Gd

G33 JB33 5

SkS>

G35 TB2L '

G36 TB36 5

System B

WF Station

Fig. 1. Sample structure of interna! electrical network of the 72 MW wind farm connected to the HV distribution network

There are different ways of connecting wind farms to the HV network depending, among other things, on the power level of a wind farm, distance to the HV substation and the number of wind farms connected to the sequencing lines. One can distinguish the following characteristic types of connections of wind farms to the transmission network:

• Connection in the three-terminal scheme (Fig. 2a). For this form of connection the lowest investment costs can be achieved. On the other hand, this form of connection causes several serious technical problems, especially for the power system automation. They are related to the proper faults detection and faults elimination in the surroundings of the wind farm connection point. Currently, this is not the preferred and recommended type of connection. Usually, the electrical power of such a wind farm does not exceed a dozen or so MW.

• Connection to the HV busbars of the existing substation in the series of lines (Fig. 2b). This is the most popular solution. The level of connected wind farms is typically in the range of 5 to 80 MW.

• Connection by the cut of the line (Fig. 3.). This entails building a new substation. If the farm is connected in the vicinity of an existing line, a separate wind farm feeder line is superfluous. Only cut ends of the line have to be guided to the new wind farm power substation. This substation can be made in the H configuration or the more complex 2

circuit-breaker (2CB) configuration (Fig. 3b). The topology of the substation depends on the number of the target wind farms connected to such a substation.

Substation A

Substation B

Substation A

Substation B

Substation B

Substation A

Fig. 2. Types of the wind farm connection to HV network: a) three terminal-line , b) connection to the busbars of existing HV/MV substation

Substation A

Substation B

Substation A

Substation B

Substation B

Fig. 3. Connection of the wind farm to the HV network by the cutting of line: a) substation in the H4 configuration, b) two-system 2CB configuration

• Connection to the HV switchgear of the EHV/HV substation bound to the transmission network. In this case one of the existing HV line bays (Fig. 4a) or the separate transformer (Fig. 4b) can be used. This form of connection is possible for wind farms of high level generating powers (exceeding 100 MW). The influence of such a connection on the proper functioning of the power protections is the lowest one.

Fig. 4. Wind farm connection to the power system: a) by the existing switching bay of the EHV/HV substation, b) by the HV busbars of the separate EHV/HV transformer

• Connection of the wind farm by the high voltage AC/DC link (Fig. 5). This form is most commonly used for wind farms located on the sea and for different reasons cannot work synchronously with the electrical power system. Using a direct current link is useful for the control of operating conditions of the wind farm, however at the price of higher investments costs.

System A HV

System B HV

System B HV

Fig. 5. Connection of the wind farm by the AC/DC link

Fig. 5. Connection of the wind farm by the AC/DC link

Due to the limited number of system EHV/HV substations and the relatively high distances between substations and wind farms, most of them are connected to the existing or newly built HV/MV substations inside the HV line series.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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