Concerns with global warming prompt governments throughout the world to pursue policies aiming at increasing renewable energy generation so as to reduce greenhouse gases produced by electricity generation from fossil fuels. However, due to the intermittent characteristics of renewable energy sources such as wind and solar power, it is a challenge for systems with large renewable generation capacities to achieve real-time balance between power generation and consumption, without which power instabilities and even blackouts may occur.

The key objective of this joint project by the University of Hong Kong, the Hong Kong University of Science and Technology, and the City University of Hong Kong is the integration of information technologies and electric power technologies to design innovative means to manage and control electricity generation and distribution networks. For example, Phasor Measurement Units (PMUs) may be deployed to better control a power grid with dynamic power generation. These devices sense the currents and voltages in real time, and provide data to the power grid operator for better and more reliable control of the system to avoid blackouts. Nonetheless, due to the high cost of PMUs and the limitations of communication facilities, it is impractical to deploy PMUs throughout the entire grid. Therefore, we have developed optimal PMU placement strategies to minimize the cost. We have also been studying a new concept called “electric springs” which may be used to achieve power balance. Electric appliances with electric springs embedded could be turned into a new generation of smart loads, with power demand following power generation. It is envisaged that electric springs, when distributed over the power grid, will offer another power system stability solution. Yet another possibility of accommodating highly volatile renewable generation is an energy storage system and we have developed an optimal control algorithm of a battery system for the grid-connected wind-storage system.

Smart grid laboratory to test the research results developed in the project

Customer participation may also help stabilize the grid. For example, differential pricing encourages customers to consume electricity when the demand is low, while demand response allows the grid to reduce the supply to selected customers (incentivized with reduced rates) when the demand is high. To facilitate such participation, an Advanced Metering Infrastructure (AMI) with real-time two-way communications and a smart meter deployed at each customer premise are required. Also, we must ensure network security and preserve customer privacy. Otherwise, an attacker may generate fake power requests, or even unauthorized control signals in the power grid. If a smart meter is compromised, an attacker may be able to determine which household has low electricity consumption, thereby inferring which customer is away from home and thus a target for burglary. In this connection, we have developed a secure power request scheme as well as a system in which users' private information such as daily electricity usage patterns is kept secret from third parties as well as from the power operator, while ensuring the power operator will be paid properly. Research results of this project will provide the foundation for further research on sustainable power delivery structures for high renewables.

Prof Victor On Kwok LI
Department of Electrical and
Electronic Engineering
The University of Hong Kong
vli@eee.hku.hk