A more exciting time can be expected in the electrical industry, as the scale and pace of change increases. This is the view of Mark Waldron, the chair of Cigré’s technical council, and Dr. Rob Stephen, the organisation’s president. The changes will affect the way in which infrastructure is built, while the main drivers for change are sustainability and environmental impact, and the challenge of supplying an additional huge number of people with electricity, they said.
These comments were made at the opening the Cigré 8th Southern African Regional Conference which was held on 14-17 November 2017 at the Lord Charles Hotel in Somerset West. The Conference is the biennial discussion forum organised by the Cigré Southern Africa Committee for members, associates and experts from Africa and developing economies. The theme of the conference was: “Electricity supply to Africa and developing economies: challenges and opportunities”.
The conference was attended by 353 delegates from 43 countries and a total of 66 papers on various subjects in 11 sessions were presented. The objective of the conference was to provide a regional platform to share information between electric utilities, international manufacturers, universities, standardising bodies, and authorities on the selected topics of the challenges and opportunities in the field of enabling the supply of electricity to Africa and developing economies. The conference was preceded by a day of tutorials covering a number of topics, and was followed by a day of technical tours.
The welcoming address was presented by Mark Waldron, the chair of Cigré’s technical council which was meeting in South Africa at the same time, and the keynote address was delivered by Dr. Rob Stephen, the president of Cigré.
Both emphasised that a more exciting time is to be expected in the electrical industry, as the scale and pace of change increases. The nature of change will have an effect on the way that infrastructure is built in future. The main drivers for change are seen as sustainability and environmental impact, and the fact that a huge number of people do not have access to electricity.
The first one is driving the adoption of renewable energy (RE) plants, with government programs having fixed targets. RE is variable and not always in the same place as the demand or load, resulting in new network concepts needed, to integrate RE on a large scale.
There is new concept emerging in the transmission and distribution (T&D) sector, that of the distribution system operator (DSO), as the amount of distributed small generation increases. Distributions networks are changing from unidirectional flow of energy to bi-directional or multi-directional. This is a spin-off of the growth of renewable energy plant. During the conference, a Memorandum of Understanding (MoU) was signed between Cigré and AFSEC, the African Electro Technical standardisation commission.
The role of the transmission network as a bulk electricity transport platform, which was seen to be diminishing, is being re-established as a means of balancing generation and demand. The transmission network of the future will need to be capable of interconnecting load regions and large centralised renewable generation resources, as well as provide connection between countries and energy markets over a wide region. The global grid, which interconnects all countries is seen as a future reality.
Developing the system of the future is not only a technological challenge but requires regulatory adaptions and political co-operation in most areas In future the medium and in particular the low voltage distribution system will play a significant role in regulating the system. Co-operation between TSOs and DSOs will have to be intensified. Control of the system will be complex and most likely solved by distributed intelligence. Cyber security is becoming more important with the advent of the smart grid. Apparently, 140 000 hacking attempts are experience daily by utilities in the USA.
Cigré has an informal partnership with the world bank, on the financing of low cost optimization of electrification programs. Many solutions that are subject to loans and grants are country and manufacturer bound, and the organisation is seen as an independent body which can make recommendations on purely technical grounds, a system that the world bank is aiming for.
Papers and presentations
Major themes that emerged over the eleven sessions were:
Connection of renewable energy systems and integration into the grid remains a challenging area, in spite of the inversing experience in this field. South Africa still has a low penetration of RE with a limited impact on inertia, but this will change as more RE is installed. The capacity of the network to absorb more renewable energy, particularly small scale embedded generation (SSEG) is matter of concern. Plans to upgrade HV transmission networks have been made, but little planning for MV and LV networks has been done. This largely driven by a lack of information on the amount and location of SSEG.
Interconnections between networks are likely to increase in future and this brings network stability into question. Cases of instability and network oscillation have occurred on interconnects in the past, and a full analysis of the networks needs to be carried out before interconnection is finalised.
The session on transformer health featured a paper on excessive gassing observed in transformer installed at several PV plants, a phenomenon which has been observed in wind turbine transformers. Investigation did not reveal a conclusive result, but it was suspected that thermal cycling was the cause, as was the case with wind turbine transformers. Extreme thermal cycling occurs in PV plant as the plant is idle for a relatively long period at night and ramps up and down at the start and end of the daily solar cycle. Passing cloud can cause numerous cycles during the daily cycle.
Provision of secure and reliable supply of electricity to rural and unserved areas remains one of the greatest challenges facing the industry. The problem exists not only in rural areas but in informal urban areas as well. The main issue for urban areas is the safety of the connection, metering and collection of revenue. Backyard connections are often encountered where shacks are built in the backyards of existing dwellings, with “informal” connections to the existing supply. A solution adopted in Cape town installed a safe separate metered supply to the backyard installations. In rural areas microgrids are proving to be a solution, but full grid connection still remains the optimum goal.
System resilience is also a concern with the possibility that large scale failures can occur, with many networks running on the edge of secure systems. Most large operators have developed contingency and response plans to prevent such large scale failure and to recover as fast as possible if such failures occur. The move to distributed generation has an a yet undetermined effect of network resilience, but will no doubt increase the complexity.
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