Search for: under-voltages
Presenting Practical Solutions to Mitigate the Effects of Fault Induced Delayed Voltage Recovery (FIDVR) Phenomenon on the Special Protection Systems of Power Network, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi ; Hajipoor, Ehsan
Fault Induced delayed voltage Recovery (FIDVR) is a phenomenon that occurs due to the behavior of motor loads such as A/C loads during voltage drop due to fault occurrence in the transmission, sub-transmission and distribution network. The electric motors used in air conditioning systems have a constant torque and inertia, and may therefore be stalled due to voltage drops And after the fault clearing, by dragging high reactive power and a current of 5 or 6 times the rated current, it leads to a continued voltage drop and a slowdown in the voltage recovery process. After a while, the thermal protection devices of the motors can cause significant load losses and subsequently increase the...
Article Electric Power Systems Research ; Volume 81, Issue 7 , July , 2011 , Pages 1507-1513 ; 03787796 (ISSN) ; Ranjbar, A. M ; Feuillet, R ; Sharif University of Technology
Recent system wide disturbances have demonstrated the need for automatic system protection schemes to prevent such cascading disturbances. In this paper, an adaptive under-voltage load shedding scheme using model predictive control is proposed to protect power system against voltage instability. The proposed scheme calculates the criticality of the system based on the measurements of voltage magnitudes and reactive power generations and then in case of voltage instability a model predictive based step-sized load shedding scheme will be triggered. The speed and amount of load shedding steps are adapted to the severity of contingency in the affected region. By devising the grid into the...
Article Energy Conversion and Management ; Volume 50, Issue 6 , 2009 , Pages 1578-1585 ; 01968904 (ISSN) ; Shayanfar, H. A ; Fotuhi Firuzabad, M ; Sharif University of Technology
This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting...
Article IEEE Transactions on Instrumentation and Measurement ; Volume 69, Issue 9 , 2020 , Pages 6613-6620 ; Habibi, M ; Magierowski, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2020
Low-power wireless stand-alone sensors that can operate without any wiring have received significant attention in sensor network applications. These devices harvest environmental energy resources to supply their power and transfer their collected data using wireless RF links. In many instances, the power supplied from the environment is far less than the power required by the sensor device. In this case, the main solution is to accumulate energy on a storage element, and when enough energy is stored, the sensor node is instantaneously activated using an undervoltage lockout (UVLO) circuit. During this short time burst, the sensor performs the required acquisition, transmits the results, and...
Article 2007 Large Engineering Systems Conference on Power Engineering, LESCOPE'07, Montreal, QC, 10 October 2007 through 12 October 2007 ; January , 2007 , Pages 310-315 ; 9781424415830 (ISBN) ; Shayanfar, H. A ; Hosseini, M ; Sharif University of Technology
This paper presents modeling of Series Static Voltage Restorer (SSVR) in load flow calculations for steadystate voltage compensation. An accurate model for SSVR is derived to use in load flow calculations. The rating of this device as well as direction of required reactive power injection to compensate voltage to the desired value (1p.u.) is derived and discussed analytically and mathematically using pahsor diagram method. Since performance of SSVR varies when it reaches to its maximum capacity, modeling of SSVR in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes,...
Dynamic behavior analysis of doubly-fed induction generator wind turbines - The influence of rotor and speed controller parameters, Article International Journal of Electrical Power and Energy Systems ; Volume 32, Issue 5 , June , 2010 , Pages 464-477 ; 01420615 (ISSN) ; Parniani, M ; Sharif University of Technology
This paper analytically investigates the effects of system and controller parameters and operating conditions on the dynamic and transient behavior of wind turbines (WTs) with doubly-fed induction generators (DFIGs) under voltage dips and wind speed fluctuations. Also, it deals with the design considerations regarding rotor and speed controllers. The poorly damped electrical and mechanical modes of the system are identified, and the effects of system parameters, and speed/rotor controllers on these modes are investigated by modal and sensitivity analyses. The results of theoretical studies are verified by time domain simulations. It is found that the dynamic behavior of the DFIG-based WT...
Article International Symposium on Industrial Electronics 2006, ISIE 2006, Montreal, QC, 9 July 2006 through 13 July 2006 ; Volume 3 , 2006 , Pages 2019-2024 ; 1424404975 (ISBN); 9781424404971 (ISBN) ; Amraee, T ; Ranjbar, A. M ; Sharif University of Technology
Under voltage load shedding (UVLS) is one of the most powerful countermeasure and somehow an economical solution to sustain voltage stability especially for double or severe contingencies in power systems. In this paper the concept of dynamic security-constrained OPF is employed to develop a model for optimal UVLS. Considering dynamic voltage security, the presented model attempts to provide sufficient voltage stability margin for post contingency condition. This is done by means of interruption some portion of loads at minimum cost. The voltage stability margin, which is measured as a MW distance to the collapse point, is incorporated into the power flow equations. Although some powerful...