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European wind power integration study: the contribution from Greece

Objective

To investigate the integration of wind turbines in the National Grid. Identify the specific problems and limitations arising from the various wind farms that can be located in the mainland, Crete and some of the Cyclades islands.
A phase of the Wind Power Integration Study carried out by the Public Power Corporation (PPC), includes a analysis of:
wind potential assessment;
site selection procedure;
estimation of the installed wind farm capacity;
wind farm investment figures;
wind predictability and consequences.

The areas examined were considered ideal as far as wind potential concerned with annual wind speeds ranging form 6 to 9 ms{-1}. This data was verified experimentally by PPC and was considered accurate.

Great care was taken in selecting the sites which were classified in categories according to wind potential, easy access by road proximity to PPC power lines and sufficient distance from environmentally sensitive areas. The study included the maps and the exact locations of all the sites visited.

The possible power that could be installed is 61.5 MW for Crete and 93.0 MW for Cyclades. (Total of 154.5 MW). In order to arrive at these figures a triangular shaped wind farm lay out was used and a 300 kW wind turbine was considered.

Based upon the recent international tenders which was carried out by PPC, the investment cost for a wind farm comprising 225 kW machines came to 1786 ECCU/kW where as for a 300 kW machine came to 1400 ECU/kW.

A phase of the Wind Power Integration Study which was subcontracted to the National Technical University of Athens' Electric Energy Systems Laboratory, dealt with wind park grid interface and system stability problems.
The study examined 2 cases:
the islands of Andros, Tinos, Myconos and Syros interconnected to the national power system;
the island of Creteas an isolated system.

The connection of the total maximum wind power, which can be installed in the 4 islands of Cyclades (Andros, Tinos, Syros and Myconos) and was based on the Public Power Corporation's (PPC) relevant scenario, can be achieved without significant changes of the 150/66 KV network that has been scheduled for their interconnection to the national power system.

Specific studies (concerning load flow, voltage fluctuations and protection coordination problems) should be made for the connection of each wind park to the 15 of 20 KV network. Methods that can be applied to analyze the relevant problems are included in this report.

The connection of the total maximum wind power (61MW), which can be installed in Crete and was, also, based on PCC's relevant scenario, is permissible under the assumptions made in the study, especially concerning the rate of change of the wind power and the characteristics of the conventional units.

The validation of the assumptions concerning the behaviour of the wind speed considered in the study (specifically, the rate of power change and the correlation between wind parks at different sites), is of primary importance. Special measurements and considerable work must be done in the future, on this subject.

In all studied cases, for the estimation of the behaviour of the power system during wind power change, it was considered that the existing spinning reserve of the conventional power units exceeded the decrease of the wind power. Any different scenarios, including load shading, can be easily analyzed by the developed software.

The existence of the wind parks does not alter the dynamic stability of the power system (during short circuits or similar disturbances).

A small part of the study was devoted to the wind predictability energy credit calculation.
Following the first phase of the Wind Power Integration Study which has shown that wind energy can be cost effective for Greece, this study will focus on the specific technical problems that might arise from such an integration.

PPC, in close cooperation with the National Technical University of Athens will investigate the following:

1) System stability problems.
2) Wind predictability, potential and benefits.
3) Wind farm grid interface.
4) Wind farm cost and operation.

This way the economics of system integration can be fully evaluated. Also the project involves the exchange of information with other power companies of the EC on the topics of wind energy utilization.

NB: This contract is part of an important joint study on wind power integration that is specific for each European country. This group covers following contracts: JOUR-CT89-0022; JOUR-CT89-0023; JOUR-CT89-0028; JOUR-CT89-0029; JOUR-CT89-0030; JOUR-CT90-0041; JOUR-CT90-0042; JOUR-CT90-0043; JOUR-CT90-0044; JOUR-CT90-0049; JOUR-CT90-0088.

Coordinator

Public Power Corporation Greece
Address
Alternative Energy Forms Department, Navarinou 10
10680 Athens
Greece