Safer by Design
by Tim Figura
Recently, I attended a conference where a manufacturer of electro-mechanical distribution voltage regulators for medium-voltage lines was giving an in-depth presentation on their products. I was surprised to see how many slides focused on operating and troubleshooting the equipment safely. They documented the various ways that it can fail and showed pictures to highlight what can happen if a step is skipped in the process of taking the unit out of service.
As most utility engineers and line crews know, a regulator must be put into the neutral position before it can be bypassed. Without this step, bypassing a regulator is equivalent to shorting turns on the transformer windings, and the outcome can lead to catastrophic equipment failure and risk to line-crew safety. The manufacturer recommends that at least three different methods be utilized to determine that the regulator is actually in neutral. If this is not possible, the distribution line must be de-energized to protect the safety of the workers, causing a power outage to the nearby customers.
A result of the need for these safety procedures is that conventional voltage regulators, independent of manufacturer, are considered to be one of the most dangerous pieces of equipment that line workers deal with regularly.
Gridco Systems In-line Power Regulators™ (IPRs) utilize power electronics, rather than a traditional magnetic core, to buck (lower)/boost (raise) voltage continuously by up to 10% on the low-voltage side of distribution service transformers in overhead or underground networks. The units are designed for a 25-year life with no maintenance. Thanks to passive cooling, there is no oil or other liquids that line workers need to be concerned with or that can result in any type of environmental spill.
The IPR does not utilize tap positions on a transformer to regulate voltage and therefore cannot “get stuck” mistakenly boosting or bucking and causing adverse voltage conditions. Because voltage regulation is accomplished by injecting a continuous voltage from a power electronics inverter, there is no magnetic structure that needs to be “neutralized” before bypassing.
In fact, the IPR has, by design, a fail-safe bypass mechanism built-in, that automatically removes the inverter-based voltage regulation capabilities from the circuit, if necessary
or can be manually initiated, if desired. Therefore, if the power electronics were to ever fail, the customers downstream would still receive power, just without voltage regulation. As a result of this internal bypass mechanism, the power electronics module is even field-replaceable without a required outage.
With IPRs, alarms are automatically sent to either a SCADA/DMS/VVO system or the Gridco GMAP-hosted system. If the unit has transitioned into the bypass state, technicians in the utility operations control center will be aware and can take appropriate action, potentially diagnosing and resolving the issue remotely without a truck roll.
The power electronics-based IPR represents a departure from traditional approaches to voltage regulation with benefits of speed, precision and fail-safe operation that truly put it in a different class of equipment, as compared to its electro-mechanical distant cousins with their inherent failure risks and complex service procedures.
Visit http://www.gridcosystems.com to learn more about how Gridco Systems products can help your utility get the maximum benefit from your VVO/CVR programs, provide flexibility for DER hosting or improve the overall voltage and power quality for your customers.