P. S. Chandramohanan Nair

Demand for commercial energy in the state of Kerala, India: an econometric analysis with medium-range projections

Abstract Rapid growth in the demand for commercial energy in Kerala, a state in India, posed serious development constraints in the recent past. The crucial issue of managing this demand will be of great importance in formulating the future development policy of the state. This study analyses the requirement of three major forms of commercial energy in the state of Kerala (viz. electricity, petroleum products and coal). Sectorwise/productwise econometric demand models are generated using regression method. The primary regression models consisting of statistically significant key energy indicators have been fitted with ordinary least-squares (OLS) estimation. Models wherever required have been subsequently refined in the second stage computations by employing Cochrane-Orcutt transformation algorithm to remove the effects of auto-correlation. The accuracy of the models have been checked using standard statistical techniques and validated against the past data by testing for ‘expost’ forecast accuracy. Employing the models, medium-range projections of demand of the state for commercial energy till the year 2020 have been made. The policy implications and related key issues have been addressed. The study identifies the urgent need for special attention in evolving effective energy policies to alleviate an ‘energy famine’ in the near future.

Analytical search of problems and prospects of power sector through Delphi study: case study of Kerala State, India

This study attempts to review and analyse the critical issues that afflict the power sector of Kerala, a developing State in India. For this purpose a Delphi study, contacting experts in the field was conducted. The paper illustrates the process followed for the conduct of Delphi survey and evaluates the responses obtained. Consensus among experts could be arrived at on various issues related to Kerala power sector in two rounds of Delphi survey. The expert-opinion concluded on various issues is discussed in the context of the present energy shortage faced by the State. The experts participated in the Delphi survey unanimously stressed on the urgent need for an integrated approach in the power sector planning process of the State. They also emphasised on the imperativeness for exploiting the demand side management potential of the State to alleviate energy crisis in future. The study fetched informative and revealing results, which may aid to formulate and review future planning strategies for the expansion of power sector of the State.

Influence of power factor compensating capacitors on estimation of harmonic distortion

Introduction of a tariff system which also considers the harmonic injection level is gaining importance as a mechanism to limit the increasing levels of harmonics in power systems. Many researchers have proposed methods to quantify the harmonic power flow from both supply side and load side so that penalties for harmonic injection can be introduced into the tariff structure. The IEEE Standard 1459-2000 defines electric power quantities for nonsinusoidal waveform conditions. Any penalty system introduced for harmonic distortion should be designed to recover the losses due to it and at the same time the penalty should be legally and scientifically acceptable. It should be ensured that no penalty is imposed on a clean consumer who does not inject any harmonics into the system and follows recommended practices of power system management. This paper analyses some of the available methods to quantify the harmonic injections and also identifies cases where a non-polluting consumer is also penalised by these methods. Studies on the possibility of increased harmonic distortion due to attempts made for power factor compensation by traditional methods are presented in the paper. The effectiveness of IEEE Standard 1459 in such cases is investigated.

A novel method for recovery of drainage power from distribution transformers

Non-linear loads have become a larger percentage of the total load in commercial facilities. The use of non-linear loads results in excessive injection of harmonic components from the customer facility onto the utility power system. Conventional distribution transformers are of delta-star type, providing 3-phase 4-wire ac distribution. In such a case, the triplen harmonic currents caused due to non-linear loads get circulated in the primary delta winding. But this leads to increased power losses, temperature rise and subsequent de-rating as well as reduction in life of transformers. This paper proposes a novel method for recovering the drainage power which is normally wasted in the delta winding of the distribution transformer. The experimental studies conducted on a three kVA transformer shows that when the drainage power of delta winding is recovered it helps in improving the transformer efficiency and system power factor.

Estimation of supply side harmonics by using network impedance data

Separation of contribution from supply side and customer side in generation of harmonics in power system is an important problem to be addressed. This paper presents a method to estimate the harmonics present in the supply side by making a few measurements at the point of common coupling. The method involves determination of network harmonic impedance by a noninvasive procedure. The normal operation of the customer or the utility is not affected at any stage of the test and it can be performed on a continuous manner. The accuracy of the proposed method has been demonstrated through simulation studies. Further refinement of the method can lead to development of technically feasible harmonic tariff regime where only the actual contributors of harmonics have to pay the penalty.

An equivalent circuit model for star-star-delta_utilized distribution transformer

In the recent years there has been excessive use of nonlinear loads in power distribution network resulting in the injection of harmonics into the utility power system. The triplen harmonics due to non-linear loads circulate in the conventional delta-star distribution transformer resulting in excessive power losses. Star-star-delta_utilized transformer is a modified distribution transformer configuration suggested recently which helps in recovering and utilizing the power wasted due to circulating harmonics in the transformer delta winding. This is achieved by connecting a load across the zero potential terminals of the tertiary delta winding of the transformer. This paper presents a three phase equivalent circuit model for the star-star-delta_utilized transformer. The proposed dependent source model is simulated and compared with the performance of the available transformer model of MATLAB Simulink. The results show that at steady state the performance of the proposed model can replicate the performance of the Simulink model.

Analysis of star-star-delta_utilized transformer under balanced and unbalanced load conditions

For decades research has been going on to resolve the power quality issues. The usage of non-linear loads is contributing much harmonic content in the distribution system. In the conventional distribution transformer of delta-star configuration, this injected harmonic power is trapped in delta winding and is wasted as heat. This wasted power or drainage power is a threat to the transformer itself. This paper presents the recovery of drainage power using star-star-delta_utilized distribution transformer under varying load conditions in the secondary. A study on primary and secondary side THD, input and output power factor, current harmonics, harmonic power and efficiency is carried out for balanced and unbalanced load conditions. The simulations are carried out in MATLAB Simulink and the results are verified by experimenting on the hardware set up.

Determination of temperature distribution and reduction of life of a dry type three phase transformer

This paper reports the development of a numerical model which can predict the temperature distribution in a 5 kVA, 400/400 V, delta - star dry type three phase transformer. The numerical model has been developed using the Commercial Computational Fluid Dynamics Package FLUENT 6.3. Numerical simulations are carried out for different loads. In order to validate the numerical model, experiments are conducted by performing a short circuit test and the numerical results compare well with experimental data. Based on the numerically obtained hot spot temperature, the reduction of life of the transformer is determined using Montsinger Equation.

Prospects for sustainable development of Kerala state through the electricity sector policy interventions

Energy management at supply and end-use side and utilization of renewable energy resources are considered as the best options to provide more environment friendly energy to all without affecting the well being of future generations. Formulation of strategies which balances economic development against environmental protection and energy security is vital for sustainable development. This paper evaluates and compares the contributions of the electricity sector of Kerala towards a sustainable future during the period 1991-2011. Power system performance indicators used for the assessment represent the social, economical, and environmental aspects of sustainability. Evaluation is done based on the overall sustainability index (OSI) computed for the years 1991, 2001 and 2011 using benchmarks formulated from the Indian electricity sector performance indicators in the same periods. By examining the sustainability performance, this study identifies desired reforms and policy priorities to put the Kerala state on the sustainable development pathway.

Measurement and analyses of power quality problems associated with a grid having wind energy conversion systems

Like conventional power plants, wind power plants must provide quality power required to ensure the stability and reliability of the power system it is connected to and to satisfy the customers connected to the same grid. Although many operational aspects affecting wind power plant operation are to be discussed, this paper focuses on power quality problems in power system due to the presence of wind generator and possible methods to suppress it. Harmonics are of concern due to potential damage to both utility and customer load equipment. It also introduces unnecessary heat losses in the power system. There are two primary methods for controlling or eliminating harmonic impacts in wind power plants. (1) The method of avoidance during the design process of wind energy generator system (2) Designing harmonic filters based on presence of harmonics in the system. This paper aims at taking the real time measurement from a wind farm. Analyzing the measurement results, power quality problems can be identified and a suitable method for reducing the problems will be identified. In the already existing system, harmonic problems can be reduced by installing a filter.