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This paper presents a new power controller for inverter-based renewable power generators, which is based on direct power control of active and reactive power. The controller included fast PLL and ROCOF units in order to function in both grid-connection and islanding operations. The controller's performance was tested by detailed computer simulation of a 2MVA renewable power generator with a DC-link...
This paper investigates how an on-load tap changer (OLTC) can be used to regulate the unbalanced three-phase voltages when single phase unbalanced loads are connected to a radial LV distribution feeder. An overview of current voltage regulation technologies for distribution network is presented. Two voltage regulation strategies are developed to eliminate the effect of the unbalanced single phase...
Over the years, different methods have been used in order to avoid problems with load encroachment, and each method presents its own set of advantages and disadvantages. Regardless of the method used, each relay will have a maximum "loadability limit" that will cause the relay to operate under high load conditions. Therefore, it is important for the relay engineer to understand and take...
Application of local data at receiving node of the system to estimate and control its parameters were considered in the paper. Using Thevenin model some methods were developed, analysed and simulated allowing to estimate and control stability margin and voltage level. The results can be used to construct voltage controller on basis of power electronics.
The paper presents a new pole slipping protection method that combines high efficiency of pole slip detection and sensitivity to many sources of potential pole slipping. To simplify the setup process the adaptive settings are calculated continuously. The new adaptive method utilizes active and reactive power measurements on machine terminals to ascertain that the synchronous machine is committed to...
Decentralized Energy Resources (DER) and especially wind farms became a challenge for protection, automation and control in the grids. Transmission system operators as well as distribution system operators require tests of Loss of Mains and other decoupling protection functions. In some countries certification of these functions is required. The units are equipped with a huge amount of internal protection...
With their increasing number, it is getting important that decentralized and renewable energy sources are supporting the stabilization of the system voltage after short voltage dropouts. Often, in the past, these generators were disconnected during network faults. This is not adequate anymore, as it would lead to a loss of a considerable amount of feed-in power. However, if the generators stay connected,...
In this paper, the impacts of DERs on the designed SPSs are investigated and some solutions based on the progressively developing communication infrastructure of the newly evolving smart grids are proposed to maintain the integrity of the power system in extreme contingencies. A sample system with high penetration of DERs is considered and a SPS is designed for the system. Afterwards the impact of...
Loss-Of-Excitation (LOE) condition of a generator may cause severe damages on both generator and the interconnected systems. This paper analyses the behaviours of different LOE protection schemes, such as R-X, G-B, P-Q and U-I schemes, for a hydro generator, which is connected to an infinite bus. Based on the simulation results, the reliability and stability of existing LOE protection schemes are...
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