Brian Azzopardi

Dispersed Generation Enable Loss Reduction and Voltage Profile Improvement in Distribution Network—Case Study, Gujarat, India

Distribution system operators are often challenged by voltage regulation problems, energy losses, and network capacity problems. This paper analyses a real-life 3.9-MVA distribution network in Gujarat State, India. Distributed generation from renewable energy sources like wind and solar, at optimal locations on distribution feeders, may enable energy loss reduction and voltage profile improvement. A methodology is developed and presented for deciding the appropriate location of these embedded renewable generators. Simulations are performed to calculate different scenarios, and the final analysis reveals that the low voltage problem has totally been eliminated on all of the nodes of the distribution network. Complimentary, significant energy loss reductions are also achieved in the distribution, and the network reserve capacity has also increased.

Smart integration of future grid-connected PV systems

Up until now smart integration of grid-connected photovoltaic (PV) systems is a concept that has been neglected in part due to the availability of subsidies. These subsidies given under different forms of national incentive schemes have made PV the fastest growing energy source in the last few years. In the future, as direct financial incentives and other types of subsidies to PV systems are gradually phased out, smarter grid interface will become an essential feature of future PV systems design. This paper therefore explores future design issues, under dynamic export tariffs in which the objective is to minimize financial costs and maximize revenues for the domestic user, as a net electricity buyer or seller. The analysis model developed applies Mixed Integer Programming time-series simulation. The current typical scenario is depicted with recent time-series of electricity prices used as export tariffs under different household load categories within a UK climate setting. The results suggest that energy storage in a PV system still has only a marginal benefit under smart grid interface. Furthermore with smart integration of PV systems, the micro level objective to minimize costs while maximizing revenue will be achieved with much lower PV module efficiencies. This analysis provides an important insight into PV micro-generator system behavior and the potential for growth of the market for emerging lower cost and lower efficiency PV devices.

Cost boundaries for future PV solar cell modules

Growth of the photovoltaic (PV) market is still constrained by high initial capital costs of PV. Developments in PV technologies may lead to cheaper systems at the likely expense of life expectancy and efficiency. Cost boundaries are required for future PV technologies to compete effectively within the current PV market. This paper develops a methodology based on life-cycle costing and sensitivity analysis to determine cost boundaries for new PV technologies. Amongst other comparisons with existing PV systems, the upper wattpeak cost bounds are estimated and the minimum economically viable replacement period is illustrated. Furthermore, future PV system ratings are compared to current PV systems for similar energy outputs. The results show that a price reduction factor greater than 5 is competitive for future solar cell lifetimes of less than 4-5 years. Meanwhile, future PV systems were, on balance, found to have higher ratings compared to current PV systems of similar energy outputs. The potential application of the model developed in this work is also discussed.

Analysis of renewable energy policy impacts on optimal integration of future grid-connected PV systems

The optimal integration of future grid-connected PV systems will become essential as developments in solar cell technology lead to cheaper PV devices. Moreover as direct financial incentives and subsidies to PV systems are gradually phased out; cheaper PV devices, developed at the likely expense of life expectancy and efficiency, may prevail. This paper presents a model that can be applied to optimize the annual micro-level objectives, that is, to minimize financial costs and maximize revenues for the domestic user. This is essentially a multi-objective optimization problem whose most feasible solution is derived using the weighting method. A case study is presented under different energy pricing and market scenarios which demonstrates the potential of future cheaper PV systems in the context of future renewable energy policies.

Estimation of slip ratio and road characteristics by adding perturbation to the input torque

Electric Vehicles (EVs) present several characteristics which can greatly enhance the performance of the vehicle stability control. The torque response is fast and precise, the wheel speed can be easily estimated and the small dimensions of the motors allow mounting of multiple motors on the same vehicle, each one driving a single wheel. Taking advantage of such characteristics will allow a standard motor controller to integrate feature such as traction-control system (TCS), anti-lock braking system (ABS) and direct yaw control (DYC). This paper presents a novel technique to estimate both the slip ratio and the road friction characteristic without any hardware outside a standard motor controller. Such technique is unaffected by external forces acting on the vehicle. It works by adding a small oscillation to the set torque and then measuring the gain and the phase shift of the wheel speed oscillation. These values can be correlated to the transfer function obtained linearising the vehicle model around an operating point, which is function of the slip ratio and the road characteristics. A SIMULINK simulation is used to validate the method.

Steep increases in biomass demand: the possibilities of short rotation coppice (SRC) agro-forestry

AbstractAt current usage levels, short rotation coppice (SRC) biomass could be considered as an untapped resource. There is a worldwide interest to extend its sustainable production significantly in a decade to come. However, the cultivation of energy crops is very site-specific and the exploitation of SRC biomass is a relatively new trend in biomass application for heat and power production with little information on its cultivation patterns and appropriate combustion technologies. In fact, documented biomass conversion technologies’ impacts in the energy sector and their commercialisation are limited. This paper aims to present a summary of technical characteristics for different biomass conversion technologies. These characteristics are not necessarily unique to all types and possible modifications of the biomass conversion technologies applied for many countries. However, the lack of technical knowledge have created situations that were previously impossible to be solved without the aid of numerous re...

Green Energy and Technology: Choosing Among Alternatives

The primary renewable energy system (RES) investment decision-making criteria are economics. These criteria are focused on the RES and its support ancillary infrastructure technical superiorities, such as efficiency and cost, which is reasonable in the context of generous financial support schemes. However, when financial supports are phased out the energy market becomes technologically diversified environmental, political and social concerns, which include both quantitative as well as qualitative criteria, become significant. The technical superiorities may fail to describe RES or the relevant technology properly. This chapter is structured in two parts. Firstly, the available knowledge with regards to the general decision making processes is described, followed by a critical perspective about today’s decision making. The second part presents a review of three enhanced approaches using Real Options Theory, Multi-Criteria Decision Analysis and Multi-Criteria Cost Benefit Analysis which are applied to RES decision making both from the personal or investment point of view as well to the policy and the latter pan-European point of view. Finally, the society challenges are discussed within this context.

Flexible economic load dispatch integrating electric vehicles

Incorporation of Electric Vehicles (EV) into power grids may pose serious challenges on secure operation of the system. Thus, the conventional ED problem required reformulation, encompassing EVs operational constraints. As a result, ED-EV algorithm can be established, that minimizes total dispatch costs while taking into account a plethora of intertemporal and spatial constraints over a short-term execution. Simulation results exhibited that the proposed ED-EV effectively improves total dispatch costs with a technically-sound use of generation sources in the system. However, an auspicious shift in generation strategies facilitates relieving peak-hours load through the EVs dual operational modes (charging/discharging). Further, the obtained results represented that employing Newton Raphson (NR) load flow instead of an approximated loss technique can procure an accurate and further money-saving solution. Based on the simulations, the integration of the EVs into the grid can immensely enhance the socio and techno-economic aspects of the system operation.

Improving Lagrangian Relaxation Unit Commitment with Cuckoo Search Algorithm

In many utilities, it is essential to devise an optimum commitment solution of generating units for better operational efficiency, under empirical conditions. Among the methods reported in the technical literatures, Dynamic Programming (DP), Lagrangian Relaxation (LR), and Mixed-Integer Programming (MIP) are the most industry proven algorithms in the line of business. This paper improves the available solution offered in LR technique, which was mainly suffered from high fluctuation of duality gap between the primal and dual solutions. As a remedy, a Cuckoo Search Algorithm (CSA) is proposed to optimize the gap progress throughout the LR solution process. Simulation results reiterate that the developed LR-UC integrating CSA enhances the solution quality.