Marchwood Power Station Takes Reliability and Availability to New Levels

• Already efficient power station becomes even more so using Siemens total engineered solution technology with improved operating efficiencies (year-on-year savings)
• Increased reliability, availability, flexibility of operation
• Reduced maintenance, spares and CO2
• Simplified solution with lower cost of ownership

Since commercial operation began in December 2009, Marchwood Power Station has been one of the UK’s more efficient combined cycle gas turbine (CCGT) power stations ever built, with the highest availability in the UK.

CCGT power stations utilise a combination of both gas turbine and steam turbine technology, whereby the steam turbine is driven by virtue of the heat produced via the gas turbines.  Typically, this can produce an overall efficiency in the region of 60 per cent.  Yet, further improvement remains a continuing quest for all energy users, and Marchwood has utilised Siemens control systems (CS) and integrated drive systems (IDS) creating a total engineered technology solution to upgrade itself to an even more efficient and reliable electricity generator.

Now capable of generating in excess of 900 MW of electricity, enough to power a million homes around Southampton, Winchester and the New Forest, Marchwood plays a key role as one of Britain’s best-performing power stations. 

Unfortunately, in 2010 the station began experiencing major issues with the three main water cooling pump systems, responsible for providing cooling water through the steam turbine condenser and ancillary cooling system sections of the plant.  Reliability was becoming compromised as the swirl regulators used to regulate the flow of water were sticking, due to the associated mechanical linkage, which consequently led to difficulties regulating the flow.  Additionally, the gearboxes linking the motor outputs to the cooling pumps were also a significant weakness, due to oil leakages, leading to premature wear, excessive noise and heat issues.  

The water cooling pumps are very much at the heart of the efficient operating system at Marchwood.  The water flow at the site was controlled by a fixed speed pump package, comprising an AC induction motor, gearbox, oil cooling system and pump.  Water flow was regulated by a swirl regulator (controllable valve) on the inlet side of the pump.  Marchwood has three pumps, two of which are required to operate to maintain maximum output of the station, with one on standby, due to the critical nature of the application.  The power station is required to be available and to respond to grid requirements at all times, so it was critical to remove any potential points of failure that might jeopardise this availability.

Marchwood was therefore seeking an more reliable system, but was also able to gain considerably more through the Siemens solution.

Increasing utilisation of plant and equipment

Siemens was able to provide an integrated drive systems (IDS) total engineered solution, which incorporated:

• distributed control system (DCS) modification
• supply and installation of three 2.5 MW 6.6 kV Perfect Harmony variable speed drives (VSD) with component failure bypass (cell bypass)
• supply and installation of three 2.1 MW 10-pole 6.6 kV vertically mounted AC induction motors complete with mechanical adaption bedplates
• supply and installation of an electrical equipment module (EEM), ie. a mobile switchroom to house all three VSDs
• supply and installation of all electrical power and control cabling requirements for the improvement upgrade
• removal from site of existing motors, gearboxes, oil cooling system and pumps
• new improved couplings for supporting reduced mechanical stress on the infrastructure during start-up
• full installation and commissioning of each of the new drive trains
• full site project management (complete turn-key solution).

The pumps at Marchwood were also removed and given a five-year overhaul.

This was a CS IDS total engineered solution from Siemens, with the associated benefits of greater reliability, extended availability and significant improvement to operational efficiency.  For Marchwood this meant lower running costs, better plant efficiency and a reduction in CO2 emissions, lowering the plant’s carbon footprint by over 2,000 tonnes per year.  Fundamentally, there was now less stress during start-up on the whole mechanical and electrical infrastructure.  Potential failure points had now been removed.

Scott Curtis is the Electrical Engineer at Marchwood Power and was the lead engineer on the project.  He commented: “We had a number of ongoing reliability issues associated with the pumps, motors and gearboxes of the main cooling water system.  These issues posed a significant risk to the commercial operation of our station.  Through a collaborative effort with Siemens DF and PD, we have successfully engineered out the problems that we were encountering and drastically improved the control and reliability of our cooling water system.  We are delighted with the results.“

Gary Palmer is the Siemens DF and PD Application Specialist for Large Drives Customer Services.  He confirmed that it was Siemens‘ knowledge and understanding of the application that would help benefit the Marchwood power station, now and into the future: “Using our Perfect Harmony variable speed drives in conjunction with our induction motors meant we were able to provide a truly integrated drive solution, from design through delivery of the installation and commisssioning; all from a single source of supply.  This is a great example of IDS in action, providing many long term benefits.“

The new system has been operating since October 2015 and figures have already shown improvements on the predicted energy savings.  The actual energy savings from this investment at Marchwood will be in excess of £150,000 per year.  CO2 reduction has also been predicted to drop by 2,100 tonnes over the next year, leading to additional cost savings. 

For Marchwood Power, the assurance of greater reliability with such high levels of availability have been the greatest benefits of the upgrade.

More on Siemens‘ integrated solutions for industry is available at www.siemens.co.uk

ENDS

For more information and photos please contact Bridget Summers on 01723 447424, email bridget@footprintpr.org.uk or Paul Addison on 07808 823346, email paul.addison@siemens.com

About Siemens

Siemens AG (Berlin and Munich) is a global technology powerhouse that has stood for engineering excellence, innovation, quality, reliability and internationality for more than 165 years. The company is active in more than 200 countries, focusing on the areas of electrification, automation and digitalisation. One of the world’s largest producers of energy-efficient, resource-saving technologies, Siemens is No.1 in offshore wind turbine construction, a leading supplier of gas and steam turbines for power generation, a major provider of power transmission solutions and a pioneer in infrastructure solutions as well as automation, drive and software solutions for industry. The company is also a leading provider of medical imaging equipment – such as computed tomography and magnetic resonance imaging systems – and a leader in laboratory diagnostics as well as clinical IT. In fiscal 2015, which ended on September 30, 2015, Siemens generated revenue of €75.6 billion and net income of €7.4 billion. At the end of September 2015, the company had around 348,000 employees worldwide. Further information is available on the internet at www.siemens.com