Krishan Kant

Adaptive harmonic cancellation scheme for voltage and frequency control of a single-phase two-winding SEIG

This paper presents the adaptive harmonic cancellation (AHC) scheme for Decoupled Voltage and Frequency Controller (DVFC) for a single-phase two-winding self excited induction generator (SEIG) based small uncontrolled hydro turbine driven off-grid generating system. This DVFC consists of a Voltage Source Converter (VSC) and a controlled auxiliary load. In this proposed scheme, the voltage and frequency of the system are controlled independently of each other. The AHC scheme inherently produces a pure filtered sinusoidal signal of the system voltage which is used as an input to the Frequency Estimation Block (FEB) to estimate the system frequency. The information about time period of the every cycle is used to create a 90° phase shift in the next cycle of SEIG output voltage in frequency adaptive quadrature unit template generation block. This quadrature signal is used to estimate the reactive power compensation requirement of the system. The proposed control algorithm of DVFC of SEIG is implemented using a Digital Signal Processor (DSP).

Control and Implementation of a Standalone Solar Photovoltaic Hybrid System

A control algorithm for a standalone solar photovoltaic (PV)-diesel-battery hybrid system is implemented in this paper. The proposed system deals with the intermittent nature of the energy generated by the PV array and it also provides power quality improvement. The PV array is integrated through a dc-dc boost converter and is controlled using a maximum power point tracking algorithm to obtain the maximum power under varying operating conditions. The battery energy storage system (BESS) is integrated into the diesel engine generator set for the coordinated load management and power flow within the system. The admittance-based control algorithm is used for load balancing, harmonics elimination, and reactive power compensation under three-phase four-wire linear and nonlinear loads. A four-leg voltage-source converter with BESS also provides neutral current compensation. The performance of the proposed standalone hybrid system is studied under different loading conditions experimentally on a developed prototype of the system.

Control and implementation of a standalone solar photo-voltaic hybrid system

A control algorithm for a standalone solar photovoltaic (PV)-diesel-battery hybrid system is implemented in this paper. The proposed system deals with the intermittent nature of the energy generated by the PV array and it also provides power quality improvement. The PV array is integrated with a DC-DC boost converter and controlled through a maximum power point tracking (MPPT) algorithm to obtain the maximum power under varying operating conditions. The battery energy storage system (BESS) is integrated with the diesel engine generator (DG) set for the coordinated load management and power flow within the system. The admittance based control algorithm is used for load balancing, harmonics elimination and reactive power compensation under three phase four-wire linear and nonlinear loads. A four-leg voltage source converter (VSC) with BESS also provides neutral current compensation. The performance of proposed standalone hybrid system is analyzed under different loading conditions using sim-power system (SPS) toolbox in MATLAB/SIMULINK and it is validated experimentally on a developed prototype of the system.

Space conditioning using evaporative cooling for summers in Delhi

Abstract The article examines the possibility of space conditioning the interiors of a multistorey office building in Delhi using evaporative cooling in the summer months of April, May and June. The temperature and humidity conditions obtained in a room of the building with direct evaporative cooling are studied by simulation. In this case study, the room is assumed to have a south-facing wall with a window and all other walls, ceiling and floor are interior partitions. The effect of number of air-changes per hour (ACH) from 1 to 40 and fresh-air bypass factor (BPF) 0% to 100% on performance is studied by simulation. The aim is to find whether some combination of ACH and BPF succeeds in keeping room conditions below 80% RH and temperatures between 27 and 31°C, depending on RH. It is found that the desired results are achieved by keeping the ACH and the BPF within certain limits depending on weather conditions. If the temperature and relative humidity of the ambient air are too high then a direct evaporative cooler cannot achieve comfort in the room. Appropriate combinations of ACH and BPF have to be selected to obtain the best results.

Thermal comfort in a room with exposed roof using evaporative cooling in Delhi

In this study, diurnal hourly values of temperature and humidity in a room, with its roof exposed to the solar radiation in the summer months of April, May and June in Delhi, and having a direct evaporative cooler, have been computed and compared with the values obtained if the roof is unexposed. It is seen that additional heat load due to exposure of the roof to the solar radiation can be taken care of by slightly increasing the flow rate of the evaporatively cooled supply air. For April and May, the resulting conditions of the room air can be brought within an extended comfort zone (ECZ) by selecting an appropriate air change rate (ACH) giving due consideration to the bypass factor (BPF) of the cooler. During the month of June, the ambient air is very hot and its humidity rises; the conditions of the room are not within the ECZ, although the discomfort is mitigated. The levels of thermal sensation, which may be obtained with a direct evaporative cooler, have been computed on a numerical scale (S) which is pertinent to hot-dry and warm-humid climatic zones in India.

Power quality improvement in isolated distributed generating system using DSTATCOM

This paper presents the control of a synchronous reluctance generator (SyRG) driven by a biogas/biomass diesel engine as a prime mover in a distributed power generating system. This generator is used as a source to feed linear and nonlinear loads. A three-leg voltage source converter (VSC) based distribution static compensator (DSTATCOM) is implemented using adaptive neutral network based control algorithm for harmonics suppression, load balancing and voltage regulation in three-phase three-wire SyRG system with a battery energy storage system. This control algorithm is used for extraction of active and reactive power components of distorted load currents. These components of load currents are used for estimation of reference source currents to generate the gating pulses of VSC used as DSTATCOM. The performance of DSTATCOM is observed satisfactory for this type of generating system under balanced and unbalanced loads.

A simplified configuration and implementation of a standalone microgrid

A standalone microgrid system consisting of a solar photovoltaic (SPV) array, diesel engine driven permanent magnet synchronous generator (PMSG) and a battery energy storage system (BESS) is analyzed with a composite observer (CO) based control methodology. The PV array fed boost converter is controlled for providing the maximum power of the SPV array at any given temperature and insolation level. The BESS and diesel generator (DG) are used to control the transfer of power in the system. The CO based control technique is used for estimation of active and reactive powers of the standalone system. A three-leg voltage source converter (VSC) with a BESS is used to provide load balancing, reactive power compensation, harmonics elimination capabilities under different loading conditions. The assessment of the proposed configuration is carried out under different conditions and it is validated experimentally on a developed prototype of the system.

Voltage sensorless control algorithm for power quality improvement in distribution network

In this paper, a voltage sensorless control algorithm based on voltage estimators is used to control the DSTATCOM (Distribution Static Compensator) for a three phase four wire distribution system. The control algorithm emulates the load and DSTATCOM collectively as a balanced resistive load on the supply system. This algorithm functions as an estimator and eliminates the voltage sensor requirement. This algorithm is derived for a modified topology of DSTATCOM in the system which advantages are described in this paper. Due to simplicity of the algorithm, it can be easily implemented with reduced calculation than other complex algorithms. This algorithm is very effective in mitigating the various power quality problems like large neutral current due to unbalanced or nonlinear loads, reactive power consumption, harmonics current injection, voltage regulation in the distribution system.

A Hybrid Diesel-Wind­PV-Based Energy Generation System With Brushless Generators

This paper presents an experimental implementation of a standalone microgrid topology based on a single voltage source converter (VSC) and brushless generators. The microgrid system is energised with different renewable energy sources namely wind and solar PV array. However, a diesel generator (DG) set and a battery energy storage system (BESS) are also used to maintain the reliability of the system. The proposed topology has the advantage of reduced switching devices and simple control. The implemented topology has DG set as an ac source. The wind generator and the solar PV array are dc sources which are connected to the dc link of the VSC. The BESS is also used at the dc link to facilitate the instantaneous power balance under dynamic conditions. Along with the system integration, the VSC also has the capability to mitigate the power quality problems such as harmonic currents, load balancing, and voltage regulation. A wide variety of test results are presented to demonstrate all the features of the proposed system.

Design and implementation of single voltage source converter based standalone microgrid

In this paper, a single VSC (Voltage Source Converter) based standalone microgrid is proposed consisting of a brushless SRG (Synchronous Reluctance Generator) based diesel engine-generator (DG) set, sensorless and brushless variable speed wind energy conversion and a battery storage. A simplified controller is designed and developed to regulate the voltage and frequency of the microgrid by coordinating all these sources. The mechanical sensorless control of WECS (Wind Energy Conversion System) is adding to the simplicity and low cost. The proposed controller of microgrid improves the power quality apart from voltage and frequency regulation. The proposed microgrid is tested under various disturbances such as static and dynamic load switching, unbalanced loads, varying wind speeds, and changes in reference power of DG set. The controller is performing well in all these cases. With only one VSC, the cost and complexity in control are reduced in proposed microgrid.