Power Oscillation Damping Research Articles

Input/output selection for wide‐area power oscillation damper of hybrid multi‐terminal high‐voltage direct current to connect remotely located renewable energy resources

A hybrid multi-terminal HVDC (MTDC) scheme combines line commutated converter and voltage source converter technologies for HVDC transmission system. This study presents a comprehensive design of wide-area power oscillation damper (POD) controller for the hybrid MTDC system. The process consists of input/output selection and parameter tuning for the POD of the hybrid MTDC based on the linearised black-box model. The objective is to choose an effective control loop to damp the critical mode, which does not have negative impacts on the other modes in the system. For this purpose, a new index, named relative joint interaction index, is proposed for the input/output selection. Afterward, the parameter of POD is tuned using residue-based phase compensation technique because of its practical application. Finally, non-linear simulations are also carried out to verify the effectiveness of the designed POD in different loading conditions.

Control of PMSG-Based Wind Turbines for System Inertial Response and Power Oscillation Damping

This paper investigates an improved active power control method for variable speed wind turbine to enhance the inertial response and damping capability during transient events. The optimized power point tracking (OPPT) controller, which shifts the turbine operating point from the maximum power point tracking (MPPT) curve to the virtual inertia control (VIC) curves according to the frequency deviation, is proposed to release the “hidden” kinetic energy and provide dynamic frequency support to the grid. The effects of the VIC on power oscillation damping capability are theoretically evaluated. Compared to the conventional supplementary derivative regulator-based inertia control, the proposed control scheme can not only provide fast inertial response, but also increase the system damping capability during transient events. Thus, inertial response and power oscillation damping function can be obtained in a single controller by the proposed OPPT control. A prototype three-machine system containing two synchronous generators and a PMSG-based wind turbine with 31% of wind penetration is tested to validate the proposed control strategy on providing rapid inertial response and enhanced system damping.

Power System Oscillations Damping by Robust Decentralized DFIG Wind Turbines

This paper proposes a new robust decentralized power oscillation dampers (POD) design of doubly-fed induction generator (DFIG) wind turbine for damping of low frequency electromechanical oscillations in an interconnected power system. The POD structure is based on the practical 2 nd -order lead/lag compensator with single input. Without exact mathematical model, the inverse output multiplicative perturbation is applied to represent system uncertainties such as system parameters variation, various loading conditions etc. The parameters optimization of decentralized PODs is carried out so that the stabilizing performance and robust stability margin against system uncertainties are guaranteed. The improved firefly algorithm is applied to tune the optimal POD parameters automatically. Simulation study in two-area four-machine interconnected system shows that the proposed robust POD is much superior to the conventional POD in terms of stabilizing effect and robustness.

Application of Integrated Series Compensator in Damping Power Oscillations in Standalone Microgrids

This paper is concerned with power oscillation damping in standalone microgrids (MGs) using an integrated series compensator. Power oscillation is the result of dynamic interaction between generating units and/or loads in a power system, which results in increased losses, power quality degradation, and momentary overloading of the converters used in converter-based grid-connected microsources (MSs) in MGs. Designing an MS controller to mitigate these oscillations is not straightforward as other performance criteria may need to be compromised. The proposed structure employs a small series compensator to mitigate the oscillations. In this paper, the dependence of power/frequency variation is analytically shown. It is explained how by introduction of a series voltage, this dependence can be minimized. The derivation of the small-signal model used for eigenvalue analysis is briefly explained. To validate the modeling and show the performance and robustness of the proposed controller, time-domain simulations are used. Discussions on the size of the proposed compensator and also on using different control parameters are presented.

An Adaptive Power Oscillation Damping Controller by STATCOM With Energy Storage

This paper deals with the design of an adaptive power oscillation damping (POD) controller for a static synchronous compensator (STATCOM) equipped with energy storage. This is achieved using a signal estimation technique based on a modified recursive least square (RLS) algorithm, which allows a fast, selective, and adaptive estimation of the low-frequency electromechanical oscillations from locally measured signals during power system disturbances. The proposed method is effective in increasing the damping of the system at the frequencies of interest, also in the case of system parameter uncertainties and at various connection points of the compensator. First, the analysis of the impact of active and reactive power injection into the power system will be carried out using a simple two-machine system model. A control strategy that optimizes active and reactive power injection at various connection points of the STATCOM will be derived using the simplified model. Small-signal analysis of the dynamic performance of the proposed control strategy will be carried out. The effectiveness of the proposed control method to provide power oscillation damping irrespective of the connection point of the device and in the presence of system parameter uncertainties will be verified through simulation and experimental results.

A Quantitative Method to Determine ICT Delay Requirements for Wide-Area Power System Damping Controllers

This paper presents a quantitative method to determine delay requirements of the information and communication technology (ICT) system supporting wide-area power oscillation damping (WAPOD) controllers. An allowable time delay for the ICT infrastructure named “equivalent time delay (ETD)” is defined. The ETD is calculated by numerically comparing the damping behavior of the system when local input signals (LI) and remote input signals (RI) are used in the damping controller. The use of a WAPOD is only justified when its response outperforms that of a controller using local inputs. Therefore, the total time delay in the control loop must be below the calculated ETD. As such, the ETD serves as a design criteria to determine ICT latency requirements. The selection of an effective RI signal can be carried out by considering the maximum delays (ETDs) of different wide-area measurements. A damping improvement $ {\rm ETD}^{x~\%}$ has been proposed using the same methodology indicating a minimum outperformance of the remote signals. The proposed method is demonstrated using the well-known Klein-Rogers-Kundur multi-machine power system and the Vietnamese power system model.

Damping of interarea oscillations using electronic power transformer

This study utilizes the electronic power transformer (EPT) to enhance the damping of interarea oscillations in a multimachine power system based on active power modulation. The dynamic model of EPT is established, and decoupled vector control schemes of inner current control loops and outer active and reactive power control loops are modeled and designed. A power oscillation damper (POD) applied to the active power control loop of EPT is introduced to improve the stability of the power system. The POD controller parameters are designed based on the frequency response method. A study system based on the classical two-area four-machine system is built for damping controller design and time domain simulation, and the design procedures are presented in detail. The effectiveness of the designed POD controller is verified through eigenvalue analysis and time domain simulations. Copyright © 2014 John Wiley & Sons, Ltd.

The influence of GUPFC FACTS device on small signal stability of the electrical power systems

Abstract In this paper a power injection model is presented for the Generalized Unified Power Flow Controller (GUPFC), which facilitates its representation in the electric power system (EPS). This model of the GUPFC device becomes an attractive option to be implemented in power flow and optimal power flow programs. An efficient structure for the GUPFC control system is also presented in the article. This can be used to represent the dynamics in both stability analysis of small perturbations, which is the focus of this work, and in transient stability analysis (large disturbances) of the EPS. Considering the most basic GUPFC configuration, the proposed structure can control four active and reactive power flows in two lines, the voltage at the common installation bus; addition to these characteristics inherent in the GUPFC, this device can provide damping for the electromechanical oscillations of the EPS, as a POD (Power Oscillation Damping) controller is coupled to the control loop. Simulations are performed on one multimachine test system, whose results are analyzed and discussed in this paper, in order to analyze the performance of the power injection model and its proposed control structure in the damping of oscillations.

Energy-Storage-Based Low-Frequency Oscillation Damping Control Using Particle Swarm Optimization and Heuristic Dynamic Programming

Low-frequency oscillation is one of the main barriers limiting power transmission between two connected power sys- tems. Although power system stabilizers (PSSs) have been proved to be effective in damping inner-area oscillation, inter-area oscil- lation still remains a critical challenge in today's power systems. Since the low-frequency oscillation between two connected power systems is active power oscillation, power modulation through energy storage devices (ESDs) can be an efficient and effective way to maintain such power system stability. In this paper, we investigate the integration of a new goal representation heuristic dynamic programming (GrHDP) algorithm to adaptively control ESD to damp inter-area oscillation. A particle swarm opti- mization (PSO)-based power oscillation damper (POD) has also been proposed for comparison. Various simulation studies with residue-based POD controller design, the proposed PSO optimized controller design, and the GrHDP-based controller design over a four-machine-two-area benchmark power system with energy storage device have been conducted. Simulation results have demonstrated the efficiency and effectiveness of the GrHDP-based approach for inter-area oscillation damping in a wide range of system operating conditions. Index Terms—Energy storage device (ESD), goal representation heuristic dynamic programming (GrHDP), particle swarm opti- mization (PSO), power oscillation damper (POD), power system stability.

Fuzzy-Wavelet Based Double Line Transmission System Protection Scheme in the Presence of SVC

Increasing the power transfer capability and efficient utilization of available transmission lines, improving the power system controllability and stability, power oscillation damping and voltage compensation have made strides and created Flexible AC Transmission (FACTS) devices in recent decades. Shunt FACTS devices can have adverse effects on distance protection both in steady state and transient periods. Severe under reaching is the most important problem of relay which is caused by current injection at the point of connection to the system. Current absorption of compensator leads to overreach of relay. This work presents an efficient method based on wavelet transforms, fault detection, classification and location using Fuzzy logic technique which is almost independent of fault impedance, fault distance and fault inception angle. The proposed protection scheme is found to be fast, reliable and accurate for various types of faults on transmission lines with and without Static Var compensator at different locations and with various incidence angles.

Coordinated Robust Control of DFIG Wind Turbine and PSS for Stabilization of Power Oscillations Considering System Uncertainties

Uncertainties in power systems, such as intermittent wind power, generating and loading conditions may cause the malfunction of power system stabilizing controllers, which are designed without considering such uncertainties. To enhance the robustness of stabilizing controllers against system uncertainties, this paper proposes a new coordinated robust control of doubly fed induction generator (DFIG) wind turbine equipped with power oscillation damper (POD) and synchronous generator installed with power system stabilizer (PSS) for stabilization of power system oscillations. Without the difficulty of mathematical representation, the inverse output multiplicative perturbation is used to model system uncertainties. The structure of POD and PSS is specified as a practical second-order lead/lag compensator with single input. The parameters optimization of POD and PSS is conducted so that the stabilizing performance and robustness of POD and PSS are augmented. The improved firefly algorithm is applied to solve the optimization problem and achieve the POD and PSS parameters automatically. Simulation study in the modified IEEE-39 bus New England system included with DFIG wind turbines ensures that the robustness and stabilizing performance of the proposed coordinated DFIG with POD and PSS are much superior to those of the conventional DFIG with POD and PSS under various severe disturbances and system uncertainties.

Multivariable Self-Tuning Feedback Linearization Controller for Power Oscillation Damping

The objective of this brief is to design a measurement-based self-tuning controller, which does not rely on accurate models and deals with nonlinearities in system response. A special form of neural network (NN) model called feedback linearizable NN (FLNN) compatible with feedback linearization technique is proposed for representation of nonlinear power systems behavior. Levenberg-Marquardt (LM) is applied in batch mode to improve the model estimation. A time-varying feedback linearization controller (FBLC) is employed in conjunction with the FLNN-LM estimator to generate the control signal. Validation of the performance of proposed algorithm is done through the modeling and simulating both normal and heavy loading of transmission lines, when the nonlinearities are pronounced. Case studies on a large-scale 16-machine five-area power system are reported for different power flow scenarios, to prove the superiority of proposed scheme against a conventional model-based controller. A coefficient vector Λ for FBLC is derived and used online at each time instant, to enhance the damping performance of controller.

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

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.

Power Oscillation Damping Improvement by Adding Multiple Wind Farms to Wide-Area Coordinating Controls

This paper examines the feasibility of coordinating variable-speed wind farms with other power system devices, such as flexible ac transmission systems and synchronous generators, to damp low-frequency oscillations. For this purpose, an observer-based state-feedback approach is used to build a power oscillation damping (POD) controller, implemented through coordinated actions of multiple control devices, and able to manage several measurement channels. The wide-area POD controller also presents a time-delay compensation stage to mitigate adverse effects of latency involved in wide-area communication systems. Several practical issues are discussed and analyzed, such as measurement and control selection, model-order reduction, transmission time-delay compensation, impact of the POD control on wind farms, and robustness aspects. The control performance is evaluated and compared with other control schemes using eigenvalue analyses and nonlinear time-domain simulations over a wide range of operating conditions, for example, severe system faults, N - 1 outage contingencies, load/generation shedding, and line tripping.

Comparison and Assessment of a Multiple Optimal Coordinated Design Based on PSS and the STATCOM Device for Damping Power System Oscillations

The aim of this study is to present a comprehensive comparison and assessment of the damping function improvement for the multiple damping stabilizers using the simultaneously coordinated design based on Power System Stabilizer (PSS) and Static synchronous Compensator (STATCOM). In electrical power system, the STATCOM device is used to support bus voltage by compensating reactive power; it is also capable of enhancing the stability of the power system by the adding a supplementary damping stabilizer to the internal AC or DC voltage control channel of the STATCOM inputs to serve as a Power Oscillation Damping (POD) controller. Simultaneous coordination can be performed in different ways. First, the dual-coordinated design between PSS and STATCOM AC-POD stabilizer or DC-POD stabilizer is used. Then, coordination between the AC and DC STATCOM-based POD stabilizers are arranged in a single STATCOM device without PSS. Second, the coordinated design has been extended to triple multiple stabilizers among PSS, the AC-based POD and the DC-based POD in a Single Machine Infinite Bus (SMIB). The parameters of the multiple stabilizers have been tuned in the coordinated design by using a Chaotic Particle Swarm Optimization (CPSO) algorithm that optimized the given eigenvalue-based objective function. The simulation results show that the dual-coordinated design provide satisfactory damping performance over the individual control responses. Furthermore, the-triple coordinated design has been shown to be more effective in damping oscillations than the dual damping stabilizers.

Novel Comprehensive Control Framework for Incorporating VSCs to Smart Power Grids Using Bidirectional Synchronous-VSC

This paper presents a new control strategy for voltage-source converters (VSCs) in the frequency-angle domain which enables dc-link voltage regulation via frequency and load angle adjustment. A major advantage of the proposed controller is emulating the behavior of synchronous machines (SMs) with proper regulation of dc-link voltage which eases integration of VSCs interfacing distributed and renewable generation units into ac systems in the presence of conventional SMs. A cascaded frequency, angle and virtual torque control topology is developed to emulate the mechanical behavior of an SM which offers synchronization power to eliminate the need for a phase-locked-loop after initial converter synchronization, and damping power dynamics to damp power oscillations; and presents frequency dynamics similar to SMs, thus it introduces some inertia to the grid. The controller presents high stability margin and fast dc-link voltage regulation, whereas it can provide frequency support in the ac-side during contingencies. Frequency and voltage amplitude are adjusted by two separate loops. Two different variants are proposed for dc-link voltage control; namely direct dc-link voltage control and indirect dc-link voltage control via a dc-link voltage controller. Small-signal dynamics, analysis, and design process are presented. Both simulation and experimental results are provided to validate the controller effectiveness.

Input–output signal selection for damping of power system oscillations using wind power plants

During the last years wind power has emerged as one of the most important sources in the power generation share. Due to stringent Grid Code requirements, wind power plants (WPPs) should provide ancillary services such as fault ride-through and damping of power system oscillations to resemble conventional generation. Through an adequate selection of input–output signal pairs, WPPs can be effectively used to provide electromechanical oscillations damping. In this paper, different analysis techniques considering both controllability and observability measures and input–output interactions are compared and critically examined. Recommendations are drawn to select the best signal pairs available from WPPs to contribute to power oscillations damping. Control system design approaches including single-input single-output and multivariable control are considered. The recommendation of analysis techniques is justified through the tools usage in a test system including a WPP.

Automatic Tuning of PSSs and PODs Using a Parallel Differential Evolution Algorithm

Since Electric Power Systems are constantly subjected by perturbations, it is necessary to insert controllers for damping electromechanical oscillations originally from these perturbations. The Power System Stabilizer (PSS) and Power Oscillation Damper (POD) are two of the most common damping controllers used by the industry. However, just the inclusion of these controllers does not guarantee a satisfactory damping of the system, being necessary a good tune of them. This paper proposes a method for simultaneously tuning different kind of controllers considering several operation conditions at once. A differential evolution technique is used to perform the automatic tuning method proposed, with the great advantage of the parallel computing, since modern computers have more than one core. Simulation results with the benchmark test system New England/New York show the satisfactory performance of the parallel algorithm in a short running time than its non-parallel structure.

Residue-Based Evaluation of the Use of Wind Power Plants With Full Converter Wind Turbines for Power Oscillation Damping Control

As wind power plants (WPPs) gradually replace the power production of the conventional generators, many aspects of the power system may be affected, in which the small signal stability is included. Additional control may be needed for wind turbine generators (WTGs) to participate in the power oscillation damping. The feasibility of implementing this control needs to be assessed. This paper studies how the damping contribution of a WPP is affected by different operating conditions and its dependence to selected feedback signals. The WPP model used includes individual WTGs to study how internal changes may affect this contribution. The study is based on the changes suffered by the residues of the electromechanical modes, which indicate the sensitivity of the modes to this particular feedback. The results show that a park level control for the entire WPP is possible, although it may not provide damping for a range of critical operating conditions.

Performance of PSS to Damp Power Oscillations Caused by an HVDC Link in AC-DC Power System

HVDC (High Voltage Direct Current) systems are increasingly being applied to improve power system operation and controllability. However, inappropriate setting of HVDC controller may have a detriment effect on the system performance. Generally, PSS (Power System Stabilizer) is known as a simple concept, easy to perform, and computationally effective to enhance damping of power system oscillations through excitation control of synchronous generator. This paper examines the effectiveness of the PSS to enhance the dynamic performance of AC-DC power systems and to compensate the negative damping of HVDC system. The dynamic performance is evaluated by examining the system response to various disturbances. In order to ensure the reliability of the simulation test results as well as the performance of the PSS, detailed HVDC modeling is adopted using SimPowerSystems toolbox in the MATLAB, and some important conclusions are drawn.