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Malawi: Automatic Generation Control System to Help Maintain Electricity Frequency At 50+ or – 1 Hertz


The electricity that Malawians use every day in their homes must be quality power and must meet well-defined parameters for it to be fit for use in everyday work.

This was said by acting Chief Executive Officer (CEO) for Electricity Generation Company (EGENCO), Eng. Dr. Maxon Chitawo on Wednesday at the launch of milestone on the automatic generation control (AGC) — a system that migrates generation control from manual to automation.

It was done in collaboration with Electricity Supply Corporation of Malawi (ESCOM) and was officially launched by Minister of Energy, Ibrahim Matola at Sunbird Mount Soche Hotel in Blantyre.

In his speech, Eng. Chitawo, who before taking up the acting role as CEO was director of operations, said in Malawi, the electricity frequency “must be generated, transmitted and distributed at a frequency of 50+ or -1 Hertz”.

Hertz (Hz) is the standard unit of frequency in the International System of Units (SI) and it is a derived unit based on the second(s), one of the seven base units in the SI standard. The base units, in turn, are constructed from the seven SI defining constants.

Thus Chitawo emphasized that when the frequency is maintained at 50+ or -1 Hertz level, “it means that the power that that is generated and supplied to people is of good quality.

He also said as the world grapples with climate change and energy security challenges, “efforts to build resilient, efficient, and sustainable electricity supply networks have never been more critical”.

“Ensuring a reliable electricity supply should therefore be a priority for every country. The AGC is an important control function within our power control system.

“Its purpose is the tracking of load variations while maintaining system frequency, net tie-line interchanges, and optimal generation levels close to scheduled (or specified) values as I have said earlier.

“To put it simply, the AGC is a system for adjusting the power output of multiple generators at different power plants, in response to changes in the load.”

He stressed an AGC is a commonly used control system in many power systems for balancing of generation with demand and preservation of the tie line power and frequency changes within allowable limits.

In his speech, Minister Matola alluded that there was some elements of competition between the two institutions but he applauded their collaboration to initiate and roll out the all-important automated system.

And on his part, Chitawo said despite having different roles in the value chain of electricity generation, transmission, distribution and supply, technically they all operate one system.

“In other words, the generating machines in EGENCO must speak the same language with the transmission and distribution lines in ESCOM as well the customer’s usage of electricity.

“When there is high demand by the customers, the generating units must be able to respond accordingly and timely so that we maintain the system balance.

“Therefore, the installation of the AGC will help in maintaining that balance so that the machines can automatically adjust the levels to respond to the system demand, maintain a stable power generation, and supply to the customers.

“The AGC is beneficial to both EGENCO and ESCOM — hence our collaboration in the project,” he said, while applauding all engineers and staff in in EGENCO and ESCOM “for the wonderful collaboration in the implementation of the project”.

Representing ESCOM’s Board, George Mazalale said with the commissioning of AGC on the selected four units (two 32.4 megawatt (MW) units at Kapichira Hydro Power Station and another two 31 MW units at Tedzani III to the SCADA system at national control centre (NCC) it is expected to also assist in reducing deemed energy charges as curtailment on variable renewable sources.

And in the long term, the AGC will help Malawi manage power flows on the Interconnector when the energy sector connect to the Southern Africa Power Pool.

Apart from generating power using hydro system, which is a renewable energy, EGENCO also manages solar power plants and as the previous manual system was slow and sometimes prone to human error, the integration of renewable energy greatly challenged the old system — hence AGC’s introduction.