scholarly journals Enhancement of stability margin based on dynamic brake strategy

2019 ◽  
Vol 15 (2) ◽  
pp. 571
Author(s):  
Majli Nema Hawas
Keyword(s):  
Kinetic Energy ◽  
Transient Stability ◽  
Computing Time ◽  
Stability Margin ◽  
Rate Of Change ◽  
System Equation ◽  
Clearing Time ◽  
Dynamic Braking ◽  
Fault Clearance ◽  
Stable Trajectory

The Rate of Change Kinetic Energy (RACKE) method achieves considerable reduction in computing time by virtue of the way that it does not need the solution of system equation beyond fault clearing time. In RACKE method the machine which tends to lose synchronism can be defined as that which has the largest negation RACKE value. The injection of the brake ought to be achieved when RACKE of the machine liable to be unstable reaches its maximum negative value. Elimination happens when RACKE of the machine is zero and disturbance angular velocity passes through zero changing sign from positive to negative. To defining the instant of injection and elimination of brake, RACKE method can be used to investigate the transient stability margin of a power system through evaluation of RACKE value at the instant of fault clearance. The simulation demonstrates that the applying of a braking resistor at the terminal of each of the machines, pulling of synchronism, simultaneously brings the system into stable trajectory. It is clear from the results obtained that dynamic braking depending on the RACKE criterion for insertion and removal of the brake gives excellent results in an enhancement of transient stability margin.

scholarly journals Adaptive Armature Resistance Control of Virtual Synchronous Generators to Improve Power System Transient Stability

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2365
Author(s):  
Daniel Carletti ◽  
Arthur Eduardo Alves Amorim ◽  
Thiago Silva Amorim ◽  
Domingos Sávio Lyrio Simonetti ◽  
Jussara Farias Fardin ◽  
...  
Keyword(s):  
Adaptive Control ◽  
Power System ◽  
Transient Stability ◽  
Short Circuit ◽  
Stability Margin ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Resistance Change ◽  
Clearing Time ◽  
Fault Current Limiters

The growing number of renewable energy plants connected to the power system through static converters have been pushing the development of new strategies to ensure transient stability of these systems. The virtual synchronous generator (VSG) emerged as a way to contribute to the system stabilization by emulating the behavior of traditional synchronous machines in the power converters operation. This paper proposes a modification in the VSG implementation to improve its contribution to the power system transient stability. The proposal is based on the virtualization of the resistive superconducting fault current limiters’ (SFCL) behavior through an adaptive control that performs the VSG armature resistance change in short-circuit situations. A theoretical analysis of the problem is done based on the equal-area criterion, simulation results are obtained using PSCAD, and experimental results are obtained in a Hardware-In-the-Loop (HIL) test bench to corroborate the proposal. Results show an increase in the system transient stability margin, with an increase in the fault critical clearing time (CCT) for all virtual resistance values added by the adaptive control to the VSG operation during the short-circuit.

Distributed Virtual Synchronous Generator approach versus Singular Virtual Synchronous Generator approach: A dynamic stability evaluation

2020 ◽  
pp. 0309524X2097546
Author(s):  
Abdul Waheed Kumar ◽  
Mairaj ud din Mufti ◽  
Mubashar Yaqoob Zargar
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Reactive Power ◽  
Magnetic Energy ◽  
Dynamic Performance ◽  
Synchronous Generator ◽  
Rate Of Change ◽  
Clearing Time ◽  
Magnetic Energy Storage ◽  
Virtual Synchronous Generator

This paper reports the modeling and dynamic performance of a wind penetrated multi-area power system incorporating a Singular Virtual Synchronous Generator (SVSG)/Distributed Virtual Synchronous Generator (DVSG). The active and reactive power controls are achieved by using Superconducting Magnetic Energy Storage (SMES) as Virtual Synchronous Generator (VSG). SMES based VSG control parameters are tuned offline using genetic algorithm (GA). Two topologies of VSGs are considered in this paper: SVSG at lowest inertia generator bus (SVSGGENBUS), SVSG at load bus (SVSGLOADBUS) and DVSG of comparatively smaller rating at three lowest inertia generator buses. A modified 18 machine, 70-bus power system is simulated in MATLAB/Simulink environment. System performance is assessed for two different types of disturbances: step wind disturbance and three-phase fault. The simulation results show that rate of change of frequency (ROCOF), deviations in frequency and voltage are minimized with DVSG. Transient stability measured in terms of critical clearing time (CCT) verifies that CCT is increased by DVSG topology.

Power System Transient Stability Assessment Based on Critical Cutset Transient Stability Available Capacity

2014 ◽  
Vol 615 ◽  
pp. 80-83
Author(s):  
Ke Wang ◽  
Da Hai You ◽  
Ceng Long ◽  
Peng Xu ◽  
Ling Ling Pan ◽  
...  
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Stability Margin ◽  
Control Measures ◽  
System Control ◽  
Prevention Measures ◽  
Power System Control ◽  
Transient Energy Function ◽  
Transient Energy ◽  
Fault Clearance

Aiming at the disadvantages of converting traditional transient stability margin into power system control measures, this paper proposes a new transient stability margin characterization method based on critical cutset transient stability available capacity (TATC). Compared with traditional transient stability margin based on fault clearance time or transient energy function, TATC can directly reflects power system transient stability margin form the view of power which is more conducive for power system planning and operation personnel to grasp system transient stability state, at the same time, is also advantageous for prevention measures and emergency control measures to be developed directly according TATC. Simulation results based on IEEE50 machine 145 bus system show that the proposed TATC can effectively characterize power system transient stability margin.

High Speed Method for CCT Estimation: Fundamental, Implemention and Application in Real-Time Simulation

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Mehdi Zareian Jahromi ◽  
Shahram Montaser Kouhsari
Keyword(s):  
Kinetic Energy ◽  
Power Systems ◽  
Real Time ◽  
High Speed ◽  
Transient Stability ◽  
Computational Cost ◽  
Time Simulation ◽  
Clearing Time ◽  
Low Computational Cost ◽  
Real Time Application

AbstractThis paper proposes a hybrid method based on corrected kinetic energy to determine the critical clearing time. The proposed method structure has been implemented utilizing network preserving model to take details of power systems into consideration. To implement proposed method, the initial critical point is estimated using new concept of equal area criterion. Critical corrected kinetic energy is obtained using method which determines the amount of severity of generator contribution in a fault scenario. Due to the latter, the behavior of AVR and governor are taken into account. From initial and corrected kinetic energy of generators and consequently system, high precision critical clearing time is calculated. In order to validate the proposed method, some comprehensive case studies have been conducted on the IEEE9-bus, IEEE39-bus and IEEE68-bus test systems. Some comprehensiveness in considering the details, simplicity in implementation and low computational cost are the outstanding features of the proposed approach. Also, simulation results approve that the proposed approach can be used in real-time application without loss of any detail in transient stability assessment.

scholarly journals Power System Transient Stability Assessment Based on Snapshot Ensemble LSTM Network

2021 ◽  
Vol 13 (12) ◽  
pp. 6953
Author(s):  
Yixing Du ◽  
Zhijian Hu
Keyword(s):  
Power Systems ◽  
Power System ◽  
Transient Stability ◽  
Short Term Memory ◽  
Risk Function ◽  
Stability Margin ◽  
Risk Level ◽  
Stability Assessment ◽  
Lstm Network ◽  
Hierarchical Assessment

Data-driven methods using synchrophasor measurements have a broad application prospect in Transient Stability Assessment (TSA). Most previous studies only focused on predicting whether the power system is stable or not after disturbance, which lacked a quantitative analysis of the risk of transient stability. Therefore, this paper proposes a two-stage power system TSA method based on snapshot ensemble long short-term memory (LSTM) network. This method can efficiently build an ensemble model through a single training process, and employ the disturbed trajectory measurements as the inputs, which can realize rapid end-to-end TSA. In the first stage, dynamic hierarchical assessment is carried out through the classifier, so as to screen out credible samples step by step. In the second stage, the regressor is used to predict the transient stability margin of the credible stable samples and the undetermined samples, and combined with the built risk function to realize the risk quantification of transient angle stability. Furthermore, by modifying the loss function of the model, it effectively overcomes sample imbalance and overlapping. The simulation results show that the proposed method can not only accurately predict binary information representing transient stability status of samples, but also reasonably reflect the transient safety risk level of power systems, providing reliable reference for the subsequent control.

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