Power plants supply the city’s electrical needs using alternating current (AC) power transmission. In AC power transmission, electrical energy is distributed by generating an AC voltage waveform (usually a sine wave) with a frequency of 50 or 60 Hz. This waveform is then distributed over the city’s grid via power lines. The power plant generates three sine waves with phases spread apart by 120°. On a city scale, power transformers introduce additional phase shifts to these three phases. Each power consumer within the city, from street lamps to household power outlets, connects to ones of these three phases, arbitrarily. Several problems arise in the context of city-wide power distribution:
i) Inferring grid phase state: Ideally, the total electrical load of the city should be balanced over the three grid phases. With this goal in mind, engineers connect different power consumers to one of the three phases. However, on a city scale, there exists no clear and complete documentation about such consumer-to-phase connections. This information is nevertheless in great demand for discovering unbalanced power consumption within the city, discovering power transmission problems within the city and more.
ii) Harmonics detection: Industrial power consumers, such as plants, may have facilities that consume power from the grid in a way that disturbs and corrupts it (introducing harmonics to AC sine wave). There are regulations in place that limit the allowable amount of such disturbances, per consumer. Officials have no way to discover whether a plant violates the regulations without entering plant grounds and physically measuring its power consumption.
iii) Special facilities detection: Discovering special interest power consumers is difficult to achieve remotely.
We propose a novel way to recover electric grid properties efficiently to recover scene information remotely, for thousands of grid elements at once.
- The method enables recovering network properties in thousands of location around the city, remotely, just by point a camera at the desired region, all in a fraction of the cost of a single PMU.
- Not limited to city scale scenes but works on any scale: from a room lit by few lamps, through a street lit by several dozen indoor and outdoor lights, to the city-wide scenes.
Applications and Opportunities
- Passive and remote inference of grid phases for bulbs connected the AC grid over a large area.
- Passive and remote detection of harmonics distortions introduced by industrial power consumers.
- Passive and remote detection of consumers with unique power consumption signature.
- Graphics applications including: simulating how a scene would appear under different lighting type.
- Digital camera white-balancing in difficult scenes, lit by several different lamps.
- Remote identification of bulb types.
- Remote classification of flicker type and intensity. AC bulb flicker has shown to have adverse effects on certain individuals.
- Detection of grid interference propagation within throughout electric grid.