Abstract:
The Port of Mombasa handles cargo from container ships, cruise ships, conventional ships, roll on roll off and vehicle ships, military, oil and product ships. At berth the main engine is switched off and the auxiliary generators take control of all the power generation on board. Auxiliary engines on ships use heavy fuels which result in release of pollutants such as greenhouse gases in addition to being a source of noise and vibrations. Ship-to-shore power has been identified as one technology to reduce emissions by at least 90% in harbour areas. To implement shore power technology for commercial ships in Kenya, detailed analysis of the existing power system is required to ensure that the additional load can be connected to the grid without resulting in voltage collapse. This study applied induction motor load aggregation (implemented in MATLAB/SIMULINK) to develop a composite load model for berthed ships. The coast 132kV power grid was modelled, with transmission lines represented as pi networks, substation loads as static PQ loads and generating stations as PV generators. Load flow analyses was then completed on the grid and load model using MATLAB/PSAT. Continuation power flow was applied to establish loadability limits using PV curves. The results showed that it is possible to connect the additional load without losing voltage stability. The lowest voltages experienced were at the Mtito and Voi buses with a line voltage of 0.93p.u. Installation of appropriate static VAR compensation at Mtito was found to be an adequate mitigation measure. Bus voltage was observed to rise to 1p.u at Mtito and 0.97p.u at Voi on installation of VAR compensation.