A Smooth Switching Control Method for Island Operation of a Mobile Power Generation Vehicle

Abstract

The present invention discloses a smooth switching control method for an island operation of a mobile power generation vehicle. The method subtracts the target value of the output reactive power in the grid-connected operation mode of the mobile power generation vehicle from the reactive power signal of the diesel generator output measured by the internal measurement and control module to obtain a deviation value signal of the reactive power. The voltage limit calculation module calculates a voltage deviation compensation signal, which forms an original signal of the compensation branch through the PI adjustment module. A smooth switching compensation signal and a transient response compensation signal are formed. A primary voltage correction signal is obtained, and the sum of the primary voltage correction signal and the port voltage control target value is calculated to obtain a corrected port voltage control target value. Then, the port voltage and the transient response compensation signal value are subtracted from the corrected port voltage control target value to obtain an outer-loop voltage control command of the excitation control system. The outer-loop voltage control command of the excitation control system is input into the excitation control system to complete the smooth switching control of the island operation of the mobile power generation vehicle. The present invention avoids the switching of the control loop switch, making the operation mode switching smoother.

Description

Technical Field

[0001] The present invention relates to the field of operating state control of diesel generator vehicles, and particularly to a smooth switching control method for the island operation of mobile generator vehicles. Background Art

[0002] In order to reduce the power outage time and frequency of users, mobile generator vehicles, which have the advantages of convenient access, large power supply capacity, and flexible power supply methods, have been widely used as emergency power sources in scenarios such as power outage maintenance and emergency power supply for major events in the distribution system.

[0003] The operating modes of mobile generator vehicles are divided into island operation and grid-connected operation. During island operation, the mobile generator vehicle independently bears the load power and needs to adopt a constant voltage control method. During grid-connected operation, the mobile generator vehicle injects power into the large system and needs to adopt a constant power control method. The power control methods of mobile generator vehicles are different under the two operating modes. When a mobile generator vehicle experiences a disconnection event, it is necessary to promptly switch the operating mode of the mobile generator vehicle from grid-connected operation to island operation; otherwise, phenomena such as voltage instability will occur. Therefore, to ensure the stable operation of mobile generator vehicles, the power control method must change according to the change in the operating mode of the mobile generator vehicle to avoid the phenomena of power angle and voltage instability of the mobile generator vehicle caused by incorrect power control methods. Therefore, an effective and stable smooth switching method for mobile generator vehicle islands is particularly important.

[0004] The smooth switching method for mobile generator vehicle islands includes a mobile generator vehicle island detection method and a mobile generator vehicle operating mode switching control method. Existing mobile generator vehicle island detection methods are divided into passive detection and active detection. Active detection determines whether it is in island operation through active methods such as active power disturbance and reactive power compensation. Due to the introduction of external active signals, the detection accuracy is high, but there is a problem of large delay. The greater the detection delay, the greater the deviation of the voltage and frequency of the generator from the rated value, and in severe cases, it will trigger protection and cause the generator vehicle to exit the operation. The passive detection method is simple, does not require external active signals, is easy to implement, and has low delay, and is currently widely used. In terms of the mobile generator vehicle operating mode switching control method, existing methods mainly first perform island detection and then enable the control circuit switch of the diesel generator set according to the result of the island detection to achieve the switching of the control mode. Since the island detection and the operating mode switching control are separated, when the existing method fails in island detection, the control circuit of the diesel generator set cannot timely switch the control mode, resulting in the instability of the mobile generator vehicle and posing an operating risk. Summary of the Invention

[0005] Aiming at the deficiencies of the above technologies, the present invention provides a smooth switching control method for the island operation of mobile generator vehicles, which solves the technical problem of how to organically combine island detection and operating mode switching control and avoid the operating risks generated when island detection fails.

[0006] To solve the above technical problems, the present invention provides a smooth switching control method for an island operation of a mobile power generation vehicle, including the following steps:

[0007] Step 1: Subtract the output reactive power target value Q of the mobile power generation vehicle in the grid-connected operation mode ref from the reactive power signal Q of the diesel generator output measured by the internal measurement and control module of the mobile power generation vehicle to obtain a deviation value signal of the reactive power;

[0008] Step 2: Subtract the output port voltage V t measured by the internal measurement and control module of the mobile power generation vehicle from the limited voltage V tL calculated by the voltage limiting calculation module to obtain a voltage deviation compensation signal;

[0009] Step 3: Connect the voltage deviation compensation signal to a PI adjustment module with parameters to form an original signal of the compensation branch;

[0010] Step 4: Define K C1 , K C2 as the static gain coefficient of the smooth switching compensation and the static gain coefficient of the transient response compensation respectively. Multiply the original signal of the compensation branch by K C1 , K C2 respectively to form a smooth switching compensation signal and a transient response compensation signal;

[0011] Step 5: Connect the deviation value signal of the reactive power to a PI adjustment module with parameters and smoothed switching compensation to form a primary voltage correction signal V qe ;

[0012] Step 6: Add the voltage correction signal V qe to the port voltage control target value V ref to calculate the port voltage control target value V refqe after the primary correction;

[0013] Step 7: Subtract the port voltage V refqe from the port voltage control target value V t after the primary correction and the transient response compensation signal value to obtain the outer loop voltage control command V AVR of the excitation control system;

[0014] Step 8: Output V AVR to the excitation control system to complete the smooth switching control of the island operation of the mobile power generation vehicle.

[0015] Preferably, in the step 2, the calculation formula of the voltage limiting calculation module is:

[0016]

[0017] Wherein, V tmin and V tmax are respectively the minimum and maximum operating values of the voltage at the output port of the mobile power generation vehicle.

[0018] Preferably, in step 3, the parameters are all determined by the empirical method.

[0019] Preferably, in step 4, the parameters are all determined by the empirical method.

[0020] Preferably, in step 5, the smooth switching compensation means adding a smooth switching compensation signal to the input link of the integral link of the PI adjustment module, so that the original input reactive power deviation signal is changed to the difference signal between the reactive power deviation signal and the smooth switching compensation signal, so as to smoothly convert the power control mode in the grid-connected mode to the voltage control mode in time when V t exceeds the limit.

[0021] Preferably, in step 5, the parameters are all determined by the empirical method.

[0022] Compared with the prior art, the beneficial effects of the present invention include:

[0023] 1. The present invention uses voltage deviation as the basis for judging the disconnection of the mobile power generation vehicle, with a simple principle, low time delay and easy to implement, avoiding problems such as slow switching speed and instability caused by large detection delay.

[0024] 2. The present invention adopts a tracking compensation method to compensate the voltage deviation signal into the PI module of the reactive power control, so that the control mode of the mobile power generation vehicle changes from constant power control to constant voltage control during the disconnection process, avoiding the switching of the control loop switch and making the operation mode switching smoother.

[0025] 3. The present invention introduces a transient response compensation signal into the outer-loop voltage control command of the excitation control system, so that a component of constant voltage control is directly introduced into the excitation control system at the first time of disconnection, avoiding the phenomenon of rapid voltage collapse caused by large disturbances and improving the stability of the operation mode switching. Description of the Drawings

[0026] Figure 1 is the smooth switching control block diagram of the mobile power generation vehicle in island operation in this specific embodiment. Specific Embodiment

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings, but it does not limit the protection scope of the present invention.

[0028] Referring to Figure 1 shown, the specific implementation steps of a smooth switching control method for an island operation of a mobile power generation vehicle are as follows:

[0029] Step 1: Subtract the output reactive power target value Q ref in the grid-connected operation mode of the mobile power generation vehicle from the output reactive power signal Q of the diesel generator measured by the internal measurement and control module of the mobile power generation vehicle to obtain a deviation value signal of reactive power;

[0030] Step 2: Subtract the output port voltage V t measured by the internal measurement and control module of the mobile power generation vehicle from the limited voltage V tL calculated by the voltage limiting calculation module to obtain a voltage deviation compensation signal.

[0031] The calculation formula of the voltage limiting calculation module is:

[0032]

[0033] In the formula, V tmin , V tmax are respectively the minimum and maximum operating values of the output port voltage of the mobile power generation vehicle.

[0034] Step 3: Connect the voltage deviation compensation signal to a PI adjustment module with parameters to form an original signal of the compensation branch, where the parameters are all determined by the empirical method.

[0035] Step 4: Define K C1 , K C2 as the static gain coefficient of smooth switching compensation and the static gain coefficient of transient response compensation respectively. Multiply the original signal of the compensation branch by K C1 , K C2 respectively to form a smooth switching compensation signal and a transient response compensation signal, where the parameters K C1 , K C2 are all determined by the empirical method.

[0036] Step 5: Connect the deviation value signal of reactive power to a PI adjustment module with parameters and compensated by smooth switching to form a primary voltage correction signal V qe . Among them, smooth switching compensation means adding a smooth switching compensation signal to the input link of the integral link of the PI adjustment module, so that the original input reactive power deviation signal is changed to the difference signal between the reactive power deviation signal and the smooth switching compensation signal, so as to tWhen an over-limit occurs, smoothly convert the power control mode in the grid-connected mode to the voltage control mode in a timely manner. The parameters are all determined by the empirical method.

[0037] Step 6: Perform a summation operation on the voltage correction signal V qe and the port voltage control target value V ref to calculate the port voltage control target value V refqe .

[0038] Step 7: Subtract the port voltage V refqe from the port voltage control target value V t after the first correction, and subtract the transient response compensation signal value to obtain the outer-loop voltage control command V AVR of the excitation control system.

[0039] Step 8: Output V AVR to the excitation control system to complete the smooth switching control of the mobile power generation vehicle in island operation.

Claims

1. A smooth switching control method for an island operation of a mobile power generation vehicle, Characterized in that: It includes the following steps: Step 1: Subtract the target value Q of the output reactive power in the grid-connected operation mode of the mobile power generation vehicle ref from the reactive power signal Q of the diesel generator output measured by the internal measurement and control module of the mobile power generation vehicle to obtain a deviation value signal of the reactive power; Step 2: Subtract the output port voltage V measured by the internal measurement and control module of the mobile power generation vehicle t from the limited voltage V calculated by the voltage limiting calculation module tL to obtain a voltage deviation compensation signal; Step 3: Connect the voltage deviation compensation signal to the PI adjustment module with the parameter of to form the original signal of the compensation branch; Step 4: Define K C1 and K C2 are the static gain coefficients for steady-state switching compensation and transient response compensation respectively. Multiply the original signal of the compensation branch by K C1 and K C2 respectively to form the steady-state switching compensation signal and the transient response compensation signal; Step 5: Connect the deviation value signal of the reactive power to a PI regulation module with smooth switching compensation and parameters of to form a primary voltage correction signal V qe ; Step 6: Sum the voltage correction signal V qe with the port voltage control target value V ref to calculate the port voltage control target value V refqe after the first correction; Step 7: Subtract the port voltage V refqe from the target value V of the port voltage after the first correction t , and the transient response compensation signal value to obtain the outer loop voltage control command V of the excitation control system AVR ; Step 8: Output V AVR to the excitation control system to complete the smooth switching control of the mobile power generation vehicle in island operation.

2. The smooth switching control method for an island operation of a mobile power generation vehicle according to claim 1, Characterized in that: In the step 2, the calculation formula of the voltage limit calculation module is: Where, V tmin and V tmax are respectively the minimum and maximum operating values of the output port voltage of the mobile power generation vehicle.

3. The smooth switching control method for an island operation of a mobile power generation vehicle according to claim 1, Characterized in that: In the said step 3, the parameters are all determined by the empirical method.

4. The smooth switching control method for an island operation of a mobile power generation vehicle according to claim 1, Characterized in that: In step 4, the parameters K C1 , K C2 are both determined by the empirical method.

5. The smooth switching control method for an island operation of a mobile power generation vehicle according to claim 1, Characterized in that: In the said step 5, the smooth switching compensation means adding a smooth switching compensation signal to the input link of the integral link of the PI adjustment module, so that the original input reactive power deviation signal is changed to the difference signal between the reactive power deviation signal and the smooth switching compensation signal, so as to t smoothly convert the power control mode in the grid-connected mode to the voltage control mode in time when 6. The smooth switching control method for an island operation of a mobile power generation vehicle according to claim 1, Characterized in that: In the said step 5, the parameters are all determined by the empirical method.

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