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.



Modern trends in long distance power links

Many of the changes in the way the world works lead to new opportunities for different technologies. This has led to a new approach to electricity distribution using HVDC – High Voltage Direct Current – transmission lines, operating at up to 800 kV. Such power transfer lines are now installed particularly around Europe, and across China.

When power stations were smaller, and based near the major population centres, they tended to serve a local area with electric power, and this was best delivered using AC transmission, via local transformers, to produce the 110–240 VAC power distributed to each street. (As an aside, even more locally around the power station, district heating schemes could distribute some of the power using thermal transmission.) To provide the electrical energy transmission further afield, higher voltage AC transmission lines were used to feed a major substation, then distributing the power to local transformers, creating local networks – like the branches of a tree.

Currently, the new solar farms and wind power sources have been built well away from the major centres of population, where the land (or sea) space is available, and the conditions are right. Plus, hydroelectric plants are necessarily placed near the river or water flows, naturally located in the hills. All these sites are at the end of the thinnest branches of the old ‘distribution tree’, so new transmission lines are needed to take the power back to the population centres.

Long distance transmission

China also faced this problem, with economic development and a growing demand for power by the population in the west of the country, with the major new power stations and hydro plants located in the east. For transmission of power over distances like 500 km or more, the reactive power flow due to the large cable capacitance limits the maximum possible transmission distance, as the power loss becomes high. The installation and maintenance costs for the necessarily taller and wider dual pylon AC overhead transmission lines, also becomes excessive.

For such long distance transmission, HVDC comes into its own economically because the line losses are much lower, as are the line installation and maintenance costs, since HVDC (at around 600 kV) can use a single overhead pylon carrying just two conductors, or can use a buried cable. The higher costs of the HVDC terminal equipment, needed at both ends to convert the power back to AC for local distribution, are more than offset by the savings in the transmission line costs. Plus the environmental impact of the HVDC underground cables is insignificant, compared to overhead AC transmission. The possibility of using underground cables means HVDC links can deliver power into cities and urban areas where the use of pylons and overhead cables would not be tolerated.

So, over the last few years China has installed 24 projects using HVDC power transmission: one of these used a 1670 km line carrying 8000 MW of power to the east. The supplier for 19 of these projects, including the largest one, was ABB Power Systems. ABB also claims to be the major supplier of recent HVDC power transmission projects throughout Europe, and the rest of the world.

Undersea links

In Europe there are many power networks, based around different standards that were developed by the different countries: these AC networks can run at different frequencies, and are not often synchronised. It makes sense to wish to trade power between networks, to make use of surpluses when these are available, and cover for power outages or other unforeseen events. Transferring power using HVDC links makes sense, firstly because the receiving terminal can convert the DC to an AC power source running at the same frequency as the receiving network, plus the local ­engineers can phase synchronise the generated AC power with their other sources.

The second big advantage of HVDC links is that they can run in economically constructed underwater cables, to islands and across major sea routes, such as from the UK to France, or Norway and Sweden to Denmark, Germany and Finland. The NorNed link, from Norway to the Netherlands, is the world’s longest submarine power cable, at 580 km length. Similar HVDC links are used to supply power from hydro schemes and wind farms in the north of Scotland, across the estuary of the Moray Firth to the heavily populated Inverness/Aberdeen area.

The growth of offshore wind farms has led to this green energy being sent onshore using an HVDC submarine cable, and also vice versa, in the sense that offshore oil production platforms are now being supplied with power from onshore, delivered by cable, and just converted to AC power on the platform – saving weight and complexity offshore. Plans are being made to extend this European network, with possible hydro-electric power being delivered by cable from Iceland to Scotland, and from Norway via the Shetland Islands, then also to Scotland.

More importantly, in an African context perhaps, solar farms in North Africa will be able to transmit power to Europe via Spain from Morocco and to Italy from Tunisia and Libya.

This article first appeared in my column in the South African Journal of Instrumentation and Control, November 2017 issue. SAIC is published by Technews in South Africa.

ABB automation increases capacity 10x for Tate & Lyle food additive plant

When Tate & Lyle acquired Biovelop, a Swedish manufacturer of oat based food ingredients in 2013, the factory in Kimstad, Sweden was modernized and expanded by installing automation systems, variable speed drives, motors, motor control cabinets  and valve positioners from ABB Automation. In 2016 the remodeled plant celebrated the first anniversary of operations with the new systems and significantly increased production capacity.

The global market for specialty food ingredients, including health and wellness products, is growing, with annual sales of $51 billion and annual growth rate of 4-5%. Oat ingredients have been actively involved with this trend as they offer some key nutritional and functional benefits. In particular, oat contains beta glucan, a soluble fiber that has been shown to lower cholesterol and reduce post prandial glycaemic response – claims that have been approved by the European Food Safety Authority (EFSA). In fact, it was these properties of the grain that made the sector an attractive one to Tate & Lyle, and triggered the decision to diversify its portfolio into this sector.

“We have seen a more than tenfold increase in capacity with the same number of shift operators compared to four years ago,” said Annika Werneman, Tate & Lyle plant manager. “It’s a huge change in such a short time, and it means that we’ve gone from a low-level facility to one that can deliver high quality product to our customers globally.”

Advanced automation technologies in the plant run critical food processing equipment -including pumps and decanters: material handling machinery is also used to transport the dry food products. ABB delivered automation equipment that included 85 variable speed drives (VSDs), with power ratings ranging from 0.37 kW to 55 kW, as well as ABB MNS 3.0 motor control cabinets and low voltage motors. ABB also delivered 44 Digital Electro pneumatic positioners (TZID-C) , which use the Hart protocol to communicate with the control valves.

“We needed a process that was highly automated and could run 24 hours, seven days a week, all year long,” Werneman continued. This meant building a system that enabled Tate & Lyle engineers to digitally interact with the system, commission (start) devices, and diagnose performance deviations or failures from anywhere in the world. This not only helps ensure operational consistency, but also reduce the total cost of ownership by enabling staff to manage the processes without being physically present at each site.

Such interactivity was enabled by the ABB fieldbus automation for the drive controls, providing flexibility as well as remote monitoring of the plant performance. “I like that ABB designed the system so that the fieldbus responsible for device control is split from the fieldbus used for asset management,” explained Leo Dijkstra, power & controls team leader Europe at Tate & Lyle. “This ensures that I can make any changes to the configuration of the devices without the risk of the whole network going down.”

At Tate & Lyle, they place great importance not just on what they do, but how they do it. “We are working continuously wherever we can to reduce the environmental footprint of our operations,” said Dijkstra. ABB was well placed to help as it has developed a portfolio of products and solutions that improve industrial energy efficiency.

“In our pump applications alone, we are using up to 50 percent less energy thanks to the variable speed drives, and these have been running non-stop for the last two years without a single failure,” Dijkstra continued. “What’s more, ABB was so quick to deliver products that we even had the first VSD delivered in just a few days.”

Although the nearest ABB support is only a ten-minute drive away from the Kimstad factory, the fieldbus flexibilities in the drives enable Tate & Lyle to rely on its own staff to handle the ABB equipment remotely. “Our work with Tate & Lyle illustrates the benefits of digitization, which can yield immense productivity and output gains from existing facilities,” said Petter Hollertz, area sales manager at ABB. “The improvements at this plant also show what great teamwork between the equipment supplier and the user can accomplish, as we worked together as true partners on this project.”

Advances in battery technology

The opportunities for spin-out businesses and industries from university research projects are multiplying. The growth in this sector comes from the acceleration of technology in general, but also because the increased investment in education means there are a lot more research students, some with good ideas, but others just looking for topical subjects to latch onto for their research project. Also, industry has learnt that by funding some low cost university research, other ideas might emerge that might be of benefit.

A lot of attention is being given to new designs of battery, as there are some well-known major commercial projects where new systems are needed. First to come to mind would be batteries for electric cars like the Tesla. Here, low-cost, lightweight and relatively compact devices are needed, with high-power output and fast charging. Second are the batteries (or systems) needed to store the power generated by solar farms or wind turbines, during the hours when it is not needed, so that it is available for different times of the day. Possibly lower down the priority list are the small long-life battery systems needed for IIOT sensors and industrial sensors in general. These do not have the major numbers, or the (relatively) high price, so do not attract as much attention.

Eliminating standby power drain

So, it was all the more interesting to hear of research at Bristol University, in the UK, where Dr Stark and his colleagues in the Bristol Energy Management Research Group have developed an electronic chip that can switch on a sensor only when that sensor is being asked to provide or monitor data: for the rest of the time the chip and the circuits which it controls consume no energy at all. It may not be a new battery development as such, but it would allow a much extended battery life, by eliminating all stand-by current drain.

The principle is that the chip uses the small amount of energy transmitted in the interrogation signal from the system asking for the data, to trigger a circuit that switches the device on. The interrogation signal could be from an infrared remote control, or a wireless signal. The team developed their circuit using the same principles as those used in computers to monitor their internal power supply rails – to ensure the voltage does not dip below a certain threshold. The trigger signal uses a few picoWatts of energy, and a signal threshold level of 0,5 V, which is achievable from a passive sensor, just using the received wave energy.

The natural follow-on from this concept is that the trigger signal on some sensor applications could be derived from the event being monitored, such as a rapid increase in the sound or vibration levels of plant machinery. Also, for a security alarm, the movement of a hinge or similar could be sensed magnetically. Conventional power management techniques would be used to switch the sensor off once the data has been transmitted to, and acknowledged by, the monitoring systems.

Power storage

With solar and wind energy providing such a large part of the power used by the National Grid in certain areas, many ways are being researched to achieve power storage over the short term, such as 24 hours. There are already companies providing large storage systems with banks of conventional batteries, acting like very large uninterruptible power supply (UPS) systems. In Spain and the USA there are solar collector systems where the sun’s heat is concentrated onto a central collector, melting sodium salts: the heat is later used to drive a steam turbine. Further systems are being trialled where surplus energy is used to liquefy gases, or compress them in a high pressure chamber, later the stored gas can be used to drive a turbine generator.

A novel development of a battery cell reported recently is the use of a low cost electrolyte for use with aluminium and graphite electrodes. Dr Dai, at Stanford University, in collaboration with Taiwan’s Industrial Technology Research Institute, demonstrated such a battery powering a motorbike in 2015, but the electrolyte was expensive. The new electrolyte is 100 times less expensive – it is based on urea. Dr Dai sees this as a useful solution for storing solar power, even domestically – maybe new houses will have such a system underground, and call it a “Power storage pit”!

This article was first published in the April issue of “South African Instrumentation & Control”, a TechNews publication. This journal is kind enough to publish an article from Nick Denbow every month, as a report on stories of interest from Europe.

Yokogawa EPMS and SCADA for the UK’s BPAL pipeline system

Yokogawa has received an order from the British Pipeline Agency Limited (BPAL) to supply a management and control system for one of the UK’s major multi-product fuel pipeline systems, to replace the current BPAL pipeline management and SCADA systems.

The BPAL UK pipeline system consists of three integrated multi-product fuel pipelines that link two, refineries, one at Ellesmere port on the Mersey near Liverpool and the other on the Thames in Essex, to inland distribution terminals. These pipelines, operational since 1969, meet over 50% of the jet fuel needs at London’s Heathrow and Gatwick airports, and are altogether some 650 km in length. BPAL, jointly owned by Shell and BP, are the operators of these pipeline systems (known as UKOP and WLWG), which are owned by a consortium of partners.

This order is for Yokogawa’s Enterprise Pipeline Management Solution (EPMS), which will manage functions such as delivery scheduling and oil storage, and their Fast-Tools SCADA software, to monitor and control the oil pipelines and related equipment such as compressors. The EPMS uses specific gas and liquid applications that enable a pipeline operator to manage delivery contracts in a time and energy efficient manner. With the SCADA system covering monitoring and control, the EPMS will integrate the management of the SCADA data. Delivery of these systems will be completed by March 2018.

Further order for UAE Power and Desalination Station

Yokogawa also recently received its first ever DCS order for a power and desalination plant in the UAE. The company is to supply the Sharjah Electricity & Water Authority (SEWA) with control and safety systems, plus field equipment, for Units 7 and 8 at the Layyah Power and Desalination Station.

Each unit comprises a 75 MW oil and gas-fired thermal power plant and a 27,000 m3 per day multi-stage flash (MSF) desalination plant: a technology that involves the heating and evaporation of seawater in multiple vacuum distillation tanks to produce steam, which is then condensed to produce fresh water. Such systems are energy-efficient because they use the heat from the steam that is created in the vacuum distillation tanks.

Yokogawa Middle East & Africa will deliver the CentumVP integrated production control system for the boiler, turbine governor, turbine protection system and the desalination plant at each of these units, as well as the ProSafe-RS safety instrumented system for burner management and boiler protection. The field instruments will include Yokogawa products such as the DPharp EJA series differential pressure and pressure transmitters, continuous emission monitoring systems (CEMS), and steam and water analysis systems (SWAS). In addition to being responsible for engineering, the company will provide support for the installation and commissioning of these systems, with all work scheduled for completion by September 2017.

Demand for electricity and water is soaring throughout the Middle East due to their rapid economic growth. Power and desalination plants that rely on the region’s abundant oil and gas resources make up an important part of this region’s infrastructure.

ABB 1.2 Million Volt Transformer

ABB has developed, manufactured and energized a 1,200-kilovolt (kV) ultra-high-voltage power transformer to support India’s plans to build a 1,200 kV transmission system, supplementing the existing 400 kV and 800 kV transmission grid as demand for electricity increases. The transformer was manufactured and tested at ABB’s state-of-the-art Vadodara facility in India.

Ultrahigh voltage (UHV) 1,200 kV alternating current (AC) power

Ultrahigh voltage (UHV) 1,200 kV alternating current (AC) power transformer installed at Bina site – Level 2

This 1.2 million volt transformer represents the highest alternating current voltage level in the world and is installed at the national test station at Bina, Madhya Pradesh in Central India, as part of a collaborative initiative by the country’s central transmission utility, Power Grid Corporation of India Limited (POWERGRID).

India’s geographic span means that resource-rich generation centers and urban and industrial load centers are often far apart therefore requiring efficient power transmission. Along with the country’s commitment to enhance the contribution of renewables, these factors are driving the development of an ultra-high-voltage transmission infrastructure.

The 1,200kV transmission system will help strengthen the grid and enhance load capacity up to 6,000 megawatts (MW). Transmission at higher voltages enables larger amounts of electricity to be transported across longer distances, while minimizing losses. At the same time, less space is needed for fewer transmission lines, which reduces the environmental impact and overall cost.

“ABB has a pioneering track record in India and this 1,200 kV achievement is another concrete example of our commitment to support the country in the ongoing development of its power infrastructure” said Claudio Facchin, President of ABB’s Power Grids division. “This project also underlines how ABB delivers differentiated value through innovation and customer collaboration, both key elements of our Next Level strategy.”

In addition to the transformer, ABB has also developed a 1,200 kV circuit breaker that was previously commissioned at the test station. This was the first hybrid gas insulated switchgear in the world to be energized at this voltage level. The uniquely designed circuit breaker is safely housed with the disconnector in a tank filled with insulating gas – resulting in a space saving potential of up to 60 percent compared with conventional designs.

New ABB inverter boosts solar performance

The new ABB PVS980 central inverter – an essential component in every solar installation that converts direct current (DC) produced in solar panels into alternating current (AC) for use by electricity grids – allows the amount of incoming solar power connected to a single inverter to be increased by as much as 40%: a dramatic improvement that completely changes the economics of a solar installation. Thanks to its increased power, the PVS980 inverter also means a site needs 30% fewer inverters than previously.

The PVS980 high power 1500 VDC central inverter is capable of processing more incoming DC power from photovoltaic (PV) panels through one inverter, reducing the total number of inverters needed on-site, which helps reduce overall costs across the lifetime of a solar plant. Central inverters are used for applications such as large field installations as well as large arrays installed on buildings and industrial facilities. Originally introduced at the Intersolar exhibition as a concept last year, the PVS980 is now shipping commercially and has already seen strong interest among customers, with a number of pilot projects in place. The new inverter is designed to seamlessly integrate into digital smart grids and operate efficiently, while reducing the carbon footprint of the installation.

ABB engineers have improved the compactness of the device, enabling a power density increase of more than 40% – making it possible to build large power rated inverters in the same physical size. Avoiding external air entering the critical compartments of the inverter, the equipment can operate from below freezing to extreme heat in 100% humidity without jeopardizing functionality. The very wide temperature capability offers full performance without derating at up to 50°C, in a waterproof and dustproof enclosure.