Measurements of power and energy produced by the wind turbines in the Wind Farm were recorded in the corresponding SCADA showing a wide disparity for each technician. This project was developed as a prelude to the draft of the integrated management optimisation project at Sotavento Wind Farm (EFIVENTO) therefore it shares a similar initial problem:
- Measurement of power and energy in each turbine made at different points of the low voltage grid depending on the technician
- Unsynchronized measurement snapshots, each technician referencing it to its corresponding SCADA, which distorts the simultaneous production curve of the Wind Farm
- Storage formats different electrical variables in the various SCADAs
- Absence of generated power data at certain intervals by communication failure between wind turbine and its corresponding SCADA
The project sought the implementation of a permanent and centralized procurement of energy measurements, active-reactive power registered in the different wind turbines and Wind Farm substation.
The characteristics of this measurement process helped save the aforementioned drawbacks and consequently to pinpoint a number of essential tasks in the management of a wind farm to be able to determine:
- Actual energy flows at the wind farm
- Deviations of wind energy in respect to the meters themselves accounted for in each machine
- Simultaneity curve true to production for estimating prediction methods of wind production and testing of the effects of contrails between wind turbines
- Calculating availability and power curve from standardised measurements in all wind turbines, thus calculating it in the possible absence of data due to communication problems
The actions carried out in the project have been developed in two distinct stages:
- Installation of measuring and recording equipment
- Configuring Network Communications
Described below are the elements of each.
1. Measuring and recording equipment
This part consists of the current transformers and network analysers.
Intensity transformers (IT)
Element intensities measured charge or current generation of different turbines. They are situated before the connection to the transformer in the three phase so flow voltage cables; criterion for establishing uniform and comparative values.
It means that in the doubly-fed wind turbines (as in the case of Gamesa) you must register the rotor and stator powers generated, as they have doubled the current transformers in them. The current transformers have been installed in 24 wind turbines at the wind farm.
This is electronic equipment responsible for registering the measured electrical variables in the turbine, from the intensity registered alongside the current transformers.
The generated voltage measurements do not require the use of voltage transformers to allow these network analyzers directly onto the generation voltage of the wind turbines.
The electrical parameters measured are:
- Voltage -simple and compound
- Current per phase
- Active power in four quadrants
- Reactive power in four quadrants
- Power Factor
- Incremental active energy in one minute intervals
- Incremental reactive energy in one minute intervals
The equipment offers the possibility to display these values directly on display
Analysers are installed on the Circutor network on 24 turbines and on the output 132 kV transformer of the wind farm substation.
2. Communications network configuration
Local PCs on turbines and substation
25 computers have been installed for local storage of all relevant information received from network analyser, via RS-232 communication. Each computer is configured with communications manager software to perform the following tasks:
- Reading and displaying instantaneous measurements
- Storage of historical data
- Checking communications status
- Interconnection in real time with the central server, in order to integrate this information with other wind farm management programs
In addition, each PC is equipped with an uninterruptible power supply to protect against data loss or possible network failures
Integration of wind turbine and substation LAN
The next step was the full integration of PCs of the wind turbines from the wind farm and substation on a single LAN, a system pioneered in Europe. The integrated communications system used was Ethernet, via TCP-IP protocol, controlled through the central server located in the control building.
The advantages of this are meshed communications include:
- Greater stability
- Transmission rate of 100 Mbytes, much higher than point to point systems used in other wind farms.
Currently the project is in operation, recording in secondly and ten-minutely intervals the electric network parameters onto the database.