Innovative Solutions for Combine Heat & Power Plants Frequency Support Services

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Sweden is a good example of how the energy system has transformed from steady baseload production to a more weather depending production with less base load production. The hydroelectric plants have worked as a quick and reliable balancer in the system to ensure a steady 50 Hz frequency.  Today the system requires higher flexibility with even faster reaction times than the hydro electric plants can offer.

To support the stability in the electricity system, “Svenska kraftnät” has introduced several different support functions.

  • FFR
    • Part of remedial measures and is activated in the event of transient frequency drops to prevent the power system from falling outside the specified operational safety limits.
    • Full activation within 1.3 seconds in the event of a frequency drop to 49.7 Hz.
    • Full activation within 1.0 seconds in the event of a frequency drop to 49.6 Hz.
    • Full activation within 0.7 seconds in the event of a frequency drop to 49.5 Hz.
  • FCR-N
    • Frequency-related support service. Its task is to manage normal frequency variations in the power system.
    • Automatic linear activation when the frequency deviates from 50 Hz and full activation within 180 seconds when the frequency deviates by +/- 0.1 Hz from 50 Hz.
  • FCR-D
    • Frequency-related support service. Responsible for handling frequency deviations during disrupted operation.
    • Automatic linear activation within the frequency range 49.9 – 49.5 Hz for upregulation and 50.1 – 50.5 Hz for downregulation.
    • Full activation within 30 seconds when the frequency falls below 49.9 Hz.
  • aFRR
    • Frequency-related support service. Its task is to relieve activated FCR-N and FCR-D.
    • Automatic linear activation when the frequency deviates from 50 Hz and full activation within 300 seconds (5 minutes).
  • mFRR
    • Frequency-related support service that relieves the automatic support services. In addition to balancing the power system, it is primarily used to manage disturbances and overloads in the transmission network.
    • Full activation within 15 minutes of being engaged.

For a district heating plant with capability to produce electricity this is a welcome contribution to the financial revenue. The market in Sweden is currently 3-3,5 billion SEK and expect to increase.

Above: Table for frequency support sevice in Sweden.

Technical Solution

To be qualified for the frequency support services, the plant must technically be prepared. This basically mean that the production of electricity shall start or stop very rapidly, within minutes. Since the energy media is steam, all components I the steam system must be prepared for a higher flexibility. The most critical component is the Turbine bypass valve. It is often located in parallel with steam turbine feeding the district heating direct condenser.

BVT-TB designed with extended rangeability is a control valve system prepared for the highest available requirements on the market today.

  • High rangeability through dual cooling injection systems.
  • Best low flow capabilities on the market
  • Combine the advantages of spring-loaded spray nozzles with steam assisted nozzles.
  • Fully forged valve-body, produced in Sweden.

Summar

BVT Sweden is proud to offer CHP/district heating plants our innovative solutions. With BVT Sweden’s groundbreaking technology, CHP/district heating plants can not only meet the stringent technical requirements for frequency support services but also maximize their financial revenues, reduce their emissions, and contribute to a more stable and flexible energy supply. Our solutions are designed to meet the highest market demands today, and we are dedicated to helping our customers achieve their goals and exceed their expectations. Together, we create a sustainable future.

Facts

BVT Sweden, based in Säffle, develops and manufactures world-leading valves for power plants worldwide. Their newly developed, unique solution for temperature control at minimal flows has been successfully implemented in several district heating plants. The Swedish company’s locally produced high-tech products ensure extra competitive pricing, quality, and short delivery times. BVT designs and manufactures complete control systems and also offers comprehensive solutions with installation, pipe calculations, and system design.