The 2016 Paris Session was again a great success with more than 3,290 attendees discussing around 400 papers across the 16 fields of activities. A total of seventeen papers were accepted from CIGRE Australia members. They covered a wide range of topics including transformer monitoring, new projects, asset management, fire management and prevention, stand alone power systems, forecasting PV contributions, high renewables penetration and cyber security. Australian Cigre members made a number of prepared contributions and attended working group meetings. This year’s NGN Scholarship winners also made presentations.
A dominant theme of the Session related to the continuing challenge associated with incorporating ever-increasing proportions of intermittent renewable generation into the power systems. A few highlights from some of the discussion areas are presented below for your general information.
The close planning coordination between transmission and distribution is growing in importance. Uncertainties relating to size, timing and location of renewable energy sources remain a challenge. However, there is a level of predictability to these sources, which needs to be taken into account as it is with traditional generation. There is also a concern that the market rules may not be providing the right incentives to secure investment in transmission and distribution networks.
Coping with low inertia at times of low demand in systems with a high degree of intermittent renewable penetration is a growing challenge. New functionalities within power electronic based generation and energy storage systems have significantly improved power system performance. The use of validated models to assess these tools is important.
Concerns were expressed about modeling software limitations for aspects such as ramp rates and the steep learning curve required to master the tools.
Considerable effort is being placed on developing solutions and modeling tools to deal with the ever-increasing penetration of intermittent renewables. There is also a need to improve communication and data exchange methods between transmission and distribution operators.
Forecasting of wind and solar needs improvement and a presentation from Australia provided a good example.
Challenges with managing power systems with very low levels of reserves were discussed and the need to look at both a long and short-term perspective was emphasized.
Restoration strategies for power systems with a high penetration of intermittent renewables are now needed. Previously these would have been ignored but this is no longer possible in some power systems. The use of these sources in the restart process is needed but much work is still needed to achieve this.
The major disturbance workshop included a presentation on the solar eclipse over Western Europe, which was discussed in the last ITL. Other examples include the market implications of intermittent renewables in South Australia by Rainer Korte from Electranet and the coordination challenges resulting from the replacement of coal fired generation with gas fired generation in California and the resulting inconsistencies between the gas and electricity markets that were identified.
Voltage source converter technology continues to develop and is now preferred for use in weaker networks.
Results of a performance survey on FACTS devices were presented. This is of particular interest to Australia and New Zealand as we have a significant number of these devices installed.
The trend towards Supergrids and Microgrids is providing a number of opportunities to use HVDC and MVDC. These solutions are aimed at more effectively managing the diversity of output of the intermittent renewables.
The use of DC and power electronics at the distribution level is gaining traction and this was an important are of discussion.
Cyber security is front of mind for a number of Australian Utilities and was a hot topic in a number of forums, particularly in D2 which had a dedicated preferential subject on this topic. Cyber attack is perceived as a threat to monitoring systems. Australia provided an important contribution on how this is approached in Electranet. France has a trial facility using direct tripping from an intelligent electronic device. The aim is to improve efficiency but there are also concerns with cyber security.
There is increasing deployment of integrated and modular units or prefabricated bays allowing more to be done in the factory, improving safety and reducing the scope for site disturbances. This was highlighted in the NGN showcase presentations from Australia and Japan.
Substations seem to have a longer lifetime than the renewable technologies now being connected to them. For example, lifetime assessments for GIS indicate a service life of greater than 50 years. This needs to be an important consideration when designing the substation.
The use of robotic devices for monitoring and allowing access to difficult to reach equipment such as the top of insulators is increasing rapidly. Legislation associated with using these applications varies across the world, particularly in relation to drones. Drones are also being used for transmission line inspections. Experience shows that the solutions are viable, efficient and safe but further improvements are needed.
A topic of particular interest to Australian industry related to comparisons of ester filled and mineral oil filled transformers. Research suggests that the higher water solubility of esters leads to less cellulose degradation compared to mineral oils, which should lead to an increase in the life expectancy of the transformer. On the other hand, the ability to absorb more moisture may not be sustained in the long term as the moisture in combination with the high operating temperature will result in higher acidity and higher liquid conductivity.
A workshop was held to look at the use of alternative gases to SF6, as this is a potent greenhouse gas. While SF6 is still the best performer, much more research work is needed, particularly in relation to the life cycle analysis of SF6 and the alternative gases. There is also a concern with the management of different gas mixtures during construction or maintenance.
Non-intrusive methods for condition assessment of transmission and distribution equipment are being examined as this leads to lower equipment failure rates. Various techniques are being examined to monitor overstressing of equipment in relation to current voltage and fault levels. One example described was the use of an on-line self-powered temperature monitor, which is small enough to be installed in areas of equipment to monitor critical thermal parts. By using mathematical modeling it is possible to foresee thermal overstressing and take measures to avoid it.