Reliability and Sensitivity Analysis of Composite Power Systems Under Emission Constraints

In view of the increasing role of environmental considerations in power generation, there is an evolving body of reliability methods that are cognizant of these emerging factors. This paper presents a method for analyzing the reliability of composite power systems under the constraints of CO₂, SO₂, and NO_x emissions. It also utilizes the concept of the shadow price to perform sensitivity analysis with respect to these constraints. The method presented here uses a linearized power flow representation in the form of a linear programming (LP) model similar to those frequently used in power system reliability studies. In addition to power balance and flow constraints normally used, this work introduces a suitably formulated set of emission constraints. The dual solution of the LP provides the shadow prices that are used for determining the sensitivities. This paper also develops relationships for the sensitivities of several reliability indices with respect to the emission allowances. The method is demonstrated on the IEEE-RTS and the results are presented.

I. Introduction

Following the introduction of the Clean Air Act Amendments of 1990, utilities have been required to reduce and monitor emissions from their power generating units starting from 1995. This act enforced allowances on emissions that could be used or traded within the specified banking period [1]. The most significant reductions have occurred very recently. On November 14, 2012, California had its first auction and trading on greenhouse emission allowances [2]. Starting January 2013, California's emission cap-and-trade program came into effect, and greenhouse gas emissions from large electric power plants are required to be reduced by 16% between 2013 and 2020 [2]. The Regional Greenhouse Gas Initiative (RGGI), which consists of nine North-Eastern and Mid-Atlantic states, agreed on reduction of budget by 45% by 2014 and the reduction will decrease by 2.5% yearly from 2015 to 2020 [3]. The American Clean Energy and Security Act of 2009 provides for the reduction of carbon emissions by 17% by 2020. The European Union Emissions Trading System reduced greenhouse gas emissions more than 8% between 2008 and 2012 and is expected to reduce greenhouse gas emissions below 20% of the 1990 levels by 2020, starting from 2013 [4].