Digital circuitry surrounds us, embedded in all kinds of digital equipment including phones, computers and industrial facilities. These highly sensitive electronics have revolutionized our era, running everything in our daily lives from our digital economy to manufacturing processes. However, this explosive growth also triggered a new cascade of demands on power companies to provide a more reliable and high-quality electrical power supply.
Maintaining adequate power quality for their customers is today‘s utilities top challenge. As a former power quality engineer at a Mid-Atlantic U.S. utility, I investigated and witnessed many cases where a transient voltage sag for instance, would shut down an entire assembly line and manufacturing process. In most instances, it could take the manufacturer 4 to 8 hours to get their operations back up, costing the company time and revenue. I also experienced the struggles and pressure my colleagues and I had to go through to rapidly troubleshoot the causes and sources of the power quality problem spending valuable time and resources across departments.
In this blog, I will discuss the methodologies currently used by power engineers to investigate and troubleshoot those power quality issues, as well as, a new, innovative approach used by two large utilities in the U.S. that could transform the way we investigate these problems in the future.
What is Power Quality (PQ) and why is it important?
The Institute of Electrical and Electronic Engineers (IEEE) defines power quality as:
“The concept of powering and grounding sensitive equipment in a matter that is suitable to the operation of that equipment.”
Bottom line is, Power Quality (PQ) problems are a central topic to today’s smart grid design and operations because, without a good and continuous voltage supply to electronic devices, it may cause malfunction, damage equipment and even disrupt industrial/commercial operations.
According to a report by Onpower, U.S businesses are losing up to $24 Billion each year because of power quality issues. If unable to obtain high quality of electrical power, those companies could be forced to move and continue their operations to areas better suited for their activities, further pressurizing utilities to maintain adequate power quality.
How do we investigate Power Quality problems?
As a power quality engineer, I received numerous trouble tickets every week from customers with power quality issues that had to be investigated and resolved. Most power qualities issues are called-in by customers and identified as:
- Flickering lights
- Equipment failure
- Assembly line/process malfunctions for industrial customers
Investigating power quality problems has usually been an “after the fact” struggle for utility engineers. While they have access to a vast array of instruments to evaluate the cause of disturbances, the methods have not changed. These methods are often very time consuming, create inconveniences to customers and require the coordination and resources from multiple departments.
The long and more established method to identify PQ issues for commercial clients is to install a power quality or recording voltmeter at the customer’s facility. For larger commercial and industrial customers, this often requires significant coordination between the meter installer and the customer. The meters are typically installed inside a medium or low voltage switchgear on the customer’s property and on most occasions requires a temporary outage to safely install the recording equipment disrupting their operations.
For residential issues, several recording voltmeters are typically installed at the meter base of the homes in the area to try to localize the source of the problem. Once a general direction is determined, the recording voltmeters are moved to different homes until the source of the problem is identified. This method can take many weeks of efforts and create disruptions to residential customers.
What are the new techniques to investigate Power Quality issues?
In this next part of the blog, I will discuss how two utilities decided to undertake a complete different approach to identify their PQ issues by installing Smart Grid Sensors. This innovative approach allowed them to quickly pinpoint the cause of the problems and save a significant amount of operations and maintenance costs by leveraging the advanced capabilities of this technology.
Two Inspiring Examples of Smart Grid Sensors Users Experiences
Case#1: Flickering Lights
A utility in the northeast portion of the U.S received complaints of flickering lights affecting hundreds of customers’ homes all on the same 4.8kV circuit. As per procedure, the utility engineers first started their investigation by completing a thorough line patrol and then verifying that all of their equipment on the lines was in working order. With no results and not knowing where to start, the next available option was to spend the next few weeks installing recording voltmeters at several of the houses in the area. They would then have to continuously drive back to these locations to collect and download the recorded data hoping something would show the cause of the problem.
Instead, they decided to take a different approach and utilize the capabilities of the LightHouse Smart Grid Sensors which they already had to see what they could find.
The power quality engineer instructed their lineman to install the sensors on a section of line upstream of all of the complaints. Once on site, it took the lineman less than 15 minutes to install the sensors. Hours after the installation, the Smart Grid Sensors identified both the location and cause of the problem.
A nearby factory had recently installed a 40hp motor that did not have any reduced voltage starting or other soft start capabilities and started about 5 times per hour. This new installation created an excessive amount of inrush current every time the motor started as shown on the graph.
What the LightHouse Sensors discovered.
The sensors accurately recorded each time inrush current was present on the line as shown on the chart, and instantly delivered the data to the power quality engineer in charge of the investigation. With this data in hand, the utility was able to approach the factory supervisors with the evidence provided by the smart sensors.
Because of the engineer’s quick thinking and the sensors capabilities:
- The factory recognized the need to install additional equipment to mitigate the impact on the distribution system in the area, which resolved the flicker light problem. The factory didn’t realize they were causing any problems because the flicker was only visible in incandescent lighting and the factory only had fluorescent lighting.
- The engineer in charge was able to complete his investigation in just a few days when it would have taken him weeks using more traditional methods.
By installing Smart Grid Sensors on their circuit, the utility company was able to 1) close their investigation much faster 2) put a quicker end to customer’s frustration, 3) drastically reduce the amount of time and resources it would have taken using more traditional methods of investigation.
Case #2: Equipment Malfunction
Variable Frequency Drives (VFDs) are commonly used on small appliances, large motors or even compressors to control the motor speed and torque of a device. A large industrial manufacturer took notice that while the voltages on their motors were very balanced, one of its VFDs would trip out on unbalanced current. They decided to reach out to their local utility to help them resolve the issue suspecting an anomaly on the power system.
After several meetings to try and identify the cause of the VFD malfunction, the utility company determined that the best course of action to investigate this issue was to set-up a recording voltmeter inside the 480 volt switchgear at the site to measure the voltage and current over the next several weeks. In order to complete this installation and be able to download the data from the recorder before it ran out of memory, each week the utility engineer would have to de-energized the switchgear costing the manufacturer thousands of dollars in revenue each time the equipment would be powered down.
Unable to use more conventional methods to conduct their investigation the utility company turned to Tollgrade for a solution. They wanted to be able to constantly measure the power quality of this particular customer without requiring an outage.
What the LightHouse Sensors uncovered.
The LigthHouse sensors were installed directly on the 12.47kV tap into the customer’s substation and started delivering data to the utility engineers immediately. With data in hand, the utility was able to conclude and present their findings to the customer that there were no abnormalities on the power system when the VFD gave the error messages.
By utilizing LightHouse sensor technology:
- The customer was able to narrow down the cause of their issue and refocus their attention to finding the source of the problem inside their facility.
- The engineer never had to go to the customer’s site since all the data was delivered automatically through the LightHouse SMS application that they accessed from their office.
- Not only was the utility able to avoid disrupting the manufacturer’s activities, but also eliminated the trouble for the engineer to schedule an appointment each week and wait for an escort at the facility to retrieve the data.
- The utility was able to better manage the limited resources of the metering department by using equipment that could be installed by a lineman using standard work methods.
In this example, the use of an innovative technology like smart sensors enabled the utility company to 1) avoid for their customer to shut down their operations while conducting their investigation, 2) quickly identify the source of the equipment malfunction, 3) improve their customer relationship.
Having read about the above examples, what do you think your company can do to better troubleshoot power quality issues? I’d love to hear your thoughts in the comments section below.