阅读说明：本技术 一种核电站直流式蒸汽发生器出口温度控制方法 (Method for controlling outlet temperature of direct-flow steam generator of nuclear power station ) 是由 刘俊峰 马晓珑 韩传高 张瑞祥 宋健 姚尧 武方杰 孙文钊 于 2020-11-20 设计创作，主要内容包括：本发明公开了一种核电站直流式蒸汽发生器出口温度控制方法,包括以下步骤：1)获取蒸汽发生器出口温度设定值,同时获取当前蒸汽发生器出口温度测量值、冷却剂流量测量值及给水流量测量值；2)确定蒸汽发生器出口的冷却剂流量设定值及给水流量设定值；3)得冷却剂泵或风机变频器频率的设定值；4)得给水泵变频器频率的设定值；5)根据冷却剂泵或风机变频器频率的设定值调节冷却剂泵或风机的转速；根据给水泵变频器频率的设定值调节给水泵转速,以控制蒸汽发生器出口蒸汽温度,该方法能够有效提高核电站直流式蒸汽发生器出口温度控制的稳定性和灵活性。(The invention discloses a method for controlling the outlet temperature of a straight-flow steam generator of a nuclear power station, which comprises the following steps: 1) acquiring a set value of outlet temperature of the steam generator, and simultaneously acquiring a current measured value of outlet temperature of the steam generator, a measured value of coolant flow and a measured value of water supply flow; 2) determining a coolant flow set value and a water supply flow set value of an outlet of the steam generator; 3) obtaining a set value of the frequency of a coolant pump or a fan frequency converter; 4) obtaining a set value of the frequency converter of the water feeding pump; 5) adjusting the rotating speed of the coolant pump or the fan according to the set value of the frequency of the coolant pump or the fan frequency converter; the rotating speed of the feed pump is adjusted according to the set value of the frequency converter of the feed pump so as to control the temperature of steam at the outlet of the steam generator.)

1. The method for controlling the outlet temperature of the straight-flow steam generator of the nuclear power plant is characterized by comprising the following steps of:

1) acquiring a set value of outlet temperature of the steam generator, and simultaneously acquiring a current measured value of outlet temperature of the steam generator, a measured value of coolant flow and a measured value of water supply flow;

2) calculating the temperature deviation between a set value of the outlet temperature of the steam generator and a measured value of the outlet temperature of the steam generator, and then determining a set value of the coolant flow and a set value of the water supply flow of the outlet of the steam generator by using a temperature controller of the outlet of the steam generator according to the temperature deviation;

3) calculating the coolant flow deviation between the coolant flow measurement value and the coolant flow set value, inputting the coolant flow deviation into the coolant flow controller, and superposing the frequency signal of the coolant pump or the fan output by the coolant flow controller on the flow-rotating speed feedforward signal of the coolant pump or the fan to obtain the set value of the frequency of the coolant pump or the fan frequency converter;

4) calculating a water supply flow deviation according to a water supply flow set value and a water supply flow measured value, inputting the water supply flow deviation into a water supply flow controller, and superposing a frequency signal of a water supply pump output by the water supply flow controller on a water supply pump flow-rotating speed feedforward signal to obtain a set value of the frequency of a frequency converter of the water supply pump;

5) adjusting the rotating speed of the coolant pump or the fan according to the set value of the frequency of the coolant pump or the fan frequency converter; and adjusting the rotating speed of the water feeding pump according to the set value of the frequency converter of the water feeding pump so as to control the temperature of the steam at the outlet of the steam generator.

2. The method for controlling outlet temperature of once-through steam generator of nuclear power plant according to claim 1, further comprising: the flow-speed feed-forward signal of the coolant pump or the fan is detected by a coolant pump or a fan flow-speed meter.

3. The method for controlling outlet temperature of once-through steam generator of nuclear power plant according to claim 1, further comprising: and detecting a feed-forward signal of the flow-rotating speed of the feed pump through a flow-rotating speed meter of the feed pump.

Technical Field

The invention belongs to the field of nuclear power science and engineering, and relates to a method for controlling the outlet temperature of a direct-flow steam generator of a nuclear power station.

Background

The nuclear power plant steam generator outlet temperature is one of the most important control variables in the operation of the nuclear power plant. In the process of starting, normally operating and lifting load of a nuclear power unit, the temperature of an outlet of a steam generator is influenced by various factors, and the method mainly comprises the following steps: reactor power, primary loop coolant flow, feedwater temperature, feedwater flow, desuperheating water flow and temperature, and the like. In the running process of the straight-flow steam generator of the nuclear power station, the secondary side water capacity and the heat capacity are both very small, the buffering capacity is very limited, and the control of the feedwater flow is adjusted by maintaining the main steam pressure unchanged. Because the main steam temperature change is very sensitive to the influence of pressure disturbance, the direct current steam generator needs to realize dynamic balance in the dynamic process, and has high requirements on an outlet steam temperature control system. If the temperature of the main steam is not well controlled, the heat transfer pipe of the steam generator can be damaged due to long-time high-temperature operation, pipe explosion can be caused under severe conditions, the service life of the steam turbine can be shortened due to the side of the steam turbine, and parts such as a cylinder, a blade, a front bearing of a high-pressure cylinder and the like are damaged. Similarly, the main steam with too low temperature for a long time can cause unit safety problems, which can cause thermal fatigue of turbine parts, and the expansion difference of the cylinder and the rotor, etc. to deviate from the normal operation condition.

Due to the complexity of steam generator outlet temperature control, control of the main steam temperature has been a difficult point in the nuclear power plant operation process. For a nuclear power unit adopting a straight-flow steam generator, such as a high-temperature gas cooled reactor, a sodium cooled fast reactor and the like, the control of the outlet temperature of the steam generator at the present stage is realized by adopting a scheme of regulating the flow of a coolant. The specific control principle is shown in fig. 1 below. The existing steam generator outlet temperature control scheme is cascade control, and the actuator is a coolant pump or a fan. The steam generator outlet temperature control system is used as a main loop of the cascade control loop, and the coolant flow control system is used as a secondary loop of the cascade control loop. For a high temperature gas cooled reactor, the coolant is primary loop helium; for a sodium-cooled fast reactor, the coolant is sodium. The steam generator outlet temperature adopts a cascade control mode, and compared with single-loop control, the steam generator outlet temperature has the advantages of reducing the maximum deviation and integral error of a control variable, but at least has the following technical defects: (1) the cascade control loop is based on the assumed condition that the disturbance of the control variable obeys Gaussian distribution, the control precision is relatively high, but the control of the outlet temperature of the direct-flow steam generator of the nuclear power station is complex, and the disturbance does not completely accord with the Gaussian distribution, so that the flexibility of the single cascade control loop is poor. Particularly, when the unit operates under variable working conditions, the control loop is difficult to dynamically and accurately track parameter changes; (2) when the coolant flow control system for controlling the outlet temperature of the steam generator has an abnormal fault, the single cascade control loop loses the control function, the outlet temperature of the steam generator is changed rapidly, abnormal events such as reactor tripping and the like are easily caused, and the stability is poor.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for controlling the outlet temperature of a once-through steam generator of a nuclear power station, which can effectively improve the stability and flexibility of the outlet temperature control of the once-through steam generator of the nuclear power station.

In order to achieve the purpose, the method for controlling the outlet temperature of the straight-flow steam generator of the nuclear power station comprises the following steps:

1) acquiring a set value of outlet temperature of the steam generator, and simultaneously acquiring a current measured value of outlet temperature of the steam generator, a measured value of coolant flow and a measured value of water supply flow;

2) calculating the temperature deviation between a set value of the outlet temperature of the steam generator and a measured value of the outlet temperature of the steam generator, and then determining a set value of the coolant flow and a set value of the water supply flow of the outlet of the steam generator by using a temperature controller of the outlet of the steam generator according to the temperature deviation;

3) calculating the coolant flow deviation between the coolant flow measurement value and the coolant flow set value, inputting the coolant flow deviation into the coolant flow controller, and superposing the frequency signal of the coolant pump or the fan output by the coolant flow controller on the flow-rotating speed feedforward signal of the coolant pump or the fan to obtain the set value of the frequency of the coolant pump or the fan frequency converter;

4) calculating a water supply flow deviation according to a water supply flow set value and a water supply flow measured value, inputting the water supply flow deviation into a water supply flow controller, and superposing a frequency signal of a water supply pump output by the water supply flow controller on a water supply pump flow-rotating speed feedforward signal to obtain a set value of the frequency of a frequency converter of the water supply pump;

5) adjusting the rotating speed of the coolant pump or the fan according to the set value of the frequency of the coolant pump or the fan frequency converter; and adjusting the rotating speed of the water feeding pump according to the set value of the frequency converter of the water feeding pump so as to control the temperature of the steam at the outlet of the steam generator.

Further comprising: the flow-speed feed-forward signal of the coolant pump or the fan is detected by a coolant pump or a fan flow-speed meter.

Further comprising: and detecting a feed-forward signal of the flow-rotating speed of the feed pump through a flow-rotating speed meter of the feed pump.

The invention has the following beneficial effects:

when the method for controlling the outlet temperature of the once-through steam generator of the nuclear power plant is operated specifically, determining a set value of coolant flow and a set value of feedwater flow at the outlet of the steam generator according to a temperature deviation between a set value of outlet temperature of the steam generator and a measured value of outlet temperature of the steam generator, determining a set value of frequency of a frequency converter of a coolant pump or a fan according to a coolant flow deviation between the measured value of coolant flow and the set value of coolant flow, meanwhile, the set value of the frequency converter of the water feeding pump is determined according to the water flow deviation between the set value of the water feeding flow and the measured value of the water feeding flow, meanwhile, the feedforward signal is comprehensively considered in the determination process, and the rotating speed of a coolant pump or a fan and the outlet steam temperature of the steam generator are controlled according to the feedforward signal, so that the stability and flexibility of the outlet temperature control of the straight-flow steam generator of the nuclear power station are improved.

Drawings

FIG. 1 is a schematic diagram of outlet temperature control of a once-through steam generator of a nuclear power plant;

FIG. 2 is a schematic diagram of a process system according to the present invention;

FIG. 3 is a control schematic of the present invention;

FIG. 4 is a control flow diagram of the present invention;

FIG. 5 is a flow chart of the control algorithm of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

referring to FIG. 2, a process system includes a reactor, control rods, coolant pumps or fans, steam generators, feedwater pumps, and a main steam supply system; the associated control loops include a reactor power controller, a coolant flow controller, a feedwater flow controller, and a steam generator outlet temperature controller.

Referring to fig. 3, the steam generator outlet temperature control adopts a parallel cascade control loop, the outer loop of the control loop is the steam generator outlet temperature control, and the coolant flow set value and the feed water flow set value are calculated by the steam generator outlet temperature controller according to the steam generator outlet temperature set value and the measured value; the inner ring of the control loop comprises coolant flow control and water supply flow control, and the coolant flow and the water supply flow adopt a parallel control mode, participate in outlet temperature control of the steam generator and are mutually standby.

Specifically, the method for controlling the outlet temperature of the straight-flow steam generator of the nuclear power station comprises the following steps:

1) acquiring a set value of outlet temperature of the steam generator, and simultaneously acquiring a current measured value of outlet temperature of the steam generator, a measured value of coolant flow and a measured value of water supply flow;

2) calculating the temperature deviation between a set value of the outlet temperature of the steam generator and a measured value of the outlet temperature of the steam generator, and then determining a set value of the coolant flow and a set value of the water supply flow of the outlet of the steam generator by using a temperature controller of the outlet of the steam generator according to the temperature deviation;

3) calculating the coolant flow deviation between the coolant flow measurement value and the coolant flow set value, inputting the coolant flow deviation into the coolant flow controller, and superposing the frequency signal of the coolant pump or the fan output by the coolant flow controller on the flow-rotating speed feedforward signal of the coolant pump or the fan to obtain the set value of the frequency of the coolant pump or the fan frequency converter;

4) calculating a water supply flow deviation according to a water supply flow set value and a water supply flow measured value, inputting the water supply flow deviation into a water supply flow controller, and superposing a frequency signal of a water supply pump output by the water supply flow controller on a water supply pump flow-rotating speed feedforward signal to obtain a set value of the frequency of a frequency converter of the water supply pump;

5) adjusting the rotating speed of the coolant pump or the fan according to the set value of the frequency of the coolant pump or the fan frequency converter; and adjusting the rotating speed of the water feeding pump according to the set value of the frequency converter of the water feeding pump so as to control the temperature of the steam at the outlet of the steam generator.

Detecting a flow-speed feed-forward signal of the coolant pump or the fan through a coolant pump or a fan flow-speed meter; and detecting a feed-forward signal of the flow-rotating speed of the feed pump through a flow-rotating speed meter of the feed pump.

The above control algorithm is given by fig. 5, and a proportional integral algorithm is selected, and the control target is to make the steam generator outlet temperature deviation zero or less than the deviation threshold.

Example one

In this embodiment, a nuclear power generating unit of a high temperature gas cooled reactor is taken as an example, a steam generator of the nuclear power generating unit of the high temperature gas cooled reactor is of a vertical and direct current coil tube assembly type structure, a coolant of a primary loop is helium gas, a coolant driving mechanism is a main helium fan, and a steam generator outlet temperature control process system includes a reactor, a control rod, a main helium fan, a steam generator, a water feed pump and a main steam supply system; the process system control loop includes a reactor power controller, a helium flow controller, a feedwater flow controller, and a main steam temperature controller.

The outlet temperature control of the steam generator adopts a parallel cascade control loop, the outer ring of the control loop is used for controlling the outlet temperature of the steam generator, and the helium flow and the feed water flow set value are calculated by a steam generator outlet temperature controller according to the set value and the measured value of the outlet temperature of the steam generator; the inner ring of the control loop comprises helium flow control and water supply flow control, the helium flow and the water supply flow adopt a parallel control mode, the outlet temperature of the steam generator is controlled by adjusting the rotating speed of the main helium fan and the water supply pump, and the two parallel control loops are mutually standby.

During the normal operation of the high-temperature gas cooled reactor, the helium flow controller and the feed water flow controller simultaneously participate in the steam temperature control at the outlet of the steam generator, and the control flow shown in fig. 2, 3, 4 and 5 reaches the following operation criteria: the steam temperature overshoot at the outlet of the steam generator is less than 5 ℃, the steady state deviation is less than 2.5 ℃, the helium flow regulation time is less than 500s, the feedwater flow regulation time is less than 200s, and the nuclear power regulation time is less than 500 s.

When the helium flow controller of the high-temperature gas cooled reactor is abnormal, the helium flow controller is cut off, the water supply flow controller responds quickly, and the steam temperature at the outlet of the steam generator is controlled to meet the requirement of abnormal operation working conditions.

When the high-temperature gas cooled reactor water supply flow controller is abnormal, the water supply flow controller is cut off, the helium flow controller responds quickly, and the steam temperature at the outlet of the steam generator is controlled to meet the requirement of abnormal operation working conditions.

Example two

In this embodiment, a sodium-cooled fast reactor unit is taken as an example, a sodium-cooled fast reactor steam generator is of a vertical and straight-flow structure, a first loop coolant and a second loop coolant are sodium, a coolant driving mechanism is a sodium circulating pump, and a steam generator outlet temperature control process system includes a reactor, a control rod, a primary sodium circulating pump, a secondary sodium circulating pump, a steam generator, a water feed pump and a main steam supply system; the process system control loop comprises a reactor power control system, a sodium flow controller, a feedwater flow controller and a main steam temperature controller.

The outlet temperature control of the steam generator adopts a parallel cascade control loop. The outer ring of the control loop is used for controlling the outlet temperature of the steam generator, and the primary and secondary side sodium flow and the feedwater flow set value are obtained through calculation of the outlet temperature controller of the steam generator according to the outlet temperature set value and the measured value of the steam generator; the inner ring of the control loop comprises sodium flow control and water supply flow control, the sodium flow and the water supply flow adopt a parallel control mode, the outlet temperature of the steam generator is controlled by adjusting the rotating speed of a sodium circulating pump and a water supply pump, and the two parallel control loops are mutually standby.

During the normal operation of the sodium-cooled fast reactor, the sodium flow controller and the feed water flow controller simultaneously participate in the steam generator outlet steam temperature control, and the control flow shown in fig. 2, 3, 4 and 5 reaches the following operation criteria: the steam temperature overshoot at the outlet of the steam generator is less than 5 ℃, and the steady state deviation is less than 2.5 ℃. The sodium flow regulation time is less than 500s, the water supply flow regulation time is less than 200s, and the nuclear power regulation time is less than 500 s.

When the sodium flow controllers on the primary side and the secondary side of the sodium-cooled fast reactor are abnormal, the sodium flow controllers are cut off, the water supply flow controllers respond quickly, and the steam temperature at the outlet of the steam generator is controlled to meet the requirement of abnormal operation working conditions.

When the sodium-cooled fast reactor water supply flow controller is abnormal, the water supply flow controller is cut off, the sodium flow controller responds quickly, and the steam temperature at the outlet of the steam generator is controlled to meet the requirement of abnormal operation working conditions.

Compared with the original cascade control loop, the control loop has more control stability and accuracy for non-Gaussian distributed control variable disturbance, is more suitable for controlling the outlet temperature of the direct-flow steam generator of the nuclear power station, and can track parameter change in time particularly when a unit operates under variable working conditions;

in addition, the parallel cascade control loops are adopted, compared with the original single cascade control loop, the coolant flow control system and the feed water flow control system are mutually standby, when any control loop has an abnormal fault, the other control loop can be put into use in time, the probability of reactor safety accidents caused by failure of the original single cascade control loop can be greatly reduced, the stability and flexibility of control loop regulation in a reactor variable working condition operation mode are improved, and a control idea is provided for the subsequent participation of a nuclear power unit in power grid peak regulation and frequency modulation.