Maximum power injection acceptance in a residential area

The number of installed distributed generation (DG) in residential areas rapidly increases, specifically in the form of photovoltaics (PV), causing some undesired side effects such as voltage rise. Overvoltage can damage critical loads, but is also disadvantageous for the owner because inverters switch off in case of overvoltage, resulting in output loss. Voltage limits are investigated through calculation and simulation of the voltage profile in a typical low voltage (LV) grid by using load data. Insolation data is used for the particular case of PV. This paper presents practical guidelines for the maximum power acceptance in a residential distribution network and the estimation of PV production loss due to overvoltage

Introducing small storage capacity at residential PV installations to prevent overvoltages

Low voltage distribution feeders are designed for unidirectional energy supply from transformer to consumer. However, the implementation of small-scale PV production units on local utilities may result in bidirectional energy flows. The simultaneous power injection at sunny moments may cause a serious voltage rise along the feeder. These overvoltages may not only damage critical loads but also switches PV inverters off causing loss of green energy at the most productive moments. This paper presents a method to limit the voltage rise by introducing small battery buffers at local production sites. A smart inverter decides whether the PV energy is injected in the grid or buffered in the batteries. The relation between battery buffer size and overvoltage reduction is presented for a typical Belgian residential distribution feeder. The influence of the buffer along the feeder is calculated by working with synthetic load profiles and solar irradiation data

Is zonne-energie economisch interessant?

Nu de steunmaatregelen voor zonne-energie verminderen, wordt de vraag of deze technologie economisch rendabel is nog belangrijker dan voorheen. Binnen verschillende kenniscentra, zowel wereldwijd als in Vlaanderen, wordt hierop onderzoek verricht. Zo wordt ook aan Lemcko, het elektrotechnisch expertisecentrum van de Hogeschool West-Vlaanderen departement GKG (voormalig PIH), diepere studie hierop doorgevoerd. Lemcko is een gevestigde waarde binnen de onderzoeks- en dienstverleningswereld in het domein van de netkwaliteit, energie-efficiëntie en implementatie van hernieuwbare energiebronnen op het distributienet. Het onderzoek doorgevoerd binnen Lemcko is niet alleen van wetenschappelijke en technologische inslag, maar ook economische aspecten worden onderzocht. Deze bijdrage werpt een kritische blik op de economische haalbaarheid van zonne-energie-projecten. Hieruit moet blijken dat dergelijke projecten niet steeds zo economisch interessant zijn als het gros van de installateurs doet uitschijnen. Er dient dan ook doordacht omgesprongen te worden met de investering in dergelijke productie-eenheden

Gevolgen van de sterke groei van PV-panelen

Gezien de huidige regelgeving toelaat dat iedereen, zonder toestemming van de netbeheerder, hernieuwbare energie op het net mag injecteren met een vermogen kleiner dan 10kW, zal er in de nabije toekomst rekening moeten gehouden worden met problemen van netoverspanningen en het ongewenst uitschakelen van netgekoppelde invertoren. Door deze verhoogde netspanning worden de verhoopte opbrengsten van de hernieuwbare bronnen niet bekomen, en bovendien de vooropgestelde terugverdientijden niet gehaald. Het is eveneens niet ondenkbaar dat de schade op elektrotechnische installatieonderdelen om reden van deze verhoogde spanning ook verder zal toenemen

Implementatie van innovatieve duurzame energiebronnen en hun interactie op het distributienet

Het boek is een algemene situering van fotovoltaïsche energie, opgedeeld in twee grote delen: een technisch en een economisch georiënteerd deel. Het eerste deel behandelt de technische aspecten van de koppeling van decentrale productie op het distributienet. De verschillende onderdelen van een netgekoppelde fotovoltaïsche installatie worden een voor een uitgewerkt. Het tweede deel van dit boek heeft tot doel de lezer toe te laten om een oordeel te vellen of een instalatie economisch haalbaar is voor zijn situatie. Hierbij worden niet enkel de invloed van economische parameters maar ook van technische parameters onderzocht

Power injection by distributed generation and the influence of harmonic load conditions

The number of installed distributed generation (DG) in residential areas rapidly increases, specifically in the form of photovoltaics (PV), causing some undesired side effects such as voltage rise. Overvoltage can damage critical loads, but is also disadvantageous for the owner because inverters switch off in case of overvoltage, resulting in output loss. Since grid connected inverters essentially exhibit nonlinear behavior, harmonic interactions between large numbers of DG systems and the distribution network may occur. Also nonlinear loads inject harmonic currents and induce increased voltage drops over both phase and neutral conductors. This extra supply voltage drop can lead to an even more pronounced production loss of grid coupled inverters. This contribution gives some guidelines for the maximum power acceptance in a residential grid and the estimation of PV production losses due to overvoltage and discusses the influence of harmonic voltage drops

Preventing overvoltages in PV grids by integration of small storage capacity

The rapidly growing amount of distributed generation in low voltage distribution grids issues some undesired side effects. Simultaneous power injection may cause a serious voltage rise along the feeder. These overvoltages may not only damage critical loads but also switch off PV inverters causing loss of green energy at the most productive moments. This paper discusses the origin and different possibilities to limit this induced voltage rise. The option of introducing local energy buffering is further elaborated. The relation between buffer size and overvoltage reduction is presented for a typical Belgian residential distribution feeder. The influence of buffers along the feeder is calculated by working with synthetic load profiles and solar irradiation data

Economic evaluation of the influence of overvoltages and the integration of small storage capacity in residential PV-installations

Implementation of decentralized production units (PV-installations) on low voltage distribution feeders may result in bidirectional energy flow. Simultaneous power injection may cause voltage rise on the feeder. Due to regulations inverters need to switch off when reaching a certain voltage causing loss of production. Because this happens mostly on bright, sunny days production loss can be significant. This paper presents an economic comparison between a situation without production loss, with production loss due to overvoltages and the introduction of storage. The production is calculated based on synthetic load profiles and solar irradiation data. The economic feasibility is calculated based on realistic prices and taking into consideration all available government funding

Introducing small storage capacity at residential PV installations to prevent overvoltages

Low voltage distribution feeders are designed for unidirectional energy supply from transformer to consumer. However, the implementation of small-scale PV production units on local utilities may result in bidirectional energy flows. The simultaneous power injection at sunny moments may cause a serious voltage rise along the feeder. These overvoltages may not only damage critical loads but also switches PV inverters off causing loss of green energy at the most productive moments. This paper presents a method to limit the voltage rise by introducing small battery buffers at local production sites. A smart inverter decides whether the PV energy is injected in the grid or buffered in the batteries. The relation between battery buffer size and overvoltage reduction is presented for a typical Belgian residential distribution feeder. The influence of the buffer along the feeder is calculated by working with synthetic load profiles and solar irradiation data.status: publishe