MVDC Power Transmission

Azeez Mohammed, president & CEO of the GE Power Conversion business discusses how MVDC technology is creating a more secure and higher-capacity grid for the future. Thanks to the MCDC technology, Scottish Power Energy Networks’ Angle DC project – first of its kind in Europe – will provide a 23% power capacity increase for supplies to Anglesey. Similar technology is being used in offshore wind applications, giving up to  15% cost savings.

Transforming Power Grids for an Efficient Future

With a fast-growing global population and increasing levels of industrialisation, demand for electricity is expected to soar 60% between now and 2040. That means power grids will be called on to transmit more power, more efficiently. And to do so, they’ll have to adapt to an evolving energy landscape.

Today’s grid is still structured around transmitting electricity from a handful of large, centralised power plants running on coal, oil, gas and nuclear. While these will continue to dominate the mix for years to come, renewables are increasingly making their presence felt – and are expected to supply a third of global power by 2040.

With renewables growth comes an increasingly diverse distribution network – from remote and offshore generation sites to microgrids. All must be brought together to ensure we continue to have a reliable, resilient power supply. The challenge now is that the majority of power grids are made up of decades-old infrastructure that’s simply not – yet – up to the task.

Laying the foundations

Creating a future-proof power grid means fusing time-honoured knowledge with forward-thinking technology. For over 100 years, GE electrical engineers have recognised that DC electricity transmission is more efficient than AC. Now, DC is becoming more prominent – both at the beginning and end of the grid. DC is produced by wind turbines and solar PV and used by everything from smartphones, laptops and electric cars to the data centres that keep our digital world up and running. However, having to convert back and forth between AC and DC along the way leads to wasted energy through resistance and heat.

AC may have won the “War of the Currents” that raged between the Edison Electric Company (which favoured DC and would become General Electric) and Westinghouse (which favoured AC) in the 1890s. This was due to its ability to easily step up voltages to the higher levels needed to transmit it over long distances and back down again for safe usage. But today, new power conversion and transmission technology means it is becoming more cost-effective to use DC to transmit at higher voltages, with less energy losses. The same attractive cost story applies when it comes to integrating new, often remote, DC-producing renewables into the wider grid network.

At the GE Power Conversion business, we’re developing the use of DC to enable more efficient power transmission to and from remote areas – both onshore and offshore.

Strengthening the Anglesey power supply

At the GE Power Conversion business, we are delivering Europe’s very first medium-voltage direct current (MVDC) link as part of the Scottish Power Energy Network Angle DC project in Anglesey and surrounding North Wales area. A growing demand for electricity in the region, combined with increasing volumes of renewable generation, is putting the existing 33-kilovolt AC links between the isle of Anglesey and the Welsh mainland under strain.

Converting the existing AC connection to MVDC could help it to carry more than twice the power and do so more efficiently. GE MVDC technology is providing a critical project asset, as it allows for the creation of a more-secure, higher-capacity grid without the need to overhaul existing infrastructure or install new power distribution assets.

Instead, GE will install MVDC power modules at the two existing substations in Bangor and Llanfair PG, where the AC to DC conversion will be performed. GE MV7000 power electronic inverters will transmit the power via the existing 33-kilovolt AC overhead line and cable circuit, increasing the power available to Anglesey by 23% to meet its future needs without additional environmental impact. What’s more, the DC equipment will assist in the provision of further grid support, as the inverters are able to support the AC voltage at each substation.

This MVDC technology works in much the same way as our high-voltage direct current (HVDC) projects, but on a smaller and simpler scale. For example, a comparable HVDC system would operate at 320-400 kilovolts DC, whereas the Angle DC project will operate at 27 kilovolts DC—demonstrating how this technology can be scaled to fit a variety of customer needs.

Lowering the cost of offshore power

From wind turbines stationed far out at sea to solar farms in inhospitable deserts, renewable generation networks are often found in hard-to-reach places. Getting the power generated to a centralised grid via AC can waste energy and keep renewable electricity costs higher than they need to be.

Now, similar technology behind the MV7000 converters used for Angle DC has also been successfully trialed for use in remote power networks. Our PassiveBoost solution will enable DC power transmission, opening up the potential to boost electrical output from these remote sites while also reducing power costs.

PassiveBoost is an MVDC converter which provides a straight replacement, with the same footprint and volume, for the AC transformer inside every wind turbine. This helps to facilitate a direct connection to an efficient MVDC power collection grid, resulting in a lower cable cost and no need for an expensive and complex DC breaker. A 6 megavolt-ampere converter was designed and tested at the GE power test facility in the UK. There, it successfully demonstrated the capability of generation, distribution and protection at MVDC, highlighting efficiency levels that could bring a 15% cost saving for offshore wind electricity by significant reductions in component count, cabling costs and removal of need for offshore platforms.

Greater grid control through data-driven insights

To drive further efficiency across the power grid, GE can also offer VISOR 2.0, an asset management tool that provides remote connectivity to key assets. This not only enables an improved service response time, but also access to real-time support and advice in the event of a fault or problem. By pairing this tool with the GE Data Historian, which collects, processes and stores data, customers can more easily review the capabilities of their MVDC system. Its ability to capture and analyse data about asset performance means customers can then develop optimum control algorithms for the distribution system, helping to ensure the grid is always functioning as effectively as possible.

As electrification within all industries gathers pace and the burden on existing energy distribution networks increases, we’re ready to put our expertise into action where it’s most needed.

 

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