1. PROJECT GRANTED UNDER INDO-EUROPEAN COOPERATION ON RENEWABLE ENERGY
8 March 2018
PROJECT GRANTED UNDER INDO-EUROPEAN COOPERATION ON RENEWABLE ENERGY

2. Policy and Industry Background
Offshore Wind Grid Integration Assessment for GJ & TN
Policy and Industry Background
Onshore Grid Development
Offshore Grid Development (scope)
System Operation
Technical and Regulatory Codes
The report is structured in the following subsections and sub-objectives:
Policy and Industry Background: To provide context to the report, and outline the environment under which the recommendations have been developed.
Onshore Grid Development: To address the steps to prepare the physical onshore grid for integration of offshore wind projects in Gujarat and Tamil Nadu.
Offshore Grid Development: To consider what is required to facilitate (new) offshore grid development for the integration of offshore wind projects in Gujarat and Tamil Nadu.
System Operation: To evaluate how the states in question will ensure stable system operation with increasing penetration of offshore wind and other Renewable Energy Sources (RES).
Technical and Regulatory Codes: To review the existing suite of the most relevant codes to ensure that they are suitable for development of offshore wind projects

3. STAKEHOLDERS IN THE POWER SECTOR
Responsibilities at the national level are mirrored at the state level. Important to share a common vision, harmonize plans and coordinate on infrastructure development.

4. ONSHORE GRID DEVELOPMENT
This section examines the key delivery risks of offshore wind development with respect to the current onshore grid planning and development
Assessment based on:
Review of inter-state and intra-state transmission planning process
National Electricity Plan (Generation & Transmission), 2016
Development of ‘Green Energy Corridors’ in Gujarat and Tamil Nadu
Intra-state grid developments in Gujarat and Tamil Nadu
Grid impact studies conducted by GETCO and TANGEDCO
Onshore grid infrastructure must be ready for OWF connection and power evacuation

5. ONSHORE GRID DEVELOPMENT
Integration of 500 MW OWF to Gujarat Transmission System
System study for 500 MW OWF at Pipavav at 400 kV level by 2020
Observations:
No system violations observed in load flow and contingency power flows in peak loading conditions
System violations observed in load flow and contingency power flows in off-peak loading conditions
Fault current levels are within the allowed short-circuit ratings
OWF curtailment might be necessary during off-peak conditions

6. ONSHORE GRID DEVELOPMENT
Integration of 500 MW OWF to Tamil Nadu Transmission System
System study for 500 MW OWF at 400 kV level in Samugarengapuram S/S by
Observations:
Load flow, contingency analysis, and short-circuit analysis show no system violations
The study considers several network development cases in a timely fashion and impacts of delay or non-delivery of any of the cases could undermine the feasibility of power evacuation

7. ONSHORE GRID DEVELOPMENT
Based on the assessment of the challenges and risks for onshore grid development, broad areas of recommendation are made below:
Barrier
Mitigation
Key Stakeholders
Offshore wind not included in current grid planning scenarios
Formulate state and national targets for offshore wind
Include offshore wind development scenarios in long term planning
MNRE, MoP
CEA, CTU and STUs
Delayed delivery of necessary onshore grid reinforcements causing power export constraints
Prioritise anticipatory investment in grid expansion (e.g. Green Energy Corridors)
CTU and STUs
Onshore grid infrastructure must be ready for OWF connection and power evacuation

8. OFFSHORE GRID DEVELOPMENT
This section examines the offshore power system, and its key components, their characteristics and potential configurations.
Assessment based on international standards, best practices and lessons learnt from mature offshore wind markets.

9. OFFSHORE GRID DEVELOPMENT
Key Design Considerations
Technical Limitations of Assets: e.g. continuous current rating (installation dependent), voltage operating range, fault levels etc.
Compliance: With local codes, standards and regulations.
Electrical Losses: Typically in the range 2-5% depending upon the export voltage and distance offshore. Valuation depends upon location of the metering and the allocation of transmission losses to different parties.
System redundancy and Resilience: Due to the elevated capital costs, offshore transmission systems are generally not designed fully (n-1) redundant, therefore the risk exposure to single points-of-failure (e.g. submarine transmission cables) must be carefully considered and mitigated in design and specification.
Typical Electrical Concept Design Development Process

10. OFFSHORE GRID DEVELOPMENT
Offshore grid systems are very similar to traditional onshore grid systems, but there are subtle differences in the nature of components and their ratings and application.
At present, there is limited experience in India for the planning, design and construction of offshore transmission systems.
Recommendations
Short term: International consultants may fill the competence gap
Long term: Develop a roadmap for development of local resource pool

11. OFFSHORE GRID DEVELOPMENT
When developing an offshore transmission system one must consider the topology of the offshore grid such that grid connections can be developed economically, in an incremental fashion, with due regard for ‘future proofing’ of the transmission system.
Three connection topologies are discussed in the report, together with a case study for each.
Radial: Each individual offshore wind farm connects to the onshore transmission via its own dedicated transmission link.
Clustering: Multiple wind farms are located geographically close enough to share transmission infrastructure
Integrated/Meshed: This concept has multiple offshore interconnections between projects with a diversity of onshore connection points. Characteristics closely resemble onshore grid topology.
The first offshore wind projects in India are likely to use a radial grid topology, but a clustering or integrated approach might be more suited for future developments.

12. OFFSHORE GRID DEVELOPMENT
Three regulatory models of offshore grid delivery and ownership are compared.
Model
Features
Key benefit
Countries
Generator model
The developer is responsible for the construction of the offshore grid connection and bears its entire cost
High incentive to implement a cost-efficient connection and ensures coordinated development of wind farm and offshore grid
Sweden
TSO model
The transmission system operator (TSO) is responsible for extending the grid to reach the wind farm
Allows for coordinated long term planning of offshore grid expansion
Germany, France, Netherlands
Third party model
A tender is run to appoint a third party as the Offshore Transmission Owner (OFTO) to build, own and operate the connection asset between the wind farm and the onshore transmission network
Allows for competition and companies to specialise in their operations UK
Each model has its advantages and disadvantages.
The choice of model determines the cost and risks borne by the various stakeholders, and so it is important to have a clear policy in place.

13. OFFSHORE GRID DEVELOPMENT
Based on the assessment of the challenges and risks for offshore grid development, three broad areas of recommendation are made.
Barrier
Mitigation
Key Stakeholders
No policy exists for delivery and ownership of offshore transmission systems.
Select either generator built or TSO built model for ownership of the first offshore wind projects
Initiate a Central Working Group to frame an enduring national offshore transmission policy
CEA, CTU, STUs
MoP, MNRE, CEA
No framework exists for offshore transmission network planning.
Initiate a Working Group to evaluate the optimal transmission topology and system planning regime for Gujarat and Tamil Nadu.
There is limited experience in India for the planning, design and construction of offshore transmission systems.
International consultants may fill the gap in the short term.
A longer term roadmap for development of local competencies should be devised.
CTU, STUs

14. SYSTEM OPERATION
The objective of this section is to understand the current challenges in system operation with renewables and their implications on development and operation of offshore wind sector.
Approach:
Review of current operational issues at National level.
Review of specific system operational issues in Gujarat and Tamil Nadu.
Implications on development of OWF in Gujarat and Tamil Nadu.

15. SYSTEM OPERATION
RES are different from the conventional generators in various operational aspects:
Generation variability and intermittency
Forecasting errors
Lack of contribution to system inertia
OWF are slightly different from onshore wind and solar PV
Larger size
Higher capacity factor in operation
Better accuracy in generation forecasting
Better reactive power control
Better support to system ancillary services
OWF can positively affect the system operation

16. SYSTEM OPEARATION
Three key recommendations are drawn on system operational aspects
Barrier
Mitigation
Key Stakeholders
Incomplete/delayed enforcement of national action plan for facilitating large scale renewable integration
Rigorous follow-up and timely enforcement of identified mitigation measures
NLDC, RLDC, CTU
Uncertainty around the absolute level of grid curtailment at present and expected in the near future
Measure, report and set targets on curtailment levels
CERC, RLDCs, SERCs, SLDCs
Limited experience in system operation with increased penetration of RES
Review the international practices and implement knowledge exchange/ capacity building programs to fulfil the gaps in the short term
Long term roadmap for development of local competencies
NLDC, RLDCs, SLDCs

17. Three documents are reviewed:
TECHNICAL AND REGULATORY CODES
This section examines the key codes and processes which are crucial to the development of offshore wind farm
Three documents are reviewed:
Connection application process
Grid code
System reliability standards

18. TECHNICAL AND REGULATORY CODES
Three recommendations are drawn after the review of existing technical and regulatory codes and their suitability for offshore wind projects
Barrier
Mitigation
Key Stakeholders
The connection process does not specifically address offshore wind projects.
Publish guidance on connection application process for the first offshore windfarms.
CTU, STUs, CERC, SERCs
Grid codes do not specifically address specific characteristics of offshore wind and its transmission connection
Future code modifications should be reviewed considering the specific characteristics and quantum of power from offshore wind farms.
Review the need for a separate grid code or modifications specifically for offshore wind projects.
Clarify on the compliance boundary of OWF under individual grid code requirements
CEA, CTU, STUs, CERC, SERCs
Planning standards do not address reliability standards for offshore connections.
Clarify on the applicability of present planning standards and consider the need for an offshore specific set of planning standards.
CEA, CTU, STUs

19. CONCLUSION Four overarching themes are identified in the report
Delivery of existing RES action points
To facilitate the grid integration of offshore wind
To reduce delivery and curtailment risks
Offshore wind policy and code development
National and state level targets
Framework for delivery and ownership
Due considerations in technical and regulatory codes
Grid development planning
Inclusion of offshore wind in long term planning process
Strategic grid development studies
Competence and capacity building
Learning from international experience
International consultants for short-term capacity building
Local competence building plan for long-term capacity building

20. Q&A?
Open Discussion

21. This project is co-funded by the European Union
For more information please contact:
FOWIND Project Management Unit,