Nasser G.A. Hemdan

Distributed generation location and capacity effect on voltage stability of distribution networks

Analysis of the effect of distributed generation (DG) capacity and location on voltage stability enhancement of distribution networks is presented in this paper. The analysis is performed using a steady state voltage stability index which can be evaluated at each node of the distribution system. Different optimal capacities and locations are used to check this effect. The location of DG has the main effect on the system voltage stability. Voltage stability should be taken into account as one of the objectives of DG optimal allocation techniques. The analysis is conducted on a 69 node distribution system.

Effect of integration of Distributed Wind Generation into a real MV distribution network: A case study using measured wind data and simulated load profiles

The interest in the integration of distributed generation into distribution systems has been increased in different countries all over the world as economic and environmental factors drive new technologies to be more efficient and less polluting than their earlier counterparts. As the penetration level of DG increases, the distribution system performance has to be analyzed in details. This work investigates the effects of Distributed Wind Generation (DWG) on voltage ranges, voltage profiles, and system MWh losses of a real MV distribution network. The availability to integrate a new wind mill into the system that already contains three wind mills is examined with respect to the technical conditions for generation connection to the MV networks introduced by German Energy and Water Federation. In the simulation, we used a one year measured wind data and simulated load profiles of the households which are connected to the LV side at each MV substation.

Allocation of decentralized generators in distribution networks for enhancing normal operation loadability

This work presents a new approach for placement and dispersing of Decentralized Generation (DG) power in medium voltage distribution networks based on Continuation Power Flow (CPF) method. The main objectives of the proposed method are to maximize the Normal Operation Loadability (NOL) (i.e. the maximum loading which can be supplied by the power system while the voltages at all nodes are kept within the limits) and to obtain more benefits from the same amount of DG power. The results obtained with the proposed methodology for a 85 node distribution network demonstrate its applicability.

Fault matrix based protection coordination in low voltage DC systems

Protection coordination represents one of the main challenges in the developing process of reliable and efficient DC systems. In the current research, a new protection coordination scheme based on fault matrix concept was developed. A testbed was established at Institute of High Voltage Engineering and Electrical Power Systems (elenia) laboratory, Braunschweig University of Technology to verify the operation of the proposed protection concept. Moreover, simulations using PSCAD/EMTDC were conducted. The new protection concept was implemented on 24 V DC systems. The simulation results showed that the proposed scheme is able reliably to detect the fault and isolate only the faulty part in the system.

Operation and protection of 380V DC distribution systems

The demand of a reliable, sustainable, and resilient electrical energy grid motivates the integration of renewable energy-based resources based on different technologies. New network structures are essential in approaching these goals. Low and medium voltage DC grids could introduce a key answer in this context. In this paper, the operation of 380 V DC distribution grids for different applications is reviewed and evaluated. Furthermore, a new efficient protection scheme based on credit point concept was proposed to detect, allocate and isolate faults in such DC grids. The new technique was designed in order to be implemented in the laboratory. The proposed protection scheme was tested using PSCAD software based on radial DC distribution system. The concept for experimental implementation was established and will be presented. The new approach has been found to be robust and effective in detecting, allocating, and isolating faults in DC grids.

Time Series Analysis of Rural Distribution Grids in the Presence of HTS Cables and Intermittent Renewable Resources

The energy transition in Germany leads to an increase of the renewable energy resources integration especially as small units into the distribution level. Therefore, different new technologies such as superconductivity will play an important role in the future of such grids. In the current work time series implications of interconnection of high temperature superconducting (HTS) cables into MV rural distribution grids with high penetration of renewable energy based resources were investigated. Two different scenarios were technically evaluated. The voltage quality, reserve capacity, and energy loss of the grid were analyzed using HTS and conventional lines and cables.

Switching state optimization influences on active distribution systems operation

In the current work the implications of distribution networks reconfiguration on the system operation were investigated. Different technical issues such as voltage profiles, line loading, and On-Load Tap Changer (OLTC) were tested through the switching state optimization of the network. The simulations were conducted based on load and renewable energy based generation profiles. Different day types in different seasons were simulated. A comparison between switching optimization of the network one time per day and hourly switching was also performed. The results show that the voltage profiles will be improved. Moreover, the bottlenecks in the lines can be released. Optimization of the switching state for one time per day can be better than switching in an hourly scheme.

Dynamic virtual reactive power plant in active distribution networks

In recent years the penetration of renewable energy based resources has increased significantly. This development has a high impact on the network control behavior. The renewable energy sources can be used to contribute to the ancillary services for enhancing the quality of service and the resilience of the power system. In the current study, an approach of applying a reactive power management using renewable energy based decentralized generators is introduced. A virtual reactive power plant algorithm was developed in order to perform reactive power balancing. The proposed approach was implemented in a MV distribution network simulation. The impacts off high reactive power infeed on the network shell be investigated and general questions on reactive power pricing are discussed.