DISTRIBUTION IMPACT STUDY
(DIS) GUIDELINE Guideline for Studying the Impact of Rooftop PV-Systems on Distribution Networks in the Philippines
www.renewables-made-in-germany.com
Imprint
Authors
Moeller & Poeller Engineering (M.P.E.) GmbH
December 2013 (Version 1)
Publisher
Deutsche Gesellschaft fr Internationale Zusammenarbeit (GIZ) GmbH
On behalf of the
German Federal Ministry of Economic Affairs and Energy (BMWi)
Contact
Deutsche Gesellschaft fr Internationale Zusammenarbeit (GIZ) GmbH
Kthener Str. 2, 10963 Berlin, Germany
Fax: +49 (0)30 33 84 24 22 253
Email: [email protected]
Web: www.giz.de/projektentwicklungsprogramm
Web: www.renewables-made-in-germany.com
This guideline is part of the Project Development Programme (PDP) South-East Asia. PDP South-East Asia is implemented by the Deutsche Gesellschaft fr Internationale Zusammenarbeit (GIZ) GmbH on behalf of the German Federal Ministry of Economic Affairs and Energy (BMWi) under the renewables Made in Germany initiative. More information about PDP and about renewable energy markets in South-East Asia can be found on the website www.giz.de/projektentwicklungsprogramm.
This publication, including all its information, is protected by copyright. GIZ cannot be liable for any material or immaterial damages caused directly or indirectly by the use or disuse of parts. Any use that is not expressly permitted under copyright legislation requires the prior consent of GIZ.
All contents were created with the utmost care and in good faith. GIZ assumes no responsibility for the accuracy, timeliness, completeness or quality of the information provided.
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Content
1 Background 1
1.1 Purpose of this Document 1
1.2 Application Process 1
2 PV-Inverters 3
2.1 Technology 3
2.2 Requirements of the Technical Interconnection Rules according to the Net-Metering Standard 3
2.3 Technical Characteristics of PV-Inverters 5
3 Distribution Impact Studies (DIS) Technical Scope 5
3.1 Technical Scope according to the Distribution Code 5
3.2 Impact on Thermal Component Ratings and Voltage Variations on LV-feeders 6
3.2.1 General Study Methodology 6
3.2.2 Example 6
3.3 Impact on Thermal Component Ratings and Voltage Variations on LV-feeders 9
3.4 Coordination of Protection System 10
3.5 Harmonic Performance 10
3.6 Flicker 12
References 13
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List of Figures
Figure 1: Workflow of Application Process (taken from [4]) 2
Figure 2: DC-Source with Inverter 3
Figure 3: Load Profile, PV-profile (1kWp), Residual Load Profile 6
Figure 4: Load Profile, PV-profile (4kWp), Residual Load Profile 7
Figure 5: Load Profile, PV-profile (6kWp), Residual Load Profile 7
Figure 6: Example of a LV-feeder with PV generation 8
Figure 7: Residual Feeder Load for different PV-injection scenarios 8
Figure 8: Voltage at the end of the LV-feeder for different PV-injection scenarios 9
Figure 9: Example of a LV-feeder with PV generation 11
Measurement
W Watt Wp Watt peak Wh Watt hour
kW Kilowatt kWp Kilowatt peak kWh Kilowatt hour
MW Megawatt MWp Megawatt peak MWh Megawatt hour
GW Gigawatt GWp Gigawatt peak GWh Gigawatt hour
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List of Acronyms
DAS Distribution Assets Study
DIS Distribution Impact Study
DSOAR Distribution Service and Open Access Rules of the Philippines
DU Distribution Utility
IGBT Insulated-gate bipolar transistor
IGCT Integrated gate-commutated thyristor
LV Low Voltage
MV Medium Voltage
PV Photovoltaics
QE Qualified End Unser
TDD Total Demand Distortion, THD of current
THD Total Harmonic Distortion
VDE German Association for Electrical, Electronic and Information Technologies
DISTRIBUTION IMPACT OF ROOFTOP-PV
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1 Background
1.1 Purpose of this Document
On 27 May 2013, the Energy Regulatory Commission adopted ERC Resolution 09, Series of 2013 approving the
Rules Enabling the Net-Metering Program for Renewable Energy. This resolution was published on 10 July 2013 in
newspapers of general circulation in the country and took effect 15 days thereafter. Thus, the Net-Metering Rules
took effect in the Philippines on July 24, 2013.
Net-metering allows customers of Distribution Utilities (DUs) to install an on-site Renewable Energy (RE) facility
not exceeding 100 kilowatts (kW) in capacity so they can generate electricity for their own use. Any electricity
generated that is not consumed by the customer is automatically exported to the DUs distribution system. The DU
then gives a peso credit for the excess electricity received equivalent to the DUs blended generation cost, excluding
other generation adjustments, and deducts the credits earned to the customers electric bill.
As part of the technical evaluation the DU has the option to perform a Distribution Impact Study (DIS) to
assess the ability of the Distribution system to safely and reliably accommodate a proposed interconnection of a
generation source and if any upgrades may be required.
This document will:
Define a guideline for the typical scope of DIS for Renewable Generators that will be connected under a
Net-Metering Agreement.
Define criteria allowing a decision whether DIS will be required or not.
The guidelines presented in this document are mainly based on international practice for the connection of
renewable generation to LV networks and propose simplified methods for reducing time and effort needed for
determining the impact of renewable generators on LV networks.
1.2 Application Process
The Application Process for Renewable Generators that shall be connected to LV-networks of the Philippines is
defined in the Net-Metering-Rules [1] and further explained in [4].
It covers the whole process, starting from a written request for receiving information and data required for the
submission of an application and ends with the signature of a connection agreement (see Figure 1).
This application process further defines that the Distribution Utility (DU) shall decide whether the execution of a
Distribution Impact Study (DIS) and/or a Distribution Assets Study (DAS) shall be required in accordance with the
Distribution Service and Open Access Rules of the Philippines (DSOAR) [2].
The DSOAR [2] further specify the purpose of DIS and DAS:
A DIS shall identify whether any distribution constraints, re-dispatch options, additional dedicated
Connection Assets, or Distribution System upgrades shall be required to provide the requested service.
Based on the results of a DIS, a DAS shall be executed with the purpose of identifying in detail additionally required
distribution assets and corresponding costs.
According to DSOAR [2], a DIS is always executed by the Distribution Utility (DU), whereas a DA can either be
executed by the applicant itself or the DU. The Net-Metering rules [1] do not explicitly mention the possibility that a
DAS can be executed by a Net-Metering applicant.
The costs of a DIS and a DAS always have to be covered by the applicant.
The Philippine Distribution Code [3] specifies the scope of DIS as follows:
The Distributor shall conduct Distribution Impact Studies to evaluate the impact of the proposed
connection or modification to an existing connection on the Distribution System. The evaluation shall
include the following:
o Impact of short-circuit infeed on the distribution equipment
o Coordination of Protection System
o Impact of User Development on Power Quality
The Distributor may disapprove an application for connection or a modification to an existing connection
to the Distribution System if it is determined through the Distribution System Impact Studies that the
proposed connection or modification will result in the degradation of the Distribution System.
Figure 1: Workflow of Application Process (taken from [4])
When comparing the definition of DIS in the DSOAR [2] and the Distribution Code [3] a slight difference with
regard to the purpose of DIS can be noticed:
DISTRIBUTION IMPACT OF ROOFTOP-PV
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According to DSOAR, a DIS has to be carried out for identifying required network upgrades, which in turn
will avoid any degradation of the performance of the distribution system, whereas
According to the Distribution Code, the result of DIS will be used for decide whether a connection will be
permitted or not.
Because the Net-Metering Rules [1] explicitly refer to DSOAR [2] in section 5.5 of [1], it can be assumed that the
result of DIS will be used for defining required distribution network upgrades (through DAS) and not for rejecting
an application without having analyzed potential network upgrades.
2 PV-Inverters
2.1 Technology
Figure 2: DC-Source with Inverter
Photovoltaic (PV) modules produce a DC-voltage and a DC-current that is converted
