Transient Stability Control Research Articles

Transient Stability Control Strategy Based on Uncertainty Quantification for Disturbances in Hybrid Energy Storage Microgrids

Transient Stability Control Strategy Based on Uncertainty Quantification for Disturbances in Hybrid Energy Storage Microgrids

Coordinated FRT Control for Paralleled Grid- Forming Converters With Enhanced Transient Stability and Current Control Flexibility

Coordinated FRT Control for Paralleled Grid- Forming Converters With Enhanced Transient Stability and Current Control Flexibility

Modular Open Source Solar Photovoltaic-Powered DC Nanogrids with Efficient Energy Management System

Initially the concept of a DC nanogrid was focused on supplying power to individual homes. Techno-economic advances in photovoltaic (PV) technology have enabled solar PV stand-alone nanogrids to power individual devices using device-specific architectures. To reduce costs and increase accessibility for a wider range of people, a modular open-source system is needed to cover all applications at once. This article introduces a modular PV-powered nanogrid system, consisting of a do it yourself (DIY) PV system with batteries to allow for off-grid power. The resultant open-source modular DC nanogrid can deliver DC power to loads of different voltage levels, which is possible because of the efficient and parametric energy management system (EMS) that selects modes of operation for the grid based on DC bus voltage and state of charge of batteries. Simulation results verify the coordination between the EMS and the PV-battery system under varying PV power generation and load conditions. This EMS has potential to enable easy personalization of a vast area of applications and expand appropriate technology for isolated communities. A thorough stability analysis has been conducted, leading to the development of an LQR (Linear Quadratic Regulator) controller as a replacement for the conventional PI (Proportional - Integral) controllers for better transient stability of the system.

Transient Interaction Mechanism Analysis and Stability Control of Multi-paralleled DFIG-Based WTs during Asymmetrical Grid Faults

Transient Interaction Mechanism Analysis and Stability Control of Multi-paralleled DFIG-Based WTs during Asymmetrical Grid Faults

Distributed Fixed-Time Transient Stability Control Scheme for Power Systems With Heterogeneous Dynamics

Distributed Fixed-Time Transient Stability Control Scheme for Power Systems With Heterogeneous Dynamics

A combined regulation method of transient power angle stability control and fault current suppression for VSG

When a serious grid fault occurs, a virtual synchronous generator (VSG) tends to lose transient power angle stability (TPAS) and cause the fault current to exceed the limit. Most existing research usually neglects the inherent relationship between transient power angle instability (TPAI) and fault over-current (FOC), which leads to the two problems being solved separately rather than simultaneously. In this paper, the transient power angle and fault current characteristics of VSG are first studied, and the causes and influencing factors of TPAI and FOC are explored. Then, the TPAS analysis is carried out based on the phase portrait theory. A TPAS control method for VSG considering fault current suppression (FCS) is proposed. This method is fulfilled by the combined regulation of active power reference and reactive voltage regulation coefficient, in which the reference and coefficient can be adjusted adaptively according to different fault degrees and application scenarios. In addition, a quasi-static approximate (QSA)virtual inductance is introduced to limit the instantaneous inrush current (IIC). The proposed method achieves both the TPAS and FCS at the same time during the fault. Finally, simulations and experiments verify the correctness of the theoretical analysis and the proposed method.

A Novel Data-Driven Self-Tuning SVC Additional Fractional-Order Sliding Mode Controller for Transient Voltage Stability With Wind Generations

This paper proposes a novel data-driven self-tuning additional sliding mode controller for power system transient voltage stability enhancement considering wind integration. We first develop a new additional fractional-order sliding mode controller (FOSMC) for the static var compensator (SVC). The tuning of FOSMC parameter settings is then reformulated as a Markov decision process (MDP) and solved by the deep reinforcement learning (DRL) algorithm. In addition, a data-driven estimation method is proposed for the identification of an equivalent transfer function that is further used to calculate reward during the training process, yielding the model-free training. After that, the well-trained agent allows us to tune the controller parameters considering system uncertainties and achieve robustness against various operating conditions. Comparative results with other state-of-art methods demonstrate that the proposed method can effectively suppress the chattering issue of the sliding mode controller and ensure transient voltage stability under different operating conditions.

A Novel Transient Stability Control Strategy for an AC/MTDC Grid Under $N-k$ Contingency Induced by Typhoon Extreme Weather

Due to the severe global warming, the frequency and intensity of typhoon extreme weather events have increased around the world. These events would cause serious <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N-k$</tex-math></inline-formula> contingency of coastal AC/multi-terminal high voltage DC (MTDC) power grid, resulting in a high possibility of transient instability. To address this problem, this paper develops a novel two-stage resilient control strategy. In the first stage, an optimization model is established to obtain a control scheme that involves generator rescheduling, load shedding and MMC operation point adjustment after <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N-k$</tex-math></inline-formula> contingency. In the second stage, an active power modulation method of modular multi-level converters (MMC) based on the model predictive control algorithm is proposed to improve the transient stability of the coastal AC/MTDC grid. The proposed control strategy makes full use of the flexible control resources of MMC-MTDC, thereby increasing the transient stability margin of the coastal AC/MTDC grid. The effectiveness of the proposed strategy has been validated on an AC/MTDC power grid built on MATMTDC that is an open source software based on MATLAB. Simulation results demonstrate that the proposed two-stage resilience control strategy exhibits promising performance in enhancing the transient stability of the coastal AC/MTDC power system when suffering a typhoon event.

Power system transient stability preventive control optimization method driven by Stacking Ensemble Learning

The dynamic characteristics of the power system are becoming more and more complex, and the difficulty of operation control is increasing. Preventive control is the main means of power system transient stability control. This paper proposes a stacking ensemble learning-driven power system transient stability preventive control optimization method. Firstly, a transient stability assessment model based on Stacking Ensemble Deep Belief Nets (SEDBN) network is established in this research. The performance of weak classifiers is improved by SEDBN’s multi-layer ensemble structure, and the created transient stability estimator can extract diverse features and has better robustness and generalization abilities. Secondly, the trained transient stability estimator is integrated into the Aptenodytes Forsteri Optimization (AFO) algorithm as a “transient stability constraint discriminator”. Finally, with the goal of minimizing the cost of preventive control, an optimization algorithm for the preventive control of power system transient stability driven by SEDBN is established. Simulation results on IEEE 39-bus systems show that the proposed method can achieve highly efficient control solutions.

Enhanced transient angle stability control of isolated power grid based on phase sequence exchange

An isolated power grid (IPG) lacks the support of the external power grid, and a single generator or load accounts for a large proportion of the total capacity. Once transient angle instability, the generator and load shedding is not effectively. Phase sequence exchange (PSE) uses power electronic devices to switch the three-phase sequence, thereby reducing the power angle of the generator by 120° and preventing the system from losing stability. This paper proposed a PSE scheme for transient angle instability applied to IPG. The local measurements of IPG are used to identify the critical generator, and the system trajectory is obtained through large-step integration. The stability is assessed by the concavity of the trajectory. Once the trajectory swings from the concave area to the convex area, the IPG loses transient stability, at which point the generators in the critical cluster simultaneously PSE prevent transient instability. Based on Simulink and RTDS platform, the scheme is verified in a 39-bus 10-machine system and an existing IPG system. The results show that the proposed scheme can effectively restore the stability of the IPG, outperforming generators and load shedding.

Robustly Cooperative Control of Transient Stability for Power System Considering Wind Power and Load Uncertainty by Distribution Preserving Graph Representation Learning (DPG)

Aiming at the influence of wind power and load uncertainty on the transient stability of a power system under low carbon mode, this paper first proposes a collaborative preventive and emergency control model of transient stability by distribution preserving graph representation learning (DPG). Second, the uncertainty set of wind power output and load demand is studied, and the mathematical form of the two-stage robust transient stability collaborative control model is proposed. Then, the latest artificial intelligence technology is embedded into the global optimization algorithm of the model so as to further improve the solving efficiency of the algorithm. Finally, based on the developed improved two-stage robust optimization framework, an effective collaborative control method for transient stability is developed. The transient stability prediction and control system developed in this project is not only conducive to large-scale wind power grid connection but also expected to make academic contributions to development of power system transient stability and practical simulation verification.

Online prediction and control of post-fault transient stability based on PMU measurements and multi-task learning

The combined usage of phasor measurement units and machine learning algorithms provides the opportunity for developing response-based wide-area system integrity protection scheme against transient instability in power systems. However, only the transient stability status is usually predicted in the literature, which is not enough for real-time decision-making for response-based emergency control. In this paper, an integrated approach is proposed. The GRU-based predictor is firstly proposed for post-disturbance transient stability prediction. On this basis, a multi-task learning framework is proposed for the identification of unstable machines and also the estimation of generation shedding. Case study on the IEEE 39-bus system demonstrates that, apart from the basic task of transient stability prediction, the proposed GRU-based multi-task predictor can predict the grouping of unstable machines correctly. Moreover, based on the estimated amount of generation shedding, the generated remedial control actions can retain the synchronism of the power system.

AI-oriented Smart Power System Transient Stability: The Rationality, Applications, Challenges and Future Opportunities

Nowadays, the power grid has become an active colossal resource generation and management system due to the wide use of renewable energy and dynamic workloads processed through intelligent information and communication technologies. Several new operations exist, such as power electrification, intelligent information integration on the physical layer, and complex interconnections in the smart grid. These procedures use data-driven deep learning, big data, and machine learning paradigms to efficiently analyze and control electric power system transient problems and resolve technical issues with robust accuracy and timeliness. Thus, artificial intelligence (AI) has become vital to address and resolving issues related to transient stability assessment (TSA) and control generation. In this paper, we provide a comprehensive review on the role of AI and its sub-procedures in addressing problems in TSA. The workflow of the article includes an AI-based intelligent power system structure along with power system TSA and AI-application rationality to transient situations. Outperforms other reviews, this paper discusses the AI-based TSA framework and design process along with intelligent applications and their analytics in power system transient problems. Moreover, we are not limited to AI, but we also combine the direction of big data that is highly compatible with AI, discusses future trends, opportunities, challenges, and open issues of AI-Big data based transient stability assessment in the smart power grid.

Enhanced Transient Angle Stability Control of Grid-Forming Converter Based on Virtual Synchronous Generator

Attributed to the ability of inertia provision and good regulation performance, the virtual synchronous generator (VSG) has been proven as a promising solution to the problems introduced by using converter interfaced generation. Although the small-signal stability control of the VSG has been widely analyzed, the transient characteristics still needs more study, which belongs to a large-signal problem. In this article, the transient angle stability control of the VSG is investigated. Two possible VSG emulation methods, i.e., the power-emulation and the torque-emulation, are compared from the perspective of transient characteristics. Then, the transient of the VSG internal voltage and its impact on the transient angle stability are quantitatively studied in details. Thereafter, an enhanced VSG controller is proposed, where a large-signal analysis is also presented to evaluate its influence on the acceleration and deceleration areas. Finally, the analysis and effectiveness of the enhanced VSG method are validated by the experimental results.

Battery storage to improve the cutter negative effect transient stability control strategy

To improve the transient stability of power grid, this paper proposes an emergency control strategy considering battery storage to participate in the transient stability of power grid. The phase plane trajectory convexity is used to identify the transient stability of the power grid. After the system is unstable, the dual-machine equivalence is carried out for the multi-machine power system regulated by the energy storage power supply, and the control quantity required by the energy storage power supply to restore the system stability in the single-machine system is calculated. The effectiveness of the control strategy was verified in the EPRI-7 system. The simulation results show that the transient stability emergency control strategy with energy storage power participating in the regulation can effectively improve the transient stability, reduce the emergency control failure, and inhibit the frequency and voltage reduction.

Transient Stability Evaluation Criterion of Multi-Wind Farms Integrated Power System

This letter proposes a novel transient stability criterion for power systems with multi-wind farms, which is deduced from power flow and inertia distribution. The variations of acceleration and deceleration power with and without wind integration, instead of the acceleration and deceleration areas themselves, are calculated, in which the power angle swing direction, the transient stability control of wind turbines, the position of wind farms access, and the unbalanced output of synchronous clusters are also considered. The simulation results show the effectiveness of the proposed criterion to distinguish transient stability.

Study on power grid transient stability control assisted by large-scale energy storage

With the development of energy storage technology, energy storage power station has gradually become one of the main means to solve the voltage instability of the main network caused by uHV DC bipolar phase lock. Therefore, energy storage model has become a difficulty in research. Firstly, the structure model of power storage station participating in power grid voltage transient stability control system is constructed, and the control strategy of power storage station is analyzed. Secondly, in the power system analysis software package (PSASP), the ES model of transient voltage stability control is established by using user-defined modules, and each module in the model is introduced in detail, so as to realize the purpose of enhancing voltage transient stability control of energy storage power station connected to the power grid. Finally, the simulation results show that compared with the adjustable camera, the voltage recovery speed is faster when the same capacity ES is connected in the same place. For example, the voltage recovery speed of 110kV bus decreases from 2.42s to 1.69s, and the recovery speed is increased by 30.17%. And PCS of ES power station has enough short time (<1s) overload capacity, then the ES configuration capacity can be less than the camera capacity.

Transient Synchronization Stability Improvement Control Strategy for Grid-Connected VSC Under Symmetrical Grid Fault

Under grid fault, the grid-connected voltage source converters (VSCs) have the risk of transient synchronization instability during low voltage ride through. Based on the equivalent rotor swing equation of VSC, this letter proposes an improved transient synchronization stability control strategy, which improves the existence of equilibrium points and transient synchronization behaviors of the VSC system. Thus, the transient synchronization stability of grid-connected VSC can be significantly enhanced. The simulation and experimental results demonstrate the validity of the proposed strategy.

Transient Stability Analysis and Control of Distributed Photovoltaic Generators in the DC Distribution Network

As dominant power sources, the safe and reliable operation of photovoltaic (PV) generators is crucial for the DC distribution network. This study analyzes the transient stability of PV generators under large disturbances and proposes a variable parameter control strategy to suppress the transient instability. First, the transient stability of the PV generators is analyzed using the proposed power–voltage evolution curve. It is found that the PV side easily suffers undervoltage faults during the transient process, which will cause instability of the system. Based on the revealed unstable mechanism, the variable parameter control is proposed to enhance the transient stability of PV generators. Finally, all the findings have been validated by hardware-in-loop tests.

Neural Lyapunov Control for Power System Transient Stability: A Deep Learning-Based Approach

Power system control and transient stability analysis play essential roles in secure system operation. Control of power systems typically involves highly nonlinear and complex dynamics. Most of the existing works address such problems with additional assumptions in system dynamics, leading to a requirement for a complete and general solution. This paper, therefore, proposes a novel control framework for various power system control and stability problems leveraging a learning-based approach. The proposed framework includes a two-module structure that iteratively and jointly learns the candidate Lyapunov function and control law via deep neural networks in a learning module. Meanwhile, it guides the learning procedure towards valid results satisfying Lyapunov conditions in a falsification module. The introduced termination criteria ensure provable system stability. This control framework is verified through several studies handling different types of power system control problems. The results show that the proposed framework is generalizable and can simplify the control design for complex power systems with the stability guarantee and enlarged region of attraction.