Ali Rifat Boynuegri

Static Modeling of Microgrids for Load Flow and Fault Analysis

Inverter interfaced distributed generators (DGs) in microgrids have different characteristics and models that are not available in the existing conventional power flow analysis tools. This paper presents a static modeling approach for inverter interfaced DGs that can be applied for time spread load flow analysis and fault analysis of microgrids, including droop-based voltage controlled DGs. The static models have been derived from the common control schemes applied to inverter interfaced DGs, including the constraints emerging from droop control and reflect steady-state behaviors of inverters accurately. In addition to simplification of analysis procedure, the static models can provide a base for the analysis of microgrids with conventional numeric analysis tools. The presented static modeling approach has been validated comparatively with the dynamic modeling results of a test microgrid.

Smart insular grids: Opportunities and challenges

The ever increasing environmental concerns together with depletion risk of conventional fossil fuels that can threat the energy independence of energy importing countries have led to more interest in renewable energy sources of locally produced energy. Increase in such sources together with new types of integrated loads has required new concepts to operate bulk electricity power grid. Accordingly, a relatively new concept - the smart grid - has been widely publicized recently with huge investments of both developed and developing country governments in this area. The smart grid concept is currently in the test phase and insular grids have been generally considered as one of the most suitable structures to evaluate the applicability of “smart” solutions. Thus, the general structure and applicable smart grid based strategies are presented in this study to promote the overall operating performance of such systems. The opportunities as well as the possible challenges of smart solutions are discussed, and the future requirements are evaluated.

A non-intrusive system for measuring underground power utility cable impedance

It is shown that impedance measurements can be used to quantify transmission line damage. A device design is given for detecting the complex impedance of a transmission line at high frequencies without disrupting regular service. A complementary device is presented that simulates an open circuit at the excitation frequency at some distance from the excitation source, thus increasing the sensitivity of the impedance measurement. Experimental verification data from a prototype measurement device is presented.