P.K. Sen

• PhD
• Professor at Colorado School of Mines

The legacy electric grid is changing at a fast pace and is expected to have high penetration levels of distributed energy resources (DER) and non-linear loads at the distribution level. This introduces several challenges to the monitoring and control of the distribution network. One challenge is to address the significant increase of higher-order h...

Common practice in transmission and distribution (T&D) systems analysis has been to treat them independently by decoupling those at the point of common coupling (PCC). With the large amount of distributed energy resources (DER) being added in distribution networks, the interactions between T&D systems at PCC produce unacceptable errors. This study...

This paper primarily deals with the design of an Information and Control Technology (ICT) network for an advanced metering infrastructure (AMI) on the IEEE 34 node radial distribution network. The application is comprised of 330 smart meters deployed in the low voltage system and 33 data concentrators in the medium voltage system. A power line carr...

In off-grid wind power plants, the uncertainty of net load becomes the main factor that controls the operation and planning of these plants. The term net load refers to system demand minus the generation from variable renewable resources. Energy storage system is a key solution for system operators to provide the required flexibility needed to bala...

Cybersecurity is a topic of increasing importance and interest to small utility operators like rural electric associations. Cyberattacks are a threat to our society's functioning, and cybersecurity is an urgent need in areas that include national security, business operations, and regulatory compliance. Several fundamental concepts can guide an ope...

Integration of large-scale utility-owned distributed generation (DG) units can be a vital technique in relieving transmission line congestion and improving the reliability of the power grid. However, the impact of DG installation on line congestion management is significant at locations where transmission lines are most heavily loaded. This study p...

Environmental issues and greenhouse gas emissions, concerns of generating electricity by burning fossil fuel, and recent increase in energy price, the number of Plug-in Electric Vehicles (PEVs) has been rising in recent years and will continue to grow. Modern electric power system at the same time is gradually evolving into a smarter grid with two-...

Self-Excited Induction Generators (SEIG) have recently emerged for wind energy conversion in remote and rural areas due to many advantages as standalone induction generator over Grid Connected Induction Generators. However, poor voltage and frequency regulation under varying load and speed is the prime disadvantage of standalone SEIG. Steady state...

The North American electric power grid is the largest and among most complex systems in the world. The National Academy of Engineering (NAE) has gone so far as to call it the 'supreme engineering achievement of the 20th century.' It is now aging and faces significant challenges moving into the 21st century. Of particular concern is the growth of 'S...

Overall electric energy conservation and improvement in electrical energy efficiency has been a topic of interest to the electric power industry for long time, since 40% of total primary energy used is in the form of electricity. There are many facets to the energy conservation and/or energy efficiency techniques. Energy conservation by voltage red...

Climate change concerns mandated renewable portfolio standards, lucrative government incentives, and accelerated cost reduction in renewables, and distributed energy applications are driving steep growth in system installations. Distributed energy resources (DERs) are not commonly connected to a bulk power transmission system but are interconnected...

IEEE Std. 80 “IEEE Guide for Safety in AC Substation Grounding” is most commonly used in the design of substation ground grids and is the basis for today's commercially available software. This paper discusses an alternate design approach for substation grounding in areas that have high soil resistivity. It discusses various methods for designing a...

Selecting proper transformer winding connections along with the neutral grounding has played an important role in the design and applications of power system protection scheme at all levels for many decades. This paper addresses how a transformer connection and the grounding currently utilized in various distributed generation projects can have a c...

Almost 56% of the total primary energy used (about 100 Quads in 2010) in USA is wasted. 40% of the total energy is used to generate electricity with an overall efficiency of about 32% (or 1/3rd). The transportation sector uses about 27% (1/4th) with an overall efficiency of 25%. The industrial/ commercial sector uses 47% with an overall efficiency...

In conventional and harmonic power flow analysis, three-phase induction motors are typically modeled using constant parameters (power or impedance). Such models do not fully capture the impact of voltage deviation, unbalance, and harmonics on motor losses. This paper discusses simple frequency-domain induction motor modeling techniques suitable for...

The induction motor equivalent circuit parameters are required for many performance and planning studies involving induction motors. These parameters are typically calculated from standardized motor performance tests, such as the no load, full load, and locked rotor tests. However, standardized test data is not typically available to the end user....

This paper investigates and compares the implementation of two FACTS (Flexible AC Transmission System) devices to overcome the voltage stability issue for Doubly Fed Induction Generator (DFIG)-based wind farm. The study includes the implementation of both a static synchronous compensator (STATCOM), and the static var compensator (SVC) as dynamic re...

Interest in photovoltaic systems, both large and small scale applications, has been growing since the renewable portfolio standard in the US was enacted as Law. This paper provides state-of-the-art information on photovoltaic energy applications, various types of PV collector systems, and how to size the stand-alone PV system in a hybrid design. In...

The root-cause of the workforce demographics gap related to electric power and energy industry in tracked back in the early 50's. The problem got amplified due to the lack of foresight by the industry, electric utility deregulation and restructuring efforts. The impact cascaded into the talent supply pipeline and university power engineering progra...

The integration of Doubly Fed Induction Generator (DFIG) based wind farm into the power grid has become a major concern for power system engineers today. Voltage stability is a key factor to maintain DFIG-based wind farm in service during the grid disturbances. This paper investigates the implementation of STATCOM to overcome the voltage stability...

The petroleum and chemical industries use nearly 26% (≈ 1/4 th ) of all electricity consumed by industry and nearly 7% of all electrical energy consumed in the US. A segment of the overall energy industry using such a large percentage of the electricity can hardly help but be affected by the future trends in the usage and generation of electricity....

With increased penetration of wind power into the electrical grid, Doubly Fed Induction Generator (DFIG) for wind turbines are largely deployed due to their variable speed feature and hence influencing system dynamics. This paper presents the modeling and control of DFIG in details, where the stator is connected directly to a stiff grid and the rot...

For many engineering studies involving commercial buildings, quick but reliable estimates for building electrical load characteristics are helpful. Often, little information about the building electrical characteristics is known, so such estimates must be drawn from general engineering knowledge or historical data. In the United States, the Commerc...

In order to promote power and energy engineering education and career opportunities and to meet the future needs and expectations of the power and energy industry in the 21^st century, the curriculum and course contents must be very carefully designed and delivered. Preparing future generation of electric power and energy systems engineer...

Long-term solutions of global energy crisis and applications of mass scale renewable energy depend heavily on the availability of storage system. Currently the storage technology for large scale power system is practically non-existent except for the pumped hydro scheme, which has been known and successfully implemented for over 80 years. Besides b...

Wind power generation is becoming increasingly common in the portfolio mix of many utilities around the world. Wind turbines are presently available up to 5MW. Smaller turbines may be installed for individual customers and connected to the grid at the distribution level, and larger units are typically combined in a wind “farms” connected to bulk po...

The compact florescent lamp (CFL) is becoming an increasingly popular light source for households replacing the commonly used incandescent lamps. CFLs have advantages and disadvantages; among those advantages are cost savings, energy reduction, increased efficacy, and longer life expectancy. Appearance, poor power factor and harmonic impact on dist...

Corrosive sulfur in transformer oil has been identified to cause sudden and unexpected failures of several transformers in recent years. It has been decades since corrosive sulfur has caused such problems. This paper discusses the problems caused by corrosive sulfur, why the problem has resurfaced, new test methods developed to detect corrosive sul...

There are many industrial applications of large-scale dc power systems, but only a limited amount of scientific literature addresses the modeling of dc arcs. Since the early dc-arc research focused on the arc as an illuminant, most of the early data was obtained from low-current dc systems. More recent publications provide a better understanding of...

With the increasing use of distributed energy (DE) systems in industry and its technological advancement, it is becoming more important to understand the integration of these systems with the electric power systems. New markets and benefits for DE applications include the ability to provide ancillary services, improve energy efficiency, enhance pow...

Successful operation of electric grid requires continuous real-time balancing of supply and demand including losses. The US grid operates effectively without much storage at present. However, the peak demand and generation facilities are growing at a faster rate in comparison to the transmission facilities. The system has observed some congestion p...

This paper, prepared by the Climate Change Technology Subcommittee, a subcommittee of the Power and Energy Society Energy Development and Power Generation Committee, identifies key technical issues facing the electric power industry, related to global climate change. The technical challenges arise from: 1) impacts on system operating strategies, co...

There is an increasing demand both by legislation and the public for a more secured, reliable and efficient power system using dispatchable and non-dispatchable renewable resources. However, the existing design and operational practice of the electrical power grid does not lend itself easily to the incorporation of non-dispatchable renewable energy...

Climate change concerns, mandatory requirements for the renewable portfolio standards, incentives offered by the Government, and cost reduction in renewables and distributed energy sources (DER) are some of the driving forces for the steep growth in DER installations. DERs are commonly connected near the load in the electric power distribution syst...

The exposure to hazards associated with electrical arcing phenomena when working on energized equipment is a topic of significant interest to industrial plant personnel. This article provides an overview of the current arc-flash standards, focusing on the methods used to calculate incident energy levels in a system. A thorough sensitivity analysis...

Climate change concerns, mandated renewable portfolio standards, lucrative government incentives, and accelerated cost reduction in renewables and distributed energy applications are driving steep growth in system installations. distributed energy resources (DER) are not commonly connected to a bulk power transmission system, instead are interconne...

Distributed Energy Resources (DER) including renewables of various designs and ratings have become increasingly common in the last decade. Many States and the Federal government have passed Laws mandating a certain amount of energy be generated using renewables and/or alternative fuels that lend themselves to smaller power plants being connected to...

As the overall structure of how electricity is delivered continues to change, ultracapacitor is considered as a possible energy storage device. Its application considerations range from electronics to large scale power systems. Much of its current uses in large scale applications, however, are focused on transportation needs with hybrid and electri...

Despite the growing awareness and increased understanding of the hazards associated with arcing faults, incidents of this type continue to occur and individuals exposed to the hazards may be severely injured or killed as a result. Accurately estimating the available thermal energy is a critical aspect of assessing the severity of the arc flash. Ove...

To minimize the necessary calculations when performing loss studies, utilities often measure load factors, try to determine the loss factor, and use the estimated loss factor to determine system losses. This paper examines the relationship between load and loss factors, and discusses the validity of common methods used to determine losses using loa...

Research needs for the US electric power industry to address global climate change are summarized. The research addresses both mitigation, how the industry contributes to climate change, and adaptation, how the industry itself is affected by climate change.

Preparing the future generation of electric power and energy systems engineers in the current academic environment in USA is a challenging task. In order to maintain the interest levels with the undergraduate students and to promote advanced level power engineering education, career opportunities in electric power and to meet the future industry ne...

Electric Utilities permitting interconnection of generation (small and/or large) on their power systems have long had standards which any entity wishing to interconnect has to meet. Recently the growing importance of distributed generation (mostly less than 10 MVA), especially using renewable sources, has prompted the creation of IEEE Std. 1547 whi...

The exposure to hazards associated with electrical arcing phenomena, while working on energized equipment is a topic of significant interest to industrial plant personnel. This paper provides an overview of the current arc flash standards, focusing on the methods used to calculate incident energy levels in a system. A thorough sensitivity analysis...

Sensors, in general, and overall sensor technology have traditionally had a very limited application in substations engineering. With the advent of the modern communications systems, SCADA systems have the potential of transmitting more data. Enormous potential exists to deliver more real time information and data that may increase the security of...

The development of models used to represent electrical arcs has been the focus of numerous research studies through the years. A variety of models, ranging from the simplistic to the elaborate, have been proposed by the international scientific community for DC, single-phase AC, and three-phase AC system calculations. This paper features volt-amper...

Teaching the first entry-level undergraduate course in electric power systems engineering and/or electrical machines and energy conversion in any electrical engineering curriculum, when opportunity arises, is a very difficult task at best. In order to maintain the interest levels with the students and to promote advanced level power engineering edu...

The US Energy Policy Act of 2005 will impact the applications and R&D efforts for every type of renewable energy source. A part of the bill has the stated purpose of achieving energy self-sufficiency by the year 2025 within the US, Canada, and Mexico. This bill also has provisions for anyone wishing to connect to the existing power grid at the dist...

Much research has been done in recent years to aid in the determination of surge protection requirements for medium voltage (MV) motors rated typically between 500-20,000 HP range, and at 4.16-13.2 kV. In order to determine the actual surge magnitude and the corresponding rise time seen by the motor windings, the sources of surges and the factors a...

Not Available

Much research has been done in recent years to aid in the determination of surge protection requirements for medium voltage (MV) motors rated typically between 500-10,000 HP ranges at 4.16 kV-13.2 kV. This paper summarizes all such activities and provides some application guidelines. In order to determine the actual surge magnitude and the correspo...

The Energy Policy Act of 2005 substantially modifies a number of past energy legislation and adds new legislation. A part of the bill has the stated purpose of achieving energy self-sufficiency by the year 2025. The energy bill provides for certain grants to small rural communities. This allocation funding may also be used to upgrade generation fac...

In an effort to develop increased safety awareness related to the electric power industry, Colorado School of Mines (CSM), electrical specialty students are required to take a one- week intensive electrical safety training course. Though safety training should start with young people, it is also an important part of the education for experienced el...

As the demand for energy, both in the form of electricity and transportation fuel, increase around the world, a renewed focus on converting to a hydrogen economy has emerged. Recent advancements in hydrogen technologies and renewable energy applications show the promise of converting to a hydrogen-based economy should become economically feasible i...

Placing a dollar value on electric service reliability causing the disruption of critical social services and the inconveniences to businesses and individuals is nothing new to the electric power industry. The value the customers place on electric service reliability has been studied by utilities and others. This paper provides an overview and revi...

Recent advancements in hydrogen technologies and renewable energy applications show promise for economical near- to mid-term conversion to a hydrogen-based economy. As the use of hydrogen for the electric utility and transportation sectors of the U.S. economy unfolds, electric power utilities need to understand the potential benefits and impacts. T...

At Colorado School of Mines (CSM) there is a unique opportunity to educate the future electrical engineers about the vital topic of electrical safety. All electrical specialty undergraduate students are required to take a three-week (3-credits) Field Session course during the summer months between their junior and senior years. This paper discusses...

As an integral part of the undergraduate engineering degree program requirements at Colorado School of Mines in Golden, Colorado, all students are required to complete a two-semester long (7 credits) capstone senior design class that is multi-disciplinary in nature. The senior design "team" (consisting of eight students from electrical and mechanic...

Over the past two decades, the electricity market in the US has gone through major scrutiny and changes. Most recently the blackout of 2003, high oil prices (over $60/barrel) and restructuring and deregulation efforts have caused the electric power industry to take afresh look. In addition, energy sustainability has also become a major national con...

An Advanced Electric Power and Energy Systems Laboratory (1 cr.) was offered for the first time at Colorado School of Mines (CSM) during the spring 2005 semester. The pilot course represents an innovative approach to lab instruction. This paper describes the course materials developed to introduce the power flow problem to a group of senior level u...

Estimation of the remaining life of a power transformer in service has been of a big concern to most owners, especially when it is known to have been overloaded either continuously or intermittently over long periods. Therefore, to make economical decisions for such transformer replacement, it is critical to estimate the remaining life expectancy....

This paper is the outcome of a technical assessment of the current deregulation and restructuring efforts within the United States' electric utility industry. Ongoing issues and problems exist. Hence, regional and political debates are delaying the determination of how the restructured industry should operate, thereby putting its viability and reli...

A large number of distribution transformers, currently utilized in low voltage (LV) power systems are of dry-type design. This includes, the IEEE Class II ventilated dry-type design with 3-phase kVA ratings in the approximate range of 500 kVA - 2.5 MVA and primary voltage ratings ranging from 4.16 kV to 34.5 kV and the secondary voltage ratings of...

Estimation of a power transformer's remaining life is of concern to most owners, especially when the transformer is known to have been overloaded either continuously or intermittently over long periods. To make economical decisions regarding replacement, it is critical to know how long a transformer is expected to last. This article discusses the i...

Estimation of a power transformers' remaining life is of concern to most owners, especially when it is known to have been overloaded either continuously or intermittently over long periods. Therefore, to make economical decisions for transformer replacement, it is critical to be able to estimate with reasonable accuracy the transformer remaining li...

The transition from the present fossil fuel based economy to a self-sufficiency clean energy world depends upon distinctive power electronic systems for the implementation of alternative energy grid interface. Fuel cell technology is an attractive means of power generation because it is environmentally clean, uses the vast resource of hydrogen as f...

The multifunction digital relay has greatly expanded the science of protective relaying. The new science of protective relaying has resulted in the following improvements and benefits to the petrochemical industry. The multifunction relays typically have a large array of functions that can be used for electrical equipment protection. The multifunct...

In the 1960s numerous damages were documented on 480 V, 3-phase, 4-wire power systems due to arcing ground faults, To alleviate this problem, the National Electrical Code (NEC) now requires ground fault protection in low voltage switchgear with continuous current ratings above 1,000 A and operating at more than 150 V phase-to-ground on solidly-grou...

A debate has existed in the petroleum and chemical industry for years concerning low-voltage (480-600 V) power systems grounding. Since reliability and continuity of service are very important, some engineers in the past preferred using an ungrounded system. The practicality of such ungrounded systems becomes questionable as the extent of coverage...

With the advent in power electronics, increase in power handling capacity of SCR and other power electronic devices and the use of high speed digital signal processor (DSP), new and better control principles are now utilized for the design of numerous variable frequency drives (VFDs) for large induction motors. One of the latest technologies develo...

Economic considerations of possible overloading the transformer and accepting the reduced life expectancy due to higher hot spot temperature rise must be evaluated carefully against the delay in transformer replacement or addition of a second transformer to increase the capacity. This is a very significant question and quite often asked by the syst...

Many of today's users are interested in the overloading capability of their transformers during emergencies and/or planned overloads. Sometimes this also includes carefully estimated loss of life calculations. This paper will address the overloading of power transformers rated above 20 MVA, but less than 100 MVA, following ANSI guidelines. The focu...

The petro-chemical industry is entering the 21st century with a vast array of protective relaying options ranging from the time proven electromechanical to the high speed digital, multifunction relays. While there is still an “art”, there is much more “science” involved with the design and implementation of protective relaying schemes. This paper p...

There are numerous applications where induction generators offer distinct advantages over conventional synchronous machines, resulting in a simplified design and installation at lower first cost and substantial savings in operations and maintenance expenses. Induction generators, however, have some disadvantages which need to be evaluated before pr...

Based on dividing a coil into a number of equal segments and calculating the equivalent circuit parameters, a method is developed to analyze the internal voltage distribution in a single-layer, air-core reactor. The Electromagnetic Transient Program (EMTP) is used to model the reactor and to solve for internal voltage distributions. Simulation resu...

A debate has existed in the petroleum and chemical industry for years concerning the grounding of LV (480-600 V) power systems. Since reliability and continuity of service are important in the petrochemical industry, some engineers in the past preferred using an ungrounded system. The practicality of such ungrounded systems becomes questionable as...

A debate has existed in the petroleum and chemical industry for years concerning the grounding of LV (480-600 V) power systems. Since reliability and continuity of service are important in the petrochemical industry, some engineers in the past preferred using an ungrounded system. The practicality of such ungrounded systems becomes questionable as...

A power distribution system distributes power from a substation to the point of power utilization. Voltage drops occur naturally on distribution systems. It is designed to keep the voltages near the nominal values, and usually within a few percent limit. Besides load balancing, electric utilities commonly use both voltage regulators and shunt capac...

With the increase of nonlinear loads on utility distribution systems, the voltage and current waveforms are becoming more distorted and the power quality is deteriorating. Since this is becoming a wide spread problem today, and new, more strict, distortion guidelines are under development, utility engineers are having to deal with analyzing and pla...

Based on the National Institute of Standards and Technology statistical data on the corrosion of steel, an equation is developed to estimate the corrosion rate of underground steel that varies with resistivity, pH value, moisture content and aeration of the soil. This formula, together with the IEEE Standard No. 80-1986, is used in the design of st...

Based on the National Bureau of Standards statistical data on the corrosion of steel (M. Romanoff, 1957), an equation is developed to estimate the corrosion rate of underground steel that varies with soil resistivity, pH value, moisture and aeration. This formula, together with IEEE Standard 80-1986, is used in the design of steel grounding. formul...

The problem of damaging overvoltages which result from using an oversized power factor correction capacitor is studied using digital simulation techniques. The overvoltages can occur during disconnection from the sources. The results are compared with results obtained from experiments performed on a 1.5 HP, 208 V, three-phase motor. The computer pl...