Reactive Power Dynamic Assessment of a PV System in a Distribution Grid

Samadi, Afshin; Ghandhari, Mehrdad; Söder, Lennart

doi:10.1016/j.egypro.2012.03.012

Cited by 29 publications

(17 citation statements)

References 7 publications

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“…cos φ pv,eq = m pv,eq P pv,eq − P th,eq + 1 (16) Q pv,eq = −P pv,eq 1 cos φ pv,eq 2 − 1 (17) where P pv,eq and Q pv,eq are active and reactive power of the equivalent PV model. In power flow simulations of this paper, the individual PV systems and the corresponding equivalent PV are considered as generation units with a power flow direction outward the units as shown in Fig.…”

Section: Model I: Zip/pv Equivalentmentioning

confidence: 99%

Static Equivalent of Distribution Grids With High Penetration of PV Systems

Samadi

Söder

Shayesteh

et al. 2015

IEEE Trans. Smart Grid

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High penetrations of photovoltaic (PV) systems within load pockets in distribution grids have changed pure consumers to prosumers. This can cause technical challenges in distribution and transmission grids, such as overvoltage and reverse power flow. Embedding voltage support schemes into PVs, such as standard cos φ(P) characteristic proposed by the German grid codes, may cause more changes in the steady-state behavior of distribution grids and, in turn, the transmission side. Accordingly, it is important to properly model active distribution grids to analyze the system impacts of these changes to plan and operate future smart power grids. However, due to the high dimension of distribution grids, considering a detailed distribution grid to study the transmission side or a fraction of the distribution grid is either cumbersome or impractical. Therefore, it is required to develop a reasonable equivalent that can fairly capture the dominant behavior of the distribution grids. The aim of this paper is to use gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of PV systems embedded with voltage support schemes. In the proposed model, the PV systems are aggregated as a separate entity, and not as a negative load, which is traditionally done. The results demonstrate the superior quality of the proposed model compared with the model with PV systems as the negative load.

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Section: Model I: Zip/pv Equivalentmentioning

confidence: 99%

Static Equivalent of Distribution Grids With High Penetration of PV Systems

Samadi

Söder

Shayesteh

et al. 2015

IEEE Trans. Smart Grid

Self Cite

View full text Add to dashboard Cite

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“…In reference [12], it was demonstrated that a PV-STATCOM can increase the power transfer limits of a transmission system. Reactive power support by one-phase and three-phase single-stage PV systems was also discussed by [13,14,15] focusing on control strategies to keep the converter within its operating limits. However, none of those works discussed the technical cost of operating a PV farm as a STATCOM.…”

Section: Motivationmentioning

confidence: 99%

Technical cost of operating a PV installation as a STATCOM during nightime.

Lourenço¹

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“…On the other hand, depending on time and weather variability, the simultaneous occurrence of excess intermittent renewable generation (i.e., wind and solar PV) and low demand would lead to loss of voltage regulation along with unexpected voltage-rise on the feeders due to reverse power flows [102]. As a fast response device, the inverter-based PV unit is allowed to inject or absorb reactive power to stabilize load voltages as per the new German grid code [103] while supplying energy as a primary task [101,104]. Other technologies such as synchronous machines used in biomass power plants, and Doubly-Fed Induction Generators (DFIGs) or full converter synchronous machines employed in wind farms are also capable of controlling reactive power while supplying active power [105].…”

Section: Grid Codes For Dg Integrationmentioning

confidence: 99%

“…This study assumes that inverter-based PV units are allowed to inject or absorb reactive power in compliance with the new German grid code [103]. Biomass gas turbines are modelled as synchronous machines.…”

Section: Generation Criteriamentioning

confidence: 99%

“…However, the roof-top PV has been considered as an example to validate the proposed methodology in this work. It is assumed that a PV unit provides active and reactive power at a lagging power factor of 0.9 which is compliant with the new German grid code [103]. The mean and standard deviation (i.e., µ and σ, respectively) for each hour of a day are calculated using the hourly historical solar irradiance data collected for three years, as provided in Table B.1 (Appendix B) [126].…”

Section: Solar Pv Modellingmentioning

confidence: 99%

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Smart integration of distributed renewable generation and battery energy storage

Hung¹

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Renewable energy (i.e., biomass, wind and solar) and Battery Energy Storage (BES) are emerging as sustainable solutions for electricity generation. In the last decade, the smart grid has been introduced to accommodate high penetration of such renewable resources and make the power grid more efficient, reliable and resilient. The smart grid is formulated as a combination of power systems, telecommunication communication and information technology. As an integral part of the smart grid, a smart integration approach is presented in this thesis. The main idea behind the smart integration is locating, sizing and operating renewable-based Distributed Generation (DG) resources and associated BES units in distribution networks strategically by considering various technical, economical and environmental issues. Hence, the aim of the thesis is to develop methodologies for strategic planning and operations of high renewable DG penetration along with an efficient usage of BES units.The first contribution of the thesis is to present three alternative analytical expressions to identify the location, size and power factor of a single DG unit with a goal of minimising power losses. These expressions are easily adapted to accommodate different types of renewable DG units for minimizing energy losses by considering the time-varying demand and different operating conditions of DG units. Both dispatchable and nondispatchable renewable DG units are investigated in the study. Secondly, a methodology is also introduced in the thesis for the integration of multiple dispatchable biomass and nondispatchable wind units. The concept behind this methodology is that each nondispatchable wind unit is converted into a dispatchable source by adding a biomass unit with sufficient capacity to retain the energy loss at a minimum level. Thirdly, the thesis studies the determination of nondispatchable photovoltaic (PV) penetration into distribution systems while considering time-varying voltage-dependent load models and probabilistic generation. The system loads are classified as an industrial, commercial or residential type or a mix of them with different normalised daily patterns. The Beta probability density function model is used to describe the probabilistic nature of solar irradiance. An analytical expression is proposed to size a PV unit. This expression is based on the derivation of a multiobjective index (IMO) that is formulated as a combination of iii three indices, namely active power loss, reactive power loss and voltage deviation. The IMO is minimised in determining the optimal size and power factor of a PV unit. Fourthly, the thesis discusses the integration of PV and BES units considering optimal power dispatch. In this work, each nondispatchable PV unit is converted into a dispatchable source by adding a BES unit with sufficient capacity. An analytical expression is proposed to determine the optimal size and power factor of PV and BES units for reducing energy losses and enhancing voltage stability. A self-correction algorith...

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Reactive Power Dynamic Assessment of a PV System in a Distribution Grid

Cited by 29 publications

References 7 publications

Static Equivalent of Distribution Grids With High Penetration of PV Systems

Static Equivalent of Distribution Grids With High Penetration of PV Systems

Technical cost of operating a PV installation as a STATCOM during nightime.

Smart integration of distributed renewable generation and battery energy storage

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