a s glavnim mikrokontrolerom se povezuje putem UART komunikacijskog protokola. Provedena je eksperimentalna verifikacija mogućnosti mjernog sustava te je pokazano da su nesigurnosti mjerenja napona, struja i faznog kuta među njima unutar očekivanih granica. In this thesis the hardware and software needed for a measurement system for continuous monitoring of current and voltage relationships in electrical power grid was developed. The system enables the measurement of current and voltage RMS values and the measurement of the phase relationship between these two values. The measuring system is based on the STM32H745 microcontroller for peripheral control and signal processing, ACS725 current sensor, and ZMPT107-1 measurement transformer. The system includes an additional microcontroller ESP8266EX, which is used to connect the system over a Wi-Fi network and to display measurement results via a local web server. The additional microcontroller is connected with the main microcontroller via a UART communication interface. An experimental verification of the measuring system capabilities was performed and it was shown that the measurement uncertainties of the voltage, current and phase angle measurements are within the expected limits.

This paper deals with the evaluation of the accuracy performance of an approach for assessing the phase displacement between voltages at power network nodes. This task is accomplished by processing asynchronous measurements taken at each node. This turns into an equivalent synchronization, which is, therefore, obtained without exploiting any synchronization signals, such as the ones provided by means of wireless (i.e., global positioning system) or wired technologies. As a matter of fact, distribution system operators will gain the possibility of deploying, at more affordable costs, wide area measurement system (WAMS) over their power networks for enhancing their stability and reliability. Phasor measurement units (PMUs) are the most common examples of such WAMS, but, besides their high cost, there are circumstances where providing a time reference signal to remote PMUs often becomes a difficult task. This paper aims at recalling the basic theoretical principles of the method and at proving its applicability in power network through a deep analysis of its metrological performance.

A time constant standard, developed for the phase angle measurement of precision current shunts is developed and described, and its time constant has been determined. Based on a single circular loop placed in an air thermostat, its construction is very simple and it gives accurate results in the frequency band of interest, e.g. for frequencies between 50 Hz and 100 kHz. The influence of the shielding is calculated using numerical Finite Element Analysis (FEA). The thermostatic stability is analyzed, and the time-constant of the thermostat is determined using temperature measurement and Butterworth filtering. The power coefficient of the standard is determined, and limits of errors are discussed.

The paper presents a novel mathematical approach for assessing the phase angle displacement of voltages at nods of a power network with respect to a node taken as reference. It is accomplished without the use of a global time-reference signal, like those provided by GPS technology or through wired connections. This study origins from the growing interest of Distribution System Operators (DSOs) to deploy Distributed Synchronized Measurement Systems (DSMS) in their power networks (like, in particular, the Phasor Measurement Units) for enhancing the stability and reliability of the networks. There are circumstances where bringing a time reference signal to remote PMUs is a difficult task. The paper provides an alternative solution to evaluate phasors in Distribution lines with no need of a global time reference.

This paper deals with the problem of synchronizing phasor measurements in different nodes of a power network. Usually, this issue is faced by using a synchronization signal provided by wired or wireless communication infrastructure. As it is well known, the most common implementation of such a solution is the so-called Phasor Measurement Unit (PMU) which relies on a time reference signal coming from the GPS system. In this work, an alternative approach based on asynchronous measurements is presented and discussed. In particular, it is firstly shown how an equivalent synchronization among different nodes can be obtained by performing voltage and current measurements in all the nodes of the considered network. After that, an equivalent synchronization when only 75% of the nodes are monitored, is presented.