scholarly journals Quasi-Z-Source Inverter-Based Photovoltaic Power System Modeling for Grid Stability Studies

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 508
Author(s):  
Lluís Monjo ◽  
Luis Sainz ◽  
Juan José Mesas ◽  
Joaquín Pedra
Keyword(s):  
Power Systems ◽  
Power System ◽  
System Modeling ◽  
Power Conversion ◽  
System Stability ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Stability Problems ◽  
Sensitivity Studies ◽  
And Control

Quasi-Z-source inverters (qZSIs) are becoming a powerful power conversion technology in photovoltaic (PV) power systems because they allow energy power conversion in a single stage operation. However, they can cause system resonances and reduce system damping, which may lead to instabilities. These stability problems are well known in grid-connected voltage source converter systems but not in quasi-Z-source inverter (qZSI)-based PV power systems. This paper contributes with Matlab/Simulink and PSCAD/EMTDC models of qZSI-based PV power systems to analyze transient interactions and stability problems. These models consider all power circuits and control blocks of qZSI-based PV power systems and can be used in sensitivity studies on the influence of system parameters on stability. PV power system stability is assessed from the proposed models. The causes of instabilities are analyzed from numerical simulations and possible solutions are proposed.

scholarly journals Direct Method-Based Transient Stability Analysis for Power Electronics-Dominated Power Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yanbo Che ◽  
Zihan Lv ◽  
Jianmei Xu ◽  
Jingjing Jia ◽  
Ming Li
Keyword(s):  
Stability Analysis ◽  
Power Systems ◽  
Power Electronics ◽  
Transient Stability ◽  
Direct Method ◽  
System Modeling ◽  
System Stability ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Transient Stability Analysis

With the extensive application of power electronics interfaced nonsynchronous energy sources (NESs) in modern power systems, the system stability especially the transient stability is prominently deteriorated, and it is crucial to find a comprehensive and reasonably simple solution. This paper proposes a direct method-based transient stability analysis (DMTSA) method which concludes the key steps as follows: (1) the system modeling of Lyapunov functions using mixed potential function theory and (2) the stability evaluation of critical energy estimation. A voltage source converter- (VSC-) based HVDC transmission system is simulated in a weak power grid to validate the proposed DMTSA method under various disturbances. The simulation results verify that the proposed method can effectively estimate the transient stability with significant simplicity and generality, which is practically useful to secure the operation and control for power electronics-dominated power systems.

scholarly journals Conformance Testing and Analysis of Synchrophasor Communication Message Structures and Formats for Wide Area Measurement Systems in Smart Grids

2017 ◽  
Vol 6 (2) ◽  
pp. 106
Author(s):  
Adeyemi Charles Adewole ◽  
Raynitchka Tzoneva
Keyword(s):  
Power Systems ◽  
Power System ◽  
Communication Networks ◽  
Smart Grids ◽  
Data Communication ◽  
System Stability ◽  
Area Measurement ◽  
Wide Area ◽  
Protection And Control ◽  
And Control

The renewed quest for situational awareness in power systems has brought about the use of digital signal processing of power system measurements, and the transmission of such data to control centres via communication networks. At the control centres, power system stability algorithms are executed to provide monitoring, protection, and control in order to prevent blackouts. This can be achieved by upgrading the existing Supervisory Control and Data Acquisition (SCADA) systems through the deployment of newly proposed power system synchrophasor-based applications for Wide Area Monitoring, Protection, and Control (WAMPAC). However, this can only be done when there is a complete understanding of the methods and technologies associated with the communication network, message structure, and formats required. This paper presents an analysis of the IEEE C37.118 synchrophasor message framework, message formats, and data communication of synchrophasor measurements from Phasor Measurement Units (PMUs) for WAMPAC schemes in smart grids. A newly designed lab-scale testbed is implemented and used in the practical experimentation relating to this paper. Synchrophasor measurements from the PMUs are captured using a network protocol analyzer software-Wireshark, and the compliance of the synchrophasor message structures and formats captured was compared to the specifications defined in the IEEE C37.118 synchrophasor standard.

scholarly journals A stabilising control strategy for Cyber-Physical Power Systems

2018 ◽  
Author(s):  
Etinosa Ekomwenrenren ◽  
Hatem Alharbi ◽  
Taisir Elgorashi ◽  
Jaafar Elmirghani ◽  
Petros Aristidou
Keyword(s):  
Power Systems ◽  
Power System ◽  
Control Strategy ◽  
Physical Nature ◽  
System Stability ◽  
Wide Area ◽  
Equivalent Model ◽  
Communication Infrastructure ◽  
Damping Controllers ◽  
And Control

The cyber-physical nature of electric power systems has increased immensely over the last decades, with advanced communication infrastructure paving the way. It is now possible to design wide-area controllers, relying on remote monitor and control of devices, that can tackle power system stability problems more effectively than local controllers. However, their performance and security relies extensively on the communication infrastructure and can make power systems vulnerable to disturbances emerging on the cyber side of the system. In this paper, we investigate the effect of communication delays on the performance and security of wide-area damping controllers (WADC) designed to stabilise oscillatory modes in a Cyber-Physical Power System (CPPS). We propose a rule-based control strategy that combines wide-area and traditional local stabilising controllers to increase the performance and maintain the security of CPPS. The proposed strategy is validated on a reduced CPPS equivalent model of Great-Britain (GB).

scholarly journals Load Flow Analysis in Hybrid AC-DC Transmission Network

2021 ◽  
pp. 617-624
Author(s):  
Ajith M ◽  
Dr. R. Rajeswari
Keyword(s):  
Power Systems ◽  
Power System ◽  
Transmission Lines ◽  
Power Flow ◽  
Reactive Power ◽  
Short Circuit ◽  
Flow Analysis ◽  
Load Flow ◽  
System Stability ◽  
And Control

Power-flow studies are of great significance in planning and designing the future expansion of power systems as well as in determining the best operation of existing systems. Technologies such as renewables and power electronics are aiding in power conversion and control, thus making the power system massive, complex, and dynamic. HVDC is being preferred due to limitations in HVAC such as reactive power loss, stability, current carrying capacity, operation and control. The HVDC system is being used for bulk power transmission over long distances with minimum losses using overhead transmission lines or submarine cable crossings. Recent years have witnessed an unprecedented growth in the number of the HVDC projects. Due to the vast size and inaccessibility of transmission systems, real time testing can prove to be difficult. Thus analyzing power system stability through computer modeling and simulation proves to be a viable solution in this case. The motivation of this project is to construct and analyze the load flow and short circuit behavior in an IEEE 14 bus power system with DC link using MATLAB software. This involves determining the parameters for converter transformer, rectifier, inverter and DC cable for modelling the DC link. The line chosen for incorporation of DC link is a weak bus. This project gives the results of load flow and along with comparison of reactive power flow, system losses, voltage in an AC and an AC-DC system.

scholarly journals Bi-Level Dispatch and Control Architecture for Power System in China Based on Grid-Friendly Virtual Power Plant

2021 ◽  
Vol 11 (3) ◽  
pp. 1282
Author(s):  
Qingwen Xu ◽  
Yongji Cao ◽  
Hengxu Zhang ◽  
Wen Zhang ◽  
Vladimir Terzija
Keyword(s):  
Power Plant ◽  
Power Systems ◽  
Power System ◽  
Renewable Energy Sources ◽  
System Stability ◽  
Control Architecture ◽  
Virtual Power ◽  
Virtual Power Plant ◽  
Virtual Power Plants ◽  
And Control

Non-synchronous renewable energy sources (RESs) have strong volatility and low inertia, which brings about great challenges on the accommodation of RESs and the security and stability of power systems. This paper proposes a bi-level power system dispatch and control architecture based on the grid-friendly virtual power plant (GVPP), so as to accommodate RESs flexibly and securely. The typical dispatch and control system of the power system in China is presented, and the particular challenges stemming from non-synchronous RESs are analyzed. The functional requirements, concept, and fundamental design of the GVPP are provided, which is distinguished from traditional virtual power plants (VPPs) for its active participation in power system stability control. Based on the cloud platform, a bi-level dispatch and control architecture considering two objectives is established. First, in the inner level, the GVPP operates to promote the accommodation of RESs under normal condition. Then, from the perspective of out-level power systems, GVPPs serve as spinning reserves for power support under contingencies. Besides, the key problems to be solved in the development of the GVPP-based architecture are summarized. Although the architecture is proposed for the power system in China, it can be applied to any power systems with similar challenges.

scholarly journals The Influence of VSC–HVDC Reactive Power Control Mode on AC Power System Stability

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1677 ◽  
Author(s):  
Ying Wang ◽  
Youbin Zhou ◽  
Dahu Li ◽  
Dejun Shao ◽  
Kan Cao ◽  
...  
Keyword(s):  
Power System ◽  
Power Control ◽  
Reactive Power ◽  
Dynamic Responses ◽  
System Stability ◽  
Control Mode ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Reactive Power Control ◽  
Margin Control

Voltage source converter-based high-voltage direct current (VSC-HVDC) has the advantage of fast and independent controllability on active and reactive power. This paper focuses on effects of commonly proposed reactive power control modes, constant reactive power control and AC voltage margin control. Based on the mathematical model of single machine infinity equivalent system with embedded VSC-HVDC, the influence of VSC-HVDC with different reactive power control strategies on transient stability and dynamic stability of the AC system is studied. Then case studies were conducted with a realistic model of grid. The dynamic responses of AC/DC systems for different VSC-HVDC reactive power control modes were compared in detail. It is shown that compared to constant reactive power control, AC voltage margin control can provide voltage support to enhance the transient angle stability of an AC system. However, the fluctuant reactive power injected into a weak AC system may adversely affect power system oscillation damping for VSC-HVDC with AC voltage margin control, if the parameters of the controller have not been optimized to suppress the low-frequency oscillation. The results of this paper can provide certain reference for the decision of an appropriate VSC-HVDC reactive power control mode in practice.

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