Demand for electricity for both business and domestic use is rising rapidly across Africa as a result of population growth, urbanisation and sustained economic development. Many countries are facing shortfalls in energy generation and so developing widespread, reliable and robust access to electricity is a primary goal for utilities.
There is a growing recognition in many organisations that renewable sources can play a
major part in addressing the generation capacity shortfall at grassroots level. Smaller, local PV and other low carbon schemes allow communities to rapidly access electricity (installation can take less than a year in contrast with major infrastructure development,
which may take up to eight years) and there is growing investment in these installations across Africa.
However, this growth in distributed energy resources (DER) results in more active networks, which are characterised by bi-directional power flow, variable voltage profiles and less predictable loads and fault current levels. This presents utilities with many
challenges as active networks have different dynamics from traditional, passive networks and require different information, planning and management processes to ensure the quality of supply is maintained.
Managing technical and non-technical losses
The rise of renewables and DER presents another major challenge for companies in managing technical and non-technical losses. In any distribution network, there are
inherent technical losses due to the flow of current or energisation of the system.
However, non-technical losses – particularly electricity theft or fraud – are a major problem for companies globally and utilities in Africa are no exception. The Southern Africa Revenue Protection Association (SARPA) estimates illegal connections and tampering equate to around 20% of revenue loss for electricity companies across sub-Saharan Africa.
Electricity theft is more than just a cost to the electricity companies – it impacts everyone. It contributes to higher electricity tariffs, power outages due to overloading and variable
power quality, which can damage appliances connected to the supply. Most seriously, illegal connections can result in unsafe supply and, at worst, electrocution.
One crucial area in managing technical and non-technical losses is improving visibility of the ‘last mile’ of the distribution network. Previously the lower voltage (LV) network has been all but invisible in terms of system monitoring. Utilities were reliant on faults being reported by consumers to help them locate problems, and there was little or no visibility of ‘stress points’ at this level of the network.
Understanding demand profiles at this level (especially unusual or unpredicted spikes) and having clear visibility of power flows and quality across the LV distribution network
enables companies to identify technical and non-technical losses; pinpoint where these are happening and quickly manage or resolve any issues.
The changing face of low voltage monitoring
Historically, the focus for management of LV networks has been maintaining and improving the quality of supply to customers and ensuring the operational efficiency of the networks. This was achieved through power flow monitoring and fault passage measurement on the medium voltage network.
However, the introduction of large amounts of small-scale, embedded generation at LV level increases fault levels and has a major effect on voltage profiles. Utilities need more
data and access to daily energy profiles to improve visibility and help increase flexibility.
Given that peak demand and unregulated usage may need to be met without major reinforcement, it will also be important to prevent overload of the network. As a result, utilities may need to consider temporarily or permanently increasing the ‘electrical
headroom’ on the network.
In terms of effectively managing the LV distribution network and the challenges presented by both electricity losses and renewable technologies, utilities need access to accurate, timely data and actionable information. More sophisticated LV monitoring systems, such as Lucy Electric’s award-winning GridKey system, can help. This world-leading system
measures, communicates and stores real-time data, translating it into actionable information through a suite of analysis tools to help utilities plan to meet these challenges.
The system can be safely retrofitted to LV feeders to include LV power flow monitoring, measurement at the LV side of the transformer (i.e. current, voltage, active and reactive power, voltage, harmonics, flicker, sags, swells, etc.), LV fault passage indication and LV fault location. The system offers class 1 accuracy over 4-720Amp range with minimal cross-feed, plus communications, alarms and reports.
Taking voltage inputs from the busbar, the metrology and communications unit (MCU) has a reporting period, which is adjustable from one minute to 24 hours and can be altered remotely. The metrology units measure the current and voltage inputs and carry out a series of calculations that are then communicated to a central database for analysis. The unit has programmable alarms to alert the operator to maximum and minimum
parameters reached and data can be retrieved from the unit over GPS. The current is measured using Rogowski style current sensors – specifically designed for LV monitoring
– and different types of sensor can be used and mixed, depending upon the system monitoring requirements.
The data the system collects is transmitted to its data centre, where it can be analysed and presented back in highly visible dashboards, which give operators an ‘at a glance’ situational analysis of the LV network. Analysis tools provide daily load profiles and voltage level data to help utilities plan for ‘stress points’ and energy losses in the network and maintain statutory voltage levels.
Focus on the future
Looking ahead, management of distribution networks will have to change to accommodate increasing amounts of small-scale and intermittent generation. This is especially true at LV level where new analytics will be required to provide decision makers with actionable information rather than data. This information will need to be predictive and shareable; and will require clear definition to provide a wider situational awareness of the LV network – essential for utilities to ensure they continue to meet statutory voltage requirements and to help them address the growing issue of electricity theft.
Furthermore, the ability to predict where faults are likely to happen, detect when they do happen and provide information that will allow the fault to be fixed more quickly, will help utilities to maximise any existing asset base; improve quality of service to the electrical consumer; diagnose and solve problems more quickly; and ultimately reduce capital and
ABOUT THE AUTHOR
Tim Spearing is responsible for the product management of the automation business in Lucy Electric. These products range from secondary RTUs to complete SCADA and automation solutions. Tim is a chartered engineer, a member of the IET and a key supporter and contributor to IET Developments in Power System Protection (DPSP), the IET Midlands Power Group in the UK, the UK Smart Grid Forum and EU Smart Grid Task Force.