UHVDC Islanded Operation System Ultralow-Frequency Oscillation and Its Countermeasures

2021 ◽  
Vol 44 (2) ◽  
pp. 110-117
Author(s):  
Wei Li ◽  
Aniruddha M. Gole ◽  
Iman Kaffashan ◽  
Xiangning Xiao
Keyword(s):  
Frequency Oscillation ◽  
Operation System ◽  
Ultralow Frequency ◽  
Islanded Operation

A coordinated damping control for ultralow-frequency oscillation in a DC isolated system

2019 ◽  
pp. 166-174
Author(s):  
Xin Zhou ◽  
Peng He ◽  
Ningning Ma* ◽  
W.e.i. Deng ◽  
Zhenpeng Li ◽  
...  
Keyword(s):  
Frequency Oscillation ◽  
Ultralow Frequency ◽  
Damping Control

scholarly journals Small-Signal Stability Analysis of Photovoltaic-Hydro Integrated Systems on Ultra-Low Frequency Oscillation

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1012 ◽  
Author(s):  
Sijia Wang ◽  
Xiangyu Wu ◽  
Gang Chen ◽  
Yin Xu
Keyword(s):  
Dynamic Model ◽  
Oscillation Mode ◽  
Low Frequency ◽  
Small Signal ◽  
Frequency Oscillation ◽  
Ultralow Frequency ◽  
Oscillation Modes ◽  
Pv Generation ◽  
The Impact ◽  
Signal Dynamic

In recent years, ultralow-frequency oscillation has repeatedly occurred in asynchronously connected regional power systems and brought serious threats to the operation of power grids. This phenomenon is mainly caused by hydropower units because of the water hammer effect of turbines and the inappropriate Proportional-Integral-Derivative (PID) parameters of governors. In practice, hydropower and solar power are often combined to form an integrated photovoltaic (PV)-hydro system to realize complementary renewable power generation. This paper studies ultralow-frequency oscillations in integrated PV-hydro systems and analyzes the impacts of PV generation on ultralow-frequency oscillation modes. Firstly, the negative damping problem of hydro turbines and governors in the ultralow-frequency band was analyzed through the damping torque analysis. Subsequently, in order to analyze the impact of PV generation, a small-signal dynamic model of the integrated PV-hydro system was established, considering a detailed dynamic model of PV generation. Based on the small-signal dynamic model, a two-zone and four-machine system and an actual integrated PV-hydro system were selected to analyze the influence of PV generation on ultralow-frequency oscillation modes under different scenarios of PV output powers and locations. The analysis results showed that PV dynamics do not participate in ultralow-frequency oscillation modes and the changes of PV generation to power flows do not cause obvious changes in ultralow-frequency oscillation mode. Ultra-low frequency oscillations are mainly affected by sources participating in the frequency adjustment of systems.

Verification of Optimized Energy-Saving Train Scheduling Utilizing Automatic Train Operation System

2019 ◽  
Vol 139 (6) ◽  
pp. 580-587
Author(s):  
Shoichiro Watanabe ◽  
Yasuhiro Sato ◽  
Takafumi Koseki ◽  
Takeshi Mizuma ◽  
Ryuji Tanaka ◽  
...  
Keyword(s):  
Energy Saving ◽  
Operation System ◽  
Train Scheduling ◽  
Train Operation ◽  
Automatic Train Operation

High-Frequency Oscillation and Chronic Lung Disease in Very Low Birth Weight Infants

PEDIATRICS ◽  
2001 ◽  
Vol 108 (1) ◽  
pp. 212-214
Author(s):  
J. P. Shenai; ◽  
P. Rimensberger; ◽  
U. Thome ◽  
F. Pohlandt; ◽  
P. Rimensberger
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Lung Disease ◽  
Chronic Lung Disease ◽  
High Frequency ◽  
Very Low Birth Weight ◽  
High Frequency Oscillation ◽  
Frequency Oscillation ◽  
Low Birth Weight Infants

ACCOUNTING SYSTEM DESIGN FOR THE OPERATION OF RENTAL FLATS AND SPORTS VENUE OF RIAU PROVINCE

Jurnal Niara ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 29-34
Author(s):  
Neneng Salmiah ◽  
Fahmi Oemar ◽  
Reni Farwitawati
Keyword(s):  
System Design ◽  
Public Service ◽  
Financial Management ◽  
Development Program ◽  
Design System ◽  
Accounting System ◽  
Service Agency ◽  
Operation System ◽  
Management Procedure ◽  
The Government

The study aimed at conducting an analysis towards the operation of Athlete Homestead for the National Sports Week in 2012 belonging to Riau Province. Regarding the Finance Operation System in the form of Sub-district Development Program-Regional Public Service Agency (PPK BLUD), the researcher designed the Accounting System for the Regional Public Service Agency of the Rental Flats and Sports Venue. The data analysis in this study used the descriptive qualitative method by describing the accounting system design for the operation of Rental Flats and Sports Venue through the Sub-district Development Program-Regional Public Service Agency (PPK BLUD) with the procedure comprising: designing the rent system and procedure of the Rental Flats and Sports Venue, designing the system of cash management from the rent income, implementing focused-group discussion with the related parties and the government, working on the policy improvement draft for the operation of the Rental Flats and Sports Venue belonging to Riau Province.Based on the result of the study and discussion, it can be concluded that in order to improve the effectiveness of the service and operation of Rental Flats and Sports Venue with sound business practice, it is necessary to implement the Finance Operation System in the form of Sub-district Development Program-Regional Public Service Agency (PPK BLUD). The design system of the Sub-district Development Program-Regional Public Service Agency (PPK BLUD) comprising the organization chart, the transaction proof document, and the financial management procedure

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