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the rapidly increasing share of wind power in the electrical power system is both concerning and challenging for the system operators. This leads to stringent requirements for the connection and operation of Wind Power Plants (WPPs) and respectively Wind Turbines (WTs). Taking these and other challenges into account, the Siemens Wind Power (SWP) 3.X MW variable-speed direct-drive WT series or D3 platform (SWT-3.0 MW, SWT-3.2 MW and SWT-3.4 MW) employ direct-drive technology that reduces the components' wear and tear; thus improving performance, reliability and maintainability. Furthermore, for the very purpose of grid assessment and system studies, SWP has developed and provides dynamic electrical simulation models for the D3 platform in various power system simulation tools, such as DIgSILENT PowerFactory, Siemens PTI PSS®E, PSCAD, EMTP-RV and PSS®NETOMAC. The dynamic simulation models are validated against fault-ride through tests and other specific purpose measurements in order to ensure accurate model performance. This paper presents measurements and model validations of SWT-3.2 MW WT. Measurement results are scalable and the results and performance can be easily extended to other Wind Turbines of the D3 platform including SWT-3.0 MW and SWT-3.4 MW as they all share a common converter hardware and software core. The presented results as well as other benchmarking results show relatively good match between measured and simulated results. [ABSTRACT FROM AUTHOR]

The European Transmission System Operators specify grid codes to ensure a safe and reliable operation of the electrical power system. Wind Power Plants have to comply with specific requirements prior installation and operation but some of the requirements are open to interpretation due to a lack of specificity. This paper focuses on the rise time requirement specified in European grid codes where different interpretations leave an open debate whether the requirement can be fulfilled or not. The definitions present in European grid codes are evaluated in this paper with the following methodology: first the uncertainties in some Transmission System Operators' definitions of rise time, step response time and settling time are presented; then a comparative analysis is performed among calculation methods, such as instantaneous reactive current in alpha-beta reference frame, direct and quadrature reference frame, and Root Mean Square of the positive sequence component. All the calculations are first performed on an ideal data test case, and thereafter on a real site data test case. Finally, the reactive current rise time is computed from all test cases with all calculation methods, and the rise times computed with different methods are then compared. The comparison shows that the rise time of the reactive current is significantly affected by the calculation methods: this effect in some cases can make the difference between fulfilling the requirement or not. As a result of that, both manufacturers and Transmission System Operators can draw different conclusions about a turbine's compliancy with the grid code. [ABSTRACT FROM AUTHOR]

This paper presents a detailed analysis for determining the impact of adding single phase photovoltaic (PV) systems in residential power distribution networks. This study highlights the issues arising due to the increase in fault levels in the network caused by the contribution from PV generators. A typical power distribution network for a suburban area has been modeled in PSCAD and the changes in fault current magnitude with the incremental addition of PV system has been studied. From this analysis it is found that PV generators can contribute fault current of considerable magnitude and thereby has an appreciable impact on the protection system if the PV penetration level is high. [ABSTRACT FROM PUBLISHER]

Garments respond differently to four types of arc exposures. Moisture in arc exposed garments can alter their appearance in ways not typically observed in standardized arc flash testing such as ASTM F1959, IEC 61482-1-1, IEC 61482-1-2 or ASTM F2621. Color change commonly seen in garments exposed to standard tests do not occur as expected when garments are moist. This information may be useful in accident investigation and hazard assessment. The four types of arc exposures described herein are: Radiated Arc, Ejected Arc, Arc-in-a-box, and a “Tracking” Arc. Two of these arc exposures can be described as plasma-rich and the other two are only circumstantially plasma-rich depending on equipment configuration, duration, voltage, and fault current level. New methods to reduce arc hazards, such as blankets meeting ASTM F2676 and shields meeting ASTM F2522 and how they relate to potential arc exposures will also be discussed. [ABSTRACT FROM PUBLISHER]

The paper discusses design considerations of wind powered generating plants that require knowledge of the fault current contribution of the generators. To provide context, the paper includes brief summary of typical design of the electrical collection and interconnect systems of wind power plants. The impact of fault current contribution on equipment selection is discussed. Common protective relaying practices are discussed and the impacts of fault contributions on setting and selectivity of protective relaying systems are discussed. [ABSTRACT FROM PUBLISHER]

Full converter wind turbines respond differently than directly-connected machines to short circuits. In distinction with directly-connected machines, full-converter wind turbines have a controlled response to system short circuits. Consequently, they do not behave quite like a voltage behind a reactance, as conventional machines do. Also, they do not have a sequence representation in the negative and zero sequences, except as very large equivalent impedances. Modeling of these wind turbines may require modification of existing short circuit programs, which are based on the characteristics of synchronous machines, but the converters can be analyzed in similar manner. [ABSTRACT FROM PUBLISHER]

Device switching times and switching energy losses are required over a wide range of practical working conditions for successful design of insulated gate bipolar transistor (IGBT) based power converters. This paper presents a cost-effective experimental setup using a co-axial current transformer for measurement of IGBT switching characteristics and switching energy loss. Measurements are carried out on a 50A, 1200V IGBT (SKM50GB123D) for different values of gate resistance, device current and junction temperature. These measurements augment the technical data available in the device datasheet.Short circuit transients are also investigated experimentally under hard switched fault as well as fault under load conditions. [ABSTRACT FROM PUBLISHER]

In the case of a fault on electric power system line even basic frequency component of the fault current has rather complex form consisting of constant amplitude member and members with amplitudes attenuated with different time constants. Taking into account that there is a possibility to eliminate DC and harmonic components in electric signals during a fault in acceptable short time period, it was shown here that the rest of the signal can be used for (fast) line impedance calculation with acceptable accuracy. Calculations and testing based on here presented approach with real generator parameters and for all kinds of faults show that error in resulting impedance value was always less then 3%, qualifying the method as acceptable for technical applications. Method of faulted line impedance calculation was referred. [ABSTRACT FROM PUBLISHER]

Along with the development and construction of smart grid and smart substation, the research on the electronic current transformer develops deeply. In order to achieve the measuring requirements of high accuracy and broad range, a new design of combined electronic transformer is proposed in this paper based on the analysis of current technology; the waveform smooth algorithm is adopted to solve the skipping problem which may occur at the time of data switch. At the end, MATLAB Simulations verify the feasibility of the algorithm. This paper will be helpful in the design of combined electronic current transformer. [ABSTRACT FROM PUBLISHER]

This paper propose a new decaying DC component Estimation algorithm for digital relaying. Fault currents tend to include a DC decaying component. This component decreases the accuracy and speed of the protection relay operation. The proposed algorithm can estimate and eliminate the DC decaying component from fault current signals after one cycle from the fault instant. Also, it can be applied to a conventional discrete Fourier transform to calculate phasor quantities of fault currents in a digital protection relay. In the proposed algorithm, the DC decaying magnitude and time constant are estimated exactly by integrating fault currents during one cycle. The DC decaying component is eliminated by subtracting the DC value at each sampling instant. To verify the performance of the proposed algorithm, we performed a DC component estimation test and distance protection test using PSCAD/EMTDC. The results of the PSCAD/EMTDC simulation showed that the proposed algorithm can estimate DC components exactly from fault currents and can be applied to digital protection relays for phasor extraction [ABSTRACT FROM PUBLISHER]

Power system operators deal with the fault current problems seriously, because the large scale fault current not only cause many side effects to the facilities of power system but also lead to severe problems such as blackout. This paper deals with structural analysis and 3-phase fault current stability of the future Seoul metropolitan power system in Korea. Simulation composition and analysis were performed with the 4th Korea Electric & Power Cooperation (KEPCO) power supply planning data using PSS/e. Through the results of simulation, future Seoul metropolitan system has a problem, enormous fault current, which exceeds circuit breaker (CB) rate. This fault current can cause critical damage to power system. To resolve this problem, the algorithm for application of Voltage Sourced Converter Back-to-Back High Voltage Direct Current (VSC BTB HVDC) is being proposed. In the case study, this paper shows most suitable location for solving fault current problem in Seoul metropolitan area. [ABSTRACT FROM PUBLISHER]

Recent pressure relief tests on polymeric-housed arresters for use on series capacitor bank varistors have been carried out with successful results. The increased Mvar rating within a single segment platform does significantly increase the prospective capacitor fault current discharge and energy to values beyond what has been previously tested for Hydro-Quebec series capacitor compensation installations. Tests performed showed that the proposed arresters were fully adequate to withstand these increased thermal and mechanical stresses. Tests have also shown that the capacitor discharge current and frequency can induce significant currents and voltages in laboratory control, protection and measuring wiring systems. Care regarding the test set-up layout, measurement and control techniques shall be taken to avoid or to minimize the induced currents and voltages. This paper gives a summary of the results obtained and describes the mitigation actions taken for reducing such induced currents and voltages to an acceptable level. [ABSTRACT FROM PUBLISHER]

The overall design of electrical supply systems, which adopts UPS, should be developed with more accuracy than conventional systems, including quality requirements. Thereby, transient conditions in electrical power supply must be carefully investigated, to find out the most severe operating conditions that may stress the UPS components, thus increasing the probability of supply failure. This analysis has a strong strategic importance in preventing dangerous situations and it is necessary in order to correctly size all the protection devices comprised on critical electrical systems. [ABSTRACT FROM PUBLISHER]

A neutral beam injection system with pulse-type ion source was developed in Korea Atomic Energy research Institute for the Korea Superconducting Tokamak Advanced Research (KSTAR). Design requirements for the ion source were a 120 kV, 70 A ion beam with a 300 s pulse-on and 30 min. pulse-off periods. For the operation of this ion source, an acceleration power supply with the DC output ratings of 120 kV, 70 A is used. During the pulse-on periods, the maximum input current of a 22.9 kV ac lines for the acceleration power supply is higher than 200 A and the pulse-off periods, current is nearly 0 A with the main circuit breaker normally on condition. In the power distribution system, the sensing level of the fault current is higher than 200 A all the time, so in the non-operating periods of the ion source, the sensing level of the fault current is too high to accomplish a good protection sensitivity. In this paper, we propose a protection system with the variable sensing levels of the fault currents, that is, the sensing levels of the fault currents are varies with pulse-on and pulse-off periods. [ABSTRACT FROM PUBLISHER]