Grid-Supportive Power Electronics for Power System Security

Lead Research Organisation: Imperial College London
Department Name: Electrical and Electronic Engineering

Abstract

Ensuring system security and stability is an ever-present concern in power system engineering due to the crucial importance of reliable power supply in modern society. The growth of renewable energy increases the number of power electronic converters present in the power network since they are needed to interface non-conventional forms of generation to standard 50 or 60 Hz system. This changes the network's physical structure and causes new threats to security. Compared to conventional power equipment, power electronic converters are subject to rigid capacity constraints which make them prone to lose functionalities during large disturbances and trigger fault cascading. On the other hand, converters have higher flexibility and faster response which enable more versatile patterns of dynamic control. Therefore, a new methodology for both converter design and system operation is needed to take advantage of the strengths and mitigate the weaknesses of converters in supporting grid security.
This problem is difficult because power electronic converters have sophisticated internal dynamics which further interact with a complex power network with a vast number of nodes and uncertain disturbance scenarios. What adds to the difficulty is that converters and networks are created by very different owners and supply chains that newly come together but still have different perspectives and technical languages. This fellowship aims to establish a common technology framework for converter manufacturers and network operators, and find a systematic methodology and practical tools for grid-supportive converter design and converter-based grid security management.
The proposed research sets out to do three things. First, it will find analytical methods to quantify the support provided by and stress placed on converters regarding network security, from which converter design guidelines will be derived to optimize the security support functions in a cost-effective way. Second, it will build computational platforms for network operators to use a vast number of converters synergistically for real-time security management. Third, it will develop proof-of-concept prototypes, demonstrate their application potential in a complex power system, and promote commercialization and standardization.

Planned Impact

The growth of renewable energy sources in the power system greatly widens the use of power electronic converters for energy processing and routing, which changes the physical nature of the power system and brings about new security threats. Converter-induced security incidents are reported worldwide which draw attention from both academia and industry. The fellowship addresses this timely topic and aims to establish a common technology framework for converter manufacturers and network operators with respect to power system security to the benefit of a wide range of stakeholders in the industry.
(1) Converter Manufacturers:
The design methodologies for power electronic converters keep evolving amid their growing penetration in the power system. However, the development cycle of a new generation of products usually takes more than 3 years, so converter manufacturers are keen to take a future-oriented perspective in product design to keep their technologies in pace with the macro trend. This fellowship will help manufacturers establish guidelines on next-generation product design to meet future security requirements and provide extra security services in the most cost-effective way.
(2) Network Operators:
As pointed out in the "Smart Systems and Flexibility" strategy of the UK government, finding and exploiting flexibility in the electricity network is a critical pathway to the decarbonisation of the electric power sector. This research will explore new operation patterns for network operators to use converters as an important source of flexibility in network security management. It helps to eliminate the bottleneck of transient stability in power transmission and distribution, and therefore enables more efficient use of network capacity and avoid the extra investments on network reinforcement.
(3) Standardization:
As the power network is an open system accommodating facilities from different suppliers, establishing a common consensus via standardization is the most reasonable way to ensure security and scalability simultaneously. Grid standards are issued by power system operators considering the suggestions of all stakeholders including owners and manufacturers of generation, network and load equipment and may be further authorized by national legislation and regulation. This fellowship will make recommendations on future grid standards emphasising the role of grid-supportive power electronics in network security, via the channels of SOF and CIGRE.

Publications

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Description The research discovered the completeness of impedance/admittance models in power system stability analysis.
The research established a unified cross-domain modelling methodology for composite power systems.
Exploitation Route The finding set the basis for future grid codes/standards.
The findings set the basis for power system analysis software design.
Sectors Energy