Presentations

 

Future inertia needs from a system split perspective
Jorrit Bos | TenneT TSO B.V., the Netherlands

Abstract: The power system is changing rapidly. Inverter-based renewable energy sources, such as wind and solar PV, are replacing conventional fossil fuel-powered synchronous machines. This change affects, on one hand, the local system strength, and on the other hand, it causes inertia levels throughout the power system as a whole to decline. The decline in inertia levels is a clear trend that has been observed in recent years, and a further decline is projected for the future. To maintain the resilience of the power system, it is important to ensure sufficient inertia levels and a proper inertia distribution across the grid. Global system splits are the most severe events a large power system like the continental European system can encounter and are therefore used as a basis to determine the future inertia needs. ENTSO-E performed an extensive system split study (‘project inertia’) to define a minimum inertia threshold for continental Europe and to determine the future needs to keep the power system resilient. Within TenneT, the boundary conditions of this study were applied to national scenarios to determine what mitigation measures would be needed specifically for the Netherlands.

 

Use of data quality and other metadata for robust decision making in SIPS and WAMPAC schemes 
Oleg Bagleybter – General Electric Vernova, United Kingdom

Abstract: Advanced communication protocols such as IEC61850 and IEEE C37.118 have become ubiquitous in power systems. Among various other benefits, these protocols bring the concept of quality attributes associated with each signal. More specifically, IEC61850 signals include the detailed quality information, substitution/test/blocked flags, and a few others; while IEEE C37.118 adds to this list several attributes describing the synchronization status of the signal – whether the measured or streamed values are GPS-locked, how long it has been since the last locked sample, etc. IEDs also have their own data quality attributes, which are used in Wide Area Protection and Control (P&C) schemes. Where previously the associated applications could be blocked or disabled completely in case of issues such as loss of synchronization or invalidity of input parameters (either measured directly or received via communication channels), such approach is not acceptable anymore, especially with applications relying on multiple data sources distributed across a group of substations or even a whole grid (for example Wide Area Remedial Action Schemes).

For advanced SIPS/WAMPAC applications requiring accurate and timely measurements, there is a high probability that some inputs or processed signals may be missing at some point in time, while others might arrive marked as bad quality, unsynchronized, substituted, or with test/blocked flags. The paper presents a framework for dealing with such situations, which allows for maintaining both security and dependability of the application when the quality or availability of the input signals is degraded. The framework also covers scenarios where some parts of a large P&C scheme need to be independently tested or disabled, while keeping the rest of the functions operational.

The conventional solution to the challenges described above would be to carefully design and develop a separate piece of logic, which would sit on top of the core functional part of the P&C scheme to take care of the various combinations of the inputs’ metadata attributes. Such a solution is acceptable if the required P&C application has low complexity and/or relies on a small number of inputs. The paper will demonstrate that developing dedicated “quality-processing” logic schemes for complex applications with a large number of inputs is prohibitively time-consuming, which typically leads to blanket “all-or-nothing” solutions whereby any issues with the incoming signals disable the whole application.

The proposed approach relies on built-in metadata processing inside individual Functional Blocks (FBs) comprising the overall Protection and Control application. Examples of such FBs are logical gates (AND, OR), pick-up and drop-off timers, latches, thresholds, interpolators, buffers, and filters. Metadata-aware FBs will behave differently depending on the attributes of the incoming signals (such as validity/substitution/test/blocked, as well as synchronization status), assigning appropriate attributes to their outputs, which in turn will be processed by the downstream-connected FBs. The key differentiator of the proposed technique is that the correct behavior of a complex P&C application based on the inputs’ metadata is constructed “organically”, by relying on the embedded metadata processing of its constituent FBs and propagating the information between the FBs.

The paper will describe general principles of quality and other metadata processing and provide detailed examples of metadata-aware FBs. Real-life use cases will be presented as well, demonstrating the benefits of the proposed approach.

 

Addressing practical stability challenges of a transforming grid                      Douglas Wilson | General Electric Vernova, United Kingdom

Abstract: The complex stability challenges facing the electricity industry in its transition to zero carbon are difficult (perhaps impossible) to fully address by design and planning alone. Experience has shown that even with careful and conservative design of control, the complexity of interactions of the plant control system across the system is such that abnormal system conditions can arise that expose a risk of instability. The purposes of the emerging solutions in this presentation are:

1. To describe a core field infrastructure layer with components and architecture that can provide flexible capability for monitoring and control of stability issues. This includes a discussion on the boundaries of observability of synchrophasor measurements, and an approach to extend the observability across the range of possible interactions.
2. Applications for detecting, classifying, determining positive and negative contributions from plants or areas, and presenting the extracted oscillation behaviour to make the operator aware of the stability issue, and capture detailed information on normal and abnormal stability situations. Potential to change the system behaviour in real-time or a forecast period is discussed.
3. An approach to measuring and forecasting other key performance indicators, including the effective inertia and system strength of a typical area of a power system, is discussed, along with ways of making use of the indicators for practical mitigation of risk.
4. As well as the risk of unstable oscillations, areas of low inertia with large infeed losses are at risk of separation due to large, rapid changes in frequency and voltage phase angle shifts between centres of inertia. Wide area control arranged in network zones reduces the likelihood of separation, as well as improving its capability to ride through a separation without collapse.

 

European connection network code requirements 
Mario Ndreko | TenneT TSO GmbH, Germany

Abstract: European (EU) Connection Codes, usually termed as Connection Network Codes (CNCs) are a set of legally binding European regulations that describe technical requirements for the connection of electricity network users of all sizes to the electricity grid across Europe.  CNC, as part of the broader framework of European Network Codes, has been developed by ENTSO-E in collaboration with ACER (Agency for the Cooperation of Energy Regulators) and the European Commission. The CNCs aim to ensure harmonized grid connection requirements across EU Member States while at the same time leaving space for national and regional requirements to evolve, satisfying local systems' needs of relevant system operators. CNCs are the pillar to ensure secure and stable operation of the European power system, facilitate the integration of renewable energy sources, and support the development of a single European electricity market towards the energy transition.

The current CNC into force today (namely, network code for generators, demand, and HVDC – NC RfG, NC DC, and NC HVDC) have entered into force in 2016. The decarbonization of European electricity generation, demand, and the electrification of industry and mobility, which have been taking place in recent years, have created the urgency for the modernization of CNC to safeguard power system stability. On that aspect, ENTSO-E, as a key stakeholder in strong cooperation with the European Stakeholders under the umbrella of the Grid Connection EU stakeholder committee, has developed between 2021 – 2024 a set of amendment proposals for the CNC, termed as CNC 2.0.

This presentation will explain the key elements of the CNC 2.0 requirements. In addition, it will assess how these new requirements aim to support system stability and resilience of the EU power system with very high penetration of power electronic interfaced generation and demand. Finally, the presentation will conclude with a summary of recent work done by ENTSO-E and EU stakeholders on the development of detailed requirements for grid-forming capability of power park modules and electricity storage systems.

 

Grid-forming converter application - a necessity for the future 
Wilhelm Winter | TenneT TSO GmbH, Germany / TU Delft, the Netherlands

Abstract: Technical analyses conducted by various European transmission system operators (TSOs) project a substantial reduction in grid-forming capabilities and system inertia post-2030. This trend is primarily attributed to the increased integration of power electronic interfaced generation units and a concurrent decline in synchronous power generation. Consequently, TSOs must implement measures to safeguard future power system stability. One extensively discussed and promising strategy is the incorporation of assets with grid-forming capabilities (GFC) into the transmission network. Such assets can deliver essential grid services—such as inertia provision and voltage formation—to help stabilize the electricity grid during critical periods. In Germany, a supplement to the VDE-AR-N 4131 standard for HVDC systems and DC-connected power park modules, published as an FNN guideline, specifies an exemplary method for grid-forming compliance procedures. The presentation shows the urgent need for grid-forming capabilities for securing power system dominated power systems.

 

Interarea oscillations in the European continental power system - challenges and damping measures                                                                                                   Walter Sattinger | Germany 

Abstract: The presentation refers to a short history of the European power system extension steps. It will elaborate on the mechanism of Inter-Area Oscillation occurrence and related damping measures. This presentation will also present some examples of critical Inter-Area oscillations that have been investigated so far, and will be supported by conclusions and possible plans for further developments.

 

Experience with Sub-Synchronous Oscillations (SSO) in transmission grids    Klaus Boehme | Siemens AG, Germany

Abstract: The presentation will elaborate on the recent experience and solutions that Siemens proposes for how to deal with an increased level of SSOs.