A marine generator set grid-connected system and grid-connected operation method

Abstract

An embodiment of the present invention discloses a marine generator set grid-connected system and operating method. The system includes: at least one shaft generator, at least one steam turbine generator, at least one first and second frequency converters, and a power station management module. The shaft generator provides a preset power signal to the power grid system; the steam turbine generator provides different power signals to the power grid system under different environmental conditions. Both the shaft generator and the steam turbine generator have first and second operating modes. The first frequency converter maintains the frequency of the shaft generator according to the frequency of the power grid system; the second frequency converter maintains the frequency of the steam turbine generator according to the frequency of the power grid system. The management module identifies different environmental conditions and, when identifying the first environmental condition, determines whether the steam turbine generator is operating in the first operating mode. If the steam turbine generator is operating in the first operating mode, the second frequency converter is controlled to maintain the frequency of the steam turbine generator, and the steam turbine generator is controlled to output actual power according to the power target signal.

Description

Technical Field

[0001] The embodiments of the present invention relate to grid-connected technology, and in particular to a grid-connected system and a grid-connected operation method for a marine generator set. Background Art

[0002] Currently, shaft-driven power generation is widely used on various ship types, with most ships using grid-connected shaft-driven generators. In recent years, with the increasing demand for energy conservation and emission reduction, research into green and energy-saving technologies for ships has become a pressing need. Steam turbine generators are a form of green and energy-saving technology for ships. They utilize excess steam from the ship to convert it into electricity and then connect it to the ship's power grid. Since steam turbine generators have unstable power output, while shaft-driven generators have stable power output, connecting an unstable steam turbine generator to a stable shaft-driven generator and ensuring stable operation of each generator set after grid connection has become a major research focus. Summary of the Invention

[0003] The present invention provides a marine generator set grid-connected system and grid-connected operation method to achieve stable and reliable operation of each generator set. At the same time, the steam turbine generator can be used to recover waste heat at the lowest efficiency, thereby improving the steam thermal efficiency.

[0004] In a first aspect, an embodiment of the present invention provides a marine generator set grid-connected system, the system comprising: at least one shaft generator, at least one steam turbine generator, at least one first frequency converter, at least one second frequency converter, and a power station management module;

[0005] The shaft-driven generator is used to provide a preset power signal to the power grid system;

[0006] The steam turbine generator is used to provide different power signals to the power grid system under different environmental conditions; the shaft generator and the steam turbine generator both include a first operating mode and a second operating mode;

[0007] The first frequency converter is electrically connected to the shaft generator and is configured to maintain a constant frequency of the shaft generator according to the frequency of the power grid system;

[0008] The second frequency converter is electrically connected to the steam turbine generator and is used to maintain a constant frequency of the steam turbine generator according to the frequency of the power grid system;

[0009] The power station management module is used to identify different environmental conditions; and when the environmental condition is identified as the first environmental condition, determine whether the steam turbine generator is operating in the first operating mode; if the steam turbine generator is operating in the first operating mode, control the second inverter to keep the frequency of the steam turbine generator constant; and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output actual power according to the power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental condition; the maximum output power signal of the steam turbine generator under the first environmental condition is extremely smaller than the preset power signal.

[0010] Optionally, the power station management module is also used to determine whether the steam turbine generator is operating in the second operating mode when the environmental operating condition is identified as the second environmental operating mode; if the steam turbine generator is operating in the second operating mode, control the second inverter to keep the frequency of the steam turbine generator constant; and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output the maximum output power signal under the second environmental operating condition.

[0011] Optionally, the power station management module is further configured to control the first frequency converter to maintain a constant frequency of the shaft generator; and when the frequency of the shaft generator follows the frequency of the power grid system, control the shaft generator to output the preset power signal.

[0012] In a second aspect, an embodiment of the present invention provides a method for grid-connected operation of a marine generator set, characterized in that it is applied to the marine generator set grid-connected system described in the first aspect above, and the marine generator set grid-connected operation method includes:

[0013] Identify different environmental conditions;

[0014] When the environmental operating condition is identified as the first environmental operating condition, determining whether the steam turbine generator is operating in the first operating mode;

[0015] If the steam turbine generator operates in the first operating mode, the second inverter is controlled to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, the steam turbine generator is controlled to output actual power according to a power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental operating condition; the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely smaller than a preset power signal.

[0016] Optionally, controlling the steam turbine generator to output actual power according to the power target signal includes:

[0017] Obtaining an actual output power signal of the steam turbine generator under a current first environmental operating condition;

[0018] When the actual output power signal is less than the power target signal, controlling the steam turbine generator to output actual power according to the actual output power signal;

[0019] When the actual output power signal is greater than the power target signal, the steam turbine generator is controlled to output actual power according to the power target signal.

[0020] Optionally, also include:

[0021] When the environmental operating condition is identified as the second environmental operating condition, determining whether the steam turbine generator is operating in the second operating mode;

[0022] If the steam turbine generator operates in the second operating mode, the second frequency converter is controlled to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, the steam turbine generator is controlled to output a maximum output power signal under the second environmental operating condition.

[0023] Optionally, also include:

[0024] Control the first frequency converter to maintain the frequency of the shaft generator constant, and when the frequency of the shaft generator follows the frequency of the power grid system, control the shaft generator to output a preset power signal

[0025] In an embodiment of the present invention, the power plant management module identifies different environmental conditions; and when the environmental condition is identified as a first environmental condition, determines whether the steam turbine generator is operating in the first operating mode; if the steam turbine generator is operating in the first operating mode, controls the second frequency converter to maintain a constant frequency of the steam turbine generator; and when the frequency of the steam turbine generator follows the frequency of the power grid system, controls the steam turbine generator to output actual power according to a power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental condition; the maximum output power signal of the steam turbine generator under the first environmental condition is extremely less than a preset power signal. In this way, the steam turbine generator outputs actual power according to the power target signal under the first environmental condition, avoiding the risk of the steam turbine generator being unable to output power due to its low output power under the first environmental condition being overtaken by the larger preset power signal output by the shaft generator, or directly causing the preset power signal output by the shaft generator to decrease, thereby achieving stable grid-connected operation of the entire generator set and simultaneously utilizing the steam turbine generator's maximum efficiency to recover waste heat, thereby improving steam thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural diagram of a marine generator grid-connected system provided by an embodiment of the present invention;

[0027] Figure 2 This is a flow chart of a method for grid-connected operation of a marine generator set provided by an embodiment of the present invention;

[0028] Figure 3 The present invention provides another method for the grid-connected operation of a marine generator set. DETAILED DESCRIPTION

[0029] Figure 1 FIG. 1 is a structural diagram of a marine generator grid-connected system provided by an embodiment of the present invention; FIG. Figure 1 As shown, the system includes: at least one shaft generator 10, at least one steam turbine generator 20, at least one first frequency converter 30, at least one second frequency converter 40 and a power station management module 50; the shaft generator 10 is used to provide a preset power signal to the power grid system; the steam turbine generator 20 is used to provide different power signals to the power grid system under different environmental conditions; the shaft generator 10 and the steam turbine generator 20 both include a first operating mode and a second operating mode; the first frequency converter 30 is electrically connected to the shaft generator 10 and is used to maintain a constant frequency of the shaft generator according to the frequency of the power grid system; the second frequency converter 40 is electrically connected to the steam turbine generator 20 and is used to maintain a constant frequency of the steam turbine generator according to the frequency of the power grid system;

[0030] The power station management module 50 is used to identify different environmental operating conditions; and when the environmental operating condition is identified as the first environmental operating condition, determine whether the steam turbine generator 20 is operating in the first operating mode; if the steam turbine generator 20 is operating in the first operating mode, control the second inverter 40 to maintain the frequency of the steam turbine generator; and when the frequency of the steam turbine generator 20 follows the frequency of the power grid system, control the steam turbine generator 20 to output actual power according to the power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental operating condition; the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely smaller than the preset power signal.

[0031] The shaft generator 10 is powered by stable mechanical energy, and its output power signal is stable. The steam turbine generator 20 utilizes thermoelectric conversion, and its air intake is derived from excess steam generated by the ship. The excess steam generated by the ship serves as the turbine generator's power source. Since changes in the ship's main engine load and service steam usage affect the turbine's air intake, the power generation of the turbine generator set is significantly affected by environmental conditions, and the turbine generator outputs different power signals under different environmental conditions, resulting in an unstable output power signal. Generally, when the environmental condition is a first environmental condition, the service steam volume is large, the excess steam generated by the ship is small, the turbine's air intake is small, the turbine generator's power source is small, and its output power is small. Exemplarily, the first environmental condition is winter. When the environmental condition is a second environmental condition, the service steam volume is small, the excess steam generated by the ship is large, the turbine's air intake is large, the turbine generator's power source is large, and its output power is large. Exemplarily, the second environmental condition is summer or normal operating conditions.

[0032] The shaft generator 10 and the steam turbine generator 20 both include a first operating mode and a second operating mode; wherein the first operating mode is a constant speed control mode, and the second operating mode is a drooping speed control mode; under the first environmental operating condition, the steam turbine generator 20 operates in a constant speed control mode, which can make the steam turbine generator 20 operate at a constant frequency, so that the power station management module 50 controls the actual power output of the steam turbine generator 20; it should be noted here that under the first environmental operating condition, the output power of the steam turbine generator 20 is relatively small, while the preset power signal output by the shaft generator 10 is relatively large. The steam turbine generator 20 operates in a constant speed control mode, which avoids the risk of the smaller power output by the steam turbine generator 20 being snatched by the larger preset power signal output by the shaft generator 10, resulting in the steam turbine generator 20 being unable to output power or the power output of the steam turbine generator 20 being unstable under the first environmental operating condition, and can make the steam turbine generator 20 operate at a constant frequency, so that the power station management module 50 controls the actual power output of the steam turbine generator 20.

[0033] Furthermore, the power station management module 50 controls the second inverter 40 to maintain a constant frequency of the steam turbine generator 20. When the frequency of the steam turbine generator 20 follows the frequency of the power grid system, the power station management module 50 controls the steam turbine generator 20 to output actual power according to a power target signal. Specifically, the power target signal is the maximum output power signal of the steam turbine generator under the first environmental operating condition. When the actual output power signal of the steam turbine generator 20 under the current first environmental operating condition is less than the power target signal, the steam turbine generator 20 is controlled to output actual power according to the actual output power signal. When the actual output power signal is greater than the power target signal, the steam turbine generator 20 is controlled to output actual power according to the power target signal. This avoids the risk of the steam turbine generator 20 being unable to output power due to the large preset power signal output by the shaft generator 10 due to its low output power under the first environmental operating condition, thereby achieving stable grid-connected operation of the entire generator set. At the same time, the steam turbine generator can be used to recover waste heat at the maximum efficiency, thereby improving the thermal efficiency of steam.

[0034] Optional, such as Figure 1 As shown, the power station management module 50 is further used to determine whether the steam turbine generator 20 is operating in the second operating mode when the environmental operating condition is identified as the second environmental operating condition; if the steam turbine generator 20 is operating in the second operating mode, control the second inverter 40 to maintain the frequency of the steam turbine generator; and when the frequency of the steam turbine generator 20 follows the frequency of the power grid system, control the steam turbine generator 20 to output the maximum output power signal under the second environmental operating condition.

[0035] In the second environmental operating condition, the output power of the steam turbine generator 20 is relatively large, and there is no risk of power being snatched away by the larger preset power signal output by the shaft generator 10. The steam turbine generator 20 can operate in a droop speed control mode. Furthermore, the second frequency converter 40 is controlled to maintain a constant frequency of the steam turbine generator 20. When the frequency of the steam turbine generator 20 follows the frequency of the power grid system, ensuring that it matches the power grid system frequency, the steam turbine generator 20 is controlled to output the maximum output power signal under the second environmental operating condition, thereby achieving stable grid connection between the steam turbine generator 20 and the shaft generator 10 under the second environmental operating condition. It is understood that, under the same main engine load on the ship, the maximum output power signal output by the steam turbine generator 20 under the second environmental operating condition is greater than the maximum output power signal output by the steam turbine generator 20 under the first environmental operating condition.

[0036] Optional, such as Figure 1 As shown, the power station management module 50 is further configured to control the first frequency converter 30 to maintain the frequency of the shaft generator 10 ; and when the frequency of the shaft generator 10 follows the frequency of the power grid system, control the shaft generator 10 to output a preset power signal.

[0037] Among them, since the power output by the shaft generator 10 is stable under various environmental conditions, the shaft generator 10 can operate in the first operating mode or the second operating mode; the power station management module 50 controls the first inverter 30 to maintain a constant frequency of the shaft generator 10; and when the frequency of the shaft generator 10 follows the frequency of the power grid system, the shaft generator 10 is controlled to output a preset power signal in the first operating mode or the second operating mode, thereby realizing the grid-connected operation of the shaft generator 10 and the steam turbine generator under various environmental conditions.

[0038] The embodiment of the present invention also provides a method for grid-connected operation of a marine generator set. Figure 2 FIG. 1 is a flow chart of a method for grid-connected operation of a marine generator set provided by an embodiment of the present invention, such as Figure 2 As shown, the method includes the following steps:

[0039] S110. Identify different environmental working conditions.

[0040] This method is applied to the marine generator grid-connected system of the above-mentioned embodiment. The power plant management module can be used to identify different environmental operating conditions. These environmental operating conditions include a first environmental operating condition and a second environmental operating condition. When the first environmental operating condition is present, the ship generates less excess steam due to a large amount of service steam, the turbine intake is small, the turbine generator's power source is small, and its output power is small. When the second environmental operating condition is present, the ship generates more excess steam due to a small amount of service steam, the turbine intake is large, the turbine generator's power source is large, and its output power is large.

[0041] S120: When the environmental operating condition is identified as the first environmental operating condition, determine whether the steam turbine generator is operating in the first operating mode.

[0042] Among them, the first operating mode is the constant speed control mode; under the first environmental working condition, the output power of the steam turbine generator is relatively small, while the preset power signal output by the shaft belt generator is relatively large. The steam turbine generator operates in the constant speed control mode, which avoids the risk that the smaller power output by the steam turbine generator is snatched by the larger preset power signal output by the shaft belt generator, resulting in the steam turbine generator being unable to output power or the power output of the steam turbine generator being unstable under the first environmental working condition. The steam turbine generator can operate at a constant frequency, so that the power station management module controls the actual power output of the steam turbine generator.

[0043] S130. If the steam turbine generator operates in the first operating mode, control the second inverter to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output actual power according to the power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental operating condition; the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely smaller than the preset power signal.

[0044] Controlling the steam turbine generator to output actual power based on the power target signal includes: obtaining the actual output power signal of the steam turbine generator under the current first environmental operating condition; when the actual output power signal is less than the power target signal, controlling the steam turbine generator to output actual power at the actual output power signal; and when the actual output power signal is greater than the power target signal, controlling the steam turbine generator to output actual power at the power target signal. This avoids the risk of the steam turbine generator being unable to output power due to its low output power under the first environmental operating condition being overtaken by the larger preset power signal output by the shaft generator, thereby achieving stable grid-connected operation of the entire generator set. Furthermore, the steam turbine generator can be used to recover waste heat at its maximum efficiency, thereby improving steam thermal efficiency.

[0045] Optionally, based on the above embodiment, further optimization is performed. Figure 3 FIG. 1 is a flow chart of another method for grid-connected operation of a marine generator set provided by an embodiment of the present invention; FIG. Figure 3 As shown, the method includes the following steps:

[0046] S210: Identify different environmental working conditions.

[0047] S220: When the environmental operating condition is identified as the first environmental operating condition, determine whether the steam turbine generator is operating in the first operating mode.

[0048] S230. If the steam turbine generator operates in the first operating mode, control the second frequency converter to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output actual power according to the power target signal; wherein the power target signal is determined by the maximum output power signal of the steam turbine generator under the first environmental operating condition; the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely smaller than the preset power signal.

[0049] S240: When it is identified that the environmental operating condition is the second environmental operating condition, determine whether the steam turbine generator is operating in the second operating mode.

[0050] S250: If the steam turbine generator operates in the second operating mode, control the second frequency converter to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output a maximum output power signal under the second environmental operating condition.

[0051] Among them, the first operating mode is the droop speed control mode; under the second environmental condition, the output power of the steam turbine generator is relatively large, and there is no risk of power being snatched away by the larger preset power signal output by the shaft generator. The steam turbine generator can operate in the droop speed control mode. Furthermore, the second inverter is controlled to maintain the frequency of the steam turbine generator; and when the frequency of the steam turbine generator follows the frequency of the power grid system, to ensure that it matches the frequency of the power grid system, the steam turbine generator is controlled to output the maximum output power signal under the second environmental condition, thereby achieving stable grid connection of the steam turbine generator with the shaft generator under the second environmental condition; it can be understood here that, under the condition that the main engine load on the ship is the same, the maximum output power signal output by the steam turbine generator under the second environmental condition is greater than the maximum output power signal output by the steam turbine generator under the first environmental condition.

[0052] S260 , controlling the first frequency converter to maintain a constant frequency of the shaft generator, and when the frequency of the shaft generator follows the frequency of the power grid system, controlling the shaft generator to output a preset power signal.

[0053] Among them, since the power output by the shaft generator is stable under various environmental working conditions, the shaft generator can operate in the first operating mode or the second operating mode; the power station management module controls the first inverter to maintain a constant frequency of the shaft generator; and when the frequency of the shaft generator follows the frequency of the power grid system, the shaft generator is controlled to output a preset power signal in the first operating mode or the second operating mode, thereby realizing the grid-connected operation of the shaft generator and the steam turbine generator under various environmental working conditions.

[0054] Based on the above embodiments, this embodiment solves the problem that the steam turbine generator is unable to output power due to the risk of the shaft generator outputting a larger preset power signal to snatch power under the first environmental working condition. The power station management module 50 controls the steam turbine generator to output the maximum power signal under the second environmental working condition and controls the shaft generator to output the preset power signal, thereby achieving stable grid-connected operation of the entire generator set.

[0055] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A marine generator grid-connected system, characterized in that: include: At least one shaft generator, at least one steam turbine generator, at least one first frequency converter, at least one second frequency converter and a power plant management module; The shaft-driven generator is used to provide a preset power signal to the power grid system; The steam turbine generator is used to provide different power signals to the power grid system under different environmental conditions; the shaft generator and the steam turbine generator both include a first operating mode and a second operating mode; The first frequency converter is electrically connected to the shaft generator and is configured to maintain a constant frequency of the shaft generator according to the frequency of the power grid system; The second frequency converter is electrically connected to the steam turbine generator and is used to maintain a constant frequency of the steam turbine generator according to the frequency of the power grid system; The power station management module is used to identify different environmental conditions; When the environmental operating condition is identified as the first environmental operating condition, it is determined whether the steam turbine generator is operating in the first operating mode; if the steam turbine generator is operating in the first operating mode, the second frequency converter is controlled to maintain a constant frequency of the steam turbine generator; and when the frequency of the steam turbine generator follows the frequency of the power grid system, the steam turbine generator is controlled to output actual power according to a power target signal; wherein the power target signal is determined by a maximum output power signal of the steam turbine generator under the first environmental operating condition; and the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely less than the preset power signal; Wherein, the first environmental operating condition is an operating condition in which the air intake volume of the steam turbine generator is large and the output power of the steam turbine generator is large; The first operating mode is a constant speed control mode.

2. The marine generator grid-connected system according to claim 1, characterized in that: The power station management module is further configured to, when identifying that the environmental operating condition is the second environmental operating condition, determine whether the steam turbine generator is operating in the second operating mode; if the steam turbine generator is operating in the second operating mode, control the second frequency converter to maintain a constant frequency of the steam turbine generator; and when the frequency of the steam turbine generator follows the frequency of the power grid system, control the steam turbine generator to output a maximum output power signal under the second environmental operating condition; The second environmental operating condition is a condition in which the air intake volume of the steam turbine generator is small and the output power of the steam turbine generator is small; and the second operating mode is a droop speed control mode.

3. The marine generator grid-connected system according to claim 1, characterized in that: The power station management module is further configured to control the first frequency converter to maintain a constant frequency of the shaft generator; and when the frequency of the shaft generator follows the frequency of the power grid system, control the shaft generator to output the preset power signal.

4. A method for grid-connected operation of a marine generator set, characterized in that: Applicable to the marine generator set grid-connected system according to any one of claims 1 to 3 above, the marine generator set grid-connected operation method comprises: Identify different environmental conditions; When the environmental operating condition is identified as the first environmental operating condition, determining whether the steam turbine generator is operating in the first operating mode; If the steam turbine generator operates in the first operating mode, controlling the second frequency converter to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, controlling the steam turbine generator to output actual power according to a power target signal; wherein the power target signal is determined by a maximum output power signal of the steam turbine generator under the first environmental operating condition; and the maximum output power signal of the steam turbine generator under the first environmental operating condition is extremely less than the preset power signal; Wherein, the first environmental operating condition is an operating condition in which the air intake volume of the steam turbine generator is large and the output power of the steam turbine generator is large; The first operating mode is a constant speed control mode.

5. The method for grid-connected operation of a marine generator set according to claim 4, characterized in that: Controlling the steam turbine generator to output actual power according to the power target signal includes: Obtaining an actual output power signal of the steam turbine generator under a current first environmental operating condition; When the actual output power signal is less than the power target signal, controlling the steam turbine generator to output actual power according to the actual output power signal; When the actual output power signal is greater than the power target signal, the steam turbine generator is controlled to output actual power according to the power target signal.

6. The method for grid-connected operation of a marine generator set according to claim 5, characterized in that: Also includes: When the environmental operating condition is identified as the second environmental operating condition, determining whether the steam turbine generator is operating in the second operating mode; If the steam turbine generator operates in the second operating mode, controlling the second frequency converter to maintain a constant frequency of the steam turbine generator, and when the frequency of the steam turbine generator follows the frequency of the power grid system, controlling the steam turbine generator to output a maximum output power signal under the second environmental operating condition; The second environmental operating condition is a condition in which the air intake volume of the steam turbine generator is small and the output power of the steam turbine generator is small; and the second operating mode is a droop speed control mode.

7. The method for grid-connected operation of a marine generator set according to claim 6, characterized in that: Also includes: The first frequency converter is controlled to maintain a constant frequency of the shaft generator, and when the frequency of the shaft generator follows the frequency of the power grid system, the shaft generator is controlled to output the preset power signal.

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