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Harnessing biomass for stable, sustainable energy


The role of excitation systems in biomass generators N


early 5,000 active biomass power plants generate over 83 GW of electricity worldwide, with 1,000 more expected by 2033, according to ecoprog. Here Matthew Slater, director at generator excitation specialist Excitation & Engineering Services (EES), explores how brushless excitation systems help biomass plants maintain stable voltage, reduce maintenance needs and ensure reliable grid compliance amid this growth. Biomass power plants use organic feedstocks such as wood pellets, agricultural residues and forestry waste as fuel. These feedstocks combust in a boiler to generate high-pressure steam, driving a turbine connected to a synchronous generator. The turbine’s rotational energy is then converted into electrical power by the generator. These plants can operate as standalone power stations or in industrial cogeneration systems where electricity and thermal energy are produced.


Biomass generators face several challenges that directly impact their  Fluctuations in fuel, moisture content and energy density can impact combustion   stability.


Additionally, biomass combustion  and corrosive gases that can degrade  and reducing operational lifespan.


The importance of excitation systems


Excitation systems are crucial in addressing these challenges. By regulating generator voltage and providing reactive power support, they supply direct current (DC)   induces alternating current (AC) in the stator.   to maintain stable output.


A well-designed excitation system precisely controls the generator voltage, rapidly  sudden shifts without triggering instability and normally includes features like fault


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 ensures compliance with regulations like the UK’s Grid Code and the Connection and Use of System Code (CUSC) while minimising downtime and reducing maintenance needs in challenging conditions.


 to keep voltages within strict limits and provide reactive power to stabilise the grid,  network disturbances.


By stabilising the generator’s voltage and supporting reactive power, a well-maintained excitation system ensures consistent performance through regular servicing, calibration and testing. This reduces the impact of combustion instability, helping prolong the plant’s operational life and minimise downtime.


Biomass plants, typically smaller than  design and maintenance demands, for which brushless excitation systems are particularly suitable.


Unlike static excitation systems, which rely on additional components like brushes  systems are, by nature, more compact. Their smaller size allows direct integration into the generator eliminating the need for bulky external enclosures. With fewer moving parts and minimal maintenance, they offer improved reliability and reduced operational costs, ideal for smaller decentralised applications.


The role of brushless excitation systems


 exciter mounted directly on the generator shaft generates an AC supply, which is  windings. This design removes the need for brushes and commutators, components that are prone to wear and gathering carbon dust, common issues in static systems that can lead to reduced reliability. Brushless systems offer fast voltage regulation, essential for smaller plants that  compact, self-contained design makes them ideal for decentralised biomass stations where space and consistency are critical. EES provides bespoke brushless excitation system designs to enhance reliability and  for biomass plants in today’s rapidly growing and diversifying energy sector. The robust design, coupled with the company’s expertise in excitation systems, ensures plants can  performance and extend operational life, all  With another thousand biomass plants  and compliant operations are more critical than ever. Brushless excitation systems tackle fuel variability, reduce maintenance and ensure grid compliance, making choosing the right provider essential. Visit www. excitationengineering.co.uk/consultancy to discover how EES’s team can help your application.


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