wind energy
Featured image: Stock

Since the African Development Bank (AfDB) is no longer funding coal-fired power generation and several South African banks are announcing their decision to follow suit, investment has turned its focus to renewable energy, which presents grid management challenges.

This article first appeared in ESI Africa Issue 4-2019.
Read the full digimag here or subscribe to receive a print copy here

Faced with an increasingly fast-paced shift toward more affordable, sustainable and green energy, the global electricity industry, specifically across Africa, is seeing how the decarbonisation agenda is shaping both policy and industry investment. In March 2019, the AfDB doubled its commitment to climate finance for 2020-2025 to $25 billion, launching a Green Baseload Facility to provide concessional finance in support of reliable and affordable renewable energy projects.

In quick succession, the Kenyan Government followed suit announcing ambitious plans to increase investment in solar energy projects; while the UN Green Climate Fund is also mobilising funding of $51.7 million for solar mini-grids in Mali, with a host of smaller projects reported.

Spurred on by this investment, renewable and distributed energy resources (DER) are now becoming an increasing part of the energy generation mix. This is evident across Africa where there is great potential for high volumes of photovoltaic, wind or geothermal energy generation, depending upon the location.

It is this escalation of distributed energy generation growth that raises the most concern for the industry, as it results in network complexity and a variety of challenges for grid management. In this regard, it is inevitable for utilities to accommodate temporary constraints on their networks, a diverse range of generation and rapid clustering, such as rooftop solar PV installations.

Overcoming DER connection challenges

One of the first challenges of the growth in renewables is connecting generation capacity to local infrastructure. Most DER installations such as solar and wind require a 36kV connection and are often in remote and inaccessible locations. In 2017, Lucy Electric launched the Aegis36 Ring Main Unit (RMU), which is ideally suited to facilitating the connection of renewable sources. The units are automation-ready, with optional integrated remote terminal units for remote operation and control to support the active network management required with DER.

Its uniquely compact design means it has one of the smallest footprints of any 36kV RMUs on the market, making it easy to accommodate on small sites. With virtually maintenance-free operation, the unit is suitable for use in remote and inaccessible areas.

Smart alternatives to network upgrades

The major challenge facing utilities in accommodating the growth in energy usage and the diversity of the energy sources is network management. In a traditionally passive grid infrastructure, this would usually mean substantial investments, which would be underutilised most of the time.

So what are the alternatives for network operators? Many companies are undertaking the move to more dynamic ways of operation and smarter alternatives to network upgrades. They are supplementing asset replacement and network reinforcement by increasing the agility of networks and enabling customers to deliver additional flexibility when required.

Utilities are employing information and communications technology to deliver solutions that make the best use of network flexibility, demand side response, storage and renewable generation at all network levels.

The route to a more flexible network

With increased penetration of renewables and other DER, the development of new control room applications for system operators and DER operators has evolved. Utilities now have to manage demand, and the supply from various generation sources, at a distribution level in real time. Demand may increase, and more or different energy sources may become available on a variable basis.

Equally, they may not be available because the network is constrained and cannot support any more generation. The distribution network has to be managed in a similar way to the transmission network. Collectively these applications are termed Active Network Management (ANM) or in some markets Distributed Energy Resource Management Systems (DERMS).

The use of Active Network Management techniques can increase the hosting capacity. It can also assist in adding DER to networks that would otherwise be considered ‘full’ without running the risk of exceeding operational limits.

The conventional approaches to integration of DER have been to plan for the maximum secure hosting capacity. This leaves reserve or latent capacity in the network for the majority of the time. To release this latent capacity, ANM systems can be used to monitor the real-time capacity of the grid and reduce distributed generation output only when the grid is actually under stress.

Here are two constraint management schemes that help manage this capacity:

1. Timed Connections, which help reduce the level of upstream reinforcement required to facilitate new connections; and

2. Centralised ANM, which uses RTUs to actively manage the distributed generation and the storage without interfering with the operation of the utility network.

These techniques for integration of DER are adding value through facilitating the growth of renewable generation, and doing this without network reinforcement, thus reducing the connection costs. Integration of DER is extracting value because it is making available the latent capacity in the network. However, commercial arrangements need to be in place to manage the enforced intermittent nature of the DER under an ANM scheme. In addition, there may be a risk of nuisance tripping and potential impact on power quality levels of the network. ESI

About the company

Lucy Electric is a leader in secondary power distribution solutions and specialises in high-performance medium voltage switchgear for utility, industrial and commercial applications.

www.lucyelectric.com | @Lucyelectric