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14 pages, 2543 KiB

Open AccessArticle

Research on a Two-Layer Optimal Dispatching Method Considering the Mutual Aid of Peak Regulating Resources among Regional Power Grids

by Tianmeng Yang, Suhua Lou, Meng Zhang, Yanchun Li, Wei Feng and Jicheng Liu

Energies 2024, 17(3), 667; https://doi.org/10.3390/en17030667 - 30 Jan 2024

Viewed by 424

Abstract

Since the power generation structures and load characteristics in each province in China are quite different, the distribution of peak regulating resources and demands are extremely imbalance. Restricted by a low power marketization degree, peak regulating resource shortages, and transmission channel blocks, the [...] Read more.

Since the power generation structures and load characteristics in each province in China are quite different, the distribution of peak regulating resources and demands are extremely imbalance. Restricted by a low power marketization degree, peak regulating resource shortages, and transmission channel blocks, the efficient utilization of new energy is facing greater pressures. In order to improve the mutual aid in regional power grids and to obtain more precise simulation results, this paper proposes a two-layer optimization dispatching model, considering the mutual aid of peak regulation resources between each province. It determines the optimal startup mode and the units’ power output in each province and obtains the power output arrangements for all the units and the technical and economic indicators. The model and the solution method are original and innovative. And it effectively solved the unequal distribution problem between the peak regulating demands and resources of each provincial power grid. Finally, taking an actual regional power grid in China as an example, the simulation results show that the proposed model can significantly improve the utilization rate of new energy, which verifies the effectiveness and feasibility of the proposed model and methods presented in this paper. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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16 pages, 359 KiB

Open AccessArticle

Fuzzy Inference System Development for Turbogenerator Failure Diagnosis on Floating Production Offloading and Storage Platform

by Patricio F. Castro, George Rossany Soares de Lira, Pablo Bezerra Vilar, Edson G. da Costa and Fabricio B. S. Carvalho

Energies 2024, 17(2), 392; https://doi.org/10.3390/en17020392 - 12 Jan 2024

Viewed by 543

Abstract

This paper introduces a novel approach for diagnosing failures within a turbogenerator mineral lube oil system, employing a fuzzy inference system (FIS) model. The study leverages real operational data collected from supervisory monitoring sensors across four turbogenerators over a three-year operational span, resulting [...] Read more.

This paper introduces a novel approach for diagnosing failures within a turbogenerator mineral lube oil system, employing a fuzzy inference system (FIS) model. The study leverages real operational data collected from supervisory monitoring sensors across four turbogenerators over a three-year operational span, resulting in a dataset comprising 40,456,663 input parameters. The failure modes were established through expert knowledge, using the Failure Mode, Effect, and Criticality Analysis (FMECA) documentation as the basis. Initially, the model’s universe variables were constructed using the sensor calibration range, and then the fuzzy membership functions were formulated based on the operational thresholds inherent to each measured parameter. The fault identification mechanism is underpinned by an inference system employing predefined rules, extrapolated from expert judgments encapsulating failure typologies specific to the turbogenerators’ mineral lube oil system, as delineated in the FMECA. The FIS model demonstrates notable efficacy in failure diagnosis with an overall performance evaluation of the system yielding satisfactory outcomes, having a 98.35% true positive rate for failure classification, coupled with a 99.99% true negative rate for accurate classification during normal system operation. These results highlight the visibility of the FIS model in diagnosing failures within the turbogenerator mineral lube oil system, thereby showcasing its potential for enhancing operational reliability and maintenance efficiency. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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19 pages, 5702 KiB

Open AccessArticle

Measuring and Modeling the Skin Effect for Harmonic Power Flow Studies

by Eduardo Tavares Silvério and Jose Rubens Macedo Junior

Energies 2023, 16(23), 7913; https://doi.org/10.3390/en16237913 - 04 Dec 2023

Viewed by 902

Abstract

This research aims to quantify the skin effect and estimate expressions that well represent the phenomenon for harmonic power flow studies. The primary focus is to validate the behavior of the skin effect at harmonic frequencies ranging from 60 Hz to 960 Hz, [...] Read more.

This research aims to quantify the skin effect and estimate expressions that well represent the phenomenon for harmonic power flow studies. The primary focus is to validate the behavior of the skin effect at harmonic frequencies ranging from 60 Hz to 960 Hz, while considering various amplitudes of electric current. The investigation not only examines the measurement of the skin effect, but also considers the temperature of the tested conductors, aiming to analyze the increase in resistance resulting from temperature rise and resistivity changes. The measurement outcomes demonstrate notable increments in electrical resistance, with resistivity increases of up to 1.9% observed throughout the measurement process. Finally, based on the results obtained through laboratory measurements, mathematical expressions were estimated as a function of frequency. In order to evaluate the simulation time reduction by the proposed expressions, OpenDSS (version: 9.4.1.2; Electric Power Research Institute, Knoxville, TN, USA) software was used, which aims at quantifying the impact of the skin effect on the technical losses. The results from these simulations demonstrate that the proposed expressions to account for the skin effect in conductors reduce the simulation time by around 17% for harmonic power flow. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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20 pages, 724 KiB

Open AccessArticle

Detection of False Data Injection Attacks in a Smart Grid Based on WLS and an Adaptive Interpolation Extended Kalman Filter

by Guoqing Zhang, Wengen Gao, Yunfei Li, Xinxin Guo, Pengfei Hu and Jiaming Zhu

Energies 2023, 16(20), 7203; https://doi.org/10.3390/en16207203 - 23 Oct 2023

Cited by 1 | Viewed by 838

Abstract

An accurate power state is the basis of the normal functioning of the smart grid. However, false data injection attacks (FDIAs) take advantage of the vulnerability in the bad data detection mechanism of the power system to manipulate the process of state estimation. [...] Read more.

An accurate power state is the basis of the normal functioning of the smart grid. However, false data injection attacks (FDIAs) take advantage of the vulnerability in the bad data detection mechanism of the power system to manipulate the process of state estimation. By attacking the measurements, then affecting the estimated state, FDIAs have become a serious hidden danger that affects the security and stable operation of the power system. To address the bad data detection vulnerability, in this paper, a false data attack detection method based on weighted least squares (WLS) and an adaptive interpolation extended Kalman filter (AIEKF) is proposed. On the basis of applying WLS and AIEKF, the Euclidean distance is used to calculate the deviation values of the two-state estimations to determine whether the current moment is subjected to a false data injection attack in the power system. Extensive experiments were conducted to simulate an IEEE-14-bus power system, showing that the adaptive interpolation extended Kalman filter can compensate for the deficiency in the bad data detection mechanism and successfully detect FDIAs. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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20 pages, 11782 KiB

Open AccessArticle

Real-Time Control of a Battery Energy Storage System Using a Reconfigurable Synchrophasor-Based Control System

by Prottay M. Adhikari, Luigi Vanfretti, Hao Chang and Koushik Kar

Energies 2023, 16(19), 6909; https://doi.org/10.3390/en16196909 - 30 Sep 2023

Cited by 1 | Viewed by 1173

Abstract

Synchrophasor-driven smart grid applications aiming to orchestrate a diverse set of Distributed Energy Resources (DERs) require extensive infrastructure including substantial instrumentation hardware, communication network extensions and controller installations for coordinated operation. This can make the overall installation expensive. Additionally, due to the computational [...] Read more.

Synchrophasor-driven smart grid applications aiming to orchestrate a diverse set of Distributed Energy Resources (DERs) require extensive infrastructure including substantial instrumentation hardware, communication network extensions and controller installations for coordinated operation. This can make the overall installation expensive. Additionally, due to the computational complexity and data-intensive nature of the PDC functionality, most of the existing PDC implementations are on a purely software level, making them unsuitable for the real-time applications. To address this, the current paper proposes an alternate architecture for the real-time synchrophasor-based control of DER applications (e.g., microgrids) incorporating a centralized synchronization hardware designed to replace aggregation Phasor Data Concentrators (PDCs) and supplementary control algorithms into a singular reconfigurable hardware. This particular hardware is termed a Synchrophasor Synchronization Gateway and Controller (SSGC). The robustness of the proposed architecture is tested by using real-time (RT) Controller Hardware-In-the-Loop (CHIL) simulation-based experiments by manipulating the communication network that connects the SSGC with multiple Phasor Measurement Unit (PMU) streams broadcasting data through the IEEE C37.118.2 protocol in real time. These PMU streams were generated by using a real-time microgrid model running on a Typhoon HIL 604 simulator. To manipulate the communication interface between the proposed SSGC hardware and the PMU streams, a configurable Wide Area Network (WAN) emulator and communication network impairment appliance deployed in the Candela Technologies CT910 external hardware was utilized. The real-time control system was expanded by incorporating a low-pass filter to eliminate the potential overswitching of a Battery Energy Storage System (BESS). The proposed architecture demonstrated a reliable performance under ideal to moderately tampered communication networks. However, under a significantly corrupted network, the performance of this architecture is acutely affected. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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17 pages, 2731 KiB

Open AccessArticle

Long-Term Voltage Stability Bifurcation Analysis and Control Considering OLTC Adjustment and Photovoltaic Power Station

by Sheng Li, Can Zhang and Jili Zuo

Energies 2023, 16(17), 6383; https://doi.org/10.3390/en16176383 - 03 Sep 2023

Cited by 2 | Viewed by 787

Abstract

The influence of photovoltaic (PV) output with stochasticity and uncertainty on the grid-connected system’s voltage stability is worth further exploration. The long-term voltage stability of a 3-bus system with a large-scale PV power station considering the adjustment of an on-load tap changer (OLTC) [...] Read more.

The influence of photovoltaic (PV) output with stochasticity and uncertainty on the grid-connected system’s voltage stability is worth further exploration. The long-term voltage stability of a 3-bus system with a large-scale PV power station considering the adjustment of an on-load tap changer (OLTC) was studied. In this typical system, two supercritical Hopf bifurcation (SHB) points are found using the bifurcation calculation. At the SHB point that appears first, a small sudden increase in reactive load power or a sudden increase in PV active power P_pv can eventually cause a voltage collapse after a long increasing oscillation. The long-term collapse phenomenon shows that SHB cannot be ignored in the PV grid-connected system. Meanwhile, the time constant of OLTC can affect the progress of long-term voltage collapse, but it has different effects under different disturbances. When P_pv drops suddenly at the SHB point, due to the adjustment of OLTC, the load bus voltage can recover to near the target value of OLTC after a long period of time. Similarly, the time constant of OLTC can affect the progress of long-term voltage recovery. To prevent the long-term voltage collapse when P_pv increases suddenly at the SHB point, a new locking-OLTC index I_lock, depending on the value of P_pv corresponding to the SHB point, and a locking OLTC method are proposed, and the voltage can be recovered to an acceptable stable value quickly. Compared with the system without OLTC, OLTC adjustment can effectively prevent long-term voltage oscillation instability and collapse, so that PV power can play a bigger role in power systems. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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18 pages, 6930 KiB

Open AccessArticle

Analysis of Secondary Controller on MTDC Link with Solar PV Integration for Inter-Area Power Oscillation Damping

by Oluwafemi Emmanuel Oni and Omowunmi Mary Longe

Energies 2023, 16(17), 6295; https://doi.org/10.3390/en16176295 - 29 Aug 2023

Viewed by 650

Abstract

Integration of renewable energy sources is important in limiting the continuous environmental degradation and emissions caused by energy generation from fossil fuels and thus becoming a better alternative for a large-scale power mix. However, an adequate analysis of the interaction with the alternating [...] Read more.

Integration of renewable energy sources is important in limiting the continuous environmental degradation and emissions caused by energy generation from fossil fuels and thus becoming a better alternative for a large-scale power mix. However, an adequate analysis of the interaction with the alternating current (AC) network during network disturbance, especially during inter-area power (IAP) oscillations is needed. Insufficient damping of oscillations can significantly impact the reliability and effective operation of a whole power system. Therefore, this paper focuses on the stability of the modified Kundur two-area four-machine (MKTAFM) system. A robust secondary controller is proposed and implemented on a line commutated converter (LCC)-based multi-terminal high voltage direct current (MTDC) system. The solution consists of a local generator controller and the LCC MTDC (LMTDC) system, voltage-dependent current order limiter, and extinction angle controller. The proposed robust controller is designed for the LMTDC systems to further dampen the inter-area power oscillations. Three operational scenarios were implemented in this study, which are the local generator controller and double circuits AC line, local generator controller with LMTDC controllers, and local generator controller with LMTDC controllers and secondary controller. The simulation result carried out on PSCAD/EMTDC recorded better damping of the inter-area power oscillation with LMTDC. A considerable improvement of 100% damping of the IAP oscillations was observed when a secondary controller was implemented on the LMTDC. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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13 pages, 2956 KiB

Open AccessArticle

Actions to Handle Increasing Distributed Generation and Rising Voltage during Low-Demand Periods: Tap Staggering Practices and Field Tests in the Italian Transmission Network

by Stefano Quaia, Alessandro Mauri, Alessio Marchesin and Paolo Manià

Energies 2023, 16(17), 6258; https://doi.org/10.3390/en16176258 - 28 Aug 2023

Viewed by 679

Abstract

This paper deals with the voltage regulation strategies implemented in the Italian transmission network to face the increasing problem of high voltages during time periods characterized by low demand. After an introduction in which this very actual problem is discussed, the focus is [...] Read more.

This paper deals with the voltage regulation strategies implemented in the Italian transmission network to face the increasing problem of high voltages during time periods characterized by low demand. After an introduction in which this very actual problem is discussed, the focus is on tap staggering practices. Although tap staggering is not a new idea, it is gaining practical importance only in the very last few years as a means of enhancing the inductive power drawn from the grid and, therefore, limiting the voltage rise. Accordingly, tap staggering contributes to the mitigation of the problems caused by the increasing penetration of renewable energy sources and thus can allow an increase in the share of renewable energy sources. The paper presents the different tap staggering practices that are being defined by the Italian transmission system operator and reports some tap staggering tests recently performed on large autotransformers as well as phase-shifter transformers. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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17 pages, 4315 KiB

Open AccessArticle

DC Admittance Model of VSCs for Stability Studies in VSC-HVDC Systems

by Joaquín Pedra, Luis Sainz and Lluís Monjo

Energies 2023, 16(14), 5457; https://doi.org/10.3390/en16145457 - 18 Jul 2023

Viewed by 735

Abstract

High-voltage direct current (HVDC) systems linked to AC grids with converters are promising energy transmission systems. These systems present complex AC- and DC-side dynamic interactions. Impedance-based stability studies have recently been proposed to assess DC-side dynamics from DC-side characterization of voltage source converters [...] Read more.

High-voltage direct current (HVDC) systems linked to AC grids with converters are promising energy transmission systems. These systems present complex AC- and DC-side dynamic interactions. Impedance-based stability studies have recently been proposed to assess DC-side dynamics from DC-side characterization of voltage source converters (VSCs) considering AC-side dynamics. However, the existing approaches used for stability studies in VSC-HVDC systems do not completely model VSCs because they do not consider together the VSC delay, the grid voltage feedforward filter, and all the d- and q-reference current controls. Moreover, these approaches are analytically characterized from dq-real space vectors (less related to circuit theory than dq-complex space vectors), and some work with simple AC grids. The main contribution of this paper is a detailed and complete DC admittance model of VSCs from dq-complex space vectors, which considers the VSC delay, feedforward filter, and d- and q-reference current controls, and also a general AC grid. The proposed model can be used for DC-side stability studies in VSC-HVDC systems considering AC grid dynamics. The capabilities and drawbacks of impedance-based stability methods for DC-side stability assessment were analyzed, and the positive-net-damping criterion was validated as a robust approach. The model was validated by PSCAD/EMTDC simulations and applied to a stability study in a VSC-HVDC system. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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17 pages, 9880 KiB

Open AccessArticle

Unique Symbolic Factorization for Fast Contingency Analysis Using Full Newton–Raphson Method

by Hakim Bennani, Ahmed Chebak and Abderrazak El Ouafi

Energies 2023, 16(11), 4279; https://doi.org/10.3390/en16114279 - 23 May 2023

Cited by 2 | Viewed by 887

Abstract

Contingency analysis plays an important role in assessing the static security of a network. Its purpose is to check whether a system can operate safely when some elements are out of service. In a real-time application, the computational time required to perform the [...] Read more.

Contingency analysis plays an important role in assessing the static security of a network. Its purpose is to check whether a system can operate safely when some elements are out of service. In a real-time application, the computational time required to perform the calculation is paramount for operators to take immediate actions to prevent cascading outages. Therefore, the numerical performance of the contingency analysis is the main focus of this current research. In power flow calculation, when solving the network equations with a sparse matrix solver, most of the time is spent factorizing the Jacobian matrix. In terms of computation time, the symbolic factorization is the costliest operation in the LU (Lower-upper) factorization process. This paper proposes a novel method to perform the calculation with only one symbolic factorization using a full Newton–Raphson-based generic formulation and modular approach (GFMA). The symbolic factorization retained can be used during the iterations of any power flow contingency scenario. A computer study demonstrates that reusing the same symbolic factorization greatly reduces computation time and improves numerical performance. Power system security assessment under N-1 and N-2 contingency conditions is performed for the IEEE standard 54-bus and 108-bus to evaluate the numerical performance of the proposed method. A comparison with the conventional power flow method shows that the time required for the analysis is shortened considerably, with a minimum gain of 228%. The comparative analysis demonstrates that the proposed solution has better numerical performance for large-scale networks. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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17 pages, 7580 KiB

Open AccessArticle

Overview of Various Voltage Control Technologies for Wind Turbines and AC/DC Connection Systems

by Yuan-Kang Wu, Deng-Yue Gau and Trinh-Duc Tung

Energies 2023, 16(10), 4128; https://doi.org/10.3390/en16104128 - 16 May 2023

Cited by 2 | Viewed by 1595

Abstract

Wind power generation is one of the mainstream renewable energy resources. Voltage stability is as important as the frequency stability of a power system with a high penetration of wind power generation. The advantages of high-voltage direct current (HVDC) transmission systems become more [...] Read more.

Wind power generation is one of the mainstream renewable energy resources. Voltage stability is as important as the frequency stability of a power system with a high penetration of wind power generation. The advantages of high-voltage direct current (HVDC) transmission systems become more significant with the increase of both installed capacity and transmission distance in offshore wind farms. Therefore, this study discusses various voltage control methods for wind turbines and HVDC transmission systems. First, various voltage control methods of a wind farm were introduced, and they include QV control and voltage droop control. The reactive power of a wind turbine varies with active power, while the active power from each wind turbine may be different owing to wake effects. Thus, QV and voltage droop control with varying gain values are also discussed in this paper. Next, the voltage control methods for an HVDC transmission system, such as power factor control, voltage control, and V_ac-Q control, are also summarized and tested in this study. When a three-phase short circuit fault occurs or a sudden reactive power load increases, the system voltage would drop immediately. Thus, various voltage control methods for wind turbines or HVDC can make the system’s transient response more stable. Therefore, this study implemented the simulation scenarios, including a three-phase short circuit fault at the point of common coupling (PCC) or a sudden increase of reactive power load, and adopted various voltage control methods, which aim to verify whether additional voltage control methods are effective to improve the performance of transient voltage. The voltage control method has been implemented in PSCAD/EMTDC, and the simulation results show that the QV control performs better than the droop control. In addition, when applying the voltage control technique during a three-phase fault, transient voltage nadir can be improved through either an HVDC transmission system or an AC transmission system. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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Review

Jump to: Research

45 pages, 3058 KiB

Open AccessReview

A Comprehensive Review on the Modelling and Significance of Stability Indices in Power System Instability Problems

by Chandu Valuva, Subramani Chinnamuthu, Tahir Khurshaid and Ki-Chai Kim

Energies 2023, 16(18), 6718; https://doi.org/10.3390/en16186718 - 20 Sep 2023

Cited by 1 | Viewed by 1261

Abstract

Many technological advancements in the modern era have made actual use of electrical power and the constrained operating of power systems within stability limits. Some expeditious load variations and rising power demands initiate complications in voltage stability and can put stress on performance, [...] Read more.

Many technological advancements in the modern era have made actual use of electrical power and the constrained operating of power systems within stability limits. Some expeditious load variations and rising power demands initiate complications in voltage stability and can put stress on performance, leading to voltage instability. Voltage Stability Indices can be used to perform voltage stability assessment. This review evaluates various VSIs based on mathematical derivations, assumptions, critical values, and methodology. VSIs determine the maximum loadability, voltage collapse proximity, stability margin, weak areas, and contingency ranking. Stability indices can also specify the optimal placing and sizing of Distributed Generators. Thus, VSIs play a vital role in power system voltage stability. This review is a comprehensive survey of various indices and analyses their accuracy in determining the instability of power systems. Voltage stability is a crucial concern in operating a reliable power system, and the systematic evaluation of voltage stability is essential in a power system. This review considered and analyzed 34 indices from 138 articles from the literature for their significant performance in various power system stability problems. Of 33 indices, were 22 derived from transmission line parameters, referred to as line indices, and 12 from bus and line parameters, referred to as bus indices. Full article

(This article belongs to the Special Issue Advanced Electric Power System 2023)

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