X. Yin

Probabilistic analysis of power system small signal stability region

With the deregulation of power industry in many countries, the traditionally vertically integrated power systems have been experiencing dramatic changes leading to competitive electricity markets. Power system planning in such an environment are now facing increasing requirements and challenges because of the deregulation. The traditional deterministic power system analyses techniques have been found in many cases have limited capability to reveal the increasing uncertainties in todays power systems. The power system operation and planning are demonstrating probabilistic characteristics which requires emphasizes on probabilistic techniques. A key probabilistic power system analysis technique is the probabilistic power system small signal stability assessment technique. With the many factors such as demand uncertainty, market price elasticity and unexpected system congestions, it is more appropriate to have probabilistic power system stability assessment results rather than a deterministic one especially for the sake of risk management in a competitive electricity market. We present a framework of probabilistic power system small signal stability assessment technique in this paper supported with detailed probabilistic analysis and case studies. The results of this paper can be used as a valuable reference for utility power system small signal stability assessment probabilistically and reliably.

Optimal portfolio selection for generators in the electricity market

With the deregulation of global electricity industries, generators are facing a problem of designing the optimal portfolio, which is made up of a variety of markets and contracts, in a competitive electricity market. Theoretically, the portfolio selection problem can be solved by allocating generation capacities to proper markets and financial contracts, so as to obtain the optimal trade-off between the portfolio return and risk. In this paper, we propose a novel approach which can well solve the generator portfolio selection problem. Considering different planning horizons in practice, the problem can be converted into two sub-problems, which are long term portfolio selection and short term portfolio selection. The mathematical formulations of different asset returns for both the long term and short term portfolio selection have been derived. To model the highly volatile spot market price, a time varying volatility model is introduced. The portfolio selection problem is finally formulated as an optimization problem, which can be solved by the Differential Evolution algorithm. The proposed method is tested with real market data. Cased studies further validate its effectiveness by real market data and demonstrate its promising performance achieved.

Managements of Generalized Congestions

It is well known that power system operations are often constrained by transmission congestions which reflect the physical restrictions intrinsic to the power system itself. The power market running on top of the system is also constrained by factors such as primary energy, emissions, technical support, as well as multi-player gaming among market participants including regulators. In this paper, we propose a new concept of generalized congestions to describe those factors affecting both the competition level and the efficiency of power markets. Market power is a market participants capability in influencing market efficiency with the aid of generalized congestions; generalized market power reflects its capability to influence the social welfare. This paper analyzes generalized congestions, market power and generalized market power in many aspects including taxonomy, evaluation indexes, control measures. and the corresponding research methods. Based on the experimental economics method, a research framework is proposed to facilitate comprehensive studies on the influences of generalized congestions on market power.

A coordinative method for interruptible loads management in an electricity market

There are two compensation methods for interruptible loads (ILs), namely low price compensation before supply unavailability and high price compensation after supply unavailability. Low price compensation is independent of power supply unavailability, while the high compensation is performed only after actual power supply unavailability. However, the IL with low price (ILL) and the IL with high price compensation (ILH) have only been studied separately till now. Based on risk management, this paper analyzes the different economic properties of the two compensation methods and concludes that their coordination is beneficial to restrain market power and reduce the cost of reserve capacity. The authors propose the coordination models and optimization algorithms by taking the sum of the deterministic reduction of revenue resulting from ILL and the risk of compensating ILH as the objective function. Simulation results are presented to validate the effectiveness of the proposed method.