Προβλήματα στην μέτρηση ενέργειας στα δίκτυα

Abstract

Electromagnetic compatibility (EMC) issues in the frequency range within 2 kHz to 150 kHz, also known as supraharmonics, have long been confined to industrial applications. Due to the increasing market volume, for equipment operating at switching frequencies above 2 kHz, cases of (unintentional) supraharmonic transmission on low voltage public grids have significantly increased over the last decade. Parts of the frequency range which was mentioned above are also used in many countries as a means of communication by utilizing the power line (PLC) for electricity measurement (intentional transmission). Therefore, interference can occur not only between devices with intentional transmission, but also PLC devices and applications. An increasing number of interferences that are related to the Supraharmonic Frequency Range have led to the need for further investigation into the malfunction of various equipment. This study focuses on the systematic errors that manifest in measurement arrangements, and especially in smart metering devices. The purpose of this study is to highlight the impact of supraharmonics that appear with increasing frequency in low voltage grids and especially in measurement arrangements. Another purpose is to demonstrate the fault of representation in existing archetypes for the frequency range 2-150 kHz. In order to achieve this, the first chapter of this study focuses on the description of safety arrangements and standardization of low voltage grids. The second chapter touches upon the European and national politics for the transition to smart grids. The features and advantages of smart grids are also presented. The third chapter focuses on the operation, the technical features and measurement technology for the various measurement devices, as well as on presenting of the digital meters of Hellenic Electricity Distribution Network Operator. In the fourth chapter the theory of various errors, including their mathematical background is presented, as is the way that they are applied in measurement arrangements. The fifth chapter analyzes the terms of power quality, electromagnetic compatibility, and its impact on operating conditions. Moreover, the standard trends of the measurement of harmonic deformations are analyzed. Last, the final two chapters of this study include an analysis of supraharmonics, their impact and electromagnetic interference. Furthermore, they include the most important part of this research that refers to the optimization of existing archetypes and the issues that arise for the measurements in the frequency range 2-150 kHz.