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The 2015 NERC State of Reliability Report states that 31% of mis-operations are attributed to incorrect settings/logic/design errors [1]. According to the report, one major cause of mis-operations is human error. We know today that the current relay settings development process is laborious and difficult to complete in an accurate manner with today's tools. This process requires the setting engineer...
Since differential relays offer solutions for multiple applications, one can conclude that the relay engineer must deeply understand not only the element behavior, but also how each relay calculates its protection functions for the given application. This paper has described the behavior of a reactor energization and the response of two different differential relays. In addition, this paper has provided...
As discussed throughout this paper, the employment of load encroachment and OOS blinders make it difficult to ensure that the relay will operate for symmetrical faults when these two functions are enabled and still comply with the standard. The use of current differential relays solves this issue when these type of relays are available. The relay engineer can also decide to disable the OOS function...
The potential of using synthetic herbivore-induced plant volatiles (HIPV) (e.g., methyl salicylate, MeSA) as a cultural tool to enhance conservation biological control of mites is being researched in commercially grown hops in Washington State, USA. Compared to unbaited blocks, hop yards baited with controlled release sachet (CRS) dispensers of synthetic MeSA recruited larger (3-5×) populations of...
This paper has shown the benefits of viewing and determining neutrals shift by graphically showing it in the voltage triangle along with the phasor diagram. We have demonstrated how neutral shifts are observed on solid grounded, ungrounded and semi-ungrounded systems. Finally, it was determined that neutral shifts can have a direct impact on the fault phase voltage and therefore affecting protective...
These new test methods are a new tool that can be used to verify the stability of differential relays for external faults. By simulating real time events, one can discovered errors that were not possible using single phase test methods. As a result, it is encouraged that new microprocessor relays be tested as close to real system events as possible.
Flashover operations due to a change in the physical positioning of a foreign object with an energized conductor are a common occurrence seen throughout many transmission and distribution systems. The inception of a fault from a flashover between two stationary conductors, however, is not as prevalent. This is primarily due to extensive protection system coordination and insulation design specifications...
Typically, distance relays protect transmission lines from power system faults by using the method of step distance protection. This method uses the line impedance as the basis to form zones of protection and each zone is calculated by a predetermined percentage of the line impendence. The impedance setting will establish the relay's impedance characteristic, which is graphically displayed as circles...
Proper interpretation of fault and disturbance data is critical for the reliability and continuous operation of the power system. A correct interpretation gives you valuable insight into the conditions and performance of various power system protective equipment. Analyzing records is not an intuitive process and requires system protection knowledge and experience. Having an understanding of the fundamental...
Over the years, different methods have been used in order to avoid problems with load encroachment, and each method presents its own set of advantages and disadvantages. Regardless of the method used, each relay will have a maximum "loadability limit" that will cause the relay to operate under high load conditions. Therefore, it is important for the relay engineer to understand and take...
Modern microprocessor-based low-impedance differential relays use a percentage differential principle that utilizes traditional dual slope characteristics. Many differential mis-operations occur with these traditional methods as a result of CT saturation, DC offset, or current subsidence. One reason is because the traditional operating and restraining principles rely heavily on the current magnitude,...
Power transformers are traditionally protected by differential protection schemes that use voltages and currents to detect abnormalities in the differential zone of protection. For this type of scheme, a short circuit or high magnitude current must be present to initiate a trip. However, this scheme might not be ideal when transformers need to be overloaded to mitigate contingency conditions. Using...
With the increased use of renewable wind energy, wind farms are being built in remote areas, often far from load centers. The required long transmission lines are often constructed with series capacitive compensation to electrically shorten the lines. Events in the transmission system can cause interactions between the series capacitors and the system's inherent impedance which can result in sub-synchronous...
Power transformers are traditionally protected by differential protection schemes that use voltages and currents to detect abnormalities in the differential zone of protection. For this type of scheme, a short circuit or high magnitude current must be present to initiate a trip. However, this scheme might not be ideal when transformers need to be overloaded to mitigate contingency conditions. Using...
Proper interpretation of fault and disturbance data is critical for the reliability and continuous operation of the power system. A correct interpretation gives you valuable insight into the conditions and performance of various power system protective equipment. Analyzing records is not an intuitive process and requires system protection knowledge and experience. Having an understanding of the fundamental...
This work assessed the effect of an enriched culture medium and synthetic seawater on the growth and production of exopolymeric substances (EPS) of a Desulfovibrio sp. strain, isolated from a Mexican oil well. The EPS (mainly consisting of proteins) growth was only achieved after exposing sulfate-reducing bacteria to culture media under dissimilative conditions that predominantly promoted the growth...
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