Raymond F. Ghajar

Time-series models for reliability evaluation of power systems including wind energy

Abstract An essential step in the reliability evaluation of a power system containing Wind Energy Conversion Systems (WECS) using sequential Monte Carlo analysis is to simulate the hourly wind speed. This paper presents two different time-series models generated using different available wind data. Wind data from Environment Canada and SaskPower are used to illustrate these models. No assumptions or previously estimated factors are included in the models. In order to check the adequacy of the proposed models, the F-criterion and Q-test are used, and the statistical characteristics of the simulated wind speeds are compared with those obtained from the actual wind speeds. The proposed wind models satisfy the basic statistical tests and preserve the high-order auto-correlation, seasonal property and diurnal distributions of the actual wind speed.

A sequential simulation technique for adequacy evaluation of generating systems including wind energy

A wind energy conversion system (WECS) has a different impact on the reliability performance of a generating system than does a conventional energy conversion system. This is due to the variation of wind speeds and the dependencies associated with the power output of each wind turbine generator (WTG) in a wind farm. In this paper, a sequential Monte Carlo simulation technique is proposed for adequacy evaluation of a generating system including WECS. The method is based on an hourly random simulation to mimic the operation of a generating system, taking into account the auto-correlation and fluctuating characteristics of wind speeds, the random failure of generating units and other recognized dependencies. The hourly wind speeds are simulated utilizing autoregressive and moving average time series models that are established based on the F-criterion. A small reliability test system designated as the RBTS is used to illustrate the proposed method.

An improved reliability model for redundant protective systems-Markov models

A number of reliability models of power system components including protective-system failures have been proposed. These models have concentrated on modeling a single protective device. When this protections fails, it is usually assumed that backup protection will isolate the faulted component with 100% reliability. In reality, power system components, have redundant protection schemes with two or more protective devices operating in parallel. Existing reliability models have not dealt with redundant protective systems adequately. This paper presents an improved reliability model capable of modeling these systems. The proposed Markov model and the equations for a number of important performance indices are derived and illustrated in this paper using the data for a typical transmission system.

Distributed nature of residential customer outage costs

Reliability worth assessment is an important factor in power system planning and operation. An equally important issue is how to use customer costs of electric supply interruptions as surrogates to appropriately quantify reliability worth. Postal or in-person surveys of electric customers are often used to determine interruption costs. The results obtained from the surveys are transformed into customer damage functions which are applicable to individual customer classes and sectors. Standard customer damage functions use aggregate or average customer costs for selected outage durations. This paper develops a practical alternative to the customer damage function method of describing the interruption cost data. The alternate technique, which is designated as the probability distribution approach, is capable of recognizing the dispersed nature of the data. The proposed probability distribution method is illustrated in this paper using the interruption cost data collected in a 1991 survey of the Canadian residential sector.

Cost/benefit analysis of an AMR system to reduce electricity theft and maximize revenues for Électricité du Liban

One of the largest pitfalls for any distribution network is the level of energy losses suffered by the system. These losses fall into two categories: technical and non-technical. Technical losses depend largely on the physical properties of the network, while non-technical losses (sometimes a more significant form of losses) are the result of theft or fraud caused by meter tampering, false reading, illegal connections or unpaid bills. In Lebanon, the levels of total losses are around 50% resulting in an annual deficit of more than 225 million US dollars. Despite the frequent breakdowns of the system and evidently unsustainable financial-losses, political consideration makes the sustained pursuit of electricity thieves low on the list of priorities. To overcome these hurdles, the national electricity company in Lebanon, Electricite du Liban (EDL), studied the possibility of using automatic meter-reading (AMR) technology to modernize electricity metering, billing and collection, minimize fraud and maximize revenues. The results of this study and a cost/benefit analysis of the proposed system are summarized in this paper.

Assessment of energy efficiency options in the building sector of Lebanon

This paper examines the merits of implementing energy efficiency policies in the building sector in Lebanon following the approach normally adopted in Climate Change studies. The paper first examines the impact of the energy sector on the Lebanese economy, and then assesses the feasibility of implementing suitable energy efficiency options in the building sector. For this purpose, a detailed analysis of the building sector in Lebanon is presented with emphasis on the thermal characteristics of building envelopes and the energy consuming equipment. The long-term benefits of applying energy efficiency options in the building sector are then assessed using a scenario-type analysis that compares these benefits against those of a baseline scenario that assumes no significant implementation of energy efficiency policies. Finally, feasible options are highlighted and recommendations to remove the major barriers hindering the penetration of energy efficiency options in the Lebanese market are provided.

Design and cost analysis of an automatic meter reading system for Electricite du Liban

Abstract This paper summarizes the results of a study for modernizing the electricity metering, billing and collection processes for Electricite du Liban (EDL), the national power company of Lebanon. The objective of this study is to provide EDL with the best alternatives for modernizing their electricity metering of low-voltage customers. These customers are currently being metered using a variety of old and new electromechanical meters. The metering process at EDL is manual, and prone to errors. The existing system does not provide EDL with reliable methods to readily check bills, identify problematic customers, and reduce fraud. Therefore, EDL’s modernization requirements include an automated system capable of enhancing current metering processes, minimizing fraud, and maximizing revenue collection. This paper will describe the functional requirements of EDL and investigate the feasibility of using Automatic Meter Reading (AMR) technology to satisfy these requirements. Both procedural and equipment modernization techniques will be identified and assessed. The proposed modernization system will make EDL’s metering activities as advanced as those of modern utilities. Most importantly, with the modernized system, EDL will regain the confidence of its customers, and would become a highly reputable and revenue generating organization.

Evaluation of the energy policy for Lebanon

The Lebanese Electric Power System (LEPS) suffers from technical and financial deficiencies that required the development of a policy paper to rescue it from its drastic situation to a new sustainable, reliable, and efficient delivery of electricity. An energy policy that includes ten strategic initiatives and 42 action steps that are integrated and correlated to cover the sectors infrastructure, supply/demand, and the legal aspects was proposed and approved by the Government of Lebanon. This paper describes the current technical and financial situation of the LEPS and the need for an energy policy. The stochastic Load Modification Technique (LMT) is then used to assess the impact of implementing the projects proposed in the energy policy on energy production, overall cost, technical and commercial losses, reliability and customer service. The proposed technique is used to establish a technical and financial baseline of the LEPS against which the full implementation of the energy policy is compared and the resulting tariff is calculated.

An Experimental Study of a Collector and Diffuser System on a Small Demonstration Wind Turbine

A diffuser-augmented wind turbine (DAWT) has been an attractive concept of wind energy extraction since the early 1970s, due to the systems ability to increase the power generated by a regular bare turbine of the same size. However, the DAWT needs to reach a minimum augmentation ratio of 4 in order to become economically feasible. This paper investigates the possible improvement of a DAWT system by adding a collector fuselage to increase its augmentation ratio. Testing using a small experimental unit shows that adding a collector increases the power augmentation of the DAWT by more than 50%, and increases the mass flow rate through the turbine by increasing the effective upstream area of the wind that enters it. Changing the angle of the incident wind on a collector- and diffuser-augmented wind turbine (CDAWT) shows that it is possible to capture the energy in the wind up to an angle of 71°. Moreover, the CDAWT can keep extracting wind energy, without any diminution of the augmentation ratio, as wind direction varies ±45° from the turbine axes, thus eliminating the requirement for a yaw mechanism. Hence, the variant wind direction has a positive effect on the augmentation ratio.

Evaluation of the marginal outage costs in generating systems using quantitative power system reliability techniques

Marginal outage costs are an important component of electricity spot prices. This paper describes a methodology based on quantitative power system reliability techniques for calculating these costs in generating systems. The proposed method involves the calculation of the incremental expected unserved energy at a given operating reserve and lead time and the multiplication of this value by the average cost of unserved energy of the generating system. The method is illustrated in this paper by calculating the marginal outage cost profile of a small reliability test system. The effects of selected modelling assumptions and the accuracy of a number of approximate methods for calculating the marginal outage cost are also examined. 1998 John Wiley & Sons, Ltd.