BS EN 62006-2011 pdf download.Hydraulic machines Acceptance tests of small hydroelectric installations.
A small hydroelectric turbine may be fitted with a speed governor for one or more of the reasons described below.
6.3.3.2 Synchronizing only
This mode is used when a small turbine is required to connect to a large grid. The speed governor may then be used to load the turbine, using speed droop, or may switch to another management system such as level control.
Once synchronized, the governor should automatically switch to the appropriate operational mode. The timing of the changeover is important if delay could cause a conflict between the grid frequency control and the turbine governor.
6.3.3.3 Frequency control on an isolated system
A small turbine may have difficulty In accepting the load changes on an isolated grid without large frequency fluctuations. The contract should state what size and type of load is expected and the frequency tolerance that is to be achieved. A grid supplied by a single hydroelectric unit shall be configured so that the plant can be started. The load should be segmented so that load increments are applied as agreed in the contract.
6.3.3.4 Frequency stability in conjunction with diesel generators
A small local grid may contain a mixture of turbines and other prime movers, such as diesel generators. The contract should state what role the small hydroelectric turbine is expected to provide, The ability of the turbine to provide frequency stability depends on its relative size compared to the other generators, and its speed of response. The governor shall be tested to verify that it can cope with the expected load changes within the frequency tolerance stated in the contract.
6.3.4 Unit operating with a voltage governor
A voltage governor is used when the generator takes part in controlling the reactive energy on the grid. The excitation of a synchronous generator is adjusted to maintain the voltage or power factor within prescribed limits. The voltage or power factor variation should be measured using a data logger during the load tests and load rejection tests. The ability of the voltage governor to maintain the voltage depends on the other generators feeding the grid. The acceptable limits shall be specified in the contract.
An asynchronous generator may have a controller to adjust the power factor of the unit. This is usually in the form of extra capacitors across the load.
6.3.5 Unit operating with a controller
6.3.5.1 Head level controller
The discharge through the turbine is controlled to maintain the head or tall water level. The discharge should be varied throughout its operational range to identify whether the controller can operate in a stable manner. It there are two or more hydroelectric units, or single units with multiple jets, connected to the same supply, there should be an overall water management system to start up or shut down the turbines in order to maintain the head level.
If operational guarantees have been specified in the contract, then measurements of the variation of head level should be made.
6.3.5.2 Unit operating with a load management controller
The load management controller maintains power output from the generator at the present level. The controller should operate in a stable manner throughout the permissible operating range. Variations of voltage and head that affect the control and the allowable limits of variation of power shall be agreed contractually.
If operational guarantees have been specified in the contract, the measurement of the load deviation from the set point should be made.
6.3.5.3 Unit operating with an electric load governor
The electric load governor Is used on an isolated system so that the generator produces a constant power output. Excess power is switched to and from a resistor to match the load changes on the system. The resistance has to dissipate the excess power as heat and shall be able to operate within the temperature limits defined by the manufacturer. The operational temperature of the governor should therefore be monitored during load tests and load rejection tests.
The load governor can cause electrical emissions of radio frequency interference when switching loads. BS EN 62006-2011 pdf download.