1.1- Power Quality & Power Problem Definitions
There are numerous types of power quality issues and power problems each of which might have varying and diverse causes.
To further compound the matter, it is all too common that different power quality problems can occur simultaneously, interchangeably or randomly.
The following is a brief summary of typical power problems:
Frequency, Harmonics, Interruption (Blackout), Noise, Notching, Over voltage, Sag (Dip), Short Circuit, Surge Swell, Transient (Surge) and under voltage (Brownout)
Fault ( In Electric Power )
In an electric power system, a fault is any abnormal flow of electric current. For example, a short circuit is a fault in which current flow bypasses the normal load. An open-circuit fault occurs if a circuit is interrupted by some failure. In three-phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a "ground fault" or "earth fault", current flows into the earth. The prospective short circuit current of a fault can be calculated for power systems. In power systems, protective devices detect fault conditions and operate circuit breakers and other devices to limit the loss of service due to a failure.
Interconnections of components forming system configurations which will provide a desired system response as time progresses.
Open- and closed-loop control
The basis for analysis of a control system is the foundation provided by linear system theory, which assumes a cause-effect relationship for the components of a system.
A component or process to be controlled can be represented by a block. Each block possesses an input (cause) and output (effect).
The input-output relation represents the cause-and-effect relationship of the process, which in turn represents a processing of the input signal to provide an output signal variable, often with power amplification. An open-loop control system utilizes a controller or control actuator in order to obtain the desired response (Fig. 1).