Geothermal power station steam pressure PCV valve group control method and system

Abstract

The invention belongs to the technical field of geothermal power station steam pressure valve group control, and relates to a geothermal power station steam pressure PCV valve group control method and system.The method comprises the steps that steam header rear pressure and demister rear pressure are obtained, and median selection is conducted on the three demister rear pressures; a control object is switched between starting and normal operation according to the steam turbine operation signal and the reset signal; performing proportional integral differential operation on the deviation between the control object and the pressure set value to obtain a total opening instruction; a fine adjustment control valve and exhaust valve set opening degree instruction is generated according to the split-ranging mapping and the valve opening sequence, and the valve opening sequence and the split-ranging relation are automatically reordered in the valve cutting-off automatic state; and when the steam turbine trips, the generator is subjected to load shedding or isolated island operation, a quick starting and keeping strategy is adopted, and after keeping is finished, proportional integral differential operation output is switched back. According to the technical scheme, the method is suitable for a geothermal power station steam discharge station, and cooperation of steam pressure stable adjustment and transient discharge under multiple working conditions can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of steam pressure valve group control technology for geothermal power plants, and specifically relates to a method and system for controlling steam pressure PCV valve groups in geothermal power plants. Background Technology

[0002] In existing technologies, steam pressure regulation at geothermal power plant steam emission stations typically relies on pressure measurement point acquisition, controller calculation, and PCV valve group execution. Closed-loop regulation of the main steam or emission pipeline pressure is used to meet overpressure protection and noise emission management requirements during turbine start-up, shutdown, and operation. However, existing PCV valve group control methods have some significant shortcomings in switching between pressure control objects under multiple operating conditions and in valve group coordinated regulation and matching.

[0003] In practical applications, during the period from the commissioning of the production well and start-up to grid connection and load bearing, the steam flow direction and pressure characteristics of the geothermal system change rapidly, and the load on the controlled objects and valve groups changes with the operating conditions. Existing control strategies often adopt fixed control object selection and fixed valve allocation relationships. After maintenance shutdown or valve characteristic drift, the distribution of adjustment intensity is easily unbalanced, which manifests as a weak level of pressure fluctuation suppression and a high frequency of valve action. Under sudden events such as tripping and load shedding, the consistency between pressure relief action and subsequent adjustment is low, which easily introduces secondary fluctuations.

[0004] Therefore, it is evident that existing technologies often suffer from problems such as weak overall regulation stability of steam pressure in geothermal power plants under multiple operating conditions and sudden disturbances, and low coordination between protection and pressure relief and subsequent pressure stabilization control. These are the shortcomings of existing technologies.

[0005] In view of this, it is very necessary to provide a method and system for controlling the steam pressure PCV valve group in a geothermal power plant to solve the above-mentioned defects in the prior art. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies in geothermal power plants, such as weak overall regulation stability of steam pressure under multiple operating conditions and sudden disturbances, and low coordination between protection pressure relief and subsequent pressure stabilization control. This invention provides a PCV valve group control method and system for geothermal power plants to solve these technical problems.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this application provides a method for controlling the steam pressure PCV valve group in a geothermal power plant, including: The pressure measurement values ​​after the steam header and after the demister are obtained. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. Based on the turbine operating signal and reset signal, the system switches between normal operating mode and start-up mode. In normal operating mode, the pressure measurement value after the demister is selected as the control object, and in start-up mode, the pressure measurement value after the steam header is selected as the control object. The total opening command is obtained by performing proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint. The system generates fine-tuning control valve opening commands and exhaust valve group opening commands based on the total opening command and preset segment mapping rules, and puts them into adjustment according to the preset valve opening sequence. When any valve is in the automatic cut-off state, the valve opening sequence and segment mapping rules are automatically reordered. When a turbine trip, generator load shedding, or islanding operation is detected, a rapid opening command is used to replace the total opening command, and the exhaust valve group is rapidly opened according to the reordered valve opening sequence and maintained for a preset duration. After the holding period ends, the replacement is canceled and the operation switches back to the proportional-integral-derivative (PID) calculation output.

[0008] By adopting the above technical solution, the control input is made robust to the drift and transient pulsation of the measuring points by selecting the median of the three pressure measuring points and introducing the pressure in both positions. This enables the formation of a valve group regulation and transient release coordination mechanism that matches the operating conditions of the steam discharge station of the geothermal power plant. This meets the requirements of high stability of steam pressure regulation and high coordination level of protection pressure relief and subsequent pressure stabilization control under multiple operating conditions and emergencies.

[0009] Specifically, the pressure measurement value after the demister, constructed based on the median of three measurement points, remains representative even under abnormal point interference, and together with the pressure measurement value after the steam header, provides an optional control basis, making the stability of the pressure control criterion stronger. Furthermore, by combining the turbine operating signal and reset signal for operating condition identification and switching of the control object, the start-up and normal operation phases adopt control benchmarks that better fit the actual steam flow path and pressure characteristics, thus ensuring consistent adjustment targets and smoother transitions across different phases. Subsequently, proportional-integral-derivative (PID) calculations are used to form a unified total opening adjustment quantity as a global adjustment command, balancing steady-state deviation elimination and dynamic following capability. Finally, based on a preset range mapping, the adjustment quantity is combined... The valves are rationally allocated to the fine-tuning control valves and exhaust valve groups, and are engaged in stages in conjunction with the preset valve opening sequence. This reduces the regulation coupling and opening jitter caused by multiple valves operating in parallel, and improves the consistency of valve group coordinated regulation. When a valve withdraws from automatic participation, the valve opening sequence and the split-range relationship are automatically reordered simultaneously, so that the regulation capacity of available valve resources is continuously connected and the stability of control gain distribution is maintained. Under sudden disturbances such as turbine tripping, generator load shedding, or islanding operation, the valves take over with priority by using a rapid opening command and maintain it for a preset duration to obtain timely and predictable pressure relief. After the maintenance ends, the valves automatically return to the proportional-integral-derivative output to restore fine pressure regulation, making the pressure relief action more consistent with subsequent regulation and the pressure fluctuation convergence faster.

[0010] As a preferred embodiment, the step of obtaining the pressure measurement value after the demister includes: performing a consistency judgment on the pressure values ​​of the three pressure measurement points; removing pressure measurement points whose deviation exceeds a preset deviation threshold when the consistency judgment is not established; and selecting the median value of the remaining pressure measurement points after removal to obtain the pressure measurement value after the demister.

[0011] By adopting the above technical solution, the reliability screening of the pressure measurement values ​​after the demister is achieved by using consistency discrimination and abnormal measurement point rejection mechanism. This can reduce the contamination of control input by single-point drift, transient spikes or sensor failures, making the pressure control basis more stable and improving the reliability of the selected control object.

[0012] Preferably, the steps for switching between normal operation mode and start-up mode based on turbine operating signal and reset signal include: latching the start-up mode and prohibiting switching to normal operation mode when turbine operating signal is invalid, and releasing latching and allowing switching to normal operation mode when reset signal is valid.

[0013] By adopting the above technical solution, the deterministic nature of mode switching is achieved by using the switching constraints of startup mode latching and reset unlocking. This can avoid the control target jump caused by frequent switching when the operating signal is unstable, making the pressure regulation process during startup smoother and improving the consistency of operating condition switching.

[0014] Preferably, when performing proportional-integral-differential (PID) operations to obtain the total opening command, the integral term of the PID operation is limited, and the accumulation of the integral term stops when the total opening command reaches the preset upper or lower opening limit.

[0015] By adopting the above technical solution, the anti-saturation control of proportional-integral-derivative operations is achieved through the limiting of integral term and the saturation stopping mechanism. This can suppress overshoot and recovery hysteresis caused by integral accumulation when the execution quantity is limited, making the dynamic response of the total opening adjustment more controllable and improving the consistency of steady-state convergence.

[0016] Preferably, the step of performing automatic reordering of the valve opening sequence includes: acquiring the in-service signal of each valve in the fine-tuning control valve and exhaust valve group, updating the valve opening sequence according to the in-service signal, and removing the valve in the automatic deactivation state from the valve opening sequence and triggering automatic reordering when any valve is in the automatic deactivation state.

[0017] By adopting the above technical solution and combining the in-service signal update and automatic valve removal mechanism to achieve self-adaptive maintenance of valve opening sequence, the valve group commissioning sequence can be matched with the available valve resources in real time and maintain the continuity of regulation, reducing the risk of fluctuation caused by valve group coordination imbalance after maintenance shutdown.

[0018] As a preferred option, the step of automatically reordering the segment mapping rules includes: obtaining the effective flow capacity parameters corresponding to each valve in the fine-tuning control valve and the exhaust valve group; redistributing the segment intervals of the preset segment mapping rules according to the effective flow capacity parameters; and ensuring that the exhaust valve group opening command is monotonically continuous with respect to the total opening command.

[0019] By adopting the above technical solution, the effective flow capacity parameters are used to redistribute the range and maintain the monotonically continuous opening command, so as to achieve a consistent mapping between the valve group's regulation capacity and the actual discharge capacity. This can improve the rationality of the valve group's gain distribution and reduce the sudden opening and pressure oscillation caused by the range boundary.

[0020] Preferably, the steps of generating the fine-tuning control valve opening command and the exhaust valve group opening command include: the fine-tuning control valve receiving continuous mapping across the entire range of the total opening command, and the fine-tuning control valve continuously receiving incremental allocation of the total opening command when any valve in the exhaust valve group is put into adjustment.

[0021] By adopting the above technical solution, the fine-tuning control valve continuously maps the entire range and continuously undertakes incremental allocation after the exhaust valve is engaged, realizing the coordinated superposition adjustment of the fine-tuning channel and the exhaust channel. This can maintain the fineness of small disturbance response in a large range of adjustment and reduce the adjustment dead zone caused by multi-valve switching.

[0022] Preferably, the step of replacing the total opening command with a quick opening command and maintaining it for a preset duration includes: determining the preset duration based on the preset load range to which the generator load belongs; determining whether the controlled object meets the preset recovery conditions during the maintenance period; and ending the maintenance early when the controlled object meets the preset recovery conditions.

[0023] By adopting the above technical solution, the holding time is determined according to the generator load range and the holding is exited in advance in combination with the recovery conditions, so as to realize the self-adaptive discharge rhythm control under sudden disturbances. It can take into account both rapid pressure discharge and excessive discharge suppression, making the transient pressure convergence process more stable and improving the consistency of post-event stabilization.

[0024] Preferably, the step of removing the substitution and switching back to the proportional-integral-differential operation output includes: applying a slope limit to the rapid opening command, restoring the total opening command after the slope limit transition is completed, and generating the exhaust valve group opening command according to the proportional-integral-differential operation output.

[0025] By adopting the above technical solution, a slope limit is applied to the rapid opening command and the total opening adjustment is restored after the transition is completed, so as to achieve a smooth connection from transient priority control to fine pressure stabilization control. This can reduce the opening step and secondary fluctuation at the moment of reversal, make the valve group action more continuous and improve the pressure control stability.

[0026] Secondly, this application also provides a steam pressure PCV valve group control system for a geothermal power plant, comprising: The pressure acquisition unit is used to acquire the pressure measurement values ​​after the steam header and after the demister. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. The mode switching unit is used to switch between normal operation mode and start-up mode based on the turbine operation signal and reset signal. In normal operation mode, the pressure measurement value after the demister is selected as the control object, and in start-up mode, the pressure measurement value after the steam header is selected as the control object. The PID calculation unit is used to perform proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint to obtain the total opening command. The split-range allocation unit is used to generate fine-tuning control valve opening commands and exhaust valve group opening commands according to the total opening command and preset split-range mapping rules, and to put them into adjustment according to the preset valve opening sequence. The automatic reordering unit is used to automatically reorder the valve opening sequence and the split-range mapping rules when any valve is in the automatic shut-off state; The transient control unit is used to replace the total opening command with a rapid opening command when a turbine trip, generator load shedding, or islanding operation is detected. It then causes the exhaust valve group to open rapidly in a reordered valve opening sequence and maintain the position for a preset duration. After the position is maintained, the replacement is canceled and the system switches back to the proportional-integral-derivative (PID) arithmetic output.

[0027] As can be seen from the above technical solutions, the present invention has the following advantages: This application provides a PCV valve group control method and system for steam pressure in a geothermal power plant. By selecting the median of three pressure measurement points and introducing pressure quantities in a dual-position manner, the control input is made robust to measurement point drift and transient pulsation. This enables the formation of a valve group regulation and transient release coordination mechanism that matches the operating conditions of the geothermal power plant's steam discharge station. This meets the requirements for high stability of steam pressure regulation and high coordination level of protection pressure relief and subsequent pressure stabilization control under multiple operating condition switching and emergency events. Attached Figure Description

[0028] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a steam pressure PCV valve group control method for a geothermal power plant provided by the present invention; Figure 2 This is a schematic diagram of a steam pressure PCV valve group control system for a geothermal power plant provided by the present invention.

[0030] The components include: 1. Pressure acquisition unit, 2. Mode switching unit, 3. PID calculation unit, 4. Split-range allocation unit, 5. Automatic reflow unit, and 6. Transient control unit. Detailed Implementation

[0031] Various embodiments of this disclosure are described more fully below with reference to the accompanying drawings. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0032] In the following, the terms “comprising” or “may include”, which may be used in various embodiments of this disclosure, indicate the presence of the disclosed functions, operations, or elements, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of this disclosure, the terms “comprising,” “having,” and their cognates are intended only to indicate a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or the possibility of adding one or more combinations of the foregoing.

[0033] To address the problems in steam pressure fluctuation convergence and the lack of consistency between protection actions and subsequent steady-state control in geothermal power plants during startup, load fluctuations, and sudden disturbances, particularly in scenarios involving steam emission and pressure stabilization control, this application discloses a steam pressure PCV valve group control method and system for geothermal power plants. These problems arise from issues such as weak stability of pressure acquisition criteria due to operating conditions and measurement point deviations, low consistency of control benchmarks with changing operating conditions, weak coordination and continuity of parallel control execution units when availability changes, and difficulty in meeting the high stability and predictability of steam pressure control required by geothermal power plants. By introducing a pressure control basis construction and self-adaptive control strategy oriented towards operating conditions, this method maintains the representativeness and consistency of control criteria at different operating stages, achieves coordinated allocation and continuous takeover of parallel control resources, and forms a unified control link of priority protection and steady-state regression under sudden disturbances. This improves the stability and response consistency of steam pressure control, enhances the reliability and maintainability of coordinated control, and further meets the requirements of geothermal power plants for stable steam pressure control and consistent action under multi-condition switching and sudden event conditions.

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] like Figure 1 As shown in this embodiment, a method for controlling the steam pressure PCV valve group in a geothermal power plant includes: Step S1: Obtain the pressure measurement values ​​after the steam header and after the demister. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. Step S2: Switch between normal operation mode and start-up mode based on turbine operation signal and reset signal, and select the pressure measurement value after the demister as the control object in normal operation mode, and select the pressure measurement value after the steam header as the control object in start-up mode; Step S3: Perform proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint to obtain the total opening command; Step S4: Generate fine-tuning control valve opening command and exhaust valve group opening command according to the total opening command and preset segment mapping rules, and put them into adjustment according to the preset valve opening sequence. When any valve is in the automatic cut-off state, the valve opening sequence and segment mapping rules are automatically reordered. Step S5: When a turbine trip, generator load shedding, or islanding operation is detected, replace the total opening command with a fast opening command and instruct the exhaust valve group to open rapidly according to the reordered valve opening sequence and maintain it for a preset time. After the holding period ends, the replacement is canceled and the operation switches back to the proportional-integral-derivative (PID) calculation output.

[0036] This embodiment robustly fuses key pressure signals from multiple measurement points to form a switchable pressure reference, suppressing the impact of measurement anomalies and transient pulsations on control criteria and ensuring the representativeness of the control basis across different operating stages. By adaptively selecting pressure stabilization targets based on unit operating conditions, the pressure regulation reference during startup and grid connection, as well as normal load operation, aligns with the actual steam flow path, thereby reducing control mismatch and pressure fluctuations introduced by operating condition switching. Simultaneously, a unified closed-loop regulation quantity is used as the core for hierarchical and coordinated allocation of valve group regulation resources, ensuring that minor fluctuations are handled by the fine-tuning channel while significant disturbances are handled by the emission channel. This reduces coupling jitter caused by multiple valves operating in parallel and improves pressure convergence consistency. Furthermore, when valves are removed from automatic participation or cut off for maintenance, resulting in changes in available actuators, the valve group participation relationship and regulation force distribution are self-organized and reconstructed to ensure continuous regulation capability and stable control gain distribution. In addition, under sudden events such as tripping, load shedding, or network isolation, a priority release and timed holding strategy is introduced, followed by a smooth return to normal pressure regulation. This makes the connection between protection actions and subsequent steady-state control stronger and pressure fluctuations converge faster, thus improving the overall stability, predictability, and maintainability of steam pressure control in geothermal power plants.

[0037] Hereinafter, steps S1 to S5 will be specifically described according to embodiments of this application.

[0038] In step S1, the core task is to generate a pressure input that can be used for pressure stabilization control and mode switching determination. The input is the original sampled value of the pressure measuring point after the steam header and the three pressure measuring points after the demister. The output is two types of robust pressure measurement results: the pressure measurement value after the steam header and the pressure measurement value after the demister. It also provides a consistent data caliber for the subsequent selection of the controlled object.

[0039] In this embodiment, the geothermal steam emission station consists of an exhaust pipeline and a PCV valve assembly. The PCV valve assembly includes four exhaust valves and one fine-tuning control valve. The exhaust pipeline connects to a rock silencer and ultimately discharges into the atmosphere. The four exhaust pipelines are configured with a capacity of 4 × 33%. Under this operating condition, pressure pulsation, measuring point drift, and transient disturbances directly affect the stability of the control loop. Therefore, in addition to reading the pressure after the single-point steam header, pressure sampling also requires voting and anomaly rejection for the three pressure measuring points after the demister.

[0040] Specifically, pressure measurements after the steam header and after the demister can be collected, with the pressure measurement after the steam header recorded as follows: The pressure values ​​at the three pressure measuring points after the demister are recorded as the demister pressure values. Pressure value after demister and the pressure value after the demister Pressure measurement after demister The result can be obtained by selecting the median value from three pressure measurement points, and can be written as:

[0041] in, This represents the median selection function.

[0042] In some embodiments of this application, to reduce the impact of single-point inaccuracies on median selection, consistency judgment can be performed on the pressure values ​​after the three demisters, and abnormal measurement points can be removed when inconsistencies are found. Specifically, consistency judgment can be performed on the pressure values ​​of the three pressure measurement points. The consistency judgment can use a range threshold criterion, that is, calculating the maximum value of the three pressure values. and minimum value and the preset deviation threshold Comparison, satisfaction Consistency is determined at the time of assessment; if consistency is not determined, pressure measurement points with deviations exceeding a preset deviation threshold can be removed. The removal rule can be: calculate the pressure value for each channel. Median of three-way pressure absolute deviation ,when The corresponding measurement point will be removed from the candidate set.

[0043] After elimination, median selection can be performed on the remaining pressure measurement points to obtain the pressure measurement value after the demister. When there are two remaining measurement points, the pressure measurement value after the demister can be the average of the two points. When there is only one remaining measurement point, the pressure measurement value after the demister can be the value of that single point, and a measurement point degradation flag can be set for subsequent stability constraints. For example, a preset deviation threshold is used. Can be taken to The representative value within the range is used to accommodate short-cycle pressure fluctuations after the demister and the accuracy boundaries of the instrument.

[0044] Thus, step S1 establishes a pressure input system of "dual-position sampling + voting rejection" for the pressure after the steam header and the pressure after the demister, ensuring that the measured pressure value after the demister... It possesses anti-drift and anti-pulsation capabilities, providing a stable and consistent pressure input basis for subsequent mode switching and proportional-integral-derivative control.

[0045] In step S2, the core task is to achieve self-adaptive switching of the pressure control object when the relevant state of the steam turbine changes. The inputs are operating state quantities such as steam turbine operation signal, steam turbine trip signal and reset signal, as well as the two types of pressure measurement results formed in step S1. The outputs are the current control object pressure and the current mode flag, and form latching and back-cut boundary conditions that can suppress jitter.

[0046] Specifically, the control logic sets two control modes: normal operation mode and start-up mode. The normal operation mode is used for the normal operating conditions of the steam turbine and tracks the pressure after the demister. The start-up mode is used when the steam turbine is not running or during the start-up process and tracks the pressure after the steam header. In this embodiment, the system can switch between the normal operation mode and the start-up mode based on the steam turbine operating signal and reset signal, and the mode flag is recorded as follows. ,in Indicates normal operating mode. This indicates the startup mode. In normal operation mode, the pressure measurement value after the demister can be selected as the controlled object, and the pressure of the controlled object is denoted as... ,when Time to take In the startup mode, the pressure measurement value after the steam header can be selected as the control object, that is, when... Time to take For example, the pressure of the controlled object in the startup mode can correspond to the pressure measuring point LMB2LBB11CP001, and the pressure of the controlled object in the normal operation mode can correspond to the three pressure measuring points LMB2LBB3CP004 / 005 / 006 after the demister and perform the three-in-one selection.

[0047] It should be further explained that, to suppress frequent switching between modes under boundary conditions, a latching and unlocking mechanism can be introduced, with turbine tripping as the mandatory entry condition for the start-up mode and reset as the permitted entry condition for the normal operation mode. When the turbine operating signal is invalid, the start-up mode can be latched and switching to the normal operation mode can be prohibited. An invalid turbine operating signal can be defined as a low-level turbine operating signal or a signal that has been continuously lost for more than a preset debouncing duration. The system determines that the latch will not be released even if a transient running signal appears after latching; however, it can be released and allowed to switch to normal operation mode when the reset signal is valid. A valid reset signal can be manually reset if the input is valid and meets the preset stability window. Determination. For example, de-shaking duration. Desirable to Stable window Desirable to This is to avoid erroneous switching caused by signal glitches.

[0048] At this point, step S2 is completed via "pattern flag". The "+latch / unlatch" switching system forms a stable and traceable control object pressure during turbine start-up, shutdown, and reset. The selection mechanism can suppress boundary jitter and provide a clear control object input basis for subsequent proportional-integral-differential operations.

[0049] In step S3, the core task is to convert the deviation between the controlled object pressure and the pressure setpoint into a total opening command that can drive multi-valve split-range regulation, with the controlled object pressure as the input. The pressure setpoint is used to output the total opening command, and an executable suppression strategy is established for integral saturation and output limiting to ensure the stability of pressure control.

[0050] Specifically, the pressure setpoint is denoted as The pressure setpoint can be configured as a fixed value or a segmented value depending on the operating conditions. For example, the pressure setpoint... Can be taken to The representative value within the range. Based on this, the pressure deviation is denoted as... In this embodiment, proportional-integral-differential (PID) calculations can be performed on the deviation between the controlled object and the pressure setpoint to obtain the total opening command. Its value range is to For ease of engineering implementation, a discrete form can be adopted with a sampling period. An update can be written as:

[0051]

[0052] in, Represents the discrete time sequence number and the scaling factor. Integral coefficient and differential coefficients Here are the proportional-integral differential parameters, and the integral state. For integration, Let be the amplitude limiting function, and the integral amplitude limiting boundary is... and The lower limit of the total opening command is The maximum opening size of the total opening size command is .

[0053] It should be further explained that, to prevent the integral term from accumulating further when the actuator reaches the opening boundary, thus causing a secondary overshoot after stabilization, the integral term can be limited and subjected to anti-saturation freezing. For example, the integral term of the proportional-integral-differential operation can be limited, i.e., by... and Constrained integral state ; and stop accumulating integral terms when the total opening command reaches the preset upper or lower opening limit. Limited to And pressure deviation Time can be ordered ,when Limited to And pressure deviation The points are frozen at the same time. .

[0054] For example, when the sampling period proportionality coefficient Integral coefficient Differential coefficients Pressure setpoint Control object pressure Pressure deviation The contribution of the proportional term is approximately If the integral state Current And the differential term is approximately Then the total opening command Approximately The total opening command will be entered into the subsequent segment mapping and trigger the fine-tuning control valve to take effect first.

[0055] At this point, step S3 controls the pressure of the object. With pressure set value pressure deviation Mapped to total opening instruction Furthermore, by using integral limiting and anti-saturation freezing to form a feasible voltage regulation operation link, it can reduce the risk of integral accumulation caused by the opening boundary and provide a continuous and controllable opening input basis for subsequent multi-valve split-range allocation.

[0056] In step S4, the core task is to convert the total opening command into an opening command that can be executed by the fine-tuning control valve and the exhaust valve group, and to perform self-adaptive reconstruction of the valve opening sequence and the range when the valve's in-service state changes. The inputs are the total opening command, the valve's in-service signal, and the effective flow capacity parameters. The outputs are the fine-tuning control valve opening command, the exhaust valve group opening command, the dynamic valve opening sequence, and the dynamic range boundary. It also ensures that the opening command remains monotonically continuous with respect to the total opening command to suppress pressure oscillation.

[0057] Specifically, the PCV valve assembly consists of five PCV valves and uses a split-range function to receive the total opening command for operation. The numbers of the five valves can be denoted as a set of numbers. Among them, PCV valve number 4 is a spare valve. In this embodiment, one PCV valve is configured as a fine-tuning control valve, and the remaining four PCV valves are configured as valves in the exhaust valve group to adapt to the coordination of small disturbance voltage stabilization and large disturbance venting. Based on this, the fine-tuning control valve opening command can be generated according to the total opening command and the preset segment mapping rule. and exhaust valve assembly opening command ,in These are the numbers corresponding to each valve in the exhaust valve group.

[0058] It should be noted that, to reduce the "opening step" caused by the alternating engagement of multiple valves, the fine-tuning control valve maintains continuous mapping across the entire range and undertakes high-frequency, small-amplitude adjustments. The exhaust valve assembly engages valve by valve according to its segmented range to provide a wide range of emission capabilities. Specifically, the fine-tuning control valve can receive continuous mapping across the entire range of the total opening command, for example, taking... Furthermore, by combining the effective flow capacity parameters of the fine-tuning control valve, its contribution to the total emission capacity is kept within a controllable range.

[0059] For example, the exhaust valve assembly can employ a preset range. , , , , The total opening command is mapped segmentally to the 0% to 100% stroke of each valve, forming a segmented linear, full-stroke control within each segment. Furthermore, the first... The starting point of a segment is denoted as the segment boundary. The end point of a segment is recorded as the boundary of the segment. and order , , , , , The first The exhaust valve number corresponding to the segment is recorded as the exhaust valve number. Then the exhaust valve opening command can be linearly mapped within the segment and set to zero outside the segment.

[0060] In this embodiment, valves can be adjusted one by one according to a preset valve opening sequence, denoted as follows: The order in which the exhaust valve numbers are assigned is given, only the exhaust valve number corresponding to the current segment is included. When the system enters the adjustment phase, the opening commands of the remaining exhaust valves are kept at 0%, thereby increasing the exhaust capacity sequentially and avoiding competition among multiple valves within the same period.

[0061] Furthermore, to ensure that the segment mapping remains consistent with the actual discharge capacity when valves are shut down for maintenance or fault clearance, the valve opening sequence and segment intervals can be automatically reordered and redistributed based on in-service signals and effective flow capacity parameters. In some embodiments of this application, the in-service signals of each valve in the fine-tuning control valve and exhaust valve group can be obtained. These in-service signals can be obtained from the valve's automatic shut-off state, maintenance state, or valve position feedback diagnosis, and the in-service state of each valve is recorded as the in-service state. Update the valve opening sequence based on the in-service signals, that is, update the preset valve opening sequence. Perform filtering and rearrangement to make Only included in active duty status The valve number is assigned and a preset priority constraint is maintained; when any valve is in the automatic shut-off state, the valve in the automatic shut-off state is removed from the valve opening sequence and an automatic reordering is triggered. After the reordering is triggered, the exhaust valve number mapping is regenerated. And refresh the segment boundaries.

[0062] Furthermore, the effective flow capacity parameters corresponding to each valve in the fine-tuning control valve and exhaust valve group can be obtained. The effective flow capacity parameter can be obtained by multiplying the valve's rated flow capacity, the valve opening-flow characteristic converted value, and the in-service attenuation coefficient. Based on this, the range intervals of the preset range mapping rule are reallocated according to the effective flow capacity parameter. This reallocation can employ capacity-weighted segmentation, i.e., applying it to the set of in-service exhaust valves. Calculate weights And based on this, a new segment width is formed. This allows valves with larger exhaust capacity to be assigned a wider total opening command range; furthermore, the exhaust valve group opening command is monotonically continuous with respect to the total opening command, that is, when the total opening command... When the pressure deviation changes continuously, the opening command of any exhaust valve Without reverse transition and satisfying the continuous connection of the left and right limits at the segment switching point, this can be achieved by introducing a small bandwidth transition interval at the segment boundary and imposing a maximum opening change rate limit on the opening command within the transition interval.

[0063] Furthermore, when any valve is in automatic shut-off mode, the valve opening sequence and the split-range mapping rules can be automatically reordered. The trigger priority of this automatic reordering can be set to "update the valve opening sequence first". Then, the segment boundaries are redistributed, and finally the exhaust valve opening command is refreshed to ensure the overall opening command is maintained. The mapping remains consistent with the actual emission capacity within the same sampling period.

[0064] In some embodiments of this application, when any valve in the exhaust valve group is engaged for adjustment, the fine-tuning control valve can continuously receive incremental allocations of the total opening command, that is, it maintains the opening command of the fine-tuning control valve even after the exhaust valve is engaged. Follow the total opening command It changes continuously, thus providing fine-grained compensation at the moment of switching between segments and engaging the exhaust valve, reducing pressure fluctuations and adjustment dead zones.

[0065] At this point, step S4 completes the process by issuing the total opening command. Mapped to fine-tuning control valve opening command With exhaust valve assembly opening command and in active duty With effective circulation capacity parameters Drive valve opening sequence The self-adaptive reconstruction of the segment boundary forms a valve group coordinated regulation system of "continuous fine adjustment + segment exhaust + automatic reordering", which can suppress the opening step caused by the segment boundary and provide consistent valve opening sequence boundary conditions for transient protection action.

[0066] In step S5, the core task is to prioritize pressure safety in the event of a sudden disturbance and smoothly return to pressure regulation after the holding period ends. The inputs are event signals such as turbine tripping, generator load shedding, islanding operation, and operating quantities such as generator load. The outputs are the rapid opening command, the holding timer status, the early exit judgment, and the total opening command after the back-cut transition. It also ensures the continuity and controllability between the rapid opening of the exhaust valve group and the subsequent stabilization process.

[0067] Specifically, when turbine tripping, generator load shedding, or islanding occurs, excess steam needs to be released quickly to prevent system overpressure. A rapid start-up command can be used when these situations are detected. Replace total opening command And during the event's validity period, make the alternative flag valid to enable the total opening command. The exhaust valve assembly is not directly driven at this time. Instead, the exhaust valve assembly is rapidly opened according to a reordered valve opening sequence and held for a preset duration. In this embodiment, when an event is triggered, four exhaust valves can be fixed in a rapid opening sequence and held for a preset duration to achieve rapid pressure relief. For example, exhaust valves numbered 0, 2, 3, and 4 can be fixed fully open and held for a preset duration. For example, the holding duration can be adaptively set according to the generator load range to balance rapid pressure relief with suppression of excessive pressure release.

[0068] In some embodiments of this application, a preset duration can be determined based on a preset load range to which the generator load belongs, and the generator load can be recorded as... The duration will be recorded as For example, it can be set when hour When hour .

[0069] It should be further explained that, to avoid pressure surge and deterioration of turbine-side operating conditions caused by continuing to operate at full capacity even after pressure has recovered, recovery conditions can be set and early termination of the holding period can be allowed. During the holding period, it can be determined whether the controlled object meets the preset recovery conditions. The recovery conditions can be determined by the pressure of the controlled object. Return to pressure setpoint Nearby and satisfying the stable window criterion, for example, satisfying And continue The above, of which To restore the threshold, To restore the stable window, the hold can be terminated early when the controlled object meets the preset recovery conditions. After the early termination, the substitution flag is removed and a back-cut transition begins. At the same time, after the hold ends, the substitution can be removed and the system can switch back to the proportional-integral-derivative (PID) operation output. To avoid secondary pressure fluctuations introduced by the abrupt change from the rapid opening command to the total opening command during the back-cut, a slope limit can be applied to the rapid opening command to form a smooth transition.

[0070] Furthermore, a slope limit can be imposed on the fast-start command, with the maximum rate of change denoted as... For quick start command To the total opening command The transition command is denoted as the transition opening command. It can be written as:

[0071] in, This indicates a bilateral limit on the increment, with the maximum rate of change. by count.

[0072] The total opening command can be restored after the slope limit transition is complete, i.e., when... When the value is less than the preset transition threshold and remains within the preset transition stability window, the substitution flag is disabled and the exhaust valve assembly is restarted by the total opening command; and the exhaust valve assembly opening command is generated by proportional-integral-differential calculation, which is the total opening command of step S3. Re-enter as input for step S4 split-range mapping and refresh the exhaust valve assembly opening command. This restores fine voltage regulation.

[0073] At this point, step S5 uses the quick start command triggered by the event. Replacement and generator load Segment retention time The strategy aims to achieve rapid depressurization and suppression of excessive discharge under sudden disturbances, and to exit early with recovery conditions and transition commands with slope limits. This constitutes a smooth back-cut mechanism, creating a continuous and controllable connection chain between the rapid opening of the exhaust valve assembly and the proportional-integral-derivative pressure regulation, providing a reliable control closed-loop boundary for the pressure safety and stable return of the entire process.

[0074] In summary, this method generates robust pressure input by performing consistency discrimination and median selection on multiple pressure measurement points after the demister, and adaptively switches the control object under changes in turbine operating conditions. It also generates continuous total opening commands through proportional-integral-derivative operations with integral limiting and anti-saturation constraints. Furthermore, it drives the redistribution of range intervals and automatic reordering of valve opening sequences using effective flow capacity parameters, ensuring that the fine-tuning control valve and exhaust valve group maintain monotonic and continuous coordinated regulation even under maintenance shutdown and capacity change conditions. Simultaneously, it introduces rapid opening and hold mechanisms and slope-limited back-cut mechanisms under transient conditions such as tripping, load shedding, or islanding operation. This reduces the risk of pressure overshoot and oscillation, decreases the probability of manual intervention and misoperation, and improves the certainty and repeatability of transient handling, thereby enhancing the safety, stability, and maintainability of steam pressure control in geothermal power plants.

[0075] It should be noted that, although the embodiments in this application are based on... Figure 1 Steps S1 to S5 are described sequentially, but this does not mean that steps S1 to S5 must be performed in a strict order. The reason this embodiment follows this order is... Figure 1 The order in which steps S1 to S5 are described is provided to facilitate understanding of the technical solutions of the embodiments of this application by those skilled in the art. In other words, in the embodiments of this application, the order of steps S1 to S5 can be appropriately adjusted according to actual needs.

[0076] In some embodiments of this application, a steam pressure PCV valve group control method for a geothermal power plant is applied to the steam pressure control scenario of a geothermal power plant steam exhaust station. Steam after the steam header is divided into two paths: one path enters the steam exhaust station and is discharged to the atmosphere via the PCV valve group after passing through a rock silencer; the other path enters the steam turbine after passing through a steam demister. The PCV valve group includes four exhaust valves and one fine-tuning control valve, and the exhaust pipeline is configured as follows: Capacity configuration.

[0077] In this embodiment, the start-up mode control object corresponds to the pressure measuring point LMB2LBB11CP001 after the steam header, and the normal operation mode control object corresponds to the three pressure measuring points LMB2LBB3CP004 / 005 / 006 after the demister and performs a three-in-one selection.

[0078] A complete implementation process may include the following steps: Step 1: After the production well is put into operation, the control side periodically collects pressure measurements after the steam header. Pressure values ​​of the three channels after the demister , , The pressure measurement value after the demister was obtained based on the mean of three values. It can be written as:

[0079] in, This represents the median selection function. For example, the pressure values ​​after the three demisters are respectively... , , At that time, the pressure measurement value after the demister Pressure measurement value after steam header .

[0080] Step two: When the turbine operating signal is invalid, enter the start-up mode and maintain this mode to control the pressure of the target object. Take the pressure measurement value after the steam header To control the pressure at the emission station, pressure setpoint Configure according to the startup phase goals.

[0081] For example, pressure setpoint Pressure deviation Pressure deviation It reflects the direction and magnitude of the current pressure deviation from the pressure setpoint.

[0082] Step 3, based on pressure deviation The total opening instruction is obtained by performing proportional-integral-differential operations. Furthermore, the integral term is subject to amplitude limiting and anti-saturation freezing to prevent accumulation when the opening reaches the upper or lower limit. For example, the sampling period... proportionality coefficient Integral coefficient Differential coefficients At that time, if the integral state has accumulated to The differential term is approximately: Then the total opening command Total opening command Used to characterize the overall emission capacity that the PCV valve assembly needs to provide.

[0083] Step four: Name the five PCV valves 0, 1, 2, 3, and 4, with valve 4 being the spare valve. The five PCV valves receive the total opening command according to the split-range function. And action; when the total opening command is in to During the interval, the opening degree of valve 0 is from Linear mapping to When the total opening command is in to During the interval, the opening degree of valve No. 1 is from Linear mapping to When the total opening command is in to During the interval, the opening degree of valve No. 2 is from Linear mapping to When the total opening command is in to During the interval, the opening degree of valve No. 3 is from Linear mapping to When the total opening command is in to During the interval, the opening degree of valve No. 4 is from Linear mapping to .

[0084] For example, the total opening instruction At that time, the opening command of valve No. 1 can be set according to... The calculation yields approximately The remaining valve opening commands remain unchanged. Fine-tuning control valve opening command The total opening command is continuously received across the entire range and used to compensate for minor pressure fluctuations near the segment switching.

[0085] Step 5: When the steam turbine is braked and ready to start and enter the operation phase, the pressure of the controlled object is... Pressure measurement after switching to demister To control the main steam pressure; when the turbine trip signal is issued, the pressure of the controlled object is... Automatic switching back to steam header pressure measurement value When the turbine reset signal is issued, the pressure of the controlled object... Allow manual switching to pressure measurement value after demister This switching process ensures that the proportional-integral-derivative (PID) calculations are always closed-loop adjusted around the pressure position most sensitive to the current operating condition.

[0086] Step 6: When a turbine trip, generator load shedding, or islanding operation is detected, quickly activate the command. Replace total opening command And according to the protection action logic, valves 0, 2, 3, and 4 are fixed at full open for rapid pressure relief; maintain for a certain duration. Based on generator load Determine when the generator load Maintain duration When the generator load Maintain duration .

[0087] For example, if the generator load occurs when the event occurs Then maintain duration After the quick start command is completed, the command will be deactivated. The algorithm replaces the input and applies a slope constraint to the back-cut process to smoothly recover the total opening command output by the proportional-integral-differential operation. This avoids secondary pressure fluctuations caused by a sudden drop in the opening of the exhaust valve.

[0088] Through the complete implementation process described above, this method can form a robust closed-loop input by selecting the median of the pressure measurement point and switching the controlled object between two types of operating conditions: startup and normal operation. Combined with integral limiting and anti-saturation constraints, it improves the stability of pressure regulation. Furthermore, through split-range mapping and valve opening sequence self-adaptation, it enables multi-valve coordinated regulation to remain continuously controllable under valve cut-off and capacity change conditions. At the same time, under transient conditions such as tripping, load shedding, or islanding operation, it achieves rapid pressure relief and smooth stabilization through rapid opening and slope-limited back-cut, reducing the risk of overpressure and the probability of pressure oscillation, and improving the safety, stability, and maintainability of steam pressure control in geothermal power plants.

[0089] It should be understood that the step numbers identified by "Step 1, Step 2" and other similar forms in the above embodiments are only used to distinguish different steps and do not limit the steps to be executed in the order of these numbers. The specific execution order of each step can be adjusted according to its functional requirements and the inherent logic in the actual application scenario. The above step numbers should not be interpreted as a limitation on the implementation process of the embodiments of this application.

[0090] like Figure 2 As shown, the following is an embodiment of a geothermal power plant steam pressure PCV valve group control system provided by this disclosure. This geothermal power plant steam pressure PCV valve group control system and the geothermal power plant steam pressure PCV valve group control method of the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the geothermal power plant steam pressure PCV valve group control system, please refer to the embodiments of the geothermal power plant steam pressure PCV valve group control method.

[0091] Based on the same concept, another embodiment of this application provides a steam pressure PCV valve group control system for a geothermal power plant, comprising: Pressure acquisition unit 1 is used to acquire the pressure measurement value after the steam header and the pressure measurement value after the demister. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. The mode switching unit 2 is used to switch between normal operation mode and start-up mode based on the turbine operation signal and reset signal. In normal operation mode, the pressure measurement value after the demister is selected as the control object, and in start-up mode, the pressure measurement value after the steam header is selected as the control object. PID calculation unit 3 is used to perform proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint to obtain the total opening command; The split-range allocation unit 4 is used to generate fine-tuning control valve opening commands and exhaust valve group opening commands according to the total opening command and preset split-range mapping rules, and to put them into adjustment according to the preset valve opening sequence. Automatic reordering unit 5 is used to automatically reorder the valve opening sequence and split-range mapping rules when any valve is in the automatic shut-off state; The transient control unit 6 is used to replace the total opening command with a rapid opening command when the turbine trips, generators shed loads, or islands are detected, and to make the exhaust valve group open rapidly in the reordered valve opening sequence and maintain it for a preset time. After the holding period ends, the replacement is released and the system switches back to the proportional-integral-derivative calculation output.

[0092] The above-disclosed embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any non-creative variations that can be conceived by those skilled in the art, as well as any improvements and modifications made without departing from the principles of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for controlling the steam pressure PCV valve group in a geothermal power plant, characterized in that, include: The pressure measurement values ​​after the steam header and after the demister are obtained. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. Based on the turbine operating signal and reset signal, the system switches between normal operating mode and start-up mode. In normal operating mode, the pressure measurement value after the demister is selected as the control object, and in start-up mode, the pressure measurement value after the steam header is selected as the control object. The total opening command is obtained by performing proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint. The system generates fine-tuning control valve opening commands and exhaust valve group opening commands based on the total opening command and preset segment mapping rules, and puts them into adjustment according to the preset valve opening sequence. When any valve is in the automatic cut-off state, the valve opening sequence and segment mapping rules are automatically reordered. When a turbine trip, generator load shedding, or islanding operation is detected, a rapid opening command is used to replace the total opening command, and the exhaust valve group is rapidly opened according to the reordered valve opening sequence and maintained for a preset duration. After the holding period ends, the replacement is canceled and the operation switches back to the proportional-integral-derivative (PID) calculation output.

2. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, The steps for obtaining the pressure measurement value after the demister include: performing a consistency judgment on the pressure values ​​of the three pressure measurement points; removing pressure measurement points whose deviation exceeds a preset deviation threshold when the consistency judgment is not established; and selecting the median value of the remaining pressure measurement points after removal to obtain the pressure measurement value after the demister.

3. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, The steps for switching between normal operation mode and start-up mode based on turbine operating signal and reset signal include: latching the start-up mode and prohibiting switching to normal operation mode when the turbine operating signal is invalid, and releasing the latch and allowing switching to normal operation mode when the reset signal is valid.

4. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, When performing proportional-integral-differential (PID) operations to obtain the total opening command, the integral term of the PID operation is limited, and the accumulation of the integral term stops when the total opening command reaches the preset upper or lower opening limit.

5. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, The steps for automatically reordering the valve opening sequence include: acquiring the in-service signals of each valve in the fine-tuning control valve and exhaust valve group, updating the valve opening sequence based on the in-service signals, and removing the valve in the automatic deactivation state from the valve opening sequence and triggering automatic reordering when any valve is in the automatic deactivation state.

6. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 5, characterized in that, The steps of automatically reordering the split-range mapping rules include: obtaining the effective flow capacity parameters corresponding to each valve in the fine-tuning control valve and the exhaust valve group; redistributing the split-range intervals of the preset split-range mapping rules according to the effective flow capacity parameters; and ensuring that the exhaust valve group opening command is monotonically continuous with respect to the total opening command.

7. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 6, characterized in that, The steps for generating the fine-tuning control valve opening command and the exhaust valve group opening command include: the fine-tuning control valve receiving continuous mapping across the entire range of the total opening command, and the fine-tuning control valve continuously receiving incremental allocation of the total opening command when any valve in the exhaust valve group is put into regulation.

8. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, The step of replacing the total opening command with a quick opening command and maintaining it for a preset duration includes: determining the preset duration based on the preset load range to which the generator load belongs; determining whether the controlled object meets the preset recovery conditions during the maintenance period; and ending the maintenance early when the controlled object meets the preset recovery conditions.

9. The method for controlling the steam pressure PCV valve group in a geothermal power plant as described in claim 1, characterized in that, The steps of canceling the substitution and switching back to the proportional-integral-derivative (PID) operation output include: applying a slope limit to the rapid opening command, restoring the total opening command after the slope limit transition is complete, and generating the exhaust valve group opening command according to the PID operation output.

10. A steam pressure PCV valve group control system for a geothermal power plant, characterized in that, include: The pressure acquisition unit is used to acquire the pressure measurement values ​​after the steam header and after the demister. The pressure measurement value after the demister is obtained by selecting the median value from the three pressure measurement points. The mode switching unit is used to switch between normal operation mode and start-up mode based on the turbine operation signal and reset signal. In normal operation mode, the pressure measurement value after the demister is selected as the control object, and in start-up mode, the pressure measurement value after the steam header is selected as the control object. The PID calculation unit is used to perform proportional-integral-derivative calculations on the deviation between the controlled object and the pressure setpoint to obtain the total opening command. The split-range allocation unit is used to generate fine-tuning control valve opening commands and exhaust valve group opening commands according to the total opening command and preset split-range mapping rules, and to put them into adjustment according to the preset valve opening sequence. The automatic reordering unit is used to automatically reorder the valve opening sequence and the split-range mapping rules when any valve is in the automatic shut-off state; The transient control unit is used to replace the total opening command with a rapid opening command when a turbine trip, generator load shedding, or islanding operation is detected. It then causes the exhaust valve group to open rapidly in a reordered valve opening sequence and maintain the position for a preset duration. After the position is maintained, the replacement is canceled and the system switches back to the proportional-integral-derivative (PID) arithmetic output.

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