BS EN 60308-2005 pdf download.Hydraulic turbines Testing of control systems.
— the unit is operating according to specification:
— the safety requirements are fulfilled;
— the specific contractual guarantees are fulfilled.
6 Control system tests
6.1 General
In order to keep the commissioning period as short as possible, it is recommended that the largest part possible of the required contractual tests be carried out in the manufacturer’s works (workshop tests). The on site tests should be limited to the demonstration of such characteristics, which:
— are indispensable for the safety, and
— which cannot be carried out without the generating unit and the pressure supply system. In the following subclauses, some basic aspects are summarised.
6.2 Recommendations on workshop tests
The scope of the tests, the best set up and the extent of the documentation should be stipulated in the contract in accordance with requirements. Thereby type tests, including EMC type tests with certificates shall be considered. It should be stipulated, who will witness the tests.
For workshop tests, it is not necessary to set up all components in a complete loop, the following subsystems (which may be different makers’ responsibility) can rather be tested separately:
— cabinet with plug-in units for control:
— servo-positioners, control valves with a test servomotor if necessary:
— oil pressure supply systems.
In this case, signals at interfaces between separately tested equipment shall be clearly defined and measurable.
It is appropriate to arrange for the simulation of simple circuits to test subsystems and/or to employ a plant simulator if available to test the complete control process for overall performance.
Individual testing of components and/or subsystems may not be needed in case the complete system is assembled.
For control systems, the following measures and steps apply.
— Safety devices, displays, alarms and trip settings should be verified prior to conducting field tests of control systems.
— Commissioning of the complete generating unit has to be performed including load rejection tests as per IEC 60041:1991 and the testing of control systems shall be coordinated with the commissioning of Hydro generating equipment. Refer to IEC 60545.
For the actual control system tests:
— The relevant mode to be checked is set, such as no-load, isolated network operation, frequency-power control or level control; subsequently defined test signals are superimposed and resulting changes for the specified values through the entire operating range are observed/recorded, whereby control settings can be optimised during the process. The results of such tests can be used as baseline values in order to be compared with the results of maintenance tests which are carried out during the life of the equipment.
— The insensitivity of the controller can be checked; this test is only needed when the power station will be participating in primary regulation of network frequency, especially in peak load power stations, also In power stations with a distinct requirement for high control accuracy (for recommended insensitivities. see 4.3.2 of IEC 61362. acceptable measuring uncertainties are given in Clause 7).
— Controller parameters can be determined. If the guaranteed behaviour is not achieved and the reason for this has to be identified, then other functions influencing the control system behaviour shall be examined. These functions may include: masses, generator-load characteristics and the influence of regulator forces on actuating times. In certain cases, the determination of the controller parameters and of the turbine transfer function may be used to provide models of the power plant, in order to carry out analytical studies of the dynamic behaviour of the power system.
— The turbine characteristics of pump turbines may need to be determined in detail in order to provide a basis for a reliable control strategy.
6.3.2 Existing control systems
6.3.2.1 IndIcation of control deficiencies
Deficiencies in existing control systems may have the following effects:
— long settling times of the controlled variable;
— long synchronisation times, excessive damping;
— drifting operating points;
— changes in actuator speeds;BS EN 60308-2005 pdf download.