The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, a simple and effective strategy is proposed for the coordination of protective devices in typical radial distribution networks embedding distributed generation units. The proposed strategy benefits from microprocessor-based reclosers and directional elements for feeder relays, and addresses the issues of blinding of protection, false tripping, recloserfuse and fuse-fuse miscoordination,...
Early detection of faults in stator winding is crucial for reliable and economical operation of induction motors in industries. Whereas major winding faults can be easily identified from supply current magnitude, minor faults involving less than 5% of turns are not readily discernible. The present work documents experimental results for monitoring of minor short circuit faults in stator windings of...
This paper handles two main areas of significant interest concerning the use of SVCs in transmission systems: (1) The operational benefits of SVC support during network contingencies (2) The reliability of SVCs in general and at contingency events in particular At transmission level SVCs are installed to act as insurance, supporting the system during recovery from severe contingencies. It is therefore...
This paper provides a novel view for the performance evaluation of protective relays. The paper starts with a Gaussian model for the protective relay setting to describe the effective zone of protection by considering the measurement errors, and introduces the performance index “protectability” for the protective relays. Protectability is defined including the correct trip probability (CTP) and no...
Current grid codes require the fault ride-through capability of modern wind turbines. During grid faults the reactive current control of the wind turbines should be used to support the grid voltage. With modern protection devices the fault durations are normally in a range of some hundred milliseconds or less. However this time window may be decisive for the stability of the conventional generators...
The rapid increase in installed distributed generation (DG) has led to concerns about the impact on the proper operation of the protection system. In particular, the limited fault current capability of inverter interfaced distributed generation (IIDG) could lead to malfunctioning of the distribution network protection system which largely relies on overcurrent based protection techniques. The absence...
This paper investigates methods for DC fault current interruption in high-power DC networks. It is shown that mechanical DC circuit breakers could only offer adequate protection if supplemented with fault current limiters. A simple electronic switch (IGBT or GTO) is suitable as a DC circuit breaker but the component sizing crucially depends on the speed of signal processing circuits. It is likely...
Using bulk energy storage systems such as pumped-hydro electric storage (PHES) and compressed-air energy storage (CAES) with wind power plants offers advantages. They are well-proven technologies and more economical compared to batteries. Being synchronous machines, apart from the ability to regulate wind farm real power output, they can also be used to provide reactive power to support wind farms,...
The failure of several transmission capacitor banks prompted The United Illuminating Company to perform an engineering study to evaluate the transient recovery voltage capabilities of existing 123-kV, oil-filled capacitor bank circuit breakers at the East Shore 115-kV substation. The study determined if the transient recovery voltage capability of existing bus and capacitor bank circuit breakers is...
Microgrids can be viewed as a group of Distributed Generation (DG) units with the capability of operating connected or isolated from the main grid. Most of the work conducted in the area of microgrids focused on developing new control schemes that can maintain the voltage and frequency within standard limits during grid connected and islanded mode of operation. An issue of equal importance is the...
Wind energy is the fastest growing source of renewable energy in the power industry and it will continue to grow worldwide as many countries are developing plans for its future development. For power system operators, this increasing contribution of wind energy to the grid poses new challenges that need to be addressed in order to ensure the reliability and security of the electric power grid. One...
The instrument transformer is the necessary equipment which connects the primary power system and PMU. Therefore, the measurement accuracy of PMU is directly affected by the transfer accuracy and the transient response of instrument transformer. In this paper, the dynamic signal models are abstracted from the phenomena of practical power systems. Under such kinds of dynamic signal models, the impact...
This paper identifies and quantifies the unique characteristics of current-limiting fuse operation as seen in the current and voltage waveforms recorded at a monitoring station located upstream from the fault. Characteristics that can be used to identify current-limiting fuse operations by visual inspection are described. More characteristics are extracted using signal processing methods. These characteristics...
Wind generation is evolving from single wind turbines to wind power plants with an installed capacity of tens of megawatts. Therefore, wind turbines are also coupled to the transmission grid instead of the distribution grid. Problems arise during grid faults as the behaviour of wind turbines equipped with doubly-fed induction generators differs fundamentally from traditional synchronous generators...
While one of the strongest points in a power system is the substation, it still contains what can be described as weak points or points of failure that could lead to major outages. Present paper examines the impact of Superconducting Fault Current Limiter (SFCL) on the transmission substation reliability. To this end, potential application of a SFCL in a practical 138 kV transmission grid is studied...
This paper presents a single-ended traveling wave based fault location method for power transmission systems where overhead lines are combined with underground cables. Bewley diagrams are used to determine the traveling wave patterns. The proposed method utilizes Discrete Wavelet Transform (DWT) to extract the transient information from the recorded voltage signals. The squares of the wavelet transform...
Changes to the power system, especially the installation of new generation sources and new operating conditions, result in higher fault currents. Circuit breakers, which are previously designed and coordinated for the power systems before the appearances of new generation sources and new operating conditions, may have inadequate fault current interruption capability. This paper discusses those operating...
Nowadays, most substations are equipped with Intelligent Electronic Devices (IEDs) performing data collection. With the advancement of measurement techniques and growing availability of information captured by newly emerged IEDs such as Phasor Measurement Units (PMUs), it is imperative to integrate the various data sources with traditional Supervisory Control and Data Acquisition (SCADA)/Energy Management...
Hitherto, the voltage stability of the Long Island Power Authority (LIPA) system has been evaluated utilizing steady-state power flow programs. However, time domain simulations of LIPA system demonstrated significant differences in post-disturbance voltage recovery of transmission system voltages between models with static and complex load compositions. This is mainly due to the predominant residential...
Based on power electronic converting current devices which can be controlled quickly, VSC-HVDC system can regulate active power, reactive power, DC voltage, and line voltage flexibly. Different regulation strategies have different influences on the power system stability. A worse regulation strategiy may lead to sharp fluctuation of electrical measurements and longer regulation time, which is harmful...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.