Improve Power System Transient Stability Research Articles

Power System Transient Stability Improvement by the Interline Power Flow Controller(IPFC)

This paper presents a study on the power system transient stability improvement by means of interline power flow controller (IPFC). The power injection model of IPFC in transient analysis is proposed and can be easily incorporated into existing power systems. Based on the energy function analysis, the operation of IPFC should guarantee that the time derivative of the global energy of the system is not greater than zero in order to damp the electromechanical oscillations. Accordingly, control laws of IPFC are proposed for its application to the single-machine infinite-bus (SMIB) system and the multimachine systems, respectively. Numerical simulations on the corresponding model power systems are presented to demonstrate their effectiveness in improving power system transient stability.

Integrated Linear and Nonlinear Control of Unified Power Flow Controllers for Enhancing Power System Stability

This paper presents an integrated linear and nonlinear control for a unified power flow controller (UPFC). Three Pulse-Width Modulation (PWM) parameters of the UPFC are controlled by Proportional-Integral-Differential (PID) laws, and an analytic expression of the nonlinear control law for the UPFC phase angle ϕ2 is obtained by a feedback linearization method. This combined linear and nonlinear control strategy enables the UPFC to improvepower system transient stability and dynamic performance effectively. Simulation results illustrate the effectiveness of the developed control strategy.

Transient stability enhancement via coordinated excitation and UPFC control

This paper discusses coordinated excitation and UPFC control to improve power system transient stability. The power system is linearized through direct feedback linearization technique. Robust approach is employed to deal with the uncertainties caused by parameter variations and the inclusion of UPFC controller. Only local measurements are required for designing the excitation controller. The series branch of UPFC is designed to damp the power oscillation during transient period. The shunt branch aims at maintaining bus voltage. The performance of the controllers is tested on a single-machine infinite-bus (SMIB) power system. Simulation results show that both of the series and shunt branch of UPFC help improve transient stability.

Transient and voltage stability enhancement via co-ordinated excitation and UPFC control

The paper discusses co-ordinated excitation and UPFC control to improve power system transient stability and voltage stability. In the design of an excitation controller, the power system is linearised using a direct feedback technique. A robust approach is used to deal with the uncertainties caused by parameter variations and the inclusion of UPFC controller. Only local measurements are required for designing the excitation controller. The series branch of the UPFC is designed to damp the power oscillation during transients, while the shunt branch aims at maintaining the bus voltage. The performance of the proposed controller is tested on a single-machine, single-load power system. Simulation results show that the co-ordinated excitation and UPFC control is effective for transient stability enhancement. Both of the series and shunt branch control of UPFC help improve transient stability. The impact of the controller on voltage stability is studied through bifurcation analysis. It is shown that the feasibility region can be greatly increased.

Fuzzy control of thyristor-controlled series compensator in power system transients

Power system transient stability is one of the most challenging technical areas in electric power industry. Thyristor-controlled series compensation (TCSC) is expected to improve transient stability and damp power oscillations. TCSC control in power system transients is a nonlinear control problem. This paper presents a T–S-model-based fuzzy control scheme and a systematic design method for the TCSC fuzzy controller. The nonlinear power system containing TCSC is modelled as a fuzzy “blending” of a set of locally linearized models. A linear optimal control is designed for each local linear model. Different control requirements at different stages during power system transients can be considered in deriving the linear control rules. The resulting fuzzy controller is then a fuzzy “blending” of these linear controllers. Quadratic stability of the overall nonlinear controlled system can be checked and ensured using H ∞ control theory. Digital simulation with NETOMAC software has verified that the fuzzy control scheme can improve power system transient stability and damp power swings very quickly.

A comparison and simulation study of nonlinearly designed robust controllers for power system transient stability

In this paper, the robust mechanical and excitation control algorithms, together with power system stabilizer (PSS) are studied and compared. In light of the fact that theoretical results on Lyapunov stability have been established for these control algorithms, effort has been concentrated in this paper on comparisons between these algorithms and the conventional exciter and the PSS. It is shown through simulations on the 39-bus New England system that robust control algorithms are very effective in improving power system transient stability and that their combination shows a much better performance compared to that under any one of them. It is also through the simulation study that the problem of how to select control gains is addressed. In fact, it is shown that “optimal” gains exist and that they are not large.

Improvement of power-system transient stability by phase-shift insertion

Improvement of power-system transient stability by phase-shift insertion

Discussion on “Improvement of turbogenerator transient performance by control means” and “Improvement of power-system transient stability by phase-shift insertion”

Discussion on “Improvement of turbogenerator transient performance by control means” and “Improvement of power-system transient stability by phase-shift insertion”

Improving power system transient stability by pre-programmed optimum network switching

Improving power system transient stability by pre-programmed optimum network switching

Improvement of power-system transient stability by phase-shift insertion

Computational studies of the transient stability of a synchronous machine connected to an infinite busbar by a double-circuit transmission line are used to illustrate the effect of relative phase-shift insertion between the machine and its associated power system. This method of obtaining a change in the effective rotor-excitation angle, and thereby the power transfer, is described, together with an outline of possible methods of implementation by a phase-shifting transformer in a power system.