Power Quality Metering / Monitoring Solutions

Electrical power runs almost every machinery in the world. As clean unadulterated food is important for the healthy lifestyle of human beings, machines need clean power for longevity and uninterrupted operations. Therefore, high-quality power is absolutely required for the successful operation of the factories and the buildings. IEEE 1159 standard defines the international standard for clean power by limiting the maximum limits allowed for over/under voltage/current conditions, Sag/Swell, poor grounding/earthing, level of different current and voltage harmonics, etc. Power distribution companies maintain this standard while feeding to the transformers at the input to the factories and the buildings. However, power distribution inside the factory or the building may not comply with IEEE 1159 standards since within the factories/buildings power quality degrades due to uneven tapping of single-phase load from 3-phase lines, DC loads like LEDs, UPS, Mobile/Laptop charges, etc. Poor quality is not only responsible for immature death/downtime of the machines/controllers, it also threatens basic fire safety issues since power surges or imbalance may lead to the burning of the wires. In addition, harmonic contents of the power are normally wasted and thus contribute to energy inefficiencies.

Power Quality Meters have wide range of applications - most notable among them are:

• Check the compliance with IEEE 1159 power standards to make sure Power fed to the factories/buildings/machines are clean.
• Additional algorithms available to monitor predictive health of the Motors, Heaters, Drives 24x7 continuously in the cloud and in the edge system.
• Compare energy usages between different machines within a factory.
• Calculate the utilization and productivity of the machines.
• Measure energy usage per unit of productivity.
• Estimate the actual cost of electricity by an accurate cost model of energy usage that depends on time of the day, time of the year, etc.
• Capture surge or small duration electrical event in detail using the event capture mechanism.

Power Quality analyzer has one hardware and 4 software components.

• Its hardware captures the voltage and current data of a machine or electrical line. Its hardware supports up to 6.6 kV and 0-4000A range.
• Voltage, Current and Power Factor data then fed to sensor system software ( Software-1) which extracts all the useful information ( metadata) of power quality ( harmonics, over-voltage, RMS, etc.) in real-time and with a sampling rate required for the application
• Then power quality metadata is ingested into an analytic module ( Software-2) which does analytical modeling for power quality. All the metadata and analytic results are continually stored into a database system ( Software-3) which stores the data for 6 months. In MachineSense system, Software 2 and 3 can be deployed both locally within the factory ( edge cloud) as well as in the public cloud ( MachineSense offers a fully-featured SaaS for that).
• Final results of analytics, metadata and database can be displayed/accessed using two different visualization software systems ( Software-4). One type of visualization known as data monitor is for plant engineers /maintenance crew. This version of visualization is fully automated. Another type of visualization is for expert electrical engineers which allows the engineers to play with data and algorithms in an open platform.

IEEE 1159 -1995 defines the power quality issues that have to be monitored in any Industrial or commercial operation. This includes approximately 37 different kinds of issues but overwhelmingly only a handful of them occur frequently in any manufacturing or building set-up.  Most common occurring issues in power quality are:

• Current harmonics: Source of harmonics in current lines can be a number of device installation in the distribution line.  Current Harmonics are generated when

1. a non-linear load like a DC load ( battery charger, LED) are connected to the line
2. Current imbalance also generate harmonics
3. AC drives, UPS throws up a lot of harmonics back to the line. Harmonics are unwanted current frequencies and the heat up the motor coils. Thus, if compressors, HVAC, fans are failing frequently, it is a sure sign that harmonics in the line have exceeded alarmingly. The safety limit of total current harmonic distortion (THD) is around 5-7%.

• Poor grounding/earthing: The transmission line is also a good antenna. In order for electronics ( like router, laptop charger, printer) to work well in a factory, office or home, unwanted radio frequencies ( in the era of WiFi, 4G/5G, there are tons of them ) that are absorbed in all the lines and polluting the electronics signal as noise must be pushed back to ground or earth. Lightening also throws out some of the strong RF bursts into the lines. All of this must be safely passed to earth via earthing wire.  But earthing of most buildings is very poor and hardly anyone keeps track of cleaning and maintaining them. Especially if earthing is in a river valley which is dominated by alluvial clay and receives rain, the earthing chemical inside the ground will be washed out very quickly within months.
• Surge:  Voltage or current surge is also common in any factory/building. Surge can destroy the controllers and electronics of machines.  The source of the current surge is inrush current.  When adjacent heavy machinery is switched on or off, all of a sudden a big load is increased or decreased momentarily. This adds to milli-second duration surge in voltage or current that can be seen by machines on the same line. This can also happen if an adjacent factory is switching on/off a big load. 
• Voltage and Current imbalance: Voltage and current imbalance in a three-phase AC line can be very dangerous to machines as well as for fire safety. Unbalanced current will be passing through a neutral wire and as a result of high neutral current, the wire can burn and can be a source of the fire. In India, studies conducted by MachineSense shows most of the fire is caused by this.  This kind of imbalance happens because of uneven tapping of single-phase from 3 phase currents.

Poor power quality may lead to a fire in many ways and is responsible for 85% of the fire in the buildings.

• In India and many Asian countries that have a neutral wire, the most common source of electrical fire is the flow of very high neutral current. High neutral current is a result of current imbalance and harmonics. A neutral wire is vulnerable to fire because by standard this wire is thinner ( supposed to carry lower currents) and does not have circuit breakers
• Motor coil burns due to high harmonics
• If there is poor grounding/earthing, any kind of lightning surge can lead to a fire.

All kinds of equipment barring old-style Tungsten lamps are prone to damage due to power quality.

1. Any machine that uses a Motor ( 65% machines use a motor at least) like Pump, Compressors, Fans – will face premature death due to burning of the coil from harmonics
2. Any heavy machine depending on large or small magnet like MRI, CT Scan also gets damaged from Harmonics and imbalance
3. Robotics depend a lot on actuators and solenoids - they also get burned quickly
4. Servers get a reduced life-span because their fans don’t work properly
5. Air Conditioning equipment like chiller, HVAC are highly power quality sensitive.

There are several power quality standards but IEEE 1159 is the most commonly followed standard worldwide. IEEE 1159-2019 is the latest which has superseded 1159-2009. For more details, please check 

https://standards.ieee.org/standard/1159-2019.html

The following developments in the power sector played a tremendous role on power quality:

1. Energy Improvement/Efficiency Measures generating more Harmonics in the lines than before ( https://ieeexplore.ieee.org/document/7853241).  Energy-saving measures like a replacement to LED, AC drives are a major source of harmonics pollution in the line.
2. Growth of microgrids & renewable energy sources (like solar) adding bad quality power in the grids (https://ieeexplore.ieee.org/document/7738432). Solar plants and its inverters are one of the largest sources of harmonic pollution.
3. Rise of battery for mobile chargers, electrical vehicle chargers and inverters led to further rise in the non-linear loads which add a lot of harmonics (https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8378374)

Total loss of United States GDP due to 1,2,3 are more than $45.7B a year (https://energycollection.us/Energy-Reliability/Cost-Power-Disturbances.pdf). However, the problem of power quality is very often ignored since it is not monitored. Most of the time end-users get aware of it only when they see frequent breakdowns of the machines or fire coming out of the wires. Waiting for such a long time to know the building has poor power quality is dangerous for the safety of the inhabitants of the buildings as well as utility machines.

The solution to Power Quality problems that have resulted from 1,2,3 are well recorded and recommended in ISA ( International Society of Automation: https://www.isa.org/about-isa/ ). However, to provide ISA compliant clean power to every building and plant, that are already suffering from poor power quality (1-3), one needs a system that:

1. Collects the power quality data (such as voltage & current imbalance) from every important point of the distribution ( which is powering very important and costly machines like HVAC or Compressors, after the incoming transformer, etc. )
2. Analyzes the data statistically ( since power quality data will change with the days - weekdays vs weekend, day vs night, office time vs vacation time)  and a power quality expert, who is well versed with solution engineering and can design appropriate UPS, harmonic filter, etc. required to meet ISA standard for power quality.

The commercial challenge for 1 includes cost-effective hardware and cloud platform ( IoT or Cyber-Physical System ) that is affordable by building and plant management.  That problem has been solved by MachineSense LLC by using state of the art System on Chips ( SoC), single-board computer like Raspberry Pi and Open Sourced software.

However, the commercial challenge for 2 is far more difficult and critical. As shown in the paper (https://cdn.selinc.com/assets/Literature/Publications/Technical%20Papers/6303_TodaysEngineeringShortage_JP_20071026_Web.pdf?v=20151202-215825), the US now produces only 500 engineers ( reduced from 2000)  annually who are capable of such power diagnosis. There are hardly 50,000 power engineers active in the US. It is impossible for 50,000 engineers to address the power quality issues of 13M US buildings ( office, hospitals, plants, etc. )  even if all data to solve the problems are available. 

Power Quality Analyzers had a wide range of applications - most notable among them are:

1. Check the compliance with IEEE 1159 power standards to make sure power fed to the factories/buildings/machines are clean
2. Additional algorithms available to monitor predictive health of the Motors, Heaters, Drives 24x7 continuously in the cloud and in the edge system. 
3. Compare energy usages between different machines within a factory 
4.  Calculate the utilization and productivity of the machines  
5. Measure  energy usage per unit of productivity 
6. Estimate the actual cost of electricity by an accurate cost model of energy usage that depends on the time of the day, time of the year, etc. 
7. Capture surge or small duration electrical event in detail using the event capture mechanism.