  Digitalization enables the automation required to operate modern
cyber-physical energy systems (CPESs), leading to a shift from hierarchical to
organic systems. However, digitalization increases the number of factors
affecting the state of a CPES (e.g., software bugs and cyber threats). In
addition to established factors like functional correctness, others like
security become relevant but are yet to be integrated into an operational
viewpoint, i.e. a holistic perspective on the system state. Trust in organic
computing is an approach to gain a holistic view of the state of systems. It
consists of several facets (e.g., functional correctness, security, and
reliability), which can be used to assess the state of CPES. Therefore, a trust
assessment on all levels can contribute to a coherent state assessment. This
paper focuses on the trust in ICT-enabled grid services in a CPES. These are
essential for operating the CPES, and their performance relies on various data
aspects like availability, timeliness, and correctness. This paper proposes to
assess the trust in involved components and data to estimate data correctness,
which is crucial for grid services. The assessment is presented considering two
exemplary grid services, namely state estimation and coordinated voltage
control. Furthermore, the interpretation of different trust facets is also
discussed.
