Standardisation drive to improve reliability
By Francis Uratun
Engineering Research and Planning Team in an effort to improve current power reliability is spearheading the notion of standardisation of all PPL generation, transmission and distribution systems.
This is the way forward for reliability improvement and would involve the review of power stations, transmissions and substation design philosophies and/ or policies.
Network Planning Engineer, Francis Uratun said the standard design procedures were adopted by PPL (ELCOM at that time) and endorsed by the Board in 1992, in line with international standards.
Mr Uratun said this decision was not fully implemented over the years and had affected reliability of electricity supply as currently experienced.
He said because of the lack of standardizing power stations, they often housed a large variety of generators of different manufacture, model and age.
“This leads to multiple stocks of expensive spare parts being held, higher fuel consumption but less power output, and more operation staff training required to familiarise them with the different engines or generators,” he said.
Mr Uratun said the team planned to revitalise the concept of abiding by one single set standard and practice for generation, transmission and distribution, beginning with generation.
He said the team was currently conducting investigations both in major and minor centres to find out the magnitude of the challenges to assist them develop proper guidelines.
“For example, the expansion of PPL’s generating facilities has proceeded in a somewhat ad hoc fashion for many years, resulting in few standard features existing either between power stations or even within one power station,” Mr Uratun pointed out.
“There are also a number of design deficiencies in almost all power stations which create operational problems, compounded by the lack of standardisation.”
He explained that if PPL decided to undertake a program of converting its isolated diesel power stations to automatic operation, essential features of this program would include the need for power station design to be standardised and high voltage feeder systems to have proper protection and monitoring features.
“All new power stations should fully comply with the Standard Design Procedures,” he said.
Mr Uratun said the rating of all generators to be installed must be selected according to the following criteria:
• Each power station should have only three generators installed
• Two generators should be rated at 60% of forecast system peak load in ten years time
• The third generator set should be rated at 40% of forecast system peak load in ten years time
• When justified, a fourth set can be installed and should also be rated at 40% of the forecasted ten year maximum demand
• Whenever possible, all generators within a power station should be of the same make and model.
Mr Uratun said currently most power stations had four or more generating sets of widely different ratings (sizes), which tend to be fairly small in relation to the current system peak load.
He said operators were then required to run each set at a different load and often monitor three sets at a time, which was a problem.
“One operator operating three generators at the same time is very hard and at times when the system is facing problems, the poor operator will be exhausted running form generator to generator to do adjustments just to keep the generators synchronised. That is hard work requiring more operators,” Mr Uratun said.
He also said it would be more fuel efficient and easier from a control viewpoint to have three (maximum of four) sets of similar ratings (sizes), as the maximum number of generator sets running at any time would be two.
“Streamlining in this manner is essential to allow an effective automatic control system,” he explained.
Mr Uratun said maintenance staff and operators also needed training on a large variety of engines, generators, controls and switchboards.
He said standardisation on generators and models would greatly reduce such problems and inefficiencies.