A coordinated control method for a trough-type solar thermal power plant
By establishing the relationship between load and flow rate through function fitting and PID regulation, the coordinated control problem of parabolic trough solar thermal power plants was solved, and the coordinated regulation of the heat transfer oil and molten salt pumps was realized, thus optimizing the system's operational stability and grid adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU NUCLEAR POWER RES INST CO LTD
- Filing Date
- 2023-10-08
- Publication Date
- 2026-06-02
Smart Images
Figure CN117419468B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar thermal power plant control technology, and in particular to a coordinated control method for parabolic trough solar thermal power plants. Background Technology
[0002] A solar thermal power generation system consists of a heat collection subsystem, a heat transfer system, a heat storage and heat exchange subsystem, and a power generation system. Solar thermal power generation systems are classified into four types based on the heat collection method: tower, trough, Fresnel, and dish. The solar thermal power generation industry started earlier abroad, with over 50 years of research conducted on materials, design, processes, and theories, and commercial applications already achieved.
[0003] Currently, parabolic trough solar thermal power generation technology is one of the mainstream commercial solar thermal power generation technologies. Although related technologies have received widespread attention, there is still no specific method for its coordinated control. The main control problems of parabolic trough solar thermal power plants are as follows: the conventional island, solar island, and heat storage and exchange system are controlled separately, relying entirely on control personnel to manually coordinate the start-up, operation, and shutdown of these islands; and the flow rate of the main heat transfer oil pump is also manually controlled. In summary, there is currently no coordinated control method for parabolic trough solar thermal power plants.
[0004] The above background information is provided only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teaching. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention
[0005] To overcome the shortcomings of existing technologies, this invention provides a coordinated control method for parabolic trough solar thermal power plants, the specific technical solution of which is as follows:
[0006] A coordinated control method for a parabolic trough solar thermal power plant is provided. The parabolic trough solar thermal power plant includes a steam generator, a steam turbine generator, an oil-salt heat exchanger, a thermal oil pump, and a thermal storage system. The thermal storage system includes a hot salt tank, a cold salt tank, and a hot molten salt pump. The steam generator is connected to the steam turbine generator through a steam pipe. The thermal oil pump, the steam generator, and the oil-salt heat exchanger are sequentially connected through thermal oil pipes to form a loop. The hot salt tank, the hot molten salt pump, the oil-salt heat exchanger, and the cold salt tank are sequentially connected through molten salt pipes.
[0007] The coordinated control method is used for the operation adjustment of a parabolic trough solar thermal power plant under the sliding pressure operation of the turbine generator and the heat release mode of the thermal storage system. It includes the following steps: based on historical operating data of the load and heat transfer oil flow rate of the parabolic trough solar thermal power plant, a first empirical function relating the load and heat transfer oil flow rate is obtained through function fitting; considering the influence of different temperature differences at the inlet and outlet of the steam generator on the result of obtaining the first empirical function, temperature compensation correction is applied to the first empirical function to obtain a first correction function, thereby obtaining the corrected heat transfer oil flow rate; based on historical operating data of the load deviation and molten salt pump frequency of the parabolic trough solar thermal power plant, a second empirical function relating the load deviation and molten salt pump frequency is obtained through function fitting, where the load deviation is the difference between the target load and the actual load.
[0008] Based on the first correction function and the second empirical function, and combined with the current target load, the corrected heat transfer oil flow rate and the hot molten salt pump frequency are obtained, and the heat transfer oil pump and the hot molten salt pump are adjusted to achieve matching.
[0009] Furthermore, the formula for the first correction function is as follows:
[0010] F1(x)=(90.74-Δ)×y+y
[0011] In the formula, Δ is the temperature difference between the hot end of the heat transfer oil at the evaporator inlet and the hot end of the heat transfer oil at the evaporator outlet, x is the target load, and y is the heat transfer oil flow rate.
[0012] Furthermore, when the steam turbine generator is in sliding pressure operation, the regulating valve of the steam turbine generator is fully open or the opening degree remains unchanged to keep the main steam temperature basically unchanged, and the output load is adjusted by the heat transfer oil to regulate the main steam flow and pressure.
[0013] Furthermore, the target load of the parabolic trough solar thermal power plant fluctuates according to the grid AGC control requirements, thereby adjusting the heat transfer oil pump and the hot molten salt pump accordingly.
[0014] Furthermore, in the heat release mode, the thermal storage system of the parabolic trough solar thermal power plant heats water into steam through the hot salt tank of the thermal storage system to promote the operation of the steam turbine generator.
[0015] Furthermore, the parabolic trough solar thermal power plant also includes a concentrating collector, a hot oil manifold, a cold oil manifold, a heating furnace, a first regulating valve, and a second regulating valve. The concentrating collector, the hot oil manifold, the first regulating valve, the heating furnace, the second regulating valve, the heat transfer oil pump, and the cold oil manifold are connected in sequence to form a circuit. The first regulating valve is used to automatically regulate the pressure of the heat transfer oil header, and the second regulating valve is used to automatically regulate the inlet temperature of the heat transfer oil entering the heat transfer oil pump.
[0016] Furthermore, the parabolic trough solar thermal power plant also includes an outlet regulating valve, which is located between the hot molten salt pump and the oil-salt heat exchanger, and is used to automatically regulate the outlet pressure of the hot molten salt pump.
[0017] Furthermore, after receiving the load command, the parabolic trough solar thermal power plant obtains the target load by performing frequency regulation, speed limiting, and amplitude limiting, and then calculates the heat transfer oil flow rate through the first correction function.
[0018] Furthermore, the heat transfer oil flow rate, heat transfer oil pump main pipe pressure, heat transfer oil pump inlet temperature, and hot molten salt pump outlet pressure are all regulated by single-impulse PID control.
[0019] Furthermore, the outlet temperature of the heat transfer oil in the oil-salt heat exchanger is controlled by a single-impulse PID controller.
[0020] Compared with the prior art, the present invention has the following advantages: by utilizing the correspondence between the load of the parabolic trough solar thermal power plant, the flow rate of the heat transfer oil and the flow rate of the hot molten salt pump, the coordinated control of the generator units is realized in the sliding pressure operation heat release mode, thereby meeting the grid AGC control requirements. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the process framework of the coordinated control method for a parabolic trough solar thermal power plant provided in an embodiment of the present invention;
[0022] Figure 2 This is a schematic diagram of the main coordination control logic (SAMA) in the coordination control method for a parabolic trough solar thermal power plant provided in an embodiment of the present invention.
[0023] Figure 3 This is a schematic diagram of automatic SAMA for heat transfer oil flow in the coordinated control method for parabolic trough solar thermal power plants provided in an embodiment of the present invention.
[0024] Figure 4 This is a schematic diagram of the automatic SAMA (Self-Controlled Amplifier) for heat transfer oil temperature in the coordinated control method for parabolic trough solar thermal power plants provided in this embodiment of the invention.
[0025] The attached diagram is labeled as follows: 1-First regulating valve, 2-Second regulating valve, 3-Outlet regulating valve, 4-Steam generator, 5-Oil-salt converter. Detailed Implementation
[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0028] In one embodiment of the present invention, a coordinated control method for a parabolic trough solar thermal power plant is provided, see [link to relevant documentation]. Figure 1 The parabolic trough solar thermal power plant includes a steam generator 4, a steam turbine generator, an oil-salt heat exchanger 5, a thermal oil pump, and a thermal storage system. The thermal storage system includes a hot salt tank, a cold salt tank, and a hot molten salt pump. The steam generator is connected to the steam turbine generator through a steam pipe. The thermal oil pump, the steam generator, and the oil-salt heat exchanger are connected in sequence through thermal oil pipes to form a loop. The hot salt tank, the hot molten salt pump, the oil-salt heat exchanger, and the cold salt tank are connected in sequence through molten salt pipes.
[0029] The coordinated control method is used for the operation adjustment of the parabolic trough solar thermal power plant in the sliding pressure operation of the turbine generator and the heat release mode of the thermal storage system. The coordinated control method uses a computer to control the parabolic trough solar thermal power plant in the form of a coordinated control system.
[0030] The coordinated control method includes the following steps: based on historical operating data of the load and heat transfer oil flow rate of the parabolic trough solar thermal power plant, a first empirical function relating the load and heat transfer oil flow rate is obtained through function fitting; considering the influence of different temperature differences at the steam generator inlet and outlet on the result of obtaining the first empirical function, temperature compensation correction is applied to the first empirical function to obtain a first correction function, thereby obtaining the corrected heat transfer oil flow rate; based on historical operating data of the load deviation and molten salt pump frequency of the parabolic trough solar thermal power plant, a second empirical function relating the load deviation and molten salt pump frequency is obtained through function fitting, wherein the load deviation is the difference between the target load and the actual load; based on the first correction function and the second empirical function, combined with the current target load, the corrected heat transfer oil flow rate and molten salt pump frequency are obtained, and the heat transfer oil pump and molten salt pump are adjusted to achieve matching.
[0031] In this system, the turbine generator operates under sliding pressure, with its regulating valve fully open or at a constant opening to maintain a relatively constant main steam temperature. The output load is regulated by adjusting the main steam flow and pressure using heat transfer oil. The target load of the parabolic trough solar thermal power plant fluctuates according to the grid's AGC control requirements, thereby adjusting the heat transfer oil pump and molten salt pump accordingly. In the heat release mode, the thermal storage system of the parabolic trough solar thermal power plant heats water into steam using the molten salt in the thermal storage system to promote the operation of the turbine generator. Sliding pressure operation, also known as variable pressure operation, refers to a mode where the regulating valve is fully open or at a constant opening to maintain a relatively constant main steam temperature, and the load is regulated by adjusting the main steam flow and pressure using heat transfer oil when the turbine generator operates under different conditions. Heat release mode refers to a mode where the solar thermal power plant uses the heat stored in the thermal storage system to heat water into steam to generate electricity.
[0032] The parabolic trough solar thermal power plant also includes a concentrating collector, a hot oil manifold, a cold oil manifold, a heater, a first regulating valve, and a second regulating valve. The concentrating collector, hot oil manifold, first regulating valve 1, heater, second regulating valve 2, heat transfer oil pump, and cold oil manifold are sequentially connected to form a loop. The first regulating valve is used to automatically regulate the pressure of the heat transfer oil header, and the second regulating valve is used to automatically regulate the inlet temperature of the heat transfer oil entering the heat transfer oil pump. The parabolic trough solar thermal power plant also includes an outlet regulating valve 3, which is located between the molten salt pump and the oil-salt heat exchanger and is used to automatically regulate the outlet pressure of the molten salt pump.
[0033] This embodiment utilizes the correspondence between load, heat transfer oil flow rate, and hot molten salt pump flow rate to automatically adjust the generator set load by controlling the frequency of the heat transfer oil pump and the frequency of the hot molten salt rock.
[0034] Specifically, the coordinated control method requires the cooperation of multiple automatic logics. Among them, the main coordinated control logic, the automatic logic for heat transfer oil flow, and the automatic logic for heat transfer oil temperature at the hot end of the oil-salt heat exchanger outlet are essential logics in this embodiment. Once an automatic loop is disconnected, the coordinated control will be disconnected. The conditions for coordinating control to be engaged or disengaged are not listed in this embodiment and should be configured according to the actual situation of the unit.
[0035] See the main logic of coordination and control. Figure 2 The load command undergoes frequency adjustment, speed limiting, and amplitude limiting, and then the heat transfer oil flow command is calculated using the first correction function, as shown in the following formula:
[0036] F1(x)=(90.74-Δ)×y+y
[0037] In the formula, Δ is the temperature difference between the hot end of the heat transfer oil at the evaporator inlet and the hot end of the heat transfer oil at the evaporator outlet, x is the target load, y is the empirical heat transfer oil flow rate, and F1 is the corrected heat transfer oil flow rate. This includes, but is not limited to, the following historical empirical values: x = 5.65, y = 535.77; x = 10.44, y = 832.26; x = 15.45, y = 1061.72; x = 20.68, y = 1276.66; x = 25.42, y = 1585.72; x = 30.35, y = 1754.93; x = 35.33, y = 2044.71; x = 40.82, y = 2266.07.
[0038] See the automatic logic for heat transfer oil flow. Figure 3 Single-impulse PID control; automatic logic for inlet temperature of the heat transfer oil pump, single-impulse PID control; automatic logic for outlet pressure of the molten salt pump, single-impulse PID control; automatic logic for main pipe pressure of the field heat transfer oil pump, single-impulse PID control.
[0039] See the automatic logic for the hot end temperature control of the oil-salt heat exchanger outlet. Figure 4 The controlled variable is the difference between the hot salt temperature and the heat transfer oil temperature, achieved through single-impulse PID regulation of three pumps. The second empirical function is as follows:
[0040] F2(a)=b
[0041] In the formula, a represents the load deviation, and b represents the frequency of the molten salt pump. This includes, but is not limited to, the following historical experience pairs: a = -50, b = -1.5; a = -3, b = -1.5; a = -2, b = -1; a = -1, b = -0.5; a = 0, b = 0; a = 1, b = 0.5; a = 2, b = 1; a = 3, b = 1.5; a = 50, b = 1.5.
[0042] The coordinated control method for parabolic trough solar thermal power plants provided by this invention utilizes the correspondence between the load of the parabolic trough solar thermal power plant, the flow rate of the heat transfer oil, and the flow rate of the hot molten salt pump to achieve coordinated control of the generating units under the sliding pressure operation heat release mode, thereby meeting the grid AGC control requirements.
[0043] The above description is merely a preferred embodiment of the present invention and does not limit its patent scope. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A coordinated control method for a parabolic trough solar thermal power plant, characterized in that, The parabolic trough solar thermal power plant includes a steam generator, a steam turbine generator, an oil-salt heat exchanger, a thermal oil pump, and a thermal storage system. The thermal storage system includes a hot salt tank, a cold salt tank, and a hot molten salt pump. The steam generator is connected to the steam turbine generator through a steam pipe. The thermal oil pump, steam generator, and oil-salt heat exchanger are connected in sequence through thermal oil pipes to form a loop. The hot salt tank, hot molten salt pump, oil-salt heat exchanger, and cold salt tank are connected in sequence through molten salt pipes. The coordinated control method is used for the operation adjustment of a parabolic trough solar thermal power plant under the sliding pressure operation of the turbine generator and the heat release mode of the thermal storage system. It includes the following steps: based on historical operating data of the load and heat transfer oil flow rate of the parabolic trough solar thermal power plant, a first empirical function relating the load and heat transfer oil flow rate is obtained through function fitting; considering the influence of different temperature differences at the inlet and outlet of the steam generator on the result of obtaining the first empirical function, temperature compensation correction is applied to the first empirical function to obtain a first correction function, thereby obtaining the corrected heat transfer oil flow rate; based on historical operating data of the load deviation and molten salt pump frequency of the parabolic trough solar thermal power plant, a second empirical function relating the load deviation and molten salt pump frequency is obtained through function fitting, where the load deviation is the difference between the target load and the actual load; Based on the first correction function and the second empirical function, and combined with the current target load, the corrected heat transfer oil flow rate and the hot molten salt pump frequency are obtained, and the heat transfer oil pump and the hot molten salt pump are adjusted to achieve matching. The formula for the first correction function is as follows: F1(x)=(90.74-Δ)×y+y; where F1 is the corrected heat transfer oil flow rate, Δ is the temperature difference between the hot end of the heat transfer oil at the evaporator inlet and the hot end of the heat transfer oil at the evaporator outlet, x is the target load, and y is the heat transfer oil flow rate.
2. The coordinated control method according to claim 1, characterized in that, When the steam turbine generator is in sliding pressure operation, the regulating valve of the steam turbine generator is fully open or the opening degree remains unchanged to keep the main steam temperature basically unchanged, and the output load is adjusted by the heat transfer oil to regulate the main steam flow and pressure.
3. The coordinated control method according to claim 1, characterized in that, The target load of the parabolic trough solar thermal power plant fluctuates according to the grid AGC control requirements, thereby adjusting the heat transfer oil pump and the hot molten salt pump accordingly.
4. The coordinated control method according to claim 1, characterized in that, In the heat release mode, the thermal storage system of the parabolic trough solar thermal power plant heats water into steam through the hot salt tank of the thermal storage system to promote the operation of the steam turbine generator.
5. The coordinated control method according to claim 1, characterized in that, The parabolic trough solar thermal power plant also includes a concentrating collector, a hot oil manifold, a cold oil manifold, a heating furnace, a first regulating valve, and a second regulating valve. The concentrating collector, the hot oil manifold, the first regulating valve, the heating furnace, the second regulating valve, the thermal oil pump, and the cold oil manifold are connected in sequence to form a circuit. The first regulating valve is used to automatically regulate the pressure of the thermal oil header, and the second regulating valve is used to automatically regulate the inlet temperature of the thermal oil entering the thermal oil pump.
6. The coordinated control method according to claim 1, characterized in that, The parabolic trough solar thermal power plant also includes an outlet regulating valve, which is located between the molten salt pump and the oil-salt heat exchanger and is used to automatically regulate the outlet pressure of the molten salt pump.
7. The coordinated control method according to claim 1, characterized in that, After receiving the load command, the parabolic trough solar thermal power plant obtains the target load by performing frequency regulation, speed limiting, and amplitude limiting, and then calculates the heat transfer oil flow rate through the first correction function.
8. The coordinated control method according to claim 1, characterized in that, The thermal oil flow rate, thermal oil pump main pipe pressure, thermal oil pump inlet temperature, and hot molten salt pump outlet pressure are all regulated by single-impulse PID control.
9. The coordinated control method according to claim 1, characterized in that, The outlet temperature of the heat transfer oil in the oil-salt heat exchanger is controlled by a single-impulse PID controller.