Malfunction detector for static VAR controllers

DETAILED DESCRIPTION In general the invention relates to a static VAR generator for providing reactive compensation to an electrical system incorporating a malfunction detector.
The operating circuit for the SVG can be thought of as two interrelated sections--the control section for providing a linearized current control signal, the output section for using this linearized control signal to produce reactive compensation for the electrical network.
The control section comprises a primary current demand computer (CDC) that in general includes an error generator, slope control and an integrating amplifier.
The output section is a linearized output circuit including a firing angle controller, thyristor gating and power circuits and thyristor switched reactive components such as and/or capacitors.
A transducer monitors the controlled variable, typically the output signal of the SVG and produces a feedback signal.
The primary CDC utilizes the feedback signal as well as a reference signal generated by an adjustable reference signal source for producing a first linearized control signal in response to the difference between the reference signal and the feedback signal.
The linearized control signal also incorporates the desired V-I slope characteristic.
The malfunction detector comprises a tracker CDC, two comparators and an equalizer circuit.
The tracker CDC, substantially idential to the primary CDC, provides a second linearized control signal in response to the reference signal and the feedback signal.
The second linearized control signal is compensated by the equalizer circuit by an amount that counters the effect produced in the second linearized control signal by the offset and component tolerances of both the primary CDC and the tracker CDC; thereby, making the second linearized control signal equal to and track the first linearized control signal.
The first comparator compares the compensated second linearized control signal with the first linearized control signal.
A first fault output is produced whenever these two linearized control signals are not substantially equal to one another