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Enhanced robust frequency stabilization of a microgrid against simultaneous cyber-attacks
(2024-03-01)
Kerdphol, Thongchart
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Ngamroo, Issarachai
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Surinkaew, Tossaporn
A microgrid (MG) is a smart grid cyber-physical system, with component coordination relying on cyber resilience. Weak communications, protocols, and tools make the MG's secondary frequency control vulnerable to various cyber-attacks, posing new challenges and stability risks. In response to this challenge, this paper introduces the enhanced robust H<inf>∞</inf> technique considering the dynamic impacts of cyber-attacks on secondary frequency control to develop a secondary frequency control loop, improving the regulation performance and cyber resiliency of the MG frequency. The secondary control cyber-attack strategies mainly rely on false data injection (FDI), denial of service (DoS), and controller hijacking. These attack techniques are simultaneously considered in formulating the H∞ problem and control synthesis as unstructured parametric uncertainty, attenuating the concurrent cyber impacts. The study extends a load frequency control model to illustrate how cyber-attacks can be represented mathematically and physically in the MG. The results reveal that cyber-attacks affect secondary frequency control elements differently depending on the type of cyber threats used. By implementing an enhanced H∞ controller, the MG can effectively maintain stable frequency levels even when faced with malicious attacks and disruptions caused by renewable energy sources and loads.
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Cyber-Attacks on Power System Frequency Control
(2024-01-01)
Kerdphol, Thongchart
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Teera-Achariyakul, Noppada
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Surinkaew, Tossaporn
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Pinthurat, Watcharakorn
Due to the increasing number of cyber hacking activities, cyber-Attacks become urgent concerns to power system security worldwide. A power system is vulnerable to cyber-Attacks due to the exchanged information in its area. In this study, cyber-Attacks on power system frequency control are studied by corrupting the exchange of information. Considering the frequency measurement of the system, essential attack strategies from hackers' perspectives, which are usually concerned with cyber-Attacks on critical infrastructure, have been modeled concerning the false data injection. Simulation results analyze the strengths and weaknesses of different attacks against frequency control of the system. The exogenous cyber-Attacks on frequency power measurements can cause severe frequency excursions, which lead to system instability and power blackouts. Such attack methods require effective detection from defenders to guarantee system security before hackers further deteriorate the system's stability.
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Small-Signal Stability Analysis in an Uncertain Microgrid with Distributed Energy Resources: A Data-Driven Monitoring
(2024-01-01)
Pinthurat, Watcharakorn
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Surinkaew, Tossaporn
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Kerdphol, Thongchart
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Marungsri, Boonruang
In low-inertia microgrids (MGs) with intermittent distributed energy resources (DERs), the requirement to pre-determine MG parameters results in a challenge as these parameters evolve over time. Consequently, conducting small-signal stability analysis becomes impractical due to the dynamic nature of the MG's parameter variations. In this paper, we propose an adaptive data-driven approach designed for grid-forming converters of DERs. The goal is to improve small-signal stability within a dynamically shifting window range. Additionally, we propose a data-driven approach to identify the MG model within a moving window. Subsequently, small-signal stability can be assessed. Comprehensive simulation results are systematically generated for an MG with DERs under various crucial conditions, including (i) intermittent power outputs of DERs, (ii) generator outages, (iii) diverse levels of total MG inertia, and (iv) different MG operation modes.
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Informatics-Centric Neural Network for Distributed Energy Resources Against Diverse Cyber Threats
(2024-01-01)
Surinkaew, Tossaporn
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Kerdphol, Thongchart
This article addresses challenges in modernizing microgrids (MGs) with distributed energy resources (DERs), which emphasizes cybersecurity vulnerabilities causing from integrating high DERs with cyber-physical data. To ensure seamless integration of DERs and to achieve optimal control performance, this article introduces an informatics-centric neural network (named I-ANN), which is specifically designed for DERs in weak MGs to encounter cyber threats, such as communication latency, false data injection, denial of service, and controller hijacking. The proposed framework utilizes multiagent systems to model the risks posed by cyber threats, with a particular emphasis on their impacts on frequency and voltage regulations. Here, the proposed I-ANN features a novel loss function for automatic signal restoration, and the I-ANN is iteratively trained using various cyber threat scenarios. During critical MG operating scenarios, the new loss function is proposed to enhance robustness and damping while simultaneously mitigating rapid fluctuations in voltage and frequency. Moreover, a significant departure from typical voltage and frequency control loops is the complete replacement of conventional PI controllers with the proposed I-ANN. This strategy fortifies resilience without requiring any additional controllers or control loops. Comparative analyses demonstrate I-ANN's effectiveness in low-inertia MGs with DERs through probabilistic small-signal stability analysis and time-domain simulations under diverse operating conditions.
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Dynamic Assessment of Thailand's Available Transfer Capability for Third-Party Access
(2024-01-01)
Khakkharho, Dhamrongsak
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Sutheerawut, Thanakorn
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Sanjaisue, Junlachat
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Kerdphol, Thongchart
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Teera-Achariyakul, Noppada
Thailand is experiencing significant growth in renewable energy sources, such as solar power and wind power. This growth is leading to an increase in independent electricity trading across public, private, and household sectors, making Thailand the origin of third-party access to electricity in the country. However, the current transmission infrastructure is struggling to keep pace with this development, making it challenging to assess regional transmission capabilities accurately. Furthermore, the rapid urban and industrial growth has also resulted in a significant increase in electricity demand, emphasizing the urgent need for a robust transmission and distribution network. To address these challenges, a paper is currently underway to model the remaining transmission capacity in Thailand's regions using real data and sophisticated electrical engineering software. This analysis primarily concentrates on Available Transfer Capability known as ATC, which draws insights from various methods used in the Indian case study. The goal is to enhance the utilization of the transmission system, support independent electricity trading, and guarantee the stability, security, and reliability of the power system in line with the changing electricity market.
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Synthetic Inertia-Power Sharing in High Renewable Power Grids Through Vehicle-to-Grid Topology
(2024-01-01)
Kerdphol, Thongchart
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Surinkaew, Tossaporn
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Ngamroo, Issarachai
With the increasing integration of renewable energy sources (RESs), the overall inertia of the power system is expected to decline. The remaining inertia is crucial for regulating system frequency and mitigating excessive rates of change. The deployment of dispatchable loads, such as electric vehicles (EVs), offers a promising solution. This paper presents a synchronized inertia support framework utilizing a vehicle-to-grid (V2G) system through its bidirectional chargers. This concept is realized by integrating a large-scale energy storage system (ESS) composed of controllable EVs into an enhanced inertia emulation structure. The synthetic inertia control strategy has been refined to account for EV user convenience and synchronized state of charge (SOC) management, facilitating synchronized inertia power sharing. This approach enhances the grid's dynamic performance and resilience. Simulation results demonstrate that the proposed method effectively delivers rapid inertia support from the onboard ESS of EVs, improving frequency stability.
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Forced oscillation suppression using extended virtual synchronous generator in a low-Inertia microgrid
(2023-09-01)
Kerdphol, Thongchart
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Ngamroo, Issarachai
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Surinkaew, Tossaporn
Effects of forced oscillations (FOs) in well-damped power systems are relatively smaller than those of microgrids (MGs) in which the severity of the FOs may be intensified by converter interfaced generators (CIGs). According to the distinct system characteristics, the FOs in MGs will be challenging problems in future research topics. Without proper controls of the CIGs, the FOs may be exhibited extremely higher amplitude, resulting in the MG instability. Such influences will be exacerbated in a low-inertia MG, which can trigger critical frequency oscillation and system collapse. This paper introduces an extended virtual synchronous generator (VSG) with virtual forced components to attenuate the dynamic FO effects in the presence of a low-inertia MG. Contrastive scenarios, i.e., periodic, combined, full sine, and high-frequency FOs are conducted to validate the performances of VSG control in both stand-alone and interconnected MG environments. Numerical results verify that the extended VSG control provides promising benefits in a low-inertia MG not only for the sake of MG stability improvement but also the further FO suppression.
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Evaluating Regional Inertia-based COI with Synchrophasor Measurement
(2023-01-01)
Kerdphol, Thongchart
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Tephiruk, Naowarat
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Surinkaew, Tossaporn
Due to the replaced number of large synchronous generators and renewable penetration, the center of inertia (COI) becomes a key factor in wide-area control with stability analysis. Knowing the area-based COI frequency significantly introduces the inertia estimation latency regarding periodic time-varying. This work proposes a pseudo technique based on measured angles of phasor measurement units (PMUs) to determine the area-based COI frequency, thus improving the precision of inertia estimation of the real-world power system. At the beginning, a two-machine model strategy is presented by considering ambient signals from potential PMU locations/buses while dividing the area estimation into a separate quantity of two significant areas (i.e., western and eastern regions) regarding the longitudinal 60 Hz Japan transmission network. Then, the pseudo phasor observation points considering different locations in both areas are established to determine the COI frequency for each area. The resulting accuracy is verified by comparing to the ratio of known/contributing synchronous power outputs. Finally, the estimated inertia-based COI frequencies in both areas are combined to identify the total system inertia in comparison with the conventional inertia estimation-based disturbance technique.
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Inertia Assessment From Transient Measurements: Recent Perspective From Japanese WAMS
(2022-01-01)
Kerdphol, Thongchart
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Watanabe, Masayuki
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Mitani, Yasunori
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Ngamroo, Issarachai
Currently, the substantial renewable penetration brings a low inertia issue to the Japanese power system, threatening stability and resiliency than ever. The inertia estimation based on transient events provides a reliable basis for system control and operation. However, the poor rate of change of frequency extraction from different types and locations of phasor measurement units (PMUs) could significantly lead to inertia estimation errors. As a remedy with a lesson learned, this paper analyzes effective inertia estimations based on transient measurements of the Japanese wide-area monitoring in both distribution and transmission levels. Due to the longitudinally interconnected configuration of the 60 Hz Japanese power system, the polynomial approximation technique is proposed to restrain the strong effect of oscillatory components. To enhance the estimation performance considering an existing center of inertia, the comprehensive mode-shape analysis is performed via geographical measurement locations, indicating sufficient PMUs with precise estimation. The effectiveness of inertia estimation techniques is verified through actual system events corresponding to various transient sites. The numerical results demonstrate that recent inertia of the 60 Hz Japanese system with existing renewables ranges around 7.12 - 8.13 s in its system load base.
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Small-signal analysis of multiple virtual synchronous machines to enhance frequency stability of grid-connected high renewables
(2021-04-01)
Kerdphol, Thongchart
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Rahman, Fathin Saifur
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Watanabe, Masayuki
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Mitani, Yasunori
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Hongesombut, Komsan
The virtual synchronous machine technology is considered as an important technique to effectively control the shortcomings of renewable energy-based power electronics interfaces, providing backup inertia and regulating grid stability. Conventionally, the virtual synchronous machine with a large capacity is responsible for controlling the entire grid stability against renewable penetration. It is usually operated as a centralised control system. But what if virtual synchronous machines with small capacities are independently operated by their additional droop control schemes, and will they present better performance than the single virtual synchronous machine? This study proposes the multiple virtual synchronous machine system with different active power-frequency (P-f) droop characteristics to improve inertia support regarding frequency stability improvement. The comprehensive small-signal modelling of the multiple virtual synchronous machine unit is designed to include the additional P-f droop characteristics. Then, the dynamic characteristics (steady-state and transient responses) and static stability of the multiple virtual synchronous machines are compared with the single virtual synchronous machine at the same rated capacity in both eigenvalue/sensitivity-domain and time-domain analysis. The obtained results reveal that the system with the presence of several virtual synchronous machines is more stable than the system with single virtual synchronous machine, maintaining stable and secure system operation during the contingency.

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