System and method for improving primary frequency regulation performance of a combined cycle generator set

Abstract

The application discloses a system and method for improving primary frequency modulation performance of a combined cycle generator unit, and the system and method improve the control system of the combined cycle unit, increase the control of the opening degree of the adjusting valve by the steam turbine speed signal, make the steam turbine change the opening degree of the valve when the external load and frequency change, participate in frequency regulation, improve the load response capability and frequency modulation capability of the steam turbine, cope with the change of the power grid load and frequency, improve the frequency modulation performance of the thermal power generator unit under the condition of large-scale renewable energy access, and improve the access rate of renewable energy.

Description

Technical Field

[0001] This invention belongs to the field of thermal power unit control technology, specifically relating to a system and method for improving the primary frequency regulation performance of combined cycle generator units. Background Technology

[0002] Gas-steam combined cycle generator sets offer advantages such as high efficiency and low energy consumption, rapid start-up, flexible regulation, short construction period, and low environmental pollution, making them a recognized approach to addressing environmental degradation. With the gradual increase in grid capacity and the large-scale development of new energy units such as photovoltaic and wind power, the stability of grid frequency and load has been challenged. To ensure frequency stability during grid load changes and guarantee a high-quality power supply, the characteristics of gas-steam combined cycle generator sets allow for rapid grid primary frequency regulation, thereby enhancing the overall stability of the grid.

[0003] The gas-steam combined cycle generator consists of two parts: a gas turbine cycle and a steam power cycle. In the gas turbine cycle, atmospheric gas is compressed by a compressor and then burned in the combustion chamber to generate high-temperature gas. This gas expands in the turbine, doing work to drive the generator. The steam power cycle utilizes the exhaust gas from the gas turbine to exchange heat with feedwater in a waste heat boiler, generating superheated steam. This superheated steam expands in a steam turbine, doing work to drive the generator, and the exhaust steam returns to the waste heat boiler via a condenser. The steam power cycle utilizes the waste heat from the gas turbine cycle exhaust to increase the efficiency of the power cycle.

[0004] The existing primary frequency regulation control method for gas-steam combined cycle generator units mainly relies on the gas turbine for primary frequency regulation, with the gas turbine primarily controlling fuel flow. When the unit is subjected to grid load disturbances, a difference arises between the unit's load and the actual load signal, causing a change in the unit's speed. The gas turbine's control system then adjusts the fuel control signal based on this speed change, altering the opening of the fuel regulating valve and thus the fuel flow rate. Ultimately, this results in a rapid change in the gas turbine's output power to cope with the grid load disturbance. The steam turbine employs front-pressure regulation, controlling the opening of its regulating valve based on the boiler outlet pressure. Waste heat from the gas turbine exhaust causes a change in the steam pressure generated in the waste heat boiler. This pressure change signal is used to adjust the regulating valve opening, following the gas turbine's load, thus performing load-following action. However, this method does not actively participate in the unit's primary frequency regulation. With only the gas turbine participating in the unit's primary frequency regulation, the unit's primary frequency regulation capability under grid load disturbances is limited. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for improving the primary frequency regulation performance of combined cycle generator sets. This system and method can rapidly adjust the unit power under grid load disturbances, utilize the boiler's heat storage to participate in the primary frequency regulation of the grid, solve the problem that the steam turbine part of conventional combined cycle generator sets does not participate in primary frequency regulation, improve the primary frequency regulation performance of combined cycle generator sets, and enhance the primary frequency regulation capability of combined cycle generator sets.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for improving the primary frequency regulation performance of a combined cycle generator set, which selects the control mode based on the unit's operating status.

[0008] When the unit is running stably, the pressure difference is obtained by calculating the difference between the main steam pressure signal and the pressure setpoint signal. After the pressure difference passes through the pressure deviation dead zone, once the pressure difference exceeds the dead zone amplitude, it passes through the pressure loop PID controller, and then through the valve opening speed limiting and amplitude limiting stages to obtain the steam turbine regulating valve opening control signal P. CV Based on the principle of fully utilizing the waste heat of the gas turbine, the steam turbine controls the opening of the steam turbine regulating valve according to the outlet pressure of the waste heat boiler.

[0009] The steam turbine speed corresponds one-to-one with the frequency. When the grid frequency changes, the steam turbine speed signal participates in the regulation of the combined cycle generator unit. Based on the deviation signal between the steam turbine's given speed and the unit's actual speed, after passing through a speed dead zone stage, and after the speed deviation exceeds the dead zone amplitude, the control signal P for the steam turbine regulating valve opening is obtained through a speed inequality rate inverse stage, followed by valve opening speed limiting and amplitude limiting stages. CV It controls the opening of the steam turbine regulating valve, utilizes boiler heat storage, participates in the primary frequency regulation of the power grid, and improves the frequency regulation performance of the combined cycle unit.

[0010] A further improvement of the present invention is that:

[0011] Preferably, when the unit is running stably, when the exhaust heat of the gas turbine increases, the heat absorbed by the waste heat boiler increases, the evaporation of water steam increases, and the outlet pressure of the waste heat boiler increases. The pressure transmitter measures the change in the outlet pressure of the waste heat boiler, compares it with the given pressure, and uses the difference signal to control the opening of the steam turbine regulating valve, thereby changing the power of the steam turbine to utilize the waste heat from the exhaust of the gas turbine.

[0012] Preferably, when the power grid frequency changes, the steam turbine speed signal participates in the regulation, and when the power grid frequency changes, the opening of the steam turbine valve is controlled according to the deviation between the given speed and the actual speed of the steam turbine. The power of the steam turbine is changed before the steam pressure at the outlet of the waste heat boiler changes, so that the steam turbine participates in the primary frequency regulation of the power grid and improves the primary frequency regulation performance of the power grid.

[0013] Preferably, when the power grid frequency changes, the steam turbine inlet flow rate changes, which alters the power of the steam turbine. The steam turbine power, through the rotor, changes the speed of the steam turbine. The speed of the steam turbine is directly consistent with the frequency of the power grid, thereby achieving the adjustment of the power grid frequency and utilizing the heat storage of the waste heat boiler to participate in the primary frequency regulation of the power grid.

[0014] Preferably, when the grid frequency changes, a signal is output according to the unit's operating status, either in the form of main steam pressure control or speed control. After being processed by the steam turbine regulating valve opening speed limiting and amplitude limiting links, a valve opening control signal is output to change the opening of the steam turbine regulating valve and thus control the steam turbine power.

[0015] Preferably, the main steam pressure control method is to output a control signal based on the pressure difference signal, and the speed control method is to output a control signal based on the speed deviation signal.

[0016] Preferably, the difference between the steam turbine regulating valve opening command and the valve stroke feedback signal is processed by the valve electro-hydraulic conversion PI controller. The output signal of the valve electro-hydraulic conversion PI controller is then passed through the oil motor integral limiting circuit to obtain the steam turbine regulating valve opening signal, and the steam turbine regulating valve opening is output to the valve stroke feedback circuit.

[0017] A system for improving the primary frequency regulation performance of a combined cycle generator set includes:

[0018] The steam power module is used to acquire the exhaust heat of the gas turbine, and obtain the main steam pressure signal by combining the exhaust heat of the gas turbine and the thermal inertia of the waste heat boiler. The thermal inertia of the waste heat boiler includes the thermal inertia of the water-cooled wall, the steam drum, and the superheater. It also obtains the steam turbine inlet valve opening signal through the main steam pressure signal; the steam turbine inlet steam flow signal through the valve opening signal; and the steam turbine power signal through the steam turbine inlet steam flow signal.

[0019] The steam turbine valve opening control module is used to change the steam flow rate into the steam turbine by changing the steam turbine valve opening, thereby changing the steam turbine power.

[0020] The actuator is used to execute the control signal for the opening degree of the steam turbine regulating valve.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention discloses a system and method for improving the primary frequency regulation performance of a combined cycle generator unit. By improving the control system of the combined cycle unit and increasing the control of the steam turbine valve opening via the speed signal, the steam turbine can adjust the valve opening to participate in power regulation when external load and frequency change, thus improving the steam turbine's load response capability to cope with grid load and frequency changes. This improves the frequency regulation performance of thermal power units under large-scale renewable energy integration conditions and increases the renewable energy integration rate. After the unit speed changes, steam is generated using the heat from the gas turbine exhaust and the heat storage of the waste heat boiler, which can meet the requirements of the grid's primary frequency regulation performance. During normal operation, the steam turbine inlet steam flow signal is adjusted via the main steam pressure signal; the opening of the steam turbine regulating valve is changed via the steam turbine inlet steam flow signal to maintain a constant waste heat boiler outlet pressure. The change in the regulating valve opening causes a change in steam turbine power. Under secondary frequency regulation, the primary frequency regulation effect is eliminated, and the steam turbine valve opening returns to its original position. Only the thermal inertia of the waste heat boiler is used for regulation during the primary frequency regulation process, and its adjustment time conforms to the primary frequency regulation response time specified by the grid, without affecting the normal operation of the steam turbine. The gas-steam combined cycle generator set with added frequency regulation function proposed in this invention can fully utilize the primary frequency regulation capability of the gas-steam combined cycle generator set, enabling the unit to quickly complete frequency regulation when the grid load is disturbed, thereby meeting the grid stability requirements.

[0023] Furthermore, when the steam turbine speed signal participates in regulation, if normal pressure regulation is applied, the greater the inertia of the waste heat boiler, the slower the rate of change of the waste heat boiler outlet pressure, and the slower the rate of change of the steam turbine power, thus limiting the steam turbine's role in grid frequency recovery. When the grid frequency changes, the opening of the steam turbine valves is controlled based on the deviation between the given and actual steam turbine speeds. The steam turbine power is changed even before the waste heat boiler outlet steam pressure changes, enabling the steam turbine to participate in the primary frequency regulation of the grid and significantly improving the primary frequency regulation performance of the grid.

[0024] In this invention, the gas turbine and steam power cycle components can adjust the opening of the fuel valve and the steam turbine regulating valve through their respective control systems in response to grid load disturbances, thereby changing the power of the gas turbine and steam turbine. The heat storage of the waste heat boiler is utilized to participate in the primary frequency regulation of the power grid, achieving rapid and efficient power and frequency regulation while meeting grid requirements. Attached Figure Description

[0025] Figure 1 This is a block diagram of the gas-steam combined cycle unit model of the present invention.

[0026] Where, n—unit speed signal; k NL —No-load fuel constant; TVP —Fuel valve time constant; T F —Fuel system time constant; T W —Air control factor; K RS —Radiation shield scaling factor; T RS —Radiator time constant; T TC —Coupling heat transfer time constant; K P —Proportional coefficient of temperature controller; T T —Temperature controller time constant; W—Gas turbine airflow; W F —Gas turbine fuel flow rate; T i —Ambient temperature; T e —Turbine exhaust temperature; Q GT —Gas turbine thermal power; Q E —Gas turbine exhaust heat; T CD —Air volume time constant; P GT —Gas turbine output power; T I —Time constant of rotor inertia; K I — Frequency regulation effect coefficient; Y— Speed ​​controller time constant; R— Power speed deviation coefficient.

[0027] Figure 2 This is a block diagram of the steam power module model of the present invention.

[0028] Where ε is the ratio of main steam pressure to steam drum pressure; T WW —Water-cooled wall time constant; T B —Superheater time constant; K B —Superheater proportionality coefficient; p T —Main steam pressure signal; P GV —Steam turbine regulating valve opening signal; g s —Steam turbine inlet steam flow signal; K D —Steam drum proportional coefficient; T H —High-pressure volumetric time constant; K H —Power proportional coefficient of high-pressure cylinder; T L —Low-pressure volumetric time constant; K L —Low-pressure cylinder power proportional coefficient; P ST —Steam turbine output power; T a — Rotor fly-up time constant; B— Rotor self-balancing coefficient; n— Unit speed signal.

[0029] Figure 3 This is a block diagram of the steam control system model of the present invention.

[0030] Where, p T —Main steam pressure signal; p ref—Pressure setpoint signal; DB—Pressure deviation dead zone; PID—Pressure loop PID controller; n—Unit speed signal; n ref —Speed ​​command signal; DB1—Die-time of primary frequency regulation of the unit; δ—Speed ​​inequality rate; V max —Control valve operating speed limit; P max —Upper limit of control valve opening command; P min —Lower limit of control valve opening command; P CV —Steam turbine regulating valve opening command.

[0031] Figure 4 This is a block diagram of the steam turbine actuator model of the present invention;

[0032] Among them, PI V —Valve electro-hydraulic conversion PI controller; T O —Oil actuator opening time constant; T C —Hydraulic actuator shut-off time constant; T LVDT —Valve stroke feedback time constant.

[0033] Figure 5 The present invention improves the steam turbine output power response curve under afterload disturbance. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] See Figure 1This invention discloses a model and control method for improving the primary frequency regulation performance of a gas-steam combined cycle generator set. The steam power module of the combined cycle includes a waste heat boiler, a steam turbine, and a control system model. The gas turbine remains unchanged and is not within the scope of this invention. In response to changes in external load and frequency, the gas turbine control system adjusts the fuel supply to the gas turbine, regulating its power output. The exhaust heat signal from the gas turbine is then input to the steam power module. The main part of this invention lies in the internal steam power cycle, which includes models of the waste heat boiler and steam turbine components, as well as the steam turbine control system and actuators.

[0037] A model and control method for improving the primary frequency regulation performance of a gas-steam combined cycle generator set, by increasing... Figure 3 and Figure 4 The steam turbine valve opening control and actuator shown are as follows: Figure 2 The steam power module model utilizes the heat storage in the waste heat boiler's water-cooled walls, steam drum, and superheater. When grid load disturbances cause a decrease in grid frequency, the steam turbine speed control system quickly activates, increasing the opening of the steam turbine regulating valve, reducing steam pressure, increasing output steam flow, and increasing the steam turbine power variation. Conversely, when grid load reduction disturbances cause an increase in grid frequency, the steam turbine speed control system quickly deactivates, reducing the steam turbine regulating valve opening, increasing the waste heat boiler outlet pressure, reducing evaporation, and decreasing the steam turbine power variation. The heat storage in the waste heat boiler participates in the primary frequency regulation of the power grid.

[0038] It should be noted that the steam turbine speed and frequency correspond one-to-one. Specifically, Where n: rotational speed; f: frequency.

[0039] The present invention provides a system and method for improving the primary frequency regulation performance of a combined cycle generator set, comprising a steam power module, a steam turbine speed control module, and a steam actuator.

[0040] See Figure 2 The steam power module includes models of a waste heat boiler, a steam turbine, and its control system. In the waste heat boiler, the exhaust heat signal Q from the gas turbine... E The main steam pressure signal p is obtained by subtracting the feedback signal from the water-cooled wall stage and the steam drum stage, and then passing it through the superheater stage. T The main steam pressure signal and the steam turbine regulating valve opening signal P GV The product yields the steam turbine inlet steam flow signal g. s The pressures are output to the steam drum and the steam turbine, respectively. ε is the ratio of the main steam pressure to the steam drum pressure, and T is the output. WW T is the time constant of the water-cooled wall; B K is the superheater time constant. B p is the superheater proportionality coefficient.T Main steam pressure signal; P GV For the steam turbine regulating valve opening signal; g s This is the steam turbine inlet steam flow signal; K D This is the steam drum proportional coefficient.

[0041] The steam turbine employs a high-pressure cylinder and a low-pressure cylinder arrangement. The steam turbine inlet flow signal is output through the high-pressure volumetric circuit to both the low-pressure volumetric circuit and the high-pressure cylinder power proportional coefficient circuit. The high-pressure cylinder output power is obtained after passing through the high-pressure cylinder power proportional coefficient circuit. The low-pressure cylinder output power is obtained through the low-pressure cylinder power proportional coefficient circuit. The sum of the high-pressure and low-pressure cylinder output powers yields the steam turbine output power P. ST It obtains the unit speed signal n through the rotor element. Where T H K is the high-pressure volumetric time constant; H T is the power proportional coefficient for the high-pressure cylinder; L K is the low-pressure volumetric time constant. L T is the low-pressure cylinder power proportional coefficient; a is the rotor lift time constant; B is the rotor self-balancing coefficient.

[0042] See Figure 3 The steam turbine speed control system changes the steam turbine's inlet steam flow by altering the opening of the steam turbine regulating valve, thereby controlling the steam turbine's speed and power to meet the primary frequency regulation requirements of the power grid. The steam turbine control system employs main steam pressure control and speed control. Main steam pressure control is used during stable unit operation, while speed control is used when subjected to power grid frequency disturbances. The control mode is selected via a branch selector. In main steam pressure control, the difference between the main steam pressure signal and the pressure setpoint signal is calculated, and the control signal is output to the branch selector through a pressure deviation dead zone and a pressure loop PID controller. In speed control, the difference between the speed setpoint signal and the unit speed signal is calculated, and the control signal is output to the branch selector through a unit primary frequency regulation speed dead zone and speed inequality rate reciprocal loop. Subsequently, the control signal outputs the steam turbine regulating valve opening control signal to the steam turbine actuator through a regulating valve speed limiting loop and a regulating valve amplitude limiting loop. Where p... T Main steam pressure signal; p ref For pressure input signal; DB is pressure deviation dead zone; PID is pressure loop PID controller; n is unit speed signal; n ref DB1 is the speed command signal; DB1 is the dead zone of the unit's primary frequency regulation speed; δ is the speed regulation inequality; (K = 1 / δ) is the reciprocal of the speed regulation inequality, i.e., the proportional controller of the steam turbine speed control loop; V max To limit the operating speed of the control valve; P max P is the upper limit of the control signal for regulating valve opening.min The lower limit of the control signal for regulating valve opening; P CV This is the control signal for the opening of the steam turbine regulating valve.

[0043] The steam turbine actuator is a device that receives the control signal for the steam turbine regulating valve opening and changes the valve opening. In the actuator, the difference between the regulating valve opening control signal and the valve stroke feedback signal is passed to a valve electro-hydraulic PI controller. Since the hydraulic actuator has different characteristics for opening and closing, the appropriate circuit is selected based on requirements. The signal is then integrated and limited by the hydraulic actuator to obtain the steam turbine regulating valve opening signal, which is output to the valve stroke feedback circuit and the steam turbine model, respectively. The PI controller... V For valve electro-hydraulic conversion PI controller; T O T is the hydrator start-up time constant; C T is the shut-off time constant of the hydraulic actuator. LVDT This is the valve stroke feedback time constant.

[0044] When the grid load increases and the frequency decreases, the speed control system increases the opening of the regulating valve. At this time, utilizing the thermal inertia of the waste heat boiler, the main steam pressure decreases, the corresponding saturation temperature decreases, and the evaporation rate increases, resulting in an increase in the steam turbine power variation. Conversely, when the grid load decreases and the frequency increases, the speed control system decreases the opening of the regulating valve. At this time, the boiler outlet pressure and the corresponding saturation temperature increase, the boiler evaporation rate decreases, and the steam turbine power variation decreases. By utilizing the boiler's inertia to participate in grid power regulation and primary frequency control, the system helps maintain grid frequency stability.

[0045] This invention provides a system and method for improving the primary frequency regulation performance of combined cycle generator sets, which can provide a theoretical basis for the design of control systems for gas-steam combined cycle generator sets, provide technical support for improving the primary frequency regulation performance of the units, and maintain the stability of the power grid under load disturbances.

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] Example:

[0048] A gas-steam combined cycle generator unit is configured with one gas turbine, one steam turbine, one waste heat boiler, and two generators, arranged in a dual-shaft configuration. It utilizes natural circulation without supplementary combustion in the waste heat boiler. The steam turbine is a twin-cylinder unit, receiving both high-pressure and low-pressure steam streams to perform work. The rated power is 183.4 MW, the rated speed is 3000 r / min, the compressor pressure ratio is 12.3, the gas turbine airflow is 402.8 kg / s, the ambient temperature is 298 K, and the turbine exhaust temperature is 811 K. The unit operates at 80% load and is subjected to grid load disturbances of 5% and 10%, respectively. The primary frequency regulation dynamic characteristics of the unit are compared under two operating modes: operating mode 1 (steam turbine not participating in regulation) and operating mode 2 (steam turbine participating in regulation) under different grid load disturbances.

[0049] The per-unit value was calculated based on the rated output power of the steam turbine, starting from 0.8536. After 20 seconds, in operating mode 1, the steam turbine output power under the two perturbations was 0.8578 and 0.8618, respectively; in operating mode 2, the steam turbine output power under the two perturbations was 0.8759 and 0.8979, respectively.

[0050] When the unit is disturbed by increased grid load and decreased grid frequency, the steam turbine speed control system controls the regulating valve to change the valve opening, participating in primary frequency regulation. This reduces the main steam pressure, correspondingly lowers the saturation temperature, and increases evaporation, resulting in increased steam turbine power variation and completing the load regulation action. With the steam turbine engaging speed regulation and participating in the primary frequency regulation of the combined cycle unit, the steam turbine output power stabilizes within 15 seconds. Based on the theoretical power variation of the steam turbine, this represents an improvement of approximately 42% compared to operating mode 1, significantly improving the unit's frequency regulation capability.

[0051] The per-unit per unit was set based on the rated output power of the combined cycle unit, starting with a disturbance of 0.80. After 10 seconds, in operating mode 1, the combined cycle unit output power under the two disturbances was 0.8330 and 0.8665, respectively; in operating mode 2, the combined cycle unit output power under the two disturbances was 0.8406 and 0.8819, respectively. Under operating mode 2, based on the theoretical power change of the combined cycle unit, the power output was increased by approximately 19% compared to operating mode 1, increasing the unit's load response amplitude. Under secondary frequency regulation, the primary frequency regulation effect is eliminated, and the valve opening returns to its original position. There is no throttling loss during normal operation; only the thermal inertia of the waste heat boiler participates in the regulation during the primary frequency regulation process. Its adjustment time is within 60 seconds, which meets the primary frequency regulation response time stipulated by the power grid and will not affect the normal operation of the steam turbine. Figure 5 As shown.

[0052] In summary, the model and control method for improving the primary frequency regulation performance of a gas-steam combined cycle generator set of the present invention can enhance the primary frequency regulation capability of the unit, and can quickly adjust the load response of the unit under grid load disturbances, meet the grid's requirements for the primary frequency regulation adjustment time of the generator set, and maintain the stability of the grid's frequency and power.

[0053] It should be noted that steam turbine speed control is the basic control method. However, the steam turbines used in combined cycle power plants use main steam pressure regulation instead of speed regulation. This is not conducive to the combined cycle unit's participation in the primary frequency regulation of the power grid. The purpose of this invention is to use the heat storage of the waste heat boiler to improve the characteristics of the combined cycle unit's participation in the primary frequency regulation of the power grid.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the primary frequency regulation performance of a combined cycle generator set, characterized in that, The control mode is selected based on the unit's operating status. The control mode includes main steam pressure control and speed control. Main steam pressure control is used when the unit is running stably, and speed control is used when the grid frequency changes. The control mode is selected through a branch selector. When the unit is running stably, the pressure difference is obtained by calculating the difference between the main steam pressure signal and the pressure setpoint signal. After the pressure difference passes through the pressure deviation dead zone, once the pressure difference exceeds the dead zone amplitude, it passes through the pressure loop PID controller, and then through the valve opening speed limiting and amplitude limiting stages to obtain the steam turbine regulating valve opening control signal. P CV Based on the principle of fully utilizing the waste heat of the gas turbine, the steam turbine controls the opening of the steam turbine regulating valve according to the outlet pressure of the waste heat boiler. The steam turbine speed corresponds one-to-one with the frequency. When the grid frequency changes, the steam turbine speed signal participates in the regulation of the combined cycle generator unit. Based on the deviation signal between the steam turbine's given speed and the unit's actual speed, after passing through a speed dead zone stage, and after the speed deviation exceeds the dead zone amplitude, the control signal for the steam turbine regulating valve opening is obtained through a speed inequality rate inverse stage, followed by valve opening speed limiting and amplitude limiting stages. P CV By controlling the opening of the steam turbine regulating valve, the power of the steam turbine is changed before the steam pressure at the outlet of the waste heat boiler changes. The boiler heat storage is utilized to participate in the primary frequency regulation of the power grid and improve the frequency regulation performance of the combined cycle unit. When the power grid frequency changes, the steam turbine speed signal participates in the regulation. When the power grid frequency changes, the opening of the steam turbine valve is controlled according to the deviation between the given speed and the actual speed of the steam turbine. When the steam pressure at the outlet of the waste heat boiler does not change, the power of the steam turbine is changed to improve the performance of the steam turbine in participating in the primary frequency regulation of the power grid. When the power grid frequency changes, the steam turbine inlet flow rate changes, altering the steam turbine's power. This power, in turn, changes the steam turbine's speed through the rotor. The steam turbine's speed is directly aligned with the power grid frequency, thus achieving power grid frequency adjustment. The waste heat boiler's heat storage is then used to participate in the primary frequency regulation of the power grid.

2. The method for improving the primary frequency regulation performance of a combined cycle generator set according to claim 1, characterized in that, When the unit is running stably, as the heat from the gas turbine exhaust increases, the heat absorbed by the waste heat boiler increases, and the evaporation of steam increases, which in turn increases the outlet pressure of the waste heat boiler. The pressure transmitter measures the change in the outlet pressure of the waste heat boiler and compares it with the given pressure. The difference signal between the two is used to control the opening of the steam turbine regulating valve, thereby changing the power of the steam turbine to utilize the waste heat from the gas turbine exhaust.

3. The method for improving the primary frequency regulation performance of a combined cycle generator set according to claim 1, characterized in that, When the grid frequency changes, the main steam pressure control or speed control signal is output according to the unit's operating status. After being processed by the steam turbine regulating valve opening speed limiting and amplitude limiting links, the valve opening control signal is output to change the opening of the steam turbine regulating valve and realize the control of the steam turbine power.

4. The method for improving the primary frequency regulation performance of a combined cycle generator set according to claim 3, characterized in that, The main steam pressure control method outputs a control signal based on the pressure difference signal, and the speed control method outputs a control signal based on the speed deviation signal.

5. The method for improving the primary frequency regulation performance of a combined cycle generator set according to claim 1, characterized in that, The difference between the steam turbine control valve opening command and the valve stroke feedback signal is processed by the valve electro-hydraulic conversion PI controller. The output signal of the valve electro-hydraulic conversion PI controller is then passed through the oil motor integral limiting circuit to obtain the steam turbine control valve opening signal, which is then output to the valve stroke feedback circuit.

6. A system for achieving the improved primary frequency regulation performance of a combined cycle generator set according to claim 1, characterized in that, include: The steam power module is used to acquire the exhaust heat of the gas turbine, and obtain the main steam pressure signal by combining the exhaust heat of the gas turbine and the thermal inertia of the waste heat boiler. The thermal inertia of the waste heat boiler includes the thermal inertia of the water-cooled wall, the steam drum, and the superheater. It also obtains the steam turbine inlet valve opening signal through the main steam pressure signal; the steam turbine inlet steam flow signal through the valve opening signal; and the steam turbine power signal through the steam turbine inlet steam flow signal. The steam turbine valve opening control module is used to change the steam flow rate into the steam turbine by changing the steam turbine valve opening, thereby changing the steam turbine power. The actuator is used to execute the control signal for the opening degree of the steam turbine regulating valve.

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