A heat and power decoupling system and method for a combined heat and power unit

Abstract

The present application belongs to the technical field of combined heat and power generation, and discloses a heat and power decoupling system and method for a combined heat and power unit. The unit operation parameters, external energy market data and external environment data of the combined heat and power unit are collected, the heat and power load supply and demand deviation value, external demand fluctuation rate and unit adjustable capacity value are comprehensively determined, and a heat and power dynamic coupling degree index is constructed accordingly. The current heat and power coupling state of the unit can be quantitatively evaluated from multiple dimensions of supply and demand deviation, external impact and unit regulation capacity, avoiding relying on a single parameter or fixed threshold for judgment, and improving the accuracy of heat and power coupling identification. When the heat and power dynamic coupling degree index meets the preset triggering condition, the key mismatch link is identified in combination with the heat and power load supply and demand deviation value, external demand fluctuation rate and unit adjustable capacity value, which is beneficial to distinguishing different imbalance reasons such as insufficient static regulation capacity of the unit and external demand dynamic impact exceeding the response rate, and improving the pertinence of decoupling control.

Description

Technical Field

[0001] This invention belongs to the field of combined heat and power technology, specifically relating to a thermoelectric decoupling system and method for a combined heat and power unit. Background Technology

[0002] Combined heat and power (CHP) units can simultaneously generate electricity and supply heat to users using steam extracted from a steam turbine. They are characterized by high energy efficiency and stable power supply, and are widely used in centralized heating and grid peak-shaving scenarios. However, due to the limitations of the steam turbine's thermodynamic cycle characteristics, there is a strong correlation between the unit's heat extraction steam volume, electrical load, main steam flow rate, and low-pressure cylinder steam inlet volume. When the heating load changes, the unit's power generation output typically changes accordingly, resulting in an operational constraint where power generation is determined by heat demand or heat generation is determined by electricity demand.

[0003] With the continuous increase in installed capacity of new energy sources such as wind power and photovoltaics, the power grid places higher demands on the peak-shaving and frequency regulation capabilities of combined heat and power (CHP) units. Meanwhile, user-side heat load is also affected by factors such as ambient temperature, wind speed, return water temperature of the heating network, and heat consumption patterns, exhibiting significant time-varying and fluctuating characteristics. When the power grid load command and heating demand change simultaneously, CHP units are prone to mismatches between heating capacity and heat load demand, insufficient adjustment space for power generation output, or inability of the unit's dynamic response rate to meet changes in external demand, thereby exacerbating the coupling contradictions between the heat and electricity production processes.

[0004] Existing thermoelectric decoupling technologies typically expand the unit's operating range by configuring thermal storage devices, low-pressure cylinder steam inlet regulating devices, or other auxiliary regulating equipment. However, in actual control processes, a single operating parameter or fixed threshold is often used to determine whether a thermoelectric imbalance has occurred. This approach struggles to comprehensively consider the supply and demand deviation of thermoelectric loads, fluctuations in external demand, and the unit's current adjustable capacity. Consequently, it cannot accurately distinguish whether thermoelectric coupling is caused by insufficient static regulating capacity of the unit or by the rate of change in external demand exceeding the unit's dynamic response capability, resulting in a lack of targeted decoupling measures.

[0005] Furthermore, existing technologies typically employ fixed lookup tables or simple logical judgments when determining decoupling strategies. This makes it difficult to adaptively select matching thermal storage system charging / discharging power and low-pressure cylinder steam flow regulation schemes based on the supply-demand deviation and demand fluctuation characteristics of thermal and power loads under different operating conditions. Some schemes only provide macroscopic power regulation targets, failing to incorporate actual operating parameters such as the specific heat capacity of the thermal storage medium, set temperature difference, and total main steam flow rate. This hinders the conversion of regulation targets into control quantities that can be directly identified by the underlying actuators, such as the flow rate of the thermal storage system's variable frequency pump and the opening degree of the low-pressure cylinder regulating valve, which can easily lead to control command execution deviations or response delays. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing cogeneration units in accurately identifying the key causes of heat and power supply-demand imbalance, and to provide a heat and power decoupling system and method for cogeneration units.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application proposes a method for thermoelectric decoupling of a combined heat and power (CHP) unit, comprising the following steps: Collect unit operating parameters, external energy market data, and external environmental data for combined heat and power units; Based on the collected data, determine the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value; and determine the thermal power dynamic coupling degree index based on the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value. When the thermoelectric dynamic coupling degree index meets the preset triggering conditions, key mismatch links are identified based on the thermoelectric load supply and demand deviation value, external demand volatility and unit adjustable capacity value, and corresponding electric and heat demand deviation characteristics are generated. The characteristics of the electrothermal demand deviation are matched with the preset decoupling strategies in the preset decoupling strategy library to determine the target thermo-electric decoupling strategy. Based on the target thermoelectric decoupling strategy, the target adjustment parameters of the thermal storage system and the target adjustment parameters of the low-pressure cylinder are determined, and thermoelectric decoupling control commands are generated and sent to the thermal storage system and the steam inlet adjustment mechanism of the low-pressure cylinder.

[0008] Furthermore, the unit operating parameters include main steam flow, feedback value of heating extraction steam regulating valve opening, and minimum flow margin of low-pressure cylinder; External energy market data includes transient fluctuations in heating network return water temperature, step change rates of electrical load, and real-time adjustable power of thermal storage systems; External environmental data includes ambient temperature and wind speed.

[0009] Furthermore, the specific methods for determining the supply-demand deviation of thermal power load, the external demand volatility, and the adjustable capacity of the generating units based on the collected data are as follows: The main steam flow rate and the opening value of the heating extraction steam regulating valve are input into the unit's variable operating condition thermodynamic model to obtain the actual heating capacity benchmark value. The transient heat load demand is determined based on the transient fluctuation value of the heating network return water temperature. The thermal power load supply and demand deviation value is determined based on the difference between the actual heating capacity benchmark value and the transient heat load demand value. Calculate the variance of the step change rate of electrical load within a preset time window, and determine the external demand volatility based on the ratio between the variance and the real-time adjustable power of the thermal storage system. The maximum safe power output reduction is determined based on the minimum flow margin of the low-pressure cylinder and the ambient temperature. The maximum safe power output reduction is then superimposed with the real-time adjustable power of the thermal storage system to obtain the unit's adjustable capacity value.

[0010] Furthermore, the specific method for determining the dynamic coupling degree index of heat and power based on the supply and demand deviation of heat and power load, the external demand volatility, and the adjustable capacity of the unit is as follows: The supply and demand margin occupancy factor is determined based on the ratio between the supply and demand deviation of the thermal power load and the adjustable capacity of the unit. The demand shock exceedance coefficient is determined based on the ratio between the external demand volatility and the preset safe volatility threshold. The thermal-electric dynamic coupling degree index is obtained by weighted summation of the supply and demand margin occupancy coefficient and the demand shock limit excess coefficient.

[0011] Furthermore, when the thermoelectric dynamic coupling degree index meets the preset triggering conditions, the specific method for identifying key mismatch links based on the thermoelectric load supply-demand deviation value, external demand volatility, and unit adjustable capacity value is as follows: Calculate the absolute difference between the supply and demand deviation of thermal power load and the adjustable capacity of the unit; When the absolute difference exceeds the preset capacity deficit warning threshold, the insufficient static regulation capacity of the unit is identified as a critical mismatch. When the absolute difference is less than or equal to the preset capacity deficit warning threshold and the demand shock exceedance coefficient is greater than the preset dynamic response threshold, the external demand dynamic shock exceeding the unit response rate is identified as a critical mismatch.

[0012] Furthermore, the specific method for generating the corresponding electric heating demand deviation characteristics is as follows: Determine the target time that triggers the critical mismatch, obtain the corresponding thermal load supply-demand deviation value and external demand volatility at the target time, and combine the thermal load supply-demand deviation value and external demand volatility into a thermal demand deviation feature.

[0013] Furthermore, the specific method for matching the characteristics of the electrothermal demand deviation with the preset decoupling strategies in the preset decoupling strategy library to determine the target thermoelectric decoupling strategy is as follows: Calculate the first absolute distance between the thermal load supply and demand deviation value in the thermal demand deviation characteristics and the center point of the benchmark deviation threshold interval corresponding to each preset decoupling strategy, and the second absolute distance between the external demand volatility in the thermal demand deviation characteristics and the center point of the benchmark volatility interval corresponding to each preset decoupling strategy. Based on the preset deviation weight coefficient and the preset fluctuation weight coefficient, the first absolute distance and the second absolute distance are weighted and summed to obtain the comprehensive matching distance value corresponding to each preset decoupling strategy. The preset decoupling strategy with the smallest overall matching distance value is determined as the target thermoelectric decoupling strategy.

[0014] Secondly, this application proposes a thermoelectric decoupling system for a combined heat and power (CHP) unit, comprising: The data acquisition module is used to collect unit operating parameters, external energy market data, and external environmental data of the combined heat and power unit. The data processing module is used to determine the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value based on the collected data, and to determine the thermal power dynamic coupling degree index based on the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value. The mismatch identification module is used to identify key mismatches based on the thermal and electrical load supply and demand deviation, external demand volatility, and unit adjustable capacity when the thermoelectric dynamic coupling degree index meets the preset triggering conditions, and generate corresponding electric and thermal demand deviation characteristics. The decoupling strategy determination module is used to match the characteristics of the electrothermal demand deviation with each preset decoupling strategy in the preset decoupling strategy library to determine the target thermoelectric decoupling strategy. The control command output module is used to determine the target adjustment parameters of the thermal storage system and the target adjustment parameters of the low-pressure cylinder according to the target thermoelectric decoupling strategy, generate thermoelectric decoupling control commands, and send the thermoelectric decoupling control commands to the thermal storage system and the steam inlet adjustment mechanism of the low-pressure cylinder.

[0015] Furthermore, the target thermoelectric decoupling strategy includes the adjustment values ​​of the heat storage system's charge and discharge power and the adjustment values ​​of the low-pressure cylinder's steam inlet flow rate; The control command output module determines the target regulating flow rate of the thermal storage medium based on the ratio between the adjustment value of the thermal storage system's charging and discharging power and the product of the specific heat capacity of the thermal storage medium and the set temperature difference. It also determines the target opening degree of the low-pressure cylinder regulating valve based on the proportional relationship between the adjustment value of the low-pressure cylinder's steam inlet and the current total main steam flow rate of the unit.

[0016] Furthermore, the control command output module encapsulates the target regulating flow value of the thermal storage medium and the target opening degree of the low-pressure cylinder regulating valve into a thermoelectric decoupling control command that conforms to the communication protocol of the underlying actuator. The thermoelectric decoupling control command containing the target regulating flow value of the thermal storage medium is sent to the frequency converter pump of the thermal storage system, and the thermoelectric decoupling control command containing the target opening degree of the low-pressure cylinder regulating valve is sent to the steam inlet regulating valve of the low-pressure cylinder.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention collects unit operating parameters, external energy market data, and external environmental data from combined heat and power (CHP) units to comprehensively determine the CHP load supply-demand deviation, external demand volatility, and unit adjustable capacity. Based on this, a dynamic CHP coupling index is constructed. This index quantitatively assesses the current CHP coupling state of the unit from multiple dimensions, including supply-demand deviation, external shocks, and unit regulation capabilities, avoiding reliance on a single parameter or fixed threshold and improving the accuracy of CHP coupling identification. When the dynamic CHP coupling index meets preset trigger conditions, key mismatches are identified by combining the CHP load supply-demand deviation, external demand volatility, and unit adjustable capacity. This helps distinguish between different imbalance causes, such as insufficient static regulation capacity of the unit and external demand dynamic shocks exceeding the response rate, thereby improving the targeting of decoupling control. By generating corresponding electrothermal demand deviation characteristics and matching them with preset decoupling strategies in a preset decoupling strategy library, the target CHP decoupling strategy can be adaptively determined according to different operating conditions, reducing the problem of insufficient adaptability of fixed control rules to complex operating conditions. Finally, the target thermo-electric decoupling strategy is converted into specific adjustment parameters for the thermal storage system and low-pressure cylinder, and control commands are issued to the corresponding actuators. This achieves closed-loop regulation from coupling state assessment, imbalance cause identification, strategy matching to execution control, which is beneficial to improving the adjustment flexibility, response speed and heat and power supply coordination capabilities of the cogeneration unit. Attached Figure Description

[0018] Figure 1 This is a system diagram of the present invention; Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0019] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0020] like Figure 1 As shown, this embodiment provides a cogeneration unit's thermoelectric decoupling system, including a data acquisition module, a data processing module, a mismatch identification module, a decoupling strategy determination module, and a control command output module. The data acquisition module is connected to the cogeneration unit's DCS system, the plant-level SIS communication network, and the plant's meteorological station data bus. The data processing module is connected to the data acquisition module, the mismatch identification module is connected to the data processing module, the decoupling strategy determination module is connected to the mismatch identification module, and the control command output module is connected to the decoupling strategy determination module, the thermal storage system, and the low-pressure cylinder steam inlet regulating mechanism.

[0021] The data acquisition module is used to collect unit operating parameters, external energy market data, and external environmental data of the combined heat and power (CHP) unit. Specifically, the data acquisition module includes a unit-side sensor acquisition unit, a communication interface unit, and an environmental monitoring unit.

[0022] The unit-side sensing and acquisition unit connects to the DCS system at the bottom of the cogeneration unit at a preset high-frequency sampling period to acquire the main steam flow, the feedback value of the heating extraction regulating valve opening, and the minimum flow margin of the low-pressure cylinder in real time. The main steam flow reflects the total amount of steam entering the turbine, the feedback value of the heating extraction regulating valve opening reflects the current heating extraction status of the unit, and the minimum flow margin of the low-pressure cylinder reflects the margin between the current steam intake of the low-pressure cylinder and the minimum flow required for safe operation.

[0023] The communication interface unit establishes communication connections with the thermal dispatching terminal, the power grid dispatching terminal, and the DCS side of the thermal storage system through the plant-level SIS communication network. The communication interface unit can use the OPC UA protocol or the IEC 104 protocol for data exchange to obtain real-time transient fluctuations in the return water temperature of the heating network, the step change rate of the electrical load, and the real-time adjustable power of the thermal storage system.

[0024] The step rate of change of electrical load is obtained from the automatic generation control command sequence issued by the grid dispatching terminal. The communication interface unit extracts the planned output of the generating units corresponding to two adjacent sampling times from the automatic generation control command sequence, calculates the difference in planned output between adjacent sampling times, and divides the difference in planned output by the time interval between adjacent sampling times to obtain the step rate of change of electrical load. The step rate of change of electrical load is used to characterize the degree of change in grid frequency regulation and peak shaving demand per unit time.

[0025] The transient fluctuation value of the return water temperature of the heating network is obtained through the heat exchange station operation status data packet sent by the thermal dispatch terminal. The communication interface unit parses the time-series data of the temperature measurement points of the primary network return water pipeline from the heat exchange station operation status data packet, calculates the difference between the current return water temperature value and the historical average return water temperature within the sliding time window, so as to filter out the slow temperature change trend generated during the normal circulation of the heating network, and obtains the transient fluctuation value of the return water temperature of the heating network that characterizes the short-term change of heat load.

[0026] The real-time adjustable power of the thermal storage system is determined by the system's operating status data. The communication interface unit reads the current liquid level of the thermal storage tank, the upper temperature inside the tank, the lower temperature inside the tank, and the operating status of the heat exchanger. Based on the current liquid level, it determines the current storage volume of the thermal storage medium. Based on the upper and lower temperatures inside the tank, it determines the temperature difference of the thermal storage medium. Combined with the preset specific heat capacity of the thermal storage medium, it calculates the heat power that the thermal storage system can release or absorb within a preset safe liquid level range. The calculated heat power is used as the real-time adjustable power of the thermal storage system.

[0027] The environmental monitoring unit connects to the plant's meteorological station data bus to acquire real-time ambient temperature and wind speed in the area where the unit is located. Ambient temperature is used to determine the maximum safe power output reduction of the unit, while wind speed, as data characterizing external environmental conditions, is stored along with the corresponding unit operating parameters.

[0028] The data processing module is used to determine the thermal power load supply and demand deviation, external demand fluctuation rate and unit adjustable capacity value based on the collected data, and further determine the thermal power dynamic coupling degree index.

[0029] When determining the supply-demand deviation of the cogeneration load, the data processing module inputs the main steam flow rate and the opening value of the heating extraction steam regulating valve into the pre-established unit variable operating condition thermodynamic model. The unit variable operating condition thermodynamic model is established based on the steam-water heat balance relationship of the cogeneration unit. The model pre-stores heating capacity data corresponding to different main steam flow rates, different opening values ​​of the heating extraction steam regulating valve, and different low-pressure cylinder flow states.

[0030] The data processing module performs table lookup and interpolation calculations in the unit's variable operating condition thermodynamic model based on the current main steam flow and the feedback value of the heating extraction steam regulating valve opening. This determines the maximum extraction steam heating capacity that the cogeneration unit can provide when meeting the minimum flow margin requirement of the low-pressure cylinder, and uses the maximum extraction steam heating capacity as the benchmark value for the actual heating capacity.

[0031] The data processing module also inputs the transient fluctuation values ​​of the return water temperature of the heating network into the preset heating network thermal dynamic model. The heating network thermal dynamic model is used to describe the correspondence between changes in the return water temperature of the heating network and changes in transient heat load on the user side. The data processing module converts the transient fluctuation values ​​of the return water temperature of the heating network into transient heat load demand based on the heating network thermal dynamic model.

[0032] Subtracting the actual heating capacity benchmark from the transient heat load demand yields the heat and power load supply-demand deviation, i.e.: The deviation between heat and power load supply and demand = the actual heating capacity benchmark value - the transient heat load demand.

[0033] The thermal power load supply-demand deviation value is used to indicate the degree of deviation between the current heating capacity of the generating unit and the transient heat load demand of the heating network. When the absolute value of the thermal power load supply-demand deviation value increases, it indicates that the mismatch between the heating capacity of the generating unit and the heat load demand of the heating network increases.

[0034] When determining the volatility of external demand, the data processing module establishes a preset time window and continuously acquires the step change rate of electrical load within this preset time window. In this embodiment, the preset time window can be set to 5 minutes. The data processing module calculates the variance of the electrical load step change rate sequence within 5 minutes to characterize the dispersion and severity of grid load changes.

[0035] The data processing module compares the variance with the real-time adjustable power of the thermal storage system, and determines the external demand volatility based on the ratio between the variance and the real-time adjustable power of the thermal storage system. External demand volatility = variance of the electric load step change rate sequence ÷ real-time adjustable power of the thermal storage system.

[0036] External demand volatility is used to characterize the buffering pressure of a current thermal storage system against external electrical and thermal demand shocks. When electrical load changes drastically and the real-time adjustable power of the thermal storage system is small, external demand volatility increases; when the thermal storage system has a large capacity for adjusting heat charge and discharge, external demand volatility decreases accordingly.

[0037] When determining the adjustable capacity of the unit, the data processing module determines the maximum safe power output reduction allowed for the cogeneration unit under the conditions of not triggering low-pressure cylinder blow-out, blade overheating, or other safety restrictions, based on the minimum flow margin of the low-pressure cylinder and the current ambient temperature.

[0038] The data processing module superimposes the maximum safe power output reduction with the real-time adjustable power of the thermal storage system to obtain the unit's adjustable capacity value. Specifically, the absolute value of the maximum safe power output reduction can be added to the absolute value of the real-time adjustable power of the thermal storage system to represent the total adjustment range that the cogeneration unit can provide by reducing power generation output and by the thermal storage system absorbing or releasing heat.

[0039] After obtaining the thermal power load supply-demand deviation, external demand volatility, and unit adjustable capacity, the data processing module determines the supply-demand margin occupancy factor based on the ratio between the thermal power load supply-demand deviation and the unit adjustable capacity. The supply-demand margin occupancy factor indicates the degree to which the current thermal power load supply-demand deviation occupies the unit's remaining regulating capacity.

[0040] The data processing module determines the demand shock exceedance coefficient based on the ratio between the external demand volatility and the preset safe fluctuation threshold. The demand shock exceedance coefficient is used to represent the degree to which the current external electric and heat demand shock exceeds the unit's safe tolerance capacity.

[0041] The preset safety fluctuation threshold is determined based on the historical operating data of the cogeneration unit. Specifically, the time series data of external demand volatility for the 30 days prior to the current moment, during which no thermoelectric coupling alarm occurred and the cogeneration unit maintained stable operation, is retrieved. The 95% confidence interval of the external demand volatility time series data is calculated, and the upper limit of the 95% confidence interval is set as the preset safety fluctuation threshold.

[0042] The preset safety fluctuation threshold represents the maximum range of external demand fluctuations that the existing coordinated control system of the cogeneration unit can absorb without significant oscillations in internal operating parameters under the current equipment health condition, relying on the unit's own inertia. When the actual external demand fluctuation rate exceeds the preset safety fluctuation threshold, it indicates that conventional coordinated control methods are insufficient to eliminate external demand shocks.

[0043] The data processing module performs a weighted summation of the supply-demand margin occupancy coefficient and the demand shock exceedance coefficient to obtain the thermo-electric dynamic coupling degree index. In this embodiment, the weight of the supply-demand margin occupancy coefficient is set to 0.6, and the weight of the demand shock exceedance coefficient is set to 0.4, that is: Thermoelectric dynamic coupling degree index = 0.6 × supply and demand margin utilization coefficient + 0.4 × demand shock limit coefficient.

[0044] The weight of the supply-demand margin occupancy factor is greater than that of the demand shock exceedance factor because the unit's adjustable capacity is the foundation for maintaining the balance between heat and power supply and demand, and its occupancy level has a more direct limiting effect on the thermoelectric coupling state. In other implementations, the above weights can also be calibrated according to the regulation performance of different unit models.

[0045] The mismatch identification module is used to determine whether the thermoelectric dynamic coupling degree index meets the preset trigger condition. In this embodiment, the preset trigger condition is that the thermoelectric dynamic coupling degree index is greater than the preset coupling warning threshold, which is set to 0.75.

[0046] The preset coupling warning threshold is determined based on the safety margin of the unit's DCS system for primary frequency regulation and heating supply guarantee. When the thermoelectric dynamic coupling degree index is greater than 0.75, it indicates that the unit's remaining regulation space has been compressed to a critical state that easily triggers automatic power generation control assessment or heating capacity failure. The mismatch identification module then initiates the location analysis of key mismatch links.

[0047] During the location analysis, the mismatch identification module first calculates the absolute difference between the thermal and power load supply and demand deviation value and the unit's adjustable capacity value, and then compares the absolute difference with the preset capacity deficit warning threshold.

[0048] The preset capacity deficit warning threshold can be set to 15% of the rated heating capacity of the cogeneration unit. This threshold indicates the capacity deficit limit at which the unit's current adjustable capacity cannot make up for the gap between heat and power supply and demand, and measures such as cutting off some unnecessary industrial steam extraction or starting desuperheating and pressure reducing devices are required.

[0049] When the absolute difference between the thermal power load supply and demand deviation and the unit's adjustable capacity exceeds the preset capacity deficit warning threshold, it indicates that the unit's existing adjustment space cannot make up for the current thermal power supply and demand gap. The mismatch identification module identifies the unit's insufficient static adjustment capacity as a key mismatch.

[0050] When the absolute difference between the thermal load supply and demand deviation value and the unit's adjustable capacity value is less than or equal to the preset capacity deficit warning threshold, it indicates that the unit can meet the current adjustment demand in terms of capacity. The mismatch identification module further compares the demand impact limit coefficient with the preset dynamic response threshold.

[0051] In this embodiment, the preset dynamic response threshold is set to 1.2. This threshold represents the rate of fluctuation in external electric and heat demand reaching 1.2 times the maximum closed-loop response bandwidth of the cogeneration unit's coordinated control system. When the demand surge limit factor is greater than 1.2, it indicates that the rate of change in external demand exceeds the response capability of the unit's control algorithm and actuators. The mismatch identification module identifies the external demand dynamic surge exceeding the unit's response rate as a critical mismatch.

[0052] After identifying the key mismatch, the mismatch identification module determines the target time that triggers the key mismatch and obtains the corresponding thermal and power load supply-demand deviation value and external demand volatility at the target time.

[0053] To avoid the impact of measurement errors at a single moment on the identification results, the mismatch identification module can extract the operating data from 5 seconds before the target time to 10 seconds after the target time, and determine the thermal and power load supply and demand deviation value and external demand fluctuation rate corresponding to the target time based on the extracted operating data.

[0054] The supply-demand deviation of thermal power load and the volatility of external demand are combined to form the thermal power demand deviation characteristic. For example, when the critical mismatch is that the dynamic shock of external demand exceeds the unit's response rate, if the supply-demand deviation of thermal power load at the target time is +45MW and the volatility of external demand is 12.5% / min, then the generated thermal power demand deviation characteristic can be expressed as: [45, 12.5].

[0055] The electric heat demand deviation characteristic is used to characterize the combined state of the heat and power supply and demand gap and the rate of change of external demand under the current operating conditions.

[0056] The decoupling strategy determination module has a pre-set decoupling strategy library. The decoupling strategy library includes multiple preset decoupling strategies, each of which is associated with a benchmark deviation threshold range, a benchmark volatility range, the thermal storage system's charge and release heat power adjustment value, and the low-pressure cylinder steam inlet adjustment value.

[0057] The benchmark deviation threshold range and benchmark volatility range in the decoupling strategy library are calibrated based on the historical decoupling action records of the cogeneration unit, the maximum heat charging and discharging capacity of the thermal storage system, the safe steam inlet boundary of the low-pressure cylinder, and the response bandwidth of the unit's coordinated control system.

[0058] In this embodiment, the reference deviation threshold range can be divided into: The slight deviation range is [0, 20MW], with the center point of the range being 10MW; The medium deviation range (20MW, 50MW) has a center point of 35MW. The severely deviated range is (50MW, 100MW), with the center point of the range being 75MW.

[0059] The benchmark volatility range can be divided into: The range of fluctuation is [0, 5% / min], with the center point of the range being 2.5% / min; Rapid fluctuation range (5% / min, 15% / min], with the center point of the range being 10% / min; The extreme impact range is greater than 15% / min, and the corresponding midpoint of the range is set to 20% / min.

[0060] The decoupling strategy determination module calculates the first absolute distance between the thermal load supply and demand deviation value in the thermal demand deviation characteristics and the center point of the benchmark deviation threshold interval corresponding to each preset decoupling strategy, and the second absolute distance between the external demand volatility in the thermal demand deviation characteristics and the center point of the benchmark volatility interval corresponding to each preset decoupling strategy.

[0061] Based on the preset deviation weight coefficient and the preset fluctuation weight coefficient, the first absolute distance and the second absolute distance are weighted and summed to obtain the comprehensive matching distance value corresponding to each preset decoupling strategy, i.e.: The overall matching distance value = preset deviation weight coefficient × first absolute distance + preset fluctuation weight coefficient × second absolute distance.

[0062] In this embodiment, the preset deviation weighting coefficient is set to 0.7, and the preset fluctuation weighting coefficient is set to 0.3.

[0063] For example, if the current electric heating demand deviation characteristics are [45MW, 12% / min], for a preset decoupling strategy where the benchmark deviation threshold range is a medium deviation range and the benchmark volatility range is a rapid volatility range, the center point of the benchmark deviation threshold range is 35MW and the center point of the benchmark volatility range is 10% / min.

[0064] The first absolute distance is: |45-35|=10.

[0065] The second absolute distance is: |12-10|=2.

[0066] The comprehensive matching distance value corresponding to the preset decoupling strategy is: 0.7×10+0.3×2=7.6.

[0067] The decoupling strategy determination module calculates the comprehensive matching distance value between the electrothermal demand deviation characteristics and the other preset decoupling strategies in the decoupling strategy library in the same way. It then iterates through all the comprehensive matching distance values ​​and determines the preset decoupling strategy with the smallest comprehensive matching distance value as the target thermoelectric decoupling strategy.

[0068] The target thermoelectric decoupling strategy includes adjusting the heat release / discharge power of the thermal storage system and the steam inlet flow rate of the low-pressure cylinder. For operating conditions where the unit's static regulation capacity is insufficient, the target thermoelectric decoupling strategy can prioritize increasing the heat release or absorption power of the thermal storage system to expand the equivalent regulation capacity of the cogeneration unit. For operating conditions where dynamic external demand shocks exceed the unit's response rate, the target thermoelectric decoupling strategy can coordinate and adjust the heat release / discharge power of the thermal storage system and the steam inlet flow rate of the low-pressure cylinder to utilize the thermal storage system to quickly respond to changes in external demand and gradually restore the unit's thermoelectric balance through low-pressure cylinder steam inlet regulation.

[0069] The control command output module determines the target regulation parameters of the thermal storage system based on the adjustment value of the thermal power charging and discharging of the thermal storage system in the target thermoelectric decoupling strategy. The target regulation parameter of the thermal storage system is the target regulation flow rate value of the thermal storage medium.

[0070] The control command output module acquires the specific heat capacity of the thermal storage medium and the set temperature difference of the thermal storage system. Based on the ratio between the adjusted value of the thermal storage system's charging and discharging heat power and the product of the specific heat capacity of the thermal storage medium and the set temperature difference, it determines the target regulating flow rate value of the thermal storage medium, i.e.: Target flow rate of thermal storage medium = Adjustment value of thermal storage system charge and discharge power ÷ (Specific heat capacity of thermal storage medium × Set temperature difference).

[0071] For example, when the target thermoelectric decoupling strategy requires the thermal storage system to release 10MW of thermal power, the control command output module obtains the specific heat capacity of the thermal storage medium and the set temperature difference of the thermal storage system. The thermal storage medium can be demineralized water with a specific heat capacity set to 4.18 kJ / (kg·℃), and the set temperature difference on the heat release side of the thermal storage system is set to 40℃. The control command output module converts 10MW to 10000 kJ / s and calculates the target regulating flow rate of the thermal storage medium based on the above relationship.

[0072] The control command output module also determines the target adjustment parameters for the low-pressure cylinder based on the low-pressure cylinder steam inlet adjustment value in the target thermoelectric decoupling strategy. The target adjustment parameter for the low-pressure cylinder is the target opening degree of the low-pressure cylinder regulating valve.

[0073] The control command output module acquires the current total main steam flow rate of the unit in real time and determines the target opening degree of the low-pressure cylinder regulating valve based on the proportional relationship between the low-pressure cylinder steam inlet adjustment value and the current total main steam flow rate of the unit. For example, when the target thermoelectric decoupling strategy requires a reduction of 50 t / h in the low-pressure cylinder steam inlet, and the current total main steam flow rate of the unit is 1000 t / h, the target opening degree of the low-pressure cylinder regulating valve is determined according to the following formula: Low-pressure cylinder regulating valve target opening = 1 - low-pressure cylinder steam inlet adjustment value ÷ current unit main steam total flow rate.

[0074] Therefore, the target opening degree of the low-pressure cylinder regulating valve is calculated as follows: 1 - 50 ÷ 1000 = 95%.

[0075] The control command output module encapsulates the target regulating flow rate of the thermal storage medium and the target opening degree of the low-pressure cylinder regulating valve into thermoelectric decoupled control commands that conform to the communication protocol of the underlying actuator. The communication protocol of the underlying actuator can be Modbus TCP or PROFIBUS.

[0076] The control command output module writes the target regulating flow value of the thermal storage medium into the communication register address corresponding to the frequency converter pump of the thermal storage system, and sends the thermoelectric decoupling control command containing the target regulating flow value of the thermal storage medium to the frequency converter pump of the thermal storage system, so that the frequency converter pump of the thermal storage system operates according to the target flow.

[0077] The control command output module writes the target opening degree of the low-pressure cylinder regulating valve into the communication register address corresponding to the low-pressure cylinder inlet steam regulating valve, and sends the thermoelectric decoupling control command containing the target opening degree of the low-pressure cylinder regulating valve to the low-pressure cylinder inlet steam regulating valve, so that the low-pressure cylinder inlet steam regulating valve is adjusted to the corresponding target opening degree.

[0078] By converting the macroscopic thermal storage system's charge and discharge power adjustment values ​​and the low-pressure cylinder's steam inlet adjustment values ​​into the target flow rate that the thermal storage system's variable frequency pump can execute and the target opening degree that the low-pressure cylinder's steam inlet regulating valve can execute, the conversion error and response delay between the control and execution layers of the decoupling strategy can be reduced.

[0079] like Figure 2 As shown in the figure, this embodiment also provides a thermoelectric decoupling method for a combined heat and power unit, which specifically includes the following steps.

[0080] First, the main steam flow rate of the cogeneration unit, the feedback value of the opening of the heating extraction steam regulating valve, and the minimum flow margin of the low-pressure cylinder are collected. The transient fluctuation value of the return water temperature of the heating network, the step change rate of the electrical load, and the real-time adjustable power of the thermal storage system are also collected. Ambient temperature and wind speed are also collected.

[0081] Secondly, the supply and demand deviation of thermal power load is determined based on the main steam flow rate, the feedback value of the opening of the heating extraction steam regulating valve, and the transient fluctuation value of the return water temperature of the heating network; the external demand fluctuation rate is determined based on the variance of the step change rate of electrical load within the preset time window and the real-time adjustable power of the thermal storage system; and the unit's adjustable capacity value is determined based on the minimum flow margin of the low-pressure cylinder, the ambient temperature, and the real-time adjustable power of the thermal storage system.

[0082] Then, the supply and demand margin occupancy coefficient is determined based on the supply and demand deviation of the thermal power load and the adjustable capacity of the unit. The demand shock limit exceedance coefficient is determined based on the external demand volatility and the preset safety fluctuation threshold. The supply and demand margin occupancy coefficient and the demand shock limit exceedance coefficient are weighted and summed to obtain the thermal power dynamic coupling degree index.

[0083] When the thermoelectric dynamic coupling degree index is greater than the preset coupling warning threshold, the absolute difference between the thermoelectric load supply and demand deviation and the unit's adjustable capacity is calculated. When the absolute difference is greater than the preset capacity deficit warning threshold, the insufficient static regulation capacity of the unit is identified as a critical mismatch. When the absolute difference is less than or equal to the preset capacity deficit warning threshold, and the demand surge exceedance coefficient is greater than the preset dynamic response threshold, the external demand dynamic surge exceeding the unit's response rate is identified as a critical mismatch.

[0084] After identifying the key mismatch, the thermal load supply-demand deviation value and external demand volatility corresponding to the target time that triggers the key mismatch are obtained, and the two are combined to form the thermal demand deviation characteristics.

[0085] Subsequently, the absolute distances between the characteristics of the electrothermal demand deviation and the center points of the benchmark deviation threshold intervals and the benchmark volatility intervals corresponding to each preset decoupling strategy in the decoupling strategy library are calculated respectively. The absolute distances are weighted and summed to obtain the comprehensive matching distance value. The preset decoupling strategy with the smallest comprehensive matching distance value is determined as the target thermo-electric decoupling strategy.

[0086] Finally, the target regulating flow rate of the thermal storage medium is determined based on the adjustment value of the thermal storage system's charging and discharging heat power in the target thermo-electric decoupling strategy, and the target opening degree of the low-pressure cylinder regulating valve is determined based on the adjustment value of the low-pressure cylinder's steam inlet flow rate. The target regulating flow rate of the thermal storage medium and the target opening degree of the low-pressure cylinder regulating valve are encapsulated into thermo-electric decoupling control commands, which are then sent to the thermal storage system's variable frequency pump and the low-pressure cylinder's steam inlet regulating valve, respectively, to complete the thermo-electric decoupling regulation of the cogeneration unit.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for thermoelectric decoupling of a combined heat and power (CHP) unit, characterized in that, Includes the following steps: Collect unit operating parameters, external energy market data, and external environmental data for combined heat and power units; Based on the collected data, determine the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value; and determine the thermal power dynamic coupling degree index based on the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value. When the thermoelectric dynamic coupling degree index meets the preset triggering conditions, key mismatch links are identified based on the thermoelectric load supply and demand deviation value, external demand volatility and unit adjustable capacity value, and corresponding electric and heat demand deviation characteristics are generated. The characteristics of the electrothermal demand deviation are matched with the preset decoupling strategies in the preset decoupling strategy library to determine the target thermo-electric decoupling strategy; Based on the target thermoelectric decoupling strategy, the target adjustment parameters of the thermal storage system and the low-pressure cylinder are determined, and thermoelectric decoupling control commands are generated and sent to the thermal storage system and the steam inlet adjustment mechanism of the low-pressure cylinder.

2. The thermoelectric decoupling method for a combined heat and power unit according to claim 1, characterized in that, The unit's operating parameters include main steam flow, feedback value of the heating extraction steam regulating valve opening, and minimum flow margin of the low-pressure cylinder; External energy market data includes transient fluctuations in heating network return water temperature, step change rates of electrical load, and real-time adjustable power of thermal storage systems; External environmental data includes ambient temperature and wind speed.

3. The thermoelectric decoupling method for a combined heat and power unit according to claim 2, characterized in that, The specific methods for determining the supply-demand deviation of thermal power load, the volatility of external demand, and the adjustable capacity of generating units based on the collected data are as follows: Input the feedback values ​​of the main steam flow rate and the opening of the heating extraction steam regulating valve into the unit's variable operating condition thermodynamic model to obtain the actual heating capacity benchmark value. Determine the transient heat load demand based on the transient fluctuation value of the heating network return water temperature. Determine the thermal power load supply and demand deviation value based on the difference between the actual heating capacity benchmark value and the transient heat load demand value. Calculate the variance of the step change rate of electrical load within a preset time window, and determine the external demand volatility based on the ratio between the variance and the real-time adjustable power of the thermal storage system. The maximum safe power output reduction is determined based on the minimum flow margin of the low-pressure cylinder and the ambient temperature. The maximum safe power output reduction is then superimposed with the real-time adjustable power of the thermal storage system to obtain the unit's adjustable capacity value.

4. The thermoelectric decoupling method for a combined heat and power unit according to claim 1, characterized in that, The specific method for determining the dynamic coupling degree index of heat and power based on the supply and demand deviation of heat and power load, the volatility of external demand, and the adjustable capacity of the unit is as follows: The supply and demand margin occupancy factor is determined based on the ratio between the supply and demand deviation of the thermal power load and the adjustable capacity of the unit. The demand shock exceedance coefficient is determined based on the ratio between the external demand volatility and the preset safe volatility threshold. The thermal-electric dynamic coupling degree index is obtained by weighted summation of the supply and demand margin occupancy coefficient and the demand shock limit excess coefficient.

5. The thermoelectric decoupling method for a combined heat and power unit according to claim 1, characterized in that, When the thermo-electric dynamic coupling degree index meets the preset triggering conditions, the specific method for identifying key mismatch links based on the thermo-electric load supply-demand deviation value, external demand volatility, and unit adjustable capacity value is as follows: Calculate the absolute difference between the supply and demand deviation of thermal power load and the adjustable capacity of the unit; When the absolute difference exceeds the preset capacity deficit warning threshold, the insufficient static regulation capacity of the unit is identified as a critical mismatch. When the absolute difference is less than or equal to the preset capacity deficit warning threshold and the demand shock exceedance coefficient is greater than the preset dynamic response threshold, the external demand dynamic shock exceeding the unit response rate is identified as a critical mismatch.

6. The thermoelectric decoupling method for a combined heat and power unit according to claim 5, characterized in that, The specific method for generating the corresponding electric heating demand deviation characteristics is as follows: Determine the target time that triggers the critical mismatch, obtain the corresponding thermal load supply-demand deviation value and external demand volatility at the target time, and combine the thermal load supply-demand deviation value and external demand volatility into a thermal demand deviation feature.

7. The thermoelectric decoupling method for a combined heat and power unit according to claim 1, characterized in that, The specific method for matching the characteristics of the electrothermal demand deviation with the preset decoupling strategies in the preset decoupling strategy library to determine the target thermoelectric decoupling strategy is as follows: Calculate the first absolute distance between the thermal load supply and demand deviation value in the thermal demand deviation characteristics and the center point of the benchmark deviation threshold interval corresponding to each preset decoupling strategy, and the second absolute distance between the external demand volatility in the thermal demand deviation characteristics and the center point of the benchmark volatility interval corresponding to each preset decoupling strategy. Based on the preset deviation weight coefficient and the preset fluctuation weight coefficient, the first absolute distance and the second absolute distance are weighted and summed to obtain the comprehensive matching distance value corresponding to each preset decoupling strategy. The preset decoupling strategy with the smallest overall matching distance value is determined as the target thermoelectric decoupling strategy.

8. A thermoelectric decoupling system for a combined heat and power (CHP) unit, characterized in that, include: The data acquisition module is used to collect unit operating parameters, external energy market data, and external environmental data of the combined heat and power unit. The data processing module is used to determine the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value based on the collected data, and to determine the thermal power dynamic coupling degree index based on the thermal power load supply-demand deviation value, external demand volatility, and unit adjustable capacity value. The mismatch identification module is used to identify key mismatches based on the thermal and electrical load supply and demand deviation, external demand volatility, and unit adjustable capacity when the thermoelectric dynamic coupling degree index meets the preset triggering conditions, and generate corresponding electric and thermal demand deviation characteristics. The decoupling strategy determination module is used to match the characteristics of the electrothermal demand deviation with each preset decoupling strategy in the preset decoupling strategy library to determine the target thermoelectric decoupling strategy. The control command output module is used to determine the target adjustment parameters of the thermal storage system and the target adjustment parameters of the low-pressure cylinder according to the target thermoelectric decoupling strategy, generate thermoelectric decoupling control commands, and send the thermoelectric decoupling control commands to the thermal storage system and the steam inlet adjustment mechanism of the low-pressure cylinder.

9. A thermoelectric decoupling system for a combined heat and power unit according to claim 8, characterized in that, The target thermoelectric decoupling strategy includes adjusting the heat storage system's charge and release power and adjusting the low-pressure cylinder's steam inlet flow rate. The control command output module determines the target regulating flow rate of the thermal storage medium based on the ratio between the adjustment value of the thermal storage system's charging and discharging power and the product of the specific heat capacity of the thermal storage medium and the set temperature difference. It also determines the target opening degree of the low-pressure cylinder regulating valve based on the proportional relationship between the adjustment value of the low-pressure cylinder's steam inlet and the current total main steam flow rate of the unit.

10. A thermoelectric decoupling system for a combined heat and power unit according to claim 9, characterized in that, The control command output module encapsulates the target regulating flow value of the thermal storage medium and the target opening degree of the low-pressure cylinder regulating valve into a thermoelectric decoupling control command that conforms to the communication protocol of the underlying actuator. The thermoelectric decoupling control command containing the target regulating flow value of the thermal storage medium is sent to the frequency converter pump of the thermal storage system, and the thermoelectric decoupling control command containing the target opening degree of the low-pressure cylinder regulating valve is sent to the steam inlet regulating valve of the low-pressure cylinder.

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