IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 27, NO. 4, NOVEMBER 2012 2295

Foreword:Special Section on Adequacy in

Power Systems With Intermittent Sources

P OWER system adequacy relates to the existence of suffi-cient facilities within the system to satisfy consumer load

demands and system operational constraints under a variety ofuncertainties in all normal and contingency states. For decades,system adequacy issues have been extensively investigatedfrom a viewpoint of probabilistic reliability. However, newchallenges appear as intermittent sources are integrated intosystems. These are associated with not only adequacy evalua-tion in generation, transmission, distribution, and micro-gridswith randomly intermittent sources but also coordination in ad-equacy between different intermittent sources such as wind andsolar energies, between intermittent sources and random loads,and between intermittent sources and storages. Integration ofintermittent sources in power systems requires development ofnew ideas, models, methods, and computing tools for systemadequacy assessment.This special section, which includes 11 papers, addresses this

need. The papers discuss from different perspectives various as-pects of adequacy in power systems with intermittent sources.They provide an overview of current research activities on thetopics. It is our belief that the concepts, methodologies, and pro-cedures presented in the papers are valuable contributions andwill serve as good references for future research on the subjectmatter.The idea of the special section came from a suggestion of

Editor-in-Chief Antonio Conejo. We went through two stages.In the first one, 63 summaries were received and 20 authors wereinvited to submit full papers. In the second one, all of the 20submissions were subject to a regular review process. Based onreviewers’ comments, 11 papers were eventually selected. Othersummaries and papers did present some good ideas but werenot selected for different reasons. In the 11 papers eventuallyselected, 9 focus on adequacy evaluation in a planning sense and2 on operation adequacy. The papers cover the issues which canbe outlined as follows:Roy Billinton et al. present some of the basic factors and

procedures that need to be considered when conducting windintegrated system adequacy assessment. Focus is placed onwind speed data representations, wind energy conversionsystem models, simulation analysis techniques and applicationsin generation and bulk system adequacy evaluation.WijarnWangdee’s paper extends the concepts of the effective

load carrying capability (ELCC) and the generation replacementcapability (GRC) to consider both generation system adequacyand security. A system well-being analysis is utilized to capturethe characteristics in the two reliability standpoints.

Digital Object Identifier 10.1109/TPWRS.2012.2214172

Armando Leite da Silva et al. propose a chronological powerflow (CPF) based method to identify transmission branches thatrestrict wind power flows in power systems integrated with highpenetration of wind energy. The proposed methodology can beused as an analysis tool for transmission system planning con-sidering intermittent sources.Leonel de Magalhaes Carvalho et al. provide a Monte Carlo

simulation based technique for detecting and assessing windpower curtailments due to inertial and transmission constraintsin power systems with high penetration of wind energy sources.The presented technique can help analyze how to maximize in-tegration of wind generation to grid system.The paper by Yixing Xu and Chanan Singh tackles adequacy

and economic analysis of distribution systems integrated withboth wind farms and energy storages. A reliability and economicassessment framework is presented using a sequential MonteCarlomethod combinedwith amodel-predictive-control (MPC)based operation strategy.The paper by Zhaohong Bie et al. deals with reliability eval-

uation of distribution systems containing multiple micro-gridswith intermittent sources. A concept of virtual power plant ispresented to model micro-grids and the two-step state sampling,zone partitioning, and minimal path search are integrated to im-prove the state evaluation process.Maryam Dadkhah and Bala Venkatesh propose a cumulant

based method of determining optimal sizes and locations of ca-pacitor banks in distribution systems with wind farms. The re-sults are compared with those obtained using a traditionalMonteCarlo technique.Joydeep Mitra’s paper describes a method of determining

storage capacities required to meet reliability targets for island-capable micro-grids with intermittent sources. The method hasbeen successfully applied to both military and civilian cases.Amir Safdarian et al. devise an explicit mathematical frame-

work for coordination between wind and solar energy sourcesin hybrid photovoltaic-wind systems to maximize system relia-bility subject to a fixed investment cost. Uncertainties associatedwith hourly loads, wind speeds, solar radiation, and componentfailures are modeled.Peng Wang et al. discuss a technique to evaluate operation

adequacy and energy utilization efficiency of power systemswith high penetration of wind power. Ramp rates of conven-tional generators and energy storages are modeled.Guodong Liu and Kevin Tomsovic present a probabilistic

method to quantify the optimal amount of spinning reserve inpower systems with significant wind power penetration. Uncer-tainties of load and wind speed forecasts are formulated in a unitcommitment model.

0885-8950/$31.00 © 2012 IEEE

2296 IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 27, NO. 4, NOVEMBER 2012

It should be noted that although the papers cover a wide range,it is impossible for only 11 papers to touch all issues on the sub-ject. For example, impacts of large-scale penetration of elec-tric vehicles and capacity market on adequacy in power systemswith intermittent sources, which are the two topics included inour original Call-for-Papers, have not been addressed in the pa-pers. We expect that this special section will play a role in pro-moting further enthusiasm for research work in this area.We appreciate the innovative and original work of the authors

and their careful responses to our many requests for revisionsand clarifications. Our thankfulness is extended to all reviewersfor their thoughtful comments that helped improve the qualityof the papers. We are grateful to Dr. Antonio Conejo for his

suggestions, support, and guidance during the whole processwhen we were managing the special section.

WENYUAN LI, EditorBC HydroVancouver, BC, CanadaWenyuan.li@ieee.org

LALIT GOEL, Guest EditorNanyang Technological UniversitySingaporeELKGOEL@ntu.edu.sg