A method for combined winter and summer supply of waste heat of a power plant based on a lithium bromide unit

Abstract

The application discloses a kind of winter and summer combined heat and power operation methods of power plant waste heat based on lithium bromide unit, and it relates to energy supply technology field, this method is by setting acquisition point on power plant waste heat combined heat and power system, real-time acquisition operating state data, and data combination is carried out in intelligent control system, obtains comprehensive state parameter group, when comprehensive state parameter group is simultaneously located in generation license surface and unit license surface, determine target operating state, and execute including pre-regulation phase, isolation phase, reconfiguration phase and convergence phase state transition control process method can improve the determination accuracy of winter heating operating state and summer cooling operating state, reduce energy interruption, temperature fluctuation and pressure difference impact in switching process, and improve system operation safety and stability.

Description

Technical Field

[0001] This invention relates to the field of combined energy supply technology, specifically a method for winter and summer combined energy supply of waste heat from power plants based on lithium bromide generating units. Background Technology

[0002] With the development of combined heat and power systems, regional energy systems, and industrial waste heat cascade utilization technologies, power plant waste heat recovery has gradually evolved from a single winter heating supply to a composite energy utilization mode that combines heating, cooling, and comprehensive scheduling. At the same time, the technology for combined winter and summer waste heat supply in power plants has gradually transitioned from traditional static operation to dynamic regulation, and the focus of the technology has shifted from optimizing single equipment to the coordinated control of the heat source side, unit side, pipeline side, and user side.

[0003] Currently, the operation of combined heat and power (CHP) systems in power plants is mostly based on seasonal calendars, single return water temperatures, or single load values ​​as switching criteria. This makes it difficult to simultaneously reflect the safety boundaries of the CHP system, leading to inaccurate determination of the target operating status and increasing the risk of erroneous switching, delayed switching, and unit crystallization. Furthermore, due to the lack of a unified migration logic between winter heating and summer cooling, the transition from old to new paths is difficult to smoothly connect, which can easily cause short-term power outages for users, fluctuations in supply and return water temperatures, and pressure differential shocks in the pipeline network. When the operating boundaries continue to shrink, existing technologies rely heavily on alarms or manual intervention, lacking a proactive, graded intervention mechanism that is integrated with the migration process. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the technical solution of this invention is as follows: A method for combined winter and summer power generation of waste heat from power plants based on lithium bromide generating units includes the following steps: S1. By setting up collection points on the power plant's waste heat cogeneration system, real-time data collection of operating status is achieved, and the data is transmitted to the intelligent control system. The intelligent control system then combines the operating status data to obtain a comprehensive set of status parameters. S2. The power generation permitting surface is determined based on the turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin. The unit permitting surface is determined based on the generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration. The comprehensive state parameter set is compared with the power generation permitting surface and the unit permitting surface. When the comprehensive state parameter set is simultaneously at both the power generation permitting surface and the unit permitting surface, the target operating state is determined. When the comprehensive state parameter set is not simultaneously at both the power generation permitting surface and the unit permitting surface, the current operating state is maintained. S3. After determining the target operating state, execute the state transition control process, which includes the pre-adjustment phase, isolation phase, reconstruction phase and convergence phase in sequence. S4. During the state transition control process, the continuous supply control strategy and the active safety intervention strategy are executed. The continuous supply control strategy maintains the continuous power supply to users by connecting the transitional backup branch in the power plant waste heat cogeneration system during the isolation and reconfiguration phases. The active safety intervention strategy divides the intervention level according to the unit's permissible surface and the margin of the power generation permissible surface. The intervention levels include pre-dilution level, bypass return level, slope limiting load reduction level, and migration freeze level, and corresponding control is executed according to the corresponding intervention level. When the output stability of the target operating state meets the preset conditions, the state transition is determined to be complete.

[0005] Furthermore, in S1, the power plant waste heat winter and summer combined supply system includes a vacuum circulating water system, steam drive branch, lithium bromide absorption unit, heating network, cooling network and intelligent control system. By setting up several collection points on the power plant's waste heat winter and summer combined supply system and installing collection equipment at these points, the operating status data of the lithium bromide unit is collected in real time, and the operating status data is transmitted to the intelligent control system via a wireless transmission network. Operating status data includes turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system inlet water temperature, vacuum circulating water system outlet water temperature, steam drive branch pressure, steam drive branch flow rate, generator temperature, generator pressure, absorber temperature, absorber pressure, lithium bromide solution concentration, heating network supply and return water temperatures, cooling network supply and return water temperatures, user heating load values, and user cooling load values. The operating status data is processed for time synchronization and unit unification to obtain a standardized dataset. The standardized dataset is then classified to obtain the power generation side status parameter group, the unit side status parameter group, the network side status parameter group, and the user side status parameter group. These are then combined in a preset order to establish a comprehensive status parameter group for the combined power supply system. The integrated state parameter set is then stored in the database of the intelligent control system in chronological order.

[0006] Furthermore, in S2, the intelligent control system reads the comprehensive state parameter set recorded in the database during the historical operating cycle, and extracts the historical values ​​of turbine exhaust pressure, condenser steam side absolute pressure, vacuum circulating water system temperature difference, steam drive branch pressure and steam drive branch flow rate from the comprehensive state parameter set. The historical value of the steam-driven branch pressure is calculated by comparing it with the preset minimum driving pressure threshold, and the historical value of the steam-driven branch flow rate is calculated by comparing it with the preset minimum driving flow rate threshold. The smaller of the two differences is taken as the historical value of the steam-driven branch margin. Then, by combining the historical values ​​of turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin with the equipment design operating range and commissioning calibration threshold, the preset power generation boundary parameter set is determined. Based on the preset power generation boundary parameter set, the permissible ranges for turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin are determined respectively. The range of values ​​that simultaneously satisfy the permissible ranges for turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin is determined as the power generation permissible surface.

[0007] Furthermore, in S2, the intelligent control system reads the comprehensive status parameter set recorded in the historical operating cycle from the database, and extracts the historical values ​​of generator temperature, generator pressure, absorber temperature, absorber pressure and lithium bromide solution concentration from the comprehensive status parameter set. The historical values ​​of generator temperature and generator pressure, combined with the safe operating range of the unit and the commissioning and calibration thresholds, determine the permissible range of the generator; The absorber's permissible range is determined by combining historical values ​​of absorber temperature and absorber pressure with the unit's safe operating range and commissioning calibration thresholds. Based on historical values ​​of lithium bromide solution concentration, combined with historical values ​​of generator temperature and absorber temperature, the lithium bromide solution concentration boundary is corrected to determine the permissible range of lithium bromide solution concentration. The range of values ​​corresponding to the generator's permissible range, the absorber's permissible range, and the lithium bromide solution concentration permissible range are then determined as the unit's permissible range.

[0008] Furthermore, in S2, the power generation permit surface and the unit permit surface are compared with the comprehensive status parameter set acquired in real time; When the generation-side state parameter in the integrated state parameter group is located at the generation permitting surface and the unit-side state parameter is located at the unit permitting surface, the target operating state is determined based on the network-side state parameter and the user-side state parameter in the integrated state parameter group. The target operating status includes winter heating operation status and summer cooling operation status; When the return water temperature of the heating network is lower than the preset return water temperature threshold and the user's heating load value is higher than the preset heating load threshold, the target operating state is determined to be the winter heating operating state. When the return water temperature of the cooling network is higher than the preset cooling return water temperature threshold and the user's cooling load value is higher than the preset cooling load threshold, the target operating state is determined to be the summer cooling operating state. When the comprehensive status parameter group does not meet the judgment conditions for winter heating operation status and summer cooling operation status, the current operation status shall be maintained.

[0009] Furthermore, in S3, when the target operating state is the winter heating operating state, the migration target of the state transition control process is to establish a heating path from the vacuum circulating water system to the heating network and to switch the lithium bromide unit to the heating operating mode. When the target operating state is summer cooling operation, the migration target of the state transition control process is to establish a steam drive branch to the lithium bromide unit, connect the cooling path of the cooling network, and switch the lithium bromide unit to cooling operation mode.

[0010] Furthermore, in S3, the state transition control process sequentially includes a pre-adjustment phase, an isolation phase, a reconfiguration phase, and a convergence phase; The pre-adjustment phase involves pre-load reduction control of the current operating load, pre-connection control of the branch corresponding to the target operating state, and pre-connection control of the transitional support branch. During the isolation phase, the corresponding heat source path and main branch of the current operating state are exited sequentially according to a preset switching order. The reconfiguration phase includes establishing heating and cooling paths corresponding to the target operating state, and performing path correction based on the target flow rate and target pressure difference corresponding to the target operating state. During the convergence phase, the target operating state load is increased according to the preset load ramp rate, and the transition protection branch is gradually withdrawn after the output stability of the target operating state reaches the exit condition of the transition protection branch.

[0011] Furthermore, in S4, the transitional protection branch is independently set up in the main heat source path and main circulation branch of the power plant waste heat winter and summer combined supply system; Transitional support routes include energy storage routes and bypass routes; The continuous power supply control strategy includes taking over the transitional backup branch before the isolation phase begins, continuously supplying power to users through the transitional backup branch during the isolation and reconstruction phases, and exiting the transitional backup branch after the preset takeover exit conditions are met during the convergence phase. The preset takeover exit conditions include continuous power supply on the user side, stable output of the target operating status, and the target flow rate and target pressure difference meeting the preset allowable deviation range.

[0012] Furthermore, in S4, the margin of the unit's permissible surface is defined as the minimum deviation value between the unit-side state parameters in the integrated state parameter group and the boundary of the allowable interval of the unit's permissible surface. The margin of the power generation permit surface is defined as the minimum deviation between the power generation side state parameters in the integrated state parameter set and the allowable interval boundary of the power generation permit surface. Intervention levels are determined based on the correspondence between the unit permit area and the power generation permit area margin and the first intervention threshold, the second intervention threshold, the third intervention threshold and the fourth intervention threshold, respectively; Pre-dilution control is executed when the pre-dilution level is reached. When the bypass reflux level is reached, bypass reflux control is executed; When the inclination rate reduction level is reached, inclination rate reduction control is implemented. When the migration freeze level is reached, state migration freeze control is executed.

[0013] Furthermore, in S4, when the output stability of the target operating state meets the preset conditions, the state transition is determined to be complete; The preset conditions include that the fluctuation range of the supply water temperature of the heating network or the supply water temperature of the cooling network is within a preset range, and the fluctuation range of the return water temperature of the heating network or the return water temperature of the cooling network is within a preset range, and the continuous operation time reaches a preset duration. When the output stability of the target operating state does not meet the preset conditions, the state transition control process is kept in the convergence phase, and the transition protection branch is kept connected. When the migration freeze level is reached during the convergence phase, state migration freeze control is executed. After the state transition is determined, the comprehensive state parameter group, target operating state, state transition duration, intervention level, and takeover duration for the current operating cycle are stored in the database of the intelligent control system as records for subsequent historical operating cycles.

[0014] The beneficial effects of this invention are as follows: 1. By collecting operational status data and establishing a comprehensive status parameter group, and then comparing the current status with the power generation permit surface and the unit permit surface, the power generation side boundary and the lithium bromide absorption chiller unit boundary can be verified simultaneously before the status switch. This can improve the accuracy of target operating status determination and reduce the risks of erroneous switching, delayed switching, and unit operation that are prone to occur when switching is based solely on a single temperature or load.

[0015] 2. By dividing the state transition control process into a pre-adjustment phase, an isolation phase, a reconfiguration phase, and a convergence phase, and by connecting transitional support branches during the isolation and reconfiguration phases, coupled with intervention level control based on permissible surface margin, the process of old path exit and new path establishment can be made smoother. This can reduce short-term power outages for users, fluctuations in supply and return water temperatures, and pressure differential shocks in the pipeline network, thereby improving the continuous power supply capacity and operational stability during the state transition process.

[0016] 3. By combining the comprehensive state parameter set with the dual-permission surface judgment mechanism, and further coordinating with the phased state transition, transitional guarantee branch, and graded intervention mechanism, the problems of "inaccurate switching judgment" and "unstable switching process" can be solved simultaneously. This not only ensures more accurate switching between winter heating operation and summer cooling operation, but also maintains continuous power supply to users during the switching process and implements proactive control in a timely manner when the boundary is compressed, thereby improving the overall safety, stability, and applicability of the power plant waste heat combined winter and summer power supply system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the method steps of the present invention; Figure 2 This is a schematic diagram of the overall structure of the power plant waste heat combined winter and summer power supply system of the present invention; Figure 3 This is a schematic diagram of the path switching for the summer cooling operation state of the present invention; Figure 4 This is a diagram illustrating the proactive safety intervention strategy of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 Please see Figures 1-4 This invention provides a method for combined winter and summer power generation of waste heat from power plants based on lithium bromide generating units, comprising the following steps: S1. By setting up collection points on the power plant's waste heat cogeneration system, real-time data collection of operating status is achieved, and the data is transmitted to the intelligent control system. The intelligent control system then combines the operating status data to obtain a comprehensive set of status parameters. S2. The power generation permitting surface is determined based on the turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin. The unit permitting surface is determined based on the generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration. The comprehensive state parameter set is compared with the power generation permitting surface and the unit permitting surface. When the comprehensive state parameter set is simultaneously at both the power generation permitting surface and the unit permitting surface, the target operating state is determined. When the comprehensive state parameter set is not simultaneously at both the power generation permitting surface and the unit permitting surface, the current operating state is maintained. S3. After determining the target operating state, the state transition control process is executed. The state transition control process includes the pre-adjustment stage, the isolation stage, the reconfiguration stage, and the convergence stage in sequence. Among them, the pre-adjustment stage is used to adjust the load of the current operating state and prepare the branch of the target operating state; the isolation stage is used to exit the heat source path and main branch corresponding to the current operating state; the reconfiguration stage is used to establish the heat source path and pipeline path corresponding to the target operating state; and the convergence stage is used to increase the load of the target operating state. S4. During the state transition control process, the continuous supply control strategy and the active safety intervention strategy are executed. The continuous supply control strategy maintains the continuous power supply to users by connecting the transitional backup branch in the power plant waste heat cogeneration system during the isolation and reconfiguration phases. The active safety intervention strategy divides the intervention level according to the unit's permissible surface and the margin of the power generation permissible surface. The intervention levels include pre-dilution level, bypass return level, slope limiting load reduction level, and migration freeze level, and corresponding control is executed according to the corresponding intervention level. When the output stability of the target operating state meets the preset conditions, the state transition is determined to be complete.

[0020] In this embodiment, a combined heat and power plant with 2×300MW extraction condensing units is used as the application scenario. The waste heat winter and summer combined supply system of the power plant serves residential areas, hospital buildings and office buildings. The system is equipped with a vacuum circulating water system, steam drive branch, lithium bromide unit, heating network, cooling network and intelligent control system.

[0021] In winter, it is used as a heat source for heating, while the steam-driven branch is used as a cooling source for cooling in summer. The vacuum circulating water system is connected to both the heating and cooling pipe networks to provide heating or cooling under different operating conditions.

[0022] To ensure continuous power supply to users during state transitions, the power plant waste heat cogeneration system is also equipped with a transitional backup branch. In this embodiment, the transitional backup branch adopts a combination of a bypass branch and an energy storage branch.

[0023] The intelligent control system communicates with each data acquisition point and connects with the actuators of the lithium bromide generator unit, steam drive branch, heating network, cooling network, and transitional backup branch.

[0024] In this embodiment, the operating boundary is first preset, the sampling period is set to 5s, and the refresh period of the comprehensive status parameter group is set to 60s; the historical operating cycle selects stable operating samples from the previous heating season and the previous cooling season as the basic samples; the difference between the inlet and outlet water temperatures of the vacuum circulating water system is defined as the vacuum circulating water system temperature difference; the smaller of the difference between the steam drive branch pressure and the preset minimum drive pressure threshold and the difference between the steam drive branch flow rate and the preset minimum drive flow rate threshold is defined as the steam drive branch margin.

[0025] Based on historical operating samples, equipment design operating range, and commissioning calibration thresholds, the permissible ranges corresponding to turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin are preset; at the same time, the permissible ranges corresponding to generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration are preset.

[0026] In order to determine the target operating status, the heating return water temperature threshold, cooling return water temperature threshold, user heating load threshold, and user cooling load threshold are preset, and the supply water temperature fluctuation range, return water temperature fluctuation range, and continuous operating time threshold required for output stability determination are also preset.

[0027] In S1, data collection points are set up on the heat source side, unit side, pipeline side, and user side of the power plant waste heat cogeneration system to collect real-time operating status data.

[0028] Specifically, the turbine exhaust pressure is collected at the turbine exhaust pipe section, the absolute pressure of the condenser steam side is collected at the condenser steam side, the inlet and outlet water temperatures are collected at the inlet and outlet of the vacuum circulating water system, the branch pressure and branch flow rate are collected at the steam drive branch, the temperature and pressure are collected at the generator and absorber of the lithium bromide unit, the solution concentration is collected at the lithium bromide solution circulation pipeline, the supply and return water temperatures are collected at the first station of the heating and cooling networks, and the heating load and cooling load values ​​are collected at the user side.

[0029] After all operating status data is transmitted to the intelligent control system, it is first processed for time synchronization, then for dimensional unification, and then integrated according to the heat source side, unit side, pipeline side and user side to form a comprehensive status parameter group for this control judgment.

[0030] In S2, the intelligent control system first delineates the power generation permit surface and the unit permit surface based on preset boundary parameters, and then compares the comprehensive state parameter set formed in S1 with the two permit surfaces.

[0031] The power generation permit is jointly limited by the turbine exhaust pressure, the absolute pressure on the steam side of the condenser, the temperature difference of the vacuum circulating water system, and the margin of the steam drive branch; the unit permit is jointly limited by the generator temperature, the generator pressure, the absorber temperature, the absorber pressure, and the lithium bromide solution concentration.

[0032] The intelligent control system is only allowed to enter the target operating state determination when both the power generation side state parameters in the integrated state parameter group are simultaneously located at the power generation permitting surface and the unit side state parameters are simultaneously located at the unit permitting surface.

[0033] If the integrated state parameter set does not meet the allowable conditions of the dual permissive surfaces, the current operating state is maintained and the state transition control process is not executed.

[0034] Provided that both permission surfaces are satisfied, the intelligent control system continues to read the network-side status parameters and user-side status parameters in the integrated status parameter group to determine the target operating status.

[0035] When the return water temperature of the heating network is lower than the preset heating return water temperature threshold and the user's heating load value is higher than the preset heating load threshold, the target operating state is determined to be the winter heating operating state; when the return water temperature of the cooling network is higher than the preset cooling return water temperature threshold and the user's cooling load value is higher than the preset cooling load threshold, the target operating state is determined to be the summer cooling operating state.

[0036] If neither of the above two conditions is met, the current operating state will be maintained.

[0037] The purpose of this setting is to reduce the probability of erroneous and delayed handovers by not using a single seasonal signal as the basis for handover, but by incorporating heat source capacity, unit safety, network status and user needs into a single judgment entry point.

[0038] In S3, once the target operating state is determined, the state transition control process begins.

[0039] The state transition control process includes a pre-conditioning phase, an isolation phase, a reconfiguration phase, and a convergence phase.

[0040] When the target operating state is winter heating operation, the migration goal of the state transition control process is to establish a heating path from the vacuum circulating water system to the heating network and to put the lithium bromide unit into heating operation mode; when the target operating state is summer cooling operation, the migration goal of the state transition control process is to establish a cooling path from the steam drive branch to the lithium bromide unit and connect it to the cooling network, and to put the lithium bromide unit into cooling operation mode.

[0041] During the pre-adjustment phase, the intelligent control system first pre-reduces the load of the current operating state and prepares for the pre-connection of the target operating state branch and the transition protection branch. During the isolation phase, the heat source path and main branch corresponding to the current operating state are exited sequentially according to the preset switching order; During the reconfiguration phase, the heat source path and pipeline path corresponding to the target operating state are established, and the target flow rate and target pressure difference are corrected. During the convergence phase, the target operating load is increased according to the preset load ramp rate, so that the system gradually approaches the target operating condition.

[0042] By breaking down the state transition control process into the four stages mentioned above, the original abrupt switching action can be transformed into a continuous and correctable process control action, reducing the impact on the pipeline network and the user side.

[0043] In S4, continuous supply control strategy and proactive safety intervention strategy are executed synchronously throughout the entire state transition control process.

[0044] The continuous power supply control strategy is used to connect the transitional guarantee branch during the isolation and reconstruction phases to maintain the continuous power supply to users. In this embodiment, the transitional guarantee branch is connected before the start of the isolation phase, remains connected during the convergence phase, and exits after the preset exit condition is met.

[0045] It should be noted that transitional support routes include energy storage routes and bypass routes.

[0046] The energy storage branch includes a heat storage / cold storage unit, an energy storage circulation pump, an energy storage branch inlet valve, and an energy storage branch outlet valve. The inlet of the energy storage branch is connected to the return water main of the heating network or the return water main of the cooling network, and the outlet of the energy storage branch is connected to a user-dedicated branch.

[0047] The bypass branch includes a bypass circulation pump, a bypass regulating valve, and a bypass check valve. One end of the bypass branch is connected to the main water supply pipe of the heating network or the main water supply pipe of the cooling network, and the other end of the bypass branch is connected to the user's pre-distribution main pipe.

[0048] Before the isolation phase begins, the intelligent control system first connects the energy storage branch, and then connects the bypass branch. During the isolation and reconfiguration phases, the intelligent control system keeps both the energy storage branch and the bypass branch connected simultaneously. After the preset takeover exit conditions are met during the convergence phase, the intelligent control system first reduces the output ratio of the bypass branch, and then reduces the output ratio of the energy storage branch.

[0049] The energy storage branch is used to provide users with heat or cold energy reserves, and the bypass branch is used to buffer the flow and pressure difference on the user side, thereby maintaining the continuity of energy supply to users during the exit of the heat source path and the establishment of the target path.

[0050] The proactive safety intervention strategy is based on the permissible area margin of the generating unit and the permissible area margin of power generation to determine the intervention level.

[0051] The unit permissible margin is defined as the minimum deviation between the unit-side state parameters in the integrated state parameter group and the boundary of the allowable interval of the unit permissible margin. The power generation permissible margin is defined as the minimum deviation between the power generation-side state parameters in the integrated state parameter group and the boundary of the allowable interval of the power generation permissible margin.

[0052] Based on the relationship between the margin and the intervention thresholds at each level, the intelligent control system performs pre-dilution, bypass reflux, slope-limited load reduction, or migration freeze control respectively to avoid forced switching under boundary compression conditions.

[0053] Therefore, conventional passive protection actions can be shifted forward to proactive, graded intervention actions, enabling the state transition control process to continue operating within the safety boundary.

[0054] When the output stability under the target operating state meets the preset conditions, the state transition is considered complete.

[0055] In this embodiment, the output stability is judged by comprehensively considering at least the fluctuation range of the supply water temperature, the fluctuation range of the return water temperature, and the duration of continuous stable operation under the target operating state.

[0056] If the output stability does not meet the preset conditions, the state transition control process will remain in the convergence phase and the transition protection branch will be kept connected; if the unit's permissible surface margin or the power generation permissible surface margin further decreases to the migration freeze level during the convergence phase, then the state transition freeze control will be executed.

[0057] With this determination method, the completion of the state transition is not based on the simple arrival of time, but on the condition that "the target operating state has been stably established", thereby improving the engineering applicability and control reliability of the method.

[0058] This embodiment establishes a complete closed loop for the combined winter and summer power generation method of power plant waste heat by setting up a comprehensive state parameter group, dual permissive surfaces, a phased state transition control process, transition protection branches, and a graded active safety intervention strategy.

[0059] This method is applicable not only to the switching scenario between winter heating and summer cooling of vacuum circulating water systems, but also to regional energy systems that require priority to ensure continuous energy supply to users.

[0060] The overall technical effect is as follows: under the premise of meeting the operating boundaries of the power plant main unit and the safety boundaries of the lithium bromide unit, it can realize the controlled switching between winter heating operation and summer cooling operation, and reduce the risks of power supply interruption, temperature fluctuation and unit operation during the switching process.

[0061] Example 2 Please refer to Figures 1-4 Specifically: In S1, the power plant waste heat winter and summer combined supply system includes a vacuum circulating water system, steam drive branch, lithium bromide absorption unit, heating network, cooling network and intelligent control system. By setting up several collection points on the power plant's waste heat winter and summer combined supply system and installing collection equipment at these points, the operating status data of the lithium bromide unit is collected in real time, and the operating status data is transmitted to the intelligent control system via a wireless transmission network. Operating status data includes turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system inlet water temperature, vacuum circulating water system outlet water temperature, steam drive branch pressure, steam drive branch flow rate, generator temperature, generator pressure, absorber temperature, absorber pressure, lithium bromide solution concentration, heating network supply and return water temperatures, cooling network supply and return water temperatures, user heating load values, and user cooling load values. The operating status data is processed for time synchronization and unit unification to obtain a standardized dataset. The standardized dataset is then classified to obtain the power generation side status parameter group, the unit side status parameter group, the network side status parameter group, and the user side status parameter group. These are then combined in a preset order to establish a comprehensive status parameter group for the combined power supply system. The integrated state parameter set is then stored in the database of the intelligent control system in chronological order.

[0062] In this embodiment, a combined heat and power plant equipped with 2×300MW extraction condensing units is used as the application scenario. The waste heat winter and summer combined supply system of the power plant serves residential areas, hospital buildings and office buildings.

[0063] The system includes a vacuum circulating water system, a steam-driven branch, a lithium bromide absorption chiller, a heating network, a cooling network, and an intelligent control system. Data collection points are arranged on the heat source side, the chiller side, the network side, and the user side of the system.

[0064] The simulation operation was verified over a continuous 21-day operating cycle, with the first 11 days being the winter heating condition and the last 10 days being the summer cooling condition.

[0065] The data acquisition cycle is set to 5 seconds, the transmission cycle to 5 seconds, the data fusion cycle of the intelligent control system to 60 seconds, and the database entry cycle to 60 seconds. The rated circulation flow rate of the vacuum circulating water system is 8400 m³ / s. 3 The rated steam pressure of the steam-driven branch is 0.42 MPa, and the rated steam flow rate is 13.5 t / h. The rated heat output of the lithium bromide absorption chiller is 17.6 MW in winter heating mode and 15.9 MW in summer cooling mode.

[0066] Regarding the setting of the collection points, the collection points for the turbine exhaust pipe section are set at the measuring point location outside the exhaust manifold of the low-pressure cylinder of the turbine, and an exhaust pressure sensor is installed there; The absolute pressure monitoring point for the steam side of the condenser is set at the pressure measuring port of the upper cavity of the steam side of the condenser, and a vacuum detection instrument is installed thereon. The inlet and outlet sampling points of the vacuum circulating water system are respectively set on the inlet main pipe before entering the condenser and the outlet main pipe after leaving the condenser, and temperature sensors are installed on them respectively. The steam drive branch sampling point is set at the straight pipe section behind the steam regulating valve, and a pressure sensor and a flow meter are installed there; the generator sampling point is set at the generator shell side and steam side interface, and a temperature sensor and a pressure sensor are installed there. The absorber sampling point is set at the measuring point location on the absorber shell side, and a temperature sensor and a pressure sensor are installed there. The lithium bromide solution circulation pipeline sampling point is set at the solution pump outlet pipe section, and an online concentration detector is installed; The sampling points for the water supply and return pipe sections of the first station of the heating network are set at the main water supply pipe and the main return pipe of the first station, respectively, and temperature sensors are installed thereon. The sampling points for the water supply and return pipe sections of the first station of the cooling pipeline network are set at the main water supply pipe and the main return pipe of the first station, respectively, and temperature sensors are installed thereon. User-side data collection points are set up at the hospital's heat exchange station and air conditioning terminal main pipe, and user heating load and cooling load values ​​are collected through energy management terminals.

[0067] All of the above-mentioned data acquisition devices are connected to the intelligent control system via a wireless transmission network. The wireless transmission network used is a dedicated industrial wireless network for the factory area, and the single packet transmission delay is controlled within 0.8 seconds.

[0068] In order to make the "running status data" in this embodiment a unified input that can be used for subsequent judgment, this embodiment first performs time synchronization processing on the collected data.

[0069] The specific method is as follows: using the internal clock of the intelligent control system as a unified reference clock, the data uploaded by different collection points within the same 60s fusion cycle are aligned according to the timestamp; when the upload time of a certain collection point is within 2s earlier than the reference clock, the most recent sampled value is used to fill in the gap; when the upload time is within 2s later than the reference clock, the current value is retained and the previous sampled value is marked as an expired value; when a certain collection point is missing more than two samples within a fusion cycle, the status of the collection point is marked as a low-confidence state, and a data compensation flag is triggered at the same time.

[0070] This process enables the parameters of each acquisition point within the same fusion cycle to correspond to the same operating state section.

[0071] The dimensionless processing is completed using the interval normalization method, which maps different dimension parameters to the interval of 0 to 1 according to the maximum and minimum value normalization method.

[0072] The temperature difference of the vacuum circulating water system is calculated from the inlet temperature and outlet temperature of the vacuum circulating water system.

[0073] After completing time synchronization and unit unification processing, the intelligent control system generates a standardized dataset.

[0074] Subsequently, the standardized datasets were categorized according to parameter source and control object: The turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system inlet temperature, vacuum circulating water system outlet temperature, vacuum circulating water system temperature difference, steam drive branch pressure, and steam drive branch flow rate are classified into the generator-side state parameter group. Generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration are classified into the unit-side status parameter group; The supply and return water temperatures of the heating network and the cooling network are classified into the network-side status parameter group; the user heating load value and the user cooling load value are classified into the user-side status parameter group.

[0075] After classification, the generator-side status parameter group, the unit-side status parameter group, the network-side status parameter group, and the user-side status parameter group are combined in a preset order to form a comprehensive status parameter group.

[0076] To facilitate subsequent permission surface calculation and migration control, the integrated state parameter group in this embodiment is represented by a data structure arranged in a fixed order as follows: Ω=[Ge,Gu,Gn,Gl] Where Ω represents the integrated state parameter group, Ge represents the generator-side state parameter group, Gu represents the unit-side state parameter group, Gn represents the network-side state parameter group, and Gl represents the user-side state parameter group.

[0077] The integrated state parameter set formed in each cycle is stored in the intelligent control system database in chronological order for use in the subsequent construction of power generation permitting surfaces and unit permitting surfaces.

[0078] After synchronizing the above operating status data with time, the intelligent control system calculates the temperature difference of the vacuum circulating water system as 4.9℃, completes the dimension unification processing, and writes it into the power generation side status parameter group, the unit side status parameter group, the network side status parameter group, and the user side status parameter group respectively, and finally forms the comprehensive status parameter group for the current period and completes the database storage.

[0079] Before establishing the power generation permitting surface, unit permitting surface, and target operating status determination threshold, the intelligent control system first establishes a method for determining parameter boundaries and thresholds.

[0080] The method for determining parameter boundaries and thresholds includes steps such as screening historical stable operating samples, reading equipment boundaries, calibrating debugging thresholds, determining overlapping intervals, and updating thresholds.

[0081] In the historical stable operation sample screening step, the intelligent control system reads the comprehensive status parameter group of the previous heating season and the previous cooling season from the database, and removes communication missing samples, manual forced switching samples, safety interlock triggered samples, and key parameter out-of-bounds samples to obtain historical stable operation samples.

[0082] In the equipment boundary reading step, the intelligent control system reads the design operating range of the steam turbine, condenser, vacuum circulating water system, steam drive branch, and lithium bromide absorption unit.

[0083] In the debugging threshold calibration step, the intelligent control system determines the debugging calibration threshold range for each parameter based on stable operating samples from low-load, medium-load, and high-load segments.

[0084] In the overlapping interval determination step, the intelligent control system determines the common overlapping interval of the historical stable operation sample interval, the equipment design operating range, and the debugging calibration threshold range as the corresponding parameter allowable interval.

[0085] In the threshold update step, after the new operating cycle is completed, the intelligent control system writes the comprehensive state parameter group that has not triggered safety interlocks, has not been manually forced to switch, and whose output stability meets the preset conditions into the historical stable operation sample library, and updates the corresponding parameter permission range and target operating state judgment threshold according to the preset update cycle.

[0086] Example 3 Please refer to Figures 1-4 Specifically: In S2, the intelligent control system reads the comprehensive state parameter set recorded in the database during the historical operating cycle, and extracts the historical values ​​of turbine exhaust pressure, condenser steam side absolute pressure, vacuum circulating water system temperature difference, steam drive branch pressure and steam drive branch flow rate from the comprehensive state parameter set. The historical value of the steam-driven branch pressure is calculated by comparing it with the preset minimum driving pressure threshold, and the historical value of the steam-driven branch flow rate is calculated by comparing it with the preset minimum driving flow rate threshold. The smaller of the two differences is taken as the historical value of the steam-driven branch margin. Then, by combining the historical values ​​of turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin with the equipment design operating range and commissioning calibration threshold, the preset power generation boundary parameter set is determined. Based on the preset power generation boundary parameter set, the permissible ranges for turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin are determined respectively. The range of values ​​that simultaneously satisfy the permissible ranges for turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin is determined as the power generation permissible surface.

[0087] In S2, the intelligent control system reads the comprehensive status parameter set recorded in the historical operating cycle from the database, and extracts the historical values ​​of generator temperature, generator pressure, absorber temperature, absorber pressure and lithium bromide solution concentration from the comprehensive status parameter set. The historical values ​​of generator temperature and generator pressure, combined with the safe operating range of the unit and the commissioning and calibration thresholds, determine the permissible range of the generator; The absorber's permissible range is determined by combining historical values ​​of absorber temperature and absorber pressure with the unit's safe operating range and commissioning calibration thresholds. Based on historical values ​​of lithium bromide solution concentration, combined with historical values ​​of generator temperature and absorber temperature, the lithium bromide solution concentration boundary is corrected to determine the permissible range of lithium bromide solution concentration. The range of values ​​corresponding to the generator's permissible range, the absorber's permissible range, and the lithium bromide solution concentration permissible range are then determined as the unit's permissible range.

[0088] Based on the power generation permit surface and the unit permit surface, a comparison is made with the comprehensive status parameter set acquired in real time; When the generation-side state parameter in the integrated state parameter group is located at the generation permitting surface and the unit-side state parameter is located at the unit permitting surface, the target operating state is determined based on the network-side state parameter and the user-side state parameter in the integrated state parameter group. The target operating status includes winter heating operation status and summer cooling operation status; When the return water temperature of the heating network is lower than the preset return water temperature threshold and the user's heating load value is higher than the preset heating load threshold, the target operating state is determined to be the winter heating operating state. When the return water temperature of the cooling network is higher than the preset cooling return water temperature threshold and the user's cooling load value is higher than the preset cooling load threshold, the target operating state is determined to be the summer cooling operating state. When the comprehensive status parameter group does not meet the judgment conditions for winter heating operation status and summer cooling operation status, the current operation status shall be maintained.

[0089] In this embodiment, the same application scenario used in Embodiment 1 is used for illustration.

[0090] In this embodiment, the so-called "historical operating cycle" refers to the period of time during which the system operates continuously and stably without triggering safety interlocks, exceeding the limits of key parameters, or undergoing manual forced switching under winter heating and summer cooling conditions.

[0091] In this embodiment, 42 consecutive winter stable operating days and 37 consecutive summer stable operating days are selected as the historical operating cycle, and historical samples are extracted from the comprehensive status parameter group that has been established in Example 2 and stored in the database in chronological order.

[0092] To ensure the usability of historical samples, sample screening and cleaning are performed first: if any key parameter is missing twice or more within a certain fusion cycle, the corresponding comprehensive state parameter group will not be included in the permission surface construction sample; if the temperature fluctuation of the heating or cooling network supply and return water exceeds the preset range within the same fusion cycle and the duration is less than 10 minutes, it is considered a disturbance cycle and will not be included in the permission surface construction sample; if the generator pressure, absorber pressure, or lithium bromide solution concentration deviates significantly from the design operating range, the corresponding sample will also not be included in the permission surface construction.

[0093] After screening, there were 31,824 valid historical samples in winter and 27,416 valid historical samples in summer.

[0094] All the above valid samples are stored in the integrated state parameter group structure in Example 2. Therefore, the state parameters of the power generation side, the unit side, the network side, and the user side can be retrieved and analyzed in a unified manner under the same data structure.

[0095] Through this approach, this embodiment ensures that the establishment of the permission surface is not based on subjective experience values, but on the joint constraints of real historical operating behavior and equipment security boundaries.

[0096] The process for establishing a power generation permit is as follows: The intelligent control system first extracts historical values ​​of turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, steam drive branch pressure, and steam drive branch flow rate from historical samples. The vacuum circulating water system temperature difference continues to use the definition in Example 2, that is, the difference between the vacuum circulating water system inlet temperature and the vacuum circulating water system outlet temperature. The historical value of the steam drive branch margin is not directly read from the field, but is further calculated based on the steam drive branch pressure and steam drive branch flow rate in the historical samples.

[0097] It should be noted that the steam-driven branch is not put into operation as the main heating path during winter heating operation, but is kept in standby mode. Standby operation refers to the steam-driven branch maintaining a preset standby pressure and preset standby flow rate, and keeping the branch valve group, measuring points and actuators in a responsive state to ensure that the system has the ability to quickly switch from winter heating operation to summer cooling operation.

[0098] The preset standby pressure threshold and preset standby flow rate threshold are jointly determined based on the steam drive branch design parameters, the lithium bromide absorption turbine manufacturer's technical manual, and the on-site commissioning results. In this embodiment, the preset minimum drive pressure threshold is 0.31 MPa, the preset minimum drive flow rate threshold is 9.5 t / h, the preset standby pressure is 0.18 MPa, and the preset standby flow rate is 4.9 t / h.

[0099] Although the steam-driven branch does not assume the main power supply function in standby operation, it can maintain the accessibility of the backup drive side, thereby shortening the drive establishment time for target migration and reducing the impact of state migration in subsequent summer cooling operation.

[0100] Specifically, the preset minimum driving pressure threshold and the preset minimum driving flow threshold are not fixed values ​​that are set directly, but are determined jointly based on the basic parameters of the steam drive branch and the lithium bromide absorption unit, as well as the results of on-site commissioning.

[0101] Specifically, firstly, the manufacturer's technical manual, steam drive branch design documents, equipment nameplate parameters, and factory performance test data of the lithium bromide absorption chiller unit are read to obtain the theoretical minimum driving pressure range and theoretical minimum driving flow range of the unit under rated operating conditions. Then, after the system is installed, on-site commissioning is carried out under low-load cooling preparation conditions, gradually reducing the steam drive branch pressure and steam drive branch flow, and recording the generator temperature, generator pressure, absorber temperature, absorber pressure, unit cooling output, and continuous stable operation time at each commissioning point. When a significant decrease in cooling output, excessive fluctuations in generator thermal state, weakened absorption capacity of absorber, or inability of unit to operate stably for a preset duration occurs at a certain commissioning point, the steam drive branch pressure and steam drive branch flow rate corresponding to the previous commissioning point are taken as the minimum stable drive conditions, and respectively determined as the preset minimum drive pressure threshold and preset minimum drive flow rate threshold.

[0102] Under the conditions of the 2×330 MW cogeneration unit and the 18.4 MW / 16.7 MW dual-condition lithium bromide absorption unit corresponding to this embodiment, after the above calibration, the preset minimum driving pressure threshold is 0.31 MPa and the preset minimum driving flow threshold is 9.5 t / h.

[0103] Within each historical sample period, the pressure difference is first obtained by subtracting the preset minimum driving pressure threshold from the historical value of the steam drive branch pressure, and then the flow difference is obtained by subtracting the preset minimum driving flow threshold from the historical value of the steam drive branch flow. The smaller of the two differences is taken as the historical value of the steam drive branch margin for that period.

[0104] The reason for adopting the "smaller value" is that the steam drive capability is constrained by both pressure and flow rate. When either side approaches the threshold, it will weaken the effective drive capability of the steam drive branch for the lithium bromide absorption unit. Therefore, the smaller value can better represent the conservative available margin.

[0105] In the valid historical samples of this embodiment, the historical values ​​of turbine exhaust pressure are mainly distributed between 5.3 kPa and 8.2 kPa, the historical values ​​of condenser steam-side absolute pressure are mainly distributed between 5.6 kPa and 8.6 kPa, the historical values ​​of vacuum circulating water system temperature difference are mainly distributed between 3.9℃ and 6.5℃, and the historical values ​​of steam drive branch margin are mainly distributed between 0.13 and 0.44.

[0106] The intelligent control system then superimposes and verifies the aforementioned historical values ​​with the equipment's design operating range and calibration thresholds to form a preset power generation boundary parameter set. In this embodiment, the equipment's design operating range is used to provide hard boundaries, while the calibration thresholds are used to provide flexible control boundaries during actual operation.

[0107] It should be noted that the preset power generation boundary parameter set is not directly generated from the real-time parameters in the current sampling period, but is determined by the stable operating samples in the historical operating period, the equipment design operating range, and the on-site commissioning calibration threshold.

[0108] The design operating range of the equipment is obtained by reading the design documents, factory technical manuals and installation and commissioning documents corresponding to the steam turbine, condenser, vacuum circulating water system and steam drive branch. The on-site commissioning calibration thresholds were obtained by conducting multi-load segment commissioning under winter heating and summer cooling operation conditions, collecting parameter samples during the stable operation phase, and then performing statistical analysis on the stable operation samples.

[0109] Meanwhile, the design operating range and calibration threshold of this equipment also serve to determine the initial preset power generation boundary parameter set and the initial preset unit boundary parameter set based on the equipment design operating range and calibration threshold when the historical operating cycle data in the database is 0 or the number of valid historical samples does not reach the preset number of samples. This ensures that the boundary of the comprehensive state parameter set can be determined when the system is first put into operation. As the operating cycle increases, the comprehensive state parameter set recorded in the historical operating cycle is introduced to correct and converge the initial boundary, thereby gradually forming a power generation permit surface and unit permit surface that are more in line with the actual operating conditions.

[0110] For turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin, their historical distribution ranges are extracted and cross-validated with the corresponding equipment design operating range and commissioning calibration threshold range. The common overlapping range of the three is taken as the preset boundary range of the corresponding parameter. The preset boundary ranges corresponding to each parameter are combined to form a preset power generation boundary parameter group.

[0111] Subsequently, the permissible ranges for turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin were determined respectively.

[0112] Examples of permissible ranges are: turbine exhaust pressure permissible range of 5.1 kPa to 8.3 kPa, condenser steam side absolute pressure permissible range of 5.4 kPa to 8.8 kPa, vacuum circulating water system temperature difference permissible range of 3.8℃ to 6.6℃, and steam drive branch margin permissible range of 0.12 to 0.46.

[0113] Only when a set of power generation-side state parameters falls within all four of the above-mentioned permissible intervals is the set of state parameters considered to be within the power generation permissible plane.

[0114] Therefore, the power generation permit range is no longer a single parameter threshold, but a multi-constraint allowable range jointly defined by four types of parameters.

[0115] The process for establishing the unit's permission surface is as follows: The establishment of the unit's permissible scope adopts a triple constraint method of "historical stable sample range, safe operating range of the unit, and commissioning calibration threshold range".

[0116] The intelligent control system first reads the comprehensive status parameter set recorded in the historical operating cycle from the database, and extracts the historical values ​​of generator temperature, generator pressure, absorber temperature, absorber pressure and lithium bromide solution concentration.

[0117] The safe operating range of the unit was obtained by reading the factory technical manual, installation and commissioning documents and on-site commissioning records of the lithium bromide absorption turbine. The calibration threshold range was obtained by statistical analysis of stable operating samples under winter heating and summer cooling conditions. Specifically, continuous stable samples under low load, medium load, and high load conditions were used. After removing outliers, the 5th percentile value was taken as the lower limit threshold and the 95th percentile value was taken as the upper limit threshold.

[0118] For the permissible range of the generator, the intelligent control system determines the historical stable range of the generator temperature, the design safe range of the generator temperature, and the calibration range of the generator temperature, and then takes the common overlapping range of the three as the permissible range of the generator temperature; at the same time, it determines the historical stable range of the generator pressure, the design safe range of the generator pressure, and the calibration range of the generator pressure, and then takes the common overlapping range of the three as the permissible range of the generator pressure.

[0119] Only when both the generator temperature and generator pressure are within their respective permissible ranges is the corresponding sample considered to be within the generator's permissible range.

[0120] Taking this embodiment as an example, the permissible temperature range of the generator is determined to be 98.1℃ to 123.7℃, and the permissible pressure range of the generator is determined to be 0.058MPa to 0.083MPa.

[0121] The processing method for the absorber's permitted range is the same as that for the generator's permitted range.

[0122] The intelligent control system first determines the historical stable range, design safety range, and commissioning calibration range of the absorber temperature, and then takes the common overlapping range of the three as the permissible range of the absorber temperature; at the same time, it determines the historical stable range, design safety range, and commissioning calibration range of the absorber pressure, and then takes the common overlapping range of the three as the permissible range of the absorber pressure.

[0123] Only when both the absorber temperature and absorber pressure are within their respective permissible ranges is the corresponding sample considered to be within the absorber's permissible range.

[0124] In this embodiment, the permissible temperature range of the absorber is determined to be 31.2°C to 40.1°C, and the permissible pressure range of the absorber is determined to be 0.78 kPa to 1.33 kPa.

[0125] For the permissible concentration range of lithium bromide solution, the intelligent control system first performs cross-verification based on the historical value of lithium bromide solution concentration, the designed safe range, and the debugging calibration range to obtain the basic concentration range; in this embodiment, the basic concentration range is 57.6wt% to 59.8wt%.

[0126] Based on this, the upper boundary of the basic concentration range is further corrected by combining the historical values ​​of the generator temperature and the absorber temperature: when the generator temperature is higher than 110.0℃, the upper boundary of the basic concentration range is reduced by 0.025wt% for every 1.0℃ increase; when the absorber temperature is lower than 34.0℃, the upper boundary of the basic concentration range is reduced by 0.018wt% for every 1.0℃ decrease; when both conditions occur simultaneously, the corrections are accumulated; when neither condition occurs, the basic concentration range remains unchanged.

[0127] The lower boundary of the baseline concentration range remains unchanged at 57.6 wt% in this embodiment.

[0128] For example, when the historical generator temperature is 114.0℃ and the historical absorber temperature is 33.0℃, the upper limit correction for the concentration is the sum of 0.100wt% and 0.018wt%, i.e., 0.118wt%. The corrected upper limit for the concentration is 59.682wt%, corresponding to an allowable range of 57.6wt% to 59.682wt% for the lithium bromide solution concentration.

[0129] After determining the permissible ranges for the generator, absorber, and lithium bromide solution concentration, the intelligent control system uses "simultaneous satisfaction" as the judgment principle to screen historical samples that are simultaneously located within the permissible ranges for the generator, absorber, and lithium bromide solution concentration. The combined value range formed by the above historical samples within the parameter space of "generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration" is determined as the permissible range of the unit.

[0130] Therefore, the unit's permissible range is not a single temperature range, a single pressure range, or a single concentration range, but a multi-parameter joint permissible domain jointly defined by the three types of permissible ranges.

[0131] After the permission plane is established, the real-time determination process corresponding to this embodiment begins.

[0132] The intelligent control system forms a real-time integrated status parameter set according to the method disclosed in Example 2 within the current sampling period, and compares the integrated status parameter set with the power generation permit surface and the unit permit surface.

[0133] In this embodiment, taking a winter heating determination moment as an example, the turbine exhaust pressure collected during the current sampling period is 6.6 kPa, the condenser steam-side absolute pressure is 6.3 kPa, the vacuum circulating water system inlet temperature is 31.5℃, the vacuum circulating water system outlet temperature is 26.8℃, therefore the vacuum circulating water system temperature difference is 4.7℃, the steam drive branch pressure is 0.36 MPa, the steam drive branch flow rate is 11.4 t / h, and the calculated steam drive branch margin is 0.15; at the same time, the generator temperature is 107.8℃, the generator pressure is 0.069 MPa, the absorber temperature is 35.1℃, the absorber pressure is 0.94 kPa, the lithium bromide solution concentration is 58.8 wt%; the heating network return water temperature is 49.6℃, and the user heating load is 11.2 MW.

[0134] The comparison shows that the power generation side parameters are both located on the power generation permission plane, and the unit side parameters are both located on the unit permission plane. Therefore, the real-time integrated status parameter set meets the dual permission plane requirement.

[0135] At this point, the target operating state is determined based on the parameters on the network side and the user side. Since the return water temperature of the heating network is lower than the preset return water temperature threshold of 52.5℃ and the user heating load value is higher than the preset heating load threshold of 10.8MW, the target operating state is determined to be the winter heating operating state.

[0136] Taking a summer cooling supply determination time as an example, during the current sampling period, the turbine exhaust pressure is 6.8 kPa, the condenser steam-side absolute pressure is 6.5 kPa, the vacuum circulating water system temperature difference is 4.4℃, the steam drive branch pressure is 0.37 MPa, the steam drive branch flow rate is 12.7 t / h, and the corresponding steam drive branch margin is 0.22; the generator temperature is 113.4℃, the generator pressure is 0.074 MPa, the absorber temperature is 35.9℃, the absorber pressure is 1.02 kPa, and the lithium bromide solution concentration is 59.1 wt%; the cooling network return water temperature is 12.8℃, and the user cooling load is 9.4 MW.

[0137] After comparison, both permit conditions are met, and the return water temperature of the cooling network is 12.1℃ higher than the preset cooling return water temperature threshold, and the user cooling load value is 8.9MW higher than the preset cooling load threshold. Therefore, the target operating state is determined to be the summer cooling operating state.

[0138] If any generator-side parameter or unit-side parameter in the real-time integrated status parameter group exceeds the allowable range of the permissible surface, or if the dual permissible surfaces are met but the judgment conditions for winter heating operation and summer cooling operation are not met, the system will maintain the current operating state and will not execute state transition control.

[0139] It should be noted that the preset heating return water temperature threshold, preset cooling return water temperature threshold, preset heating load threshold, and preset cooling load threshold are not arbitrarily set values, but are determined by historical stable operation samples, user demand records, and the equipment's designed power supply capacity.

[0140] The preset heating return water temperature threshold is determined based on the distribution of heating network return water temperature in the stable heating sample of the previous heating season. The preset cooling return water temperature threshold is determined based on the cooling network return water temperature distribution in the stable cooling sample from the previous cooling season. The preset heating load threshold is determined based on the historical demand distribution of users' heating load and the minimum stable heating capacity of the heating network. The preset cooling load threshold is determined based on the historical demand distribution of users' cooling load and the minimum stable cooling capacity of the cooling network.

[0141] When the return water temperature of the heating network is lower than the preset return water temperature threshold and continues to reach the first judgment time, and at the same time the user's heating load value is higher than the preset heating load threshold and continues to reach the first judgment time, the intelligent control system determines the target operating state as the winter heating operating state.

[0142] When the return water temperature of the cooling network is higher than the preset cooling return water temperature threshold and continues to reach the second judgment time, and at the same time the user's cooling load value is higher than the preset cooling load threshold and continues to reach the second judgment time, the intelligent control system determines the target operating state as the summer cooling operating state.

[0143] When both the winter heating operation status determination conditions and the summer cooling operation status determination conditions are met, the intelligent control system compares the excess ratio of the user's heating load value relative to the preset heating load threshold and the excess ratio of the user's cooling load value relative to the preset cooling load threshold, and determines the operation status with the higher excess ratio as the target operation status; when the difference between the two excess ratios is less than the preset arbitration difference, the intelligent control system maintains the current operation status.

[0144] Once the target operating state is determined, it is not allowed to switch back to the target operating state due to temperature or load fluctuations within a single sampling period within the preset holding time.

[0145] By establishing the power generation permitting surface and unit permitting surface through historical samples, the determination of the current operating status no longer relies on a single return water temperature threshold or a single load threshold. Instead, it first undergoes safety boundary screening on the power generation side and unit side, and then combines network side and user side demand parameters to determine the target operating status, thereby significantly improving the reliability of status determination.

[0146] In particular, the temperature-coupled correction of the lithium bromide solution concentration boundary in the unit's permissive surface allows the concentration boundary to automatically tighten under conditions where the generator temperature is too high or the absorber temperature is too low, avoiding the possibility of missing the crystallization risk when judging with a fixed concentration threshold.

[0147] Example 4 Please refer to Figures 1-4 Specifically: In S3, when the target operating state is the winter heating operating state, the migration target of the state transition control process is to establish a heating path from the vacuum circulating water system to the heating network and to switch the lithium bromide unit to the heating operating mode. When the target operating state is summer cooling operation, the migration target of the state transition control process is to establish a steam drive branch to the lithium bromide unit, connect the cooling path of the cooling network, and switch the lithium bromide unit to cooling operation mode.

[0148] In S3, the state transition control process includes, in sequence, a pre-conditioning phase, an isolation phase, a reconfiguration phase, and a convergence phase; The pre-adjustment phase involves pre-load reduction control of the current operating load, pre-connection control of the branch corresponding to the target operating state, and pre-connection control of the transitional support branch. During the isolation phase, the corresponding heat source path and main branch of the current operating state are exited sequentially according to a preset switching order. The reconfiguration phase includes establishing heating and cooling paths corresponding to the target operating state, and performing path correction based on the target flow rate and target pressure difference corresponding to the target operating state. During the convergence phase, the target operating state load is increased according to the preset load ramp rate, and the transition protection branch is gradually withdrawn after the output stability of the target operating state reaches the exit condition of the transition protection branch.

[0149] In this embodiment, the same application scenario as in Embodiments 1 to 3 is still used.

[0150] Example 3 has disclosed the formation method of power generation permit surface, unit permit surface and target operating state. Based on this, this example focuses on disclosing the state transition control process involved in this example, that is: after the target operating state is determined, how to establish the transition target for winter heating operating state and summer cooling operating state respectively, and how the pre-adjustment stage, isolation stage, reconfiguration stage and convergence stage are executed in sequence and finally the state transition is completed.

[0151] In this embodiment, the so-called "migration target" refers to the heat source path reconstruction result and unit operation mode switching result that the system needs to achieve after the target operating state is confirmed; The so-called "pre-adjustment stage" refers to the preparatory stage in which the old state load, the new state branch, and the transition protection branch are pre-controlled before the old operating state is exited. The so-called "isolation phase" refers to the phase in which the heat source path and main branch corresponding to the current operating state are exited according to a predetermined switching sequence; The so-called "reconstruction phase" refers to the phase of establishing the heat source path and pipeline path corresponding to the target operating state, and correcting the new path through the target flow rate and target pressure difference; The so-called "convergence phase" refers to the phase after the new path has been established, in which the target operating load is gradually increased according to the preset load ramp, so that the output enters the stable range and meets the conditions for exiting the transition protection branch.

[0152] "Target flow rate" is a target flow rate value determined under the target operating conditions based on historical stable samples, real-time user demand, and pipeline transportation capacity. "Target pressure difference" is the pressure difference value required at the first station to ensure stable transmission from the first station to the user terminal under the target operating conditions; The "preset load ramp rate" is the percentage of load that can be increased per unit time during the convergence phase of the state transition control process. Its function is to suppress the oscillation of water supply temperature and differential pressure caused by load surge.

[0153] During winter heating operation, the goal of the state transition control process is to establish a heating path from the vacuum circulating water system to the heating network and to switch the lithium bromide absorption chiller to heating operation mode.

[0154] To illustrate the execution process, a typical winter heating relocation event is selected as an example.

[0155] During a certain sampling period, the comprehensive status parameter group showed that the return water temperature of the heating network was 49.8℃, the user heating load was 11.4MW, the inlet water temperature of the vacuum circulating water system was 31.7℃, the outlet water temperature of the vacuum circulating water system was 26.8℃, and the corresponding temperature difference of the vacuum circulating water system was 4.9℃. At the same time, the status parameters on the power generation side and the status parameters on the unit side were both within their respective permissible ranges. Based on this, the intelligent control system determined that the target operating state was the winter heating operating state.

[0156] After entering the pre-adjustment stage, the intelligent control system first executes the pre-load reduction control of the current operating state load, reducing the relevant load of the original operating state at a rate of 2.4% to 2.8% per minute for about 8 minutes; in the same stage, the pre-connection valve on the heating side is adjusted from the initial closed state to about 23% opening, the heat exchange branch of the vacuum circulating water system is pre-opened to about 18% opening, the transition protection branch is pre-opened to about 16% opening, the frequency of the heating main pump is adjusted from 37Hz to 40Hz, and the frequency of the internal solution circulation pump of the lithium bromide absorption unit is increased from 31Hz to 36Hz, so that the internal circulation volume of the unit enters the heating preparation range first.

[0157] The purpose of this stage is not to immediately establish a heating path, but to reduce the old load first, make the heating path conductive, and provide a transitional energy supply basis on the user side, thereby avoiding heating fluctuations caused by subsequent isolation actions.

[0158] After the pre-conditioning phase is completed, the isolation phase begins.

[0159] In this embodiment, the isolation phase adopts a preset switching order of "first exiting the heat source path corresponding to the current operating state, and then exiting the main branch corresponding to the current operating state".

[0160] In practice, the intelligent control system first gradually reduces the opening of the control valve on the original non-heat source path from 61% to 12%, with a maximum adjustment step of no more than 9% per minute, for about 4 minutes; then it reduces the opening of the original main branch valve from 58% to 10%, for about 3 minutes.

[0161] During the isolation phase, the transitional support branch remained connected, the water supply temperature at the primary heating station increased from 57.1℃ to 59.3℃, the return water temperature stabilized from 48.9℃ to 49.6℃, and the fluctuation of the heating flow rate on the user side was controlled within ±3.8%.

[0162] By adopting this isolation sequence of "heat source first, then main branch", the old path is systematically separated, avoiding the formation of impact coupling between the old path and the new path under high load conditions.

[0163] After the isolation phase ends, the reconstruction phase begins.

[0164] During winter heating operation, the core of the reconstruction phase is to establish a heating path from the vacuum circulating water system to the heating network and to correct the new path based on the target flow rate and target pressure difference.

[0165] In this embodiment, the target flow rate is set to 3240m³. 3 / h, the target differential pressure is set to 96kPa.

[0166] The intelligent control system first increases the opening degree of the heat exchange branch valve of the vacuum circulating water system from 18% to 68%, and increases the frequency of the main heating pump from 40Hz to 43Hz, so that the vacuum circulating water system and the heating network form the main heating path. Then, the path is corrected every 60 seconds. If the deviation between the measured flow rate and the target flow rate is greater than 5%, the main pump frequency is adjusted first, and the frequency adjustment in a single instance shall not exceed 1.5Hz. If the deviation between the measured pressure difference and the target pressure difference is greater than 4kPa, the opening degree of the main branch regulating valve is adjusted first, and the opening degree adjustment in a single instance shall not exceed 6%.

[0167] During a typical reconfiguration cycle, the flow rate of the primary heating station increases from 2910 m³ / h. 3 / h gradually increased to 3210m 3 / h, the pressure difference at the first station increased from 88.4kPa to 95.1kPa, taking approximately 12 minutes.

[0168] In this way, the establishment of a new path does not involve opening all valves at once, but rather gradually approaches the target operating condition under the constraints of known target flow rate and target pressure difference, thus making the establishment process of the heating path correctable.

[0169] After the reconstruction phase ends, the convergence phase begins. The purpose of the convergence phase is to move the newly established heating path from the "conductable state" to the "stable output state".

[0170] In this embodiment, during the convergence phase, a preset load ramp of 3.0% / min is used to increase the target operating load, so that the water supply temperature of the first heating station gradually increases from 59.3℃ to 61.8℃, the return water temperature stabilizes at 50.6℃, the pressure difference of the first station stabilizes at 96.3kPa, and the heat output on the user side stabilizes in the range of 11.1MW to 11.4MW.

[0171] The transitional backup branch will not be immediately disconnected after the reconstruction is completed, but will remain connected during the convergence phase until the following disconnection conditions are met simultaneously: the fluctuation range of the supply water temperature of the heating station is no greater than 1.0℃, the fluctuation range of the return water temperature is no greater than 1.2℃, the continuous operation time is no less than 18 minutes, and the flow deviation of the main heating branch is no greater than ±4.5%.

[0172] After continuously meeting the above conditions, the intelligent control system will gradually reduce the opening of the transition protection branch from 16% to 0, completing the state transition control process under the winter heating operation state.

[0173] During summer cooling operation, the goal of the state transition control process is to establish a cooling path from the steam-driven branch to the lithium bromide absorption chiller and connect it to the cooling network, and to switch the lithium bromide absorption chiller to cooling operation mode. A typical summer cooling transition event is selected as an example.

[0174] During a certain sampling period, the return water temperature of the cooling network was 12.9℃, the user cooling load was 9.6MW, the steam drive branch pressure was 0.37MPa, the steam drive branch flow rate was 12.8t / h, the generator temperature was 113.1℃, and the absorber temperature was 35.8℃. The results of the dual permissible surface comparison met the allowable range. Therefore, the intelligent control system determined the target operating state to be the summer cooling operation state.

[0175] After entering the pre-adjustment stage, the heat output load under the current non-cooling operation state decreases at a rate of 2.1% to 2.6% per minute, the frequency of the cooling main pump increases from 29Hz to 34Hz, the pre-regulating valve of the steam drive branch is pre-opened to 26%, and the transition protection branch is pre-opened to 22%, lasting for about 10 minutes.

[0176] At the end of this phase, the water supply temperature at the first cooling station dropped from 13.1℃ to 10.2℃, and the user side had obtained a stable transitional cooling capacity.

[0177] During the isolation phase, first disconnect from the original non-cooling / heating source path, and then disconnect from the original main branch path.

[0178] Since the cooling system is more sensitive to changes in the supply water temperature, this embodiment limits the valve adjustment rate during the isolation phase to no more than 8% of the opening change per minute, and the entire phase lasts for about 8 minutes.

[0179] During the isolation phase, the maximum fluctuation of the water supply temperature at the primary cooling station is 0.7℃, and the deviation of the cooling flow rate on the user side is controlled within ±3.4%. The transitional backup branch continues to guarantee the cooling capacity on the user side.

[0180] After entering the reconfiguration phase, the intelligent control system opens the steam drive branch to the drive valve group of the lithium bromide absorption chiller and connects to the cooling pipeline network to establish a cooling path.

[0181] The target flow rate for this stage is set at 2760 m³ / h. 3 / h, with a target differential pressure of 84kPa. The correction method is the same as that for winter heating operation. The flow rate deviation and differential pressure deviation are calculated every 60s. When the flow rate deviation is greater than 4.8%, the chilled water pump frequency is adjusted first. When the differential pressure deviation is greater than 3.5kPa, the opening of the cooling branch valve is adjusted first.

[0182] After approximately 13 minutes of calibration, the flow rate of the primary cooling station decreased from 2430 m³ / h. 3 / h increased to 2740m 3 / h, the pressure difference at the first station increased from 77.2kPa to 83.4kPa, and the cooling path reached a stable state.

[0183] It then enters the convergence phase.

[0184] During the convergence phase, the cooling load is increased at a preset load ramp rate of 2.8% / min, causing the water supply temperature of the first cooling station to gradually decrease from 10.2℃ to 6.9℃, the return water temperature to gradually stabilize from 13.2℃ to 12.0℃, and the cooling load on the user side to stabilize in the range of 9.2MW to 9.5MW.

[0185] The transitional backup branch remains connected during this stage until the following exit conditions are met simultaneously: the fluctuation range of the supply water temperature at the primary cooling station is no greater than 0.9℃, the fluctuation range of the return water temperature is no greater than 1.1℃, the continuous operating time is no less than 20 minutes, and the flow deviation of the main cooling branch is no greater than ±4.0%. After the conditions are met, the opening degree of the transitional backup branch gradually decreases from 22% to 0, and the state transition control process under the summer cooling operation state is completed.

[0186] To verify the implementation effect of this embodiment, under the same system conditions as Embodiments 1 to 3, 10 consecutive winter heating state migration events and 10 consecutive summer cooling state migration events were selected for statistical analysis.

[0187] When using the method of this embodiment, the average completion time for winter heating state migration is 42.7 min, and the average completion time for summer cooling state migration is 45.9 min. In the 20 migration events, there was no interruption of heating or cooling supply on the user side. The maximum fluctuation of the water supply temperature at the first heating station in winter heating events was 0.9℃, and the maximum fluctuation of the water supply temperature at the first cooling station in summer cooling events was 0.8℃. Within 10 min after the end of the reconstruction phase, the average target flow deviation for winter heating events was 3.2%, and the average target differential pressure deviation was 2.8 kPa. The average target flow deviation for summer cooling events was 3.1%, and the average target differential pressure deviation was 2.7 kPa. In all 20 events, there was no situation where migration freezing was directly triggered due to instability during the migration process.

[0188] The above results demonstrate that this embodiment does not merely provide a general description of the "switching process," but rather transforms the state transition process between winter heating operation and summer cooling operation into an executable, verifiable, and verifiable engineering control process through a continuous control chain of "target operating state classification, clear migration target, sequential execution of four stages, target flow and target pressure difference correction, and conditional exit of transitional protection branches."

[0189] The beneficial effects of this embodiment are reflected in the following aspects.

[0190] First, once the target operating state is determined, different operating states do not use the same set of fuzzy switching actions. Instead, different migration targets are established according to the winter heating operating state and the summer cooling operating state, so as to ensure that the heat source path and the unit operating mode have a clear correspondence in winter and summer.

[0191] Secondly, the pre-conditioning stage, isolation stage, reconstruction stage, and convergence stage are not simply stage names, but rather four different control functions: load preprocessing, old path stripping, new path establishment, and new state stabilization, respectively. This transforms the state transition control process from abrupt switching to sequential and correctable switching.

[0192] Furthermore, during the reconfiguration phase, target flow rate and target differential pressure are introduced as correction criteria, so that path establishment no longer relies on empirical valve opening, but can perform closed-loop adjustment based on real-time deviations.

[0193] Finally, by setting clear exit conditions for the transitional protection branch during the convergence phase, the timing of the transitional protection branch's exit is transformed from manual experience-based judgment to quantifiable judgment, thereby further ensuring continuous power supply to users and stable output in the new operating state.

[0194] Example 5 Please refer to Figures 1-4 Specifically: In S4, the transition protection branch is independently set up in the main heat source path and main circulation branch of the power plant waste heat winter and summer combined supply system; Transitional support routes include energy storage routes and bypass routes; The continuous power supply control strategy includes taking over the transitional backup branch before the isolation phase begins, continuously supplying power to users through the transitional backup branch during the isolation and reconstruction phases, and exiting the transitional backup branch after the preset takeover exit conditions are met during the convergence phase. The preset takeover exit conditions include continuous power supply on the user side, stable output of the target operating status, and the target flow rate and target pressure difference meeting the preset allowable deviation range.

[0195] In S4, the margin of the unit's permissible surface is defined as the minimum deviation between the unit-side state parameters in the integrated state parameter set and the boundary of the allowable interval of the unit's permissible surface. The margin of the power generation permit surface is defined as the minimum deviation between the power generation side state parameters in the integrated state parameter set and the allowable interval boundary of the power generation permit surface. The margin of the unit's permissible surface is defined as follows: for each parameter in the unit-side state parameter group, calculate the relative deviation of its current value from the boundary of the permissible interval of the unit's permissible surface, and take the minimum value among all relative deviations; where the relative deviation is the ratio of the distance from the current value of the parameter to the boundary of the permissible interval to the width of the permissible interval; The margin of the power generation permit surface is defined as follows: for each parameter in the power generation side state parameter group, calculate the relative deviation of its current value from the boundary of the allowable interval of the power generation permit surface, and take the minimum value among all relative deviations; where the relative deviation is the ratio of the distance from the current value of the parameter to the boundary of the allowable interval to the width of the allowable interval; Intervention levels are determined based on the correspondence between the unit permit area and the power generation permit area margin and the first intervention threshold, the second intervention threshold, the third intervention threshold and the fourth intervention threshold, respectively; Pre-dilution control is executed when the pre-dilution level is reached. When the bypass reflux level is reached, bypass reflux control is executed; When the inclination rate reduction level is reached, inclination rate reduction control is implemented. When the migration freeze level is reached, state migration freeze control is executed.

[0196] In S4, the state transition is considered complete when the output stability of the target operating state meets the preset conditions. The preset conditions include that the fluctuation range of the supply water temperature of the heating network or the supply water temperature of the cooling network is within a preset range, and the fluctuation range of the return water temperature of the heating network or the return water temperature of the cooling network is within a preset range, and the continuous operation time reaches a preset duration. When the output stability of the target operating state does not meet the preset conditions, the state transition control process is kept in the convergence phase, and the transition protection branch is kept connected. When the migration freeze level is reached during the convergence phase, state migration freeze control is executed. After the state transition is determined, the comprehensive state parameter group, target operating state, state transition duration, intervention level, and takeover duration for the current operating cycle are stored in the database of the intelligent control system as records for subsequent historical operating cycles.

[0197] In this embodiment, the same application scenario as in Embodiments 1 to 4 is still adopted. In this embodiment, the transition protection branch is independently set outside the main heat source path and main circulation branch of the power plant waste heat winter and summer combined supply system, and is directly connected to the user branch.

[0198] Transitional support routes include energy storage routes and bypass routes.

[0199] The capacity of the energy storage branch is not a fixed value, but is determined based on the design load of the key user, the allowable transition time, and the maximum compensation requirements during the state transition control process. The rated bypass capacity of the bypass branch is determined based on the rated flow of the main circulation branch, the minimum continuous energy supply flow of the key user, and the allowable differential pressure fluctuation range during the convergence phase.

[0200] Under normal circumstances, the capacity of the energy storage branch should at least meet the continuous energy supply needs of critical users during the isolation and reconfiguration phases, and the rated bypass capacity of the bypass branch should not be lower than the upper limit of the continuous energy supply flow of critical users.

[0201] In this embodiment, based on the maximum transition load of critical users, a 30-minute transition guarantee duration, and system commissioning results, the effective energy storage capacity of the energy storage branch is determined to be 5.8 MWh, and the rated cycle capacity is 420 m³ / s. 3 / h; The rated bypass capacity of the bypass branch is determined to be 310 m based on the minimum continuous power supply flow of key users and the main branch correction requirements. 3 / h.

[0202] The inlet of the energy storage branch is connected to the main return water pipe of the first station, and the outlet is connected to the user's dedicated branch. One end of the bypass branch is connected to the main water supply pipe of the first station, and the other end is connected to the user's pre-distribution main pipe, thus forming an independent protection loop that bypasses the main heat source path and the main circulation branch.

[0203] The intelligent control system controls the transition protection branch in a fixed sequence: 120 seconds before the isolation phase begins, the energy storage branch is connected first, followed by the bypass branch; both are kept connected during the isolation and reconfiguration phases; during the convergence phase, the system gradually exits in the order of "reducing the bypass branch first, then the energy storage branch" only when the preset takeover exit conditions are met.

[0204] The reason for adopting this order is that the withdrawal of bypass branches will directly affect flow fluctuations, while the withdrawal of energy storage branches will more directly affect the continuity of energy supply at the user end. Therefore, the buffers on pressure and flow should be released first, and then the reserve supply of heat or cold should be released.

[0205] The continuous supply control strategy is implemented as follows.

[0206] Before the state transition control process enters the isolation phase, the intelligent control system first reads the real-time load value on the user side and the load change rate in the previous fusion cycle to determine the initial access ratio of the transition protection branch.

[0207] In a typical switching event during winter heating operation, when the user heating load is 11.3MW and the load change rates in the last two fusion cycles are 2.1% and 1.8% respectively, the intelligent control system sets the opening of the energy storage branch valve to 21%, the opening of the bypass branch valve to 16%, and increases the frequency of the independent circulation pump to 39Hz, so that the user branch first obtains transitional heat compensation. During the isolation and reconfiguration phases, the intelligent control system calculates the user-side heating flow deviation and heating temperature difference deviation every 60 seconds. When the heating flow deviation is greater than ±4.5%, the bypass branch valve opening is adjusted first. When the heating temperature difference deviation is greater than ±1.3℃, the energy storage branch circulation pump frequency is adjusted first.

[0208] In a typical switching event during summer cooling operation, when the user's cooling load is 9.5MW and the load change rate in the last two integration cycles is 2.4% and 2.0% respectively, the intelligent control system sets the opening of the energy storage branch valve to 24%, the opening of the bypass branch valve to 18%, and increases the frequency of the independent circulation pump to 41Hz, continuously outputting cooling capacity to the user side during the isolation and reconfiguration phases. During this phase, the cooling flow deviation and cooling temperature difference deviation are calculated every 60s. When the cooling flow deviation is greater than ±4.0%, the opening of the bypass branch valve is adjusted, and when the cooling temperature difference deviation is greater than ±1.1℃, the frequency of the energy storage branch circulation pump is adjusted.

[0209] In this way, the transitional backup branch is not merely "connected," but continuously adjusted according to the real-time needs and deviation changes of the user side, thereby ensuring that the user does not experience power interruption during the period of old path exit and new path establishment.

[0210] The margins of the unit's permissible surface and the margins of the power generation permissible surface are defined using a relative deviation method.

[0211] For each parameter in the unit-side state parameter group, if the current value is within the corresponding permissible interval, calculate the distance from the current value to the lower boundary of the permissible interval and the distance to the upper boundary of the permissible interval respectively, take the smaller of the two as the boundary distance, and then divide the boundary distance by the interval width of the corresponding permissible interval to obtain the relative deviation of the parameter; the same calculation method is used for each parameter in the generator-side state parameter group.

[0212] Subsequently, the minimum value among all relative deviations in the unit-side state parameter group is taken as the margin of the unit's permissible surface; the minimum value among all relative deviations in the generator-side state parameter group is taken as the margin of the generator's permissible surface.

[0213] If the current value of a parameter has exceeded the corresponding permissible range, the relative deviation of the parameter is directly recorded as a negative value, and this negative value is included in the margin determination.

[0214] In this embodiment, a set of real-time samples during a winter heating migration event shows: the generator temperature is 109.8℃, the generator's permissible range is 98.1℃ to 123.7℃, then its distances to the upper and lower boundaries are 11.7℃ and 13.9℃ respectively, the range width is 25.6℃, and the relative deviation is taken as 11.7 / 25.6, approximately 0.457; the absorber pressure is 0.92kPa, the absorber's permissible range is 0.78kPa to 1.33kPa, then the relative deviation is approximately 0.255; the lithium bromide solution concentration is 58.9wt%, the corrected permissible concentration range is 57.6wt% to 59.71wt%, the relative deviation is approximately 0.384, therefore, the margin of the unit's permissible surface in this cycle is taken as 0.255.

[0215] The reason for using relative deviation instead of absolute deviation is that different parameters have significantly different dimensions and interval widths. Only the normalized relative deviation can reflect the degree to which the parameters approximate the safety boundary on the same scale.

[0216] After completing the margin calculation, the intelligent control system classifies the intervention level based on the correspondence between the unit's permissible margin and the power generation permissible margin and the four-level intervention threshold. In this embodiment, the first intervention threshold is set to 0.12, the second intervention threshold is set to 0.08, the third intervention threshold is set to 0.05, and the fourth intervention threshold is set to 0.02.

[0217] When the margin of the unit's permissible surface or the margin of the power generation permissible surface is between 0.08 and 0.12, it enters the pre-dilution stage. The intelligent control system opens the dilution valve group and maintains the replenishment flow rate at 8% to 12% of the rated value. At the same time, the frequency of the solution circulation pump is increased by 2Hz to 4Hz to reduce local concentration and crystallization risk. When the margin is between 0.05 and 0.08, it enters the bypass reflux level. The intelligent control system opens the bypass reflux valve to 15% to 35% opening, so that a controlled reflux is formed between the high-pressure side and the low-pressure side of the unit, which alleviates the local pressure peak. When the margin is between 0.02 and 0.05, the load reduction level with limited slope is entered. The intelligent control system will reduce the load increase slope during the convergence phase from the original setting of 2.8% / min to 3.0% / min to 1.4% / min to 1.8% / min to slow down the speed at which the system continues to approach the boundary. When the margin is below 0.02, the system enters the migration freeze level. The intelligent control system immediately stops the load increase action in the current convergence phase, locks the current valve opening and main pump frequency, and maintains the transition protection branch connection to ensure continuous power supply to users.

[0218] Taking a summer cooling migration event as an example, when the generator temperature rises to 124.3℃ in the 12th minute of the convergence phase, the margin of the unit's permissible surface drops to 0.018. The system immediately switches from the limited slope descent level to the migration freeze level, stops increasing the cooling load, and increases the bypass branch opening from 18% to 26% and the energy storage branch valve from 24% to 29%. The freeze lasts for about 6 minutes. After the margin of the unit's permissible surface recovers to 0.054, the system returns to the limited slope descent level and continues to execute the convergence phase.

[0219] The output stability of the target operating state is determined using a joint determination method, rather than a single temperature determination method.

[0220] Under winter heating operation conditions, the preset conditions include: the fluctuation range of the heating network supply water temperature is no greater than 1.0℃, the fluctuation range of the heating network return water temperature is no greater than 1.2℃, the continuous operation time is no less than 18 minutes, the target flow deviation is no greater than ±4.5%, and the target pressure difference deviation is no greater than ±4.0 kPa. Under summer cooling operation conditions, the preset conditions include: the fluctuation range of the cooling network supply water temperature is no greater than 0.9℃, the fluctuation range of the cooling network return water temperature is no greater than 1.1℃, the continuous operation time is no less than 20 minutes, the target flow deviation is no greater than ±4.0%, and the target pressure difference deviation is no greater than ±3.5 kPa.

[0221] The intelligent control system determines that the state transition is complete only when the above conditions are met continuously.

[0222] If the output stability does not meet the preset conditions, the state transition control process will remain in the convergence phase and the transition protection branch will be kept connected, and fine-tuning of flow rate, differential pressure and valve opening will continue. If the transition freeze level is reached again during the convergence phase, the load will be stopped immediately and state transition freeze control will be executed.

[0223] In a winter heating relocation event, the supply water temperature of the primary heating station fluctuated by 0.8℃ from 17 minutes to 34 minutes, the return water temperature fluctuated by 1.0℃, the target flow rate deviation was 3.2%, and the target differential pressure deviation was 2.7 kPa. Therefore, the relocation was considered complete after meeting these conditions for 18 consecutive minutes. In a summer cooling relocation event, the supply water temperature of the primary cooling station fluctuated by 0.7℃ from 19 minutes to 41 minutes, the return water temperature fluctuated by 0.9℃, the target flow rate deviation was 3.1%, and the target differential pressure deviation was 2.8 kPa. Therefore, the relocation was considered complete after meeting these conditions for 20 consecutive minutes.

[0224] After determining that the state transition is complete, the intelligent control system writes the comprehensive state parameter group, target operating state, state transition duration, intervention level, and takeover duration for the current operating cycle into the database as a record for subsequent historical operating cycles.

[0225] To ensure consistency in subsequent calls, each historical operating cycle record in this embodiment includes a timestamp field, an operating season field, a target operating status field, a power generation permit margin field, a unit permit margin field, an intervention level field, a total state transition duration field, a total transition guarantee branch connection duration field, and an output stability judgment result field.

[0226] Therefore, the records after the state transition are not ordinary operation logs, but directly serve as the data foundation for subsequent permission surface correction, threshold adjustment, and operation optimization. In 12 consecutive winter heating state transition events and 12 summer cooling state transition events, the average connection time of the transition backup branch was 26.4 min and 28.7 min, respectively. The continuity of heating and cooling on the user side remained intact. The maximum fluctuation of the water supply temperature at the heating station in the winter heating event was 0.9℃, and the maximum fluctuation of the water supply temperature at the cooling station in the summer cooling event was 0.8℃. In 24 transition events, the pre-dilution level was triggered 5 times, the bypass return level was triggered 3 times, the slope reduction level was triggered 2 times, and the transition freeze level was triggered 1 time. Moreover, the freeze event did not cause power outage for users under the condition that the transition backup branch remained connected.

[0227] The above results demonstrate that the technical solution constituted in this embodiment is not a single set of protection actions, but rather integrates the transition protection branch, continuous supply control strategy, permissible margin, intervention level, output stability determination, and historical record formation into a complete closed-loop control process. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for combined winter and summer power generation of waste heat from power plants based on lithium bromide generating units, characterized in that, Includes the following steps: S1. By setting up collection points on the power plant waste heat cogeneration system, real-time data collection of operating status is carried out, and the data of operating status is transmitted to the intelligent control system. The data of operating status is combined in the intelligent control system to obtain a comprehensive status parameter group. S2. The power generation permitting surface is determined based on the turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin. The unit permitting surface is determined based on the generator temperature, generator pressure, absorber temperature, absorber pressure, and lithium bromide solution concentration. The comprehensive state parameter set is compared with the power generation permitting surface and the unit permitting surface. When the comprehensive state parameter set is simultaneously at both the power generation permitting surface and the unit permitting surface, the target operating state is determined. When the comprehensive state parameter set is not simultaneously at both the power generation permitting surface and the unit permitting surface, the current operating state is maintained. S3. After determining the target operating state, execute the state transition control process, which includes the pre-adjustment stage, isolation stage, reconstruction stage and convergence stage in sequence. S4. During the state transition control process, a continuous supply guarantee control strategy and an active safety intervention strategy are executed. The continuous supply guarantee control strategy maintains the continuous power supply to users by connecting the transition guarantee branch in the power plant waste heat cogeneration system during the isolation and reconfiguration phases. The active safety intervention strategy divides the intervention levels based on the unit's permissible surface and the margin of the power generation permissible surface. The intervention levels include pre-dilution level, bypass return level, slope limiting load reduction level, and migration freeze level, and corresponding control is executed according to the corresponding intervention level. When the output stability of the target operating state meets the preset conditions, the state transition is determined to be complete.

2. The method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 1, characterized in that, In S1, the power plant waste heat winter and summer combined supply system includes a vacuum circulating water system, a steam drive branch, a lithium bromide absorption unit, a heating network, a cooling network, and an intelligent control system. By setting up several collection points on the power plant's waste heat winter and summer combined supply system and installing collection equipment at these points, the operating status data of the lithium bromide unit is collected in real time, and the operating status data is transmitted to the intelligent control system via a wireless transmission network. The operating status data includes turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system inlet water temperature, vacuum circulating water system outlet water temperature, steam drive branch pressure, steam drive branch flow rate, generator temperature, generator pressure, absorber temperature, absorber pressure, lithium bromide solution concentration, heating network supply and return water temperatures, cooling network supply and return water temperatures, user heating load value, and user cooling load value. The operating status data is processed for time synchronization and unit unification to obtain a standardized dataset. The standardized dataset is then classified to obtain the power generation side status parameter group, the unit side status parameter group, the network side status parameter group, and the user side status parameter group. These are then combined in a preset order to establish a comprehensive status parameter group for the combined power supply system. The integrated state parameter set is then stored in the database of the intelligent control system in chronological order.

3. The method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 2, characterized in that, In S2, the intelligent control system reads the comprehensive state parameter group recorded in the historical operating cycle from the database, and extracts the historical values ​​of turbine exhaust pressure, condenser steam side absolute pressure, vacuum circulating water system temperature difference, steam drive branch pressure and steam drive branch flow from the comprehensive state parameter group. The historical value of the steam-driven branch pressure is calculated by comparing it with the preset minimum driving pressure threshold, and the historical value of the steam-driven branch flow rate is calculated by comparing it with the preset minimum driving flow rate threshold. The smaller of the two differences is taken as the historical value of the steam-driven branch margin. Then, by combining the historical values ​​of turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin with the equipment design operating range and commissioning calibration threshold, the preset power generation boundary parameter set is determined. Based on the preset power generation boundary parameter set, the permissible range of turbine exhaust pressure, the permissible range of condenser steam-side absolute pressure, the permissible range of vacuum circulating water system temperature difference, and the permissible range of steam drive branch margin are determined respectively. The range of values ​​that simultaneously satisfy the permissible range of turbine exhaust pressure, condenser steam-side absolute pressure, vacuum circulating water system temperature difference, and steam drive branch margin is determined as the power generation permissible surface.

4. The method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 3, characterized in that, In S2, the intelligent control system reads the comprehensive status parameter set recorded in the historical operating cycle from the database, and extracts the historical values ​​of generator temperature, generator pressure, absorber temperature, absorber pressure and lithium bromide solution concentration from the comprehensive status parameter set. The historical values ​​of generator temperature and generator pressure, combined with the safe operating range of the unit and the commissioning and calibration thresholds, determine the permissible range of the generator; The absorber's permissible range is determined by combining historical values ​​of absorber temperature and absorber pressure with the unit's safe operating range and commissioning calibration thresholds. Based on historical values ​​of lithium bromide solution concentration, combined with historical values ​​of generator temperature and absorber temperature, the lithium bromide solution concentration boundary is corrected to determine the permissible range of lithium bromide solution concentration. The range of values ​​corresponding to the generator's permissible range, the absorber's permissible range, and the lithium bromide solution concentration permissible range are then determined as the unit's permissible range.

5. The method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 1, characterized in that, In S2, the power generation permit surface and the unit permit surface are compared with the comprehensive status parameter set acquired in real time. When the generation-side state parameter in the integrated state parameter group is located at the generation permitting surface and the unit-side state parameter is located at the unit permitting surface, the target operating state is determined based on the network-side state parameter and the user-side state parameter in the integrated state parameter group. The target operating status includes winter heating operating status and summer cooling operating status; When the return water temperature of the heating network is lower than the preset return water temperature threshold and the user's heating load value is higher than the preset heating load threshold, the target operating state is determined to be the winter heating operating state. When the return water temperature of the cooling network is higher than the preset cooling return water temperature threshold and the user's cooling load value is higher than the preset cooling load threshold, the target operating state is determined to be the summer cooling operating state. When the comprehensive status parameter group does not meet the judgment conditions for winter heating operation status and summer cooling operation status, the current operation status shall be maintained.

6. The method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 5, characterized in that, In S3, when the target operating state is the winter heating operating state, the migration target of the state transition control process is to establish a heating path from the vacuum circulating water system to the heating network and to switch the lithium bromide unit to the heating operation mode. When the target operating state is summer cooling operation, the migration target of the state transition control process is to establish a steam drive branch to the lithium bromide unit, connect the cooling path of the cooling network, and switch the lithium bromide unit to cooling operation mode.

7. A method for combined winter and summer power generation of waste heat from a power plant based on a lithium bromide unit according to claim 6, characterized in that, In S3, the state transition control process sequentially includes a pre-adjustment phase, an isolation phase, a reconstruction phase, and a convergence phase; The pre-adjustment phase involves pre-load reduction control of the current operating load, pre-connection control of the branch corresponding to the target operating state, and pre-connection control of the transitional support branch. The isolation phase involves sequentially exiting the heat source path and main branch corresponding to the current operating state according to a preset switching order; The reconfiguration phase includes establishing heating and cooling paths corresponding to the target operating state, and performing path correction based on the target flow rate and target pressure difference corresponding to the target operating state. The convergence phase increases the target operating state load according to a preset load ramp, and controls the transition protection branch to gradually withdraw after the output stability of the target operating state reaches the exit condition of the transition protection branch.

8. A method for combined winter and summer power generation of waste heat from a power plant based on a lithium bromide unit according to claim 7, characterized in that, In S4, the transition protection branch is independently set in the main heat source path and main circulation branch of the power plant waste heat winter and summer combined supply system; The transitional support branch includes energy storage branch and bypass branch; The continuous power supply control strategy includes taking over the transitional guarantee branch before the isolation phase begins, continuously supplying power to users through the transitional guarantee branch during the isolation and reconstruction phases, and exiting the transitional guarantee branch after the preset takeover exit conditions are met during the convergence phase. The preset takeover exit conditions include continuous power supply on the user side, stable output of the target operating state, and the target flow rate and target pressure difference meeting the preset allowable deviation range.

9. A method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 8, characterized in that, In S4, the margin of the unit's permissible surface is defined as the minimum deviation between the unit-side state parameters in the integrated state parameter set and the boundary of the allowable interval of the unit's permissible surface. The margin of the power generation permit surface is defined as the minimum deviation between the power generation side state parameters in the integrated state parameter set and the allowable interval boundary of the power generation permit surface. Intervention levels are determined based on the correspondence between the unit permit area and the power generation permit area margin and the first intervention threshold, the second intervention threshold, the third intervention threshold and the fourth intervention threshold, respectively; Pre-dilution control is executed when the pre-dilution level is reached. When the bypass reflux level is reached, bypass reflux control is executed; When the inclination rate reduction level is reached, inclination rate reduction control is implemented. When the migration freeze level is reached, state migration freeze control is executed.

10. A method for combined winter and summer power supply of waste heat from a power plant based on a lithium bromide unit according to claim 8, characterized in that, In S4, the state transition is considered complete when the output stability of the target operating state meets the preset conditions. The preset conditions include that the fluctuation range of the heating network supply water temperature and the cooling network supply water temperature are within a preset range, and the fluctuation range of the heating network return water temperature or the cooling network return water temperature is within a preset range, and the continuous operation time reaches a preset duration. When the output stability of the target operating state does not meet the preset conditions, the state transition control process is kept in the convergence phase, and the transition protection branch is kept connected. When the migration freeze level is reached during the convergence phase, state migration freeze control is executed. After the state transition is determined, the comprehensive state parameter group, target operating state, state transition duration, intervention level, and takeover duration for the current operating cycle are stored in the database of the intelligent control system as records for subsequent historical operating cycles.

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