The electric power system is currently undergoing a period of unprecedented changes. Environmental and sustainability concerns lead to replacement of a significant share of conventional fossil fuel-based power plants with renewable energy resources. This transition involves the major challenge of substituting synchronous machines and their well-known dynamics and controllers with power electronics-interfaced generation whose regulation and interaction with the rest of the system is yet to be fully understood. In this article, we review the challenges of such low-inertia power systems, and survey the solutions that have been put forward thus far. We strive to concisely summarize the laid-out scientific foundations as well as the practical experiences of industrial and academic demonstration projects. We touch upon the topics of power system stability, modeling, and control, and we particularly focus on the role of frequency, inertia, as well as control of power converters and from the demand-side.

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Foundations and Challenges of Low-Inertia Systems (Invited Paper)

The utilization of power electronic inverters in power grids has increased tremendously, along with advancements in renewable energy sources. The usage of power electronic inverters results in the decoupling of sources from loads, leading to a decrease in the inertia of power systems. This decrease results in a high rate of change of frequency and frequency deviations under power imbalance that substantially affect the frequency stability of the system. This study focuses on the requirements of inertia and the corresponding issues that challenge the various country grid operators during the large-scale integration of renewable energy sources. This study reviews the various control techniques and technologies that offset a decrease in inertia and discusses the inertia emulation control techniques available for inverters, wind turbines, photovoltaic systems, and microgrid. This study attempts to explore future research directions and may assist researchers in choosing an appropriate topology, depending on requirements.

Future low-inertia power systems: Requirements, issues, and solutions - A review

Thank you for reading statistical signal processing detection estimation and time series analysis. Maybe you have knowledge that, people have look hundreds times for their chosen novels like this statistical signal processing detection estimation and time series analysis, but end up in harmful downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they juggled with some malicious bugs inside their laptop.

Statistical Signal Processing Detection Estimation And Time Series Analysis

There is an increasing interest and research effort focused on the analysis, design and implementation of distributed control systems for AC , DC and hybrid AC / DC microgrids. It is claimed that distributed controllers have several advantages over centralised control schemes, e.g., improved reliability, flexibility, controllability, black start operation, robustness to failure in the communication links, etc. In this work, an overview of the state-of-the-art of distributed cooperative control systems for isolated microgrids is presented. Protocols for cooperative control such as linear consensus, heterogeneous consensus and finite-time consensus are discussed and reviewed in this paper. Distributed cooperative algorithms for primary and secondary control systems, including (among others issues) virtual impedance, synthetic inertia, droop-free control, stability analysis, imbalance sharing, total harmonic distortion regulation, are also reviewed and discussed in this survey. Tertiary control systems, e.g., for economic dispatch of electric energy, based on cooperative control approaches, are also addressed in this work. This review also highlights existing issues, research challenges and future trends in distributed cooperative control of microgrids and their future applications.

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Distributed Control Strategies for Microgrids: An Overview

Electric power systems foresee challenges in stability due to the high penetration of power electronics interfaced renewable energy sources. The value of energy storage systems (ESS) to provide fast frequency response has been more and more recognized. Although the development of energy storage technologies has made ESSs technically feasible to be integrated in larger scale with required performance, the policies, grid codes and economic issues are still presenting barriers for wider application and investment. Recent years, a few regions and countries have designed new services to meet the upcoming grid challenges. A number of grid-scale ESS projects are also implemented aiming to trial performance, demonstrate values, and gain experience. This paper makes a review on the above mentioned aspects, including the emerging frequency regulation services, updated grid codes and grid-scale ESS projects. Some key technical issues are also discussed and prospects are outlined.

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Fast Frequency Response From Energy Storage Systems—A Review of Grid Standards, Projects and Technical Issues

Inertia reduction due to high-level penetration of converter interfaced components may result in frequency stability issues This paper proposes and analyzes different strategies using synchronous condenser (SC), synthetic inertia (SI) of wind power plant, and their combination to enhance the frequency stability of low-inertia systems under various scenarios and wind conditions Furthermore, one of the SC models includes hardware of automatic voltage regulator (AVR) for better representation of the reality is implemented The simplified Western Danish power system simulated in real-time digital simulator is used as a test system of low inertia to demonstrate the effectiveness of the strategies The comparative results show that the combination of SC with AVR hardware-in-the-loop test and SI offers a better improvement not only on frequency stability (rate of change of frequency and frequency deviation) but also on the system synchronism under various operating conditions

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Combination of Synchronous Condenser and Synthetic Inertia for Frequency Stability Enhancement in Low-Inertia Systems

In order to meet the energy demand and at the same time to achieve sustainable development objectives on a global scale, the Danish government has set a long-term strategy of fossil fuel free country by the year 2050. However, the decline of conventional power generation units and a rising amount of converter interfaced components (wind turbine, HVDC, and Photovoltaic) may have negative effects on the stability of the power system. These components do not have enough inertia response to control frequency excursion, so the power grid can depend on few synchronous machines for frequency regulation and reduce the system inertia. Consequently, the frequency stability of the system will be easily jeopardized. To address these issues, the paper studies frequency characteristics of future Western Danish renewable-based system that uses a majority of wind turbine generators. Different scenarios of wind turbine penetration, governor responsibility of synchronous generators, and disturbance are simulated to examine the impact of high-level renewable energy integration on the system frequency characteristics. The effect of synchronous condensers for the frequency stability enhancement is investigated. It can be concluded from the comparative simulation results that synchronous condenser demonstrates a satisfactory performance for improving the system frequency stability.

Frequency stability improvement of low inertia systems using synchronous condensers

High-level integration of renewable energy sources in power system leads to the displacement of conventional generators and consequently challenges in power system frequency stability are introduced. To mitigate the negative impact of significant wind power penetration in the grid on the frequency stability, this paper proposes supplementary control methods to implement synthetic inertia for doubly-fed induction generator (DFIG) based wind energy system during frequency excursions. Different control strategies and activation schemes are analyzed and implemented on the Western Danish renewable-based system using-real time digital simulator (RTDS) to propose the best one for the synthetic inertia controller. From the comparative simulation results, it can be concluded that the method using a combination of both the frequency deviation and derivative as input signals, and the under-frequency trigger provides the best dynamic response in term of the system frequency stability improvement.

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Frequency stability enhancement for low inertia systems using synthetic inertia of wind power

The rapid increase of converter-based generation in grids causes significant changes in system dynamic characteristics. These changes require verification and testing of the reliability, optimization, and functionality of power system elements and controllers, which become more important for guaranteeing a secure operation. This paper first introduces a hardware-in-the-loop setup of an automatic voltage regulator (AVR) control system and then proposes a software-in-the-loop (SiL) setup for the parameterization of an IEEE standard AVR/excitation system model and a power oscillation damping (POD) controller of synchronous condenser. The AVR hardware is interfaced with a simulated grid in real-time digital simulator (RTDS) using EMT simulation to evaluate its control functions. Parameter optimization for the POD and the AVR simulation model by SiL simulation is implemented in a closed loop between RTDS and MATLAB/Simulink interfaced through OPC to satisfy the optimization objectives. By the tests executed on the future Western Danish power system, parameter optimization of the POD and IEEE standard AVR model, and the function of AVR hardware are successfully implemented and verified.

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Hardware- and Software-in-the-Loop Simulation for Parameterizing the Model and Control of Synchronous Condensers

This paper presents an approach to extend the capabilities of smart grid laboratories through the concept of Power Hardware-in-the-Loop (PHiL) testing by re-purposing existing grid-forming converters. A simple and cost-effective power interface, paired with a remotely located Digital Real-time Simulator (DRTS), facilitates Geographically Distributed Power Hardware Loop (GD-PHiL) in a quasi-static operating regime. In this study, a DRTS simulator was interfaced via the public internet with a grid-forming ship-to-shore converter located in a smart-grid testing laboratory, approximately 40 km away from the simulator. A case study based on the IEEE 13-bus distribution network, an on-load-tap-changer (OLTC) controller and a controllable load in the laboratory demonstrated the feasibility of such a setup. A simple compensation method applicable to this multi-rate setup is proposed and evaluated. Experimental results indicate that this compensation method significantly enhances the voltage response, whereas the conservation of energy at the coupling point still poses a challenge. Findings also show that, due to inherent limitations of the converter’s Modbus interface, a separate measurement setup is preferable. This can help achieve higher measurement fidelity, while simultaneously increasing the loop rate of the PHiL setup.

https://www.mdpi.com/1996-1073/13/15/3770/pdf

Ha Thi Nguyen

Papers

Combination of Synchronous Condenser and Synthetic Inertia for Frequency Stability Enhancement in Low-Inertia Systems

Frequency stability improvement of low inertia systems using synchronous condensers

Frequency stability enhancement for low inertia systems using synthetic inertia of wind power

Hardware- and Software-in-the-Loop Simulation for Parameterizing the Model and Control of Synchronous Condensers

Distributed Power Hardware-in-the-Loop Testing Using a Grid-Forming Converter as Power Interface