Smart solutions to
energy efficiency

In an office building in Kowloon Bay, there is a meeting room that looks just like any other in Hong Kong but is actually unique. It is powered purely by Direct Current (DC) electricity, which minimises the number of power conversion stages and reduces the amount of power loss by between 50% and 78% compared with existing Alternating Current (AC) technology.
This is ASTRI’s Next-Generation Energy-Saving Solution for a Smart City, an emerging application aiming for a high degree of energy efficiency. The idea is to power a home or building by DC instead of AC, bringing significant power savings.

It is being trialed at the headquarters of the Electrical and Mechanical Services Department (EMSD), a key partner for ASTRI in creating this impactful technology.

EMSD Senior Building Services Engineer (Acting) Winson Wong says: “The EMSD aims to promote and facilitate I&T solutions by providing suitable venues for trials by working with I&T solution partners in the market. It has been a great experience in collaborating with ASTRI to conduct a trial in one of our meeting rooms for DC application.”

Adopting new green technologies to reduce buildings’ energy usage is an essential element of a smart city. Power plants that rely on renewable energy sources, such as solar, produce DC power. DC power is also widely adopted in low-voltage applications, including personal electronic devices, home appliances, battery energy storage systems, e-mobility and computing.

Energy Efficient Direct Power Distribution System

Although direct use of DC power can reduce the loss in
general, failure is more serious than AC. For instance, the short circuit current will keep increasing and in a faster rate in DC than AC. Due to the fact that AC voltage is bipolar the short-circuit current will increase when the voltage is positive and reduce in negative. However, DC provides a
constant positive voltage so that the short-circuit current will only increase. Therefore, a DC breaker with a fast detection and disconnection ability is highly important to ensure safety.

ASTRI’s innovative solution provides an ultra-fast solid-state DC circuit breaker enabling micro-second range protection in case of a failure. It is 100 to 1,000 times faster than circuit-breaking devices currently available. It ensures the safe use of DC power, allowing us to make the most of its energy efficiency.

Advanced technologies including a Silicon-carbide (SiC) based efficient power conversion solution, ultra-fast DC protection devices, real-time monitoring and online capacitor preventive maintenance will be developed in this project. Back to that unique meeting room at the EMSD headquarters, powered by ASTRI’s DC technology. While its construction is still in progress for now, ASTRI is looking forward and will focus on developing an Energy Router and Intelligent DC circuit breaker with a fault identification function to make the use of DC power safer, allowing for its much wider roll-out across Hong Kong.