NxtPhase Optical I, V Transducers for High Voltage

NxtPhase Optical I, V Transducers for High Voltage

NxtPhase Corp., Vancouver BC, has developed a family of optical sensors to measure current, voltage, and power in high voltage power systems. These devices appear to be on the verge of becoming a commercial reality, and offer high accuracy, bandwidth and dynamic range. Integrated into the all-digital electronic substation measurement and control system of the future, they will help revolutionize metering, protection, and power quality management.

These optical voltage and current sensing technologies came out of two parallel independent development programs – one in the US and the other in Canada.

Current Sensor–
Honeywell applied fiber-optic gyro technology developed for demanding civil and military navigation applications to the measurement of current, and teamed with Texas A&M to produce a sensor. The first deployment was with Arizona Public Service at the Cholla Generating Station in 1997 where accuracy of 0.03 per cent has been demonstrated. Honeywell entered into a partnership NxtPhase, who has a complementary voltage technology and a similar market vision.

Voltage Sensor–
The other half of the NxtPhase story begins with Carmanah Engineering Ltd. – a successful hi-tech spin-off from the University of British Columbia (UBC). Carmanah, UBC and BC Hydro partnered to develop an integrated optic voltage sensing technology based on a unique electric field sensor called the Integrated Optic Pockels Cell (IOPC). Significant technological breakthroughs led to an extremely accurate optical voltage transducer that avoids the environmental concerns of alternative optical or conventional technologies. The first IOPC sensor was successfully deployed in 1997 at the Ingledow substation of BC Hydro.

Optical Voltage and Current Transducer–
The NXVCT combines both the optical voltage and current transducers in one instrument, over the range of transmission voltages from 69 kV to 765 kV.

Applications include:
– Accurate metering of independent power plants (The dynamic range means accuracy at 1 amp and at 100,000 amps. This can have substantial revenue implications, with the ability to measure power inflow when a plant is not producing power);
– High bandwidth monitoring of power plants, i.e. transients and harmonics; and
– High voltage power quality measurements, to diagnose equipment failures.

Very shortly a technology alliance with BC Hydro will be announced. BC Hydro will conduct field trials to test and demonstrate the devices at one of its high voltage substations to verify performance over time, and at various operating temperatures. The company is looking for customers, partners and investors. They are already in discussions with several UFTO companies and others.

For more information about the company and its products, the website is:

Richard MacKellar, CEO, NxtPhase Corp., Vancouver BC
604-215-9822 x 222, rmackellar@nxtphase.com

Steve Dolling, Director, Marketing
604-215-9822 x233, sdolling@nxtphase.com

Further details on the technology are available:

“Design Options Using Optical Current and Voltage Transducers
in a High Voltage Substation”
IEEE PES Substation Committee Annual Meeting May 1, 2000
Powerpoint presentation gives a good overview.


Here is the first page of each of two articles, and links for the pdf downloads.

“Optical Voltage Transducers for High-Voltage Applications”

Optical methods for the measurement of current and voltage in high-voltage (HV) environments have been attracting more and more attention in the recent years. This is mostly due to the advantages that they offer over conventional instrument transformers. They provide immunity to electromagnetic interference, are typically non-intrusive, provide excellent galvanic isolation, are much lighter and, therefore, easier to transport and install. Early work on optical current and voltage sensing in the HV environment started in the 1970’s [1-5] leading to more practical and accurate systems developed in the 1980’s and 1990’s [6-13]. Also, at the commercial level, current sensing technology (both for technical and economical reasons) led voltage sensing technology. In this paper, we present results obtained using NxtPhase’s optical voltage transducer, NXVT.

Most practical optical voltage sensors use electric field sensors that operate using the linear electro-optic (or Pockels) effect. It should be noted that the sensors themselves are, strictly speaking, electric field sensors and not voltage sensors. However, various means of getting a one-to-one relationship between the voltage applied and the electric field sensed are used to derive voltage. For example the entire voltage can be applied across the electro-optic crystal, or a capacitive divider can be used to apply a well-known fraction of the voltage to be measured across an optical electric field sensors. There are advantages and disadvantages to each of these methods. Nevertheless, most successful devices in the past have used optical fibers for the transmission of light, bulk electric field sensors as sensing elements, and SF6 gas for insulation.

The NXVT introduced here combines the typical benefits of optical sensing technology with some additional features that provide further benefits to the user. For example, it does not use SF6 or oil-paper insulation, making it more environmentally friendly and much safer to use. The NXVT uses multiple miniature electric field sensors inside a high-quality post insulator, in a proprietary manner, to measure voltage with high accuracy.


“Optical Current Transducers for High Voltage Applications”

Over the past 15 years, optical current sensors have received significant attention by a number of research groups around the world as next generation high voltage measurement devices, with a view to replacing iron-core current transformers in the electric power industry. Optical current sensors bring the significant advantages that they are non-conductive and lightweight, which can allow for much simpler insulation and mounting designs. In addition, optical sensors do not exhibit hysteresis and provide a much larger dynamic range and frequency response than iron-core CTs.

A common theme of many of the optical current sensors is that they work on the principle of the Faraday effect. Current flowing in a conductor induces a magnetic field, which, through the Faraday effect, rotates the plane of polarization of the light traveling in a sensing path encircling the conductor. Ampere’s law guarantees that if the light is uniformly sensitive to magnetic field all along the sensing path, and the sensing path defines a closed loop, then the accumulated rotation of the plane of polarization of the light is directly proportional to the current flowing in the enclosed wire. The sensor is insensitive to all externally generated magnetic fields such as those created by currents flowing in nearby wires. A measurement of the polarization state rotation thus yields a measurement of the desired current.

The optical current transducer being developed by NxtPhase (the NXCT) is an offshoot from the Honeywell fiber optic gyro program. Honeywell has been producing fiber optic gyros for a variety of commercial aviation applications since 1992. Extensive life and reliability testing has been carried out on the product to meet the stringent flight qualification criteria. Early on, Honeywell realized that this technology, with only minor modifications, could be applied to the field of current sensing, and a program to diversify into this area was maintained by Honeywell for several years. In late 1999, Honeywell joined with Carmanah Engineering to launch NxtPhase with the charter of commercializing the technology.

Principle of Operation
The NXCT uses the Faraday effect, but in a different architecture than the more well known polarimetric technique. The NXCT is a fiber optic current sensor and it works on the principle that the magnetic field, rather than rotating a linearly polarized light wave, changes the velocities of circularly polarized light waves within a sensing fiber wound around the current carrying conductor [1]. The effect is the same Faraday effect but differently formulated. We have found in our experience and heritage from the Honeywell fiber-optic gyroscope program that, for a variety of reasons, it is easier to accurately measure changes in light velocity than changes in polarization state. Chief among these reasons is that by using a velocity measurement scheme, we do not need to construct the sensing region from annealed fiber which is brittle and difficult to work with in a production environment.

Zero Emission Coal (Los Alamos)

(One of a series of UFTO Notes based on the recent visit to Los Alamos National Laboratory)

Zero Emission Coal

Los Alamos is working to eliminate the environmental concerns associated with the use of fossil fuel, which will continue to be an important energy source well into this century. One technology the Laboratory is developing to achieve this goal is a zero emission process for converting coal and water into hydrogen, which is then converted into electricity, with virtually no emissions of pollutants. Thirteen entities with interests in coal production and energy generation have teamed up to form the Zero Emission Coal Alliance (ZECA) which plans to commercialize this process within five years.

The Technology In the context of DOE’s “Vision 21” goal to eliminate environmental concerns from the use of coal. Los Alamos is developing technology to achieve a zero emission process for converting a coal and water slurry into hydrogen, which is in turn converted to electricity via a high-temperature solid-oxide fuel cell.

The new process builds on CONSOL’s CO2 Acceptor Process, which was piloted in the 1970’s. While still relying on cycling of calcium oxide (CaO) to drive the production of hydrogen, enhancements produce separate streams of hydrogen and CO2. The hydrogen is used to generate emission-free electricity and the CO2 is reacted with abundant magnesium silicates to be permanently sequestered as a solid, inert and stable mineral carbonate.

Hydrogen gas is produced from water and coal using a calcium oxide (CaO) to calcium carbonate (CaCO3) intermediary reaction. Through a subsequent reaction, the calcium carbonate generated by hydrogen production is converted back into calcium oxide and a pressurized stream of pure CO2. The calcium oxide is recycled to drive further hydrogen production, and the CO2 stream is ready for easy disposal.

The hydrogen is fed to solid-oxide fuel cells to generate electric power, and the ~50% of waste heat produced by the fuel cells is not truly wasted because it is reinjected into the process to drive the calcination reaction.

The already pressurized CO2 stream is reacted with magnesium or calcium silicate mineral deposits to form geologically stable mineral carbonates. (The reaction is part of the natural geological carbon cycle; therefore, all mineral end products are naturally occurring and completely benign.) The mineral sequestration process is economically viable because the CO2 stream is non-mechanically pressurized in the hydrogen production process and the carbonation reaction is exothermic (i.e., it creates energy instead of consuming it).

In addition, the types of mineral deposits needed to carry out the reaction are abundant enough to handle all the carbon associated with the world’s coal reserves. Magnesium-rich ultramafic rocks, primarily peridotites and serpentinites, are the main candidates for mineral carbonation. Deposits distributed throughout the world, though in specific concentrated areas on each continent.

The Alliance
Thirteen entities from the United States and Canada with interests in coal production and the use of coal for electrical generation have agreed to contribute $50,000 each to form ZECA.

Phase I: ZECA is currently structured with an executive team headed by Jim Berson, Director of Planning and Business Development from Kennecott Energy/Rio Tinto, a technology team headed by Dr. Hans Ziock, senior scientist at Los Alamos National Laboratory, and a business team headed by Alan Johnson, President of The Coal Association of Canada. The goal of Phase I is to develop a business plan and a technical plan leading to the completion of a pilot plant in a five year time frame.

ZECA has begun to proceed with Phase I. The alliance however still welcomes the participation of additional members to ensure a broad spectrum of industry participation and expertise. As alliance members, participants in Phase I have the opportunity to help guide the work conducted under the supervision of the technical and business committees, as well as the opportunity to serve or participate on those committees at their discretion.

Additional information is available online:

for technical information:
Klaus Lackner, 505-667-5694, ksl@lanl.gov
Hans Ziock, 505-667-7265, ziock@lanl.gov

for business information:
Jim Berson, 307-687-6049, bersonj@kenergy.com
Alan Johnson, 403-262-1544, johnson@coal.ca

(I have several technical papers from Los Alamos, which I can send on request.)

ELISIMS: Detailed Simulation of Power Industry (Los Alamos)

(One of a series of UFTO Notes based on the recent visit to Los Alamos National Laboratory)


“A Comprehensive, Detailed Simulation of the Electric-Power Industry: Harnessing the Los Alamos National Laboratory High-Perfomance Computing Infrastructure,”

Los Alamos is proposing to use their supercomputing capabilities to address policy analysis of utility restructuring by modeling the entire power system at an unprecedented level of detail — and breadth. Building on experience in transportation modeling**, they suggest that computer simulation at a sufficient level of detail calls for very high-performance computing: (from the abstract of a paper LA-UR-98-5920 )

——- “The electric-power infrastructure is a complex system consisting of hundreds of thousands of independent agents coupled by a dynamically constrained transmission system. Actions of the independent agents are governed by both economic objectives and constraints imposed by federal, state, and local policies. Purchasing decisions by millions of independent consumers constrained jointly by market policies and transmission-system realities will lead to unexpected emergent system behavior with potential consequences on reliability and quality.

Prior testing of energy policy is required, and this requires computer simulation. To do this at a sufficient level of detail calls for high-performance computing and the analysis and validation of emergent behavior.” ——-

The plan is ambitious: (from LA-UR-98-4952)

—— “In a nutshell, we propose to develop and deploy a comprehensive, detailed simulation of the electric industry:

– Comprehensive in that we will include the whole North American continent because that natural limit is becoming the scale of tight interconnection.

– Detailed in that we will include each significant element at the level of generators, transmission elements, varied control elements, and load distribution buses.

– Industry in that we will include the regulatory, financial, and market entities that interact with the engineering elements.

We will design a linked multi-resolution simulation hierarchy with which users may instantiate as much detail and as great a (geographic) scope as required for their particular analyses. Stability studies may require complete calculations in both scope and detail. Other studies (made cheaper by employing either the mixed resolution or a reduced scale) will be more secure with the ability to validate against the full calculations.” ——–

The goal is to capture both power flow and market dynamics together, in a way that hasn’t been accomplished before. A pilot project is underway with the California ISO to evaluate future scenarios for the structure of RTOs in the west.

A 33 page summary report (March 2000) (LA-UR-00-1572) was recently completed, which is available in pdf format:
It provides a more complete write-up of the original applications’ study and a cross-mapping to the recommendations of the DOE’s POST report (section 1.5 and Table 1 on page 11).

The program has a webpage at:

Dale Henderson, 505-665-2151, dbh@lanl.gov
Jonathan Dowell, 505-665-9193, ljdowell@lanl.gov

**The TRansportation ANalysis SIMulation System (TRANSIMS)