Aleksandar Janjic

Multi-criteria decision support for optimal distributed generation dispatch

The problem of optimal dispatch of distributed generation (DG) differs from the classical problem of generation dispatch in the power system, because of the specific criteria related to the DG interconnection. Most important goals are to maximize the renewable production and to minimize the total cost, while satisfying additional constraints related to the operation of a distribution network. When there are many DGs in a distribution network, it is very complicated to decide the optimal DG outputs to satisfy all the criteria and constraints imposed by the distribution network. Another problem is the lack of the dispatcher control over DGs, and very often, the only available action is to switch on or off the generator. Finally, network operator and DG owner perspective is often opposed regarding appropriate control action in the network. In this paper, a multi-criteria decision support based on AHP method is proposed for the choice of the dispatching action. The method is illustrated on the choice of the DG to be switched off in the case or reverse power flow.

Multi-criteria Influence Diagrams – A Tool for the Sequential Group Risk Assessment

This chapter describes the use of influence diagrams in the risk assessment and proposes their extension to the group decision making using fuzzy logic, sequential approach and multi-criteria evaluation. Instead of classical Bayesian networks using conditional probability tables that are often difficult or impossible to obtain, a verbal expression of probabilistic uncertainty, represented by fuzzy sets is used in this approach. Influence diagrams are modeling the multistage decision processes and the interrelations among different chance and value nodes as well, enabling the iterative approach to the risk assessment. After the first, independent assessment of the group of experts, this preliminary risk grade is the input in the second step where the adapted risk grade has been adopted based on known evaluations, and interaction among decision makers. The different risk components and decision maker’s attitudes are considered by ordered weighted averages (OWA) operators. This inference engine is illustrated through the assessment of risk caused by improper drug storage in pharmaceutical cold chain by the group of experts in the iterative assessment process.

Optimal number of electric vehicles in electricity distribution company

In this paper, the optimal vehicle fleet mix composed of both electric and gasoline powered cars for the electricity distribution company has been determined. The optimization is performed based on multi-criteria analysis and OWA operators. The criteria for the proper choice of vehicles encompass the service quality, CO2 emission, the overall fleet costs and the possibility to use storage capabilities of electric vehicles. The methodology is illustrated on the vehicle fleet determination for the medium size distribution company with 50 000 consumers.

Optimal vehicle fleet mix planning in a distribution utility using fuzzy multi-criteria decision making

Electric power distribution utilities are using different types of vehicles, depending on their purpose, terrain properties, adopted typical scheme of utility organization and of current fluctuation on a vehicle market as well. Vehicle fleet planning is a generic and broad class of practical decision making problems, including the optimal fleet mix problem. Fleet mix planning involves the determination of a combination of vehicles that is expected to maximally fulfil the fleets mission objectives subject to constraints on the acquisition, deployment and operation of the fleet. However, to determine the optimal mix is a difficult task having in mind several criteria that one must meet simultaneously. For that reason, in this paper a multi-criteria fuzzy decision making technique is proposed for the determination of an optimal number of two types of vehicles. Optimization is carried out for several part of one distribution utility, with very different properties, and compared with two other multi-criteria decision methods. Thanks to its flexible approach, the fair and balanced distribution of vehicles among utilitys parts is made possible.

Distribution Network Risk Assessment Using Multicriteria Fuzzy Influence Diagram

Risk assessment of distribution assets is one of the most important factors in the process of network development or maintenance planning decision-making. The process of decision-making is faced with uncertainties, involving technical, financial, safety, environmental, and other operational issues that make standard risk assessment techniques insufficient. Probabilistic uncertainties require appropriate mathematical modeling and quantification when predicting future state of the nature or the value of certain parameters. The paper is proposing a new methodology for the multicriteria risk assessment of the distribution network assets, based on influence diagrams and fuzzy probabilities. Influence diagram has been used to determine all relevant factors concerning risks and their interdependencies are depicted. Fuzzy probabilities are represented by triangular fuzzy numbers with constraints on feasibility of elicited probabilities. This methodology enables the decision process in uncertain environment, with the impact evaluation of each particular distribution asset, or the asset component. The methodology is illustrated on the example of a distribution substation circuit breaker maintenance strategy selection.