Chinmoy Kumar Panigrahi

Application of an Advanced Repetitive Controller to Mitigate Harmonics in MMC With APOD Scheme

In a modular multilevel converter (MMC), the second and other even-order harmonics in the circulating currents are mainly due to the fluctuations in the capacitor voltages in the sub modules of the MMC. The increased circulating currents affect the system performance and threatens the safety operation of power devices. To mitigate the circulating currents, this article puts forward the application of an advanced repetitive controller with alternate phase opposition and disposition pulse-width modulation technique. The proposed controller was operated in tandem with a proportional integral controller for better results of circulating current harmonic suppression and then the stability analysis was analyzed by the Popov criteria. This method is very simple to implement and suitable for multiple harmonic mitigation. Computer simulations and experimental results on a prototype shows that the proposed controller is effective and easy to implement for MMCs.

Transient stability analysis using modified Euler's iterative technique

This paper presents a detailed analysis on transient stability in power system using modified Eulers iterative techniques. Transient stability studies are of prime importance while planning as well as control and operation of the system. To carry out the transient stability studies, the initial operating conditions of the system just before the disturbances should be known. All these initial conditions are obtained by load flow studies prior to the disturbances by proper load flow methods.

Differential evolution with Gaussian mutation for combined heat and power economic dispatch

This paper presents differential evolution with Gaussian mutation to solve the complex non-smooth non-convex combined heat and power economic dispatch (CHPED) problem. Valve-point loading and prohibited operating zones of conventional thermal generators are taken into account. Differential evolution (DE) is a simple yet powerful global optimization technique. It exploits the differences of randomly sampled pairs of objective vectors for its mutation process. This mutation process is not suitable for complex multimodal optimization. This paper proposes Gaussian mutation in DE which improves search efficiency and guarantees a high probability of obtaining the global optimum without significantly impairing the simplicity of the structure of DE. The effectiveness of the proposed method has been verified on five test problems and three test systems. The results of the proposed approach are compared with those obtained by other evolutionary methods. It is found that the proposed differential evolution with Gaussian mutation-based approach is able to provide better solution.

Design and simulation of a solar–wind–biogas hybrid system architecture using HOMER in India

The renewable energy sources are accompanied by certain constraints as reliability, availability and continuous generation. In India, biomass is considered as the second best suitable combination with other renewable energy sources. Both solar and wind are undependable renewable energies as they are unpredictable. Now the key to successful renewable energy harvesting lies in the selection of hybrid system architecture for power generation. In rural areas, light is usually unavailable and if it does, it is mostly an incandescent light used for household lighting instead of fluorescent. System reliability, economy and environmental issues are the three major issues for decentralised electrification. So, finding the best suited hybrid system configuration to overcome these constraints is the need of the hour. It is at this stage that HOMER comes into the picture. HOMER, abbreviated name of hybrid optimization model for electric renewable, successfully realises system configuration before its installation and works for on-grid, off-grid and stand-alone systems, which make it useful for rural to urban applications. It simulates and optimises the best suitable solution for a hybrid system and generates reports incorporating all the aspects in designing a system. Here, a typical hybrid system is considered and the implementation of HOMER software has been incorporated.

Dynamic economic load dispatch using classical and soft computing techniques

Power system operation involves generation, transmission and distribution which involves optimization procedure for ensuring economy, reliability, security and stability. Dynamic economic load dispatch involves an optimization procedure for minimization of fuel cost. Optimization is done by properly scheduling the generator according to the load demand. This paper proposes a comparative analysis of finding the minimum fuel cost considering valve point effects using classical method such as Lagrange multiplier method followed by an analysis using power world simulator and that with Differential Evolution Algorithm respectively.

Effect of irradiance onyield factor of solar photovoltaic plant — A case study

Now a days for different application, the alternate energy solution is the solar energy. It may be a standalone system to provide power to the remote area or it may be grid connected system. The isolated PV system is always connected to a storage device to store the surplus power when the available power output is sufficient. Whereas grid integrated PV systems are more reliable. As the PV power is directly injected to the grid so many issues arises during the interconnection because of intermittent nature of the input energy. The main reason for fluctuation power is change in irradiance in this paper an experimental study as well as a case study is carried out to find effect of irradiance on the yield factor of the solar power plant.

Unbalanced voltage effects and its analysis on an induction motor

In industries, induction motors are widely used because they are cheap, rugged, requires less maintenance, and easy to operate. Although reliable, yet they are subjected to different types of failures/faults. Unbalanced voltage supply to the induction motor is one such external fault which can result in problems like excessive heating due to more losses, over-voltages, mechanical oscillations, acoustic noise, etc. In this paper, the effect of unbalanced voltage supply on the induction motor performance in terms of speed, torque and current is discussed. The %THD (Total Harmonic Distortion) of torque under balanced condition is 66.72% which is less as compared to that of unbalanced condition where it is 3852.17% The experiment and analysis has been performed in Maltab Simulink and its result is presented here.

PMU implementation for a Wide Area Measurement of a power system

Communication between consumer and supplier in both the direction is the essence of Smart Grid. For such two way communication, advanced sensors are being used in the present grid to collect and analyze data from the grid network. Moreover, Critical events in the grid require real-time identification and real time response. Phasor Measurement Unit(PMU) is such an intelligent sensors which help in making the existing grid into intelligent, dynamic self-healing, self optimizing transmission and distribution grid. This paper presents an approach towards the Phasor measurement units which is less complex in design. With the recent development of technology in power systems, PMUs can play a key role in Wide Area Measurement System (WAMS) and thereby providing a new dimension to the power system monitoring. Out of various techniques used for Phasor estimation, Non-recursive DFT algorithm has been used in this paper since it is more stable. PMU is implemented and simulated in both software and hardware. It is designed with the help of NI LabVIEW software.

Intelligent computing based converter fault identification in line commutated high voltage direct current transmission line

Line commutated converter based high voltage transmission line suffers from converter faults where the converter experiences commutation failure of the device. This fault occurs when the ac voltage drops or the short circuit occurs and is more frequent in the inverter. The fast detection of a fault is essential because improper transferring of current from one device to another can cause stress on the device and interruption of transmitted power. In this paper, a fast scheme for protection against commutation failure due to decrease or faults in ac voltage is implemented using a fuzzy logic controller. The rectifier end data voltage and current signals are chosen as an input to detect the faults. This scheme has good selectivity, reliability, accuracy and robustness.

Fault detection in direct current transmission lines using discrete fourier transform from single terminal current signals

Line commutated converter based high voltage transmission line fault current rises instantly due to the absence of inductance as which is present in ac. In dc currents there is no natural current zero so interruption of current is difficult and therefore the focus of the paper is to identify the fault in less time so that trip command can be initiated to the dc breaker. The dc lines are economical for long length so at far end distance fault identification is essential. The converter control in dc transmission lines control the power and provides synchronous interconnection between two ac systems. The discrete Fourier transform is used to extract the dc current at rectifier end of the dc transmission line and the processed current is compared with the threshold value to identify the fault. The factors considering the effect of fault location and fault resistance are considered for the accuracy, reliability and selectivity.