Impact of hybrid renewable energy systems on short circuit levels in distribution networks

The effects of the distributed generation can be classified as environmental, technical and economical effects. It is playing a very vital role for improving the voltage profiles in electrical power systems. However, it could have some negative impacts such as operating conflicts for fault clearing and interference with relaying. Distribution system is the link between the utility system and the consumer. It is divided into three categories radial, Loop, and network. Distribution networks are the most commonly used to cover huge number of loads. The power system reliability mainly depends on the smooth operation and continuity of supply of the distribution network. However, this may not always be guaranteed especially with the introduction of distributed generation to the distribution network. This paper will examine the impact of hybrid renewable energy systems (using photovoltaic and doubly fed induction generators) on short circuit level of IEEE 13-bus distribution test system using ETAP software

Evaluation of the implementation process of urban road pricing schemes in the United Kingdom and Italy

This paper is based upon detailed research that has taken place in the UK and Italy, on the implementation strategies for urban road pricing schemes. In the UK, both in London and Durham, the Road User Charging schemes required new legislation, and were implemented rapidly. The time from announcement to implementation took three years and the schemes were introduced after short periods of intensive planning, consultations and stakeholder networking. In Italy, the situation has been very different. The road pricing schemes in Rome and Genoa were not introduced under specific legislation but rather evolved from access control zones originally implemented in historic urban centres. The incremental introduction of the Italian road pricing experiments has taken approximately ten years. The paper undertakes a comparison of these different strategies to introduce urban road pricing and the lessons they contain for the development of similar measures elsewhere. The comparison of the different implementing experiences is undertaken using Strategic Policy Niche Management, a method designed to explore, among other factors, the dynamics of the stakeholder networks involved in planning, introducing, marketing and managing radical urban Travel Demand Management policies

The Role of Digital Technology and Regulations in the Diffusion of Mobile Phones in Asia

More and more people are using mobile (cellular) phones and the world is increasingly becoming unwired due to diffusion of this technology. The cellular technology is present in most Asian countries since 1980s. However, its diffusion process in these countries has largely been affected by technological developments, i.e., transition from analogue to digital, and regulations. The nature of regulations relate to spectrum licensing and the number of competitors allowed by respective governments. These regulatory decisions may explain the current structure of mobile phone industry in most of these countries. The popularity of cellular communication lies in its appealing advantage as compared with the fixed networks. The most important feature of a cellular phone is its portability in that the call is made to a person and not to a place. In developed countries, the features available on mobile handsets (such as caller line identification, voice mail, call forwarding, call waiting and the facility of receiving and transmitting short text messages) are available free of charge. However, these cell phone facilities are very costly in developing countries as compared with their fixed networks. The regulatory licensing structure prevailing in these countries partly explains this price differential. In effect there has been wide diversity in the speed of introduction of mobile phones and their diffusion across developing countries, which has not been explored. Gruber and Verboven (1998) has recently examined diffusion of cell phones in the European Union. However, this is a neglected area of research in developing countries.

Economic incentive patterns and their application to ad hoc networks

While research about cooperation incentives for mobile ad hoc networks (MANETs) is done only for a relative short period, there exists tremendous knowledge in the economic and social areas. Based on a new categorization of incentive patterns, we examine the relevant properties of each pattern and demonstrate their respective design alternatives and occurring challenges for the application to ad hoc networks. With a focus on trade based patterns, we found that negotiation about actions proves to be very complex or inefficient in MANETs. Another approach, the introduction of an artificial currency, also implies several problems like how to equip the entities with means of payment and how to secure liquidity. As a novelty, we introduce a new kind of incentive pattern following the concept of company shares. It suits well for MANETs because it can be shown that through the creation of individual currencies the above mentioned problems disappear

Robust rolling stock under uncertain demand in rapid transit networks

This paper focuses on the railway rolling stock circulation problem in rapid transit networks where the known demand and train schedule must be met by a given fleet. In rapid transit networks the frequencies are high and distances are relatively short. Although the distances are not very large, service times are high due to the large number of intermediate stops required to allow proper passenger flow. The previous circumstances and the reduced capacity of the depot stations and that the rolling stock is shared between the different lines, force the introduction of empty trains and a careful control on shunting operation. In practice the future demand is generally unknown and the decisions must be based on uncertain forecast. We have developed a stochastic rolling stock formulation of the problem. The computational experiments were developed using a commercial line of the Madrid suburban rail network operated by RENFE (The main Spanish operator of suburban trains of passengers). Comparing the results obtained by deterministic scenarios and stochastic approach some useful conclusions may be obtained

Bio-inspired ant colony optimization based clustering algorithm with mobile sinks for applications in consumer home automation networks

With the fast development of wireless communications, ZigBee and semiconductor devices, home automation networks have recently become very popular. Since typical consumer products deployed in home automation networks are often powered by tiny and limited batteries, one of the most challenging research issues is concerning energy reduction and the balancing of energy consumption across the network in order to prolong the home network lifetime for consumer devices. The introduction of clustering and sink mobility techniques into home automation networks have been shown to be an efficient way to improve the network performance and have received significant research attention. Taking inspiration from nature, this paper proposes an Ant Colony Optimization (ACO) based clustering algorithm specifically with mobile sink support for home automation networks. In this work, the network is divided into several clusters and cluster heads are selected within each cluster. Then, a mobile sink communicates with each cluster head to collect data directly through short range communications. The ACO algorithm has been utilized in this work in order to find the optimal mobility trajectory for the mobile sink. Extensive simulation results from this research show that the proposed algorithm significantly improves home network performance when using mobile sinks in terms of energy consumption and network lifetime as compared to other routing algorithms currently deployed for home automation networks