Diwakar Bista

Nepal houses many traditional and cultural sites rich in historical cultural diversity. These sites are also economically important to the nation. These monuments show the culture and the living beliefs of the communities; hence, people from all over the world are attracted to such place to observe the beauty and to feel the spirit and the conservational perspectives behind these articulated edifices. In today’s context, artificial light is a basic necessity for human activities and has been used in various applications: one such application being night-time illumination of historical sites and monuments. Most of the historic monuments in Nepal were constructed during the 15th to 18th century and are designed to incorporate oil-based wick lamp as the light source. Recently with the availability of modern luminaires and lack of technical expertise and scientific approach, most of the historic sites are being filled up with uneven, exaggerated, and inappropriate illumination. This inappropriate illumination practice may lead to negative consequences that may create disturbance to human and the surrounding environment. Scope of this paper is to identify the special needs for illuminating cultural and heritage sites with Pagoda-style architecture and introduce a methodology for a case study in Nepal. As a first step, this paper analyzes lighting malpractices in the temples of Nepal at different geographical locations and cultural values. As a next step, a prototype LED luminaire that enhances the unique type of architecture of Nepalese heritage sites was built, installed, and demonstrated in one of the temples. The work presents the design process of the lighting system and the results of a new lighting installation. The study also discusses possible problems that may arise while designing lighting for cultural and heritage site and provides recommendations on considerations to be taken during the design.

Hybrid Power System (HPS) is an energy system with combination of different regenerative energy sources like Solar, Wind, Geo-Thermal, Biomass and several others to achieve energy sustainability. This paper investigates the feasibility of grid connected and stand-alone hybrid energy system to meet electric load requirement of a community or organization, by utilizing the available resources. Potentiality of different energy sources like solar, wind, bio-gas, etc. along with currently used energy sources is studied thoroughly by taking a case study of Kathmandu University central campus, located at Dhulikhel, Nepal. Technical and economic analysis of on-grid and off-grid hybrid system is performed to get optimum model that supply continuous energy to the end user. Furthermore, the possibility of net metering with national utility has been analysed. The main objective of this study is to identify the suitable energy mixed model, that provide the sustainable energy supply to the university, and recommend the possible energy generators to be added for fulfilling the continuously increasing load demand. The load profile of several years of the University is taken into consideration for forecasting the power demand. The findings of the research show that system when adopted to hybrid system can meet up to 55% of the load by renewable resources. Maximum renewable fraction is found to be 0.603 and maximum renewable penetration of 812%.

The issue of unintentional islanding in grid interconnection still remains a challenge in grid-connected, Distributed Generation System (DGS). This study discusses the general overview of popular islanding detection methods. Because of the various Distributed Generation (DG) types, their sizes connected to the distribution networks, and, due to the concern associated with out-of-phase reclosing, anti-islanding continues to be an issue, where no clear solution exists. The passive islanding detection technique is the simplest method to detect the islanding condition which compares the existing parameters of the system having some threshold values. This study first presents an auto-ground approach, which is based on the application of three-phase, short-circuit to the islanded distribution system just to reclose and re-energize the system. After that, the data mining-decision tree algorithm is implemented on a typical distribution system with multiple DGs. The results from both of the techniques have been accomplished and verified by determining the Non-Detection Zone (NDZ), which satisfies the IEEE standards of 2 s execution time. From the analysis, it is concluded that the decision tree approach is effective and highly accurate to detect the islanding state in DGs. These simulations in detail compare the old and new methods, clearly highlighting the progress in the field of islanding detection.