C.T. Tse

Algorithm for power system dynamic stability studies taking account of the variation of load power

This paper presents a probabilistic algorithm for determining the effect of initial state variation on the dynamic stability of power systems. Variation of operating conditions due to the uncertainties in load and generation is represented by the statistical attributes of nodal voltages. Expectation and covariance are employed to describe the distribution nature of random variables. The expected coefficient matrix in the state space equation is corrected by the second-order covariances. The solution gives the probabilistic distributions and conditional probabilities of eigenvalues. The proposed algorithm is examined on a two test systems.

Capacity-use and reliability based transmission embedded cost allocation with temporal considerations

Abstract Transmission services have to be provided as a separate item in a de-regulated or vertically restructured electricity supply industry. Though the primary function of a transmission line is to transmit power from source point(s) to loading point(s), major lines also play an important role in security. Sometimes a particular transaction cannot take place if a particular line is unavailable and, moreover, a specific line may be more important for the security of a particular transaction than it is for others. Clearly reliability is a relevant consideration in equitable cost allocation. A method for transmission line embedded cost allocation among transmission transactions accounting for both line capacity-use and reliability benefit is presented. Line capacity-use is determined by the amount of power transmitted, while the reliability benefit is calculated as the increment of the total probability of system failure, with the line out of service, compared to when the line is in service. Capacity-use is determined using a full AC power flow and hence the effects of reactive power can also be investigated. The cost allocation to each transaction according to the capacity-use and reliability benefit patterns throughout an accounting period during which system loading and line failure probability are varying are studied.

Robust PSS design by probabilistic eigenvalue sensitivity analysis

Abstract When a wide range of system operation is taken into account for power system dynamic studies, probabilistic eigenvalue analysis efficiently provides the statistical distributions of concerned eigenvalues. Under the assumption of normal distribution, each eigenvalue can be described by its expectation and variance. To enhance system damping under multi-operating conditions by power system stabilizers (PSSs), effects of PSSs on both eigenvalue expectation and variance should be investigated. In this paper, the conventional eigenvalue sensitivity analysis has been extended to probabilistic environment. Eigenvalue sensitivities for both expectation and variance are determined to form two types of probabilistic sensitivity indices (PSIs). Robust PSS locations are selected by one type of PSI, PSS parameters are tuned by the probabilistic sensitivity analysis using another type of PSI.

Selection of the location and damping signal for static var compensator based on a versatile modeling

Abstract A highly versatile method suitable for modeling different flexible AC transmission systems (FACTS) components is introduced. State space model of the entire multimachine system can be automatically established irrespective of the system complexity and the choice of control signals. Exploitation of eigenvector analysis to the static var compensator (SVC) study is illustrated by using modal and sensitivity techniques to select the effective location and damping signal. A similar approach can be extended to other FACTS devices based on the proposed modeling methodology.

A new H∞ based PSS design using numerator–denominator perturbation representation

Abstract A new H∞ PSS design method which uses the numerator–denominator perturbation representation and includes the partial pole placement technique and a new weighting function selection method is proposed. This overcomes certain conventional H∞ PSS design algorithm limitations. A robust PSS has been successfully designed by treating the highly non-linear characteristic of the power system as model ‘uncertainty’. The design is verified to have better performance for a wide range of system operating conditions when compared with the conventional PSS design.

Energy transaction scheduling with interchange capability assessment under open transmission access

Abstract Power system operation with multiple energy transactions poses one of the challenges to the new competitive open-access power market environment. In this paper both individual and group transactions are assumed to exist in a power market. Transmission dispatch methodology for transaction requests to ensure feasibility and assessment of transfer capability of the transmission network to accommodate additional power transfers for selected transactions are developed. A transmission dispatch methodology is proposed to curtail requested transactions to ensure that there is no operating constraint violation. The transfer capability problem is thus formulated as an optimum power flow (OPF) problem where the objective is to assess the transfer capability for a set of selected transactions. The methodology is applied to a sample power network to verify its validity.