Search

An interruptible load management (ILM) scheme is proposed using dynamic Optimal Power Flow analysis. It enables real-time selection of interruptible loads incorporating network constraints and dynamic restriction on generation viz. ramp-rate limits. The model provides an analytical framework for addressing several important issues associated with optimal selection of load curtailment e.g. advance notification for load curtailment, short-term price discounts and long-term discounts on demand-charges, power factor of the load and customer-cost associated with the load to be curtailed, and system security. A six-bus example illustrates the proposed methodology. Keywords: Interruptible Load management, Optimal Power Flow, Discount on Spot-Price, Discount on Demand-Charge

The paper discusses the major planning issues pertaining to economic operation of power system in India viz. integrated operation of the State Electricity Boards (SEBs) through formation of National Grid, optimal sharing of central sector generation by the SEBs, time-of-day pricing policy for power trading among the SEBs, optimal expansion of National Grid and streamlining the coal production and transportation for optimal system operation. A multi-area linear programming (LP) model NATGRID is developed to quantify the benefits from National Grid operation, suggest optimal sharing norms for central sector generation and formulate time-of-day pricing scheme for interutility power trading. Four interregional transmission projects are identified by exploiting the duals of the LP problem, for expansion of National Grid. The bottlenecks in coal production and transportation systems are indicated and the system cost savings from removing them are quantified. The analysis aims at encouraging and motivating the utilities to accept the idea of co-operation and making investment more cost-effective.

The paper presents an integrated framework to analyze the issues of reactive power planning alongwith reactive power pricing. The planning problem involves optimal placement and sizing of capacitors in a network such that operating and investment costs are minimum. A simple bus-wise cost-benefit analysis (CBA) scheme is proposed which Involves solving a modified optimal power flow problem (OPF) iteratively. The proposed CBA incorporates detailed hourly loading conditions at a bus and achieves a fairly accurate estimate of the benefits from capacitor placement. The formulation is directly handled by the well known MINOS code and is solved efficiently. It obviates the need to introduce Integer variables and is thus suitable for large system applications. A two-part reactive power spot-pricing scheme is formulated, by which the investment and operational costs can be recovered by the utility. The proposed reactive power price has two parts - a fixed part to account for the investment costs of new capacitor at a bus and a variable spot price to account for the operating costs incurred In supplying the additional reactive power from generating units.

The paper presents an integrated approach to least-cost generating unit maintenance scheduling for interconnected power systems. A Mixed Integer Programming (MIP) Model is developed which analyses the fuel supply decisions, generation and maintenance scheduling decisions as well as inter-utility transfer schedules in a comprehensive way. The method is applied to two interconnected Indian utilties. Firstly, the impact of fuel supply constraints and hydro energy availability on maintenance schedule has been examined for one utility. The analysis has further been extended to develop a centralized maintenance plan for both the utilities incorporating inter-utility transfer decisions. Studies reveal that interconnected mode of operation can lead to substantial changes in fuel supply decisions and the overall system operating costs are significantly reduced.

This paper proposes simultaneous integration of DSM options in a multiobjective framework (using compromise programming technique) for electric utility planning. The two distinct advantages of this method are: (i) explicit consideration of all associated benefits of DSM options viz. cost reduction, emissions reduction and improvement of supply system reliability (ii) consideration of the integration method specific characteristics of various types of DSM options depending upon the control of utility on their usage. The methodology is applied for an Indian utility (Maharashtra State Electricity System (MSES)) for its integrated resource planning for the period 1990-2000 to illustrate the methodological issues. Various methodological issues related to the specific nature of DSM options and multiobjective framework are discussed in the context of MSES. Keywords: Demand Side Management, Operational Planning, Compromise Programming