Automatic online identification method for multi-stage flexible self-adaptive control parameters of variable-speed pumped storage AES (advanced encryption standard)

Abstract

The invention discloses a variable-speed pumped storage AES multi-stage flexible adaptive control parameter automatic online identification method, which comprises the following steps of: S1, reading a unit working stage signal, and judging the current working stage of an MSC (Mobile Switching Center); s2, based on the current working stage of the MSC, adopting a three-phase pseudo-random sequence to excite a secondary measurement signal of MSC controller hardware in a loop; s3, identifying proportion and integral parameters of the MSC controller by adopting a particle swarm algorithm; s4, if the working stage of the unit changes and is not the shutdown stage, the step S1 is executed, and parameter identification of the next working stage is started; and S5, when the working stage of the unit is a shutdown stage, quitting the identification program. A three-phase pseudo-random sequence is adopted to excite a secondary side measurement signal of the MSC controller, so that operation on an intermediate variable of the controller is avoided, and the engineering practicability is enhanced; according to the control parameter identification method based on simultaneous excitation of the inner ring and the outer ring of the controller, the step-by-step identification problem of the cascaded PI controller is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of variable speed pumped storage AC excitation system control, and more specifically to an online automatic identification method for multi-stage flexible adaptive control parameters of a variable speed pumped storage AC excitation controller. Background Art

[0002] With the increasing penetration rate of distributed power sources, fixed-speed pumped storage can no longer meet the needs of flexible regulation of new power systems. Flexible control of variable-speed pumped storage (VSPS) has become an urgent need. AC excitation system (AES) is the key equipment for flexible control of variable-speed units. Currently, there is no reasonable and accurate controller parameter identification method.

[0003] In the VSPS multi-stage flexible control process, the water heads and geographical conditions of different units are different, resulting in different electrical parameters between units and different AES controller parameters; at the same time, due to the different physical characteristics and control objectives of AES in different stages of a single unit, the AES control model and controller parameters will change with the changes in the unit stage. Considering that the AES controller has the physical characteristics of adaptive control parameters, adaptive control parameter identification is an important part of designing the AES multi-stage flexible adaptive control strategy. Its rationality and accuracy are the prerequisites for AES controller design and unit refined simulation.

[0004] On the other hand, AES is a multivariable, strongly coupled, high-order nonlinear system, and its control performance is closely related to the operating parameters of the generator motor. Long-term operation or aging of the generator motor will cause changes in the generator motor's own electrical parameters. If the AES controller parameter changes are not timely grasped, the use of expired control parameters will not be able to accurately simulate the unit's transient process. Therefore, automatic identification of AES controller parameters is a prerequisite for realizing precise simulation research of the unit.

[0005] AES controller parameter identification refers to the process of determining the AES controller model parameters through experiments and data analysis in the design of VSPS unit automatic control system. These parameters are used in the design of AES controller to ensure that the system operates according to the predetermined performance indicators.

[0006] The key to AES controller parameter identification is to select the appropriate model structure and identification algorithm, as well as to ensure the quality of data. In practical applications, AES is affected by nonlinearity, multivariables, time-varying, uncertainty and external interference, all of which increase the difficulty of identification. Therefore, AES controller parameter identification needs to be automatically adjusted and optimized online in combination with the specific conditions of the VSPS unit. Summary of the invention

[0007] To solve the above problems, the present invention applies for a method for automatic online identification of multi-stage flexible adaptive control parameters of an AES controller of a variable-speed pumped storage unit, which is not only suitable for the AES controller parameter identification of units with different water heads and geographical conditions, but also suitable for the online automatic identification of flexible adaptive control parameters of a single unit AES at different stages.

[0008] In a first aspect, the present invention proposes an online identification method based on superimposing an excitation signal on the secondary measurement signal side, wherein the inner loop and the outer loop of the AES controller simultaneously superimpose a three-phase pseudo-random sequence excitation.

[0009] In a second aspect, the present invention proposes a method for dividing different stages of the power generation process and the pumping process of a VSPS unit.

[0010] In a third aspect, the present invention proposes an AES-MSC controller parameter identification method based on the least squares method to achieve intelligent identification of AES-MSC controller parameters.

[0011] In a fourth aspect, the present invention proposes a multi-stage flexible adaptive control parameter identification method of an AES-MSC controller based on a finite state machine to realize an automatic parameter identification function of an AES-MSC controller.

[0012] In a fifth aspect, the present invention proposes a multi-stage flexible adaptive control parameter identification method for an AES-MSC controller based on hardware-in-the-loop, thereby realizing the identification function of the AES-MSC controller parameters under hardware-in-the-loop.

[0013] An automatic online identification method for multi-stage flexible adaptive control parameters of a variable speed pumped storage AES, wherein the unit is implemented by a real-time simulator except for an MSC controller which is a physical object, and the method comprises: S1, reading the unit working stage signal to determine the current working stage of the MSC; S2, based on the current working stage of the MSC, using a three-phase pseudo-random sequence to stimulate the secondary measurement signal of the MSC controller hardware-in-loop; S3, using a particle swarm algorithm to identify the proportional and integral parameters of the MSC controller; S4, when the unit working stage changes and is not a shutdown stage, jumping to S1 and starting parameter identification for the next working stage; S5, when the unit working stage is a shutdown stage, exiting the identification program.

[0014] After identifying the proportional and integral parameters of the MSC controller, interrupt the communication between the MSC controller and the simulator and shield the MSC controller; according to the unit working stage signal, call the hardware-in-the-loop simulation model of the current working stage of the MSC based on the finite state machine principle to verify the parameter identification results; if the simulation result is wrong, jump to S3 for secondary identification; if the simulation result is correct, save the MSC controller parameter identification results.

[0015] The present invention has at least the following advantages or beneficial effects: it is not only suitable for the identification of AES controller parameters of units with different water heads and geographical conditions, but also suitable for the automatic identification of flexible adaptive control parameters of AES of a single unit at different stages, and has good compatibility; the superimposed three-phase pseudo-random sequence excitation method based on the secondary side avoids the operation of the intermediate variables of the controller, thereby enhancing the engineering practicality; the control parameter identification method based on the simultaneous excitation of the inner loop and the outer loop of the AES controller effectively solves the step-by-step identification problem of the cascade PI controller; the automatic identification method of AES multi-stage flexible control parameters based on the finite state machine effectively solves the problem of segmented identification; the online identification of control parameters based on hardware-in-the-loop avoids the disturbance operation of the unit and improves the safety of parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the VSPS unit structure.

[0017] Figure 2 This is a schematic diagram of the multi-stage conversion process of the VSPS unit power generation process.

[0018] Figure 3 It is a schematic diagram of the multi-stage conversion of the pumping process of the VSPS unit.

[0019] Figure 4 This is the control model block diagram of the AES-MSC steady-state power generation stage of the VSPS unit.

[0020] Figure 5 It is a schematic diagram of hardware-in-the-loop simulation for automatic identification of AES-MSC multi-stage flexible adaptive control parameters of VSPS units.

[0021] Figure 6 It is a schematic diagram of a three-phase pseudo-random sequence excitation method for an AES-MSC controller of a VSPS unit provided in one embodiment of the present invention.

[0022] Figure 7 The present invention is a multi-stage parameter automatic identification flow chart of the AES-MSC controller of the VSPS unit based on the finite state machine. DETAILED DESCRIPTION

[0023] Figure 1 The structure of the VSPS unit is shown. The unit is extremely complex and includes a monitoring system, a coordination controller, a generator motor, an AC excitation system (AES), a speed governor and its control system, a reversible pump-turbine, an upper reservoir, a lower reservoir, a water diversion system and a surge tank. The VSPS unit is a water-machine-electrical-control coupled system with multi-time scale, multi-stage and strongly coupled physical characteristics.

[0024] The AC excitation system (AES) includes the machine-side converter (AES-MSC) and its controller and the grid-side converter (AES-GSC) and its controller. The target of the AES-GSC controller is the DC voltage of the capacitor, so the AES-GSC controller parameters remain unchanged in different stages; the control target of the VSPS unit is different in different stages, so the AES-MSC controller parameters are also different in different stages, with multi-stage adaptive physical characteristics.

[0025] Since the parameter identification methods of the AES-MSC controller and the AES-GSC controller are similar, this embodiment introduces the parameter identification method of the AES-MSC controller, and the parameter identification method of the AES-GSC controller is not described in detail.

[0026] like Figure 2 As shown in the figure, the power generation process of the VSPS unit includes multiple stages: shutdown, power generation start-up, no-load voltage build-up, flexible grid connection, output increase, steady-state power generation, load shedding and electrical braking. During the power generation start-up stage, the AES-GSC starts to charge the DC bus, but the AES-MSC does not work. Except for shutdown and power generation start-up, the AES-MSC is in working state in other stages.

[0027] like Figure 3 As shown in the figure, the AES pumping process of the VSPS unit includes multiple stages: shutdown, pumping start, electric synchronization, steady-state pumping, speed reduction and electrical braking. When the pumping start adopts the SFC mode, the AES-GSC starts to charge the DC bus, but the AES-MSC does not work; when the pumping start adopts the self-starting mode, the AES-GSC and AES-MSC are both in working state, and the AES-MSC is in working state in other stages except the shutdown and SFC start mode.

[0028] According to the working principle of multi-stage flexible adaptive control of VSPS units, the present invention proposes an online automatic identification method for multi-stage flexible adaptive control parameters of AES-MSC controller based on finite state machine. The method is described in detail below. According to the multi-stage working principle of AES-MSC controller of VSPS units, in the present invention, AES-MSC controller adopts a typical double closed-loop PI control framework with feedforward. The identification target of AES-MSC is the controller parameters of each stage. Taking the steady-state power generation stage as an example, the controller parameters to be identified are k p1 ~k p4 and k i1 ~k i4 , a total of 8 parameters, Figure 4 This is the control model block diagram of the AES-MSC steady-state power generation stage of the VSPS unit. The coefficients of the d-axis outer and inner loop PI controllers in the steady-state power generation stage are: k p1 ~k p2 , k i1~k i2 ; q-axis outer and inner loop PI controller coefficients: k p3 ~k p4 , k i3 ~k i4 . Figure 4 Where P and Q are active power and reactive power respectively, P * , Q * They are the set values / command values ​​for active power and reactive power respectively.

[0029] In the laboratory, you can build a Figure 5 The variable speed pumped storage unit hardware-in-the-loop experimental platform shown performs online automatic identification of the multi-stage flexible adaptive control parameters of the AC excitation controller. For example, RT-LAB can be used to establish a hardware-in-the-loop experimental platform. The hardware-in-the-loop simulation test platform is equipped with a real-time scheduling platform, a real-time simulator (such as OP5700), a central controller and a host computer. Optical fiber communication is used between the machine-side converter controller and the simulator, and the communication protocol is Aurora. The present invention performs online identification of the AES-MSC multi-stage flexible adaptive control parameters. Except for the machine-side converter controller (AES-MSC controller) of the VSPS unit, which is a real object, all others (including the grid-side converter controller) are implemented by a real-time simulator.

[0030] Considering that the AES-MSC controller takes action because the secondary side measurement circuit detects the change of the primary side electrical quantity, the measurement signal is sent to the AES-MSC controller to stimulate the controller's response. Figure 6 As shown, the present invention adopts a method of identifying the parameters of the AES-MSC controller by superimposing a three-phase pseudo-random sequence signal on the secondary side measurement signal, and this method can be directly applied to practical engineering. 1 and m 2 are two disturbances of the rotating coordinate system (three-phase pseudo-random sequence signals), which are transformed into disturbances of the three-phase stationary coordinate system (stator excitation current i sf , rotor excitation current i rf ), the perturbations of the inner and outer loops are the same. Figure 6 in,i s is the stator current, i f is the rotor current, i s ′ is the stator excitation current i sf and the stator current i s The value input to the AES-MSC controller after superposition, i′ r is the rotor excitation current i rf and rotor current i f The value input to the AES-MSC controller after superposition, u sq is the q-axis voltage component of the stator voltage, usd is the d-axis voltage component of the stator voltage, is the rotor q-axis reference current, Δu rq is the rotor q-axis voltage compensation term, The simulation results are shown in Figure 2. It is necessary to identify the proportional and integral (kp, ki) of the PI controller in this model.

[0031] The parameters of the AES-MSC controller are identified by superimposing the three-phase pseudo-random sequence signals on the secondary side measurement signals of the inner and outer loops of the AES-MSC controller, thus avoiding the problem of step-by-step identification caused by the cascade of the inner and outer loop PI controllers.

[0032] In the simulation environment, the three-phase pseudo-random sequence signals of the inner and outer loops of the AES-MSC controller are both realized by a simulator (such as OP5700).

[0033] Considering that the response time of the outer loop PI control of the AES-MSC controller is several milliseconds to tens of milliseconds, and the response time of the inner loop PI control is hundreds of microseconds to several milliseconds, and to ensure that the signal meets the continuous excitation condition, the frequency of the three-phase pseudo-random sequence signal can be 800-1200Hz.

[0034] Considering that the output limiting design value of the actual controller cannot be obtained, in order to avoid saturation nonlinearity of the controller output caused by signal excitation, the present invention adopts a method of determining the excitation signal size by 4% to 8% of the maximum value of the controller feedback input during the startup phase of the VSPS unit.

[0035] The least square method is used to identify the parameters of the AES-MSC controller. The multi-stage flexible adaptive parameter automatic identification process of the AES-MSC controller based on the finite state machine is as follows: Figure 7 As shown, the working phase signal of the VSPS unit is sent to this program by the coordination controller, and the electrical parameters of the VSPS unit itself are sent to this program by the monitoring system.

[0036] The steps of the automatic identification process of multi-stage flexible adaptive control parameters of the AES-MSC controller based on the finite state machine are as follows:

[0037] 1. Initialize the system.

[0038] 2. Read the parameters of the generator motor, including the resistance, inductance, mutual inductance, etc. of the motor stator and rotor.

[0039] 3. Read the unit working stage signal to determine the current working stage of AES-MSC.

[0040] 4. Use a three-phase pseudo-random sequence to stimulate the secondary measurement signal of the AES-MSC physical controller hardware in the loop. That is, apply a disturbance (three-phase pseudo-random sequence signal) to the identification model and obtain the simulation result. Superimpose the three-phase pseudo-random sequence signal with the stator current measurement signal and the rotor current measurement signal to obtain the stator current superposition signal i s ′ and rotor current superposition signal i′ r , change i s ′、i′ r The actual stator current and rotor current input signals of the AES-MSC controller are used to obtain the simulation results of the actual model. The PI controller parameters (kp, ki) in the identification model (AES-MSC controller) are used as the quantities to be identified.

[0041] 5. Call the particle swarm algorithm to identify the kp and ki of the AES-MSC controller. Initialize the particle speed and position, calculate the fitness function of each particle, calculate and update the local optimal value and global optimal value of the particle, update the position, speed and inertia function of the particle, calculate the population fitness variance, determine whether the algorithm converges prematurely, use the Logistic mapping equation to perform chaotic processing on the prematurely converged particles, update the particle position and speed according to the fitness sorting, and continuously perform iterative search until the maximum number of iterations is reached, and the iteration is terminated to output the optimal fitness function value.

[0042] 6. Interrupt the communication between the physical controller and the simulator, and shield the AES-MSC physical controller.

[0043] 7. According to the working phase signal of the VSPS unit, the hardware-in-the-loop simulation model of the current working phase of AES-MSC (including AES-MSC controller) is called based on the finite state machine principle to verify the parameter identification results.

[0044] 8. If the simulation result is wrong, jump to step 5 for secondary identification.

[0045] 9. The simulation results are correct, and the parameter identification results of the AES-MSC physical controller are saved.

[0046] 10. If the unit's operating phase changes and it is not a shutdown phase, jump to step 3 to start parameter identification for the next operating phase.

[0047] 11. The unit is in the shutdown phase, and the AES-MSC controller parameter automatic identification program is exited.

Claims

1. A method for automatic online identification of multi-stage flexible adaptive control parameters of variable speed pumped storage AES, characterized in that: Except for the MSC controller, which is a physical object, all other parts of the unit are implemented by a real-time simulator. The method includes: S1, read the unit working stage signal and determine the current working stage of MSC; S2, based on the current working stage of the MSC, a three-phase pseudo-random sequence is used to stimulate the secondary measurement signal of the MSC controller hardware in the loop; S3, using particle swarm algorithm to identify the proportional and integral parameters of the MSC controller; S4: If the unit's working stage changes and it is not the shutdown stage, jump to S1 and start parameter identification for the next working stage; S5. The unit's working stage is the shutdown stage, and the identification program is exited.

2. The method according to claim 1, characterized in that After identifying the proportional and integral parameters of the MSC controller, the communication between the MSC controller and the simulator is interrupted and the MSC controller is shielded; according to the unit working phase signal, the hardware-in-the-loop simulation model of the MSC current working phase is called based on the finite state machine principle to verify the parameter identification results; If the simulation result is wrong, jump to S3 for secondary identification; The simulation results are correct and the MSC controller parameter identification results are saved.

3. The method according to claim 1, characterized in that The MSC controller adopts a double closed-loop PI control architecture with feedforward.

4. The method according to claim 3, characterized in that: The MSC controller parameters are identified by superimposing three-phase pseudo-random sequence signals on the secondary side measurement signals of the inner and outer loops of the MSC controller, thus avoiding the problem of step-by-step identification caused by the cascade of the inner and outer loop PI controllers.

5. The method according to claim 4, characterized in that The three-phase pseudo-random sequence signal is superimposed on the stator current measurement signal and the rotor current measurement signal respectively to obtain the actual stator current and rotor current input signals as the MSC controller.

6. The method according to claim 1, characterized in that The pulse frequency of the pseudo-random sequence signal is 800-1200Hz.

7. The method according to claim 1, characterized in that The pulse frequency of the pseudo-random sequence signal is 1000 Hz.

8. The method according to claim 1, characterized in that: The size of the three-phase pseudo-random sequence signal is determined by using 4% to 8% of the maximum value of the MSC controller feedback input during the unit startup phase.

9. The method according to claim 1, characterized in that: The power generation process of the variable-speed pumped storage unit includes: shutdown, power generation start-up, no-load pressure building, flexible grid connection, load increase, steady-state power generation, load shedding and electrical braking. The MSC does not work during the power generation start-up and shutdown stages.

10. The method according to claim 1, characterized in that The power generation process of the variable-speed pumped storage unit includes: shutdown, power generation start-up, no-load pressure building, flexible grid connection, load increase, steady-state power generation, load shedding and electrical braking. The MSC does not work during the power generation start-up and shutdown stages.

Images