00826623 A Network-flow Approach For Security Constrained Economic Dispatch

A Network-Flow Approach for Security Constrained Economic Dispatch of Power Systems

Ching-TzongSu

Ying-Chang Hsiao

Yuh-Chyuan Su

Institute of Electrical Engineering National Chung Cheng University, Chiayi 621, Taiwan Fax: XX6-52720862 Email: [email protected] Abstract - An approach based on transportation technique for economic dispatching of a generation-transmission composite system is presented. Component outages are considered. Through application of the Monte Carlo simulation and the Minimum-Cost Maximum-Flow algorithm, this approach searches the cheapest (minimum cost) path of a graph and then determines the maximum flow (minimum capacity of the branches of the cheapest path) for power dispatching. Through repetitive application of the algorithm, a near optimal power flow pattern can be determined and thus security constrained economic dispatch is obtained.

m 4 1 From a Base Graph

Perform the Next Statistical Simulation

Apply Monte Carlo Simulationto Simulate the State of the

Keywords: Economic Dispatch, Monte Carlo simulation, Minimum-Cost Maximum-Flow, Graph.

Flow algorithm to evaluate the economic dispatch solution

I. INTRODUCTION

Conventionally, economic dispatch methods of composite systems are based on the use of B-coefficients or the Jacobian inverse matrix to determine penalty factors . Traditionally, the economic dispatch problem is solved by mathematical programming methods and optimization techniques. An alternative method applying transportation technique is presented for calculking production cost of generation and transmission systems, but the method does not consider apparatus forced outages. In the approach presented, we consider system reliability, and we apply the Monte Carlo simulation and graph techque. The original network is first represented as a base graph. Subsequently, we employ the Monte Carlo simulation to obtain a corresponding reduced graph. Then the Minimum-Cost Maximum-Flow algorithm is applied to evaluate a pertinent power dispatch. Repetitive application of the simulations, we finally obtain an expected economic dispatch solution. 11. FLOW CHART OF THEPROPOSED METHOD

Schema of the main steps involved in the methodology presented is shown in Fig. 1.

Statistical

Yes

Calcult the Expected Values and Print the

Fig. 1. Flow chart of the computationalprocedures for the proposed method LU. CONCLUSIONS A new method based on the network-flow techmque and Monte Carlo simulation has been developed to determine production cost for generation and transmission composite systems. The accuracy of the solution and the computing requirements increase as the power quantizations size decreases and the simulation number increases.

In addition to unit generations, the proposed method provides, as byproducts, a great deal of useful information. This includes system production 'cost, line flows, load demand served, and system reliability.

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