MICROGRID CLUSTERS FOR AFRICA'S ELECTRICITY

By Lewis Waswa Junior Engineer Centre for Renewable & Sustainable Energy Studies 

ENERGYCENTRAL - What is the current energy landscape?

Quick Facts

• About 600 million people in sub-Saharan Africa have no access to any form of electricity. This is approximately 50% of the total SSA population. About 70% of this population live in rural areas. As such, rural access to electricity is constrained - a factor that has led to gross stagnation in development.
• A substantial proportion of the SSA population live under the grid due to high costs of electrification passed down to the consumers.
• Over 25% of the businesses are making losses according to this study. These losses could go up to 70% of the total sales. As of 2018, the access to electricity in rural areas, in SSA region stood at 31.5%. An analysis of the East Africa's rural access to electricity from 2014 to 2018 is illustrated in the chart below.
• This paper looks at the low levels of electricity supply in SSA, its causes, implications and possible remedies.
• A large number of SSA utilities are still vertically structured and are mostly government monopolies. The performance of these entities has been underwhelming. A classical example is Eskom which has been under pressure to supply the rising need for reliable power in South Africa.
• Energy regulators are less equipped to control the markets which have been dominated by these monopolies. This means that these entities are inadequately equipped to manage the changing markets due to among other reasons, poor coordination and political control of the energy sector. An energy regulatory index report on 15 African countries explores the performance of a number of regulators in Africa and classifies the finding on a comparative scale with international best practices. The following figures summarizes the findings obtained in terms of energy sector conformance to the international best practices. 

• There is a concerted effort to consistently fund under-performing monopolies while consistently suppressing the disruption from the renewables. Several indicators in the recent policy changes in Kenya point to an effort by the government to stop PV adoption before it peaks. This report by Climate Scorecard reiterates the fact that state monopoly in South Africa is a hindrance to renewables. 

How can utilities assist in the universal energy access transition? 

Numerous suggestions have been written to provide guidance to the policy makers involved in the development and allocation of energy resources in different parts of the continent. These solutions have bordered on improvement of infrastructure in terms of transmission and distribution, changes in business models, use of renewable energy resources among others. 

In this article, we argue that it may be possible for the utility business to get into renewable energy and deploy mini-grids and micro-grids using a clustered approach. It is believed that the African energy market shall be served mostly by the mini and micro-grids, something that is already happening if the statistics is anything to go by. 

The national utilities cannot therefore stop playing a role in this business for various reasons: 

1. They are bankrolled by the exchequer and therefore they have the financial ability to carry out these projects. Access to electricity is an important milestone in community development and these utilities are supposed to play an equalization role for all regions in a country.
2. The energy sector is a critical part of a nation in terms of development and to some extend, security. As such, a substantial part of the market needs to be controlled and regulated without constraining the aspect of free market.
3. The declining costs of PV, ESS as well as other renewable energy resources is likely to alter the roles played by the grid completely. The SSA market has not peaked and this can be seen from the number of solar home systems (SHS) companies that are investing in this market and the abnormal profits that are made. With a proper business model and the resources available for them, it is possible to develop a working framework that seamlessly merges the role of these entities and the private sector.
4. Regulatory curtailment of renewable energy resources, without supply side reliability improvement, is likely to lead to stagnation of electricity access levels or will spur a mass migration to off-grid systems, which as we know, might lead to a grid death spiral. 

The following map shows the distribution of the T&D infrastructure in Kenya obtained from the African Energy report of 2018/2019. 

The highlighted areas are sparsely populated with a huge potential for development. They exhibit a clustered kind of settlement mainly served by SHS suppliers. This market can be best served using interconnected micro-grids that can be run by the national utility. It is also possible to develop a distribution business case models for utilities and work with IPPs to provide affordable and usable power in these places. 

A study looking into new business models for utilities compares the traditional core business models with the possible future utility models. The distribution case and partner of partner's cases can be the best pick if these monopolies are to play a critical part in facilitating electricity access in the remotest of areas. 

Our first article explored the possibility of using mini-grids to power communities (" A case for minigrids" ) . This article delves into different forms of clustering techniques that can be deployed to create smaller centralized-decentralized grids for areas that are not a national grid. 

Micro-grid clustering 

Micro-grids are being developed across the world for various reasons. The two competing ones include the need to provide grid reliability in cases of adverse and unexpected events and secondly the need to deliver electricity at load centres economically. This means that costs of transmission and distribution are always reduced whenever a micro-grid is developed. The design complexities involved in the micro-grid control architecture is left out of this discussion. This article explores possible interconnections that can be implemented using existing micro-grid technologies to achieve more robust system within a localized area. 

Such designs can be implemented at different levels of governments to facilitate access to electricity. This discussion is largely based on Micro-grid Clustering architecture research and explores the suggested options in a local context. 

Mini-grid and micro-grid clusters can be interlinked together through distribution lines and smartly controlled to ensure that the energy needs for the target customers are met. This has been implemented before by different utilities for utility support. It is known that the deployment of microgrids in the developed world has been primarily based on the need to improve system resilience and provide ancillary services such as reactive power control, supply of reserves and assistance in load following, among other services. However in the cases of countries with very low level rural electricity access, mini-grids are the main source of power and therefore there is need to develop them as a complete power system on their own and not as a transition as the areas await to be connected to national grid. The goal is to provide affordable and usable power to the customers as opposed to the national grid connection. As such, off-grid clusters of microgrids could be smartly connected to provide a kind of localized electricity market. In this case, it is necessary for institution of regulations that would guide such energy transactions between microgrids. 

There are two ways through which the SSA utilities could take part in these markets. Firstly, in the case of off-grid business, it is possible for the utilities to develop local grids in conformance with the national grid codes to facilitate and allow the current renewable energy investors to use the network in electricity supply. This would leave the utilities with the role of maintaining the network as well as monitoring the performance of different sources of the microgrids. The utilities are thus able to create local grids and networks which has been the difficult part in micro-grid investments. Distribution is a capital-intense business and few investors have shown interest in doing it the SSA energy market. This form of interconnection has been proposed by Siemens to improve the reliability and resilience of the Puerto Rico electric grid. In addition to playing a role in this market, the utilities would be able to generate income by charging a network user fee. 

Secondly, in the case of microgrids developed on the peripheries of the grid, it is possible to use the grid as support system to the micro-grid and vice-versa. This means that the performance of the micro-grids can be enhanced having a tie-line between them and the grid. In this case, different micro-grids can be interconnected with an n-1 contingency plan. 

Whether the microgrids are connected to the grid or not, two topologies have been proposed. The first case consists of the master and slave micro-grids interconnected together. In this case, the master microgrid controls the slave microgrids intelligently. Conversely, in a centrally controlled topology, there exists an external control centre which manages the interconnected microgrids. The following figure shows the two topologies. These topologies define the interactions between two or more microgrids.

In a utility-private sector collaboration business model, the utility retains value chains which in this case include the management of the distribution network and secondly the coordination of energy sales between the two or more entities.

It is also important to consider the design of the layout of connections in a microgrid cluster. This is because each layout has a cost implication that must be considered before embarking on the microgrid development process. The detailed discussion on these can be found in the Micro-grid Clustering architecture research which has informed this article. Briefly, three layouts exist. These include the parallel connected microgrids (PCM), the Grid of Series Interconnected microgrids (GSIM) as well as the mixed parallel-series connection (MPSC). The PCM model is most applicable in most cases due its simplicity. It can be best used where the grid is available and able to offer support for each of the microgrids in case of an outage. The GSIM and MPSC are applicable in most clustering techniques which could include off-grid connections. The cost of implementing GSIM is higher compared to both the PCM and the MPSC. Considering an n-1 contingency, the application of GSIM requires that the sizing of all the components consider the effect of an outage on the system. As such, the distribution lines as well as the inverters and the generation components must be sized to handle twice the capacity of the largest microgrid in the cluster. As such it is costly in implementation terms.

The MPSC connection has a lower cost compared to the GSIM and higher cost compared to the PCM. It would be most recommended because of its reliability and possible faster recovery in case of power outage in one of the microgrids. The MPSC model takes two forms, which include the open loop as well as the closed loop. The figure below illustrates the PCM model , MPSC open loop and the MPSC closed loop.

Ideally, MPSC provides an appropriate path for clustering the microgrids since it provides for an alternative pathway to power the loads served by the other microgrid that may experience an outage. It is designed to cater for loss of generation. The PCM model is a workable solution where there is an existing grid and may be crucial in enhancing system resilience.

In conclusion, it is possible to power areas which are sparsely populated by considering the application of microgrid clusters. Arid and semi-arid areas far from the national grid can have a state of the art decentralized grids operated by the utility in conjunction with the private sector. With low access to electricity in rural areas, policy makers need to normalize investing in well designed microgrids and mini-grids to provide electricity access to more than half a billion people who cannot access this resource in SSA.

-----

This thought leadership article was originally shared with Energy Central's Grid Professionals Community Group. The communities are a place where professionals in the power industry can share, learn and connect in a collaborative environment. Join the Grid Professionals Community today and learn from others who work in the industry. 

-----

Earlier:

2020, April, 9, 11:35:00 SUB-SAHARAN AFRICA RECESSION 2020 Growth in Sub-Saharan Africa has been significantly impacted by the ongoing coronavirus outbreak and is forecast to fall sharply from 2.4% in 2019 to -2.1 to -5.1% in 2020, the first recession in the region over the past 25 years, English

2020, March, 16, 10:20:00 AFRICA HOPES FOR GAS Africa hopes to exploit its 509.6 Tft3 of proven natural gas reserves, which amount to nearly 7.3% of global total reserves of 6,951.8 Tft3. English

2019, November, 11, 12:50:00 AFRICA'S ENERGY DEMAND GROWTH TWICE Energy demand in Africa grows twice as fast as the global average, and Africa’s vast renewables resources and falling technology costs drive double-digit growth in deployment of utility-scale and distributed solar photovoltaics (PV), and other renewables, across the continent. English

-----