A novel procedure for estimating the total inertia of the Great Britain (GB) power system is presented. Following an instantaneous in-feed loss, regional variations in the estimate of inertia are obtained from measured frequency transients using installed synchronised phasor measurement units (PMUs). A method is proposed to first detect a suitable event for analysis, and then filter the measured transients in order to obtain a reliable estimate of inertia for a given region of the GB network. The total inertia for the whole system is then calculated as a summation, with an estimate also provided as to the contribution to inertia from residual sources, namely synchronously connected demand and embedded generation. The approach is first demonstrated on the full dynamic model of the GB transmission system, before results are presented from analyzing the impact of a number of instantaneous transmission in-feed loss events using phase-angle data provided by PMUs from the GB transmission network and also devices installed at the domestic supply at 4 GB universities.

A strategy for volt/VAr control in distribution systems is described. The aim is to determine optimum dispatch schedules for on-load tap changer (OLTC) settings at substations and all shunt capacitor switching based on the day-ahead load forecast. To reduce switching operations for OLTC at substations, a time-interval based control strategy is adopted that decomposes a daily load forecast into several sequential load levels. A genetic algorithm based procedure is used to determine both the load level partitioning and the dispatch scheduling. The proposed strategy minimises the power loss and improves the voltage profile for a whole day across the whole system, whilst ensuring that the number of switching operations is less than the maximum daily allowance. A comparison of numerical studies and their associated results illustrates both the feasibility and the effectiveness of the proposed strategy.

Photovoltaic (PV) generation involves the direct conversion of sunlight into electrical energy. In recent years it has proved to be a cost-effective method for generating electricity with minimum environmental impact. Due to the environmental and economic benefits PV generation is now being deployed worldwide as an embedded renewable energy source and extensive research is being performed in order to study and assess the effectiveness of PV arrays in Distributed Generation (DG) systems either as a potential energy source or as energy reserve in combination with other types of distributed energy resources. This paper presents the modeling and MATLAB simulation of a stand-alone polycrystalline PV Array system and investigates load following performance efficiency under various loading and weather conditions as well as suitability with regard to enhancing power supply reliability to critical loads. The modeling of the PV array that has been performed in this research using MATLAB Simulink is based on the calculation of parameters for the Thevenin's equivalent circuit of each cell of the array. The standard double exponential polycrystalline cell model has been adopted for this research with solar irradiance E and ambient temperature T as the input and Thevenin's voltage V_thar and Thevenin's resistance R_thar as the output.