scholarly journals Dynamic Stability Enhancement Through the Application of Stabilizers of Electromechanical Oscillations

2021 ◽  
Vol 70 (1) ◽  
pp. 14-21
Author(s):  
Vladimir Franki ◽  
Alfredo Višković ◽  
Vladimir Valentić
Keyword(s):  
Power Systems ◽  
Power System ◽  
Dynamic Stability ◽  
Synchronous Generator ◽  
Response Analysis ◽  
Electromechanical Oscillations ◽  
Generator Model ◽  
Key Issues ◽  
The Stability ◽  
Stability Enhancement

Power system dynamic stability is one of key issues system engineers face. Oscillations that regularly occur in the system, limit the transmission capability of the network. The need to study the stability of power systems has been increasingly growing along with the development of power systems and their grouping into large interconnections. The focus of this paper is determining the dynamic stability of a synchronous generator, and thus the power system, by applying the general theory of stability of dynamic systems. Furthermore, the procedure for the initial adjustment of the parameters of a conventional (IEEE3 type PSS1A) stabilizer of electromechanical oscillations is briefly described based on the frequency response analysis of a linear generator model also known as the Heffron-Phillips generator model.

Synthesizing a Power System Stabilizer Using the Fuzzy Logic and Neural Network Methods

2021 ◽  
pp. 22-30
Author(s):  
Kahramon R. ALLAEV ◽  
◽  
Tokhir F. MAKHMUDOV ◽  
Keyword(s):  
Neural Network ◽  
Fuzzy Logic ◽  
Power Systems ◽  
Power System ◽  
Fuzzy Logic Controller ◽  
Power Transmission ◽  
Low Frequency ◽  
Synchronous Generator ◽  
Electromechanical Oscillations ◽  
The Stability

Power systems are large non-linear systems that are often subject to low frequency electromechanical oscillations with a frequency of 0.5–2.5 Hz. Power system stabilizers (PSS) are commonly used as effective and economically efficient means to dampen electromechanical oscillations of generators and increase the stability of power systems. PSS can increase the power transmission stability limits by adding a stabilizing signal through the channels of the automatic excitation control system. The article presents the results of training a neural network based on which a fuzzy logic PSS is obtained for increasing the stability of electric power systems. The synchronous generator rotor speed deviation and acceleration were taken as input data for the fuzzy logic controller. These variables have a significant effect on damping the rotor's electromechanical oscillations. The characteristics of the power system equipped with the proposed fuzzy logic based PSS are compared with its characteristics with a PSS with non-optimized parameters and without a PSS.

scholarly journals Dynamics Analysis Using Koopman Mode Decomposition of a Microgrid Including Virtual Synchronous Generator-Based Inverters

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4581
Author(s):  
Yuko Hirase ◽  
Yuki Ohara ◽  
Naoya Matsuura ◽  
Takeaki Yamazaki
Keyword(s):  
Power System ◽  
System Dynamics ◽  
Dimensional Space ◽  
Supply And Demand ◽  
Transient State ◽  
Synchronous Generator ◽  
Response Analysis ◽  
Power System Dynamics ◽  
Mode Decomposition ◽  
Virtual Synchronous Generator

In the field of microgrids (MGs), steady-state power imbalances and frequency/voltage fluctuations in the transient state have been gaining prominence owing to the advancing distributed energy resources (DERs) connected to MGs via grid-connected inverters. Because a stable, safe power supply and demand must be maintained, accurate analyses of power system dynamics are crucial. However, the natural frequency components present in the dynamics make analyses complex. The nonlinearity and confidentiality of grid-connected inverters also hinder controllability. The MG considered in this study consisted of a synchronous generator (the main power source) and multiple grid-connected inverters with storage batteries and virtual synchronous generator (VSG) control. Although smart inverter controls such as VSG contribute to system stabilization, they induce system nonlinearity. Therefore, Koopman mode decomposition (KMD) was utilized in this study for consideration as a future method of data-driven analysis of the measured frequencies and voltages, and a frequency response analysis of the power system dynamics was performed. The Koopman operator is a linear operator on an infinite dimensional space, whereas the original dynamics is a nonlinear map on a finite state space. In other words, the proposed method can precisely analyze all the dynamics of the power system, which involve the complex nonlinearities caused by VSGs.

scholarly journals Dual Two-Level Voltage Source Inverter Virtual Inertia Emulation: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1160
Author(s):  
Mohammad Ali Dashtaki ◽  
Hamed Nafisi ◽  
Amir Khorsandi ◽  
Mojgan Hojabri ◽  
Edris Pouresmaeil
Keyword(s):  
Harmonic Distortion ◽  
Synchronous Generator ◽  
Voltage Source ◽  
Small Signal ◽  
Voltage Source Inverter ◽  
Nonlinear Loads ◽  
Virtual Inertia ◽  
The Stability ◽  
Stability Enhancement ◽  
Oscillation Damping

In this paper, the virtual synchronous generator (VSG) concept is utilized in the controller of the grid-connected dual two-level voltage source inverter (DTL VSI). First, the topology of the VSG and the DTL VSI are presented. Then, the state-space equations of the DTL VSI and the grid-connected two-level voltage source inverter (TL VSI), regarding the presence of the phase-locked loop (PLL) and the VSG, are given. Next, the small-signal modeling of the DTL VSI and the TL VSI is realized. Eventually, the stability enhancement in the DTL VSI compared with the TL VSI is demonstrated. In the TL VSI, large values of virtual inertia could result in oscillations in the power system. However, the ability of the DTL VSI in damping oscillations is deduced. Furthermore, in the presence of nonlinear loads, the potentiality of the DTL VSI in reducing grid current Total Harmonic Distortion (THD) is evaluated. Finally, by using a proper reference current command signal, the abilities of the DTL VSI and the TL VSI in supplying nonlinear loads and providing virtual inertia are assessed simultaneously. The simulation results prove the advantages of the DTL VSI compared with the TL VSI in virtual inertia emulation and oscillation damping, which are realized by small-signal analysis.

scholarly journals Overview of Methods for Determining Parameters of Synchronous Generators

2020 ◽  
Vol 20 (4) ◽  
pp. 103-113
Keyword(s):  
Power Systems ◽  
Computational Models ◽  
Meta Analysis ◽  
Measurement Data ◽  
Synchronous Generator ◽  
Adaptive Model ◽  
Operational Control ◽  
Synchronous Generators ◽  
Computing Power ◽  
The Stability

A synchronous generator is one of the key elements of any power system, having a significant impact on the stability and reliability of consumers’ power supply. Nowadays, the power systems emergency and operational control issues are being solved using computational models, the parameters whereof are determined using the reference data, or the data obtained during testing. High dependence of the models’ parameters on various external factors leads to a significant decrease in the accuracy of solving the issues of emergency and operational control. Identification based on the traditional telemetry systems or synchrophasor measurements is used to improve the accuracy of parameters of the power systems’ computational models. The purpose of this research lies in a meta-analysis of the available studies aimed at developing a methodology for determining parameters of a synchronous generator on the basis of measurement data. Russian and foreign studies were analyzed and grouped to achieve this goal. After that, for each group, advantages, disadvantages, and the area of application were identified. As a result, it is shown that the existing methods for determining parameters of synchronous generators based on measurement data cannot adapt to the source dataset and also require significant computing power. As a way to overcome these shortcomings, an adaptive model of a synchronous machine is proposed.

Techniques for the Identification of Critical Nodes Leading to Voltage Collapse in a Power System

2018 ◽  
Vol 19 (2) ◽  
Author(s):  
Isaiah Adebayo ◽  
Adisa Jimoh ◽  
Adedayo Yusuff
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Eigenvalue Decomposition ◽  
Step Size ◽  
Suggested Approach ◽  
Voltage Instability ◽  
Critical Nodes ◽  
Voltage Stability Enhancement ◽  
Stability Enhancement

AbstractThis paper proposes two techniques for the identification of critical buses in a power system. The technique of Network Structural Theory Participation Factor (NSTPF) depends on the network structural interconnection of buses as captured by the admittance matrix of the system and is formulated based on the fundamental circuit theory law using eigenvalue decomposition method. Another power flow based technique which depends on the system maximum loadability, the system step size among other factors is also proposed. Traditional power flow based techniques are used as benchmarks to determine the significance of the proposed methods. To ensure voltage stability enhancement, STATCOM FACTS device is installed at the selected weak load buses of the practical Nigerian 24 bus and IEEE 30 bus test systems. The results of the simulation obtained show that, the suggested approach of NSTPF is more suitable in the identification of weak buses that are liable to voltage instability in power systems as it requires less computational burden and also saves time compared to techniques based on power flow solutions.

scholarly journals An Autonomous Power-Frequency Control Strategy Based on Load Virtual Synchronous Generator

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 433 ◽  
Author(s):  
Jiangbei Han ◽  
Zhijian Liu ◽  
Ning Liang ◽  
Qi Song ◽  
Pengcheng Li
Keyword(s):  
Power Systems ◽  
Dynamic Stability ◽  
Control Strategy ◽  
Load Capacity ◽  
Frequency Control ◽  
Synchronous Generator ◽  
Active Power ◽  
Power Oscillation ◽  
Power Frequency ◽  
Virtual Synchronous Generator

With the increasing penetration of the hybrid AC/DC microgrid in power systems, an inertia decrease of the microgrid is caused. Many scholars have put forward the concept of a virtual synchronous generator, which enables the converters of the microgrid to possess the characteristics of a synchronous generator, thus providing inertia support for the microgrid. Nevertheless, the problems of active power oscillation and unbalance would be serious when multiple virtual synchronous generators (VSGs) operate in the microgrid. To conquer these problems, a VSG-based autonomous power-frequency control strategy is proposed, which not only independently allocates the power grid capacity according to the load capacity, but also effectively suppresses the active power oscillation. In addition, by establishing a dynamic small-signal model of the microgrid, the dynamic stability of the proposed control strategy in the microgrid is verified, and further reveals the leading role of the VSG and filter in the dynamic stability of microgrids. Finally, the feasibility and effectiveness of the proposed control strategy are validated by the simulation results.

Summary of the Stability Chanllenges and Safe Operation of Power Systems in View of Dispatching

2014 ◽  
Vol 960-961 ◽  
pp. 1588-1591
Author(s):  
Xiang Dong Zhao ◽  
Xin Zhao ◽  
Ming Jun Lv ◽  
Jian Guo Liu ◽  
Feng Zhen Liu ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Rapid Development ◽  
Power Grids ◽  
System Stability ◽  
Stable Operation ◽  
Safe Operation ◽  
The Stability ◽  
Continuous Power ◽  
Grid Market

The Internet and the gradual implementation of the continuous power grid market in recent years make the power system more complex under different operating environment. Safe and stable operation of power grids have become increasingly important . With the rapidf development of the grid and constant innovation, safe and stable operation also has a new requirement , because the rapid development of the power system brings more This paper analyzes the causes of blackouts and reviews security of the power system stability problems related to measures on the security and stability of the power system operation .

Analysis and Stability Enhancement of DG Sourced Power System with Modified AVR and PSS

2013 ◽  
Vol 768 ◽  
pp. 313-316
Author(s):  
P. Sivakumar ◽  
C. Birindha
Keyword(s):  
Power System ◽  
Distribution System ◽  
Transient Stability ◽  
Probabilistic Approach ◽  
Small Signal Stability ◽  
Signal Stability ◽  
The Stability ◽  
System Stabilizer ◽  
Stability Issues ◽  
Stability Enhancement

Distribution system is facing stability issues with integration of distributed generators and controllers. This proposed method presents the stability of renewable energy based distribution system with varying energy source considering intermittent nature of wind and solar energy using probabilistic approach. The system is supplied by conventional and distributed generating sources like PV and wind. Monte Carlo approach is used for predicting the wind and solar power uncertainties. Proposed work explains both small signal stability and transient stability enhancement of DG sourced power system with power system stabilizer and automatic voltage regulator .It is carried out in is 4 machine 10 bus system. The initial simulation has been carried out using MATLAB/SIMULINK.

scholarly journals Stability Improvement of DFIG-Based Wind Farm Integrated Power System Using ANFIS Controlled STATCOM

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4707
Author(s):  
Varun Kumar ◽  
Ajay Shekhar Pandey ◽  
Sunil Kumar Sinha
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Farm ◽  
Fuzzy Logic Controller ◽  
Stability Control ◽  
Frequency Domain Method ◽  
Damping Properties ◽  
Inference System ◽  
The Stability ◽  
Damping Controller

The stability of the control grid is a critical prerequisite for a safe and efficient power system service. A thorough knowledge of the effects of the power system volatility is essential for the effective study and control of power systems. This paper presents the simulation outcome of a multimachine power network implemented by a wind farm (WF) utilizing a static synchronous compensator (STATCOM) for better stability control objectives. A similarly aggregated double-fed induction generator (DFIG) powered by a gearbox analogy with an equally aggregated wind turbine (WT) determines the operating output of the wind farm. A proportional–integral–derivative controller (PID)-based damping controller, PID including Fuzzy Logic Controller (FLC), and an adaptive network-based fuzzy inference system (ANFIS) controller of the proposed SATCOM are intended to add sufficient damping properties to the dominating modes of the examined system during diverse working circumstances. To assess the feasibility of the suggested control schemes, a frequency-domain method concentrated on a linearized mathematical structure layout utilizing a time-domain strategy centered on a nonlinear configuration of the device that is subjected to severe fault on the attached bus was carried out consistently. A STATCOM damping controller is configured using the ANFIS method to apply appropriate damping properties to the device’s decisive modes being evaluated under various test conditions. From the findings of the comparative simulation, it can be inferred that the suggested STATCOM along with the planned ANFIS is seen as comparable to STATCOM with PID and STATCOM with PID plus FLC to increase the stability of the studied device.

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