Patent Description:
A once-through steam generator is a key device in the reactor design, which provides sufficient water for the steam generator to transfer heat in the primary loop coolant, causing the steam generator to generate and supply saturated steam to the secondary loop powerplant. In the design of the PWR nuclear power plant, the pressure of the steam generator is controlled to be near its design value by an automatic pressure control system of the once-through steam generator, thereby ensuring the normal and stable operation of the reactor.

In the prior art, the outlet pressure of the once-through steam generator is usually controlled by using pressure deviation and steam-water flow deviation, without considering mismatching between the quick response characteristic of the once-through steam generator and the response lag of the reactor core.

The disadvantages of the prior art include high requirements for the execution mechanism of the control system and large amplitude of the valve action, which are adverse to the system stability.

Publications <CIT>, <CIT>, <CIT> and <CIT> are considered to be relevant to the present application.

The technical problem to be solved by the present invention is to provide an improved steam generator system, steam generator pressure control system and steam generator pressure control method, which can meet the requirements of the outlet pressure control of the once-through steam generator and ensure the normal and stable operation of the once-through steam generator.

The technical solution adopted by the present invention to solve the technical problem is providing a once-through steam generator pressure control system comprising a once-through steam generator, a steam turbine and a water supply regulating valve group. The system further includes:.

Preferably, the high-low load signal includes coarse adjustment opening data, and a first valve opening is further set for the first valve according to the coarse adjustment opening data.

Preferably, the fine adjustment control signal includes fine adjustment opening data, and a second valve opening is further set for the second valve according to the fine adjustment opening data in the fine adjustment control signal.

Preferably, the system further includes a pressure control device, and the pressure control device includes the first control unit, the second control unit and the third control unit.

Preferably, the steam-water flow deviation control channel includes a first steam-water flow deviation control channel and a second steam-water flow deviation control channel, the first steam-water flow deviation control channel is configured to measure the outlet flow value of the once-through steam generator, and the second steam-water flow deviation control channel is configured to measure the inlet flow value of the water supply regulating valve group; the first steam-water flow deviation control channel includes a second pressure transmitter, a second analog quantity conditioning distribution board and a second analog quantity input board.

Preferably, the pressure deviation control channel includes a first pressure transmitter, a first analog quantity conditioning distribution board, and a first analog quantity input board.

Preferably, the load demand control channel includes a third pressure transmitter, a third analog quantity conditioning distribution board, and a third analog quantity input board.

A once-through steam generator pressure control method is also provided, which includes the following steps executed by the above-described once-through steam generator pressure control system:.

Preferably, the high-low load signal further includes coarse adjustment opening data, and the method further includes the step of setting a first valve opening for the first valve according to the coarse adjustment opening data.

Preferably, the fine adjustment control signal includes fine adjustment opening data, and the method further includes the step of setting a second valve opening for the second valve according to the fine adjustment opening data in the fine adjustment control signal.

A steam generator pressure control system is also provided, which includes:.

Preferably, the second opening degree value of the second valve includes second opening data, and a first valve opening is further set for the first valve according to the second opening data.

Preferably, the first opening degree value of the first valve includes first opening data, and a second valve opening is further set for the second valve according to the first opening data.

Preferably, the first control module includes a first control channel and a first control unit, the first control channel is configured to measure the outlet pressure value of the steam generator, and the first control unit is configured to compare the outlet pressure value with the preset target pressure value to obtain the pressure deviation value.

Preferably, the second control module includes a second control channel and a second control unit, the second control channel is configured to measure the outlet flow value of the steam generator and the inlet flow value of the water supply regulating valve group, the second control unit is configured to calculate the flow difference value between the outlet flow value and the inlet flow value, and then superposing the flow difference value and the pressure deviation value.

Preferably, the second control channel includes a first deviation control channel and a second deviation control channel, the first deviation control channel is configured to measure the outlet flow value of the steam generator, and the second deviation control channel is configured to measure the inlet flow value of the water supply regulating valve group.

Preferably, the third control module includes a third control channel and a third control unit, the third control channel is configured to measure the steam inlet pressure value of the steam turbine, and the third control unit is configured to compare the steam inlet pressure value with the preset reference threshold to obtain the second opening degree value for controlling the second valve of the water supply regulating valve group.

A steam generator pressure control method is also provided, which includes:.

A nuclear power plant steam generator system is also provided, which includes a steam generator, a steam turbine, a water supply regulating valve group, and the above-described steam generator pressure control system.

The present invention has the following benefits. In the steam generator system, the steam generator pressure control system and the steam generator pressure control method, the steam generator pressure control system controls the opening and closing conditions of the water supply regulating valve group through the first control module, the second control module and the third control module. The three control modules are used to distinguish the needs of coarse adjustment and fine adjustment so as to individually control the opening and closing conditions of the first valve and the second valve, thereby meeting the needs of both the coarse adjustment and the fine adjustment.

According to the steam generator system, the steam generator pressure control system and the steam generator control method, the once-through steam generator cannot only achieve the fine adjustment of the pressure in the small-disturbance transient process, but can also quickly and stably adjust the pressure to the target state when a large-amplitude transient change occurs.

In the normal operation transient process of the reactor, the present invention can quickly and accurately control the outlet pressure of the once-through steam generator, with the mismatching between the rapid response characteristic of the once-through steam generator and the response lag of the reactor core being also taken into account, thereby realizing coordinated control of the primary and secondary loops, such that the response of the control system and actions of the executing mechanism are made more reasonable, which is beneficial to the stable operation of the reactor system.

The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:.

In order to provide a better understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are described in detail with reference to the accompanying drawings.

<FIG> shows a once-through steam generator pressure control system according to some embodiments of the present invention, for controlling a once-through steam generator <NUM>, which can not only achieve fine adjustment of pressure in a small disturbance transient process, but can also quickly and stably adjust the pressure to a target state when a large-amplitude transient change occurs. As shown in <FIG>, the once-through steam generator pressure control system according to the embodiments of the present invention incudes a once-through steam generator <NUM>, a steam turbine <NUM>, a water supply regulating valve group <NUM>, a pressure deviation control channel <NUM>, a steam-water flow deviation control channel <NUM>, a load demand control channel <NUM>, and a pressure control device <NUM>. The pressure deviation control channel <NUM>, the steam-water flow deviation control channel <NUM> and the load demand control channel <NUM> respectively measure an outlet pressure value, an outlet flow value,an inlet flow value, and a steam inlet pressure value, and the pressure control device <NUM> calculates and distinguishes a coarse adjustment state and a fine adjustment state according to the outlet pressure value, the outlet flow value, the inlet flow value and the steam inlet pressure value, and outputs a fine adjustment control signal and high-low load signal, so as to control opening and closing conditions of the water supply regulating valve group <NUM>.

The pressure deviation control channel <NUM> is configured to measure the outlet pressure value of the once-through steam generator <NUM>. An inlet of the pressure deviation control channel <NUM> is connected to an outlet of the once-through steam generator <NUM>, and an outlet of the pressure deviation control channel <NUM> is connected to the pressure control device <NUM>. In some embodiments, as an option, the pressure deviation control channel <NUM> may include a first pressure transmitter, a first analog quantity conditioning distribution board, and a first analog quantity input board. It can be understood that the pressure measurement, the analog quantity conditioning and input of the pressure deviation control channel <NUM> may also be performed in other manners, which are not specifically limited herein, as long as relevant functions can be achieved.

As shown in <FIG> and <FIG>, the steam-water flow deviation control channel <NUM> is configured to measure the outlet flow value of the once-through steam generator <NUM> and the inlet flow value of the water supply regulating valve group <NUM>. In some embodiments, the steam-water flow deviation control channel <NUM> includes a first steam-water flow deviation control channel <NUM> and a second steam-water flow deviation control channel <NUM>, the first steam-water flow deviation control channel <NUM> is configured to measure the outlet flow value of the once-through steam generator <NUM>, and the second steam-water flow deviation control channel <NUM> is configured to measure the inlet flow value of the water supply regulating valve group <NUM>. In some embodiments, as an option, the first steam-water flow deviation control channel <NUM> may include a second pressure transmitter, a second analog quantity conditioning distribution board, and a second analog quantity input board. It can be understood that the pressure measurement, the analog quantity conditioning and input of the steam-water flow deviation control channel <NUM> may also be performed in other manners, which are not specifically limited herein, as long as relevant functions can be achieved.

The load demand control channel <NUM> is configured to measure the steam inlet pressure value of the steam turbine <NUM>. An inlet of the load demand control channel <NUM> is connected to an inlet of the steam turbine <NUM>, and an outlet of the load demand control channel <NUM> is connected to the pressure control device <NUM>. As an option, in some embodiments, the load demand control channel <NUM> may include a third pressure transmitter, a third analog quantity conditioning distribution board, and a third analog quantity input board. It can be understood that the pressure measurement, the analog quantity conditioning and input of the load demand control channel <NUM> may also be performed in other manners, which are not specifically limited herein, as long as relevant functions can be achieved.

As shown in <FIG>, the pressure control device <NUM> includes a first control unit <NUM>, a second control unit <NUM>, and a third control unit <NUM>. It can be understood that the first control unit <NUM>, the second control unit <NUM>, and the third control unit <NUM> may be implemented as software or circuit boards, which is not limited herein, as long as relevant functions can be achieved.

The first control unit <NUM> is configured to compare the outlet pressure value with a target pressure setting value and selectively output a pressure deviation signal. It can be understood that the target pressure setting value herein may be set according to specific requirements, which is not specifically limited herein, as long as relevant functions can be achieved.

The second control unit <NUM> calculates a difference value between the outlet flow value and the inlet flow value, superimposes the difference value and the pressure deviation signal, and outputs a fine adjustment control signal. Preferably, the fine adjustment control signal includes fine adjustment opening data.

The third control unit <NUM> is configured to compare the steam inlet pressure value with a switching threshold and selectively output a high-low load signal. Preferably, the high-low load signal includes coarse adjustment opening data.

The water supply regulating valve group <NUM> includes a first valve <NUM> and a second valve <NUM>, the first valve <NUM> is selectively opened or closed according to the high-low load signal, and the second valve <NUM> is selectively opened or closed according to the high-low load signal.

In some embodiments, a first valve opening is further set for the first valve <NUM> according to the coarse adjustment opening data. A second valve opening is further set for the second valve <NUM> according to the fine adjustment opening data in the fine adjustment control signal.

<FIG> illustrates a steam generator system of a nuclear power plant according to other embodiments of the present invention, which includes a steam generator <NUM>, a steam turbine <NUM>, a water supply regulating valve group <NUM>, and a steam generator pressure control system <NUM>. As shown in <FIG>, <FIG> and <FIG>, the water supply regulating valve group <NUM> includes a first valve <NUM> and a second valve <NUM>; the steam generator pressure control system <NUM> includes a first control module <NUM>, a second control module <NUM> and a third control module <NUM>, the first control module <NUM> is configured to obtain a pressure deviation value, the second control module <NUM> is configured to obtain a first opening degree value for controlling the first valve <NUM> of the water supply regulating valve group <NUM>, and the third control module <NUM> is configured to obtain a second opening degree value for controlling the second valve <NUM> of the water supply regulating valve group <NUM>. The steam generator pressure control system <NUM> controls the opening and closing conditions of the water supply regulating valve group <NUM> through the first control module <NUM>, the second control module <NUM> and the third control module <NUM>, so as to control the steam generator <NUM>, which can not only achieve the fine adjustment of the pressure in the small disturbance transient process, but can also quickly and stably adjust the pressure to the target state when a large-amplitude transient change occurs.

In some embodiments, the steam generator <NUM> may be a once-through steam generator, or may be a steam generator in other common forms in the nuclear power field, which is not specifically limited herein, as long as relevant functions can be achieved. The steam turbine <NUM> may be the same as those in the foregoing embodiment, and may also be a steam turbine <NUM> in other common forms in the nuclear power field, which is not specifically limited herein, as long as relevant functions can be achieved.

As shown in <FIG>, <FIG> and <FIG>, the water supply regulating valve group <NUM> includes a first valve <NUM> and a second valve <NUM>, the first valve <NUM> is selectively opened or closed according to the first opening degree value, and the second valve <NUM> is selectively opened or closed according to the second opening degree value.

In some embodiments, the first valve <NUM> further sets the first valve opening according to the second opening data in the second opening degree value. The second valve <NUM> further sets the second valve opening according to the first opening data in the first opening degree value. Preferably, the first opening degree value of the first valve <NUM> includes first opening data, and the second valve <NUM> further sets the second valve opening according to the first opening data.

Referring to <FIG>, <FIG> and <FIG>, in some preferred embodiments of the present invention, the steam generator pressure control system <NUM> includes a first control module <NUM>, a second control module <NUM>, and a third control module <NUM>. The first control module <NUM> is configured to obtain a pressure deviation value, the second control module <NUM> is configured to obtain a first opening degree value for controlling the first valve <NUM> of the water supply regulating valve group <NUM>, and the third control module <NUM> is configured to obtain a second opening degree value for controlling the second valve <NUM> of the water supply regulating valve group <NUM>.

Referring to <FIG> and <FIG>, the first control module <NUM> is configured to measure the outlet pressure value of the steam generator <NUM>, and compare the outlet pressure value with a preset target pressure value to obtain a pressure deviation value. Specifically, the first control module <NUM> includes a first control channel <NUM> and a first control unit <NUM>, the first control channel <NUM> is configured to measure the outlet pressure value of the steam generator <NUM>, and the first control unit <NUM> is configured to compare the outlet pressure value with the preset target pressure value to obtain a pressure deviation value.

Referring to <FIG>, <FIG>, <FIG> and <FIG>, the second control module <NUM> is configured to measure the outlet flow value of the steam generator <NUM> and the inlet flow value of the water supply regulating valve group <NUM>, calculate a flow difference value between the outlet flow value and the inlet flow value, and superimpose the flow difference value and the pressure deviation value to obtain a first opening degree value for controlling the first valve <NUM> of the water supply regulating valve group <NUM>. Preferably, the first opening degree value of the first valve <NUM> includes first opening data, and a second valve opening is further set for the second valve <NUM> according to the first opening data.

Specifically, the second control module <NUM> includes a second control channel <NUM> and a second control unit <NUM>, the second control channel <NUM> is configured to measure the outlet flow value of the steam generator <NUM> and the inlet flow value of the water supply regulating valve group <NUM>, the second control unit <NUM> is configured to calculate a flow difference value between the outlet flow value and the inlet flow value, and then superimpose the flow difference value and the pressure deviation value.

In some embodiments, the second control channel <NUM> includes a first deviation control channel <NUM> and a second deviation control channel <NUM>, the first deviation control channel <NUM> is configured to measure the outlet flow value of the steam generator <NUM>, and the second deviation control channel <NUM> is configured to measure the inlet flow value of the water supply regulating valve group <NUM>.

Referring to <FIG>, <FIG>, <FIG> and <FIG>, the third control module <NUM> is configured to measure the steam inlet pressure value of the steam turbine <NUM>, and compare the steam inlet pressure value with a preset reference threshold to obtain a second opening degree value for controlling the second valve <NUM> of the water supply regulating valve group <NUM>. Preferably, the second opening degree value of the second valve <NUM> includes second opening data, and a first valve opening is further set for the first valve <NUM> according to the second opening data.

Specifically, the third control module <NUM> includes a third control channel <NUM> and a third control unit <NUM>, the third control channel <NUM> is configured to measure the steam inlet pressure value of the steam turbine <NUM>, and the third control unit <NUM> is configured to compare the steam inlet pressure value with a preset reference threshold to obtain a second opening degree value for controlling the second valve <NUM> of the water supply regulating valve group <NUM>.

Other parts of the nuclear power plant steam generator system in this embodiment are the same as the once-through steam generator pressure control system in the foregoing embodiment, explanations of which are not repeated herein.

The specific steps of the once-through steam generator pressure control method according to some embodiments of the present invention are described below with reference to <FIG>. In the embodiments of the present invention, the once-through steam generator pressure control method includes the following steps S1-S3.

S1: measuring an outlet pressure value of the once-through steam generator <NUM>, determining whether the outlet pressure value is greater than a target pressure setting value, and if yes, outputting a pressure deviation signal.

S2: measuring an outlet flow value of the once-through steam generator <NUM> and an inlet flow value of the water supply regulating valve group <NUM>, calculating a difference value between the outlet flow value and the inlet flow value, superposing the difference value and the pressure deviation signal, and outputting a fine adjustment control signal.

S3: measuring a steam inlet pressure value of the steam turbine <NUM>, determining whether the steam inlet pressure value exceeds a switching threshold value or not, if yes, outputting a high-low load signal, and opening both the first valve <NUM> and the second valve <NUM>; and if not, closing the first valve <NUM>, and opening the second valve <NUM>.

In some embodiments, the high-low load signal further includes coarse adjustment opening data, and the method further includes the step that a first valve opening is further set for the first valve <NUM> according to the coarse adjustment opening data. Preferably, a second valve opening is further set for the second valve <NUM> according to the fine adjustment opening data in the fine adjustment control signal.

The once-through steam generator pressure control method of this embodiment is consistent with the once-through steam generator pressure control system in the foregoing embodiment, explanations of which are not repeated herein.

The specific steps of the steam generator pressure control method in some preferred embodiments of the present invention are described below in conjunction with <FIG>. In this embodiment, the steam generator pressure control method further includes the following steps S1-S3:.

Preferably, step S21 further includes step S211 and step S212:.

S3: measuring a steam inlet pressure value of the steam turbine <NUM>, and comparing the steam inlet pressure value with a preset reference threshold to obtain a second opening degree value for controlling the second valve <NUM> of the water supply regulating valve group <NUM>.

Preferably, step S3 further includes step S31 and step S32:.

In some other embodiments, the present invention further provides a steam generator pressure control system <NUM> as shown in <FIG>. The steam generator pressure control system <NUM> of this embodiment is consistent with those in the foregoing embodiment, details of which are not repeated herein. The once-through steam generator pressure control method and system enables the once-through steam generator <NUM> to not only achieve the fine adjustment of the pressure in the small disturbance transient process, but also quickly and stably adjust the pressure to the target state when a large-amplitude transient change occurs.

Claim 1:
A once-through steam generator pressure control system, comprising a once-through steam generator (<NUM>), a steam turbine (<NUM>) and a water supply regulating valve group (<NUM>); the system further comprising
a pressure deviation control channel (<NUM>) configured to measure an outlet pressure value of the once-through steam generator (<NUM>);
a first control unit (<NUM>) configured to compare the outlet pressure value with a target pressure setting value and selectively output a pressure deviation signal;
a steam-water flow deviation control channel (<NUM>) configured to measure an outlet flow value of the once-through steam generator (<NUM>) and an inlet flow value of the water supply regulating valve group (<NUM>);
a second control unit (<NUM>) configured to calculate a difference value between the outlet flow value and the inlet flow value, superpose the difference value and the pressure deviation signal, and output a fine adjustment control signal;
characterized in that it further comprises
a load demand control channel (<NUM>) configured to measure a steam inlet pressure value of the steam turbine (<NUM>);
a third control unit (<NUM>) configured to compare the steam inlet pressure value with a switching threshold value and selectively output a high-low load signal;
wherein the water supply regulating valve group (<NUM>) comprises a first valve (<NUM>) and a second valve (<NUM>), the first valve (<NUM>) is selectively opened or closed in response to the high-low load signal, and the second valve (<NUM>) is selectively opened or closed in response to the high-low load signal.