Showing papers by "Chen-Ching Liu published in 2000"

Optimal electricity supply bidding by Markov decision process

Abstract: The bidding decision making problem is studied from a supplier's viewpoint in a spot market environment. The decision-making problem is formulated as a Markov decision process-a discrete stochastic optimization method. All other suppliers are modeled by their bidding parameters with corresponding probabilities. A systematic method is developed to calculate transition probabilities and rewards. A simplified market clearing system is also included in the implementation. A risk-neutral decision-maker is assumed, the optimal strategy is calculated to maximize the expected reward over a planning horizon. Simulation cases are used to illustrate the proposed method.

The strategic power infrastructure defense (SPID) system. A conceptual design

Abstract: A power system can become vulnerable for various reasons, these sources of vulnerability are either internal or external to the infrastructure that comprises the power system. Threats from vulnerability sources that are internal to the civil infrastructure may be reduced by decreasing the probability and severity of occurrence through the improved engineering of related systems. On the other hand, threats from vulnerability sources that are external to the infrastructure may be reduced by decreasing the severity of occurrence. To prevent or reduce catastrophic failures and cascading sequences of events caused by the various sources of vulnerability, the Advanced Power Technologies Consortium is researching ways to revolutionize defense strategies and technologies that will significantly reduce the vulnerability of the power infrastructure. Our vision is a wide-area, intelligent, adaptive protection and control system that empowers future grids by providing critical and extensive information in real time, assessing system vulnerability quickly, and performing timely self-healing and adaptive reconfiguration actions based on system-wide analysis. The proposed system is referred to as the strategic power infrastructure defense (SPID) system. The article discusses the conceptual design of the SPID system and the associated technical challenges. The fundamentally important concept is that the SPID system provides self-healing and adaptive reconfiguration capabilities for power grids based on wide-area system vulnerability assessment. Some experts believe that if 0.4% of the load had been shed for 30 minutes, the widespread power outage in the Western United States on 10 August 1996 could have been avoided. The SPID is intended to identify such load-shedding actions in real time based on proposed vulnerability assessment and protection/control systems.

Pricing flexible electricity contracts

Abstract: This paper is concerned with pricing of electricity contracts that allow flexible scheduling of the supply or demand of electric energy. The contracts are priced based on the principle of no-arbitrage. Variables of the contracts are used to determine arbitrage opportunities and the price of contracts. Pricing of flexible contracts involves a scheduling policy. By representing the spot price with an appropriate stochastic process, the scheduling policy can be found using stochastic dynamic programming. Simulation examples illustrate the tradeoffs between prices and scheduling flexibility.

Analysis of electricity market rules and their effects on strategic behavior in a noncongestive grid

Abstract: Earlier work has discussed the potential for strategic bidding in deregulated electricity markets, and shown specially how generators can take advantage of congestion in their strategy. The authors show that it is also possible for even mid-price suppliers to create congestion problems through gaming in a noncongestive system. Under auction mechanisms such as in the United Kingdom, this can be profitable, at the consumer's expense. The optimal auction prevents profitable gaming, but requires the simultaneous handling of market clearing and system dispatch, making it harder to ensure the neutrality of system operations.

New methods for electric energy contract decision making

Abstract: This paper is a summary of our research on contract decision making in a competitive electricity market. Bidding decision in a spot market is formulated as a Markov decision process that can be used to determine the price and amount of electricity for a supplier. Pricing in a bilateral market is calculated using the no-arbitrage principle and stochastic optimization. We also propose a method to minimize the uncertainty of profit.

Complete controllability of power system dynamics

Abstract: This paper summarizes our results of a study on the complete controllability of power systems. With a nonlinear dynamic power system model, it is shown that power systems are completely controllable within a region of the state space. In other words, with the available controls, a power system can be steered from one state to any other state within the complete controllability region. The study also provides a strategy for constructing the complete controllability region. The results imply that during emergencies, if the power system states are in the complete controllability region, the movement of the power system states can be directed toward a desired operating point so that events like a voltage collapse can be avoided.