Mitigation of Arc Flash hazard by using protection solution
This paper gives an introduction to the problematic phenomena of arc flashing. For protection engineers important terms and facts in the NFPA 70E standard and the IEEE 1584 standard will be presented. The importance of the fault clearing time will be discussed in detail. Protection schemes which achieve fast fault clearing times for bus faults and feeder faults will be reviewed. In this paper an application will be introduced which is based on the reverse interlocking scheme. Additionally it offers a new solution that achieves a fast fault clearing time for bus faults and close in faults. This is normally the area within a substation, where arc flashing can cause a potential hazard for operators. This application will eliminate the problem of longer fault clearing times for faults close to the bus due to the co-ordination with radial feeders relays. This paper will discuss the necessary settings considerations and will show the limits of this application
"Applications and Advantages for Protection schemes using IEC 61850 Standard"
Modern substations which are being built today use sophisticated microprocessor based relays. These relays have drastically reduced the cost of substations by combining multiple protection elements into one device. Additional enhanced functionality has also eliminated the need for separate devices such as measurement transducers, sequence of event recorders, large point count RTU's (remote terminal units) and, transient fault recorders. Until now complicated control schemes, such as, an auto transfer scheme or a throw over scheme for main-tie-main switchgear, or reverse interlocking bus protection, still required copper wires, auxiliary and lockout relays to achieve high speed reliable functionality. Implementation of the new IEC 61850 (International Electrotechnical Commission) standard will allow this to change
Simulation and control of hybrid renewable energy system connected to the grid
This paper presents a control and simulation of hybrid renewable energy system connected to the grid. The studied system includes a photovoltaic panel, synchronous permanent magnet generator based wind turbine, and a battery for storage energy. The PV array and wind systems are connected to the common DC bus by a boost converter. The battery is connected by a bi-directional DC/DC converter, and then integrated into the AC utility grid via a common DC/AC inverter. In order to extract the maximum energy, a simulation study has been carried out according to the meteorological conditions (wind speed and variable solar irradiance) while maintaining power quality at a satisfactory level. In order to capture the maximum power, a MPPT algorithm is applied for both wind turbine and photovoltaic panel. The modeling and simulation of the whole system has been performed under Matlab/Simulink environment. The obtained results show that the current and the voltage of grid side are sinusoidal and alternative forms, and the power injected to the grid is around the power produced by the hybrid system.