This paper describes an adaptive tuning of parameters of a power oscillation damping (POD) controller for FACTS devices. The FACTS devices considered here are the thyristor controlled series compensator (TCSC) and the unified power flow controller (UPFC). A residue method is applied to the linearized power system model to determine the best siting for FACTS devices as well as for the selection of measured signals. Information available from a higher control level, e.g. from a wide-area monitoring and control platform, is used for a fine tuning of the POD controller in case of changing operating conditions.

Application of FACTS devices for damping of power system oscillations

Analytic investigations of interarea oscillation damping of an idealized two-machine system using active-power modulation of three- and four-terminal high-voltage dc (HVDC) transmissions are presented. It is shown that, generally, the pairing of two terminals gives the highest damping. Based on the analytical results, recommendations for how the pairing should be made are developed. Simulations, both on a two-machine system and on a more realistic 23-machine system, verify the analytical results.

Interarea Oscillation Damping Using Active-Power Modulation of Multiterminal HVDC Transmissions

This paper describes a design of power oscillation damping (POD) as an add-on feature for power flow control The developed controller has been applied to two FACTS devices: Thyristor Control Series Capacitor (TCSC) and Unified Power Flow Controller (UPFC) The supplementary POD control design is based on the residue method Nonlineaz simulations show that the proposed method can significantly improve the dynamic performance of the power system

Damping Controller Design for Power System Oscillations

This paper presents an add-on self-tuning (ST) control scheme for a Unified Power Flow Controller (UPFC) to assist its conventional PI control system in damping power oscillations. The ST control algorithm is based on a Pole Shift (PS) technique that has previously been successfully applied in Adaptive Power System Stabilizers (APSSs). For a wide range of operating conditions, the conventional PI-UPFC unless returned suffers from insufficient/nonoptimal damping performance. To overcome this problem, the authors propose supplementing the PI controllers with an ST feedback loop comprised of an identifier and a PS control algorithm. With a CRLS identifier tracking the system conditions online, this scheme eliminates the need for PI parameter retuning. Further, to correctly identify system parameters during large disturbances, a constrained recursive least squares (CRLS) identification procedure is adopted here. An improved damping performance with the proposed add-on scheme assisting the nonoptimal PI-UPFC is demonstrated for a two-area power system.

An Add-On Self-Tuning Control System for a UPFC Application

Because of the power industry moving toward marketoriented, the power tends to be transmitted over longer distances. However, the capability of long, inter-regional power transmission is usually limited, and one of the limitations is caused by low-frequency power oscillations. One of the critical oscillation, known as Inter-area oscillation, is observed when a group of generates in one region swings against group in another region [1]. The traditional solution is to use power system stabilizers (PSSs) on generator excitation control systems [2]. However, PSSs are usually designed for local oscillation damping, and in large multi-area power systems it might be difficult to tune all the PSSs parameters. FACTS devices can be employed for inter-area power oscillation damping (POD), and they are proved to be effective [3], [4], [5].

Utilizing Distributed Power Flow Controller (DPFC) for power oscillation damping

This paper describes an adaptive parameter tuning of a power oscillations damping (POD) controller for the thyristor controlled series compensator (TCSC). The adaptive control is based on pole shifting. In order to maintain good damping over a wide range of operating conditions, the parameters of the POD controller are adapted on-line, based on the measured system input and output. Simulation results are provided to demonstrate the effectiveness of the proposed controller.

Self-tuning controller for damping of power system oscillations with FACTS devices

This work is a step towards real-time implementation of a single-input single-output (SISO) adaptive controller scheme for power oscillations damping (POD) making use of fast power electronic devices such as FACTS (flexible AC transmission systems). The adaptive control is based on a recursive parameter estimation using Kalman filtering techniques and a pole shifting method which takes into consideration also the physical limits of the control signal. The method has been evaluated in non-linear simulations. It will be followed by real-time tests on a dedicated hardware platform.

Towards Real-time Implementation of Adaptive Damping Controllers for FACTS Devices

This paper discusses power flow control in electric power system by use of unified power flow controller (UPFC) A current injection model of the UPFC is used The contro1 objective is to maintain the line power flow of a controlled line at a desired value The control objective can be achieved by lincarizing the line power flow equations around the operating point The paper introduces the criterion for validation of two proposed control methods The UPFC and power system network model have been developed in Matlab/Simulink environment for the simulations to demonstrate the proposed methods

A power flow control strategy for facts devices

SUMMARY By controlling the power flows in the network, FACTS devices can help to reduce the flows in heavily loaded lines, resulting in lower system losses, improved stability of the network or reduced costs of the production. It is important to investigate the location for placement of these devices because of their considerable cost. Locations of FACTS devices in the power system can be obtained on the basis of static and/or dynamic performance. The intended objective of the FACTS device will have a large impact on the optimal location of the devices. A location that is the best for one objective may be less suitable for another. The location of a Thyristor Controlled Series Capacitor (TCSC) can be evaluated based on a sensitivity analysis in order to control power flow in the system, or based on a residue approach in order to influence the damping behaviour of the system. Sensitivity analysis determines the influence on each variable due to the changes in the system. It is a direct measure of the controllability of the active power flow in specified line by the TCSC located in the same, or in another line. On the other hand, the residue method gives very effective approach to determine the location of TCSC, due to the fact that a larger residue results in a larger change of the corresponding oscillatory mode. The purpose of the paper is to provide a solution for the optimal location of TCSC in order to achieve satisfactory performances regarding the power flow control and the damping of oscillations in power systems. Particularly interesting are problems that can occur during outage conditions. The proposed methods are investigated on realistic system.

R. Sadikovic

Papers

Application of FACTS devices for damping of power system oscillations

Self-tuning controller for damping of power system oscillations with FACTS devices

Towards Real-time Implementation of Adaptive Damping Controllers for FACTS Devices

A power flow control strategy for facts devices

Method for location of facts for multiple control objectives