Adirak Kanchanaharuthai

Transient Stability and Voltage Regulation in Multimachine Power Systems Vis-à-Vis STATCOM and Battery Energy Storage

This paper examines the application of STATCOM and battery energy storage to enhance the transient stability of large-scale multimachine power systems with synchronous and doubly-fed induction generators (DFIGs). A passivity-based control design method [interconnection and damping assignment passivity-based control (IDA-PBC)] is developed for multimachine power systems and its performance is evaluated on a two-area system consisting of two synchronous generators (SGs) and two DFIG along with STATCOM/battery energy storage system. The main contributions of this paper are threefold: 1) use of a STATCOM and battery energy storage system to enhance transient stability and provide voltage regulation with SG and DFIG; 2) demonstrating the application of nonlinear control theory (specifically the IDA-PBC methodology) for the design of a stabilizing feedback controller in large-scale power systems to improve transient system performance; and 3) developing a methodology that can use the additional degrees of freedom in large-scale power systems in order to further improve system performance, in particular the transient stability margin [measured through critical clearing time (CCT)] and the dynamic transient performance of the system. In order to achieve power angle stability along with the simultaneous regulation of frequency and voltage, the performance of the proposed control scheme after the occurrence of large disturbances is evaluated and compared with a conventional power system stabilizer and a feedback linearizing controller.

Optimal sampled-data controller design with time-multiplied performance index for load-frequency control

This work presents an optimal sampled-data controller design with time-multiplied performance index based on dynamic programming for the load frequency control problem of a power system. This sampled-data controller is used in order to achieve not only in improving faster transient response, such as the incremental frequency deviation, but also in extending the structure of the sampled-data controller from the standard optimal performance index to the case of time-multiplied one. It is assumed here that the complete state observations are sampled at sampling time t/sub k/ to use in constructing a desired controller. The simulation results are shown to illustrate the effect of a time-multiplied performance index on the faster transient response of the regulated output.

Immersion and Invariance-based Non-linear Coordinated Control for Generator Excitation and Static Synchronous Compensator of Power Systems

Abstract In this article, a non-linear coordinated control of generator excitation and a static synchronous compensator is proposed to enhance the transient stability of an electrical power system. The coordinated controller proposed is designed via immersion and invariance methodology. In particular, a non-linear model of the power system and immersion and invariance design method are used to achieve not only power angle stability but also frequency and voltage regulations following a large disturbance (a symmetrical three-phase short-circuit fault) on one transmission line or a small perturbation to mechanical power input to synchronous generators in the system. The controller design is validated using a simulation study on a single-machine infinite bus. Simulation results show that the proposed controller can not only keep the system transiently stable but also simultaneously achieve power angle stability and frequency and voltage regulation.

Immersion and Invariance-Based Coordinated Generator Excitation and SVC Control for Power Systems

A nonlinear coordinated control of excitation and SVC of an electrical power system is proposed for transient stability, and voltage regulation enhancement after the occurrence of a large disturbance and a small perturbation. Using the concept of Immersion and Invariance (I&I) design methodology, the proposed nonlinear controller is used to not only achieve power angle stability, frequency and voltage regulation but also ensure that the closed-loop system is transiently and asymptotically stable. In order to show the effectiveness of the proposed controller design, the simulation results illustrate that, in spite of the case where a large perturbation occurs on the transmission line or there is a small perturbation to mechanical power inputs, the proposed controller can not only keep the system transiently stable but also simultaneously accomplish better dynamic properties of the system as compared to operation with the existing controllers designed through a coordinated passivation technique controller and a feedback linearization scheme, respectively.

Nonlinear generator excitation and superconducting magnetic energy storage control for transient stability enhancement via immersion and invariance

This paper focuses on the design of nonlinear coordinated generator excitation and superconducting magnetic energy storage (SMES) control to enhance the transient stability of an electrical power system. An immersion and invariance (I&I) nonlinear control design technique is used to achieve power angle stability and frequency and voltage regulation, and to ensure that the closed-loop system is asymptotically stable. The main contributions of this paper are: (1) use of a generator excitation and SMES combination to improve transient stability, (2) demonstrating the applicability of nonlinear control theory (particularly the I&I methodology) for the design of a stabilizing (state) feedback controller in a single machine infinite bus system to enhance transient system performance and (3) developing a methodology that can employ the additional degree of freedom in power systems that include the combined excitation and SMES and advanced nonlinear control in a way that can further improve the dynamic transient performance of the system. In order to show the effectiveness of the proposed controller design, numerical simulation results are provided to illustrate the performance in maintaining stability and simultaneously achieving improvements in voltage regulation during small and large disturbances, and to show that our proposed nonlinear controller has more advantages by comparing it with the control performance of two existing nonlinear controllers and a conventional linear controller, in particular, feedback linearizing and coordinated passivation controllers, and a power system stabilizer (PSS), respectively.