Sources of oscillations on the transmission system can be determined by investigating the transfer of oscillation energy in the network. Following the direction of the energy flow on the system allows the source of the oscillations to be traced.
These methods have limitations: it requires good coverage of power management units (PMUs) across the system, determining the time period for calculating the energy flow requires some manual intervention and some oscillation source will absorb energy at certain frequencies, meaning that the energy method cannot be used.
This project aims to explore potential improvements to energy methods, investigating the application of signal processing techniques to improve accuracy with limited PMU coverage, remove the need for manual intervention and to replace the energy flow direction calculation.
Benefits
The project outcomes aims to enable NESO to accurately and actively identify sources of oscillations in real time. By making use of limited PMU coverage, the project will locate oscillation sources and reduce the need for additional PMU installations. It will also reduce reliance on stakeholder data to locate these sources. Furthermore, the project aims improve the accuracy and reliability of location methods through the use of advanced data processing techniques.
Learnings
Outcomes
1. New PMU trilateration method that reduced the number of required PMUs in oscillation source localisation by more than 70% in the considered cases.
2. New energy method that calculated the mode of interest and its arrival and departure times in the wavelet domain to enhance the accuracy of the conventional energy method from 10% to 67% in the considered cases.
3. New wavelet method that used the wavelet energy to enhance the accuracy of the conventional energy method from 10% to 95% in the considered cases.
4. Five deliverable reports and associated MATLAB programming codes detailing the designs and software implementation of these new methods.
5. Three publications to increase the impact of the innovation.
Lessons Learnt
Managerial:
1. It was useful to engage with the stakeholder as soon and as frequently as possible to keep the direction of innovation on the right track, for example, to make the simulation settings close to reality.
2. It would be useful to have the university research admin support and other relevant staff in the project meetings to understand their admin procedures better for reduced delays.
Technical:
1. The impedance-based PMU trilateration method requires power system topology information but in some situations this may be difficult to acquire, as the topology may dynamically change. For future projects, this method could be improved by using machine learning algorithms, such as reinforcement learning, to adapt the method to different environments.
2. Some of the data from the ISO New England test case library may have issues, such as Case 5. For future projects, data pre-processing may be adopted to check the quality of data before applying them to the oscillation source localisation methods.