Electric Power Research Institute Incorporated

Narain G Hingorani

Mario Rabinowitz

E Robert Perry

Harshad Mehta

A transmission line power flow control system and method selectively reverses power flow direction and controls power flow level over a transmission line. A capacitor having a variable capacitive impedance is selectively inserted in series with the line. The capacitor has a maximum capacitive impedance magnitude which exceeds the magnitude of the inductive impedance of the transmission line. A switching device in parallel with the capacitor inserts and removes the capacitor from the line. The capacitor maybe inserted and removed in a stepwise fashion using several modules, or in a gradual fashion by using inductors in series with the modular switching devices. In response to measurements of power flow parameters, such as line current and line to ground voltages, a controller controls the switching device(s) to selectively vary the net impedance of the transmission line to control the direction and magnitude of power flow therethrough.

Transmission line power flow controller

An advanced solar cell having an improved efficiency over known conventional solar cells uses an external electric field to enhance the conversion of solar energy into electrical energy. The advanced solar cell has a layered extrinsic semiconductor with a lightly doped base layer sandwiched between two oppositely and heavily doped layers to form a P-N junction within the semiconductor. The base layer has opposing incident and collection surfaces, at least one of which has recessed contact regions interspersed between biasing regions. At least one of the heavily doped layers is substantially confined within the recessed contact regions. Overlaying the biasing region is an enhancement layer, such as a layered MOS structure. Biasing the enhancement layer provides an externally generated electric field to the semiconductor which enhances a depletion region formed around the P-N junction when photon radiation impinges on the semiconductor. A transparent layer of a conductive material may overlay one of the heavily doped layers or comprise a portion of the MOS structure. A method is also provided of converting solar energy into electrical energy.

Advanced solar cell

Apparatus for washing the disc portions of an electrical insulator includes first and second mating housing portions for positioning about the discs and fluid lines for delivering a cleansing fluid through the housing portions for cleaning the surface of the discs. The two mating housing portions preferably define a basin for collecting the cleansing fluid and facilitating removal of the cleansing fluid after use. A support assembly including a robotic arm positions the first and second mating housing portions about the discs of the electrical insulator for cleaning. A cleaning liquid such as water or freon or a cleaning gas such as air or steam is applied through the mating housing portions for cleaning the surface of the discs. Following the cleaning, a surface-enhancing material such as a silicone coating can be applied to the surface of the insulator for protection from future contamination and make the insulator more resistant to electrical or mechanical degradation.

Apparatus for washing electrical insulators

A technique is disclosed herein for separating out one group of polar particles for example PCB molecules having polar moments of given magnitudes, from a separate group of polar particles, for example oil molecules having polar moments of lesser magnitude, in a mixture of the two. This is accomplished by utilizing a chamber containing a substance which has an affinity for the first particle, preferably neoprene in the case of PCB. The substance is carried by arrangements of electrodes or the like which produce a non-uniform electric field in the chamber which causes the first particle, e.g. the PCB, to be attracted toward the substance carried by the electrodes, e.g., the neoprene, faster than the second particles. In this way, first particles are separated out from the mixture and are absorbed by a particle collecting substance of suitable type.

Removal of PCB from oil and other liquids

Subsynchronous oscillations and DC offset in an electrical power system are dampened by measuring the half-cycle period of current or voltage line waves, comparing the measured half-cycle time periods to a desired half-cycle time period and dissipating the line waves in measured half-cycle time periods which are longer than the desired half-cycle time period. Damping apparatus includes a reactance connected in a power line with selectively bidirectional conductors in parallel with the reactance whereby the reactance can be shorted. Alternatively, the selectively bi-directional conductors can connect a power line to ground or neutral when half-cycle time periods exceed a desired half-cycle time period.

Method and means for damping subsynchronous oscillations and DC offset

Reactance means serially connected in a power line is shunted by selectively bidirectional conduction means which is triggered in response to half-cycle time periods of current waves exceeding a desired half-cycle time period and also in response to an over voltage across the reactance means.

Means for damping subsynchronous oscillations in an AC power system

Spurious subsynchronous and supersynchronous electrical signals in an electrical power system are detected rapidly and reliably by generating an electrical signal which is proportional to the power signal and rectifying the generated signal. The rectified signal includes a dc component and a component having a frequency equal to the difference of the contact power frequency and the spurious signal frequency. The component is readily identified by a tuned filter and detector whereby remedial action can be taken to eliminate the spurious signal.

Method and means for detecting spurious electrical signals in an

Subsynchronous oscillations and DC offset in an electrical power system are dampened by measuring the half-cycle period of current or voltage line waves, comparing the measured half-cycle time periods to a desired half-cycle time period and dissipating the line waves in measured half-cycle time periods which are longer than the desired half-cycle time period. Damping apparatus includes a reactance connected in a power line with selectively bi-directional conductors in parallel with the reactance whereby the reactance can be shorted. Alternatively, the selectively bi-directional conductors can connect a power line to ground or neutral when half-cycle time periods exceed a desired half-cycle time period.

A sealed environment such as in a gas insulated electrical substation is cleaned by introducing a cleansing fluid in vapor form into the environment and condensing the vapor on surfaces within the environment. The condensed fluid is then removed and filtered to extract contaminants such as particulate matter. The cleansing fluid can be continuously introduced or periodically introduced during the cleaning process. By selecting a cleansing fluid with electrical insulating properties and a vaporization temperature lower than the condensation temperature of the gas insulation, electrical apparatus can be cleaned during normal operation of the apparatus.

Method and means for cleaning the gas insulated environment of an

Circuitry for limiting the instantaneous peak current, under fault conditions, of an AC power line, includes a high speed circuit breaker in series with a first capacitor in a main current-carrying branch, which branch is paralleled by two additional branches. According to various embodiments these branches contain various combinations of resistance, capacitance and spark gap elements whereby upon occurrence of the excess fault condition, the high speed circuit breaker opens. Thereafter the voltage buildup across the first series capacitor is sequentially commutated to a second branch having a capacitor and spark gap, with a predetermined arc-over voltage, and subsequently to a third resistive branch. The third branch effectively provides the peak current limiting impedance.

Growing community of inventors

Los Altos Hills, CA, United States of America

Narain G Hingorani