Frequency stability contribution of combustion engines

Investigation of requirements and impacts for balancing products in future power systems

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Martijn Duvoort Martijn Duvoort
Director Energy Markets
Frequency restoration reserve

Wärtsilä Finland Oy

Worldwide, the power system is changing profoundly. The integration of renewable energy sources is advancing rapidly, and while the environmental benefits of these sources are obvious, the intermittency and unpredictability of their power output pose challenges for grid stability, especially for system frequency. This is enhanced by the fact that renewable sources are not always able to contribute to frequency control services and system inertia and are replacing power plants that were contributing to those services. This also increases the vulnerability of the system during disturbances such as power plant trips. Frequency stability is therefore becoming a prominent issue in the power systems of the future.

To explore future strategic options for their business, Wärtsilä Finland Oy, a manufacturer of reciprocating engines, wanted to investigate the impact of balancing product specifications in a representative future (European) power system with a high share of renewables. What are the best specifications for their products, now and in future scenarios, to enable Wärtsilä’s customers to provide frequency restoration reserve (FRR) to contribute effectively to frequency and thus system stability.

DNV GL investigated whether an adequate frequency response would be achieved with varying requirements for the provision of frequency restoration reserve (FRR). The impact of changing reserve ramp rates, FRR capacities and the ratio of spinning to non-spinning reserve on system stability was simulated using DNV GL’s proprietary simulation tool, KERMIT.

The assessment was carried out for both merit-order and pro-rata activation schemes. Via another model the economic consequences of keeping these required FRR resources available were investigated.

DNV GL’s report presents the results of a study performed to investigate the requirements for and impacts of properties and specifications for balancing products for frequency restoration reserves (FRR) in a representative future power system. Via an economic model the economic consequences of the required resources were investigated.

The project services contained an in-depth investigation into the technical requirements of balancing products for frequency restoration and the economic consequences of keeping the required resources available. DNV GL’s methodology and the findings of the study were presented to Wärtsilä Finland Oy.

Value to the client
Wärtsilä Finland Oy uses the report to determine the applicability of fast reserve generators in a European power system with high shares of renewables. The report shows when and how combustion engines can support the current and future power system (including a high degree of renewable generation sources) to mitigate some of the challenges posed by higher amounts of renewable electricity generation.