Cost Of Photovoltaic Arrays Research Articles

Trinary Hybrid Cascaded H-Bridge Multilevel Inverter-Based Grid-Connected Solar Power Transfer System Supporting Critical Load

Higher power rating solar photovoltaic systems are emerging in the power system owing to the reduction in the cost of photovoltaic arrays and environmental concerns of the conventional power generation systems. Multilevel inverters are reported at high power levels due to reduced switching frequency and increased efficiency. Cascaded H-bridge (CHB) multilevel inverters have been reported in the literature due to its redundant structure compared to other multilevel topologies. When CHBs with dc sources are in the ratio of 1:3, it is named as a trinary hybrid multilevel inverter, and it generates a maximum number of equal output voltage levels. In this article, a trinary CHB multilevel inverter-based grid-connected solar power transfer system using modified second-order generalized integral control is proposed. A two-stage solar PV system consists of a single-input-multiple-output single-ended primary inductance converter and two CHB structures per phase used to verify the proposed system. A modified second-order generalized integral control is presented for active power control and grid synchronization. The controller is designed to eliminate dc-offset from the sensed load currents and to ensure balanced, sinusoidal, and unity power factor grid currents. Moreover, the shunt-connected system mitigates the reactive power and harmonic demands of the local load, thus maintaining the grid current power quality within the standard prescribed by IEEE-519. The performance of the proposed system is validated with an experimental prototype, and the test results validate the theoretical claims.

A Novel Ferrite SMDS Spoke-Type BLDC Motor for PV Bore-Well Submersible Water Pumps

Photovoltaic (PV) powered submersible electric water pumps are becoming popular in remote rural areas, due to the nonavailability of grid connectivity. However, the initial cost of a PV system is high. Permanent magnet (PM) brushless dc (BLDC) motors are efficient compared to existing induction motors, which reduce the cost of PV array. However, steep increase in the cost of rare-earth magnets like NdFeB and SmCo makes the use of PM motor uneconomical for PV systems. Thus, the design of PM motors with ferrite magnets is gaining interest. These magnets have low remanence flux density and are brittle. Thus, flux concentration rotor topologies are desirable. The conventional spoke-type (ST) rotor is one such topology. However, flux leakage is one of its prime concerns. To negotiate this, a novel “semi-modular dual-stack” ST BLDC motor along with its parametric aided three-dimensional finite element method analysis is proposed for a PV-based 100 mm deep bore-well submersible water pump. The motor features minimum flux leakage irrespective of rotor bridge width. In addition, a lumped parameter thermal network is modeled for quick estimation of the winding temperature rise. A prototype motor is fabricated to ascertain the results obtained from simulations, and the experimental results are presented.

A novel analytical model for optimal sizing of standalone photovoltaic systems

This paper presents a novel analytical model for the determination of optimal sizing of standalone photovoltaic (PV) systems with least cost and predetermined reliability to satisfy load. Algebraic equations for optimal PV array area (Aopt), optimal useful battery storage capacity (Cu,opt) and the constant of integration (kopt) has been formulated. The proposed model provides the system output directly without going through the calculation of PV array capacity (Ca) and battery storage capacity (Cb). It is different from previous models, which only optimize the system parameters Ca and Cb without involving load. The isoreliability curves of proposed model are compared with other analytical and numerical methods with the pair of Ca and Cb in different environmental conditions without load involvement. The formulated model is also applied for the optimal sizing of a standalone PV system for domestic purpose at Kuching, Sarawak, Malaysia. The required optimal PV array area (Aopt) and useful battery storage capacity (Cu,opt) is determined with various load demands and loss of load probability (LLP). Proposed analytical model is more constructive due to incorporation of many useful variables namely desired LLP value, latitude and clearness index of location, load demand and unit cost of PV array and battery capacity. It is also rational in terms of power reliability and cost, and simple to implement for the size optimization of standalone PV systems as compared to existing models.

Maximum power transfer from a nonlinear energy source to an arbitrary load

A more general approach to the matching procedure of an arbitrary load to a nonlinear energy source is presented. The matching procedure is required to assure a maximum power transfer to the load. The matching system is modelled by a linear network, capable of transforming DC power as well as AC power, which is characterised by a transformer matrix. The load and energy-source time variations call for a transformer with a controlled time-variable transfer ratio (TVT). The matching procedure is analysed and discussed. As a practical case, the matching of a photovoltaic (PV) array to a DC motor is studied. The theoretical results are compared to experimental ones. These results allow the determination of the operation and the starting-torque gain (and its maximum value) of the drive system. The torque gain is defined as the ratio of the torque in a matched system to the one in the system without a matching device. By using the TVT it has been found that the torque gain depends on the characteristics of the energy source (say, a PV array) and the electric motor. This study shows in which cases the use of a matching device is recommended and what is the technical improvement of the system. The relatively low costs of the matching device (1–2%) compared with the cost of PV array also helps to determine the economic benefit.