Primary frequency modulation method for variable speed pumped storage unit based on fixed runner stroke

Abstract

The application discloses a kind of variable-speed pumped storage unit primary frequency modulation methods based on servomotor stroke fixing, including obtaining unit real-time operating parameter and unit parameter;Frequency deviation amount is calculated;The corresponding electromagnetic power variation amount obtained by calculation is as the control amount of the primary frequency modulation of target variable-speed pumped storage unit, and the primary frequency modulation is completed;The water turbine on the prime mover side of target variable-speed pumped storage unit is kept working at the best target opening value under current water head and current power setting value during primary frequency modulation process, and only through the change of water turbine speed and water turbine flow changes the output of prime mover side.The application realizes not only the primary frequency modulation of variable-speed pumped storage unit by innovative frequency modulation method, but also the reliability of the method of the application is high, accuracy is good and practicality is high.

Description

Technical Field

[0001] This invention belongs to the field of pumped storage power station control technology, specifically relating to a primary frequency regulation method for a variable speed pumped storage unit based on a fixed relay stroke. Background Technology

[0002] Pumped-storage hydroelectric power stations are an important component of the power system. During periods of low load, pumped-storage hydroelectric power stations can act as a load, transforming into pumping units to draw water from lower elevations and store it at higher elevations. During periods of high load, they can act as a power source, transforming into hydroelectric generating units to generate electricity from the stored water, thus providing additional available power to the power system. It is precisely because of this flexible nature that pumped-storage hydroelectric power stations have become one of the most important parts of the power system.

[0003] Currently, traditional pumped storage power stations generally use conventional hydroelectric generators or constant-speed pumped storage units. Although these units have been in use for a long time and good operating experience has been accumulated for power systems with these units, they are difficult to operate under low load conditions and exhibit a significant drop in efficiency when operating away from their design operating points. Therefore, these units are gradually becoming unsuitable for the operating requirements of today's power systems.

[0004] Variable-speed pumped storage units are an innovative technology developed in recent years. They have advantages such as a wide operating range, a large adjustable power output, and extremely high operating efficiency under steady-state conditions. Therefore, variable-speed pumped storage units will be the core units of future pumped storage power plants. However, the primary frequency regulation scheme for variable-speed pumped storage units cannot be directly applied to the primary frequency regulation schemes of existing traditional units, and currently, there is no research in my country specifically on the primary frequency regulation of variable-speed pumped storage units. Summary of the Invention

[0005] The purpose of this invention is to provide a highly reliable, accurate, and practical method for primary frequency regulation of variable speed pumped storage units based on a fixed relay stroke.

[0006] The primary frequency regulation method for a variable speed pumped storage unit based on a fixed relay stroke provided by this invention includes the following steps:

[0007] S1. Obtain the real-time operating parameters and unit parameters of the target variable-speed pumped storage unit;

[0008] S2. Calculate the frequency deviation of the target variable speed pumped storage unit based on the data obtained in step S1;

[0009] S3. Based on the frequency deviation calculated in step S2, calculate the change in electromagnetic power of the target variable speed pumped storage unit during the first frequency regulation.

[0010] S4. Use the change in electromagnetic power obtained in step S3 as the control quantity for the primary frequency regulation of the target variable speed pumped storage unit to complete the primary frequency regulation of the variable speed pumped storage unit.

[0011] S5. During the frequency regulation process of steps S2 to S4, the turbine on the prime mover side of the target variable speed pumped storage unit is kept at the optimal target opening value under the current head and current power setting value, and the output of the prime mover side is changed only by the change of turbine speed and turbine flow rate.

[0012] Step S2, which involves calculating the frequency deviation of the target variable-speed pumped storage unit based on the data obtained in step S1, specifically includes the following steps:

[0013] The frequency deviation Δf of the target variable-speed pumped storage unit is calculated using the following formula:

[0014] Δf=E f (f ref -f)

[0015] In the formula f ref f is the power grid reference frequency; f is the measured power grid frequency; E f The frequency dead zone is a manually set unit, and

[0016] Step S3, which involves calculating the electromagnetic power change of the target variable-speed pumped storage unit during primary frequency regulation based on the frequency deviation obtained in step S2, specifically includes the following steps:

[0017] The change in electromagnetic power m of the target variable-speed pumped storage unit during primary frequency regulation is calculated using the following formula. g :

[0018]

[0019] In the formula, Δf is the frequency deviation of the target variable-speed pumped storage unit obtained in step S2; e g e is the self-regulating coefficient of the generator unit in a target variable speed pumped storage unit; p The power permanent interpolation coefficient for the target variable speed pumped storage unit.

[0020] The present invention provides a primary frequency regulation method for variable speed pumped storage units based on fixed relay stroke. Through innovative frequency regulation methods, it not only realizes the primary frequency regulation of variable speed pumped storage units, but also has high reliability, high accuracy and high practicality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0022] Figure 2 This is a schematic diagram of the per-unit value curve of the rotational speed when the network frequency suddenly increases by 0.1Hz according to the present invention.

[0023] Figure 3 This is a schematic diagram of the relay travel curve for a sudden increase in network frequency of 0.1Hz according to the present invention.

[0024] Figure 4 The frequency variation of this invention is ±0.1Hz P 11 -n 11 A schematic diagram of the migration curve. Detailed Implementation

[0025] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The primary frequency regulation method for a variable speed pumped storage unit based on a fixed relay stroke provided by the present invention includes the following steps:

[0026] S1. Obtain the real-time operating parameters and unit parameters of the target variable-speed pumped storage unit;

[0027] S2. Based on the data obtained in step S1, calculate the frequency deviation of the target variable-speed pumped storage unit; specifically including the following steps:

[0028] The frequency deviation Δf of the target variable-speed pumped storage unit is calculated using the following formula:

[0029] Δf=E f (f ref -f)

[0030] In the formula f ref f is the power grid reference frequency; f is the measured power grid frequency; E f The frequency dead zone is a manually set unit, and

[0031] S3. Based on the frequency deviation calculated in step S2, calculate the change in electromagnetic power of the target variable-speed pumped storage unit during the first frequency regulation; specifically including the following steps:

[0032] The change in electromagnetic power m of the target variable-speed pumped storage unit during primary frequency regulation is calculated using the following formula. g :

[0033]

[0034] In the formula, Δf is the frequency deviation of the target variable-speed pumped storage unit obtained in step S2; e g e is the self-regulating coefficient of the generator unit in a target variable speed pumped storage unit; p The power perpetual interpolation coefficient for the target variable speed pumped storage unit;

[0035] S4. Use the change in electromagnetic power obtained in step S3 as the control quantity for the primary frequency regulation of the target variable speed pumped storage unit to complete the primary frequency regulation of the variable speed pumped storage unit.

[0036] In practical implementation, the obtained electromagnetic power change m g and the prime mover torque of the water turbine m t After being superimposed, the data is input to the electric generator in the target variable speed pumped storage unit to control the electric generator, which in turn controls the speed of the turbine; at the same time, the flow rate of the turbine itself is controlled by the water intake system.

[0037] S5. During the frequency regulation process in steps S2 to S4, the turbine on the prime mover side of the target variable speed pumped storage unit is kept at the optimal target opening value under the current head and power setting. The turbine guide vane servo stroke or the turbine guide vanes remain unchanged. The output of the prime mover side is changed only by the change in turbine speed and turbine flow rate, i.e., the turbine's prime mover torque m. t The changes are caused only by variations in rotational speed and flow rate; the turbine's operating point always slides along a constant opening line.

[0038] Traditional hydroelectric generators achieve primary frequency regulation at the turbine governor side. This invention innovatively proposes implementing primary frequency regulation at the converter side, adjusting the electromagnetic power output based on changes in the grid frequency. The primary frequency regulation function of this invention features rapid response; during the primary frequency regulation operation, the turbine slides along its constant opening line, achieving a primary frequency regulation response within milliseconds. Because the primary frequency fluctuation amplitude is limited, it maintains the turbine operating near its high-efficiency range. This method is particularly suitable for situations with frequent primary frequency regulation operations and strict friction requirements in the servo control loop. However, this method is only applicable to low specific speed mixed-flow turbines.

[0039] Figure 2 This is a schematic diagram of the per-unit value curve of the rotational speed when the network frequency suddenly increases by 0.1Hz according to the present invention. Figure 3 This is a schematic diagram of the relay travel curve for a sudden increase in network frequency of 0.1Hz according to the present invention. Figure 4Method 3 describes the migration trajectory of unit power P11 - unit speed n11 during the primary frequency regulation dynamic adjustment process of the method of the present invention. Method 2 describes the migration trajectory of unit power P11 - unit speed n11 during the primary frequency regulation dynamic adjustment process of the variable speed pumped storage unit control method based on dynamic target values. Method 1 describes the migration trajectory of unit power P11 - unit speed n11 during the primary frequency regulation dynamic adjustment process of the variable speed unit based on power setpoint correction. Figures 2-4 It can be seen that the method of the present invention has a good control effect.

[0040] The frequency regulation method provided by this invention offers rapid electromagnetic power response, completing electromagnetic power adjustment within milliseconds. Furthermore, during the adjustment process, the deviation of the grid frequency from the rated frequency is generally small. Therefore, the turbine operates in a high-efficiency range at both the initial and final stages of the frequency regulation, resulting in high turbine operating efficiency. Moreover, this invention uses speed regulation to adjust turbine output and flow rate during the primary frequency regulation response, offering the advantage of rapid turbine output adjustment on the prime mover side. Simultaneously, only the guide vane servo travel remains constant during the primary frequency regulation, reducing wear on mechanical components such as the servo and control loop, and extending the unit's lifespan. Finally, the use of speed regulation to adjust turbine output and flow rate during the primary frequency regulation response provides advantages such as low water hammer in the turbine's water intake system and good unit stability during adjustment.

Claims

1. A method for primary frequency regulation of a variable speed pumped storage unit based on a fixed relay stroke, comprising the following steps: S1. Obtain the real-time operating parameters and unit parameters of the target variable-speed pumped storage unit; S2. Based on the data obtained in step S1, calculate the frequency deviation of the target variable-speed pumped storage unit; specifically including the following steps: The frequency deviation of the target variable-speed pumped storage unit is calculated using the following formula. : In the formula This is the power grid reference frequency; This is the measured frequency of the power grid. The frequency dead zone is a manually set unit, and ; S3. Based on the frequency deviation calculated in step S2, calculate the change in electromagnetic power of the target variable-speed pumped storage unit during the first frequency regulation; specifically including the following steps: The electromagnetic power change of the target variable-speed pumped storage unit during primary frequency regulation is calculated using the following formula. : In the formula The frequency deviation of the target variable-speed pumped storage unit obtained in step S2; The self-regulation coefficient of the generator unit in the target variable speed pumped storage unit; The power permanent interpolation coefficient for the target variable speed pumped storage unit; S4. Use the change in electromagnetic power obtained in step S3 as the control quantity for the primary frequency regulation of the target variable speed pumped storage unit to complete the primary frequency regulation of the variable speed pumped storage unit. S5. During the frequency regulation process of steps S2 to S4, the turbine on the prime mover side of the target variable speed pumped storage unit is kept at the optimal target opening value under the current head and current power setting value, and the output of the prime mover side is changed only by the change of turbine speed and turbine flow rate.

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