Iec 60308 2005

INTERNATIONALE IECINTERNATIONAL STANDARD 60308 Deuxième éditionSecond edition2005-01 Essais des systèmes de régulation Hydraulic turbines – Testing of control systems Numéro de référe

Systèmes de régulation proprement dits

Les modes primaires sont les suivants:

(fonctionnement à vide et synchronisation, fonctionnement en réseau isolé)

Les modes secondaires sont les suivants:

– régulation de niveau ou de positionnement CEI 61362 3.1.3

Autres systèmes de commande et transitions

Les autres systèmes de commande et transitions sont les suivants:

– régulation de pression CEI 61362 4.15.1 et 4.15.3

– transitions entre les différents modes de commande

Composants des systèmes de régulation

Les composants des systèmes de régulation sont les suivants:

– convertisseurs électro-hydrauliques et électromécaniques

– systèmes d’alimentation en huile sous pression CEI 61362 4.11 et équipements de stockage d’énergie

– alimentation en puissance auxiliaire pour les systèmes électriques/électroniques

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

4 Functions and components of hydro control systems

In this clause, the functions and components are listed, which may be subjected to tests and verifications

NOTE Again reference is made to IEC 61362 for explanation and definition

The primary modes are the following:

– speed control (no-load and synchronising, IEC 61362 3.1.1 isolated operation)

The secondary modes are the following:

– water level control or positioning IEC 61362 3.1.3

– optimisation control (station control) IEC 61362 4.9

4.2 Other control systems and transitions

The other control systems and transitions are the following:

– start up and synchronisation IEC 61362 4.13.1

– shutdowns and load rejections IEC 61362 4.13.2

– transitions between different control modes

The control system components are the following:

– electro-hydraulic and electro-mechanical converters

– pressure oil supply systems and IEC 61362 4.11 energy storage mechanisms

– auxiliary power supply for electrical/electronical systems

Fonctions de sécurité, 4.14 de la CEI 61362

Les fonctions de sécurité sont les suivantes:

Protection vis-à-vis de l’environnement, 4.16 de la CEI 61362

Pour les systèmes de régulation, les aspects suivants sont à prendre en compte:

Compatibilité électromagnétique (CEM)

Pour les systèmes de régulation, les aspects suivants sont à prendre en compte:

Garanties et essais de réception

In the verification process of guarantees established according to IEC 61362, it is recommended to apply these standards to both new and existing control systems for power plants.

– déterminer les caractéristiques du système réglé;

– déterminer l’étendue des essais des régulateurs pour vérifier les garanties, ainsi que l’étendue de la documentation (voir 5.2);

– stipuler les mesures à prendre en cas d’insuccès vis-à-vis de la satisfaction des garanties

In the process of verifying the actual status of an existing regulator, only measurements that assess the most important basic properties will be conducted, such as its operation in an isolated network.

A test leader will be appointed to oversee the testing procedure, including the recording and documentation of results The scope and format of the documentation must be agreed upon in advance.

Documentation

Pour chaque essai, les informations suivantes doivent être documentées:

The safety functions are the following:

For control systems, the following aspects are relevant:

When verifying guarantees established per IEC 61362, it is advisable to apply the recommendations for both new control systems in new plants and for existing power plants.

– establish the characteristics of the controlled system;

– establish scope of control system tests to verify guarantees and scope of documentation

– stipulate measures to be taken in the event of failure to comply with guarantees

To verify the current status of an existing control system, it is essential to conduct measurements that assess key fundamental properties, such as the operation of an isolated network.

A test manager will oversee the testing process, ensuring proper recording and documentation of results, with the scope and format of the documentation established in advance.

For every test, the following shall be documented:

Proper documentation is crucial, especially when certain tests need to be repeated at specified intervals, such as for regulatory authorities, insurance companies, or during restarts after maintenance It is essential to take precautions to mitigate environmental risks.

Les valeurs mesurées peuvent être enregistrées et traitées, soit

– en utilisant des instruments d’enregistrement adaptés avec évaluation manuelle ultérieure, soit

– en ligne à l'aide d'un ordinateur raccordé directement avec résultats imprimés faisant partie intégrante de la documentation

Dans le cas des mises en service, il convient qu’un rapport final démontre que

– le groupe fonctionne conformément à la spécification;

– les exigences de sécurité sont satisfaites;

– les garanties spécifiques contractuelles sont respectées

6 Essais du système de régulation

Généralités

To minimize the commissioning period, it is advisable to conduct the majority of required contractual tests at the manufacturer's facilities (factory testing) On-site tests should be limited to demonstrating the characteristics.

– qui sont indispensables à la sécurité, et

– qui ne peuvent être pratiquées sans le groupe générateur et le système d’alimentation en pression

Dans les paragraphes qui suivent, certains aspects de base sont résumés.

Recommandations sur les essais en usine

The contract should clearly outline the scope of testing, optimal organization, and documentation requirements in accordance with the specifications Consequently, type tests, including electromagnetic compatibility (EMC) tests with certificates, must be taken into account It should also specify who will attend the tests.

For factory testing, it is not necessary to install all components on a complete loop; instead, individual subsystems can be tested separately, which may be the responsibility of different suppliers.

– le coffret régulateur avec ses borniers;

– les servo-positionneurs, les soupapes de régulation avec un servomoteur d’essai si nécessaire;

– les systèmes d’alimentation en huile sous pression

Dans ce cas, les signaux aux interfaces entre les équipements testés séparément doivent être clairement définis et mesurables

It is advisable to simulate simple circuits to test subsystems and/or use an available installation simulator to evaluate the entire regulation process, thereby assessing overall performance.

L’essai individuel de composants et/ou sous-systèmes peut ne pas être nécessaire dans le cas ó le système complet est monté

Thorough documentation is essential for tests that need to be repeated at specific intervals, such as those required by authorities, insurance companies, or after revisions It is crucial to take precautions to prevent environmental hazards.

The measured values can be recorded and processed either:

– by using suitable recording instruments with subsequent manual evaluation, or

– on line by a directly connected computer with the printouts forming an integral part of the documentation

In the case of initial start-ups, a final report should demonstrate that

– the unit is operating according to specification;

– the safety requirements are fulfilled;

– the specific contractual guarantees are fulfilled

To minimize the commissioning period, it is advisable to conduct the majority of necessary contractual tests at the manufacturer's facility (workshop tests) On-site tests should be restricted to demonstrating specific characteristics.

– 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

The contract must clearly define the scope of tests, optimal setup, and documentation requirements This includes specifying type tests, such as EMC type tests with certificates Additionally, it should outline who will be responsible for witnessing 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;

In this case, signals at interfaces between separately tested equipment shall be clearly defined and measurable

To ensure optimal performance, it is advisable to simulate simple circuits for subsystem testing and utilize a plant simulator, if accessible, to evaluate the entire control process.

Individual testing of components and/or subsystems may not be needed in case the complete system is assembled

Recommandations sur les essais sur site

Pour les systèmes de régulation, les mesures et dispositions suivantes s’appliquent

– Il convient que les dispositifs de sécurité, d’affichage, d’alarme et d’arrêt soient vérifiés préalablement à la conduite des essais sur site des systèmes de régulation

The commissioning of the complete generator set must be carried out, including discharge tests in accordance with IEC 60041:1991 Additionally, the regulation system tests should be coordinated with the commissioning of the turbine and associated equipment, as referenced in IEC 60545.

Pour les essais du système de régulation proprement dit:

The appropriate operating mode to verify includes conditions such as no-load operation, isolated network functioning, frequency-power regulation, or level regulation Defined test signals are superimposed, and the resulting variations in specified parameters are observed and recorded across the entire operating range This process allows for the optimization of regulator settings during the test The results from these tests can serve as baseline comparison values for maintenance test results conducted throughout the equipment's lifespan.

The insensitivity of the regulator can be verified; this test is only necessary when the hydroelectric power plant participates in the primary frequency regulation of the grid, particularly for peak power plants and those with specific high precision regulation requirements For recommended insensitivities, refer to section 4.3.2 of IEC 61362, while acceptable measurement uncertainties are outlined in Article 7.

The parameters of the regulator can be determined, and if the guaranteed behavior is not achieved, it is essential to identify the underlying reasons Factors influencing the regulation system's behavior, such as inertia, characteristics of the alternator and load, and the impact of the regulator's efforts on maneuvering times, should be examined In some cases, determining the regulator's parameters and the turbine's transfer function can be utilized to create models of the hydroelectric power plant, enabling analytical studies on the dynamic behavior of the electrical system.

– Pour les turbines-pompes, il peut être nécessaire de déterminer, dans le détail, leurs caractéristiques en turbine afin de fournir une base pour une stratégie fiable de régulation

6.3.2.1 Implication des imperfections des régulateurs

Les imperfections dans les régulateurs existants peuvent avoir les effets suivants:

– temps d’ajustement des variables réglées trop longs;

– temps de synchronisation trop longs, amortissement excessif;

– dérive de points de fonctionnement;

– modifications des vitesses de manoeuvre;

– oscillations anormales (à vide et/ou en fonctionnement en réseau isolé, etc.);

– insensibilités excessives et/ou effets d’hystérésis;

– fuites excessives (période de pompage, température d’huile, etc.)

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

The complete commissioning of the generating unit must include load rejection tests in accordance with IEC 60041:1991, and the testing of control systems should be coordinated with the commissioning of hydro generating equipment, as outlined in IEC 60545.

For the actual control system tests:

To ensure optimal performance, the relevant operational mode—such as no-load, isolated network operation, frequency-power control, or level control—must be established Defined test signals are then superimposed, allowing for the observation and recording of changes across the entire operating range This process enables the optimization of control settings The outcomes of these tests serve as baseline values for comparison with maintenance test results conducted throughout the equipment's lifespan.

The insensitivity of the controller should be assessed when a power station is involved in primary frequency regulation, particularly in peak load scenarios or when high control accuracy is essential For recommended insensitivity levels, refer to section 4.3.2 of IEC 61362, which also outlines acceptable measurement uncertainties in Clause 7.

Controller parameters can be established, but if the desired performance is not met, it is essential to investigate other factors affecting the control system's behavior These factors may include masses, generator-load characteristics, and the impact of regulator forces on actuation times In some instances, determining the controller parameters and the turbine transfer function can help create models of the power plant, facilitating analytical studies of the power system's dynamic behavior.

– The turbine characteristics of pump turbines may need to be determined in detail in order to provide a basis for a reliable control strategy

Deficiencies in existing control systems may have the following effects:

– long settling times of the controlled variable;

– long synchronisation times, excessive damping;

– unusual oscillations (in no-load and/or isolated operation, etc.);

– excessive insensitivities and/or hysteresis effects;

– excessive leakages (pumping period, oil temperature, etc.)

Les contrôles suivants peuvent être faits:

– enregistrement des réponses à des échelons/fonctions de transfert (réponses à des échelons unitaires) en appliquant des signaux définis à l’entrée (signal de commande, grandeur réglée, fréquence, etc.);

– caractérisation en pression des servomoteurs;

– vérification de la relation de conjugaison pales/distributeur de turbines Kaplan;

– vérification de la relation de conjugaison déflecteur/aiguilles de turbines Pelton;

– mesures pour vérifier les paramètres de la centrale;

– vérification de la sécurité d’ensemble des conduits hydrauliques et de la tuyauterie

6.3.2.3 Décision entre le remplacement ou la réparation de régulateurs existants

The checks mentioned above will almost always provide insights into the reasons behind imperfections, enabling informed decisions on the necessary actions to take.

– vérification du fonctionnement fiable des équipements existants pour conservation;

– remplacement des composants ou des régulateurs complets;

– risques et conséquences de fuites d’huile

Outre les points mentionnés ci-dessus, les faits suivants peuvent également influencer la décision de remplacer ou de réparer des éléments ou des systèmes existants:

– l’évaluation des cỏts de fonctionnement;

– l’évaluation des cỏts de réparation;

– le potentiel d'amélioration du fonctionnement et du rendement induit par le remplacement face à la réparation;

– les exigences de sécurité générale ou autres exigences des autorités.

Vérifications électriques

The mechanical turbine regulator consists of electrical components such as control valves, servomotors, pumps, and pendulums (ball regulators), while the electronic regulator performs all regulatory functions, including pilot control.

Les systèmes électroniques sont sensibles aux interférences électromagnétiques Pour cette raison, il doit être porté une attention particulière aux points suivants:

– qualité de l’alimentation en énergie électrique;

– dispositions de filtrage et de blindage;

– insensibilité des composants vis-à-vis des interférences

The following checks can be made:

– recording of step responses/transient functions (unit step responses) by applying defined signals at the input (command signal, controlled variable, frequency, etc.);

– checking the runner/guide vane relationship in Kaplan turbines;

– checking the deflector/nozzle relationship in Pelton turbines;

– identifying possible resonances (draft tube, generator etc.);

– measurements to check the plant parameters;

– checking of the overall safety of the hydraulic conduit and the pipe-installation

6.3.2.3 Deciding whether to replace or to repair existing control systems

The checks outlined above typically reveal the underlying reasons for deficiencies, enabling informed decisions on necessary corrective measures.

– verification of the reliable operation of existing equipment for retention;

– replacement of components or of complete control systems;

– risks and consequences of oil leakage

Besides the above-mentioned points, the following facts may also influence the decision to replace or repair existing elements or systems:

– the assessment of operating costs;

– the assessment of repair costs;

– the operating and efficiency improvement potential of replacement versus repair;

– general safety and any demands required by authorities

The mechanical turbine controller consists of electrical components such as control valves, servomotors, pumps, and pendulum drives, while the electronic controller performs all control functions, including pilot control.

Electronic systems are sensitive to electrical-magnetic interference Therefore, the following shall be given special attention:

– quality of the power supply;

– immunity of the components to interference

When basic security measures are implemented and design rules are followed, testing can focus on verifying the actual operation of regulators Electrical tests are costly and require qualified personnel and specialized testing equipment, such as memory oscilloscopes with a cutoff frequency exceeding 100 MHz for measuring transient overvoltages These electrical tests are typically conducted as type tests For specifications on electromagnetic compatibility (EMC) testing, refer to IEC 61000-4-2, IEC 61000-4-3, and IEC 61000-4-6.

Pour réaliser les vérifications fonctionnelles sur site, il convient de choisir un espace situé centralement, calme (salle de commande) ó tous les signaux importants du processus sont disponibles

Dans le cas ó le régulateur n’est pas situé à proximité du groupe, il convient que des dispositions pour un fonctionnement d’urgence local soient prises

Il convient que la vérification de l'alimentation de puissance avec voltmètre et ampèremètre, oscilloscope et enregistreur de transitoires soit normalement réalisée en usine et est généralement limitée

– aux limites de tolérance et facteur d'ondulation;

The article discusses testing for sudden changes in power supply voltage and the application of a redundant energy storage voltage source after a power failure, as well as the behavior during reconnection For small, simple systems, these tests may be simplified.

6.4.4 Protection contre les surtensions et suppression des tensions parasites d’interférence

Les points suivants peuvent être vérifiés:

– la certification de l’équipement électronique concernant la compatibilité électromagnétique;

– l'isolation électrique de l’unité d’alimentation électrique pour les ensembles électroniques retirables;

– la séparation des contacts des signaux logiques et analogiques pendant le transport à la livraison et/ou le changement;

– la protection des câbles de connexion aux équipements périphériques;

– la séparation physique des câbles de signaux des câbles de puissance;

– la mise à la terre des parties métalliques inactives;

– la protection des équipements périphériques contre les surtensions par des éléments protecteurs;

– le câblage des éléments inductifs (bobines de relais, soupapes à solénọde) avec des éléments d’extinction (diode de roue libre, circuit RC, etc.)

Les connexions à la terre doivent être testées à l’aide d’ohmmètres En cas d'interférences, une mesure doit être effectuée aux extrémités des câbles de signaux avec un oscilloscope

By implementing essential safety measures and following guidelines, testing can focus on verifying the functionality of control systems Electrical testing is costly and necessitates qualified personnel and specialized equipment, such as storage oscilloscopes with a bandwidth of 100 MHz for measuring transient overvoltages Typically, electrical testing is conducted through type tests, and for details on electromagnetic compatibility (EMC) tests, refer to IEC 61000-4-2 and IEC 61000-4-3.

To carry out the functional checks on site, a centrally located, quiet place (control room) should be selected where all important signals of the process are available

If the controller is not located near the generating unit, provision for local emergency operation should be made

The check of the power supply with volt- and amperemeter, oscilloscope or transient recorder should normally be carried out in the workshop and is generally limited to

– tolerance limits and ripple factor;

The article discusses the testing of supply voltage switch-over and the activation of a redundant stored energy voltage following a power failure It also addresses the re-closing behavior of the system, noting that for smaller and simpler systems, these tests can be simplified.

6.4.4 Overvoltage protection and suppression of interference voltage

The following may be checked:

– certification of the electronic equipment with respect to EMC;

– the electric isolation of the power supply unit for withdrawable electronic parts;

– the contact separation of the binary and analogue signals during take-over and/or transfer;

– shielding of the cables to the peripheral devices;

– the physical separation of the signal cables from power lines;

– earthing of inactive metal parts;

– protection of the peripheral devices against overvoltages by protective elements;

– wiring of inductive devices (relay coils, solenoid valves) with extinguishing elements (free- wheeling diode, RC combination, etc.)

Ground connections are to be tested with ohmmeters In the event of interferences, a measurement is to be carried out at the ends of the signal cables with an oscilloscope

6.4.5 Essai du système d’interface avec le processus

Les signaux électriques relatifs à la position de l’actionneur, à la vitesse, à la puissance, au débit, aux hauteurs de chute (amont et aval), doivent être vérifiés vis-à-vis:

– de la caractéristique en circuit ouvert et de l’hystérésis (position de l’actionneur);

– de la dérive du zéro et de la sensibilité à la température;

– du filtrage (puissance, débit, niveau de l’eau);

– de l’acquisition des valeurs limites;

– de la surveillance des défauts, si disponible.

Essais des convertisseurs, amplificateurs et actionneurs

6.5.1 Convertisseurs électro-hydrauliques et électromécaniques

The converters discussed are crucial components that connect the electronic and hydromechanical parts of the regulation system Their significance lies in ensuring the overall functionality of the system Therefore, it is essential that their sensitivity, precision (including temperature stability), and dynamic behavior surpass the corresponding properties of the downstream amplification stages.

La caractéristique la plus importante à établir est le débit d’huile en fonction du signal de commande et de la chute de pression

Figure 4 – Débit d'huile Q en fonction de l'entrée de courant I et de la chute de pression ∆ p

The curves in Figure 4 should be recorded for various pressure differentials, while also noting the temperature and type of oil (viscosity grade) The flow rate can be measured using a reservoir or by employing a test servomotor.

D'autres mesures peuvent être effectuées pour vérifier le temps mort et les caractéristiques dynamiques

6.4.5 Test of the process interface system

The electrical signals for actuator position, speed, power, flow, head (up-stream and tail race) shall be checked for:

– open circuit characteristic and hysteresis (actuator position);

– zero drift and temperature sensitivity;

– filtering (power, flow, water level);

6.5 Test of converters, amplifiers and actuators

Converters serve as the crucial link between the electronic and hydro-mechanical components of a control system, significantly influencing its overall performance It is essential that these converters demonstrate superior sensitivity, precision (including temperature stability), and dynamic behavior compared to the subsequent amplifier stages.

(Examples: servo-valves, proportional valves.)

The most important characteristic is to establish the oil flow rate as a function of the command signal and of the pressure drop.

Figure 4 – Oil flow Q function of input current I and pressure drop ∆ p

To accurately assess the curves shown in Figure 4, it is essential to measure them under different pressure differences while also considering the oil temperature and viscosity grade Flow measurement can be conducted either through tank measurement or by utilizing a test servomotor.

Further measurements may be taken to verify the dead time and the dynamic characteristics

Servovalves and multi-stage proportional valves often feature an additional position adjustment loop for the second stage, which means they can only be tested with the corresponding electronic device.

NOTE 2 Si un arrêt d’urgence et une sécurité intégrée (par exemple arrêt en cas de défaut d’alimentation électrique) sont disponibles, il convient que leur fonction soit aussi essayée

NOTE 3 En gộnộral, pour atteindre la performance spộcifiộe, un signal vibratoire (effet ôditherằ) est appliquộ, qu’il faut également essayer

En principe, ces convertisseurs sont entraợnộs par un moteur ộlectrique (tournant ou linộaire)

Hydraulic turbines controlled by electric actuators consist of an electric motor, a gearbox, and an operating mechanism These converters are utilized to directly maneuver regulating components such as guide vanes, runner blades, injectors, and deflectors, or to drive systems equipped with control valves.

This type of servomechanism operates independently of the pressurized oil system Generally, it is suitable for small hydraulic turbines designed to withstand prolonged operation at overspeed in the event of a total power failure An appropriate safety mode return protection must be implemented to reduce the turbine's discharge to an acceptable level Examples of such protection include

– la fermeture des aubes directrices par une tendance à l’auto-fermeture;

– la fermeture de la vanne d’admission, avec les aubes directrices ouvertes;

Pour procéder à des essais, la mesure du courant d’entrée et des temps de manoeuvre est habituellement suffisante

Amplificateur électronique Transducteur de retour

Figure 5 – Convertisseur électro-hydraulique pour régulateur de classe élevée

Multi-stage servo and proportional valves typically include an additional position controller for the second stage, necessitating system testing alongside the associated electronic device.

NOTE 2 If an emergency trip and failsafe (for example shutdown in the event of power failure) are available, their function should also be tested

NOTE 3 Generally, to achieve the specified performance, a vibration (dither) signal is applied, which must also be checked

Electro-motor driven converters, whether rotating or linear, are essential for hydro turbines managed by electric actuators These systems typically include an electric motor, gearbox, and operating mechanism They are utilized for the direct actuation of regulating elements such as guide vanes, runner blades, nozzles, and deflectors, as well as for driving control valve systems.

This actuator operates independently of the oil pressure system, making it ideal for small hydro turbines It is specifically designed to endure prolonged runaway conditions in case of a complete electric supply failure To ensure safety, appropriate backup protection must be implemented to maintain turbine discharge at acceptable levels Examples of such protective measures include

– closing of guide vanes by self-closing characteristics;

– closing of inlet valve, with guide vanes open;

For testing purposes, measurement of current input and actuating times is usually sufficient

Figure 5 – Electro hydraulic converter for high grade control system

Figure 6 – Variation de la course ∆ s en sortie d’un convertisseur en fonction du courant d’entrée I

Il est de plus possible de vérifier

– les efforts de manœuvre en fonction de la pression d’huile;

Pendant ces essais, le signal vibratoire (dither) correspondant, il convient d’enregistrer les fuites d’huile, la température et la viscosité de l’huile

In certain control systems, electromechanical/electro-hydraulic converters may consist of an electro-hydraulic converter, a small pilot servomotor, and a position feedback sensor The pilot servomotor subsequently actuates the main (distributing) valve For measurement purposes, additional aspects do not need to be considered.

If these converters are designed as a compact device (for example, with a drawer control coil) featuring integrated hydraulic amplification, the relationship between the output stroke and the input current must be established or demonstrated through type testing, which also allows for the observation of hysteresis, as shown in Figure 6.

Il est de plus possible de vérifier

– les efforts de manœuvre en fonction de la pression d’huile;

Pendant ces contrôles, le signal vibratoire (dither) correspondant, il convient d’enregistrer les fuites d’huile, la température et la viscosité de l’huile

Figure 6 – Output stroke ∆ s of a converter versus input current I

It is furthermore possible to check

– the actuating forces as a function of the oil pressure;

During these checks, the corresponding vibration (dither) signal, oil losses, oil temperature and oil viscosity should be recorded

6.5.1.4 Two stage electromechanical/hydraulic control

In some control systems , electro mechanical/hydraulic converters can be composed of an electro hydraulic converter (see 6.5.1.2), a small pilot servomotor and a position feedback,

(see Figure 5), the pilot servomotor will then actuate the main control (distributing) valve For measurement, no additional aspects have to be considered

Compact converters, such as those designed with a plunger coil configuration and integrated hydraulic amplification, must demonstrate the relationship between output stroke and input current This correlation should be validated through type testing, which also reveals the hysteresis, as illustrated in Figure 6.

It is furthermore possible to check

– the actuating forces as a function of oil pressure;

During these checks, the corresponding vibration (dither) signal, oil losses, oil temperature and oil viscosity should be recorded

Les amplificateurs hydrauliques sont constitués de la soupape de distribution principale, du servomoteur et du retour d’asservissement

Pour les essais en usine, il est recommandé de raccorder la soupape de distribution principale au servomoteur Si le servomoteur n’est pas disponible, un servomoteur d'essai peut le remplacer

In addition to testing the limits of maneuvering time, friction, and sealing, it is essential to establish the characteristics of the main distribution valve This involves recording the valve's stroke, the pressure gain curve (which shows the increase in pressure in the control piping with the flow to the servomotor blocked), and the flow curve (which indicates the servomotor's maneuvering speed).

Figure 7a) – Courbes de pression p dans les tuyaux fermés en fonction du déplacement ∆ s du tiroir de la soupape (exemple type)

Hydraulic amplifiers consist of the main distributing valve, servomotor and feedback

For workshop checks, it is recommended to connect the main distributing valve with the servomotor If the servomotor is not available, a test servomotor can be used in its place

The characteristics of the main distributing valve must be established by testing the shortest actuating times, friction, and tightness These characteristics are recorded based on the valve spool stroke and include the pressure gain curve, which measures pressure build-up in the control lines when the flow to the servomotor is blocked, and the flow curve, which indicates the actuating speed of the servomotor.

Figure 7a) Pressure p curves in closed pipes versus displacement ∆ s of the valve spool (typical)

Figure 7b) – Vitesse du servomoteur en fonction du déplacement ∆ s du tiroir de la soupape (exemple type) Figure 7 – Courbes caractéristiques des soupapes de régulation

Essais sur site des caractéristiques du régulateur

Les différentes conceptions techniques et tâches fonctionnelles des centrales hydro- électriques doivent être prises en compte sans limiter pour cela la liberté de choix concernant les procédures d’essai

Dans les paragraphes suivants, il est donné quelques informations complémentaires à la

CEI 61362, qui ne sont pas en rapport direct avec les essais

The opening regulation is used to position the servomotor, functioning either as a downstream control command for primary regulation tasks, such as speed regulation, or as an operational mode for network regulation.

L’équipement de régulation est composé des éléments suivants: régulateur d’ouverture, convertisseur électro-hydraulique et servomoteur

– Signaux d’entrée: valeur de consigne d’ouverture, si nécessaire dépendant de la vitesse avec le statisme permanent, valeur effective de l’ouverture

– Signal de sortie: position du servomoteur

• rampe de fermeture du servomoteur;

Through a specialized design of turbine control, individual servomotors can be implemented on the guide vanes, along with synchronized electro-hydraulic controls, to ensure that all guide vanes remain in the same position.

La synchronisation est rộalisộe à l’aide de tringleries mộcaniques ou de faỗon ộlectronique suivant le système adopté

6.6.1.2 Régulation de vitesse (mode primaire)

L’équipement de régulation est composé: a) soit des éléments: régulateur de vitesse, convertisseur, amplificateur hydraulique, b) soit d’une combinaison série d’un régulateur de vitesse et d’un régulateur d’ouverture

• valeur de consigne de vitesse;

• valeur effective de la vitesse;

• si nécessaire, paramètres auxiliaires et/ou de perturbation (par exemple pression de la bâche spirale, niveau d’eau, hauteur de chute, puissance, position du servomoteur)

Limit values include permissible speed variations during load shedding, fluctuations in swelling or suction waves and pressure during load increases, decreases, and shedding, as well as maximum frequency variations when operating in an isolated network under defined load variations.

6.6 Site tests of controller characteristics

The different technical designs and operational tasks of Hydro Generating plants shall be taken into account without limiting the freedom of choice regarding the test procedures

In the following paragraphs, some additional information to IEC 61362 is given, not directly connected with the tests

The opening control serves to position the servomotor, either as a follow-up control in master control operations (for example speed control) or as an operating mode in network control

The control equipment consists of the elements: opening controller, electro hydraulic converter and servomotor

– Input signals: opening set-point value, if necessary speed dependent with permanent droop, actual opening value

A unique aspect of turbine control design involves the use of individual servomotors for guide vanes, along with electro-hydraulic controls that necessitate synchronization to ensure all guide vanes remain in the same position This synchronization can be accomplished through mechanical linkages or electronically, depending on the chosen system.

The control equipment either consists of: a) the elements: speed controller, converter, hydraulic amplifier, or b) a series arrangement of speed controller and opening controller

• if necessary auxiliary and/or disturbance parameters (for example spiral pressure, water level, head, power, servomotor position)

Limit values encompass the permissible speed variations during load rejection, as well as the surge, suction wave, and pressure fluctuations that occur during loading, unloading, and load rejections Additionally, they define the maximum frequency changes permitted during isolated operation with specified load variations.

6.6.1.3 Régulation de puissance (mode primaire)

L’équipement de régulation est composé: a) soit des éléments: régulateur de puissance, convertisseur, amplificateur hydraulique, b) soit d’une combinaison série d’un régulateur de puissance et d’un régulateur d’ouverture

• vitesse avec la dépendance du statisme permanent;

• si nécessaire, paramètres auxiliaires et/ou de perturbation (par exemple pression de la bâche spirale, niveau d’eau, hauteur de chute)

Limit values refer to the upper and lower power limits and prohibited ranges based on factors such as drop, cavitation, partial load conditions, and the dynamic state of the system, including the positioning of the balancing chimney.

6.6.1.4 Régulation de niveau d’eau (mode secondaire)

The regulation equipment consists of: a) elements such as a level regulator, converter, and hydraulic amplifier; b) a series combination of a level regulator and an opening regulator; or c) a series combination of a level regulator, flow regulator, and opening regulator.

• valeur désirée pour le niveau d’eau;

• valeur du niveau d’eau effectif;

• si nécessaire, grandeurs auxiliaires et/ou de perturbation (par exemple position des aubes directrices, marche en déchargeur de la centrale, verrouillage)

• valeur maximale du niveau d’eau amont;

• valeur minimale du niveau d’eau aval

6.6.1.5 Régulation de débit (mode secondaire)

L’équipement de régulation est composé: a) soit des éléments: régulateur de débit, convertisseur, amplificateur hydraulique, b) soit d’une combinaison série de régulateurs de débit et d’ouverture

• valeur désirée pour le débit;

• valeur du débit effectif (calculé le plus souvent);

• si nécessaire, grandeurs auxiliaires et/ou de perturbation (par exemple position des aubes directrices, niveau d’eau)

The control equipment either consists of: a) the elements: power controller, converter, hydraulic amplifier, or b) a series arrangement of power controller and opening controller

• speed dependent on permanent droop;

• if necessary, auxiliary and/or disturbance parameters (for example spiral pressure, water level, head)

– Limit values: upper and lower power limitation and banned regions dependent on head, cavitation, partial load and dynamic condition of the system (for example surge-tank situation)

6.6.1.4 Water level control (secondary mode)

Control equipment can be composed of various configurations, including: a) individual components such as a water level controller, converter, and hydraulic amplifier; b) a sequential setup of a water level controller paired with an opening controller; or c) a combination of a water level controller, flow controller, and opening controller arranged in series.

• if necessary, auxiliary and/or disturbance variables (for example gate position, discharge of station, locking)

• maximum value of head race water level;

• minimum value of tail race water level

The control equipment either consists of: a) the elements: flow controller, converter, hydraulic amplifier or b) a series arrangement of flow and opening controller

• actual flow value (mostly calculated);

• if necessary, auxiliary and/or disturbance variables (for example gate position, water level)

• vagues (intumescence et aspiration) liées aux variations de débit

6.6.2 Essais fonctionnels du système de régulation

Des essais doivent être effectués avec le système de régulation sans perturbation Les étapes les plus importantes sont les suivantes:

– activer le mode de régulation choisi;

– entrer des signaux d’essais définis, c’est-à-dire:

• changements de valeur de consigne des régulations de suivi (asservissements),

• grandeurs auxiliaires et de perturbation

Each operating point defined earlier must remain within the limits corresponding to the control range, such as the range of pressures and servo motor speeds.

– déterminer les critères d’évaluation des résultats atteints par optimisation des réglages du régulateur;

– conformément aux critères spécifiés pour la qualité de la régulation (par exemple déterminer le taux d’amortissement 0,8 < D < 1,1 pour un certain temps de réponse, mesurer l’aire de régulation (critère intégral) etc.);

– en respectant les valeurs et charges limites admissibles (par exemple écart minimal du système, limitation des variations de vitesse, surpressions et vagues du plan d’eau);

– en utilisant les incertitudes de mesure recommandées, conformément à l’Article 7

The damping ratio \( D \) (sometimes denoted as \( \zeta \)) is calculated using the formula \( D = 0.5 \left( \frac{T_1}{T_2} \right) \), where \( T_1 \) and \( T_2 \) are the time constants of a second-order filter A damping ratio of \( D = 0 \) indicates no damping, while \( D \geq 1 \) signifies an aperiodic response.

6.6.3 Détermination des paramètres du régulateur

Avant de faire les essais, il est important de

– déterminer les états d’équilibre de fonctionnement;

– sélectionner les amplitudes des échelons Les signaux d’entrée doivent être tels qu’ils ne peuvent pas être rendus invalides suite à des influences perturbatrices possibles;

– choisir des critères d’évaluation des résultats pour la détermination des paramètres, en particulier si des non-linéarités interviennent pendant les essais (par exemple limites de vitesse de manoeuvre)

Given that the behavior of regulation is typically better assessed through transient responses, and considering that measurements and evaluations can be costly, frequency response measurements should only be conducted in special cases The execution of such measurements should be outlined in specific agreements In principle, results from conventional tests are adequate.

• surge and suction waves in the event of flow changes

6.6.2 Functional test of the control system

Tests shall be carried out with an undisturbed control system The most important steps are:

– activation of the respective control mode;

– input of defined test signals, i.e.:

• set-point changes of the follow-up controls;

Each of the above defined operating points shall be within the control range maintaining limits (for example with respect to pressure range, servomotor speed etc.)

– determining the criteria for evaluating the results achieved by optimisation of the controller settings;

– according to specified criteria of control quality (for example determining the damping ratio

0,8 < D < 1,1 for a time response, measuring the control area (integral criterion) etc.);

– adhering to the admissible limit values and loads (for example minimum system deviation, limitation of speed changes, pressure surge, and surge and suction waves);

– using recommended uncertainties in measurement according to Clause 7

NOTE For the damping ratio D (or sometimes denoted as ζ) the formula D = 0,5 (T 1 /T 2 ) applies, whereby T 1 and

T 2 are the time constants of an element of second order delay; D = 0 is zero damping and D ≥ 1 is aperiodic damping

6.6.3 Determination of control system’s parameters

Prior to the test, the following is important:

– selection of step amplitudes The input signals shall be such that they cannot be invalidated by possible disturbing influences;

– choice of the evaluation criteria of the results for determination of the parameters, particularly if non-linearities occur during the tests (for example actuating speed limitations)

Frequency response measurements should be conducted only in specific cases due to the high costs associated with measurements and evaluations It is advisable to include the execution of these measurements in special agreements, while type test results should be deemed acceptable.

Insensitivity tests should only be conducted on peak power plant control systems and plants requiring precise frequency regulation It is essential to appropriately determine both an input and an output variable within the selected operating ranges.

For power regulation, the effective power value cannot be used as a measurement parameter Instead, the input variable is chosen to be either the frequency, which is continuously available, or the power setpoint as an additional input variable through permanent static conditions.

La localisation des insensibilités est la suivante:

The tests begin with the servomotor position as the output variable In certain cases, such as when individually controlling the guide vanes, the average value may be selected as the output variable.

– Si la sensibilité est insuffisante, mesurer étape par étape les variables de sortie amont, jusqu’à la sortie du régulateur

Tiêu đề	Hydraulic turbines – Testing of control systems
Chuyên ngành	Electrical Engineering
Thể loại	standards
Năm xuất bản	2005

Định dạng
Số trang	180
Dung lượng	8,71 MB