scholarly journals On-Site Engineering Test of Active Support Control for the PV Station and Wind Farm in the AC-DC Hybrid Power Grid under Extreme Fault Conditions

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xiao-ling Su ◽  
Lai-jun Chen ◽  
Jun Yang ◽  
Zhengxi Li ◽  
Peng Zhou ◽  
...  

Power systems have developed significantly because of the increasing share of renewable energy sources (RESs). Despite the advantages, they also bring inevitable challenges to power system stability, especially under extreme fault conditions. This paper presents a practical active support control strategy for RESs to support the power grid under extreme fault conditions. The proof process is taken in an AC-DC hybrid power grid integrated with large capacity of PV stations and wind farms. The on-site engineering test results reflect that RESs bring potential risks in the AC-DC hybrid power grid operation and validate the excellent engineering practical features of the proposed control strategy. In addition, test results also reveal predisposing factors of power system instability which are missing in the simulation and fault simulation device-based testing results. They prove the outstanding advantages of on-site engineering tests.

Author(s):  
Junrong Xia ◽  
Pan Zhao ◽  
Yiping Dai

Due to the intermittence and fluctuation of wind resource, the integration of large wind farms in a power grid introduces an additional stochastic component to power system scheduling. This always brings challenges to maintain the stability of power system. Integrating gas turbine units with wind farms can compensate their output fluctuation. In this paper, a methodology for the operation scheduling of a hybrid power system that consists of a large wind farm and gas turbine units is presented. A statistical model based on numerical weather prediction is used to forecast power output of the wind farm for the next 24 hours at quarter-hour intervals. Forecasts of wind power are used for optimizing the operation scheduling. In order to study the dynamic performance of the proposed hybrid power system, dynamic modeling of this hybrid power system is addressed. Wind farm and gas turbine units are integrated through an AC bus, and then connected to a power grid. An aggregated model of the wind farm and detailed models of gas turbine units are developed, and are implemented using MATLAB/Simulink. Simulation studies are carried out to evaluate the system performance using real weather data. The simulation results show that the proposed hybrid power system can compensate fluctuating wind power effectively and make wind power more reliable.


2020 ◽  
Vol 10 (24) ◽  
pp. 9034
Author(s):  
Junji Tamura ◽  
Atsushi Umemura ◽  
Rion Takahashi ◽  
Atsushi Sakahara ◽  
Fumihito Tosaka ◽  
...  

The penetration level of large-scale wind farms into power systems has been increasing significantly, and the frequency stability and transient stability of the power systems during and after a network fault can be negatively affected. This paper proposes a new control method to improve the stability of power systems that are composed of large wind farms, as well as usual synchronous generators. The new method is a coordinated controlling method between an adjustable-speed pumping generator (ASG) and a battery. The coordinated system is designed to improve power system stability during a disconnection in a fixed-rotor-speed wind turbine with a squirrel cage-type induction generator (FSWT-SCIG)-based wind farm due to a network fault, in which a battery first responds quickly to the system frequency deviation due to a grid fault and improves the frequency nadir, and then the ASG starts to supply compensatory power to recover the grid frequency to the rated frequency. The performance of the proposed system was confirmed through simulation studies on a power system model consisting of usual synchronous generators (SGs), an ASG, a battery, and an SCIG-based wind farm. Simulation results demonstrated that the proposed control system can enhance the stability of the power system effectively.


2012 ◽  
Vol 433-440 ◽  
pp. 1794-1801 ◽  
Author(s):  
Jian Dong Duan ◽  
Rui Li ◽  
Lin An

Squirrel-cage induction generator (SCIG), as its structural and economic advantages, has been widely utilized in large wind farms in China. However, the large wind farm composed of induction generators will cause obvious problems to the power system stability due to the dependency on reactive power. At the same time, Doubly-fed induction generator (DFIG), as a new type of wind turbine generator, has excellent dynamic characteristics for operation of wind farms. With the increase in penetration of wind power in power systems, more and more wind farms will use both SCIG and DFIG. In this case, the dynamic characteristic of wind farm on power systems is becoming an important issue especially in terms of the voltage stability. This article is to show by means of simulations the dynamic performance of wind farm linked to power system under the circumstances of network disturbances. Furthermore, the interaction between the SCIGs and DFIGs has also been investigated. A detailed model of wind farms is presented through the plat root of MATLAB/SIMULINK. The simulation results demonstrate that the DFIG applications will largely improve the dynamic performance of wind farm in certain conditions, if the DFIGs could be applied reasonably, the voltage stability of the wind farm will be largely improved and even low voltage ride through(LVRT) characteristic of SCIGs, which may be a good solution to reduce the high dependence of costly reactive power compensation equipment(Some flexible AC transmission systems devices like SVC, STATCOM) to some extent.


Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 115
Author(s):  
Nasser Hosseinzadeh ◽  
Asma Aziz ◽  
Apel Mahmud ◽  
Ameen Gargoom ◽  
Mahbub Rabbani

The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.


2018 ◽  
Author(s):  
Etinosa Ekomwenrenren ◽  
Hatem Alharbi ◽  
Taisir Elgorashi ◽  
Jaafar Elmirghani ◽  
Petros Aristidou

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).


Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3506
Author(s):  
Minas Patsalides ◽  
Christina N. Papadimitriou ◽  
Venizelos Efthymiou ◽  
Roberto Ciavarella ◽  
Marialaura Di Somma ◽  
...  

The high penetration of the Renewable Energy Sources and other emerging technologies likely to be installed in future power grids will pose new operational challenges to grid operators. One of the main issues expected to affect the operation of the power grid is the impact of inverter-based technologies to the power system inertia and, hence, to system stability. Consequently, the main challenge of the future grid is the evaluation of the frequency stability in the presence of inverter-based systems and how the aforementioned technology can support frequency stability without the help of the rotating masses of the traditional power grid systems. To assess the above problem, this paper proposes a methodology to evaluate the frequency stability in a projection of the real distribution grid in Cyprus with the time horizon to be the year 2030. The power grid under investigation is evaluated with and without the presence of smart hierarchical controllers for providing support to the power system under disturbance conditions. The advanced controllers were applied to manage the available power resource in a fast and effective manner to maintain frequency within nominal levels. The controllers have been implemented in two hierarchical levels revealing useful responses for managing low-inertia networks. The first is set to act locally within a preselected area and the second level effectively supporting the different areas for optimal operation. After undertaking a significant number of simulations for time-series of one year, it was concluded from the results that the local control approach manages to minimize the frequency excursion effectively and influence all related attributes including the rate of change of frequency (RoCoF), frequency nadir and frequency zenith.


Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1067
Author(s):  
Youming Cai ◽  
Zheng Li ◽  
Xu Cai

It is important to reduce the impact of the high penetration of wind power into the electricity supply for the purposes of the security and stability of the power grid. As such, the inertia capability of wind farms has become an observation index. The existing control modes cannot guarantee the wind turbine to respond to the frequency variation of the grid, hence, it may lead to frequency instability as the penetration of wind power gets much higher. For the stability of the power grid, a simple and applicable method is to realize inertia response by controlling wind farms based on a high-speed communication network. Thus, with the consideration of the inertia released by a wind turbine at its different operating points, the inertia control mechanism of a doubly-fed wind turbine is analyzed firstly in this paper. The optimal exit point of inertia control is discussed. Then, an active power control strategy for wind farms is proposed to reserve the maximum inertia under a given power output constraint. Furthermore, turbines in a wind farm are grouped depending on their inertia capabilities, and a wind farm inertia control strategy for reasonable extraction of inertia is then presented. Finally, the effectiveness of the proposed control strategy is verified by simulation on the RT-LAB (11.3.3, OPAL-RT TECHNOLOGIES, Montreal, Quebec, Canada) platform with detailed models of the wind farm.


Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2705 ◽  
Author(s):  
Triantafyllia Nikolaou ◽  
George S. Stavrakakis ◽  
Konstantinos Tsamoudalis

The aim of the present paper is to investigate the use of the site “Potamon” Dam in the Prefecture of Rethymnon, Crete island, Greece, as a “virtual” renewable electricity supply of a pumped storage plant (PSP) in order to save and exploit the maximum possible part of the rejected wind energy of the autonomous power system of the Crete island. Taking into account the annual time series of the rejected power of the Crete power grid, the present research work targets the optimal configuration of the proposed PSP power station, including the sizing of its individual components as well as the determination of the capacity it could guarantee in order to be economically viable. The rejected electric energy from the actually operating wind farm production, which is not possible to be absorbed by the grid of Crete due to its stable operation limitations, could be absorbed by the here proposed pump storage plant (PSP) and converted to hydraulic energy. This can be achieved by pumping the water from the lower reservoir, which is the existing reservoir of the site “Potamon” Dam, with a storage capacity of about 22.5 million m3, up to the upper reservoir, which must be constructed accordingly. For the proposed PSP’s optimal size determination, established financial indices are used as an evaluation criterion for an investment life cycle of 25 years. The proposed PSP optimization is based on the dynamic mathematical model of the simulation results of the PSP’s hourly operation when incorporated in the Crete power grid for a whole year, performed in the Matlab 2016b computational environment (The MathWorks, Inc., Natick, MA, USA). The results of this research demonstrate the PSP’s technical feasibility and determine the PSP’s optimal CAPEX and the PSP’s whole life-time financial indicators in order that the whole investment be viable. Furthermore, the appropriate selling prices of the electricity produced from the proposed PSP were determined to achieve the PSP’s financial viability. The results comprise the key elements to prove the necessity for the establishment a.s.a.p. of the appropriate legal framework in order to have authorization to exploit the rejected RES (renewable energy sources) electric energy or the major part of it through PSPs, in priority in both the non-interconnected, as well as the interconnected power systems.


2011 ◽  
Vol 354-355 ◽  
pp. 989-992
Author(s):  
An Lin

Squirrel-cage induction generator (SCIG) has been widely utilized in large wind farms in China. However, the large wind farm composed of induction generators will cause obvious power system stability problems due to the dependency on reactive power. Doubly-fed induction generator (DFIG) has excellent dynamic characteristics of wind farm operations. With the increasing of wind power penetration in power systems, more and more wind farms use both SCIG and DFIG. This paper firstly analyzes the the dynamic characteristic of wind farm on power systems, especially in terms of the voltage stability. Then the interaction between the SCIGs and DFIGs is also investigated. A detailed simulation model of wind farms is presented by means of MATLAB. The simulation results demonstrate that the DFIG applications will improve the voltage stability of the wind farm largely and the low voltage ride through characteristics of SCIG to some extend.


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