In the Danish and North European context the predominant means for efficient integration of variable re-newable energy are
• Strong transmission grids and interconnectors
• International electricity markets
• Flexible generations systems
• Specialized forecasting and operational planning tools (see chapter 7) In an Indonesian context some of these are more relevant than others.
Denmark is an integrated part of the North European electricity market and is heavily interconnected with a strong transmission grid. Denmark is a small country and the domestic electricity generation capacity is dominated by wind power and thermal plants fired by coal, gas and biomass.
The strong transmission grid and interconnectors enable Denmark to balance the variable wind power in a larger and more diversified electricity system in the Northern European region. The coupled electricity mar-kets ensure optimal utilisation of the available transmission capacity to supply demand with the cheapest possible generation capacity in the region. At the same time, the transmission system ensures crucial access to storage capacity in the hydro based electricity system in Norway.
For Indonesia, the international dimension on both transmission grids and electricity markets are very limited, and focus will have to be on domestic solutions. However, the domestic system is considerably larger than the Danish, and options for integration of variable generation can therefore still be obtained within the system.
The strong transmissions grids are still relevant with a larger share of variable renewable energy, which inevi-tably will create larger and more fluctuating flows on the transmission and distribution grids. Wind power will often be located far away from demand centres and substantial grid investments required to avoid cur-tailment.
For Indonesia, the flexibility of the thermal generation system is very important for the optimal utilisation of the wind power generation. The flexibility of the Danish thermal plants have increased substantially along with the massive integration of wind power, and sharing of Danish experiences on this process could be of great value for the Indonesian electricity utilities.
Page 89/103 Integration of Wind Energy in Power Systems Indonesia’s smaller island power systems might need focus on different and to some extent more
ad-vanced measures for integration, compared to larger power systems, as the European of which the Danish system is a part. For a case study on a smaller Island system, see chapter 10.3.1. As an example, batteries can be relevant for smaller isolated systems, while they are still too expensive compared to other options in large power systems. In smaller systems alternative generation can be costlier, which increases the value of batteries.
Other topics for ensuring sufficient power system flexibility include:
• Small systems can require other technologies as e.g. batteries for integration of variable genera-tion as opposed to the larger interconnected system.
• Power to heat – Industrial demand for process heat could provide demand flexibility if options for fuel shift are implemented (electric boilers as backup for alternative fuel based heat generation)
• Demand response, especially from larger customers
• Alternative providers of ancillary services
8.6.1 References
1. Ea (2015): The Danish Experience with Integrating Variable Renewable Energy. Study on behalf of Ago-ra Energiewende
2. Danish Energy Agency (2015): Flexibility in the Power System – Danish and European Experiences
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Grid connection of wind power plants in Denmark 9
This chapter will present the approval process for new onshore and offshore wind farms in Denmark. It likewise presents the grid codes for wind power plants and discusses how grid connection is handled in Denmark, and which technical studies are to be conducted before granting grid connection. At the end of the chapter a discussion is made regarding possibilities of requirement and technical studies that can be assessed as part of the approval process for grid connection of wind turbines into the Indonesian grid.
9.1 Approval process of wind power plants in DK
The process of granting a grid connection takes its point of departure in the type certification of a wind turbine, the electrical characteristics, the control and monitoring capabilities, the environmental assess-ment and approval of the site for the wind power plant. This chapter will address the electrical characteris-tics and the control and monitoring capabilities of the wind power plant facility.
The fundamental document for granting a grid connection in Denmark is the type certificate for the wind turbines applied in the facility, and the Danish registration in the DEA register of wind turbines allowed to be erected in Denmark. The rules and procedures are described the Danish Energy Agency's Executive Order on The Technical Certification Scheme for wind turbines no. 73 of January 25th 2013 and the appurtenant guideline. Wind turbines, including foundations, to be installed, maintained and serviced in Denmark must be certified according to the requirements in the Danish Certification Scheme. Based on the certificated wind turbines a wind power plant can be designed and approved by the relevant authorities.
Based on the executive order from the Danish government, the TSO (Energinet.dk) and DSO’s is obligated to bring the grid connection point in the proximity of the wind power plant site. This includes also offshore wind power plant sites. The only difference between granting a grid connection to an offshore wind power plant compared to an onshore wind power plant site is that the collection of endorsements involves a spe-cific authorisation for operating offshore as the offshore territory is owned by the Danish state.
When applying for a grid connection, the facility owner follows the process depicted in figure 9-1. The pro-cedure to follow is the same or granting the grid connection in the transmission or distribution system. The electricity undertaker (TSO/DSO) is the one to decide where the point of connection shall be allocated.
Based on a compliance test document approved by the grid operator a final operational notification can be issued and the facility owner is allowed to operate the facility.
Each third year a regular review / inspection of the actual compliance status is performed. Such an inspec-tion could result in an interim operainspec-tional notificainspec-tion and a new compliance test shall be performed after a maintenance or repair.
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Procesdiagram for grid connection of power generating facilities according to Technical Requirements specified in TR 3.2.x DSO/TSO
Request for grid connection of a Power Generating Facility
Collect and examines all documentation of the Power
Generating Module A new Power Generating Module is
build, or major changes to existing facilities is implementet. against the applicable network code.
Correspondence, meeting
All documents is archived in P360°
and work-flow starts
A operation report is made and send to the DSO. The report is
Figure 9-1: Grid connection granting procedure applied in Denmark.
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