Characteristics Of Power System Research Articles

Stabilization of the output characteristics of an inductive power system for equipment in hospital wards

Stabilization of the output characteristics of an inductive power system for equipment in hospital wards

An overview of grid-forming technology and its application in new-type power system

To address the global climate crisis, achieving energy transitions is imperative. Establishing a new-type power system is a key measure to achieve CO2 emissions peaking and carbon neutrality. The core goal is to transform renewable energy resources into primary power sources. The large-scale integration of high proportions of renewable energy sources and power electronic devices will dramatically change the operational mechanisms and control strategies of power systems. Existing wind and solar converters mostly adopt the grid-following control mode, which leads to significant challenges in system security and stability as it is insufficient to support the frequency and voltage of the grid. On the other hand, grid- forming control technology (GFM) can provide voltage and frequency support for the system, and thus becomes an effective measure to improve the inertia and damping characteristics of power systems. This paper illustrates the principles, control strategies, equipment types, application scenarios, and project implementation of grid-forming technology. The simulation and analysis based on a renewable-dominated real new-type power system show that GFM can significantly enhance the frequency and voltage support capacity of the power system, improve renewable energy accommodation capacity and grid transmission capacity under weak grid conditions, and play an important role in enhancing the stability and power supply reliability of renewable-dominated new-type power systems.

Coordinated Control of Transient Voltage Support in Doubly Fed Induction Generators

The large-scale integration of wind power significantly alters the voltage dynamic characteristics of power systems. Wind turbines have a weak ability to withstand grid disturbances and have difficulty in providing effective reactive power support during transient periods. The sensitivity of wind turbines to the grid voltage significantly increases the probability of large-scale, cascading off-grid events. This paper proposes a coordinated control strategy to enhance the transient reactive power support capability of doubly fed wind farms. The additional stator current demagnetization control reduces the risk of a crowbar protection action after a fault and ensures that the unit power is controllable. Based on the voltage–reactive power coupling relationship, each unit can produce reactive power according to the voltage–reactive power sensitivity matrix during the transient period. After the reactive power output of the unit reaches the limit, transient active and reactive combined control is further adopted to reduce the active power output of the unit to a certain extent and improve the reactive power support capability. Finally, two cases are built in the PSCAD to verify the effectiveness of the proposed control strategy. The results show that the proposed control strategy can enable the wind farm to output more reactive power to the grid during the transient period, effectively supporting the system voltage during the transient process and avoiding further deterioration of the fault.

Review of Existing Tools for Software Implementation of Digital Twins in the Power Industry

Digital twin technology is an important tool for the digitalization of the power industry. A digital twin is a concept that allows for the creation of virtual copies of real objects that can be used for technical state analysis, predictive analysis, and optimization of the operation of power systems and their components. Digital twins are used to address different issues, including the management of equipment reliability and efficiency, integration of renewable energy sources, and increased flexibility and adaptability of power grids. Digital twins can be developed with the use of specialized software solutions for designing, prototyping, developing, deploying, and supporting. The existing diversity of software requires systematization for a well-informed choice of digital twin’s development tool. It is necessary to take into account the technical characteristics of power systems and their elements (equipment of power plants, substations and power grids of power systems, mini- and microgrids). The reviews are dedicated to tools for creating digital twins in the power industry. The usage of Digital Twin Definition Language for the description data of electromagnetic, thermal, and hydrodynamic models of a power transformer is presented.

Study on the Evolutionary Process and Balancing Mechanism of Net Load in Renewable Energy Power Systems

With the rapid development of renewable energy sources such as wind and solar, the net load characteristics of power systems have undergone fundamental changes. This paper defines quantitative analysis indicators for net load characteristics and examines how these characteristics evolve as the proportion of wind and solar energy increases. By identifying inflection points in the system’s adjustment capabilities, we categorize power systems into low, medium, and high renewable energy penetration. We then establish adjustment models that incorporate traditional coal power, hydropower, natural gas generation, adjustable loads, system interconnections, pumped-storage hydroelectricity, and new energy storage technologies. A genetic algorithm is employed to optimize and balance the net load curves under varying renewable energy proportions, analyzing the mechanism behind net load balance. A case study, based on real operational data from 2023 for a provincial power grid in western China, which is rich in renewable resources, conducts a quantitative analysis of the system’s adjustment capability inflection point and net load balancing strategies. The results demonstrate that the proposed method effectively captures the evolution of the system’s net load and reveals the mechanisms of net load balancing under different renewable energy penetration levels.

Аdaptive Сontrol algorithm Based on a Virtual Synchronous Generator. Part II

An increase in the penetration level of power plants based on renewable energy sources using power converters (PCs) has a direct impact on the dynamic characteristics of modern electric power system (EPS) and, as a consequence, the nature of the transient processes. One of the main problems in such EPS is a significant change in the magnitude of the total inertia of the system over time, which leads to an increase in the rate of change of frequency and the magnitude of its maximum deviation under various disturbances. A promising direction for solving this problem is the synthesis of new structures of PC control systems based on a virtual synchronous generator (VSG) with adaptively changing parameters. The results of the research in this area are presented in the paper, which consists of two parts. In the first part of the paper, the dependence of the adaptive algorithms efficiency for controlling the parameters of the VSG on the structure used is substantiated. A comparative analysis of the developed modified VSG structure with traditional algorithms is performed and its fundamental advantages are proved. The second part of the article presents an analysis of the influence of the modified structure parameters of the VSG on the dynamic response using time domain transient analysis. Based on the results obtained, adaptive algorithms for independent control of virtual inertia and parameters of the VSG damper winding have been developed. The performed mathematical modeling confirmed the reliable and efficient operation of the developed adaptive control algorithms and the modified structure of the VSG as a whole. From the theoretical and experimental results obtained in the paper, it follows that there is a need for simultaneous development and improvement of adaptive control algorithms and the VSG structures used for this.

Novel pilot protection for transmission lines with large-scale wind farms based on trajectory distance characteristics

In terms of integrating large-scale wind farms into power systems, the fault characteristics of power systems have undergone fundamental changes, potentially leading to the rejection and misoperation of traditional protections. To address these issues, a time-domain pilot protection based on trajectory distance characteristics is proposed. A novel trajectory distance calculation method is introduced to improve the one-way distance (OWD) algorithm, which is used as a metric to quantify the distance between current trajectories to identify internal and external faults. To overcome the adverse impact of nonideal conditions, a metric, namely the ratio of nonsimultaneous points is proposed. Faults are identified using two metrics. Validation results from PSCAD/EMTDC and hardware-in-the-loop platform demonstrate that the proposed protection can operate within 15 ms in most cases and has excellent robustness against diverse nonideal conditions, including tolerating noise with 10 dB signal-to-noise ratio. Moreover, it considerably outperforms traditional and new differential protection methods.

A Low voltage AC fault arc detection method based on multi-feature fusion

Abstract The complex electrical environment makes it difficult for most arc detectors on the market to accurately detect faulty arcs. A universal fault arc detection method based on machine learning (ML) algorithms is proposed in this paper. To address the potential hazards of fault arcs in the power system, firstly, the causes, time-domain, and frequency-domain characteristics of fault arcs were analyzed. Then, an arc experiment platform was built according to national standards, and current data was collected under various load conditions. Finally, the arc detection model was trained based on ML. The main contribution of this study is to explore a feature combination that is not affected by load type interference and has strong generalization ability for identifying fault arcs, clarify the key factors and feature extraction methods for identifying fault arcs, and develop a set of high-precision arc detection methods, providing strong guarantees for the stable operation of the power system.

New Electric Power System Stability Evaluation Based on Game Theory Combination Weighting and Improved Cloud Model

The development of new electric power system is a requirement for China to realize its “carbon peaking and carbon neutrality goals”, so it is of great importance that we assess the stability of a new electric power system under certain conditions. Firstly, according to the factors affecting the stability of the new power system, the characteristics of the new electric power system are analyzed in depth, so as to establish a stability evaluation index system including four first-level indices of safety, adequacy, flexibility, and adaptability. Secondly, a stability evaluation model is proposed. Based on the game theory, the entropy weight method, criteria importance though intercrieria correlation (CRITIC) method, and coefficient of variation method are combined and assigned, and the cloud model is improved through the combination of weights, which is used for evaluating the stability of the new electric power system. Finally, the applicability of the proposed evaluation model is verified by an arithmetic example analysis, which can identify the vulnerability of the new electric power system and provide suggestions for improving its stability. The model can provide a theoretical basis for promoting energy transition and sustainable development.

A Comprehensive Review of Alarm Processing in Power Systems: Addressing Overreliance on Fault Analysis and Projecting Future Directions

This paper reviews alarm processing methods in electrical power systems, focusing on evolving strategies beyond traditional fault analysis to accommodate modern grid complexities. Historically, alarm processing has predominantly aimed at fault analysis, increasingly merging with technological advances in communication and computing. However, it still needs to fully meet the challenges posed by the dynamic characteristics of modern power systems. This review points out certain inadequacies in current practices, notably their limited adaptation to new grid conditions. The authors propose a novel generation of alarm processing methodologies designed for future grids, emphasizing managing rare events and enhancing operator decision-making through advanced anomaly detection and explainable artificial intelligence. This synthesis presents a prospective direction for future research and applications in alarm processing, advocating for methodologies better suited to supporting system operators amidst technological advancements.

Real-time transient stability early warning system using Graph Attention Networks

In this paper, a classifier based early warning system is designed, trained and tested based on time-series of Phasor Measurement Unit (PMU) measurements at all buses in a power system. The classifier is based on a novel combination of Graph Attention Networks and Long Short-Term memories, and is trained to label power system data in the form of captured windows of PMU measurements. These labels are then used to provide early warning for transient instability. The classifier is trained and tested data from simulations of the Nordic44 test system, and includes extensive topological variations under two different load levels. It is found that accurate early warnings can be provided, but the quality of prediction is highly dependent on specific power system characteristics, such as how quickly the power system responds to transient disturbances.

Research on the analysis method of power system relay protection action characteristics based on fault recording data

The action characteristics of power system relay protection devices can well analyze whether the relevant actions are correct. An analysis method of relay protection action characteristics in power system based on fault recording data is designed. After analyzing the relay device structure and protection action characteristics and requirements, the power system relay protection action record data recorded by the fault recorder; The second order RC low-pass filter is used to preprocess the recorded data; The filtered data is input into the analysis model of relay protection action characteristics based on SVM algorithm. The SVM algorithm classifies whether the relay protection action characteristics recorded by the filtered fault recording data meet the expectations, and completes the analysis of power system relay protection action characteristics. The experimental results show that this method can effectively analyze the operation characteristics of power system relay protection, and can accurately check whether the relay protection device can operate correctly.

Analysis of frequency characteristics of power system with wind farm-energy storage coordinated inertial control

With the increasing penetration level of wind power in the power system, the decoupling of wind turbine rotor speed and system frequency has led to the loss of the inertia of wind farms (WF), which can no longer be neglected. With the continuous development of energy storage (ES) technology, WF-ES coordinated inertial control has attracted attention as an effective means for wind turbines (WT) to participate in inertia response. How to build a WF-ES coordinated inertial control strategy and analyze system frequency characteristics has become a key research issue. In this paper, the frequency response model of a power system with WF-ES is established using the system frequency characteristic analysis method. The wind speed zones of the WF are taken into account, and different WF-ES control schemes are adopted under different wind speeds, aiming to ensure the active participation of WTs in the system frequency process across all wind speed conditions and effectively prevent frequency secondary drop. Finally, a power system frequency response simulation model is built in Matlab/Simulink to analyze the frequency characteristics of the power system with WF-ES coordinated inertial control and verify the feasibility of the proposed WF-ES coordinated inertial control strategy under various wind speeds.

A Review of the Research on the Wide-Band Oscillation Analysis and Suppression of Renewable Energy Grid-Connected Systems

With the continuous expansion of the scale of power generated by grid-connected renewable energy, the form and operation characteristics of power grids have undergone significant changes, and the power electronic characteristics of power systems are prominent, resulting in the frequent occurrence of wide-band oscillation problems when renewable energy power generation equipment is connected to a power grid. Oscillation has the characteristics of nonlinearity and has an oscillation frequency ranging from a few hertz to several thousand hertz or more, which seriously threatens the stable operation of power grids. This paper summarizes the wide-band oscillation events that occur worldwide under the background of renewable energy access to power grids, classifies the wide-band oscillation events according to the distribution of oscillation frequency bands, and sorts out the characteristics of various oscillations. From the perspectives of the source side and network side, the existing oscillation suppression measures are classified and prospected.

Exploration of carbon reduction in new municipal power systems

In response to China’s goal of “carbon peak and carbon neutrality”, a large number of new energy sources are connected to the power grid, and Chinese cities are also accelerating the construction of new power systems led by new energy. Taking Lishui City as an example, this paper constructs a low-carbon emission reduction evaluation system to evaluate the carbon reduction effectiveness of the new power system. This paper first introduces the basic technical characteristics of the new power system, and introduces in detail the key technologies involved in the construction of the new power system in Lishui. Then, the projects implemented by Lishui City in promoting the new power system and the current achievements were briefly summarized. After that, a new electric carbon traceability model of Lishui power system was constructed to carry out carbon traceability and carbon tracking for the municipal power grid. Finally, a low-carbon emission reduction evaluation system was constructed, and a number of evaluation indicators were proposed to evaluate the carbon reduction effectiveness of Lishui’s new power system, and the zero-carbon evaluation index was calculated through the historical data of Lishui, and the results showed that the new power system in Lishui City achieved remarkable results in carbon reduction and emission reduction.

Analysis of Factors Affecting Sub-Synchronous Oscillation in Doubly-Fed Wind Power Grid-Connected System Based on Impedance Sensitivity and Research on Suppression Strategy

Aiming at the matter of sub-synchronous oscillation (SSO) of the doubly-fed induction generator (DFIG) series compensation capacitors grid connection, a SSO suppression strategy based on adding damping controllers in rotor-side converter (RSC) is put forwarded. Considering the control parameters of power and current control loops of RSC, the equivalent impedance model of DFIG series compensation grid connection (SCGC) is established, and then combined with the equivalent RLC resonant circuit of the system, the mechanism and factors of SSO are analyzed by impedance method. Calculating the impedance sensitivity of the system impedance to parameters by sensitivity analysis method, so as to identify the leading factor affecting the SSO characteristics of wind power system. Combined with the stability criterion of system impedance characteristics, the parameters are adjusted to meliorate system stability. Based on the leading factor affecting the SSO and the mechanism of the SSO, the damping controllers are added in the RSC to supply positive damping for the system to eliminate the negative damping brought by the RSC and rotor resistance, thus suppressing the SSO of the system. The validity of the put forwarded suppression strategy is proved through PSCAD/EMTDC simulation.

Frequency Control and Optimal Operation of Low-Inertia Power Systems With HVDC and Renewable Energy: A Review

With the integration of large-scale renewable energy sources (RES) and high voltage direct current (HVDC) based inter-regional transmission, modern power systems are facing low-inertia issues and poor frequency regulation capabilities. This paper conducts a comprehensive review on frequency control and optimal operation methods in this context. First, the frequency characteristic of a low-inertia power system is analyzed covering the whole frequency response process. Secondly, the impacts of RES and HVDC integration on system inertia and frequency performance are studied, and the system frequency characteristics considering RES and HVDC are analyzed. Then, the frequency response modes of various frequency regulation resources are compared from the perspective of “source-grid-load-storage”, including their basic control principles and frequency control strategies. Further, from the operation dispatch perspective, the frequency security-constrained power system optimal operation methods are reviewed. Finally, future research trends in this area are discussed.

Inertial issues in renewable energy integrated systems and virtual inertia techniques

The global proliferation of renewable energy drastically altered the characteristics of power systems. Integration of clean energy sources reduces the inherent rotational inertia, making the system precarious and susceptible to various disturbances. The major challenges encountered are fast frequency fluctuations, voltage fluctuations, high rate of change of frequency (RoCoF), and frequency nadir. In order to address and adapt to a future low-inertia scenario, it is crucial to understand the effect of inertia on various parameters. This paper introduces a comprehensive review of the fundamental aspects of inertia and challenges that arise due to the reduction in inertia. Researchers have tackled this issue by employing various virtual inertia (VI) emulation techniques, which also have been extensively reviewed in the literature along with their merits, limitations, and recent developments. The impact of RES penetration on system dynamics is analyzed by simulating an IEEE-9 bus system with renewable energy source (RES) in MATLAB/Simulink. Furthermore, a three-phase fault is also introduced, to emphasize the effect of reduced inertia by observing the rotor angle and frequency deviation. The results validate that RES integration and fault location are observed to have a significant impact on stability parameters, making them extremely unstable.

Life Cycle Assessment of Energy Storage Technologies for New Power Systems under Dual‐Carbon Target: A Review

Aiming at the grid security problem such as grid frequency, voltage, and power quality fluctuation caused by the large‐scale grid‐connected intermittent new energy, this article investigates the life cycle assessment of energy storage technologies based on the technical characteristics and performance indicators. First, the new power system under dual‐carbon target is reviewed, which is compared with the traditional power system from the generation side, grid side, and user side. Based on the power characteristics of the new power system, the energy storage mechanism and energy storage characteristics of mechanical energy storage, electrochemical energy storage, chemical energy storage, electromagnetic energy storage, and thermal energy storage are described. Then, compared with the existing research strategies, a comprehensive life cycle assessment of energy storage technologies is carried out from four dimensions: technical performance, economic cost, safety assessment, and environmental impact. Moreover, the suitable scenarios and application functions of various energy storage technologies on the power generation side, grid side, and user side are compared and analyzed from the working principle, key technologies, advantages and disadvantages, and technical difficulties of energy storage technologies. Finally, combined with the energy storage technologies in the electricity market, four profit models are analyzed.

Unraveling fundamental properties of power system resilience curves using unsupervised machine learning

Power system is vital to modern societies, while it is susceptible to hazard events. Thus, analyzing resilience characteristics of power system is important. The standard model of infrastructure resilience, the resilience triangle, has been the primary way of characterizing and quantifying resilience in infrastructure systems for more than two decades. However, the theoretical model provides a one-size-fits-all framework for all infrastructure systems and specifies general characteristics of resilience curves (e.g., residual performance and duration of recovery). Little empirical work has been done to delineate infrastructure resilience curve archetypes and their fundamental properties based on observational data. Most of the existing studies examine the characteristics of infrastructure resilience curves based on analytical models constructed upon simulated system performance. There is a dire dearth of empirical studies in the field, which hindered our ability to fully understand and predict resilience characteristics in infrastructure systems. To address this gap, this study examined more than two hundred power-grid resilience curves related to power outages in three major extreme weather events in the United States. Through the use of unsupervised machine learning, we examined different curve archetypes, as well as the fundamental properties of each resilience curve archetype. The results show two primary archetypes for power grid resilience curves, triangular curves, and trapezoidal curves. Triangular curves characterize resilience behavior based on three fundamental properties: 1. critical functionality threshold, 2. critical functionality recovery rate, and 3. recovery pivot point. Trapezoidal archetypes explain resilience curves based on 1. duration of sustained function loss and 2. constant recovery rate. The longer the duration of sustained function loss, the slower the constant rate of recovery. The findings of this study provide novel perspectives enabling better understanding and prediction of resilience performance of power system infrastructure in extreme weather events.