Omar H. Abdalla

Development of a digital model for Oman electrical transmission main grid

This paper describes the development of a digital computer model representing the main electric transmission system in Oman. A commercially available DIgSILENT power system computation package is employed. A brief description of system is given, which includes generating units, transformers, transmission lines and loads. The system is connected with a number of internal industrial plants to exchange electric power in addition to the interconnection between Oman and UAE. The model is used to perform computer studies such as load flows, short circuit analysis, stability, transient responses, etc. The simulation results are used for evaluating system performance and strategic planning purposes. Sample results are presented to show the capabilities of developed model.

Performance of Oman transmission system with the 400kV Gulf Cooperation Council electricity interconnection

The paper describes the static and dynamic performances of the main transmission system of Oman with the 400kV Gulf Cooperation Council (GCC) electricity interconnection between Oman and Abu Dhabi. A detailed model of the transmission system of Oman is obtained to simulate the steady-state and dynamic system performances using the DIgSILENT software. The model includes simulation of the generating units at power plants with their turbines, speed governors, exciters and voltage regulators. The UAE system is represented by an external source. Simulation results are presented to show the feasibility of successful operation with exchange of up to 400MW between Oman and UAE in either direction in 2014. The results include line and transformer loadings, voltage profiles, fault currents, and dynamic system responses to tripping the 400kV interconnector.

Performance of Oman transmission system with distributed generation

The paper presents simulation studies of installing distributed generation (DG) at a number of grid stations in the main transmission system of Oman. The diesel-engine driven generator units are required on a temporary basis to aid in meeting the peak demand. A digital model is developed to simulate the system including power plants, transmission system, loads and the proposed DG. The simulation studies are performed by using the DIgSILENT software package. The objective of the studies is to demonstrate effects of the DG in improving system performance in terms of voltage profile, line and transformer loadings, and transmission losses. The results include comparison of the contribution of individual generation at each site and the case with all proposed distributed generators installed.

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.

Small-disturbance stability of Oman/UAE interconnected system

This paper presents small-disturbance stability studies of the interconnected power systems of the Sultanate of Oman and the State of the United Arab Emirates. The two systems are interconnected through the existing 220 kV double circuit transmission line between Oman and Abu Dhabi leading to a rather longitudinal structure power system. The objective of the paper is to assess the inter-area oscillation damping of this interconnected system during small amplitude disturbances by using eigenvalue analysis. A detailed model of the interconnected system is obtained including representation of generators, prime movers, speed governors, exciters, automatic voltage regulators, transmission lines, transformers, compensators and loads. The system eigenvalues are calculated at various operating scenarios, including peak and minimum loading conditions with zero and maximum power exchanges in both directions and also during N and N-1 conditions. The results have shown that both systems have adequate damping before being interconnected. After interconnection, the eigenvalues profile indicates that the system will remain stable and satisfactorily damped for the considered power exchanges.

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.