Control and protection of a microgrid connected to utility through back-to-back converters

This paper discusses the control and protection of a microgrid that is connected to utility through back-to-back converters. The back-to-back converter connection facilitates bidirectional power flow between the utility and the microgrid. These converters can operate in two different modes–one in which a fixed amount of power is drawn from the utility and the other in which the microgrid power shortfall is supplied by the utility. In the case of a fault in the utility or microgrid side, the protection system should act not only to clear the fault but also to block the back-to-back converters such that its dc bus voltage does not fall during fault. Furthermore, a converter internal mechanism prevents it from supplying high current during a fault and this complicates the operation of a protection system. To overcome this, an admittance based relay scheme is proposed, which has an inverse time characteristic based on measured admittance of the line. The proposed protection and control schemes are able to ensure reliable operation of the microgrid.

Fault isolation in distributed generation connected distribution networks

Protection of a distribution network in the presence of distributed generators (DGs) using overcurrent relays is a challenging task due to the changes in fault current levels and reverse power flow. Specifically, in the presence of current limited converter interfaced DGs, overcurrent relays may fail to isolate the faulted section either in grid connected or islanded mode of operation. In this paper, a new inverse type relay is presented to protect a distribution network, which may have several DG connections. The new relay characteristic is designed based on the measured admittance of the protected line. The relay is capable of detecting faults under changing fault current levels. The relay performance is evaluated using PSCAD simulation and laboratory experiments.

Power relations and small and medium-sized enterprise strategies for capturing value in global production networks: visual effects (VFX) service firm in the Hollywood film industry

Power relations and small and medium-sized enterprise strategies for capturing value in global production networks: visual effects (VFX) service firms in the Hollywood film industry, Regional Studies. This paper provides insights into the way in which non-lead firms manoeuvre in global value chains in the pursuit of a larger share of revenue and how power relations affect these manoeuvres. It examines the nature of value capture and power relations in the global supply of visual effects (VFX) services and the range of strategies VFX firms adopt to capture higher value in the global value chain. The analysis is based on a total of thirty-six interviews with informants in the industry in Australia, the United Kingdom and Canada, and a database of VFX credits for 3323 visual products for 640 VFX firms.

Trust, reputation and the small firm : building online brand reputation for SMEs

Social media provides numerous opportunities for small businesses to promote their products and services, build brand communities and reach diverse market niches. An important factor in seizing these opportunities is developing trust and creating reputation among consumers. This qualitative study examines how a group of Australian small business managers utilize social media websites to connect to, communicate with and maintain their customer base. For the purpose of this paper we are using case studies of four companies physically based in Victoria, Australia. These businesses have a high presence in online consumer groups, being both active members of communities and representatives of their businesses. The duality of their role as participant and company representative imposes difficulties in creating reputation among community members. We have used in-depth interviews as a primary research method, additionally monitoring their activities on social media sites such as forums, social networking services, blogs and micro-blogs. We have identified practices helpful for developing trust, building reputation and create a brand image in online communities.

New exact solutions for Hele-Shaw flow in doubly connected regions

Radial Hele-Shaw flows are treated analytically using conformal mapping techniques. The geometry of interest has a doubly-connected annular region of viscous fluid surrounding an inviscid bubble that is either expanding or contracting due to a pressure difference caused by injection or suction of the inviscid fluid. The zero-surface-tension problem is ill-posed for both bubble expansion and contraction, as both scenarios involve viscous fluid displacing inviscid fluid. Exact solutions are derived by tracking the location of singularities and critical points in the analytic continuation of the mapping function. We show that by treating the critical points, it is easy to observe finite-time blow-up, and the evolution equations may be written in exact form using complex residues. We present solutions that start with cusps on one interface and end with cusps on the other, as well as solutions that have the bubble contracting to a point. For the latter solutions, the bubble approaches an ellipse in shape at extinction.

The Impact of Information Technology Investments on Firm Processes and Performance

This book provides the much needed international dimension on the payoffs of information technology investments. The bulk of the research on the impact of information technology investments has been undertaken in developed economies, mainly the United States. This research provides an alternative dimension - a developing country perspective on how information technology investments impacts organizations. Secondly, there has been much debate and controversy on how we measure information technology investment payoffs. This research uses an innovative two-stage model where it proposes that information technology investments will first impact the process and improvement in the processes will then impact the performance. In doing so, it considers sectors of information technology investment rather than taking it as one. Finally, almost all prior studies in this area have considered only the tangible impact of information technology investments. This research proposes that one can only better understand the benefits by looking at both the tangible and intangible benefits.

Elementary teacher education in papua new guinea: towards a culturally connected perspective of teaching

Global and national agendas for quality education have led to reforms in Papua New Guinea’s (PNG) elementary education, but criticism of the learner-centred, Western pedagogies has emerged. One key influence on quality teacher education relates to perspectives of teaching. Existing research shows teachers’ beliefs and perceptions of teaching influence their practice, however to date little research has investigated perspectives of teaching for elementary education in PNG. This single exploratory case study investigated the perspectives of teaching for eighteen elementary teacher trainers as they studied for a Bachelor of Early Childhood (Teacher Education). The study, drawing on an interpretivist paradigm, analysed journals and course planning documents using a thematic approach. The findings revealed that while the trainers’ perspectives of teaching children tended to reflect a learning-centred perspective (focused on what the teacher does), their perspectives of teaching adults were both learning-centred and learner-centred (what the learner does). Based on these findings, a culturally connected perspective of teaching is advocated for PNG elementary teacher education. This perspective enables the co-existence of both the learning-centred and learner-centred perspectives of teaching in the PNG cultural context and has implications for teacher education and the communities involved in elementary education in general.

Four years on – are the Gazelles still running? A longitudinal study of firm performance after a period of rapid growth

Gazelles, or very rapidly growing firms, are important because they contribute disproportionately to economic growth. There is a concern that some of these firms pursue growth too aggressively resulting in lower subsequent performance. We investigate the relationship between growth and subsequent profitability for gazelle firms, and how this is moderated by firm strategy. Previous empirical research regarding the growth-profitability relationship for firms in general is rather inconclusive, with only one study specifically investigating gazelle firms. Likewise, there are theoretical arguments both for and against growth leading to profitability that equally apply to gazelle firms. Further, while contingency theory might suggest the relationship depends on the firm’s strategy, earlier studies have not investigated this relationship. We address these questions using longitudinal data (seven years) for a sample of 964 Danish Gazelle firms. Our study finds a clear positive relationship between growth and subsequent profitability among gazelle firms. Moreover, this relationship is stronger for firms pursuing a broad market strategy rather than a focus or niche strategy. An important managerial implication is that the growth strategy should be clearly integrated with the general strategic orientation of the firm.

An Econometric Analysis of Inter-Firm Labour Mobility

This paper utilizes the Survey of Work History (1981) data to examine the importance of non-random sampling in the context of a model of interfirm labour mobility. The paper adopts Heckman's two-step procedure in order to estimate a three-equation model incorporating an individual's mobility status as endogenously determined. The main conclusion is that in estimating wage equations it is important to consider the role of job mobility and to correct for the effects of sample-selection bias. The results generally accord with those reported by Osberg et al. (1986) in the only previous Canadian study of job mobility in a sample-selection context.

Multiple founders and firm value

In this paper, we highlight the existence of multi-founder firms, which were founded by multiple individuals (with no family connections) who are still actively involved in the firm as directors and/or managers. These firms provide a unique setting to shed further light on the net valuation effects of founder involvement. In particular, multi-founder firms provide us with the opportunity to examine the benefits and costs to shareholders of multiple founders involved as directors, CEOs and managers in the same firm. Our analysis indicates that multi-founder firms are more valuable than all other types of firms, including single-founder firms and family firms, with the valuation premium positively related to the number of founders involved in the firm. Further analysis confirms that this valuation premium is linked to the direct involvement of the multiple founders as directors and CEOs. However, further founder involvement in vice president positions has a negative relationship with firm value.

Waving or drowning? Managing resource constraints in entrepreneurial firm with bricolage as a response to the global financial crisis

These are challenging times for new entrepreneurial firms. The development of the Global Financial Crisis shook the very foundations of global markets and institutions that most firms relied on to do business (Claessens, et al., forthcoming). In the midst of institutional flux and resource constraints, entrepreneurial firms, which have been shown to make a range of contributions to the economy (van Praag & Versloot 2007) faced increasing constraints. The Australian Federal Government quickly implemented the Green Loan program in response to the financial crisis. Unfortunately, the green loans program was flawed with obsolete processes and information (Faulkner, 2011), further constraining new firms. Prior research provides few clues regarding how resource-constrained entrepreneurial firms deal with these institutional flaws within institutional change and how they might overcome these challenges and prosper. One promising theory that evaluates behavioural responses to constraints and institutional flaws is bricolage (Levi Strauss, 1967). Bricolage aligns with notions of resourcefulness: defined here as “making do by applying combinations of the resources at hand to new problems and opportunities” (Baker and Nelson 2005: 333). Using three case studies, we consider how institutional flaws impact firm behaviours and illustrate the use of bricolage in attempts to reinforce, shape and change the GL program further extending bricolage domains of Baker and Nelson (2005).

The relationship between firm survival and innovation : an introduction to the literature

The rapid growth in use of the Internet as a business tool provides a new perspective in the study of the organizational challenges of new technologies. The innovation literature has grown vastly since its establishment in the 1920s, covering a broad range of disciplines (Foxall 1984) and measures a wide variety of variables (Rogers 1995). At first glance, studies that look at the relationship between innovation and firm survival appear contradictory. However, the results appear compatible when additional factors, such as industry type, organizational age, company size or the duration of the study are taken into account.