Estrutura delta para sistemas de irrigação PV

Este artigo apresenta um novo tipo de estrutura estática chamada delta, ΔS(60). Esta estrutura foi desenvolvida com o objetivo de obter perfis constantes de irradiância diária, extremamente importante nalgumas aplicações fotovoltaicas (como por exemplo, em sistemas de irrigação). Uma comparação do desempenho desta estrutura é feita com duas representativas do estado de arte atual: uma estrutura estática orientada ao Equador, S(25),e uma estrutura com seguidor de eixo horizontal, 1xh. É possível concluir que a hipótese de utilizar a ΔS(60) é particularmente interessante em sistemas de irrigação PV – a potência pico necessária com a ΔS(60) é menor que com a S(25), sendo a diferença ainda maior se consideramos o período de rega de maio a setembro

Viabilidade técnica de dois sistemas de irrigação fotovoltaica de alta potência em Espanha

Este artigo descreve dois sistemas de irrigação fotovoltaica, um de 360 kWp a caudal variável, instalado em Vilhena e outro de 160 kWp a caudal e pressão constante, instalado em Valhadolide. O objetivo deste artigo é apresentar cada um dos sistemas (componentes e modo de operação) e fazer uma primeira avaliação técnica dos mesmos. Através dos dados que foram monitorizados durante 2017 é analisada a performance e são apresentados alguns resultados relativos à operação e eficiência dos sistemas. Em Vilhena o PR do sistema foi de 0.65, sendo este valor inferior em Valhadolide (0.57). Os PRs hidráulicos são, respectivamente, 0.43 e 0.42

Sobre el número de módulos fotovoltaicos en serie para aplicaciones de riego

En sistemas de riego fotovoltaico la tensión mínima en el bus de continua del variador de frecuencia (VF) es impuesta por la tensión necesaria a la entrada de la moto-bomba. Así, siempre que esta tensión es más grande que la tensión del punto de máxima potencia del generador fotovoltaico parte de la energía que este podría entregar no se utiliza. El objetivo de este trabajo es estudiar estas pérdidas para 20, 21 y 22 módulos en serie (para módulos de 60 células en serie). Se puede concluir que si no hay caídas de tensión entre el VF y la moto-bomba las pérdidas son depreciables. Sin embargo, el aumento de estas pérdidas lleva a un incremento del porcentaje de pérdidas en energía fotovoltaica. Además, se verifica un aumento de las pérdidas con el incremento de la temperatura de célula

Economic results of the five MASLOWATEN demonstrators

MASLOWATEN Project aims at the large scale demonstration of the technical and economic feasibility of efficient and intermittency-free PV pumping systems for irrigation, allowing 100% renewable energy consumption. The main objectives of the Project are (i) to reduce 30 % of the water consumption, (ii) to achieve significant savings (at least 50%) for the farmers, in terms of energy costs and (iii) the market uptake and replication of a new green product consisting of PV Irrigation systems consuming 100% renewable electricity. In fact, MASLOWATEN Project has currently 5 demonstrators operating in the facilities of four different types of end-users: farmers, cooperatives, irrigator communities and agro-industries. The technology developed in the scope of the Project was then adapted to the reality of each farm and not the other way around which, in turn, makes clear the possibility to adapt the referred technology to each farmer?s reality. According to the Technical Specifications developed under MASLOWATEN project four criteria need to be met in a PV irrigation system: a) Integration of the PV system in the pre-existing irrigation system; b) Ability to support problems related to the PV power intermittences; c) Matching PV production and irrigation/water needs; and d) Ensuring the reliability of the system for at least 25 years

Performance of a 40 kWp PV irrigation demonstrator combining variable and constant pressure pumping

This paper describes a 40 kWp PV irrigation system combining variable frequency and constant pressure pumping installed in Sardinia, Italy. The objective of this paper is to present the design, as well as the implementation of the system. Moreover, monitoring data from 2017 irrigation season, from June to the end of October is analyzed and some first results are presented. During this period, the PV irrigation system pumped a total of 20574 m3

Estrutura delta para sistemas de irrigação PV

Este artigo apresenta um novo tipo de estrutura estática chamada delta, ΔS(60). Esta estrutura foi desenvolvida com o objetivo de obter perfis constantes de irradiância diária, extremamente importante nalgumas aplicações fotovoltaicas (como por exemplo, em sistemas de irrigação). Uma comparação do desempenho desta estrutura é feita com duas representativas do estado de arte atual: uma estrutura estática orientada ao Equador, S(25),e uma estrutura com seguidor de eixo horizontal, 1xh. É possível concluir que a hipótese de utilizar a ΔS(60) é particularmente interessante em sistemas de irrigação PV – a potência pico necessária com a ΔS(60) é menor que com a S(25), sendo a diferença ainda maior se consideramos o período de rega de maio a setembro

Economic validation of large power PV irrigation systems

This paper presents an economic evaluation of large-power PV irrigation systems (from 40 to 360 kWp) installed in Mediterranean countries, evaluating the economic feasibility of substituting or reducing their current energy sources (diesel or electrical grid) with a Photovoltaic (PV) generator and also an economic assessment based on PVIS simulated for ECOWAS region is also presented. In the first case, five PV irrigation systems, operating in Portugal, Spain, Italy and Morocco were considered and two energetic scenarios were created in order to do the economic analysis (Optimistic and Pessimistic Scenario). The normalized Net Present Value (NPV) values are in the 2.3-3.8 €/Wp range, Internal Rate of Return (IRR) values are in the 10-16% range and Payback Period (PBP) values are in the 7-11 years range. Finally, the Levelized Cost of Energy (LCOE) values for PV irrigation systems the values are in the 0.05-0.20 €/kWh range, which represents a percentage reduction of 34-67% % if compared to the actualized cost of the previous energy source. Regarding the second case, seven countries from the ECOWAS region were considered and two irrigation operating modes were compared (pumping to a water tank or at constant pressure). NPV values are in the 0.28-35.2x105 € range, (IRR) values are in the 8-47% range and (PBP) values are in the 2.1-10 years range. LCOE for PV irrigation systems are in the 0.04-0.15 €/kWh range, which represent percentage savings of 30-84% if compared to diesel-powered and gridpowered systems

An assessment of the proportional-integral control tuning rules applied to Photovoltaic Irrigation Systems based on Standard Frequency Converters

In this work, a systematic study of different tuning rules of proportional-integral (PI) control parameters applied to Photovoltaic Irrigation Systems (PVIS) based on Standard Frequency Converters (SFCs) has been carried out. A laboratory system has been implemented to obtain the PI control parameters by means of the most widely accepted tuning rules in control systems. Based on the step-input response modeling, we have been applied the tuning rules of Ziegler-Nichols (ZNs), Chien-Hrones-Reswick (CHR), Cohen-Coon (C-C), Lambda and AMIGOs. Based on frequency response modeling we have been applied the tuning rules of Ziegler-Nichols (ZNf) and AMIGOf. The PI controller parameters obtained from these tuning rules have been evaluated by performing two types of tests: start-up and sudden drop of the available PV power. The experimental results show that the parameter sets obtained by the ZNs, CHR and AMIGOf rules are the only ones that pass all the start-up tests and that the tests of sudden drop of the available PV power are only passed by the configuration obtained by the AMIGOf rules. Therefore, it has experimentally verified that the AMIGO tuning rules based on the frequency response modeling are the only ones that provide adequate values for the PI control parameters for PV irrigation systems

A 140 kW Hybrid PV-Diesel pumping system for constant-pressure Irrigation

This paper describes a 140 kWp hybrid PV-diesel pumping demonstrator for constant pressure irrigation in a 200 ha olive tree plantation at Herdade de São Bernabé, Alter do Chão, Portugal. The PV system was installed in June 2016 and has been working since then. A previous system fed exclusively by a diesel generator was already implemented, and the PV part was added, maintaining unchanged all the irrigation part of the system. The new system configuration and control logic, as well as the implementation in the field, are detailed in this work. The first results obtained from monitoring data during June, July and August 2017 show that 125760 m3 were pumped (55179 m3 with photovoltaic) during 590 irrigation hours. The PR during irrigation hours is 0,42 and PV penetration 43%

Large-Scale Hybrid PV-Grid Irrigation System

This paper describes a 120 kWp hybrid PV-grid irrigation system at constant pressure, which has been installed in a 233 ha farm devoted to the intensive cultivation of olive trees in Tamelelt, Morocco. The description includes important information regarding system configuration, working control and implementation. In addition, monitoring data between July 18 and August 31, 2017, is analyzed and first results presented. The system has been working according to the initial expectations since July 2016 and in the 45 days currently under analysis, the number of irrigation hours were 251, being 71% the PV penetration. The PR of the system is 0,33, while the PR during irrigation hours increases to 0,69