Power System Angle Stability Research Articles

Advanced UPFC Controllers to Improve Transient and Dynamic Stabilty of Power System

The industrial revolution is thought to have had its foundation in electricity. Electricity must be produced and transferred in greater quantities in order to meet the ever rising demand that must be delivered to numerous homes and businesses. it is slightly challenging to do so in a very flexible and efficient manner. So for transmission of such a large amount of electricity, In terms of the examination of the power system, (FACTS) will have been discovered to be a potential component. The comparative analysis of UPFC in the presence LG fault is described in this paper. Fuzzy logic controller has better performance in improving transient stability than conventional PI controller. System consist of multimachine power system with fault is simulated in MATLAB environment the results are also tested using prototype hardware model of set up 01 KVAR UPFC. There is improvement in rotor angle stability of power system using Fuzzy logic controller compared to conventional PI controller. Oscillations are also reduce with this FUZZY based UPFC controller

Intelligent method for Power flow using Artificial Neural Network with UPFC

It is slightly difficult to transmit such a large amount of electricity in very flexible and efficient way as the size of conventionally used relay and protective devices will increase while transmitting such a large amount of electricity which will increase the operating cost. So for transmission of such a large amount of electricity, Flexible Alternating Current Transmission Systems (FACTS) will have been found to be promising aspect in terms of the analysis of the power system. In this paper the comparative analysis of unified power flow controller(upfc) is presented in presence of LG fault. ANN controllers are applied in UPFC in MATLAB/SIMULINK environment. There is significant reductions in oscillations in rotor angle deviation of multimachine systems using ANN controller compare to conventional PI controller. Hardware prototype model of UPFC also shows improvement in voltage stably in multimachine. There is improvement in rotor angle stability of power system using ANN controller compared to conventional PI controller. Oscillations are reduced.

Analysis of power system angle stability based on Heun algorithm under gauss and jump excitation

In the process of promoting the dual-carbon goals, the “double-high” character of the power system is gradually becoming obvious and brings a lot of random factors, such as high proportion of new energy access and cut out power system, brings gauss excitation from continuous fluctuations and jump excitation from shock fluctuations, affecting the power system safety operation. Combining the effects of gauss excitation and jump excitation, described as excitation terms acting on gauss white noise and poisson white noise. Constructing the stochastic dynamic model with jump of power system, Heun method is constructed to solve the model, and the comprehensive influence of stochastic excitation and jump excitation under different intensities on stability analysis is analyzed quantitatively. The simulation results of one-machine infinite-bus (OMIB) system shows the correctness and rationality of the method constructed, and provides ideas for the analysis of power system stability under the combined influence of multiple types of random factors.

Phase Sequence Exchange Technology Based on MMC for Improving the Power Angle Stability of Power Systems

Power angle stability of power systems is one of the main factors which restricts the power transmission capacity. In order to prevent the power angle instability of power systems, phase sequence exchange (PSE) is a recently developed emergency control technique that reduces the power angle by 120°. This paper proposes a new phase sequence exchange technology based on a modular multi-level converter (MMC). In this paper, the concept of deceleration area ratio is proposed, that is used to characterize the power angle stability of the power system, and the phase sequence exchange theory based on an MMC is analyzed. A phase sequence exchange circuit based on a modular multilevel converter (MMC) is designed. In this paper, the system parameters of the MMC-based PSE are optimized. Finally, a model is developed on PSCAD. The simulation results show that the MMC-based phase sequence exchange technology can effectively improve the power angle stability of the power system.

Performance of Controller Designs in Small-Disturbance Angle Stability of Power Systems with Parametric Uncertainties

The electric power system is a complicated dynamic system with a range of operating states and parametric uncertainties, especially due to change of the network topology, load increment and generation scheduling. Under this circumstance, traditional power system transient stability analysis methods may not always be appropriate. This paper presents the development of a computational methodology for evaluating the effect of parametric uncertainties on the small-signal stability analysis of power systems. A probabilistic approach is applied as a metric for the dynamic performance of the damping ratio of critical eigenvalues. The method is based on a Monte Carlo simulation for the analysis of automatic control of generation. The methodology is used for the performance evaluation of three classical controller tuning techniques: Frequency Response, Approximate Method and Ziegler-Nichols. The results show that the methodology is valid and potentially useful for quantifying the effect of parametric uncertainties in power systems dynamics simulations.

Enhancing rotor angle stability of power systems using marine predator algorithm based cascaded PID control

In this paper, the cascaded control scheme is introduced for the first time to the rotor stability problem. Cascaded excitation and governing control schemes are introduced to damp rotor oscillations. PID cascaded control is used for its popularity and effectiveness. These controllers will be fine-tuned using a novel metaheuristic optimization technique, namely the Marine Predator Algorithm; which mimics the movement of marine predators when foraging. This technique is popular for always converging to a constant stable point. Our study will be performed on two systems, the simple single machine to infinite bus power system and the popular IEEE-39 bus system to study both local and global oscillations, respectively. Results show the effectiveness of the new proposed cascaded control scheme compared to the conventional scheme in improving the damping of the rotor oscillations without the need of a power system stabilizer. Results are provided as time domain simulation via MATLAB/SIMULINK.

Rotor Angle Stability Prediction of Power Systems With High Wind Power Penetration Using a Stability Index Vector

This paper proposes a methodology for predicting online rotor angle stability in power system operation under significant contribution from wind generation. First, a novel algorithm is developed to extract a stability index ( SI ) that quantifies the margin of rotor angle stability of power systems reflecting the dynamics of wind power. An approach is proposed that takes advantage of the machine learning technique and the newly defined SI . In case of a contingency, the developed algorithm is employed in parallel to find SI s for all possible instability modes. The SI s are formed as a vector and then applied to a classifier algorithm for rotor angle stability prediction. Compared to other features used in state-of-the-art methods, SI vectors are highly recognizable and thus can lead to a more accurate and reliable prediction. The proposed approach is validated on two IEEE test systems with various wind power penetration levels and compared to existing methods, followed by a discussion of results.

Improving time integration scheme for FET analysis of power system angle stability

This paper presents improved algorithm for numerical analysis of power system angle stability achieved by improvement of the time integration when forming a local system of equations for power system finite elements (FE). Previously developed local system of equations of power system angle stability has been obtained using the generalized trapezoidal rule (? - method). Improvement of accuracy was obtained by using Heun's method. Numerical solutions obtained using Heun?s method and using the generalized trapezoidal rule are compared to Electromagnetic Transients Program (EMTP). It has been shown that Heun?s method yields the results with much higher accuracy comparing to results obtained by generalized trapezoidal rule.

Network allocation of BESS for improving rotor angle stability

This paper presents a novel methodology for an efficient allocation of Battery Energy Storage Systems (BESS) in order to improve rotor angle stability of power systems. The proposal uses a genetic algorithm (GA) specifically designed to solve the allocation problem. The use of GA enables us to evaluate each candidate using time-domain simulations in a set of critical operating conditions and contingencies. This in turn allows us to obtain an accurate estimation of the impact that different BESS allocations may have in the stability of the system. Results from a network based on the IEEE 39-bus New England System demonstrate the benefits of our proposed methodology in terms of improvements in the rotor angle stability that can be achieved and its practical implementation in real-world power systems.

Fuzzy Control Approach for Monomachine Power Systems

Electrical power system angle stability can be improved by a wide variety of controls. Some methods have been used effectively for many years, both at generating plants and in transmission network. In this paper, a fuzzy control strategy for stabilization of the transient faulted power system is presented. The first step is to find the critical clearing time (CCT) by equal area stability criterion and numerical integration. The second interests to fuzzy logic controller. For this last step, we present the nonlinear model with a Takagi-Sugeno fuzzy model (TS). Then, a model-based in fuzzy controller design utilizing the concept of the so-called “Parallel Distributed Compensation” (PDC) is employed. Stability analysis and control design problems can be reduced to linear matrix inequality (LMI) problems. Therefore, they can be solved efficiently in practice by convex programming techniques for LMI’s. A single machine infinite bus system is analysed with the proposed methods.

Rotor angle stability control for DFIG‐integrated power system considering phase‐amplitude characteristics of transient‐grid voltage

The rotor angle stability of power systems under the influence of doubly fed induction generator (DFIG)-based wind turbines has elicited increasing attention as the penetration of wind power increases. The flexible and controllable power capability of DFIG makes it feasible to improve the stability performance of power systems. However, the effects of DFIG on rotor angle stability are not accurate because the phase angle variation of grid voltage has not been considered in existing studies. Current stability control methods may not be effective. This study proposes a rotor angle stability control method considering phase-amplitude characteristics of transient-grid voltage. Variations in both amplitude and phase angle of grid voltage are considered to analyse the effect of DFIG on the rotor angle stability of the DFIG-integrated power system. An evaluation index, which represents the accelerating area variation of the synchronous generator (SGs), is defined to quantise the effect of DFIG. In addition, the controllable power region of DFIG is established by considering DFIG's power constraints and effects on system stability. The control method of rotor angle stability is proposed based on the controllable power region and the evaluation index. Simulation results verify that the effectiveness of proposed method.

Cyber-Physical Attacks Targeting Communication-Assisted Protection Schemes

The dependence of modern societies on electric energy is ever increasing by the emergence of smart cities and electric vehicles. This is while unprecedented number of cyber-physical hazards are threatening the integrity and availability of the power grid on a daily basis. On one hand, physical integrity of power systems is under threat by more frequent natural disasters and intentional attacks. On the other hand, the cyber vulnerability of power grids is on the rise by the emergence of smart grid technologies. This underlines an imminent need for the modeling and examination of power grid vulnerabilities to cyber-physical attacks. This paper examines the vulnerability of the communication-assisted protection schemes like permissive overreaching transfer trip to cyberattacks using a co-simulation platform. The simulation results show that the transient angle stability of power systems can be jeopardized by cyberattacks on the communication-assisted protection schemes. To address this vulnerability, two physical solutions including the deployment of communication channel redundancy, and a more advanced communicated-assisted protection scheme, i.e., directional comparison unblocking scheme (DCUB), are considered and tested. The proposed solutions address the vulnerability of the communication-assisted protection schemes to distributed denial of service attack to some extent. Yet, the simulation results show the vulnerability of the proposed solutions to sophisticated cyberattacks like false data injection attacks. This highlights the need for the development of cyber-based solutions for communication channel monitoring.

Impact of Penetration of Photovoltaic on Rotor Angle Stability of Power System

Impact of Penetration of Photovoltaic on Rotor Angle Stability of Power System

Network-Based Analysis of Small-Disturbance Angle Stability of Power Systems

This paper investigates small-disturbance angle stability of power systems with emphasis on the role of power network topology, which sheds new light on the instability mechanism. We introduce the concepts of active power flow graph and critical lines. It is shown that the inertia of the Laplacian matrix of this graph provides information on the stability and type of an equilibrium point. Then, the instability mechanism is elaborated from the impact of critical lines on the inertia of the Laplacian matrix. A stability criterion in terms of a critical line-based matrix is established. This criterion is a necessary and sufficient condition to judge the stability and type of an equilibrium point. It includes the existing results in the literature and applies to the unsolved cases where the critical lines exist but do not form cutsets. Moreover, we introduce the concept of equivalent weight between a pair of buses. Another stability criterion in terms of the equivalent weight is developed, from which the small-disturbance instability can be interpreted as the “electrical antagonism” between some buses in the power network resulting from the critical lines. The equivalent weight can also be used as a stability index and provides guidance for system operation. The obtained results are illustrated by numerical simulations.

Mechanism Research on the Influence of Large Scale Wind Power Integration on Power System Angle Stability

Base on the equivalent external characteristics of doubly-fed induction generator (DFIG) during the period of the fault and the power characteristic equation of delivery system, a novel method of eliminating equivalent mutual impedance is proposed to research the influence mechanism of different wind power penetration rate, the SG dispatch pattern and siting of wind farms on system transient power angle stability (TPAS) under fault condition are researched. The results show that system power angle characteristics are improved with the increase of the wind power scale. However, when the wind power scale reaches a certain level, the power angle stability promptly deteriorates. The distance of wind farms siting away from a SG group with leading power angle, as well as the generation reduction of the SG group, plays an important role in the improvement of TPAS. The effectiveness of the proposed method is verified by the numerical simulations of the two-machine power system.

Scalable Coordinated Control of Energy Storage Systems for Enhancing Power System Angle Stability

In this paper, a scalable wide area control scheme using distributed model predictive control is proposed to enhance the angle stability of power systems following large disturbances. In this regard, dynamic model of the local subsystems in the multiarea power system is developed for the model predictive controller and each subsystem is controlled by the associated controller. The controller of each subsystem exchanges minimum information with the controllers of the neighboring subsystems to reach the final result. The proposed controller works based on optimality condition decomposition to coordinate the subsystems. In the proposed wide area control system, the available actuators are mechanical power and field voltage controller of a synchronous generator, and energy storage systems (ESS), which are able to provide synchronizing power support. The performance of the proposed transient stability controller is studied in the New England 68-bus test system. The simulation results demonstrate the effectiveness of the proposed method to improve the angle stability of power systems subsequent to severe disturbances in the system.

Impact of Offshore Wind Power Integrated by VSC-HVDC on Power Angle Stability of Power Systems

Offshore wind farm connected to grid by VSC-HVDC loses frequency support for power system, so adding frequency control in wind farm and VSC-HVDC system is an effective measure, but it will change wind farm VSC-HVDC’s transient stability on power system. Through theoretical analysis, concluding the relationship between equivalent mechanical power and electromagnetic power of two-machine system with the active power of wind farm VSC-HVDC, then analyzing the impact of wind farm VSC-HVDC with or without frequency control and different frequency control parameters on angle stability of synchronous machine by EEAC. The validity of theoretical analysis has been demonstrated through simulation in PSCAD/EMTDC.

Controllable powers range and control method of DFIG for transient stability of power system

Wind generation is increasing rapidly in the grid, which has greater impacts on the power system than ever. The impacts are more serious under grid fault. The low-voltage ride through (LVRT) controls of doubly fed induction generators (DFIGs) may change characteristics of synchronous generators (SGs) and threaten the transient stability of power system. However, the influence on the transient stability and even the controllable powers of a DFIG has not been considered in the existing LVRT method. The contributions of the reactive power supplied by a DFIG in the oscillation process of power angle of SG were analysed. The controllable range of powers of a DFIG was researched with consideration of the rotor speed limit. An LVRT control method of a DFIG based on the controllable range was proposed to improve the transient stability of power system. Simulations show that the proposed method could enhance the power angle stability of power system under the condition of avoiding overspeed and out of service of DFIG.

Angle Stability Analysis of Power System with Multiple Operating Conditions Considering Cascading Failure

A method to analyze the angle stability of power system with multiple operating conditions considering cascading failure is proposed in this paper. First, considering stochastic events such as uncertain operation of protection/breaker and system hardware failure, the system operating condition set is determined based on the flow transfer theory and the matrix of transfer probability between different operating conditions is calculated. On this basis, the discrete Markov power system model with multiple operating conditions considering cascading failure is established. And then, construct the Lyapunov functional containing the Markov model, and derive the robust stochastic stability criterion which satisfies the disturbance attenuation degree γ by iteration and the angle stability of power system could be identified according to the criterion using linear matrix inequality tools. Finally, stability index μ is defined to establish the relationship between transfer probability and system stability. Time-domain simulation tests on the IEEE 16-machine 68-bus system verify that, the proposed method could identify the stability of power system with multiple operating conditions effectively, with no need to obtain the operating trajectory of the system. Compared with traditional time-domain simulation method, the computation amount is reduced. Besides, it is simple and easy to implement.

Impacts of High Penetration of DFIG Wind Turbines on Rotor Angle Stability of Power Systems

With the integration of wind power into power systems continues to increase, the impact of high penetration of wind power on power system stability becomes a very important issue. This paper investigates the impact of doubly fed induction generator (DFIG) control and operation on rotor angle stability. Acontrol strategy for both the rotor-side converter (RSC) and grid-side converter (GSC) of the DFIG is proposed to mitigate DFIGs impacts on the system stability. DFIG-GSC is utilized to be controlled as static synchronous compensator (STATCOM) to provide reactive power support during grid faults. In addition, a power system stabilizer (PSS) is implemented in the reactive power control loop of DFIG-RSC. The proposed approaches are validated on a realistic Western System Coordinating Council (WSCC) power system under both small and large disturbances. The simulation results show the effectiveness and robustness of both DFIG-GSC control strategy and PSS to enhance rotor angle stability of power system.