Why power grid collapse-measures to contain it

These two fundamental changes in operation of the Nigerian power grid results in the transmission of power over long distances. This makes the power grid very dependent on the transmission system to deliver power to the load centres. It also results in increased reactive power losses when transmission lines trip.

Using a basic power system with the remote generators supplying a significant amount of power (Ps) over a considerable distance to the remote load centre to illustrate, we find that the load is comprised of resistive load and motor load. During a voltage dip, resistive load current will decrease and help limit the need for local reactive support.

Motor loads are essentially constant kVA devices. The lower the voltage, the more current they draw, increasing the need for local reactive (VAr) support. Power systems loads consist of both resistive loads as well as reactive motor loads. During hot weather, however, air conditioning motor loads comprise a large portion of total load, thereby making the system more susceptible to voltage collapse.

With reference to the frequency of blackouts from system collapses in Nigeria, It is possible that demand for reactive power was unusually high because of a large volume of long-distance transmissions streaming through the southern states to Northern states, more than needed to import power to meet local demand. But the supply of reactive power is very often low because some generating plants are often out of service and, possibly, because other plants were not producing enough of it.”

Suggested solutions

Because reactive power does not travel very far and it is usually necessary to produce it close to the location where it is needed. A power generation source close to the location of the need is in a much better position to provide reactive power compared to one that is located far from the location of need. Reactive power supplies are closely tied to the ability to deliver real or active power.

It is in the light of the above explanation, that we consider the recent completion and commissioning of the Geregu II Power plant as a progressive development that would appropriately contribute towards supplying the needed reactive power to mitigate tendencies for transmission and distribution grid system failures as well as ensure power supply reliability especially to Abuja and its environs.

There is therefore a compelling need to encourage investors to build more power generating plants especially from the non- fossil fuel based systems as a mix derived from; small and medium capacity hydro power plants ( especially from waterfall sources and perennial rivers), biomass, thermal solar, waste-to-power and geothermal power plants within the middle belt and Northern states of the country using most modern modular technologies requiring minimal capital such that would encourage investors to build these plants and support efforts towards increasing the quantum of reactive power supply and further guarantee overall national grid stability.

Government should provide incentives that will encourage investors to invest in these renewable areas of power development in order to equilibrate the demand for reactive power and ensure power grid stability.

In order to effectively encourage investors wishing to take on power infrastructure development in the areas enumerated above, the ministry of power is advised to look into the possibility of developing a compendium of renewable energy power generation resources in order to provide adequate information and available technology guide for intending investors.

As part of interim measure to stem the tide of grid system collapses, the ministry of power should recognise that power grid stability can only be guaranteed through investment in technology and therefore give serious consideration towards deploying smart grids and employing the services of competent consultants to undertake the relevant studies needed for effective deployment of digital smart grids which are most effective for stabilising power grids where renewable mix power sources are to be grid connected.

Digital smart grids will self monitor and self heal, minimising costly outages by diagnosing problems electronically and re-routing power around them. The report of the consultants should also include synchronised phasor measurements (synchrophasors) which provide real-time measurement of electrical quantities from across a power system.

Applications of synchrophasor measurements include system model validation, determining stability margins, maximising stable system loading, islanding detection, system-wide disturbance recording, and visualization of dynamic system response. These systems will not listen to witches and wizards in bringing to an end the incidence of frequent grid system collapse in Nigeria.

Goody Duru-Oguzie (Multidisciplinary consultant on energy, power and environment) principal consultant/CEO, Pow Tech group Ltd)