Peter P. Groumpos

An optimal sizing method for stand-alone photovoltaic power systems

The total life-cycle cost of stand-alone photovoltaic (SAPV) power systems is mathematically formulated. A new optimal sizing algorithm for the solar array and battery capacity is developed. The optimum value of a balancing parameter, M, for the optimal sizing of SAPV system components is derived. The proposed optimal sizing algorithm is used in an illustrative example, where a more economical life-cycle cost has been obtained. The question of cost versus reliability is briefly discussed.

Optimum matching of ohmic loads to the photovoltaic array

Optimum matching of loads to the photovoltaic (PV) generator is most desirable for more accurate sizing, higher system performance and maximum utilization of the costly solar array generator. The quality of load matching depends on the PV array characteristics, the load characteristics, and the insolation profile. A matching factor is defined as the ratio of the load energy to the array maximum energy over a one day period. Optimum matching is achieved by determining the optimal array parameters with respect to the load parameters. Optimization is done using direct-search techniques. Results show that the theoretical optimum matching factor for an ohmic load is 94.34%. For an electrolytic load the matching factor could reach 99.83%. A maximum power tracker can be eliminated if optimum matching is achieved.

Time-invariant BAS-decentralized large-scale linear regulator problem

The regulation of a decentralized large-scale linear system which consists of N subsystems S1, S2,…,SN interconnected with a subsystem S0 is investigated. Since in the state-space description the matrix describing the dynamics of this decentralized large-scale system consists of block elements depicting an arrow structure, the system is called a block arrow structure (BAS) decentralized large-scale system and its regulation problem is called a BAS-decentralized large-scale linear regulator problem. In this paper, the time-invariant BAS-decentralized large-scale linear regulator problem is mathematically formulated and a solution to this problem is given by developing a suboptimal linear state feedback controller with the features of (a) partial decentralization (utilizing the interconnections), (b) parallel implementation, and (c) structure flexibility so that the addition and/or deletion of any subsystems within the BAS model specifications does not require the solution of the problem from the beginning ...

Structural control of large scale systems

The design of stabilizing feedback controls for Large-Scale Systems often requires the general concepts of decentralization. In this paper, we present a structural framework for the multilevel stabilization problem of Large-Scale Systems. In this context, we address the stabilization of fixed modes via local and global feedback controls and develop a Dynamical Hierarchical approach to stabilization.

A nonlinear optimization approach to the load matching of stand-alone PV power systems

The problem of the optimum matching of PV array characteristics and electrical loads is investigated with a mathematical approach using nonlinear optimization techniques. The loads are categorized and mathematically defined as ohmic loads, general linear loads, and nonlinear loads. The objective is to optimize the ratio of the load input energy to the PV generator maximum allowable energy over a one-day period and determine the optimum load parameters using nonlinear optimization techniques. The optimum battery parameters are also determined. Optimum parameters for a number of case studies are presented. A maximum power point tracker may not be needed if optimum load matching is achieved.<<ETX>>

Techno-economical analysis of different concepts of photovoltaic stand-alone energy systems and applications

Abstract The purpose of this paper is to decide the best conceptual design of a solar Stand-Alone Photovoltaic (SAPV) energy system to power a food processing plant. Construction is expected to be at ASWAN near the High Dam artificial pool in the extreme south of Egypt (23.97°N). Twenty-two different conceptual designs using Photovoltaics are investigated with the aid of computer models. Flat-plate SAPV systems using silicon or GaAs solar cells accompanied either by a battery of flywheel storage method are some of these conceptual designs. Concentrating the sunlight with different types of concentrators using Solar Cell Array (SCA) of compatible silicon and GaAs types, accompanied by the above-mentioned types of storage are some of the other designs. In addition, a comparison between the global optimum SCA size and the largest subglobal SCA size designs is carried out. From this study, it is concluded that the flat-plate silicon solar cells, tilted toward the equator by site latitude angle, with a storage battery of the sodium-sulfur type represented was in general, the best techno-economical design (0·1727 U.S.

A NEW ALGORITHM FOR PV CONCENTRATORS VS. FLAT PLATE IN A DOUBLE TRACKING MODE

kWh −1 ). It is followed by the integrated photovoltaic/thermal system with a concentrator using Ga 1-x Al x As/GaAs solar cells accompanied by a storage battery of the above mentioned type (0·1860 U.S.

Viable Photovoltaic Systems Applied to Sunbelt Environments

kWh −1 . These results can be attained if 1986 hopeful hardware costs are achieved.

On the Subjective Evaluation of Protection-Ratios' Measurements for Co-Channel FM-TV Interference under Variable (S/N) Ratios

This paper presents a new algorithm to solve the difficult and challenging problem of making a decision as to determine the appropriateness of using either PV concentrators or flat plates systems designed to meet a load demand at any location. In using the concept of energy difference expressed in a simple and reliable relationship, the algorithm alleviates the need to compute simultaneously the availability of solar energies striking PV concentrators and flat plates. Furthermore, the comparison study is reduced to a simple and generic problem of performance analysis taking into account the energies availability, the cells performances and their economical factor expressed in a simple and unique relationship defined as the performance measure (PM). Finally, some results from simulation studies are discussed in subsequent sections.

A GENERIC APPROACH TO THE SHADOW EFFECT OF LARGE SOLAR POWER SYSTEMS

The realization of solar energy is inevitable and one way to attain its achievement is through photovoltaic technology. Viable applications for sunbelt environments using photovoltaic (PV) systems are investigated. Preliminary feasibility studies where some optimum sizings were obtained for sites of the Mediterranean area are presented. A number of possible applications are listed.