GB/T 31066-2026Electro-technical terminology - Control system for hydraulic turbines (English PDF)

Foreword

This document was drafted in accordance with the rules given in GB/T 1.1-2020, Directives for standardization—Part 1: Rules for the structure and drafting of standardizing documents.

This document replaces GB/T 31066-2014, Electro-technical terminology—Control system for hydraulic turbines. Compared with GB/T 31066-2014, and apart from structural adjustments and editorial changes, the main technical changes are set out in the document as a list of the definitions that have been revised, the English equivalents that have been corrected, the terms that have been renamed, and the terms and definitions that have been added.

Attention is drawn to the possibility that some of the content of this document may be the subject of patent rights. The issuing body of this document bears no responsibility for identifying patent rights.

This document was proposed by the China Electrical Equipment Industry Association. It is under the jurisdiction of the National Technical Committee on Hydraulic Turbines of Standardization Administration of China (SAC/TC 175).

The previous editions of this document and of the document it replaces are as follows: first published in 2014 as GB/T 31066-2014; this is the first revision.

1 Scope

This document defines the terms specific to hydraulic turbine control systems.

This document applies to the drafting of standardizing documents in the field of hydraulic turbine control and to the preparation of technical documents and of tender and bid documents; it is used for reference in the writing and translation of specialist literature, teaching material, books and periodicals.

2 Normative references

There are no normative references in this document.

3 Types of equipment

3.1 governor; speed governor: General term for the one or several devices, made up of the mechanisms and indicating instruments, that carry out the regulation of a hydraulic turbine and the corresponding control.

3.2 mechanical hydraulic governor: Governor in which the speed measuring, damping and feedback signals are produced by mechanical means and combined by mechanical means, and in which the turbine servomotor is driven through a hydraulic amplification stage.

3.3 electric-hydraulic governor: Governor in which the detection of the controlled variable and the damping and feedback signals are produced by electrical means and are combined and amplified by electrical circuits, and in which the turbine servomotor is driven through an electro-hydraulic conversion and a hydraulic amplification stage.

3.4 microcomputer based governor: Electro-hydraulic governor that uses a microcomputer controller as the platform on which signals are measured, converted and transmitted and the control law is combined.

3.5 dual regulating governor: Governor that carries out the dual regulation of the guide vanes and the runner blades of a Kaplan turbine, of the needles and the deflectors (cut-in deflectors) of an impulse turbine, and of the guide vanes and the pressure regulating valve of a turbine fitted with a pressure regulating (relief) valve. [SOURCE: DL/T 563-2016, 3.6, modified]

3.6 governor without pressure vessel; through flow type governor: Governor with no pressure tank or accumulator, in which the oil pump (hydraulic pump) supplies oil directly to the turbine governing system.

3.7 governor with pressure tank: Governor in which oil is supplied to the turbine governing system by a pressure tank (a non-separated accumulator).

3.8 governor with accumulator: Governor in which oil is supplied to the turbine governing system by a hydraulically separated accumulator.

3.9 governor for pump-turbine: Governor used for the control of a pump-turbine.

3.10 governor for variable speed turbine/pump-turbine: Governor used for the control of a variable speed turbine or of a variable speed pump-turbine.

3.11 position operator; gate operator: Operating/control device that exerts no automatic regulating action on the unit and is able only to start and stop the unit, to bring it to a predetermined load once it has been connected to the grid, and to stop it automatically on receipt of an emergency signal.

3.12 electronic load controller: Electronic regulating device, built from electronic circuits, that controls the speed of the unit by balancing the load.

3.13 governor with electric motor driving opening operator: Governor that controls the opening of the turbine by means of an electric motor acting through a reduction gear or a ball screw.

3.14 oil pressure (supply) unit: Unit made up of a pressure tank/accumulator, a return oil tank, a motor, oil pumps, control valves, oil filters, connecting pipework and the associated ancillary components, which supplies hydraulic power to the control equipment of hydroelectric generating units and to the operating equipment of hydraulic steel structures.

4 Control system

4.1 hydraulic turbine governor (control) system: System made up of the items of equipment that detect the deviation between the controlled variables (speed, power, water level, flow, and so on) and the set (target) variables and convert that deviation, according to a given characteristic, into a travel of the main servomotor. NOTE: That is, the combination of the control equipment and components belonging to the hydraulic turbine governing system, including the control cubicle/governing cubicle, the oil pressure unit, the servo-system and the main servomotor.

4.2 controlled system/process: System controlled by the hydraulic turbine governor system. NOTE: It includes the turbine/pump-turbine, the water conveyance and discharge system, the generator/generator-motor together with its voltage regulator, and the grid into which the machine is connected.

4.3 hydraulic turbine governing/regulating system: Closed-loop regulating system made up of the hydraulic turbine governor system and the controlled system.

4.4 droop control: Regulating mode in which the hydraulic turbine governor system is in the automatic regulating state and the permanent speed droop is not zero.

4.5 isochronous control: Regulating mode in which the hydraulic turbine governor system is in the automatic regulating state and the permanent speed droop is equal to zero.

4.6 servo-system; servo-positioner: Displacement feedback control system/device that automatically follows the output of the controller (regulator) and carries out signal conversion and power amplification.

5 Control functions

5.1 frequency [speed] control: Control mode in which the regulating system takes the frequency [speed] of the unit as the target of regulation.

5.2 power control: Autonomous closed-loop control mode in which the regulating system takes the active power of the unit as the target of regulation.

5.3 opening control: Control mode in which the regulating system takes the opening as the target of regulation.

5.4 level control: Control mode in which the regulating system takes the water level as the target of regulation.

5.5 flow control: Control mode in which the regulating system takes the flow as the target of regulation.

5.6 surge control: Control mode in which, in a low head turbine, a specific control is applied to the guide vanes and the runner blades of the turbine in order to limit the surge of the river.

5.7 primary frequency control/regulation; PFC/PFR: Control function by which, while the unit is running connected to the grid and the frequency of the local grid departs beyond the frequency (speed) dead band, the regulating system autonomously changes the active power of the unit or the opening of the guide vanes/needles (or the opening of the runner blades and of the deflectors), according to the droop or the permanent speed droop coefficient that has been set, so as to stop the frequency departing further from its rated value. NOTE: The primary frequency control function appears only in the opening regulating mode or in the power regulating mode, its target of regulation being the opening or the active power of the unit. In that situation the capacity of this unit is a small share of the current regulating capacity of the grid, the grid has a certain stability margin, and the change in the power of a single unit has only a limited effect on the grid, not enough to bring about frequency-power hunting and instability. Unlike AGC, it is an adjustment made to load changes of short period (below the minute scale), and what it responds to is the instantaneous deviation of the local frequency of the unit, whereas what AGC responds to is generally a remote power target command from the dispatching centre. [SOURCE: DL/T 563-2016, 3.29, modified]

5.8 collaborative (coordination) control for variable speed turbine/pump-turbine: Control in which the various target commands are issued by a collaborative controller and the governor, the converter and the other equipment act together to achieve the coordinated control of power, head, speed and opening in generating mode, and the coordinated control of input power, delivery head, speed and opening in pumping mode.

5.9 speed-power control mode for variable speed turbine/pump-turbine: Control mode in which a variable speed turbine or variable speed pump-turbine is in generating mode, the converter takes the speed of the unit as its control target and the governor takes the active power output of the unit as its control target.

5.10 power-speed control mode for variable speed turbine/pump-turbine: Control mode in which a variable speed turbine or variable speed pump-turbine is in generating mode, the converter takes the power output of the unit as its control target and the governor takes the speed of the unit as its control target.

5.11 power-opening control mode for variable speed pump-turbine: Control mode in which a variable speed pump-turbine is in pumping mode, the converter takes the input power of the generator-motor as its control target and the governor takes the opening as its control target.

5.12 speed-opening control mode for variable speed pump-turbine: Control mode in which a variable speed pump-turbine is in pumping mode, the converter takes the speed of the unit as its control target and the governor takes the opening as its control target.

6 System structure types

6.1 proportional-integral governor; PI governor: Governor that carries out the proportional-integral control law.

6.2 proportional-integral-derivative governor; PID governor: Governor that carries out the proportional-integral-derivative control law. NOTE: Ideal PI and PID regulation with constant parameters was born in an age when the computing resources of control systems were extremely precious; today the computing resources of the controller of a microcomputer governor are no longer the bottleneck in the choice and the design of the control strategy or in the combining of the control law. Even so, PID will go on being used in the industry for a long time. It should be pointed out that, where the control requirements are complex, control strategies such as PID with parameters varying over the whole operating range, higher-order control algorithms (for example state feedback control), model predictive control (MPC), intelligent control (IC) and optimal control (OC) may be better suited to some applications.

6.3 series PID governor: Governor that carries out the PID control law with a structure of elements in series.

6.4 parallel PID governor: Governor that carries out the PID control law with a structure of elements in parallel.

6.5 damping type governor: Governor whose feedback path contains a damping device. NOTE: Its control law is equivalent to series PI regulation.

6.6 acceleration-damping type governor: Damping type governor whose frequency (speed) measuring unit contains an acceleration element. NOTE: Its control law is equivalent to series PID regulation.

7 Structure and components

7.1 Speed/frequency measuring components

7.1.1 speed measuring device/unit: Device that detects the speed or the speed deviation of the unit and converts it into the corresponding output quantity.

7.1.2 (centrifugal) pendulum: Component that detects the speed deviation of the unit by the rotation of mechanical parts and converts it into the corresponding displacement output of a mechanical member.

7.1.3 frequency measuring unit: Unit that detects the frequency by analogue or digital means and converts it into the corresponding output quantity.

7.2 speed signal source: Device that produces and provides a frequency/speed signal source. NOTE: Common speed signal sources include permanent magnet generators, the voltage transformers of the generating unit, toothed-wheel speed measuring devices and very low frequency signal generators.

7.3 artificial dead band module/unit: Unit that, in the automatic operating state, deliberately prevents the control system from exerting any regulating action within a specified range of the controlled variable.

7.4 Electrical-hydraulic and electrical-mechanical converting components

7.4.1 electro-hydraulic converter: Component that converts an electrical input signal, through hydraulic amplification, into a flow and pressure output of the corresponding direction, or into the corresponding mechanical displacement output. NOTE: It includes displacement type electro-hydraulic converters, servo valves, proportional valves, proportional servo valves, high-speed switching valves and solenoid directional valves.

7.4.2 electro-mechanical converter: Component that converts an electrical regulating signal into a mechanical displacement output.

7.5 Directional-flow control valves

7.5.1 distributing valve: Hydraulic control (regulating) valve in which the direction and the flow rate of the fluid delivered change with the direction and the amount of travel of the spool [the distributing valve piston]. NOTE: Also called a directional-flow control valve.

7.5.2 pilot distributing valve: Distributing valve that controls the movement of the auxiliary servomotor or of the pilot servomotor.

7.5.3 main distributing valve; control valve: Distributing valve that controls the movement of the servomotor of the guide vanes [needles], of the runner blades [deflectors/cut-in deflectors] or of the pressure regulating valve.

7.6 Damping components

7.6.1 damping device: Feedback correcting device/component whose input signal is the displacement of the servomotor, whose output signal is related to the rate of change of the input signal, and which is compared with the speed deviation signal.

7.6.2 (mechanical hydraulic) dashpot: Mechanical part/component that performs the function of the damping device in a mechanical hydraulic governor.

7.6.3 electrical damper module: Electrical unit or program module that performs the function of the damping device.

7.7 Opening limiting devices

7.7.1 mechanical opening limiter: Mechanism that limits the opening of the guide vanes or of the needles by mechanical means.

7.7.2 electrical opening limiter: Electrical unit or program module that limits the opening of the guide vanes or the opening of the needles.

7.8 Speed [power] adjusting devices

7.8.1 speed adjusting mechanism; speed changer: Mechanism in a mechanical hydraulic governor used to change the speed of the unit when the unit is running isolated, and to change the power output of the unit when the unit is running connected in parallel with the grid.

7.8.2 power setting module: Electrical unit or program module that sets and changes the target value of the power regulation of the unit.

7.8.3 frequency setting module: Electrical unit or program module that sets and changes the target value of the frequency [speed] regulation of the unit.

7.9 Servo actuators and types of control

7.9.1 servomotor: Device (actuator) that converts the hydraulic energy of a fluid into mechanical force and linear movement and drives the movement of an operating mechanism (or control component).

7.9.2 auxiliary servomotor: Servomotor that controls the main distributing valve. NOTE: When the hydraulic turbine governor system is in the steady state, its piston always stays in the position corresponding to the neutral position of the main distributing valve.

7.9.3 pilot servomotor: Servomotor that controls the pilot distributing valve or the main distributing valve. NOTE: When the hydraulic turbine governor system is in the steady state, its piston may stop in any position that complies with the design.

7.9.4 Main servomotors

7.9.4.1 guide vane [needle] servomotor: Servomotor that is controlled by the main distributing valve/control valve and drives the guide vanes [the needles].

7.9.4.2 (runner) blade [deflector/cut-in deflector/pressure regulating (relief) valve] servomotor: Servomotor that is controlled by the main distributing valve/control valve and drives the runner blades [the deflector/the cut-in deflector/the pressure regulating valve].

7.9.5 asynchronous guide vane: Part of the guide vanes that can be operated under separate control and can also take part in the linked regulation of the control ring. [SOURCE: GB/T 36550-2018, 4.2.11, modified]

7.9.6 single guide vane control: Control in which every guide vane is controlled by its own independent servomotor. [SOURCE: GB/T 36550-2018, 4.2.10, modified]

7.10 combination (on-cam) device: Mechanism, electrical unit or program module in the hydraulic turbine governor system that establishes the combination relationship between the runner blades and the guide vanes, or between the deflectors and the needles, at the different operating heads and unit powers.

7.11 summation and amplification module: Unit that combines, processes and amplifies several electrical signals and control variables.

7.12 displacement converting component: Converting component that converts the displacement signal of the servomotor [of the distributing valve] into the corresponding electrical [mechanical] signal.

7.13 step closing device: Device that changes the closing rate of the main servomotor from a predetermined position of that servomotor onwards.

7.14 Pressure vessels

7.14.1 pressure tank: Pressure vessel in which the oil and the gas are not separated. NOTE: That is, a pressure tank body of the non-separated type.

7.14.2 accumulator: Pressure vessel in which a separating member is placed between the gas and the oil so that the gas does not mix into the oil.

7.15 sump tank: Tank in the oil pressure unit that collects the oil that is not under pressure.

7.16 unloading valve: Control valve that discharges the oil delivered by the oil pump to the sump tank, so unloading the pump set, when the pump starts or when the pressure in the pressure tank reaches the upper limit of the normal working oil pressure.

7.17 safety valve: Control valve that opens when the pressure exceeds the specified value and relieves the pressure, so protecting the safety of the hydraulic system.

7.18 combination valve; group valve: Valve assembly that brings the unloading valve, the safety valve and the check valve (non-return valve) together into one item.

7.19 air safety valve: Pressure control valve that opens when the air pressure inside the pressure tank exceeds the specified value and relieves the pressure, so preventing the pressure inside the pressure vessel from exceeding the specified figure.

7.20 pressure tank air replenishment device: Device that receives an external control signal and adds compressed air to the pressure tank in order to maintain a suitable ratio of air to oil in the tank.

7.21 control cubicle of oil pressure (supply) unit: Control cubicle that controls the pump-motor sets, the solenoid valves and the other associated ancillary components of the oil pressure unit.

7.22 oil leakage collection device: Device that collects and automatically returns leakage oil. NOTE: It generally consists of a leakage oil tank, a leakage oil pump, a check valve, an oil level gauge and other associated fittings.

7.23 overspeed limiter: Switching device made up of (or integrating) an emergency distributing valve, a solenoid directional valve, a travel-operated directional valve and the associated oil circuit control valves, used to switch the oil circuits quickly when the speed of the unit exceeds a set value and the governor has failed, by shutting off the oil circuit coming from the main distributing valve of the governor, connecting the closing chamber of the servomotor directly to the pressure oil and connecting the opening chamber of the servomotor to the return oil. [SOURCE: GB/T 11805-2019, 3.8, modified]

7.24 pressure regulating valve; pressure relief valve; PRV: Regulating valve that is able to open quickly at the same time as the guide apparatus of the turbine closes quickly, and to discharge part of the flow, so limiting the water hammer pressure in the penstock and in the spiral case. NOTE: It is sometimes also called a free discharge valve, a relief valve or a pressure release valve. [SOURCE: DL/T 563-2016, 3.41, modified]

8 Operation and testing

8.1 Operating methods

8.1.1 automatic operation: Operating method in which the turbine is regulated automatically by the hydraulic turbine governor system from the controlled variable and/or the set signal (target quantity).

8.1.2 Manual operation

8.1.2.1 manual operation: Operating method in which the turbine is controlled by hand through the relevant parts/components.

8.1.2.2 electrical manual operation: Manual operation carried out by electrical control means.

8.1.2.3 mechanical manual operation: Manual operation carried out by mechanical hydraulic control means.

8.2 Operating states

8.2.1 idling operation: Operating method in which the unit is not connected to the grid and runs at the rated speed in the turbine direction with the excitation system not in service.

8.2.2 no-load operation: Operating method in which the unit is not connected to the grid and runs at the rated speed in the turbine direction with the excitation system in service.

8.2.3 load limit operation: Operating method in which the hydraulic turbine governing system is running automatically and the power output of the unit is limited.

8.2.4 load operation: State in which the unit is connected to the grid and carries load, running at the specified speed and the specified voltage.

8.2.5 load rejection: Transient process in which the unit suddenly throws off the load it is carrying.

8.2.6 isolated grid operation: Operating method in which, within a local grid that has no electrical connection to the main grid, there is only one unit, or the capacity of this unit is a large share of the current regulating capacity of that grid, and this unit acts as the main regulating source. NOTE 1: In that situation the operating control mode of the hydraulic turbine governing system is usually the frequency regulating mode. NOTE 2: This document delimits the interconnected grid and isolated grid operating states of the hydraulic turbine governing system from the point of view of the capacity of the unit relative to the current regulating capacity of the grid, and not purely by the size of the grid and the features of its network structure. For example, in a weak, independently operating grid of 100 MW capacity, if the capacity of a single connected unit is 10 MW, the hydraulic turbine governing system is to be treated as being in the isolated grid operating state and its control mode is the frequency regulating mode, for which a control structure and control parameters different from those used in interconnected grid operation are needed if forced frequency-power oscillation and grid collapse are to be avoided; if in that same weak grid a unit of only 0.3 MW is connected and running, its hydraulic turbine governing system can be treated as being in the interconnected grid operating state, since from the point of view of the share of capacity that weak grid is, for that unit, equivalent to a large grid, and it is then to run in the opening regulating mode or in the power regulating mode, with no need to run in the frequency regulating mode.

8.2.7 island (small or medium scale grid) operation: Operating method in which this unit runs interconnected with a relatively small number of other units in a grid of small or medium capacity. NOTE: In a direct current transmission environment, when a local grid of small or medium capacity has been disconnected from all the alternating current tie lines to the main grid and is connected to the main grid only through the direct current link, this is usually called island operation or island-area operation. Depending on the actual operating needs of the grid and on the share of the capacity of the single unit, the operating control mode of the hydraulic turbine governing system may then be the opening regulating mode or the power regulating mode, and may also be the frequency regulating mode.

8.2.8 interconnected grid operation; large interconnected power system operation: Operating method in which the unit is connected into an interconnected grid of large capacity. NOTE 1: In that situation this unit has little effect on the grid and the operating control mode of the hydraulic turbine governing system is usually the power regulating mode or the opening regulating mode, and sometimes the water level regulating mode or the flow regulating mode. NOTE 2: In interconnected grid operation the power change of a single unit, including a sudden load rejection, is not enough to bring about a large frequency disturbance or frequency instability in the grid.

8.2.9 stop mode; ST: State in which the unit is at rest and shut down. [SOURCE: GB/T 36550-2018, 8.3]

8.2.10 generator mode; G: Operating state in which the unit converts the energy of the water into electrical energy.

8.2.11 generator condenser mode; GC: State in which the runner turns in air and the unit is connected to the grid running in the generating direction.

8.2.12 pump mode; P: Operating state in which the unit converts electrical energy into the potential energy of the water.

8.2.13 pump condenser mode; PC: State in which the runner turns in air and the unit is connected to the grid running in the pumping direction.

8.2.14 back to back startup; BTB: Method in which one unit is started in the generating direction and, through the starting circuit, drives another unit started in the pumping direction.

8.2.15 launcher mode; L: Operating condition in which the units are started back to back, the driving machine runs in the generating direction and takes the driven machine from rest up to rated speed, after which the driven machine is connected to the grid.

8.2.16 class B black start mode; BS: Process in which a hydroelectric power station, with no alternating current station service supply available, uses the electrical energy stored in the batteries of the station direct current system and the hydraulic energy stored in the pressure tank/accumulator of the oil pressure unit to start the unit and restore the station service supply, and works with the grid dispatcher to restore the operation of the grid.

8.2.17 mode transition; operating condition switch-over: Control process in which the governor changes the operating condition of the unit according to the control commands and the operating conditions.

8.2.18 steady state: Operating state in which the unit runs at constant load, constant set (target) signal and constant head, and all the variables of the hydraulic turbine governing system are in balance.

8.2.19 small disturbance/transient/oscillation process: Dynamic process in which the hydraulic turbine governing system undergoes a relatively small change of the controlled variable, the output quantity of none of the control elements/components reaches its limit (saturation), and the variables concerned change essentially in a linear manner.

8.2.20 large disturbance/transient/oscillation process: Dynamic process in which the hydraulic turbine governing system undergoes a relatively large change of the controlled variable, the output quantity of at least one control element/component reaches saturation, and the variables concerned change essentially in a non-linear manner.

8.3 Verification tests

8.3.1 type test: Test carried out at the stage at which the design of a new product is settled, in order to verify whether the functions and the performance of the product can meet all the requirements of the technical specification.

8.3.2 acceptance test: Test carried out with the participation of both the user (or the body appointed by the user) and the equipment supplier, in order to verify that the product complies with the quality requirements and the guaranteed items laid down in the contract and in the relevant standards.

8.3.3 factory acceptance test; FAT: Test carried out on the product when it leaves the works, in accordance with the provisions of the contract and the relevant standards.

8.3.4 site acceptance test; SAT: Test carried out, in accordance with the provisions of the contract or the relevant standards, on a product already installed on site at the power station.

8.4 Dynamic tests

8.4.1 no-load disturbance test: Test in which, with the unit running at no load, each of the regulating parameters is changed in turn and a frequency disturbance is applied to the hydraulic turbine governor system, and the no-load regulating parameters of the hydraulic turbine governor system are chosen on the basis of the dynamic quality of the hydraulic turbine governing system.

8.4.2 load test: Test that checks the regulating performance of the governing system when running at the various loads and when the load changes suddenly, and by which the regulating parameters of the hydraulic turbine governor system for operation on load are selected.

8.4.3 load rejection test under turbine mode: Test in which the load carried is thrown off while the unit is running steadily in generation, in order to check the dynamic regulating process of the governing system, to verify the closing time and the closing law of the servomotor, and to examine the change of water pressure and of speed and the changes in the vibration and the shaft run-out at the various parts of the unit.

8.4.4 input rejection test under pump mode: Test in which the pumping power supply is lost while the unit is running steadily in pumping, in order to check the shut-down control process of the governing system, to verify the closing time and the closing law of the servomotor, and to examine the change of water pressure and of speed and the changes in the vibration and the shaft run-out at the various parts of the unit.

8.4.5 test for switchover from pump mode to generator mode: Mode transition test in which the unit changes from the pumping state to the generating state.

8.4.6 black start test: Test in which, after the station service supply and the supply from the external grid have been lost, the emergency supply available at the station, the electrical energy stored in the direct current batteries and the hydraulic energy stored in the hydraulic system are used to start the unit, generate, and restore the supply to the line.