Protection of power systems with distributed sources

- Supervisor H. K. Høidalen, NTNU

Embedded or distributed generation (DG) will change the power flow in the system. This has strong impact on protection of distribution system, but also on the transmission level. In the distribution system, directional over-current or distance relays becomes required, and strict voltage and frequency protection have to be relaxed. In the transmission system, changes in power flow direction could pose challenges for backup protections. The project will consist of model and simulation of transients in power system to study the dynamic impact of distributed sources and how this would influence relay performance. The project will identify what data to communicate from distributed sources units and loads for optimum protection and fault location.

  • Distributed sensors
  • Communication of syncrophasor data from distributed sources
  • Algorithms for fault-location
  • Island detection and operation
  • Adaptive relaying

Wide-area protection and control using synchrophasors

- Supervisor Bruce A. Mork, Michigan Technological university (MTU)

Protective relays, transient event recorders, and dedicated PMU devices can provide and share synchrophasor data, essentially GPS time-tagged phasor measurement information. Usage thus far is more focused on slow-changing system operations or monitoring applications. Wide-area protection and control require higher speed real-time communications and several advancements in enabling technologies. The main issues to be addressed are:

  • Protective relay application in the context of: Interoperability issues, substation automation (IEC 61850), Grid system operations, SCADA, impact of high-penetration of renewable sources, energy management (EMS)
  • High-speed emergency control against power swings or voltage collapse.
  • Synchrophasor applications for unbalanced disturbances, for example single-pole tripping and reclosing.
  • Smart high-speed separation and optimal islanding when emergency control cannot hold the whole system together.
  • Operation of separated islands as micro-grids.

Smartgrid communication for protection purposes

- Supervisor Øivind Kure & Poul Heegaard, NTNU

The current protection systems, based on the IEC 61850 standard for substation automation, use link layer multicast. They rely on a homogenous communication system where one transmission reaches all possible recipient. The configuration is therefore simple. The Quality of service (QoS; delay, packet loss and delay jitter) is almost constant with no variation between different sources and receivers. Extending this beyond the substation (a single Ethernet) is challenging, since these assumption do no longer apply. The QoS will be heterogeneous and vary in both space and time. Distributed control, and distributed sources imply dynamic configuration of the flows of control and data. In a wide area multicast setting, there is always a trade-off between robustness, load, and reliability of packet delivery, delay and delay jitter. The challenge is to design network services with sufficient QoS for the new real time control algorithms that will scale beyond the substation. The cyber security aspects are important for multicast systems, which are vulnerable for misconfiguration, attacks and manipulation. In summary, the issues to be addressed are:

  • Optimal data management and availability to real-time distributed control processes.
  • Robust unicast and multicast architecture, protocols and services for the extended protection control system.
  • Dynamic configuration of multicast delivery adapted to distributed sources and dynamic protection algorithms.
  • Cybersecurity measures and their effect on real-time performance.
  • Evaluation of suitability of new commutations technologies like Software defined networking (SDN) in protection systems.

System integration and performance

- Supervisor Hans Kr. Høidalen & Bruce A. Mork

It is essential to confirm the functionality of an overall integrated system. The project will investigate beneficial system information structures and algorithms from centralized to distributed to combined hierarchical. Algorithms for optimal balance between performance and security will be developed. Data overload is occurring and the “big data” problem needs solutions.

  • Instrument transformers, sensors, transducers, and merging units
  • Data concentrators, protocol converters, and vector processors
  • Effects of time delays on wide-area performance
  • Algorithms centralized/distributed/hierarchical
  • Real-time computing performance (algorithms and data mining)
  • Correct power system protection and control performance – Security
  • Optimization of high-speed wide area control calculations
  • Synchrophasor bad data identification and state estimation