Overview of the governor 505E for the plant’s units

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Overview of the 505E governor: The 505E is a control system equipped with a 32-bit processor, and it can be used to control steam-driven turbines of the extraction type, extraction-replacement type, and replacement steam type. The 505E is designed for use in many different control applications, reducing costs and delivery time. In controlling special generators or mechanical equipment, with software that utilizes menus, the 505E can function as a single system unit or as a component that connects various systems under control. Operator Control Panel: The 505E combines the turbine control and operation panels into one unit. This control panel features two display screens, and there are 30 buttons on its front panel. The OCP is used in the 505E to enable online adjustment of the turbine/system operations; it employs a split-screen display in English, allowing the operator to see both their actions and the values set on the same display screen. Turbine Control Parameters: The 505E uses two control values (HP and LP) to regulate two sets of parameters as well as one additional parameter. These two sets of control parameters are the specific speed (or load) and the extraction/makeup steam pressure (flow rate); in any case, the 505E can handle them ； The inlet pressure or flow rate of the turbine, the exhaust (backpressure) pressure or flow rate, the pressure of the first-stage extraction, the output power of the generator, the input or output levels of the equipment, the pressures in the processes and intermediate stages of the unit equipment, or any parameters related to the turbine. Communications are based on two Modbus communication ports used on the operation panel; the 505E can be connected directly to Distributed Control Systems and/or CRTs. The communication port supports RS-232, RS-422, and RS-485, using ASCⅡ or RTU MODBUS communication protocols. Communication can be established between the 505E and DCS systems through hardware connections, as all 505E PID setpoints can be controlled via analog input signals; the interface protocol and control functions remain uninterrupted. Additional Features: The 505E also offers the following special functions: First-Out trip indication (a total of 5 trip inputs), critical speed avoidance (2 speed ranges), automatic sequencing for startup (hot start, cold start), dual dynamic speed/load control, zero-speed detection, a display of the speed peak value for overload tripping, and inter-system synchronization. When using the 505E, there are two operation modes for controlling it: program mode and run mode. The program mode is used to set options to initialize the operation of the turbine. Once control is initialized, the program mode is no longer used, unless the options or operations of the engine are changed. Once initialized, the turbine operates in its running mode from startup to shutdown. In addition to the program mode and the running mode, there is also a service mode used for performing system operations while the equipment is running. Refer to the service model in Volume 2. 505E INPUTS AND OUTPUTS 505E Inputs and Outputs Control Inputs: The two speed inputs can be configured as MPU (magnetic pickup units) using jumpers, or as approximate probe inputs. Six analog inputs are valid. One is for detecting the amount of extraction steam/supplemental steam. The remaining five are configurable. The sixth analog input is independent of the feedback circuit system and can be used in a self-sustaining power supply system. Sixteen contact inputs are valid, with four used for shutdown, restart, acceleration, and deceleration. If control is used as a generator, the other two related variables must be used as the generator circuit breaker and the circuit breaker interlock device. The additional ten contact inputs can be reset. If this unit is not used in a generator system, all the other twelve contact inputs can be reset. There are four function keys on the front panel of the controller. F1 and F2 are used for alarm and speed-over-limit testing respectively. F3 and F4 can be used for different control functions. Control Outputs: These represent the outputs of the two actuators, and they are used to determine the linearization curves for the HP valve and LP valve. Six 4-20mA outputs are provided for use with instruments or other digital display devices. There are eight Form-C delay outputs, of which six can be initialized, while the two are used for shutdown and alarm delay outputs. Control Communications manages two Modbus ports, which are used for connecting controllers; the protocol can be ASCII or RTU, and the communication can take place over RS-232, RS-422, or RS-485. The computer’s ports can be used for the initial storage of programs. A summary of the 505E functions is shown in Figure 2-1. This circuit can be used in control applications with special requirements. CONTROL OVERVIEW: Overview of control. The 505E digital speed regulator is designed to control extraction-type, extraction-reinforcement type, and reinforcement-type steam turbines. The difference among these turbines lies in their ability to introduce low-pressure steam that is lower than the inlet pressure and/or to discharge steam. A extraction-type unit can only discharge low-pressure (extraction) steam; a check valve is installed at the extraction end/pipe to prevent steam from flowing back into the turbine. ADMISSION: a steam-supplementing type of turbine that allows excess steam to enter the turbine via a low-pressure inlet. A extraction/feeding steam turbine enables low-pressure steam to be extracted or fed using system pressure. Turbogens with steam make-up functionality are equipped with stop valves or trip-and-throttle valves on the low-pressure steam pipeline, which prevent steam from entering in the event of a load rejection (trip) of the system. These types of turbines are used based on the requirements of the system. The functions are designed and implemented by the steam turbine manufacturer as required. The 505E has two independent effective control channels: speed/load and auxiliary control. The low signal outputs (LSS) of these two controls (speed/load signals) are supplied to the ratio/limiter ratio controller/virtual valve position controller. Additionally, for these channels, the speed/load controller can be used by other controllers such as cascade controllers. Where the set value of the speed controller is directly changed by the output of the cascade controller, the cascade controller is integrated into the speed controller. The auxiliary controller can be used as a control channel or a limitation channel. All three PID controls have the option to use analog input signals to change the setpoint position of theirs. The additional functions of the 505E include frequency control, isochronous loadsharing, critical speed avoidance, idle warm-up/rated target power control, and automatic startup. There are two sets of communication ports that use the Modbus protocol for monitoring and control. THE EXTRACTION TURBINES are steam-extraction turbines that are controlled through the interaction of high-pressure control valves and low-pressure control valves; the 505E controller can be set to operate a single turbine with automatic steam extraction. (505E can also operate the control valve and the primary extractor valve of the multi-stage extraction steam turbine.) A turbine with a single automatic steam extraction system has a high-pressure section and a low-pressure section, each controlled by a valve. Steam enters the turbine through a high-pressure valve (refer to Figure 2-2). Steam is extracted at the end of the high-pressure section and before the low-pressure valve. The low-pressure valve controls the inlet through which steam enters the low-pressure area; the steam that is redirected enters the extraction steam pipe. When the low-pressure valve is opened, most of the steam enters the low-pressure area, with a small amount being drawn out. In most cases, a extraction steam turbine needs to maintain stable turbine speed/load and extraction steam pressure. Changing the state of the high-pressure valve or the low-pressure valve will affect the speed/load of the turbine as well as the extraction steam. If the load or extraction of the turbine is to be changed, the states of both the high-pressure valve and the low-pressure valve must be altered to maintain a certain speed/load and extraction level. The minimum valve/process actuation amount for these two valves is automatically calculated by the 505E’s ratio logic based on the parameters of the turbine’s operating conditions. The Admission Turbines, which are steam-supplementing turbines, are controlled through the interaction of high-pressure and low-pressure control valves; the 505E controller can be programmed to operate a single automatic steam-supplementing turbine. A single automatic make-up steam turbine has a high-pressure section and a low-pressure section, each controlled by a valve. Steam enters the turbine through a high-pressure valve (refer to Figure 2-3). At the end of the high-pressure section and before the low-pressure valve. The low-pressure valve controls the inlet through which steam enters the low-pressure area; the diverted steam passes through the make-up steam pipe. When the low-pressure valve is opened, most of the steam enters the low-pressure area. In most cases, make-up steam turbines require stable turbine speed/load and make-up steam pressure/flow. Changing the state of the high-pressure valve or the low-pressure valve will affect the speed/load of the turbine as well as the extraction steam. If the load of the turbine or the amount of make-up steam needs to be changed, the states of both the high-pressure valve and the low-pressure valve must be altered to maintain a certain speed/load and make-up steam level. Based on the operating parameters of the turbine, 505E, the ratioing logic circuit automatically calculates the movement amounts of the two valves, thereby minimizing the interaction between the valves and the process. The extraction and admission turbine, also known as a extraction/compensation turbine, allows for automatic control through the interaction of the control valve (high pressure) and the extraction valve (low pressure); the 505E controller can be used to manage such turbines automatically. A turbine with a single automatic steam extraction/feeding system has a high-pressure cylinder and a low-pressure cylinder, each controlled by a valve. Steam enters the turbine through a high-pressure valve (refer to Figure 2-2). At the end of the high-pressure section and before the low-pressure valve, steam is extracted or introduced into the low-pressure cylinder. The low-pressure valve controls the amount of steam entering the low-pressure cylinder. When the low-pressure valve is opened, most of the steam enters the low-pressure cylinder, with a small amount being drawn out. In most cases, extraction steam turbines require maintaining stability in the turbine’s speed/load as well as the extraction/makeup steam pressure/flow rate. Changing the state of the high-pressure valve or the low-pressure valve will affect the speed/load of the turbine, as well as the extraction or intake of steam. If the load or extraction of the turbine is to be changed, the states of both the high-pressure valve and the low-pressure valve must be altered to maintain a certain speed/load and extraction level. The minimum valve/process actuation amount for these two valves is automatically calculated by the 505E’s ratio logic based on the parameters of the turbine’s operating conditions. SPEED CONTROL: Speed control requires a turbine speed signal obtained from one or two magnetic sensors or similar probes. The speed PID controller amplifies and compares this speed signal to generate a frequency/valve position output signal (via low-level signal selection). The speed control amplifier can also provide a programmable (selectable) attenuated feedback signal to enhance the stability of the turbine/generator system. This attenuated signal is proportional to the controller output signal or the system power generation load signal. The speed control setpoint can be adjusted by entering increase or decrease commands via the keyboard in front of the controller. The given value can also be set directly by entering a new value via the keyboard or through a Modbus communication connection. Furthermore, changing the speed setpoint of the simulated input signal enables remote control of the speed setting. Remote Speed Setpoint: The 4-20mA input is used to configure the remote adjustment of the auxiliary speed setpoint. In particular, this input is used to control the 505E external interface during the process, in order to adjust the turbine speed or load and thus control the related processes. The remote speed setpoint input directly affects the 505E’s speed setpoint. The maximum rate of the remote input signal that can change the speed setpoint is programmable. When the remote control speed setpoint is permissible, the speed setpoint will change at a very slow rate until the two values match. During this period, the speed will change at its maximum rate. The function of remotely setting the speed value can be enabled or disabled as needed via the keyboard on the front panel, through a remote connection or a communication link. AU*LIARY CONTROL – Auxiliary control is used to adjust parameters or set limits on them. An auxiliary PID controller can be used to control or limit load/power levels, as well as device input/output levels. Inlet pressure, extraction steam pressure, temperature, or other process variables that are directly related to the turbine load. The auxiliary input is a 4-20mA current signal. The auxiliary PID control amplifier compares the input signal with the set value to generate a control output signal for the digital low-signal select bus LSS. The low-signal selection bus sends a low signal to the ratio/limiter/ratio/virtual valve position logic circuit, which determines the position state of the HP and LP valves. The auxiliary control amplifier can also generate a programmable (selectable) attenuation feedback signal to improve system stability. The output signal of some auxiliary control amplifiers is fed back directly. The auxiliary set value can be adjusted by entering increase or decrease commands via the keyboard in front of the controller. It can be adjusted either through remote input or via a communication connection. The given value can be set directly via the keyboard or by entering a new given value using the Modus key. Additionally, the analog input can program the status of the remote auxiliary setpoint. Remote Aux Setpoint: Remote control for adjusting the auxiliary setpoint; an input signal of 4-20mA is used to remotely adjust the auxiliary setvalue. The remote control auxiliary setpoint input directly affects the auxiliary setpoint. When the remote control input signal can change the auxiliary setpoint, the maximum rate is programmable. When the remote control setpoint is permitted, the auxiliary setpoint will change at a very slow rate until the two setpoints match, at which point the setpoint can be allowed to reach the maximum speed. The remote control auxiliary function can be set to allowed or prohibited as needed via the panel keyboard, remote control input, or communication connection. The Load Sharing Input 505E can use an analog input to receive load sharing signals from Woodward’s Digital Synchronizer and Load Control (DSLC). This connection to the DSLC input allows for the control of shared load synchronization with any other system that uses a DSLC. Sum of the signals from the internal reference speed/load PID of 505E. Additionally, load sharing – the input from DSLC to 505E can be used for synchronization units and devices. CASCADE CONTROL: Cascade control can be used to regulate system processes that are influenced by the speed or load of the turbine. In particular, this controller is used as a turbine inlet or exhaust pressure controller. Cascade control is a PID controller that compares the 4-20mA process signal with the cascade setpoint. The PID controller adjusts the setpoint of the speed controller until the process signal matches the setpoint. Cascade control can also provide a programmable (selectable) attenuation feedback signal to improve system stability. The output signal of some cascade control amplifiers is fed back directly. The cascade setpoint can be adjusted by increasing or decreasing commands via the keyboard in front of the controller. It can be adjusted either through remote input or via a communication connection. Similarly, the given value can be set directly via the keyboard or by entering a new positioning point using the Modus key. Additionally, a remote cascade setpoint analog input can be programmed for the remote cascade setpoint. The 4-20mA input for Remote Cascade Setpoint is used to configure remote adjustment of the cascade setpoint. The remote control cascade setpoint input directly affects the cascade setpoint of the 505E. At the maximum rate, when the remote control input signal can change the cascade setpoint, the maximum rate is programmable and can be modified in operation mode. When the remote setpoint is permitted, the cascade setpoint will change at a very slow rate until the two settings match, at which point the setpoint can be allowed to reach the maximum speed. The remote cascade function can be set to allowed or prohibited as needed via the panel keyboard, remote input, or communication connection. EXTRACTION/ADMISSION CONTROL – Extraction/Admission (Extr/Adm) control involves using signals of (4-20mA) from pressure or flow transmitters to regulate the extraction and injection of steam. The Extr/adm PID controller compares the signal with the setpoint to generate an output signal for the Ratio/Limiter. The Extr/Adm control can also generate a programmable (selectable) attenuation feedback signal to improve the stability of the extraction steam control loop. The Extr/Adm set values can be adjusted by entering increase or decrease commands via the keyboard in front of the controller. It can be adjusted either through remote input or via a communication connection. Similarly, the point can be set directly by entering a new given value via the keyboard or through Modus. Additionally, a remote Extr/Adm setpoint analog input can be programmed to control the Extr/Adm setpoint. The 4-20mA input for Remote Extraction/admission Setpoint is used to configure remote adjustment of the Extr/Adm set values. The remote Extr/Adm setpoint input directly affects the 505E’s Extr/Adm setpoint. At the maximum rate, when the remote control is used to change the input signal and thereby adjust the set value of Extr/Adm, the maximum rate is programmable and can be changed during operation. When remote control changes of the set value are permitted, the Extr/Adm set value will change at a very slow rate until the two settings match, at which point the set value can be increased to the maximum speed. The remote setpoint function can be set to allowed or prohibited as needed via the panel keyboard, remote input, or communication connection. RATIO/LIMITER: The Ratio/Limiter obtains the input signal from the speed (or auxiliary) and the PID control for extr/adm. “The “ratio” logic uses these signals based on the turbine’s operating parameters to generate two output signals, one of which controls the HP actuator ； A controller for the LP actuator. “The “limiter” logic ensures that the actuator’s output remains within the turbine steam range. The Ratio logic controller regulates the interaction between the HP and LP valves in order to maintain the desired turbine speed/load as well as the extraction/admission pressure/flow rates. By controlling the interaction of valves, the ratio logic reduces the impact of one control process on other control processes. When a certain speed/load or extraction/admission causes the turbine to reach its operational limits, the limits logic controller restricts the HP or LP valves, prioritizing the maintenance of a certain speed/load or extraction/admission. Ratio/limiter Decoupling – Rate/virtual valve position decoupling: In most cases, extraction steam turbines need to maintain not only the speed/load of the turbine but also the pressure/flow rate of the extracted or supplied steam at constant levels. Changing the state of either the HP valve or the LP valve will affect the speed/load of the turbine, as well as the extraction or feed steam. If the load or the extraction/inlet steam needs to be changed, the states of both the HP and LP valves must change in order to maintain a constant speed and steam extraction/inlet. There are many situations where the rate is not satisfactory; in such cases, it is necessary to decouple the output of one or two valves. The 505E has three valid decoupling options: decouple HP (or inlet), decouple LP (or exhaust), or decouple both HP and LP. When controlling the inlet or exhaust pressure or flow rate, as well as the extraction/feeding pressure or flow rate, and when only the extraction needs to be changed while the inlet or exhaust conditions remain constant, it is necessary to regulate the interaction between the valves. Inlet (HP) decoupling is specifically used to control the turbine inlet pressure when the extraction or feed steam pressure/flow rate is fixed. If the inlet pressure changes, the states of both the HP and LP valves must change in order to maintain the inlet pressure as well as the extraction/makeup steam pressure. However, if the inlet conditions remain constant, only the extraction/supply steam needs to change (as a change in the extraction volume is required), and only the LP valve is adjusted to control the extraction/inlet steam. Exhaust (LP) decoupling is specifically used to control the turbine exhaust/backpressure when the extraction or feed pressure/flow rate is constant. If the exhaust steam needs to be changed, the states of both the HP and LP valves must be altered to ensure proper exhaust steam flow as well as suction/feed steam flow. However, if the exhaust conditions remain constant and only the extraction/suction volume needs to change, then only the HP valve is adjusted to control extraction/suction. HP and LP decoupling (HP&LP) is specifically used to control the turbine inlet pressure and the turbine exhaust pressure (or to control two independent variables related to the turbine/process). If the inlet pressure changes while the exhaust pressure remains constant, only the HP is adjusted. Similarly, when the exhaust pressure changes while the inlet steam pressure remains constant, only the LP valve will adjust. HP AND LP VALVE LIMITERS: High-pressure and low-pressure control valves; virtual valve position limits for HP and LP valves, to assist with starting up and shutting down. The virtual valve position can be adjusted via the keyboard, external switch box, or Modbus. When a command to increase or decrease is given, the virtual valve position increases or decreases accordingly at a set rate. Select the lower signal from the output of the HP valve’s virtual valve position and the ratio/limiter output signal. The low signal controls the state of HP, thereby limiting the maximum opening degree of the HP valve through the virtual valve position of HP. When applied to a extraction steam turbine, the higher signal is selected from the ratio/limiter and the LP valve virtual valve position output signals. When set as a make-up steam type or extraction/make-up steam turbine, select the low signal. Therefore, based on the settings, no selection is required; the virtual valve position of the LP valve limits its minimum or maximum opening degree. During the startup process, use the virtual valve position; refer to Chapter 4 for information on the startup process. The virtual valve position of the valve is also used to troubleshoot power issues in the system. If the 505E is considered to cause system instability, the virtual valve position of the valve can be used to manually control the valve opening. Care must be taken when using the virtual valve position of the valve in this way. Do not put the system in a critical state. STARTING FEATURES – The 505E offers three different startup mode options: automatic, semi-automatic, and manual. One of these modes must be set to control the turbine from the stopped state to minimum speed. Based on the startup process and the recommendations of the turbine manufacturer, set the startup mode and the minimum control speed of the governor. If a warm-up speed is set (warm-up/target or sequential start), the 505E provides automatic speed control and critical speed avoidance. Use a 505E keyboard, remote contact switch input, or Modbus communication to issue a “Run” command. Additionally, the input of the contact switch for the “Start Permissive” option can be set as a condition that prevents startup, such as when the quick-shut valve is not closed. Idle/Rated Warm-up/Target: By using the warm-up/target function, the operator can accelerate from the set warm-up speed to the set target speed at a specified rate. Selecting the warm-up speed or target speed set value can be done via the panel keyboard, through remote contact switches, or via ModBus communication. The warm-up/target function is also set to only the ramp-to-rated function (directly reaching the target speed). Auto Start Sequence: The operator can use the automatic start sequence to carry out the following operations: startup begins at a set low-speed warm-up speed, with the rotation speed maintained until the designated warm-up time is up; thereafter, the speed is increased to a set high-speed warm-up speed, which is maintained until that high-speed warm-up time expires; finally, the speed is increased to the set target (rated) speed. The warm-up time and acceleration rate are determined by whether the turbine is in a \"hot\" or \"cold\" state (depending on the duration of shutdown). When the turbine is between hot and cold states, the warm-up time and rate of temperature increase are interpolated using data from both the hot and cold states. If necessary, the automatic sequential startup process can be interrupted and resumed using the automatic sequential startup interrupt/resume command. To choose to interrupt or continue, the 505E keyboard, remote contact switch input (if set), or ModBus communication can be used. Additionally, the automatic sequential start function can be set to automatically interrupt waiting at each warm-up point. Critical Speed Avoidance: Many steam turbines need to avoid a certain speed or speed range (or pass through it as quickly as possible). In the 505E setting, there are two critical speed avoidance areas to choose from. This can be any speed range between the warm-up speed and the minimum governor speed. Whether it is the warm-up/target function or the automatic sequential startup function, a critical speed must be set for avoidance. In the critical speed avoidance zone, the 505E accelerates at the set critical lift rate and is not allowed to remain in that zone. If the turbine accelerates through the critical speed avoidance zone and the resulting severe vibrations exceed the allowable limits, a command to reduce the set speed is issued to bring the system back to a level below the lower limit of that avoidance zone. Keyboard and display: The panel of the 505E includes a keyboard and an LED display. The LED display has two rows with 24 segments each. Used to display operation parameters and fault handling data in English. The 30 keys fully enable all 505E controls, eliminating the need for an additional panel for operation ； Every turbine control function can be implemented using the 505E panel. Each key has the following function: SCROLL: A diamond-shaped key with arrows in the four corners in the center of the keyboard. In program mode or run mode, ＜＞ (left/right scrolling) moves the display left or right to the next function block. In program mode or run mode, the ∧ and ∨ keys move what is displayed in the function block up or down. SELECT: The select key is used to choose which row, the upper one or the lower one, is valid for controlling the display of the 505E. Valid rows that can be adjusted are marked with @. If both rows are adjustable (dynamic, data calibration mode), press the “Select” key to determine which row is valid for adjustment. The screen shows that only one row of parameters can be adjusted; the “Select” button and the @ symbol have no meaning. ADJ(adjust): In operation mode, “∧” increases the parameter, while “∨” decreases it. PRGM (program): When controlling pause, this key selects program mode. When in operation mode, this key selects program monitoring mode. In program monitoring mode, the program can only be viewed and not modified. RUN: Execute and run, or start up once the system is ready after booting. STOP: Once confirmed, pause the control of the turbine (operating mode). “\"Stop\" can be disabled through the service mode setting (under the \"Key\" option). RESET: Reset/clear the operating mode alarms and shutdown conditions. Pressing this key after pausing returns to the control mode (control parameters/press Run or Prgm). 0/NO: Type 0/NO or Prohibit. 1/YES: Type 1/YES to permit. 2/ACTR (actuator): Type 2 to display the actuator’s position status (operating mode). 3/CONT (control): Type 3 or display the controlled parameters (operation mode) ； Press the Scroll down arrow key to display information on the reason for the last shutdown, the priority of the steam map, the maximum speed achieved, and the local/remote control status (if in use). 4/CAS (cascade): Type 4 to display cascade control information (operating mode). 5/RMT (remote): Enter 5 or display remote speed change setpoint control information (operating mode). 6/LMTR (valve limiters): Enter 6 to display the virtual valve position information of the valve (operating mode). 7/SPEED: Type 7 to enter the speed control mode (operation mode). 8/AUX (auxiliary): Type 8 or display auxiliary control information (operation mode). 9/KW (load): Enter 9 to display the load or first-stage pressure information (operating mode). ./EXT/ADM (extraction/admission): Enter a decimal point or view the extraction/feeding steam information (operating mode). CLEAR: Clears the values entered for the program mode and operation mode, and displays its current mode. ENTER: Enter new data in program mode. In runtime mode, enter a specific value by typing directly. DYNAMICS (+/−): In operation mode, it monitors the dynamic values of parameters related to the status of control actuators. Dynamic adjustment through service mode settings (under the Key option) can be disabled. This key can also change the notation for data entry. ALARM (F1): When the light of the key is on, an alarm message is displayed (the last/nearest alarm). Press the Scroll down arrow key to display additional alarms. OVERSPEED TEST ENABLE (F2): Allows the speed to exceed the set maximum control speed, in order to test the electrical and mechanical overspeed protection mechanisms. F3 (Function key): The designated function key. F4 (Function key): The designated function key. EMERGENCY SHUTDOWN BUTTON: A large red octagonal button. This is the emergency stop button. Watchdog timer/CPU error control: The watchdog timer and CPU error circuit monitors oversee the operation of the microprocessor and its memory. If the microprocessor resets the timer incorrectly within 15 milliseconds of the last reset, the CPU’s error handling control will take action and trigger a reset. CPU reset: does not activate all delayed outputs, and turns off all milliampere outputs.