Electromechanical Oscillations Research Articles

Small‐signal rotor angle stability of multi‐virtual synchronous machine (n‐VISMA) microgrid

AbstractAutonomous microgrid is known to lack appropriate inertia and damping for grid stabilization. Due to this, virtual synchronous machine (VISMA) has been introduced to provide necessary ancillary services through control of power converters. In a multi‐VISMA (n‐VISMA) microgrid, relative rotor angle stability of the power system is dependent on the active power balance after small perturbation. Thus, the use of relevant analytical models are essential issues for microgrid stability analysis. This paper presents a comprehensive small‐signal stability analysis to study inherent electromechanical oscillations in the virtual rotors. The subsystems of the microgrid consisting of VISMA, network, load and the outer power control were all modelled in Synchronous Reference Frame. The small‐signal model (SSM) was tested on IEEE‐9 bus system with VISMA replacing electromechanical synchronous machines on the network. To validate the developed numerical analytics, dynamic responses of the SSM are compared with those of the non‐linear (NL) system dynamics and the results reveal that the developed linearized SSM is sufficient to accurately characterize behaviour of the VISMA microgrid when operated in autonomous mode. Eigenvalues analysis and parameter sensitivities of the critical modes were investigated. Oscillatory participations of the VISMAs and steady state stability limit of the microgrid have also been investigated.

Optimizing power system stability: A hybrid approach using manta ray foraging and Salp swarm optimization algorithms for electromechanical oscillation mitigation in multi‐machine systems

AbstractThis paper emphasizes the significance of ensuring adequate damping of electromechanical oscillations in power systems to ensure stable operation. Power System Stabilizers (PSSs) are influential in enhancing system damping and refining dynamic characteristics during transient conditions. However, the efficacy of PSSs is notably contingent on parameter values, particularly in the case of lead‐lag PSSs. In response to this challenge, the paper introduces a Tilt‐Integral‐Derivative (TID)‐based PSS, optimized through a novel optimization algorithm called Hybrid Manta Ray Foraging and Salp Swarm Optimization Algorithms (MRFOSSA). The MRFOSSA algorithm demonstrates robustness and enhanced convergence, validated through benchmark function tests, and outperforms competing algorithms. These superior characteristics of MRFOSSA were employed in optimal tuning of TID‐PSSs to uphold the stability of multi‐machine power systems. The MRFOSSA algorithm demonstrates robustness and enhanced convergence, outperforms competing algorithms in the optimal tuning of TID‐PSS within the Western System Coordinating Council (WSCC)‐3‐machines 9‐bus test system. In summary, the proposed TID‐PSS, coupled with the MRFOSSA algorithm, presents a promising avenue for enhancing power system stability.

Modified Multimachine Power System Design with DFIG-WECS and Damping Controller

Rotor angle stability, which involves electromechanical oscillation damping and control, is very important in maintaining the stability of modern power grid systems. Renewable energy sources like wind energy are undergoing massive integration into modern power grid systems to meet energy demands and decarbonize power grid systems of carbon emissions from fossil fuel generators. To enable increased integration of wind renewable energy sources, precise models are needed for research and analytical purposes. Wind renewable energy is generated through a wind energy conversion system (WECS); one such conversion system is the doubly fed induction generator (DFIG) system. In this study, a precise model of a DFIG-WECS was modeled and integrated into the IEEE’s two-area Kundur power test system, which represents the available power grid system, and is also a multimachine power system using the Matlab/Simulink 2023 software. A damping controller known as the power system stabilizer (PSS), whose optimal parameters were obtained using artificial eco-system optimization (AEO), was also incorporated into the integrated power grid system to control and damp electromechanical oscillations. The results showed that the PSS damping controller effectively damped electromechanical oscillations in the integrated power grid system.

Dynamic Patterns in the Small-Signal Behavior of Power Systems with Wind Power Generation

This paper investigates the dynamic patterns in the small-signal behavior of power systems with wind power generation. The interactions between synchronous generators and wind generators are investigated. In addition, the impact of increased wind generation penetration on the damping and frequency of the synchronous generator’s electromechanical oscillations is addressed. Wind generators of three different technologies are considered throughout this study. Very detailed dynamic models of wind generators are used and detailed.

Adaptive Hierarchical Fractional-Order Sliding Mode Control Strategy for Multi-terminal VSC-HVDC System with Wind Farm

In this paper, an adaptive hierarchical fractional-order sliding mode controller (AHFSMC) for a multi-terminal Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) Integrated with a wind farm (WF) system is designed. Multi-terminal VSC-HVDC (MtVDC) connected to wind farms has received several attentions in the power sector because of its numerous benefits. The effectiveness of MtVDC, on the other hand, is dependent on the control scheme used. To achieve this goal, a hierarchical sliding mode control method by fractional-order calculus is used. The controller parameters are adjusted according to a suitable adaptation method to enhance the proposed controller's robustness compared to the system uncertainties coefficient. An appropriate Lyapunov-based approach is used to achieve the adaptation rule. This paper discusses a scheme to design additional controllers in MtVDC systems to damp electromechanical oscillations, one of several features of HVDC presently under active study. Numerical simulations validate the proposed control strategy's feasibility and efficiency. This novel approach is employed for the upgrading of system stability with the dynamic properties of the MtVDC in a variety of operative conditions.

Ambient data-driven participation factors related to oscillation modes based on subspace dynamic mode decomposition

Analyzing the connection between the variables participating in the oscillation and modes in electromechanical oscillation is particularly important for maintaining system stability. This paper proposes an ambient data-driven method based on Subspace Dynamic Mode Decomposition (Sub-DMD) to extract the Participation Factors (PFs) related to system state and algebraic variables in electromechanical oscillation modes. This method uses ambient data to calculate the low-dimensional approximate matrix of the system, and the PFs is extracted by using eigen-decomposition and mode energy. Compare the extracted PFs with the results of power generation dispatch. The effectiveness of the proposed method is demonstrated by using simulation data from IEEE 4-generator 2-area test system and IEEE 16-generator 68-bus test system.

Analysis and Mitigation of Electromechanical Oscillations in Drivetrain for Hybrid Synchronization Control of DFIG-Based Wind Turbines

Analysis and Mitigation of Electromechanical Oscillations in Drivetrain for Hybrid Synchronization Control of DFIG-Based Wind Turbines

Validating the measurement of passive Musculo-articular wrist stiffness without intentional or reactive contraction using axillary plexus block

BackgroundPassive stiffness describes how easily a joint may move passively. To accurately measure wrist stiffness, an electro-oscillation device was developed. The objectives were to 1) ensuring that the measurement are free from intentional or reflex contraction, 2) analyzing how forearm anatomy affects the passive stiffness of the wrist and 3) determining the clinical practical relevance of the device. MethodsIn this prospective study, the device generated low amplitude sinusoidal motions in flexion and extension on the wrist to quantify elastic and viscous passive stiffness in voluntary orthopaedic patients. The first series of measurements was carried out in the state of voluntary relaxation, the second series of measurements was carried out after an axillary plexus anesthetic block. A matched group of healthy subjects were use for control. FindingsThe Electromechanical Oscillation methods effectively enable the measurement of passive joint stiffness since the stiffness values obtained show no statistically significant difference pre-post the anesthesia. The stiffness values are comparable to those of healthy subjects. The effect of forearm passive structure, estimated by the perimeter of the forearm, influences the passive stiffness of the wrist, mainly the viscous component. InterpretationThe use of sinusoidal oscillation was well accepted by the participants, demonstrating its usefulness and applicability in a clinical setting. This work serves as a foundation for future investigations of orthopaedic and/or neurological pathological conditions characterized by abnormal passive joint stiffness of the wrist. It paves the way for its use as a diagnostic, prognostic, and monitoring tool in these pathologies.

Out-of-Step Detection based on Phasor Measurement Unit

The electrical power systems operate as a huge, interconnected network that extends across a large area. In the power system, there is an equilibrium between generated power and a load. Any disturbance in the system, such as a fault or a change in load, will lead to imbalance and electromechanical oscillations. As a result, the power flow between two areas varies. This is known as a power swing." Large system disturbances could lead to large rotor angle deviations between groups of generators, resulting in a loss of synchronism between generators or between interconnected systems. This is known as an out-of-step condition. To avoid equipment damage and power outages, the interconnected area must be isolated as soon as possible before the electrical system loses synchronization. In this paper, PMU data is used to measure the current, voltage, and phase angle of the three phases at both ends of two interconnected area power systems. The measured data is then used to distinguish between a power swing or fault condition and predict the future phase angle difference during the disturbances to evaluate the system stability condition. If a swing is detected, then it will be ascertained whether the swing is stable or not. The performance of the proposed method has been tested on a simulated system using MATLAB / Simulink software.

A coordinated modelling and control of modified pumped storage governor with unified power flow controller to damp low frequency oscillations in power system for stochastic renewable penetrations

A modern power system network is more susceptible to oscillatory instability problem due to power oscillations caused by uncertain penetration of renewable sources. Also, pumped storage hydro power generation (PSHPG) is going to take important role for energy storage and management with varying renewable penetrations, but their governors need to be utilized efficiently for power oscillation damping. In this work a coordinated modified pumped storage governor with fractional parallel unified power flow controller (FPUPFC) has been modelled and controlled to damp angular frequency variations in power system. The prime objective of this work is to enhance efficacy of pumped storage hydro turbine governors integrated into an expert system with UPFC to take part in electromechanical oscillation damping. Here the governor is modified by fractional order PID action with additional phase compensation and in FPUPFC both series and shunt converters are controlled simultaneously by parallel fractional lead-lag based control action. The power system considered here consists of hydro generators of 100 MVA with 90.94 MW rated turbine output power with different operating conditions for two area 4 generators and 39 bus 10 generators multimachine renewable integrated system. It has been observed that efficacy of pumped storage hydro turbine governor action has been much improved when coordinated with FPUFC control action. A new hybridized modified differential evolution with fractional particle swarm optimization (MDEFPSO) is proposed to tune the parameters of proposed controller, with a multi-objective function considering variation in speed and real power deviations, settling time, overshoot and undershoot of system response.

Small-Signal Analysis and Enhanced Control of Large-Scale PV-Penetrated Power Systems From the Electromechanical Oscillations Point of View

Small-Signal Analysis and Enhanced Control of Large-Scale PV-Penetrated Power Systems From the Electromechanical Oscillations Point of View

Multi-Machine Power System Transient Stability Enhancement Utilizing a Fractional Order-Based Nonlinear Stabilizer

Given the intricate nature of contemporary energy systems, addressing the control and stability analysis of these systems necessitates the consideration of highly large-scale models. Transient stability analysis stands as a crucial challenge in enhancing energy system efficiency. Power System Stabilizers (PSSs), integrated within excitation control for synchronous generators, offer a cost-effective means to bolster power systems’ stability and reliability. In this study, we propose an enhanced nonlinear control strategy based on synergetic control theory for PSSs. This strategy aims to mitigate electromechanical oscillations and rectify the limitations associated with linear approximations within large-scale energy systems that incorporate thyristor-controlled series capacitors (TCSCs). To dynamically adjust the coefficients of the nonlinear controller, we employ the Fractional Order Fish Migration Optimization (FOFMO) algorithm, rooted in fractional calculus (FC) theory. The FOFMO algorithm adapts by updating position and velocity within fractional-order structures. To assess the effectiveness of the improved controller, comprehensive numerical simulations are conducted. Initially, we examine its performance in a single machine connected to the infinite bus (SMIB) power system under various fault conditions. Subsequently, we extend the application of the proposed nonlinear stabilizer to a two-area, four-machine power system. Our numerical results reveal highly promising advancements in both control accuracy and the dynamic characteristics of controlled power systems.

Method to Quantify Modal Interactions Between Converter Interfaced Generators and Synchronous Generators

The aim of this paper is to quantify the interactions between the oscillation modes of power systems within the realm of small-signal stability. This paper focuses on the interactions between Converter Interfaced Generator (CIG) oscillation modes and electromechanical oscillation modes of Synchronous Generators (SGs). It is difficult to determine the modal interactions using the existing analysis such as mode sensitivity, mode loci and participation factors. This paper proposes an extension to eigenvalue sensitivity analysis in order to determine the interaction between modes and impact of the interaction on system stability. Interaction coefficients are proposed to quantify the interaction between the modes. A modified IEEE 39-bus system with CIGs is considered to carry out the proposed analysis. The analysis is carried out to investigate the impact of PLL parameters on the interaction among the oscillation modes. The analysis is also carried out considering renewable energy penetration levels of 50-70%. It is observed that the interaction between CIG and electromechanical modes of SG results in increased participation of SGs' states in CIG modes. This increased participation of SG states in CIG modes results in reduced damping of oscillations in SG states.

Optimal fractional SSSC auxiliary controller for power system low frequency oscillations damping improvement

This work presents a new controller design to improve inter-area low frequency electromechanical oscillations (LFEOs) damping and enhance the overall stability of the electrical network. The control strategy used the static synchronous series compensator (SSSC) based flexible AC transmission systems (FACTS) series-type device mainly performed for power flow and voltage regulation. Then, a fractional order proportional integral derivative (FOPID) is introduced as an auxiliary controller for the SSSC using the difference of rotor speed deviations of generators as input signal to improve the oscillations damping. Moreover, genetic algorithm (GA) is applied to seek for optimum controller gains. The proposed control approach is examined on two-area four-machine (2A4M) test system. The FOPID performance is compared with the integer order proportional integral derivative (PID). Obtained results show that the proposed SSSC-based FOPID controller achieves high performance for enhancement of inter-area low frequency oscillations damping.

An improved dynamic mode decomposition for real‐time electromechanical oscillation monitoring in power systems: The impact of ultra‐low frequency modes and its removal strategy

AbstractThe growing complexity of power systems, driven by the increasing use of renewable energy sources, necessitates efficient real‐time monitoring of electromechanical oscillations, which is crucial for enhancing grid security. Dynamic Mode Decomposition (DMD) is a promising data‐driven method for addressing this challenge of monitoring the electromechanical oscillations, made possible by power system digitalization. However, DMD implementation faces unresolved issues, including the impact of ultra‐low‐frequency modes (ULFM) on accuracy due to trends caused by their excitation. While larger data windows can mitigate this, they slow down oscillation estimation. ULFM characteristics remain poorly studied. This study conducts a comprehensive ULFM analysis and proposes a solution by combining DMD with a high‐pass filter to counter ULFM's adverse effects on accuracy. This allows for a reduction in DMD's window size, significantly improving computational efficiency. Simulations on three test systems demonstrate that the enhanced DMD offers faster computation and superior accuracy compared to the traditional DMD method.

Multi‐objective precise phasor measurement locations to assess small‐signal stability using dingo optimizer

AbstractSmall‐signal stability is an important task and key research in electrical engineering for networks. This research article focuses on the implementation of a multi‐objective approach for choosing an optimal location for Phasor Measurement Units (PMUs) to quantify a power system's small‐signal stability by maximizing the signal‐to‐noise ratio (SNR) in the system. The novelty of this research lies in the implementation of Dingo Optimization (DOX) technique along with the Prony Analysis (PA) approach for the assessment of small‐signal stability in standard grid networks. The voltage angle, amplitude and the range of frequencies are measured by the optimal placement of PMUs, which primarily focus on the multi‐signal PA. To achieve the objective of this research, DOX integrated with the multi‐signal PA approach is used to determine the ideal position for PMU placement by considering maximum redundancy and optimizing the signal to noise ratio to a maximum level. The effectiveness of the DOX strategy is established with improved accuracy and fewer disturbances by optimizing the electromechanical oscillations of the system. The implementation of the DOX approach for attaining the best value of the maximized SNR is obtained by analyzing a wide set of conditions, perturbations, and additive noise, which provides an accurate assessment of damping ratio (DR) and frequency (f) of electromechanical oscillations. Numerical results obtained from the standard IEEE test systems (14, 39, 57, 118, and 300 bus systems) are compared with the existing methods in the literature. The statistical indices demonstrate that under the highly limited optimization context selected, the intended optimizer functions satisfactorily.

Small signal stability and dynamic performance investigation on multi-machines power system including DFIG wind farm

<p>The boundless potential of wind power in augmenting global energy production is a promising prospect. The efficient design and cost-effectiveness of doubly fed induction generator (DFIG) wind systems make them an optimistic solution for incorporating wind power on a massive scale. However, integrating these systems into power grids poses several challenges, including power system stability. This study examines the small signal stability and dynamic performance of a modified Western System Coordinating Council (WSCC) 9-bus system including a DFIG wind farm using load flow analysis, and both electromechanical oscillations and eigenvalue analysis. Three case studies were conducted based on the DFIG location and power increment.The simulation is carried out with the aid of the power system analysis toolbox (PSAT) that operates within the MATLAB environment. The study’s findings suggest that the perturbation and location of the DFIG relative to the system’s load have a minimal influence on the overall system’s stability and efficiency. However, when considering damping ratio, power angle, and rotor speed deviations, generators 1 and 2 with the perturbed DFIG installed on bus 8 are the most sensitive units to instability. Hence, larger perturbations and different DFIG’s location influence on power systems necessitates further analysis.</p>

DESIGN AND IMPLEMENTATION OF CONTROL STRATEGIES FOR SMALL-SIGNAL STABILITY IN DOUBLY FED INDUCTION GENERATOR BASED WIND TURBINES USING MATLAB SIMULINK

A majority of the wind turbines in use today's variable speed energy systems are double fed induction generators. We went over the goals and methods used in onshore horizontal axis wind energy turbine control. Design and implementation of control the model for the simulation and the analysis of a double-fed induction generator. Among the various technologies available for wind energy conversion the DFIG is one of the preferred solution because it offers the advantage of reduced mechanical stress and optimized power capture to variable speed operation. To facilitate the electrical production control, the separated control of active and reactive powers of such as machine is considered. The results of simulations realized under the MATLAB /Simulink software are analyzed and interpreted. Keywords--- Damping, electromechanical oscillations; power system; small-signal stability; synchronous generators, double fed induction generator. Wind energy conversion system

Development of the equivalent Great Britain 36-zone power system for frequency control studies

This paper presents a dynamic model of the equivalent Great Britain (GB) 36-zone power system, which can be used for reliable and realistic assessment of emerging load frequency control mechanisms. Flexible architecture of the presented dynamic test system permits a broad range of security of supply and small-signal stability studies for design of future power grids. It can be particularly useful for academic research, but also for undertaking feasibility studies in power industries. The proposed dynamic test system, which is obtained through network reduction of the original full-scale GB transmission power system developed by National Grid Electricity System Operator (NGESO) Company, provides detailed information about the GB power system. In this regard, the required data and modelling approaches to develop the 36-zone system are provided in detail. The presented dynamic test system represents the system topology, impedance characteristics and electromechanical oscillations of the original GB power system however, it is not an exact equivalent of the master GB system. Illustrative dynamic models of the key system components, including synchronous generators, automatic voltage regulators, power system stabilizers, hydro and steam turbines models along with speed governing systems are presented. Dynamic behavior of 36-zone test system in response to infeed loss contingencies is investigated. Particularly, the impact of changes in the system inertia on the system electromechanical modes is examined using the modal analysis approach. In this context, the mode shape concept is employed to determine dominant generators and contribution of different zones in the low frequency oscillations. Moreover, time-domain simulations are undertaken to validate the modal analysis results. Additionally, the condition of different zones from the viewpoint of frequency nadir and maximum rate of change of frequency for various contingencies and extreme cases are examined.

Transient stability versus damping of electromechanical oscillations in power systems with embedded multi‐terminal VSC‐HVDC systems

AbstractMulti‐terminal high‐voltage direct current technology based on voltage‐source converter stations (VSC‐MTDC) is expected to be one of the most important contributors to the future of electric power systems. In fact, among other features, it has already been shown how this technology can contribute to improve transient stability in power systems by the use of supplementary controllers. Along this line, this paper will investigate in detail how these supplementary controllers affect electromechanical oscillations, by means of small‐signal stability analysis. The paper analyses two control strategies based on the modulation of active‐power injections (P‐WAF) and reactive‐power injections (Q‐WAF) in the VSC stations which were presented in previous work. Both control strategies use global signals of the frequencies of the VSC‐MTDC system and they presented significant improvements on transient stability. The paper will provide guidelines for the design of these type of controllers to improve both large‐ and small‐disturbance angle stability. Small‐signal stability analysis (in Matlab) has been compared with non‐linear time domain simulation (in PSS/E) to confirm the results using CIGRE Nordic32A benchmark test system with a VSC‐MTDC system. The paper analyses the impact of the controller gains and communication latency on electromechanical‐oscillation damping. The main conclusion of the paper is that transient‐stability‐tailored supplementary controllers in VSC‐MTDC systems can be tuned to damp inter‐area oscillations too, maintaining their effectiveness.