Heat collection-heat storage system flow regulation and control method for improving flexibility of light-coal-storage complementary power generation system

Abstract

The invention discloses a heat collection-heat storage system flow regulation and control method for improving the flexibility of a light-coal-storage complementary power generation system. The light-coal-storage complementary power generation system comprises a coal-fired power generation unit and a heat collection-heat storage system. With the control targets of coping with solar fluctuation and meeting the rapid load change requirement of the light-coal-storage complementary power generation system, the actual value of the mass flow of a working medium on the heat collector side is calculated and adjusted by collecting the solar radiation intensity and the operation data of the light-coal-storage complementary power generation system; the change rate of the water supply mass flow entering the working medium-water heat exchanger is calculated on line according to the variable quantity required by the working capacity of unit steam, and the actual value of the water supply mass flow entering the working medium-water heat exchanger and the actual value of the working medium mass flow of the working medium-water heat exchanger side are adjusted; and after the variable load instruction is finished, a model prediction control algorithm is adopted to update the actual values of the feed water mass flow entering the working medium-water heat exchanger and the working medium mass flow on the working medium-water heat exchanger side. The method can improve the operation flexibility of the system and is simple to operate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of operation control of multi-energy complementary power generation system, and particularly relates to a heat collection and storage system flow regulation method for improving flexibility of light coal storage complementary power generation system. BACKGROUND

[0002] Renewable energy utilization is developing rapidly, and the position of coal-fired power generation in power production is gradually changing from the main energy to the foundation and flexible regulation energy. Due to the intermittency, periodicity and instability of renewable energy, the flexibility demand of power system is greatly increased, and the variable load range and frequency of coal-fired generating units will gradually increase. Directly complementing solar energy and conventional fossil energy in the thermal system to build a system is one of the effective solutions to the challenges faced by the transformation of diversified energy structure. However, due to the strong time-varying nature of solar energy and the variable load demand of coal-fired power generation units, the input and output of light coal complementary power generation system are prone to frequent changes, and improving the variable load capacity of the system under light disturbance conditions is the key to the flexible and efficient operation of light coal complementary power generation system.

[0003] The existing light coal complementary power generation system has the problem of limited flexibility, and most control strategies only consider how to respond to solar disturbance, without considering optimizing the control of the storage system to improve the variable load capacity of the complementary system. At present, there is no reasonable heat collection and storage system flow regulation method to improve the variable load performance of the complementary system under different weather conditions, and to realize the flexible and efficient operation of the light coal storage complementary power generation system. SUMMARY

[0004] In order to improve the flexibility of light coal storage complementary system, the purpose of the present application is to provide a heat collection and storage system flow regulation method for improving the flexibility of light coal storage complementary power generation system, wherein the light coal storage complementary power generation system comprises a coal-fired power generation unit and a heat collection and storage system. The method collects solar radiation intensity and operation data of the light coal storage complementary power generation system, calculates and adjusts the actual value of the working medium mass flow rate on the heat collector side, calculates the change rate of the feedwater mass flow rate into the working medium-water heat exchanger and adjusts the feedwater mass flow rate into the working medium-water heat exchanger and the actual value of the working medium mass flow rate on the working medium-water heat exchanger side according to the required change amount of unit steam work capacity, and updates the actual value of the feedwater mass flow rate into the working medium-water heat exchanger and the working medium mass flow rate on the working medium-water heat exchanger side after the variable load instruction is completed using the model predictive control algorithm. The variable load capacity of the system can be improved, and the influence of solar radiation intensity disturbance on the operation parameters of the light coal storage complementary power generation system can also be responded to, so as to ensure the safe, flexible and stable operation of the system.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: A method for flow control of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system, comprising a coal-fired generator unit and a solar collector-storage system; firstly, collecting solar radiation intensity and operational data of the coal-fired generator unit and the solar collector-storage system; the operational data of the coal-fired generator unit includes real-time load and feedwater inlet enthalpy, feedwater outlet enthalpy, feedwater inlet flow rate, and feedwater outlet flow rate of the regenerator unit; the operational data of the solar collector-storage system includes feedwater mass flow rate into the working fluid-water heat exchanger, working fluid mass flow rate on the working fluid-water heat exchanger side, working fluid mass flow rate on the collector side, feedwater outlet temperature of the working fluid-water heat exchanger, working fluid inlet temperature of the working fluid-water heat exchanger, working fluid outlet temperature of the working fluid-water heat exchanger, working fluid inlet temperature of the collector, and working fluid outlet temperature of the collector. The process involves several steps: First, based on the solar radiation intensity and the deviation between the setpoint and real-time value of the collector working fluid outlet temperature, the actual value of the working fluid mass flow rate on the collector side is calculated. Next, based on the change in the unit steam work capacity, the rate of change of the feedwater mass flow rate entering the working fluid-water heat exchanger during the load change process is calculated online, and the actual value of the feedwater mass flow rate entering the working fluid-water heat exchanger is adjusted. Then, the actual value of the working fluid mass flow rate on the working fluid-water heat exchanger side is calculated, and the working fluid mass flow rate on the working fluid-water heat exchanger side is adjusted to the calculated value to meet the rapid load change requirements of the solar-coal-storage complementary power generation system. After the load change command ends, a model predictive control algorithm is used to update the actual values ​​of the feedwater mass flow rate entering the working fluid-water heat exchanger and the actual value of the working fluid mass flow rate on the working fluid-water heat exchanger side. The specific calculation steps are as follows: Step 1: Calculate the setpoint and actual value of the working fluid mass flow rate on the collector side. The specific sub-steps are as follows: 1) Calculate the set value of the working fluid mass flow rate on the collector side at the current moment. D wm1,sp In the formula, D wm1,sp The setpoint for the working fluid mass flow rate on the collector side is kg / s; DNI is the solar radiation intensity, kW / m². 2 ; θ The angle of incidence of the sun, in °; A The light-collecting area of ​​the condenser lens is m. 2 ; η s The efficiency of the solar collector in absorbing solar energy includes the collector's optical efficiency, shading loss, terminal loss, and incident angle correction factor, in percentages (%). Q loss The heat loss of the solar collector is expressed in kW. c wm Specific heat capacity of the working fluid in the heat collection-storage system, kJ / (kg·℃); T h,inTc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; T c,out Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; 2) The actual value of the collector side working medium mass flow rate at the current time is calculated, which is the sum of the set value of the collector side working medium mass flow rate and the correction value of the collector side working medium mass flow rate, and is calculated by the following formula: In the formula, D wm1 Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; D wm1 Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; Step 2: Calculate the actual value of the feed water mass flow rate entering the working medium-water heat exchanger at the current time in the variable load process, and the specific sub-steps are as follows: 1) Calculate the required change amount Δ H req In the formula, Δ H req Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; W SCref Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; R p Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; m fw Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; 2) Calculate the set value of the feed water mass flow rate change rate into the working medium-water heat exchanger at the current time in the variable load process k w1,sp In the formula, k w1,sp Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; 2 τ k Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; k Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; k Tc is the collector working medium outlet temperature, i.e. the hot tank working medium inlet temperature, ℃; y , k = x , x ​+1,… z ; y This refers to the number of high-pressure regenerative heaters; x The number of stages of the highest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system; z The number of stages of the lowest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system; η k For the first k The extraction efficiency of the high-pressure regenerative heater; h solar,out The current enthalpy of the working fluid-water heat exchanger feedwater outlet is given in kJ / kg. h wx,out The enthalpy of the feedwater outlet of the highest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system at the current moment is expressed in kJ / kg. η x-1 The extraction efficiency of a high-pressure regenerative heater that is one stage higher than the highest-stage high-pressure regenerative heater connected in parallel with the heat collection-storage system; Δ t The time interval is s; 3) Calculate the actual rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger at the current moment during the variable load process. This rate is the sum of the setpoint for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger and the correction value for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger, calculated using the following formula: In the formula, k w1 The current value of the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger, in kg / s. 2 ; c rh The correction value for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger is related to the maximum allowable reheat steam temperature deviation, kg / s 2 ; 4) Calculate the actual mass flow rate of feedwater entering the working fluid-water heat exchanger at the current moment during the variable load process. D w In the formula, D w ( t () represents the actual mass flow rate of the feedwater entering the working fluid-water heat exchanger at the current moment, in kg / s; D w ( t Δ t () represents the actual mass flow rate of the feedwater entering the working fluid-water heat exchanger at the previous moment, in kg / s; Step 3: Calculate the actual value of the working medium mass flow rate of the working medium-water heat exchanger side at the current time D wm2 In the formula, D wm2 is the actual value of the working medium mass flow rate of the working medium-water heat exchanger side at the current time, kg / s; D w is the actual value of the feedwater mass flow rate entering the working medium-water heat exchanger at the current time, kg / s; h solar,out,set is the set value of the working medium-water heat exchanger feedwater outlet enthalpy, related to the load rate deviation and the reheating steam temperature deviation, kJ / kg; h w,in is the working medium-water heat exchanger feedwater inlet enthalpy, kJ / kg; T h,out is the working medium-water heat exchanger working medium inlet temperature, i.e., the hot tank working medium outlet temperature, ℃; T c,in is the working medium-water heat exchanger working medium outlet temperature, i.e., the cold tank working medium inlet temperature, ℃; Step 4: Determine whether the variable load instruction of the solar coal storage complementary power generation system is finished, and when the variable load instruction is finished, update the feedwater mass flow rate entering the working medium-water heat exchanger calculation using the model predictive control algorithm before the next variable load instruction is executed, and the specific sub-steps are as follows: 1) Establish a prediction model: obtain three prediction models of the collector side working medium mass flow rate changing with the solar radiation intensity DNI, the working medium-water heat exchanger side working medium mass flow rate changing with the working medium-water heat exchanger feedwater mass flow rate, and the storage tank liquid level changing with the storage tank inlet and outlet mass flow rate difference through data identification on the collector side working medium mass flow rate, the solar radiation intensity DNI, the working medium-water heat exchanger side working medium mass flow rate, the working medium-water heat exchanger feedwater mass flow rate, the storage tank liquid level, and the storage tank inlet and outlet mass flow rate difference; 2) Data prediction: based on the prediction data of the solar radiation intensity DNI change at the future N time points, the prediction value of the collector side working medium mass flow rate is calculated through the prediction model of the collector side working medium mass flow rate changing with the solar radiation intensity DNI, and then the prediction values of the working medium-water heat exchanger side working medium mass flow rate and the storage tank liquid level under different working medium-water heat exchanger feedwater mass flow rates at the future N time points are calculated through the prediction models of the working medium-water heat exchanger side working medium mass flow rate changing with the working medium-water heat exchanger feedwater mass flow rate and the storage tank liquid level changing with the storage tank inlet and outlet mass flow rate difference; 3) solving optimization: setting the control target as the minimum change of the liquid level of the storage tank, and the constraint condition as the mass flow rate of the feed water into the working medium-water heat exchanger being within the interval range of 95% of the total mass flow rate of the feed water, 5% 95% of the interval range and meeting the regulation requirement of the variable load instruction at the future N time points, and then solving the optimal control sequence value of the mass flow rate of the feed water into the working medium-water heat exchanger at the future N time points; 4) execution: executing the first value of the optimal control sequence of the mass flow rate of the feed water into the working medium-water heat exchanger, and updating the calculation of the mass flow rate of the feed water into the working medium-water heat exchanger at the current time point as: In the formula, k w2 The change rate of the mass flow rate of the feed water into the working medium-water heat exchanger is related to the operation stability of the solar coal storage complementary power generation system, kg / s 2 ; At the next time point, the actual data of the collector-side working medium mass flow rate, the working medium-water heat exchanger-side working medium mass flow rate and the liquid level of the storage tank are collected, compared with the predicted values of the collector-side working medium mass flow rate, the working medium-water heat exchanger-side working medium mass flow rate and the liquid level of the storage tank respectively, and the prediction model error is corrected; 5) before the variable load instruction is executed, the steps of data prediction, solving optimization and execution are repeated.

[0006] The present application has the following advantages: (1) The actual value of the collector-side working medium mass flow rate is regulated in the present application to cope with the disturbance of the solar radiation intensity. Since the change rate of the mass flow rate of the feed water into the working medium-water heat exchanger is calculated, the photoelectric and coal conversion characteristics of the solar coal storage complementary power generation system in the transient process are considered, and the actual values of the mass flow rate of the feed water into the working medium-water heat exchanger and the working medium-water heat exchanger-side working medium mass flow rate are regulated to make up for the insufficient variable load capacity of the steam turbine, so as to improve the variable load capacity of the system while coping with the solar fluctuation, and ensure the safe, flexible and stable operation of the system.

[0007] (2) The change rate of the mass flow rate of the feed water into the working medium-water heat exchanger is calculated by the change amount required by the unit steam work capacity in the present application, which is simple to operate and easy to implement.

[0008] (3) The liquid level limit of the storage tank is considered in the present application, and the model prediction control algorithm is used to calculate the mass flow rate of the feed water into the working medium-water heat exchanger after the variable load instruction is ended, so as to ensure the safe operation of the storage tank and long-term support. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1A flow regulation method for a heat collection and storage system for improving the flexibility of a light-coal storage complementary power generation system.

[0010] Figure 2 A coupling mode schematic diagram of the heat collection and storage system. DETAILED DESCRIPTION

[0011] The application will be further described in detail below with reference to the drawings and specific embodiments.

[0012] As shown in the drawings, Figure 1 A flow regulation method for a heat collection and storage system for improving the flexibility of a light-coal storage complementary power generation system, the light-coal storage complementary power generation system comprising a coal-fired generator set and a heat collection and storage system; first, collecting solar radiation intensity, coal-fired generator set and heat collection and storage system operation data; the coal-fired generator set operation data includes real-time load and regenerative heater group feedwater inlet enthalpy, feedwater outlet enthalpy, feedwater inlet flow rate, feedwater outlet flow rate; the heat collection and storage system operation data includes feedwater mass flow rate into the working medium-water heat exchanger, working medium mass flow rate on the working medium-water heat exchanger side, working medium mass flow rate on the collector side, working medium-water heat exchanger feedwater outlet temperature, working medium inlet temperature of the working medium-water heat exchanger, working medium outlet temperature of the working medium-water heat exchanger, collector working medium inlet temperature, collector working medium outlet temperature; then, according to the deviation of solar radiation intensity, collector working medium outlet temperature set value and real-time value, the actual value of working medium mass flow rate on the collector side is calculated; then, according to the required change amount of unit steam work capacity, the working medium mass flow rate change rate into the working medium-water heat exchanger in the variable load process is calculated online and the actual value of working medium mass flow rate into the working medium-water heat exchanger is adjusted, and then the actual value of working medium mass flow rate on the working medium-water heat exchanger side is calculated, and then the working medium mass flow rate on the working medium-water heat exchanger side is adjusted to the calculated value to meet the rapid variable load demand of the light-coal storage complementary power generation system; after the variable load instruction is completed, the model predictive control algorithm is used to update the actual values of working medium mass flow rate into the working medium-water heat exchanger and working medium mass flow rate on the working medium-water heat exchanger side; the specific calculation steps are as follows: Step 1: Calculate the set value and actual value of working medium mass flow rate on the collector side, and the specific sub-steps are as follows: 1) Calculate the set value of working medium mass flow rate on the collector side at the current time D wm1,sp In the formula, D wm1,sp The set value of working medium mass flow rate on the collector side is kg / s; DNI is the solar radiation intensity, kW / m 2 ; θ The solar incident angle is °; A The light collection area of the concentrator is m2 ; η s is the efficiency of the collector absorbing solar energy, including collector optical efficiency, shading loss, end loss and incident angle correction factor, %; Q loss is the heat loss of the collector, kW; c wm is the specific heat capacity of the working medium of the collector-thermal storage system, kJ / (kg·℃); T h,in is the outlet temperature of the working medium of the collector, i.e. the inlet temperature of the working medium of the hot tank, ℃; T c,out is the inlet temperature of the working medium of the collector, i.e. the outlet temperature of the working medium of the cold tank, ℃; 2) calculating the actual value of the mass flow rate of the working medium on the collector side at the current time, which is the sum of the set value of the mass flow rate of the working medium on the collector side and the correction value of the mass flow rate of the working medium on the collector side, calculated by the following formula: In the formula, D wm1 is the actual value of the mass flow rate of the working medium on the collector side, kg / s; Δ D wm1 is the correction value of the mass flow rate of the working medium on the collector side, related to the deviation of the set value and the actual value of the outlet temperature of the working medium of the collector, kg / s; Step 2: calculating the actual value of the mass flow rate of the feed water entering the working medium-water heat exchanger at the current time during the variable load process, the specific sub-steps are: 1) calculating the required change amount Δ H req In the formula, Δ H req is the required change amount of the unit steam work capacity at the current time, kJ / kg; W SCref is the reference power of the photo-coal storage complementary power generation system, kW; Δ R p is the deviation of the actual value and the set value of the load rate, %; m fw is the total mass flow rate of the feed water at the current time, kg / s; 2) calculating the set value of the change rate of the mass flow rate of the feed water entering the working medium-water heat exchanger at the current time during the variable load process k w1,sp In the formula, k w1,spThe set value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger at the current time, kg / s 2 ; τ k The unit feed water enthalpy rise of the high-pressure regenerative heater of the first k stage, kJ / kg, the number of the high-pressure regenerative heater k is recorded as 1 to y , k = x , x +1,… z ; y The number of the high-pressure regenerative heaters; x The stage number of the highest-stage high-pressure regenerative heater connected in parallel with the heat collection and storage system; z The stage number of the lowest-stage high-pressure regenerative heater connected in parallel with the heat collection and storage system; η k The extraction efficiency of the high-pressure regenerative heater of the first k stage; h solar,out The enthalpy of the feed water outlet of the working medium-water heat exchanger at the current time, kJ / kg; h wx,out The enthalpy of the feed water outlet of the highest-stage high-pressure regenerative heater connected in parallel with the heat collection and storage system at the current time, kJ / kg; η x-1 The extraction efficiency of the high-pressure regenerative heater of a stage higher than the highest-stage high-pressure regenerative heater connected in parallel with the heat collection and storage system; Δ t The time interval, s; 3) The actual value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger at the current time in the variable load process is calculated, which is the sum of the set value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger and the correction value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger, and is calculated by the following formula: In the formula, k w1 The actual value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger at the current time, kg / s 2 ; c rh The correction value of the mass flow rate variation of the feed water entering the working medium-water heat exchanger, which is related to the maximum allowed deviation of the reheat steam temperature, kg / s 2 ; 4) The actual value of the mass flow rate of the feed water entering the working medium-water heat exchanger at the current time in the variable load process is calculated D w wherein, D w t is the actual value of the mass flow rate of feedwater entering the working medium-water heat exchanger at the current time, kg / s; D w t Δ t is the actual value of the mass flow rate of feedwater entering the working medium-water heat exchanger at the previous time, kg / s; Step 3: Calculate the actual value of the mass flow rate of working medium on the working medium-water heat exchanger side at the current time D wm2 wherein, D wm2 is the actual value of the mass flow rate of working medium on the working medium-water heat exchanger side at the current time, kg / s; D w is the actual value of the mass flow rate of feedwater entering the working medium-water heat exchanger at the current time, kg / s; h solar,out,set is the set value of the enthalpy of feedwater outlet of the working medium-water heat exchanger, related to the load rate deviation and the reheating steam temperature deviation, kJ / kg; h w,in is the enthalpy of feedwater inlet of the working medium-water heat exchanger, kJ / kg; T h,out is the working medium inlet temperature of the working medium-water heat exchanger, i.e. the working medium outlet temperature of the hot tank, ℃; T c,in is the working medium outlet temperature of the working medium-water heat exchanger, i.e. the working medium inlet temperature of the cold tank, ℃; Step 4: Determine whether the variable load instruction of the solar coal storage complementary power generation system is finished, when the variable load instruction is finished, the mass flow rate of feedwater entering the working medium-water heat exchanger is updated by using the model predictive control algorithm before the next variable load instruction is executed, and the specific sub-steps are as follows: 1) Establish a prediction model: three prediction models of the working medium mass flow rate on the collector side varying with the solar radiation intensity DNI, the working medium mass flow rate on the working medium-water heat exchanger side varying with the mass flow rate of feedwater entering the working medium-water heat exchanger, and the storage tank liquid level varying with the mass flow rate difference between the storage tank inlet and outlet are obtained through data identification of the working medium mass flow rate on the collector side, the solar radiation intensity DNI, the working medium mass flow rate on the working medium-water heat exchanger side, the mass flow rate of feedwater entering the working medium-water heat exchanger, the storage tank liquid level, and the mass flow rate difference between the storage tank inlet and outlet; ​​2) Data prediction: based on the prediction data of the variation of solar radiation intensity DNI in the next N time points, the predicted value of the collector-side working medium mass flow rate is calculated through the prediction model of the collector-side working medium mass flow rate varying with the solar radiation intensity DNI, and then the predicted values of the working medium-water heat exchanger-side working medium mass flow rate and the storage tank liquid level under different feedwater mass flow rates entering the working medium-water heat exchanger in the next N time points are calculated through the prediction model of the working medium-water heat exchanger-side working medium mass flow rate varying with the feedwater mass flow rate entering the working medium-water heat exchanger and the storage tank liquid level varying with the mass flow rate difference between the storage tank inlet and outlet; 3) Optimization solving: the control objective is set as the minimum variation of the storage tank liquid level, the constraint conditions are that the storage tank liquid level is controlled within the set liquid level limit, the feedwater mass flow rate entering the working medium-water heat exchanger is within the total feedwater mass flow rate 5% that changes within the interval range of 95% and meets the variable load instruction adjustment requirement in the next N time points, and then the optimal control sequence value of the feedwater mass flow rate entering the working medium-water heat exchanger in the next N time points is solved; 4) Execution: the first value of the optimal control sequence of the feedwater mass flow rate entering the working medium-water heat exchanger is executed, and the calculation of the feedwater mass flow rate entering the working medium-water heat exchanger in the current time point is updated as: wherein, k w2 is the feedwater mass flow rate variation rate, which is related to the operation stability of the coal-fired storage complementary power generation system, kg / s 2 ; The actual data of the collector-side working medium mass flow rate, the working medium-water heat exchanger-side working medium mass flow rate and the storage tank liquid level in the next time point are collected, compared with the predicted values of the collector-side working medium mass flow rate, the working medium-water heat exchanger-side working medium mass flow rate and the storage tank liquid level respectively, and the prediction model error is corrected; 5) Before the variable load instruction is executed, the steps of data prediction, optimization solving and execution are repeated.

[0013] As a preferred embodiment of the present application, as shown in Figure 2 the collector-storage system comprises a collector, a hot tank, a working medium-water heat exchanger and a cold tank connected in sequence, the working medium-water heat exchanger feedwater inlet is connected in communication with the high-pressure regenerative heater feedwater inlet of the coal-fired power generating unit through a feedwater regulating valve, and the working medium-water heat exchanger feedwater outlet is connected in communication with the high-pressure regenerative heater feedwater outlet through a pipeline.

[0014] As the preferred embodiment of the present application, the collector of the light-coal storage complementary power generation system stops operating when the solar radiation intensity is 0, and the collector-storage system stops operating when the liquid level of the hot tank or the cold tank reaches the limit, so as to ensure that the collector-storage system can meet the long-term stable operation requirement safely.

[0015] As the preferred embodiment of the present application, in the sub-step 4) of step 2, the mass flow rate of the feed water entering the working medium-water heat exchanger has a variation limit, the lower limit being the minimum value obtained under the condition that a certain margin is maintained before the load reduction, and the upper limit being the maximum value obtained under the condition that a certain margin is maintained before the load increase, so as to ensure the safe operation of the working medium-water heat exchanger and the high-pressure regenerative heater.

[0016] As the preferred embodiment of the present application, the collector-storage system of the light-coal storage complementary power generation system is connected in parallel with the primary or multi-stage high-pressure regenerative heater, which can effectively replace part of the high-pressure regenerative heater steam extraction, and is conducive to the sufficient provision of the change amount required by the unit steam work capacity of the collector-storage system.

[0017] The method for regulating the mass flow rates of the working medium and the feed water of the collector-storage system to meet the rapid load variation requirement of the light-coal storage complementary power generation system, the operation data of the light-coal storage complementary power generation system and the solar radiation intensity are collected, the actual value of the working medium mass flow rate of the collector side is calculated and adjusted, the change rate of the feed water mass flow rate entering the working medium-water heat exchanger is calculated online according to the change amount required by the unit steam work capacity, and the feed water mass flow rate entering the working medium-water heat exchanger and the actual value of the working medium mass flow rate of the working medium-water heat exchanger side are adjusted, the actual values of the feed water mass flow rate entering the working medium-water heat exchanger and the working medium mass flow rate of the working medium-water heat exchanger side are updated after the load variation instruction is completed by using the model predictive control algorithm, which is conducive to improving the load variation capacity of the system, and can also cope with the influence of the solar radiation intensity disturbance on the operation parameters of the light-coal storage complementary power generation system, so as to ensure the safe, flexible and stable operation of the system.

Claims

1. A method for flow regulation of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system, characterized in that: The solar-coal-storage complementary power generation system includes a coal-fired generator set and a solar collector-storage system. First, it collects data on solar radiation intensity and the operation of the coal-fired generator set and the solar collector-storage system. The coal-fired generator set operation data includes real-time load and feedwater inlet enthalpy, feedwater outlet enthalpy, feedwater inlet flow rate, and feedwater outlet flow rate of the regenerator unit. The solar collector-storage system operation data includes feedwater mass flow rate into the working fluid-water heat exchanger, working fluid mass flow rate on the working fluid-water heat exchanger side, working fluid mass flow rate on the collector side, feedwater outlet temperature of the working fluid-water heat exchanger, working fluid inlet temperature of the working fluid-water heat exchanger, working fluid outlet temperature of the working fluid-water heat exchanger, working fluid inlet temperature of the collector, and working fluid outlet temperature of the collector. Then, based on solar radiation intensity and solar collector... The deviation between the setpoint and real-time value of the working fluid outlet temperature is used to calculate the actual value of the working fluid mass flow rate on the collector side. Next, based on the change in the unit steam work capacity, the rate of change of the feedwater mass flow rate entering the working fluid-water heat exchanger during the load change process is calculated online, and the actual value of the feedwater mass flow rate entering the working fluid-water heat exchanger is adjusted. Then, the actual value of the working fluid mass flow rate on the working fluid-water heat exchanger side is calculated, and the working fluid mass flow rate on the working fluid-water heat exchanger side is adjusted to the calculated value to meet the rapid load change requirements of the solar-coal-storage complementary power generation system. After the load change command ends, a model predictive control algorithm is used to update the actual values ​​of the feedwater mass flow rate entering the working fluid-water heat exchanger and the actual value of the working fluid mass flow rate on the working fluid-water heat exchanger side. The specific calculation steps are as follows: Step 1: Calculate the setpoint and actual value of the working fluid mass flow rate on the collector side. The specific sub-steps are as follows: 1) Calculate the set value of the working fluid mass flow rate on the collector side at the current moment. D wm1,sp In the formula, D wm1,sp This is the setpoint for the mass flow rate of the working fluid on the collector side, in kg / s; DNI is solar radiation intensity, kW / m² 2 ; θ The angle of incidence of the sun, in °; A The light-collecting area of ​​the condenser lens is m. 2 ; η s The efficiency of the solar collector in absorbing solar energy includes the collector's optical efficiency, shading loss, terminal loss, and incident angle correction factor, in percentages (%). Q loss For the heat loss of the solar collector, kW; c wm Specific heat capacity of the working fluid in the heat collection-storage system, kJ / (kg·℃); T h,in The working fluid outlet temperature of the solar collector is the same as the working fluid inlet temperature of the heat tank, in °C. T c,out The temperature at which the working fluid enters the collector is the same as the temperature at which the working fluid exits the cold tank, in °C. 2) Calculate the actual value of the working fluid mass flow rate on the collector side at the current moment. This value is the sum of the setpoint and the correction value of the working fluid mass flow rate on the collector side, calculated using the following formula: In the formula, D wm1 The actual mass flow rate of the working fluid on the collector side, kg / s; Δ D wm1 This is a correction value for the mass flow rate of the working fluid on the collector side, which is related to the deviation between the set value and the actual value of the working fluid outlet temperature of the collector, in kg / s; Step 2: Calculate the actual mass flow rate of feedwater entering the working fluid-water heat exchanger at the current moment during the variable load process. The specific sub-steps are as follows: 1) Calculate the change in the work capacity required per unit steam to perform during the variable load process at the current moment, Δ H req In the formula, Δ H req The change in work capacity required to perform work per unit of steam at the current moment, expressed in kJ / kg; W SCref The reference power for the photovoltaic-coal-storage complementary power generation system is kW; Δ R p The deviation between the actual load factor and the set value, % m fw The total water supply mass flow rate at the current moment is expressed in kg / s. 2) Calculate the setpoint for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger at the current moment during the variable load process. k w1,sp In the formula, k w1,sp The setpoint for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger at the current moment, in kg / s 2 ; τ k For the first k The unit feedwater enthalpy rise of the high-pressure regenerative heater, kJ / kg, and the heater's serial number. k The pressures from highest to lowest are numbered 1 to 1. y , k = x , x +1,… z ; y This refers to the number of high-pressure regenerative heaters; x The number of stages of the highest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system; z The number of stages of the lowest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system; η k For the first k The extraction efficiency of the high-pressure regenerative heater; h solar,out The current enthalpy of the working fluid-water heat exchanger feedwater outlet is given in kJ / kg. h wx,out The enthalpy of the feedwater outlet of the highest-level high-pressure regenerative heater connected in parallel with the heat collection-storage system at the current moment is expressed in kJ / kg. η x-1 The extraction efficiency of a high-pressure regenerative heater that is one stage higher than the highest-stage high-pressure regenerative heater connected in parallel with the heat collection-storage system; Δ t The time interval is s; 3) Calculate the actual rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger at the current moment during the variable load process. This rate is the sum of the setpoint for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger and the correction value for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger, calculated using the following formula: In the formula, k w1 The current value of the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger, in kg / s. 2 ; c rh The correction value for the rate of change of feedwater mass flow rate entering the working fluid-water heat exchanger is related to the maximum allowable reheat steam temperature deviation, kg / s 2 ; 4) Calculate the actual mass flow rate of feedwater entering the working fluid-water heat exchanger at the current moment during the variable load process. D w In the formula, D w ( t () represents the actual mass flow rate of the feedwater entering the working fluid-water heat exchanger at the current moment, in kg / s; D w ( t Δ t () represents the actual mass flow rate of the feedwater entering the working fluid-water heat exchanger at the previous moment, in kg / s; Step 3: Calculate the actual mass flow rate of the working fluid on the working fluid-water heat exchanger side at the current moment. D wm2 In the formula, D wm2 The actual mass flow rate of the working fluid on the working fluid-water heat exchanger side at the current moment, in kg / s; D w The actual mass flow rate of the feedwater entering the working fluid-water heat exchanger at the current moment, in kg / s; h solar,out,set The setpoint for the enthalpy at the feedwater outlet of the working fluid-water heat exchanger is related to the load rate deviation and the reheat steam temperature deviation, in kJ / kg. h w,in The enthalpy of the feedwater inlet of the working fluid-water heat exchanger is given in kJ / kg. T h,out The working fluid inlet temperature of the working fluid-water heat exchanger is the same as the working fluid outlet temperature of the hot tank, in °C. T c,in The working fluid outlet temperature of the working fluid-water heat exchanger, i.e., the working fluid inlet temperature of the cold tank, is in °C. Step 4: Determine whether the load change command of the solar-coal-storage complementary power generation system has ended. When the load change command has ended, before the next load change command is executed, the model predictive control algorithm is used to update the feedwater mass flow rate calculation entering the working fluid-water heat exchanger. The specific sub-steps are as follows: 1) Establish prediction models: By identifying the data of working fluid mass flow rate on the collector side, solar radiation intensity DNI, working fluid mass flow rate on the working fluid-water heat exchanger side, feedwater mass flow rate entering the working fluid-water heat exchanger, tank level, and the difference in mass flow rate between the tank inlet and outlet, three prediction models were obtained: working fluid mass flow rate on the collector side changes with solar radiation intensity DNI, working fluid mass flow rate on the working fluid-water heat exchanger side changes with feedwater mass flow rate entering the working fluid-water heat exchanger, and tank level changes with the difference in mass flow rate between the tank inlet and outlet. 2) Data prediction: Based on the predicted data of the change of solar radiation intensity DNI at N future time points, the predicted value of the working fluid mass flow rate on the collector side is calculated by using the prediction model of the change of solar radiation intensity DNI on the collector side. Then, using the prediction model of the change of working fluid mass flow rate on the working fluid-water heat exchanger side with the change of feedwater mass flow rate entering the working fluid-water heat exchanger and the change of tank liquid level with the change of the difference between the mass flow rates at the tank inlet and outlet, the predicted values ​​of the working fluid mass flow rate and tank liquid level on the working fluid-water heat exchanger side under different feedwater mass flow rates entering the working fluid-water heat exchanger at N future time points are calculated. 3) Optimization Solution: The control objective is to minimize the change in tank liquid level, with constraints that the tank liquid level is controlled within the set limit and the feedwater mass flow rate entering the working fluid-water heat exchanger is 5% of the total feedwater mass flow rate. The feedwater mass flow rate varies within 95% of the interval and meets the variable load command regulation requirements for the next N time periods. Then, the optimal control sequence value of the feedwater mass flow rate entering the working fluid-water heat exchanger within the next N time periods is obtained by solving. 4) Execution: Execute the first value of the optimal control sequence for the feedwater mass flow rate entering the working fluid-water heat exchanger. The calculated and updated feedwater mass flow rate entering the working fluid-water heat exchanger at the current moment is as follows: In the formula, k w2 The rate of change in the feedwater mass flow rate entering the working fluid-water heat exchanger is related to the operational stability of the photovoltaic-coal-storage complementary power generation system, kg / s 2 ; At the next moment, collect the actual data of the working fluid mass flow rate on the collector side, the working fluid mass flow rate on the working fluid-water heat exchanger side, and the liquid level in the storage tank. Compare these data with the predicted values ​​of the working fluid mass flow rate on the collector side, the working fluid mass flow rate on the working fluid-water heat exchanger side, and the liquid level in the storage tank, and correct the prediction model error. 5) Before executing the variable load command, repeat the steps of data prediction, solution optimization and execution.

2. The method for flow regulation of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system according to claim 1, characterized in that: The heat collection-storage system includes a heat collector, a hot tank, a working fluid-water heat exchanger, and a cold tank connected in sequence. The feed water inlet of the working fluid-water heat exchanger is connected to the feed water inlet of the high-pressure regenerative heater of the coal-fired generator set through a feed water regulating valve, and the feed water outlet of the working fluid-water heat exchanger is connected to the feed water outlet of the high-pressure regenerative heater through a pipeline.

3. The method for flow regulation of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system according to claim 1, characterized in that: The solar collectors of the solar-coal-storage complementary power generation system stop operating when the solar radiation intensity is 0, and the solar collector-storage system stops operating after the liquid level in the hot or cold tank reaches the limit.

4. The method for flow regulation of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system according to claim 1, characterized in that: In step 2, sub-step 4), the mass flow rate of the feedwater entering the working fluid-water heat exchanger during the load change process has a limit to its variation. The lower limit is the minimum value obtained under the condition of maintaining a certain margin before the load reduction, and the upper limit is the maximum value obtained under the condition of maintaining a certain margin before the load increase.

5. The method for flow regulation of a solar collector-storage system to improve the flexibility of a solar-coal-storage complementary power generation system according to claim 1, characterized in that: The solar-coal-storage complementary power generation system operates in parallel with one or more high-pressure regenerative heaters.

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