Introduction to Electrical Studies for Solar PV
There are several electrical studies that must be carried out before interconnecting or integrating an on-grid solar photovoltaic (PV) systems to the existing electricity grid system. These power system studies are categorized as grid impact studies and are usually part of a feasibility study for the construction of an on-grid solar PV system project. Electrical studies or power system study for solar PV systems include load or power flow analysis, short circuit analysis and stability analysis. ETAP software is the most widely used in this mater. – Omazaki Engineering is a consultant who serves power system or electrical study or grid impact or interconnection studies for solar PV systems. Contact us if you are looking for PV grid impact study consultants for your project in Indonesia and South East Asia, please contact us by sending an email to cs@omazaki.co.id or by filling in the form in contact.
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What is Grid Impact Study for Solar Photovoltaic (PV) System?
Grid impact or integration of solar PV system study is all related activities to interconnecting solar PV systems to the existing electrical or grid systems. Activities are split into three (3) categories based on when the activities occur.
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PV System Power Flow Study
The objective of a power flow study is to determine if the flow of electrical energy from PV Plant to customers meets the loading requirements and all the grid code requirements in terms of voltage levels and active & reactive power flow. A power flow study is performed on a power systems modelling software like ETAP.
Inputs to the power flow study are one-line diagram of the networks, details of transmission lines, transformers, PV system, reactive power compensation devices and loads.
In network-wide PV System connection analysis, multiple scenarios of growing PV penetration levels are created, starting with a base year and projecting into the future.
In the PV connection study, the following combination of demand and PV generation scenarios is typically analyzed : maximum, minimum and average. This leads to some scenarios, out of which the two worst-case scenarios are minimum demand with maximum PV generation and maximum demand with maximum PV generation.
Power flow analysis provides two types of insights : impact on schedule of existing powerplant and performance of grid in emergency conditions.
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PV System Short Circuit Study
The objective of a short-circuit study is to determine the impact of PV Plant on the protection systems at the interconnections substations and existing equipment.
PV power plant provide limited short circuit power to the grid, so in general the maximum short circuit MVA due to addition of PV power plant rarely poses a problem. Nevertheless, this scenario must be simulated to ensure that all the existing protections system will work as planned.
Regarding minimum level of short circuit MVA, there may be problems. In cases in which the PV plant is located far away from load center, the grid in proximity of the PV plant is weak, which means that minimum short circuit MVA is low, it means that a fault on the grid that far away from PV plant interconnection point does not appreciably increase to the short circuit current at the PV plant interconnection point.
The result of a short-circuit study are used to verify if the existing protection system is adequate when a PV powerplant is connected to the grid, and need for strengthening of the grid at PV plant point of interconnection.
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PV System Stability Study
The objective of a stability study is to determine the response of the system to variety of disturbances. There are two type of studies:
- The transient stability study examines response to large disturbances
- Dynamic stability study examines response to small disturbance
Transient stability study
A transient stability study models all the elements of the power system, the control system of the plant and the relay settings of protection system.
Various scenarios are simulated that are related to:
- Types of disturbance – single phase to ground fault, three phase to ground fault, loss of PV plant and loss of load in proximity to the point of interconnection of PV plant
- Levels of solar generation and load – high solar and low load, high solar and high load and others
The PV plant connection transient stability study determines if introduction of PV plant in the grid will cause the frequency to dip below the limit set in grid code and the length of time for the frequency to recover is longer than specific in grid code.
Dynamic stability study
The impact of small disturbances in the grid is analyzed using dynamic stability studies. As opposed transient studies that are modelled in the time-domain, dynamic studies are modelled in the frequency domain. A power system experiences change in load moment-by-moment. With PV plant in the grid, there is an increase in the variability and uncertainty of net load (demand load – PV plant production).
The key to a dynamic stability study is to examine the damping caused by small changes in net load and the subsequent response of the other plant on the grid. In a PV plant grid connection study, a variety of disturbances are simulated like net load variability, to determine if introduction of PV plant in the grid will cause significant changes to system.
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Contact Omazaki Engineering if you are looking for a consultant who provides ETAP power system or electrical studies (load flow, short-circuit or protection coordination) or grid impact study for your solar photovoltaic (PV) system project in South East Asia.
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Related Articles
- Grid Impact Study
- Power System Analysis Study
- Load Flow Study and Analysis
- Short Circuit Study & Analysis
- Protection Coordination Study
- Motor Starting Study and Analysis
- Power System Transient Stability Study
- Harmonic Study and Analysis
- Arc Flash Study & Assessment
- Power Quality Study & Assessment
- Voltage Drop Study & Analysis
- Voltage Imbalance (Unbalance) Study
- Electric Shock Protection Study
References
- https://www.worldbank.org/
- Alsema, E.A. (2000). Energy pay-back time and CO2 emissions of PV systems. Progress in Photovoltaics, 8(1), pp. 17-25.
- https://en.wikipedia.org/wiki/Grid-connected_photovoltaic_power_system
- DNV GL (2014), “Integration of Renewable Energy in Europe”. DNV GL, Imperial College London, NERA Economic Consulting, 12 June 2014. http://ec.europa. eu/energy/renewables/doc/201406_report_renewables_integration_europe. pdf.
- IRENA-ETSAP_Tech_Brief_Power_Grid_Integration_2015
- N. Stringer, N. Haghdadi, A. Bruce, J. Riesz, I. MacGill “Possible System Security
- Impacts of Distributed Photovoltaics Behavior During Voltage Disturbances”
- Presented at the IEEE PES General Meeting, Atlanta, US, Aug 2019.
- https://en.wikipedia.org/wiki/Low_voltage_ride_through
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