CN117613936A - Primary frequency modulation quick response method based on variable-speed pumped storage unit - Google Patents
Primary frequency modulation quick response method based on variable-speed pumped storage unit Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J15/00—Systems for storing electric energy
- H02J15/003—Systems for storing electric energy in the form of hydraulic energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J15/00—Systems for storing electric energy
- H02J15/007—Systems for storing electric energy involving storage in the form of mechanical energy, e.g. fly-wheels
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/16—Mechanical energy storage, e.g. flywheels or pressurised fluids
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Abstract
The application discloses a quick response method of primary frequency modulation based on variable-speed pumped storage unit, which comprises the following functions: acquiring real-time running parameters and unit parameters of the unit; calculating a frequency deviation amount; when the frequency change is smaller than or equal to a set value, an active power deviation signal is output through PI control, and primary frequency modulation is completed by using the power given by the active control of the frequency converter; when the frequency deviation is larger than a set value, an active power deviation signal is output through PI control, the opening degree of the guide vane is adjusted to enable the frequency deviation to be smaller than or equal to the set value, then active output frequency modulation is quickly adjusted through the frequency converter, oscillation is avoided, and a quick primary frequency modulation effect is achieved. The method is applicable to automatic balancing of rapid load random fluctuation with smaller amplitude in the power grid, and meanwhile, frequency change caused by abnormal load mutation is buffered to a certain extent, so that safe and stable operation of the power grid is ensured.
Description
Technical Field
The invention belongs to the technical field of electric power automation, and relates to a primary frequency modulation quick response method based on a variable-speed pumped storage unit.
Background
Pumped storage power stations are an important component of electrical power systems. In the load valley period of the power system, the pumped storage power station can serve as the load of the power system, is converted into a water pump group, and pumps low water energy back to the high place for storage; in the peak load period of the power system, the pumped storage power station can serve as a power supply of the power system, and is converted into a hydroelectric generating set, so that water stored at high positions can be used for generating electricity through the hydroelectric generating set, and additional available electric energy is provided for the power system. It is because of this flexible nature of pumped-hydro power plants that pumped-hydro power plants become one of the most important parts of the power system.
Currently, a constant-speed pumped storage unit is generally adopted in a traditional pumped storage power station. For a conventional pumped storage unit, because the rotation speed is constant, the primary frequency modulation capability is poor, and the optimal unit rotation speed is usually designed under the weighted average water head, but when the water head is changed, the unit rotation speed of a water pump turbine is changed, and when the water pump turbine deviates from the optimal unit rotation speed to operate, the unit efficiency is reduced, and the unit operation is not facilitated. And the output active regulation of the conventional pumped storage unit can only be completed by regulating the mechanical input power through a speed regulator, and the flow rate flowing through the water turbine is changed to control the frequency within a target range, so that the regulation time is long, and the reaction speed is low.
In the unit adjustment process, the main parameter affecting the power adjustment is the water flow inertia time constant. Because of the inertia effect of water flow, the pressure of water hammer is increased in the pressure pipeline, the output of the water turbine is possibly increased, the effect opposite to the control effect is generated, the frequency modulation performance of the unit is deteriorated, and the influence on the frequency stability of the system is great.
The variable-speed pumped storage unit is an innovative technology in recent years, and has the advantages of wide operating range, large unit power adjustable range and extremely high operating efficiency under the steady-state operating condition of the unit; thus, a variable speed pumped-storage unit would be the core unit of a future pumped-storage power station. However, the primary frequency modulation scheme of the variable speed pumped storage unit cannot be directly applied to the primary frequency modulation scheme of the traditional unit.
The prior art discloses a variable-speed pumped storage unit primary frequency modulation method (CN 115864441A) based on servomotor stroke fixation, which comprises the steps of obtaining real-time operation parameters and unit parameters of a unit; calculating a frequency deviation amount; calculating to obtain the corresponding electromagnetic power variation during primary frequency modulation and taking the electromagnetic power variation as the control quantity of the primary frequency modulation of the target variable-speed pumped storage unit to finish the primary frequency modulation; in the primary frequency modulation process, the optimal target opening value of the water turbine on the primary motor side of the target variable-speed pumped storage unit working under the current water head and the current power set value is kept, and the output on the primary motor side is changed only through the change of the rotating speed of the water turbine and the change of the flow of the water turbine. However, the prior art 1 has the following disadvantages: the frequency converter is fast but the capacity is little, and the speed regulator control water gate regulation speed is slow and there is the water hammer effect, and the two simultaneous operation can lead to unable balanced two regulation modes, and control effect can not reach the best, still has the risk of restricting each other even inducing the vibration, easily produces the vibration.
Disclosure of Invention
In order to solve the defects in the prior art, the application provides a primary frequency modulation quick response method based on a variable-speed pumped storage unit, and the quick primary frequency modulation effect of the unit can be realized by utilizing the power quick response of the variable-speed pumped storage unit, so that the reliability of system operation is greatly improved. In order to achieve the above object, the present invention adopts the following technical scheme:
a primary frequency modulation quick response method based on a variable-speed pumped storage unit,
the method comprises the following steps:
step 1: collecting real-time operation parameters of the variable-speed pumped storage unit in real time;
step 2: calculating the frequency deviation according to the parameters acquired in the step 1;
step 3: when the frequency deviation is greater than the set value, the PI control is performed, an active power deviation signal is output and transmitted to a speed regulating system, the opening degree of the guide vane is adjusted, the frequency deviation is reduced, and when the frequency deviation is less than or equal to the set value, the step 4 is performed; if the frequency deviation is smaller than or equal to the set value, skipping step 3 and directly switching to step 4;
step 4: when the frequency deviation is smaller than or equal to the set value, the PI control is carried out, the output active power deviation signal is transmitted to the frequency converter, and the primary frequency modulation is completed through the frequency converter, so that the quick primary frequency modulation of the unit is realized.
The present invention specifically includes the following preferred embodiments.
In one possible implementation manner, in step 1, the real-time operation parameters of the unit include: active power and frequency emitted by the machine set during operation.
In one possible implementation, in step 2, the frequency deviation value is a frequency deviation value of the grid frequency from the rated frequency.
In one possible implementation manner, in step 3, the specific step of adjusting the opening degree of the guide vane includes:
calculating the corresponding unit output of the water pump turbine according to the output power of the given variable speed pumping and accumulating unit and the real-time working head of the water pump turbine:
wherein P' is the unit output of the water pump turbine, D is the nominal diameter of the rotating wheel, G is the working water head of the water pump turbine, eta Water and its preparation method For the efficiency of the water pump turbine, P * The output power of the variable-speed pumping and accumulating unit is obtained.
In one possible implementation manner, in step 3, the specific step of adjusting the opening degree of the guide vane includes:
the unit flow with the highest corresponding efficiency is obtained based on the unit output of the water pump turbine, and the highest efficiency of the water pump turbine at the moment can be obtained based on the highest efficiency curve:
the highest efficiency curve in the comprehensive characteristics of the water pump turbine is eta Water max ＝f 1 (Q ') with a highest output curve P ' =9.81Q ' η Water max ＝f 2 (Q'), wherein η is Water max Is the highest efficiency of the water pump turbine, f 1 Is the highest efficiency curve of the water pump turbine, Q 'is the unit flow of the water pump turbine, P' is the unit output of the water pump turbine, f 2 Is the highest output curve of the water pump turbine.
In one possible implementation manner, in step 3, the specific step of adjusting the opening degree of the guide vane includes:
based on the efficiency peak top curve n' =f 0 (Q′)|η Water and its preparation method ＝η Water max I, the unit flow with highest efficiency, calculating to obtain the corresponding optimal unit rotating speed,
wherein n' is the unit rotation speed of the water pump turbine, f 0 The peak top curve of the efficiency is that Q' is the unit flow of the water pump turbine, eta Water and its preparation method Efficiency of water pump turbine, eta Water max The maximum efficiency of the water pump turbine is achieved.
In one possible implementation manner, in step 3, the specific step of adjusting the opening degree of the guide vane includes:
based onCalculating the optimal rotating speed of the water pump turbine to be +.>
Wherein n' is the unit rotation speed of the water pump turbine, n r For the rotation speed of the generator motor, D is the nominal diameter of the rotating wheel, H is the working water head of the water pump turbine, n ref Is the optimal rotating speed of the water pump turbine.
In one possible implementation manner, in step 3, the specific step of adjusting the opening degree of the guide vane includes:
based on the curve mu of the opening degree of the guide vane 0 ＝f 3 (Q') and the highest efficiency of the water pump turbine corresponding to the unit output forceThe corresponding opening degree of the guide vane of the water pump turbine is calculated and obtained,
wherein mu 0 Is the opening degree of a guide vane of the water pump turbine, Q' is the unit flow of the water pump turbine, f 3 Is a guide vane opening curve of the water pump turbine.
A primary frequency modulation fast response system comprising: a real-time operating parameter acquisition module, a frequency deviation amount calculation module, a frequency deviation amount judgment module, a guide vane opening adjustment module and a frequency converter frequency modulation module,
the real-time running parameter acquisition module of the unit acquires real-time running parameters of the variable-speed pumped storage unit in real time, builds a unit model, and accesses the unit model into a power grid for running simulation;
the frequency deviation amount calculation module calculates the frequency deviation amount according to the acquisition parameters of the real-time operation parameter acquisition module of the unit;
the frequency deviation amount judging module judges whether the frequency deviation amount is larger than a set value, if the frequency deviation amount is larger than the set value, the control module is switched to the guide vane opening adjusting module, the PI control is carried out, an active power deviation signal is output and is transmitted to the speed regulating system, the guide vane opening is adjusted, the frequency deviation amount is reduced, and when the frequency deviation amount is smaller than or equal to the set value, the control module is switched to the frequency converter frequency modulation module; if the frequency deviation is smaller than or equal to the set value, skipping over the guide vane opening adjusting module, and directly transferring to the frequency modulation module of the frequency converter;
when the frequency deviation is smaller than or equal to the set value, the frequency modulation module is switched into the frequency converter, the PI control is carried out, the output active power deviation signal is transmitted to the frequency converter, the primary frequency modulation is completed through the frequency converter, and the quick primary frequency modulation of the unit is realized.
The variable-speed pumping and accumulating unit can take part in frequency control by taking frequency as an input signal according to the system frequency change, and when the frequency change is smaller than or equal to a set value, an output active power deviation signal is transmitted to a frequency converter to adjust the output active power through PI control, so that primary frequency modulation is directly completed; when the frequency change is greater than a set value, an active power deviation signal is output through PI control, the signal is firstly injected into a speed regulating system, the opening degree of a guide vane is firstly adjusted according to an optimal rotation speed tracking principle to enable the frequency deviation to be smaller than or equal to the set value, and then active output frequency modulation is quickly adjusted through a frequency converter.
When the machine set is put into frequency modulation control, for example, when the system power is lacked, responding to the frequency change, the frequency modulation gives out an instruction of increasing the power (when the frequency change is larger than a set value), the increased dPref is added with the initial power set value Pref, through the active deviation amount PI control, a corresponding optimal rotating speed target is given through an optimal rotating speed tracking principle, the corresponding guide vane opening degree is obtained through a speed regulator, the frequency deviation is smaller than or equal to the set value, then the active power is regulated through a frequency converter, and the power setting of the active control of the frequency converter is regulated. The two are matched, so that oscillation is avoided, and the quick primary frequency modulation effect of the unit is realized. In addition, the primary frequency modulation capacity of the conventional pumped storage unit after being connected with a power grid is compared.
The beneficial effect that this application reached:
1. the invention is applicable to the condition that the frequency fluctuation is caused by load fluctuation when the power grid operates, can realize primary frequency modulation, and effectively improves the reliability of safe and stable operation of the power grid.
2. The output active regulation of the conventional pumped storage unit can only be completed by regulating the mechanical input power through a speed regulator, and the flow rate of the water flowing through the water pump and the water turbine is changed to control the frequency within a target range, so that the regulation time is long, and the reaction speed is low. The variable speed pumping and accumulating unit plays an important role in the power system by virtue of flexible and reliable operation characteristics, and the active power adjusting process belongs to an electrical process, so that the response speed is high.
3. For a conventional pumped storage unit, because the rotating speed is constant, the primary frequency modulation capability is poor, when the water head is changed, the unit rotating speed of the water pump turbine is changed, and when the unit rotating speed deviates from the optimal unit rotating speed, the unit efficiency is reduced. The variable speed pumping and accumulating unit utilizes the advantage of adjustable rotating speed of the doubly-fed induction motor, so that the water pump turbine can always work at the optimal unit rotating speed, and the running efficiency of the unit is improved.
4. Compared with a conventional pumping and storage unit, the variable-speed pumping and storage unit has the advantages that the frequency modulation speed is higher, more power shortage can be borne, and the stability and the adaptability to a system are better.
5. The invention adopts two frequency modulation modes: when the frequency change is smaller than or equal to a set value, the PI control is carried out, an active power deviation signal is output and is transmitted to a frequency converter, and the possibility of oscillation in the frequency modulation process is reduced; when the frequency change is greater than the set value, the PI control is performed, an active power deviation signal is output and transmitted to a speed regulation system, the speed regulation system is utilized to enable the frequency deviation to be smaller than or equal to the set value, and then the frequency converter is utilized to quickly respond, so that primary frequency modulation is realized, and oscillation is avoided.
Drawings
FIG. 1 is a flow chart of the frequency modulation action of the present invention;
FIG. 2 is a general block diagram of an electromechanical transient model of the variable speed pumped storage unit of the present invention;
FIG. 3 is a schematic diagram of a frequency converter control model of the variable speed pumped-storage unit of the present invention;
FIG. 4 is a schematic diagram of a three machine nine node power grid system based on BPA of the present invention;
FIG. 5 is a graph of frequency deviation of a 6MW time-varying pumped-storage unit of the present invention;
FIG. 6 is a graph of frequency deviation of a 6MW frequent pumped-storage unit of the present invention;
FIG. 7 is a graph of the frequency deviation of a variable speed pumped-storage unit at 25MW of a cutter in accordance with the present invention;
fig. 8 is a graph of the frequency deviation of a conventional pumped-storage unit at 25MW of cutter.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described herein are merely some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present invention.
As shown in FIG. 1, the primary frequency modulation quick response method based on the variable-speed pumped storage unit comprises the following steps of:
step 1: collecting real-time operation parameters of the unit in real time;
the operating parameters include: and when the power and frequency of the active power and frequency generated by the unit are operated, a variable-speed pumped storage unit model is built in a PSD-BPA program, a three-machine nine-node power grid system is built, and the unit is connected into a power grid to perform operation simulation.
Step 2: calculating the frequency deviation according to the parameters acquired in the step 1;
acquiring system frequency, when the system frequency deviates, indicating the power shortage of the unit system, switching in frequency modulation control at the moment, responding to frequency change, and setting the rated frequency to 50Hz, when the frequency is lower than 50Hz, indicating the power shortage of the system, combining the reference frequency with the operating frequency to obtain the frequency deviation value of the power grid frequency and the rated frequency, and obtaining the output active power deviation dP through PI (pro-Integral) control ref 。
Step 3: when the frequency deviation is greater than the set value, the PI control is carried out, an active power deviation signal is output and transmitted to a speed regulating system, according to the optimal rotation speed tracking principle, the opening degree of a guide vane is regulated by a speed regulator to enable the frequency deviation to be smaller than or equal to the set value, and then the step 4 is carried out; if the frequency deviation is smaller than or equal to the set value, skipping step 3 and directly switching to step 4;
in response to frequency change in system power shortage, frequency modulation gives instruction of increasing power, which increases dP ref And the initial power set point P ref The addition gives, on the one hand, a deviation PI control of the active power in such a way that it acts on the increase of the electromagnetic power PE, and on the other hand, by means of a power-speed curve, a corresponding optimum speed target W ref And the corresponding opening degree of the guide vane is obtained through a speed regulator and an actuating mechanism, and then the corresponding mechanical power PM is obtained through a water pump turbine.
Step 4: when the frequency deviation is smaller than or equal to the set value, the PI control is carried out, the output active power deviation signal is transmitted to the frequency converter, and then the frequency modulation of the active output is quickly regulated through the frequency converter, so that oscillation is avoided.
The variable speed pumping and accumulating unit utilizes the advantage of adjustable rotating speed of the doubly-fed induction motor, when the frequency fluctuation occurs in the power grid, the optimal unit rotating speed of the water pump water turbine is calculated, the opening degree of the guide vane is adjusted through the speed regulator of the water pump water turbine, the active power is adjusted through the alternating current excitation system, and finally the primary frequency modulation of the unit is realized.
To enable the water pump turbine to work under the optimal efficiency, the unit output force at the moment is calculated according to the output power of the current variable speed pumping and accumulating unit and the working water head of the water pump turbine, and then the unit flow rate with the highest efficiency is calculated according to the comprehensive characteristics of the water pump turbine, so that the corresponding optimal unit rotating speed is calculated, and the optimal rotating speed of the water pump turbine is obtained. The method comprises the following specific steps:
(1) Calculating the corresponding unit output of the water pump turbine according to the output power of the given variable speed pumping and accumulating unit and the real-time working head of the water pump turbine:
wherein P' is the unit output of the water pump turbine, D is the nominal diameter of the rotating wheel, H is the working water head of the water pump turbine, eta Water and its preparation method For the efficiency of the water pump turbine, P * The output power of the variable-speed pumping and accumulating unit is obtained.
(2) According to the highest efficiency curve eta in the comprehensive characteristics of the water pump turbine Water max ＝f 1 (Q ') obtaining the highest output curve P ' =9.81Q '. Eta. Water max ＝f 2 (Q'), wherein η is Water max Is the highest efficiency of the water pump turbine, f 1 Is the highest efficiency curve of the water pump turbine, Q 'is the unit flow of the water pump turbine, P' is the unit output of the water pump turbine, f 2 Is the highest output curve of the water pump turbine.
Then, the unit flow rate with the highest corresponding efficiency is obtained according to the unit output of the water pump turbine obtained in the step (1), and the highest efficiency of the water pump turbine at the moment is obtained according to the highest efficiency curve.
(3) According to the efficiency peak top curve n' =f 0 (Q′)|η Water and its preparation method ＝η Water max And (3) calculating the corresponding optimal unit rotating speed from the unit flow obtained in the step (2), wherein n' is the unit rotating speed of the water pump turbine, and f 0 The peak top curve of the efficiency is that Q' is the unit flow of the water pump turbine, eta Water and its preparation method Efficiency of water pump turbine, eta Water max The maximum efficiency of the water pump turbine is achieved.
(4) According toThe optimal rotation speed of the water pump turbine is +.>Wherein n' is the unit rotation speed of the water pump turbine, n r For the rotation speed of the generator motor, D is the nominal diameter of the rotating wheel, H is the working water head of the water pump turbine, n ref Is the optimal rotating speed of the water pump turbine.
(5) According to the curve mu of the opening degree of the guide vane 0 ＝f 3 (Q') calculating the corresponding opening degree of the guide vane BN of the water pump turbine from the unit flow obtained in the step (2), wherein mu is calculated 0 Is the opening degree of a guide vane of the water pump turbine, Q' is the unit flow of the water pump turbine, f 3 Is a guide vane opening curve of the water pump turbine.
(6) And adjusting the opening degree of the guide vane of the water pump turbine according to the obtained optimal rotating speed and the guide vane opening degree instruction, so as to realize the speed regulation of the water pump turbine.
According to the specific steps of the adjusting process, the optimal rotation speed tracking of the water pump turbine mainly follows the curve track of the peak top of the efficiency of the water pump turbine, and the tracking process needs to know the conditions including:
efficiency peak top curve n' =f of water pump turbine 0 (Q′)|η Water and its preparation method ＝η Water mac I, highest efficiency curve eta 1 (Q') Water max Maximum output curve P' =f 2 (Q') and the vane opening Curve mu 0 ＝f 3 (Q') can be found from the comprehensive characteristics of the pump turbine.
The frequency converter part is controlled as follows:
the alternating current excitation system of the variable speed pumping and accumulating unit can rapidly control active power and reactive power output by the stator side of the generator motor, and rapid response of power is achieved.
The frequency converter control of the doubly-fed motor mainly comprises a machine side frequency converter control and a network side frequency converter control, wherein the machine side frequency converter mainly has the function of controlling the rotor voltage of the motor to realize active and reactive power control, and the model mainly comprises three parts, namely an active power control part, a reactive power control part and a rotor voltage control part.
The active power control part compares the motor rotation speed omega with a reference value omega ref Obtaining deviation, and obtaining an active power reference value P through PI control ref Further control the active power,
under the electromechanical transient simulation condition, the current control of the inner ring can be ignored, only the active and reactive control of the outer ring is reserved, the machine side and the network side are not needed to be distinguished (the rapid charging and discharging process of the direct-current capacitor is ignored), the whole frequency converter is modeled, and the rapid response of power is realized.
The variable-speed pumping and accumulating unit can take part in frequency control by taking frequency as an input signal according to the system frequency change, and when the frequency change is less than or equal to 0.1Hz, an output active power deviation signal is transmitted to a frequency converter to adjust the output active power through PI control, so that primary frequency modulation is directly completed; when the frequency change is greater than 0.1Hz, an active power deviation signal is output through PI control, according to the optimal rotation speed tracking principle, the opening degree of the guide vane is adjusted by the speed regulator to enable the frequency deviation to be smaller than or equal to 0.1Hz, and then active output frequency modulation is quickly adjusted through the frequency converter.
When the machine set is put into frequency modulation control, for example, when the system power is lack, the frequency modulation gives a command for increasing the power, namely the increased dP, in response to the frequency change (when the frequency change is greater than 0.1 Hz) ref And the initial power set point P ref Adding, and providing a corresponding optimal rotation speed target omega by an optimal rotation speed tracking principle through active deviation PI control ref The corresponding opening degree of the guide vane is obtained through the speed regulator, so that the frequency deviation is smaller than or equal to 0.1Hz, and the frequency modulation of the active output is quickly regulated by the frequency converter. Matched with each otherThe oscillation is avoided, and the quick primary frequency modulation effect of the unit is realized.
Example 1
As shown in FIG. 2, FIG. 2 is a general block diagram of a variable speed pumped storage unit electromechanical transient model.
In the figure, V t For the terminal voltage, P gen 、Q gen Respectively the active power and the reactive power of the unit, delta P is the power variation given by frequency modulation control, Q ref Power command, ω, for voltage regulation control gen 、P m The rotation speed and the mechanical power of the generator, omega ref 、Y ref Respectively the optimal rotating speed and the optimal guide vane opening reference value, I' pref 、I′ qref 、I pref 、I qref And controlling active and reactive current instructions before and after amplitude limiting for the frequency converter respectively.
According to the invention, PSD-BPA software is utilized to simulate a three-machine nine-node power grid system to verify the primary frequency modulation capability of a variable-speed pumping and accumulating unit, and a generator 1 and a generator 2 are conventional synchronous machines (the generator 2 is divided into two parts and is used for cutting machine to do frequency modulation simulation); the generator 3 is a variable speed pumping and accumulating unit, and can be modified into a conventional pumping and accumulating unit, and is installed with 100MW as shown in figure 3.
The primary frequency modulation of the variable-speed pumped storage unit in the power grid can be performed by adopting the primary frequency modulation rapid response method based on the variable-speed pumped storage unit, the variable-speed pumped storage unit is installed at the generator 3 and can be transformed into a conventional pumped storage unit, and finally simulation is performed, so that the primary frequency modulation effect of the variable-speed pumped storage unit is compared, and the protection of the power grid is realized. The specific implementation steps are shown in fig. 1.
Step 1: acquiring real-time operation parameters of the unit in real time;
and constructing a variable-speed pumped storage unit model in a PSD-BPA program, and constructing a three-machine nine-node power grid system, and accessing the unit into a power grid for operation simulation.
Step 2: calculating the frequency deviation according to the parameters obtained in the step 1;
when the machine set is put into frequency modulation control, the generator 2 cuts off 6MW and 25MW respectively, and responds toFrequency modulation gives instructions for increasing power at varying frequencies, which increases dP ref And the initial power set point P ref And (5) adding. The generator 2 is switched off, the system has power shortage, the frequency is reduced, the reference rated frequency 50Hz is combined with the actual frequency of the power grid to obtain a frequency deviation value, and the frequency deviation value is subjected to PI control to obtain the output active power deviation dP ref 。
Step 3: when the frequency deviation is greater than 0.1Hz, the PI control is carried out, an active power deviation signal is output and transmitted to a speed regulating system, the opening degree of a guide vane is regulated by a speed regulator according to the optimal rotation speed tracking principle to ensure that the frequency deviation is less than or equal to 0.1Hz, and then the step 4 is carried out; when the frequency change is less than or equal to 0.1Hz, directly transferring to the step 4;
issue an instruction to increase power, which increases dP ref And the initial power set point P ref The addition is performed by the active deviation PI control.
Step 4: when the frequency change is less than or equal to 0.1Hz, the output active power deviation signal is transmitted to the frequency converter through PI control, and primary frequency modulation is directly completed through the frequency converter;
firstly, giving a corresponding optimal rotating speed target omega by an optimal rotating speed tracking principle ref And the corresponding opening degree of the guide vane is obtained through the speed regulator, so that the frequency deviation is smaller than or equal to 0.1Hz, and the active output frequency modulation is quickly regulated by the frequency converter, so that oscillation is avoided.
The variable-speed pumping and accumulating unit can take part in frequency control by taking frequency as an input signal according to the system frequency change, and when the frequency change is less than or equal to 0.1Hz, an output active power deviation signal is transmitted to a frequency converter to adjust the output active power through PI control, so that primary frequency modulation is directly completed; when the frequency change is greater than 0.1Hz, an active power deviation signal is output through PI control, the opening of the guide vane is adjusted by the speed regulator to enable the frequency deviation to be smaller than or equal to 0.1Hz, and then the active output frequency modulation is quickly adjusted through the frequency converter.
When the machine set is put into frequency modulation control, for example, when the system power is lack, the frequency modulation gives a command for increasing the power, namely the increased dP, in response to the frequency change (more than 0.1 Hz) ref From the initial pointPower setpoint P of (2) ref Adding, and providing a corresponding optimal rotation speed target omega by an optimal rotation speed tracking principle through active deviation PI control ref And the corresponding opening degree of the guide vane is obtained through the speed regulator, so that the frequency deviation is smaller than or equal to 0.1Hz, and then the active power is regulated through the frequency converter, so that the power setting of the active control of the frequency converter is regulated. The two are matched, so that oscillation is avoided, and the quick primary frequency modulation effect of the unit is realized.
Step 5, comparing and analyzing the primary frequency modulation effect of the conventional pumped storage unit
The generator 3 is transformed into a conventional pumped storage unit, the conventional pumped storage unit has no optimal rotation speed tracking function, and an alternating current excitation system, so that quick response adjustment cannot be realized.
According to the experimental steps, the experimental results are as follows:
firstly, the simulation generator 2 is cut into 6MW, the variable speed and the conventional pumping and accumulating unit play a primary frequency modulation role, and the speed of the variable speed pumping and accumulating unit participating in frequency modulation is faster, as shown in fig. 4 and 5; when the generator 2 is switched to 25MW, the conventional pumped storage unit does not have primary frequency modulation capability, and the variable-speed pumped storage unit can continue to perform primary frequency modulation, as shown in fig. 6 and 7. In summary, both the variable speed pumping unit and the conventional pumping unit have primary frequency modulation capability. Compared with a conventional pumping and storage unit, the variable-speed pumping and storage unit has the advantages that the frequency modulation speed is higher, more power shortage can be borne, and the stability and the adaptability to a system are better.
While the applicant has described and illustrated the embodiments of the present invention in detail with reference to the drawings, it should be understood by those skilled in the art that the above embodiments are only embodiments of the present invention, and the detailed description is only for the purpose of helping the reader to better understand the spirit of the present invention, and not to limit the scope of the present invention, but any improvements or modifications based on the spirit of the present invention should fall within the scope of the present invention.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (9)
1. A primary frequency modulation quick response method based on a variable-speed pumped storage unit is characterized by comprising the following steps of:
the method comprises the following steps:
step 1: collecting real-time operation parameters of the variable-speed pumped storage unit in real time;
step 2: calculating the frequency deviation according to the parameters acquired in the step 1;
step 3: when the frequency deviation is greater than the set value, the PI control is performed, an active power deviation signal is output and transmitted to a speed regulating system, the opening degree of the guide vane is adjusted, the frequency deviation is reduced, and when the frequency deviation is less than or equal to the set value, the step 4 is performed; if the frequency deviation is smaller than or equal to the set value, skipping step 3 and directly switching to step 4;
step 4: when the frequency deviation is smaller than or equal to the set value, the PI control is carried out, the output active power deviation signal is transmitted to the frequency converter, and the primary frequency modulation is completed through the frequency converter, so that the quick primary frequency modulation of the unit is realized.
2. The variable speed pumped storage unit based primary frequency modulation rapid response method of claim 1, wherein the method comprises the steps of:
in step 1, the real-time operation parameters of the unit include: active power and frequency emitted by the machine set during operation.
3. The variable speed pumped storage unit based primary frequency modulation rapid response method of claim 1, wherein the method comprises the steps of:
in step 2, the frequency deviation is the frequency deviation between the grid frequency and the rated frequency.
4. The variable speed pumped storage unit based primary frequency modulation rapid response method of claim 1, wherein the method comprises the steps of:
in step 3, the specific step of adjusting the opening of the guide vane comprises the following steps:
calculating the corresponding unit output of the water pump turbine according to the output power of the given variable speed pumping and accumulating unit and the real-time working head of the water pump turbine:
wherein P' is the unit output of the water pump turbine, D is the nominal diameter of the rotating wheel, H is the working water head of the water pump turbine, eta Water and its preparation method For the efficiency of the water pump turbine, P * The output power of the variable-speed pumping and accumulating unit is obtained.
5. The variable speed pumped storage unit based rapid response method for primary frequency modulation of claim 4, wherein:
in step 3, the specific step of adjusting the opening of the guide vane comprises the following steps:
the unit flow with the highest corresponding efficiency is obtained based on the unit output of the water pump turbine, and the highest efficiency of the water pump turbine at the moment can be obtained based on the highest efficiency curve:
the highest efficiency curve in the comprehensive characteristics of the water pump turbine is eta Water max ＝f 1 (Q ') with a highest output curve P ' =9.81Q ' η Water max ＝f 2 (Q'), wherein η is Water max Is the highest efficiency of the water pump turbine, f 1 Is the highest efficiency curve of the water pump turbine, Q 'is the unit flow of the water pump turbine, P' is the unit output of the water pump turbine, f 2 Is the highest output curve of the water pump turbine.
6. The variable speed pumped storage unit based rapid response method for primary frequency modulation of claim 5, wherein:
in step 3, the specific step of adjusting the opening of the guide vane comprises the following steps:
based on the efficiency peak top curve n' =f 0 (Q′)|η Water and its preparation method ＝η Water max I, the unit flow with highest efficiency, calculating to obtain the corresponding optimal unit rotating speed,
wherein n' is the unit rotation speed of the water pump turbine, f 0 The peak top curve of the efficiency is that Q' is the unit flow of the water pump turbine, eta Water and its preparation method Efficiency of water pump turbine, eta Water max The maximum efficiency of the water pump turbine is achieved.
7. The variable speed pumped storage unit based rapid response method for primary frequency modulation of claim 6, wherein:
in step 3, the specific step of adjusting the opening of the guide vane comprises the following steps:
based onCalculating the optimal rotating speed of the water pump turbine to be +.>
Wherein n' is the unit rotation speed of the water pump turbine, n r For the rotation speed of the generator motor, D is the nominal diameter of the rotating wheel, H is the working water head of the water pump turbine, n ref Is the optimal rotating speed of the water pump turbine.
8. The variable speed pumped storage unit based rapid response method for primary frequency modulation of claim 7, wherein:
in step 3, the specific step of adjusting the opening of the guide vane comprises the following steps:
based on the curve mu of the opening degree of the guide vane 0 ＝f 3 (Q') and the unit flow rate with highest efficiency corresponding to the unit output force of the water pump turbine are calculatedTo the corresponding opening degree of the guide vane of the water pump turbine,
wherein mu 0 Is the opening degree of a guide vane of the water pump turbine, Q' is the unit flow of the water pump turbine, f 3 Is a guide vane opening curve of the water pump turbine.
9. A rapid response system for a variable speed pumped storage unit based rapid response method for a frequency modulation, as defined in claims 1 to 8, comprising: the device comprises a unit real-time operation parameter acquisition module, a frequency deviation amount calculation module, a frequency deviation amount judgment module, a guide vane opening adjustment module and a frequency converter frequency modulation module, and is characterized in that:
the real-time running parameter acquisition module of the unit acquires real-time running parameters of the variable-speed pumped storage unit in real time, builds a unit model, and accesses the unit model into a power grid for running simulation;
the frequency deviation amount calculation module calculates the frequency deviation amount according to the acquisition parameters of the real-time operation parameter acquisition module of the unit;
the frequency deviation amount judging module judges whether the frequency deviation amount is larger than a set value, if the frequency deviation amount is larger than the set value, the control module is switched to the guide vane opening adjusting module, the PI control is carried out, an active power deviation signal is output and is transmitted to the speed regulating system, the guide vane opening is adjusted, the frequency deviation amount is reduced, and when the frequency deviation amount is smaller than or equal to the set value, the control module is switched to the frequency converter frequency modulation module; if the frequency deviation is smaller than or equal to the set value, skipping over the guide vane opening adjusting module, and directly transferring to the frequency modulation module of the frequency converter;
when the frequency deviation is smaller than or equal to the set value, the frequency modulation module is switched into the frequency converter, the PI control is carried out, the output active power deviation signal is transmitted to the frequency converter, the primary frequency modulation is completed through the frequency converter, and the quick primary frequency modulation of the unit is realized.
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