Power Oscillation Damping Controller Research Articles

Improvement of an AC microgrid system’s stability by using a fuzzy logic-based PSS controller

This research article presents the low-frequency oscillation damping control of an AC Microgrid. It is integrated with four distributed generation units in which two DGs are renewable energy source based solar PV and wind energy using DFIG and the other two DGs are conventional synchronous generator-based hydro and diesel generators. There is insufficient generation through renewable-based DG then a diesel generator is employed as an emergency unit to fulfil the requirements and maintain and control the deviation of the frequency of the system. The use of renewable-based DG affected the system's dynamic stability and the characteristics of an integrated microgrid differ from conventional sources of generation. This investigation explores the impression of the deployment of multiple forms of the power oscillation damping (POD) controllers to distributed generation sources of grid forming AC Microgrid. The main various types of POD controllers are conventional lead-lag PSSs, MBPSS-4B, and proposed robust fuzzy logic PSS (FLPSS) controllers are implemented on distributed generation units of AC Microgrid for the elimination of low-frequency oscillation. Low oscillation frequencies between 0.1 and 2 Hz are the focus of this work. The system's damping ratios and stability margins because of MG integration are observed using eigenvalues analysis. The results of the simulation test demonstrate the accomplishment of the robust fuzzy logic PSS controller regarding conventional lead-lag PSSs and the MBPSS-4B controller during circumstances of fault.

Centralised Multimode Power Oscillation Damping Controller for Photovoltaic Plants With Communication Delay Compensation

Centralised Multimode Power Oscillation Damping Controller for Photovoltaic Plants With Communication Delay Compensation

Adaptive inter-area power oscillation damping from offshore wind farm and MMC-HVDC using deep reinforcement learning

The coordination of the offshore wind farm (OWF) and high-voltage direct current (HVDC) links to provide ancillary power oscillation damping (POD) services may become a mandatory requirement from the transmission system operators in the near future. However, the performances of the POD controllers (PODCs) are vulnerable to the power system uncertainties and random communication delays of the wide-area signals. To address these issues, this paper proposes the design of the coordinated PODCs by using the deep reinforcement learning (DRL) method. The DRL-based PODCs employ one of the state-of-the-art DRL algorithms, proximal policy optimization, which can learn to adapt to the system uncertainties and time-varying communication delays by interacting with the power system continuously. A detailed simulation model of an OWF connected to the IEEE-39 bus AC grid via the modular multilevel converter based HVDC link has been built as a simulation platform, and the efficacy of the proposed DRL-based PODCs has been validated across a broad spectrum of operating conditions, disturbances, and communication latency.

Simultaneous Power Oscillation Damping and Frequency Control in AC Microgrid Considering Renewable Uncertainties: A Coordinated Control of Multiple Robust Controllers with Imperfect Communication

Simultaneous Power Oscillation Damping and Frequency Control in AC Microgrid Considering Renewable Uncertainties: A Coordinated Control of Multiple Robust Controllers with Imperfect Communication

Phase-leg power equalization method of modular multilevel converter with APOD strategy under unbalanced fault condition

An active power oscillation damping (APOD) control is one of the representative unbalanced fault compensation strategies. Recently, various studies have been performed on the effect of the APOD with the internal power dynamic analysis of a Modular Multilevel Converter (MMC); however, most of the papers have considered only the active power component for analyzing the internal dynamics of the MMC. During the APOD operation, while reactive power is supplied to the grid for the voltage compensation, phase-leg power imbalance can be aggravated. To enhance stability and reliability, the phase-leg power imbalance phenomenon should be sufficiently considered at the development stage of the controller. This research discovers that the phase-leg power imbalance rate could be determined by the magnitude and phase of the negative sequence component of the grid voltage and the amount of reactive power. In addition, the unbalanced power component can be accurately calculated only based on the grid voltage information and the reactive power reference. Also, this paper proposes a phase-leg power equalization method (PPEM) using unbalanced power component estimation. Furthermore, an improved control structure is also proposed to achieve more accurate phase-leg power equalization using the internal leg-energy dynamics analysis. The effectiveness of the proposed methods is verified through high-fidelity PSCAD/EMTDC time-domain simulations using Point-to-Point (PTP) MMC-HVDC system and Hardware-in-the-Loop Simulation (HILS) with the MMC-MVDC system.

Power oscillation damping method suitable for network reconfigurations based on converter interfaced generation and combined use of active and reactive powers

Power system stabilisers (PSSs) are commonly used in synchronous generators for damping low-frequency oscillations. However, many of these machines have been replaced by converter-interfaced generators (CIGs), such as those used in solar power plants. This means that CIG-based power plants should also contribute to oscillation damping. Moreover, CIGs may use both active and reactive power for power oscillation damping (POD). However, their combined use has been seldom studied in the literature. Moreover, only a few articles have addressed the adaption of POD controllers when the power system changes (e.g., after a fault). In this paper, a POD controller for CIG-based power plants is proposed that is suitable for operation in power systems exposed to reconfiguration. This controller takes advantage of both active and reactive power injection to maximise the damping of the power system. This controller is based only on local measurements so communication systems are not required. Theoretical developments were validated in a laboratory using real power converters including a 75 kVA grid emulator where the two-area benchmark model is emulated and four 15 kVA CIGs operating in parallel connection. The applicability of the proposed controller was also explored for the IEEE 39-bus system.

A Recent Review on Approaches to Design Power System Stabilizers: Status, Challenges and Future Scope

Modern power system networks are complex and subjected to several uncertainties. Due to the complexity and uncertainties involved in power system operation, the networks are prone to instabilities. Rotor-angle instability is one such issue that, if not addressed properly, may lead to system collapse. A power system stabilizer (PSS) is primarily a power oscillation damping (POD) controller used to dampen power oscillations, thereby improving rotor angle stability. The proper design of PSSs is a challenging task and is essential for the secure and reliable operation of power systems. In the past, many power system instability events occurred, resulting in cascading failures and even blackouts. In the literature, several methods are proposed for the efficient design of PSSs or POD controllers. In this contribution, a recent review on the design of PSS is presented, along with challenges and the future scope of research in this field. On the basis of this review, it can be concluded that there is ample scope for designing PSS in a more efficient and robust manner, considering several uncertainties that may occur during the operation of modern power systems.

Coordination of Utility-scale PV Plant and Wind Power Plant in Interarea-Oscillation Damping

This paper proposes a coordinated control scheme of a utility-scale photovoltaic (PV) power plant and a wind power plant (WPP) to support voltage stability and provide fast recovery after the grid faults in a power system with high penetration renewable energy sources (RES). <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">The operation of PV and wind plants are time-shifted by approximately twelve hours. PV generates during the daytime, and wind plants usually produce peak power at night. Seasonally, the PV plants generate peak power on summer days, and wind plants produce maximum power during winter nights. These characteristics present an opportunity to use both types of renewables to complement each other in producing power and transforming energy, and also in providing active damping to safeguard the power system. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">To achieve these goals, two separate power oscillation damping (POD) control loops have been included for active and reactive power modulation in both PV and WPP. In both PV and WPP, an active power damping function without any power curtailment and a reactive power damping function modulating the reactive current (<i>I</i>_Q) on the voltage control loop have been included. This paper uses the nearest synchronous generator's local bus angle and speed as feedback for each of these loops. The performance of the proposed coordinated scheme based on the time of the day has been verified in a two-area system using the PSCAD simulator. The effectiveness of the control schemes has been investigated during the different timings of the day by observing the efficiency and the response time of the post-fault oscillations mitigation and the voltage restoration.

Power oscillation damping control using PI-neuron network controller for distributed generator grid connection with MVDC

Distributed generator (DG) connection to the system with the DC grid called medium voltage direct current (MVDC) grid connection has received attention and gradually integrated into the distribution grid. The linear controller, such as the PI controller, usually uses the MVDC grid control for power oscillation damping. The PI controller is limited and does not show satisfactory results when the load and parameters of the system itself are changed. This paper proposes the PI with neuron network (NN) as a feed-forward controller (PINNF) to improve the control of the DG grid connection with the MVDC. The proposed PINNF controller is applied to control the power oscillation damping. Since the NN can estimate the proper feed-forward control signals in each situation to the control system, the proposed PINNF controller performs better than the conventional PI controller. The effectiveness of the proposed PINNF controller is validated using nonlinear dynamic simulations on the MATLAB/Simulink program. Four case tests are presented and discussed in this paper. Results indicate the improvement of power oscillation damping stability and performance in the MVDC grid connection with the proposed PINNF controller.

Stability and Dynamic Analysis of the PMSG-Based WECS With Torsional Oscillation and Power Oscillation Damping Capabilities

The direct-drive permanent-magnet synchronous generator (PMSG) based wind energy conversion system (WECS) with a soft drivetrain shaft is vulnerable to torsional oscillation when it participates in power oscillation damping (POD) services for the AC grid. This paper investigates three possible scenarios of incorporating both torsional oscillation damping (TOD) and POD controllers into PMSG-based WECS. A model of a PMSG-based offshore wind farm (OWF) connected to the IEEE 39-bus AC grid is developed and utilized to analyze the stability and dynamic performances of the WECS within these three scenarios. Comprehensive modal analysis is carried out to analyze the interaction between the torsional and power oscillations, and to tune the TOD and POD controllers to damp these oscillations simultaneously in each scenario. Furthermore, the dynamic performances of the PMSG-based WECS within these scenarios are evaluated through time-domain simulations. Then an optimal scenario for PMSG-based WECS to damp both oscillation types with close frequencies is identified, which is modulating the DC-link voltage for the TOD and the grid-side active power for the POD. This result can provide useful guidance for the future industrial application of the TOD and POD control in the PMSG-based WECS.

Mayfly Optimization Algorithm Applied to the Design of PSS and SSSC-POD Controllers for Damping Low-Frequency Oscillations in Power Systems

In this paper, it is proposed to apply the mayfly optimization algorithm (MOA) to perform the coordinated and simultaneous tuning of the parameters of supplementary damping controllers, i.e., power system stabilizer (PSS) and power oscillation damping (POD), that actuate together with the automatic voltage regulators of the synchronous generators and the static synchronous series compensator (SSSC), respectively, for damping low-frequency oscillations in power systems. The performance of the MOA is compared with the performances of the genetic algorithm (GA) and particle swarm optimization (PSO) algorithm for solving this problem. The dynamics of the power system is represented using the current sensitivity model, and, because of that, a current injections model is proposed for the SSSC, which uses proportional-integral (PI) controllers and the residues of the current injections at the buses, obtained from the Newton–Raphson method. Tests were carried out using the New England system and the two-area symmetrical system. Both static and dynamic analyses of the operation of the SSSC were performed. To validate the proposed optimization techniques, two sets of tests were conducted: first, with the purpose of verifying the performance of the most effective algorithm for tuning the parameters of PSSs, PI, and POD controllers, and second, with the purpose of performing studies focused on small-signal stability. The results have validated the current injections model for the SSSC, as well as have indicated the superior performance of the MOA for solving the problem, accrediting it as a powerful tool for small-signal stability studies in power systems.

Coordinated design of PSS and STATCOM-POD based on the GA-PSO algorithm to improve the stability of wind-PV-thermal-bundled power system

The application of renewable energy has a significant impact on the stability of power systems. This article jointly uses static synchronous compensator (STATCOM), additional power oscillation damping (POD) controller and power system stabilizers (PSSs) to improve the stability of power systems in transmission network. An enhanced intelligent optimization algorithm is utilized to optimize the controller parameters. The proposed algorithm introduces the idea of combined genetic algorithm (GA) and particle swarm algorithm (PSO) to overcome the local convergence problem of the PSO. The voltage control and damping control of STATCOM are comprehensively considered in the objective function to suppress low-frequency power oscillation (LFO) while ensuring the effectiveness of voltage control. Numerical results from the IEEE 4 machine 2 area system and the IEEE 16-machine five-areas system demonstrate the effectiveness of the proposed method and the superiority on restraining the LFO of the wind-PV-thermal-bundled (WPTB) system.

Damping inter‐area oscillation using reinforcement learning controlled TCSC

Inter-area oscillation is a serious problem that threatens a power system. Appropriate damping control of the inter-area oscillation would ensure the grid stability and maintain the tie-line power transfer capability. In this paper, a novel reinforcement learning (RL) based power oscillation damping (POD) controller is proposed that uses Thyristor Controlled Series Compensators (TCSC) to damp inter-area oscillations. By leveraging the unbiased gradient direction estimation of the natural evolution strategy (NES), the power flows on the tie-lines were successfully regulated and inter-area oscillations were damped through dynamically modulating the inserted reactance of the TCSC. Furthermore, parallel computation techniques were adopted to speed up the training process of the NES. The proposed RL-based POD controller has been tested on both two-area four-machine system and North American MinniWECC system. Extensive studies have demonstrated the excellent performance of the proposed RL-based TCSC POD controller in damping inter-area oscillations.

A Comprehensive Review of Small-Signal Stability and Power Oscillation Damping through Photovoltaic Inverters

This paper focuses on the methods that ensure the rotor angle stability of electric power systems, which is most frequently analyzed with small-signal models. Over the past several decades, power system stabilizers (PSSs) for conventional excitation systems were the main tools for improving the small-signal stability of electromechanical oscillatory modes. In the last decade, power oscillation damping (POD) control implemented in photovoltaic (PV) inverters has been considered an alternative to PSSs. As PV generation undergoes massive rollout due to policy directions and renewable energy source integration activities, it could potentially be used as a source of damping, which is crucial for sustaining the rotor angle stability of the remaining in-service synchronous generators. Several studies have already been dedicated to the development of different damping strategies. This paper contributes to the existing research in power system stability by providing a comprehensive review of the effects of PV generation on small-signal stability, as well as the recent evolution of POD control through PV inverters. The features and impacts of the various ways to realize POD controllers are assessed and summarized in this paper. Currently, detailed information and discussions on the practical application of PV inverter PODs are not available. This paper is, thus, intended to initiate a relevant discussion and propose possible implementation approaches concerning the topic under study.

Electromechanical interactions of full scale converter wind turbine with power oscillation damping and inertia control

In this paper, the impacts of power oscillation damping (POD) and inertia controller on the structural system of wind turbine (WT) are evaluated. Synchronous generators (SGs) fitted with well-established power system stabilisers (PSS) are declining leading to reduced power system inertia and damping capability which are critical to system stability performance. The WTs will become more dominant and should therefore be capable of providing inertia response and POD to maintain system performance. However, there has been some concern amongst the industry regarding effects of inertia and POD controls on WT performance when the active power modulation is utilised by both controllers particularly during frequency event that leads to low-frequency power oscillations. A detailed grid-connected full-scale converter (FSC)-WT system which combines aerodynamic, electrical, and mechanical characteristics was developed to assess its interactions with the POD and inertia controllers and also the resulting impact on the WT structural system. The obtained results show that the implementation of the POD/inertia controllers on the FSC-WT can improve the inertia response and oscillation damping but will affect the dynamics of its drivetrain, blades, and tower. However, these effects are shown to be smaller than the effects caused by the credible electricity system faults.

Damping of Low-Frequency Oscillations in Power Systems by Large-Scale PV Farms: A Comprehensive Review of Control Methods

Global warming and the desire to increase the use of clean energy have led to increasing the installation and operation of renewable energy power plants (REPPs), especially large-scale photovoltaic (PV) farms (LPFs). Given that the LPFs are added to power system or replace conventional power plants, they must be able to perform the basic tasks of synchronous generators (SGs). One of these tasks is the ability to mitigate the low-frequency oscillation (LFO) risk. Also, one of the LPFs problems is reducing the power system inertia and increasing the risk of LFOs. Therefore, these types of power plants must damp the LFOs through a power oscillation damping controller (PODC), similar to the performance of power system stabilizers (PSSs) in the SGs. This paper represents an overview of the different PODCs and control methods for LFOs damping by LPF. It seems that it can be a driver for future studies. Different studies show that the application of PODCs for LPFs can play an effective role to damp the LFOs and increase the power system stability.

Forecasting of solar potential and investigation of voltage stability margin using facts device: a synopsis from geography of things perspective

The uncertain and erratic nature of renewable energy in solar form is quite laborious to integrate into conventional system operation. In the first part, machine-learning algorithm is used to train models on solar irradiance data and different meteorological weather information to predict solar irradiance. The above-mentioned data is taken from publicly available Geographical Information System (GIS) data. This can be realistically collected using Internet of Things (IoT) devices and sensors which, if based on a GIS approach transforms the system into Geography of Things (GoT). Again, the intermittent and inertia-less nature of PV systems can produce significant power oscillations problems. In the second part, it is shown that residue-based power oscillation damping (POD) controller significantly improves the inter-area oscillation damping. This report overall puts an in-depth analysis with regard to the challenges of solar resources with the integrating, planning, operation and particularly the stability of the power grid.

Optimal coordinated design of PSS and UPFC-POD using DEO algorithm to enhance damping performance

Low-frequency oscillations (LFO) are an inevitable problem of power systems and they have a great effect on the capability of transfer and power system stability. The power system stabilizers (PSSs) as well as flexible AC transmission system (FACTS) devices can help to damp LFO. The target of this study is to tackle the problem of a dual-coordinated design between PSS and unified power flow controller (UPFC) implementing the task of power oscillation damping (POD) controller in a single machine infinite bus (SMIB) system. So, dolphin echolocation optimization (DEO) technique is utilized as an optimization tool to search for optimal parameter tunings based on objective function for enhancing the dynamic stability performance for a SMIB. DEO an algorithm has a few parameters, simple rules, provides the optimum result and is applicable to a wide range of problems like other meta-heuristic algorithms. Use DEO gave the best results in damping LFO compared to particle swarm optimization (PSO) algorithm. From the comparison results between PSO and DEO, it was shown that DEO provides faster settling time, less overshoot, higher damping oscillations and greatly improves system stability. Also, the comparison results prove that the multiple stabilizers show supremacy over independent controllers in mitigationg LFO of a SMIB.

Incorporation of active power ancillary services into VSC-HVDC connected energy sources

This paper investigates the interaction between frequency containment services (FCS) and power oscillation damping (POD) ancillary services installed in a Voltage Source Converter High Voltage DC (VSC-HVDC) line. In VSC-HVDC systems, ancillary services can be installed to maintain appropriate levels of power system stability. Both FCS and POD controllers are typically installed in the active power control loop separately. The modulation signals generated by these two ancillary services both affect the active power injected by the converter. When operating a VSC with FCS and POD ancillary services the resultant combination of the modulation signals in the active power loop may result in reduced performance. The results in this study show that performance of controllers reduces when both ancillary services are activated, particularly in low-inertia systems. Modifications to the control structures of both controllers that improve their performance under various disturbances are proposed.

Effects of POD Control on a DFIG Wind Turbine Structural System

This paper investigates the effects power oscillation damping (POD) controller could have on a wind turbine structural system. Most of the published work in this area has been done using relatively simple aerodynamic and structural models of a wind turbine which cannot be used to investigate the detailed interactions between electrical and mechanical components of the wind turbine. Therefore, a detailed model that combines electrical, structural and aerodynamic characteristics of a grid-connected Doubly Fed Induction Generator (DFIG) based wind turbine has been developed by adapting the NREL (National Renewable Energy Laboratory) 5 MW wind turbine model within FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. This detailed model is used to evaluate the effects of POD controller on the wind turbine system. The results appear to indicate that the effects of POD control on the WT structural system are comparable or less significant as those caused by wind speed variations. Furthermore, the results also reveal that the effects of a transient three-phase short circuit fault on the WT structural system are much larger than those caused by the POD controller.