Ahmed Al-Nadabi

Design a simulation model to estimate the hot spot temperature in power transformers

The aim of this paper is to present a simulation model to predict the thermal behavior of power transformers. The model equations are established to calculate the top oil and hot spot temperatures. A simulation tool is designed to predict a transformer top oil and hot spot temperature based on the transformer manufacturer data and loading. The top oil model equation and hot spot model equation is solved numerically using Euler method and showed good results. In this paper the top oil model and the hot spot model are considered.

Reactive Power Compensation in Oman 400kV Transmission System

The objective of this paper is to present the challenges, methodological approach and possible solutions for the overvoltage issue during the winter light load period in the Main Interconnected Transmission System (MITS) of Oman after introducing the new 400kV system. Load flow studies of the planned MITS in 2016, including representation of other local and GCC interconnection grids, have shown overvoltage issues at the 400kV substations in Oman during winter off-peak demand. These voltage issues can even lead to difficulties in synchronizing the 400kV circuits. Simulation results are presented to define the size and location of a reactive power compensator which can resolve such overvoltage issues. Many options of the reactive power compensation, including fixed and variable means, have been studied and the best option (fixed shunt reactors) is selected.

A review of reactive compensation in the Main Interconnected System of Oman

Overvoltage is a concerning issue among Gulf Cooperation Council (GCC) nations during the winter light load period. This paper presented a review of the recent reactive compensation studies conducted by Oman Electricity Transmission Company (OETC) for the Main Interconnected System (MIS) of the Sultanate of Oman, regarding to its new 400 kV transmission systems. Discussions about challenges and possible solutions were outlined to highlight the unique operating nature of Middle East electrical infrastructures. Simulation results were presented to demonstrate the impact of 400 kV systems on the existing MIS grid. This paper serves as a contrasting example of voltage stability issues encountered by western utilities.

Dynamic assessment of voltage & reactive power control in Oman Transmission System

The paper presents dynamic assessment of voltage and reactive power control in the Main Interconnected Transmission System (MITS) in Oman. Two case studies are considered; namely the MITS with and without temporary diesel generators. Voltage and reactive power control is achieved by optimization process to maximize reactive power margin of generating units to maintain as much as possible reserves on different generators. The optimal power flow technique is used to determine the optimal settings of the control facilities. These include adjustment of generation reactive power injections, transformer tap-changers and switching on/off of controllable shunt capacitors. The objective is to verify that the MITS is able to achieve an adequate steady-state voltage profile and acceptable dynamic performance. Simulation results are presented to show the dynamic performance of the system when it is subjected to a large disturbance such as outage of a generating unit or outage of a transmission circuit.

Impact of a 200 MW concentrated receiver solar power plant on steady-state and transient performances of Oman transmission system

The paper presents steady-state and transient studies to assess the impact of a 200 MW Central Receiver Solar Power Plant (CRSPP) connection on the Main Interconnected Transmission System (MITS) of Oman. The CRSPP consists mainly of a central solar receiver, power tower, thousands of heliostats, molten salt storage tanks, heat exchangers, steam generator, steam turbine, synchronous generator, and step-up transformer. Two proposed locations are considered to connect the CRSPP plant to MITS: Manah 132 kV and Adam 132/33 kV grid stations. The 2015 transmission grid model has been updated to include the simulation of the proposed 200 MW CRSPP using the DIgSILENT PowerFactory professional software. The studies include load flow analysis and short-circuit level calculations in addition to transient responses to three-phase fault and complete CRSPP outage. The results have shown that the connection of the proposed CRSPP plant to the MITS is acceptable.