A PMU for the Measurement of Synchronized Harmonic Phasors in Three-Phase Distribution Networks

Owing to the extension of electric distribution networks, monitoring and control issues rely on large-scale distributed measurement systems, which are able to carry out simultaneous measurements of electrical quantities in several points of the monitored systems. In this paper, the implementation of digital procedures that are suitable for the evaluation of the synchronized harmonic phasors in a flexible phasor measurement unit (PMU) based on PXI modular hardware is presented. The results of the experimental tests are shown to characterize the measurement system to evaluate the behavior of the designed instrument under real operating conditions on three-phase electric distribution networks.

I. Introduction

Nowadays, electric distribution systems are involved in a continuously growing penetration of distributed generation (DG) plants. The increase in the number of these plants, which are often based on renewable energy sources, involves a significant impact in terms of management, regulatory, reliability, and technical issues [1]. At the same time, in the liberalization of the energy market, the quality of the product provided by the utilities can be a critical competitive item and can represent a clause in contracts for supplying energy to the customers. As a consequence, suitable measurement methodologies have to be implemented to identify the sources of power quality disturbances, such as harmonic distortion [2], [3]. The information achieved should sufficiently be reliable since it can provide directions on tariffs, as well as on the system management.