Inertia damping self-optimization-approaching setting method for diesel-storage hybrid power station oriented to pulse load

Abstract

The invention relates to a diesel-storage hybrid power station inertia damping self-optimization-approaching setting method for a pulse load, and the method comprises the steps: constructing a diesel-storage hybrid power station model which comprises a diesel generator, an energy storage system and the pulse load; the energy storage system adopts a rotor swing equation to simulate inertia and damping characteristics of the diesel generator and reflects the difference between the output power of the diesel generator and the output power of the energy storage converter through normalized oscillation power; in the self-optimal-approaching setting stage, the initial value of the angular velocity difference under the unit step is obtained through setting of the initial value theorem so as to decouple the inertia parameter and the damping parameter in the oscillation power, the inertia parameter is set, and then the final value of the oscillation power under the unit step is obtained through setting of the final value theorem so as to decouple the inertia parameter and the damping parameter in the oscillation power. And a damping parameter is set. According to the method, automatic matching of the VSG parameters can be realized under the condition that the inertia and damping of the SG are unknown, so that the SG-VSG power synchronism of the diesel-storage hybrid power station of the ship power system is improved, and continuous power deviation and even instability caused by mismatching of the inertia parameter and the damping parameter of the SG-VSG are inhibited.

Description

Technical Field

[0001] The invention relates to a technology in the field of hybrid power station control, in particular to a self-optimizing setting method for inertia damping of a diesel-storage hybrid power station facing pulse loads. Background Art

[0002] Under pulse load, the use of virtual synchronous generator (VSG) control in energy storage leads to continuous oscillation of the dynamic output power of the diesel power plant, aggravating the power asynchronism between VSG and synchronous generator (SG), and even system instability. The mismatch between the inertia and damping parameters of VSG and SG is the main reason for the above problems. However, due to confidentiality reasons, the inertia and damping parameters of the ship power plant SG may not be obtained, and the parameters may also shift due to equipment aging, making it difficult to adapt the VSG parameters according to the SG parameters. Summary of the invention

[0003] In view of the fact that the prior art does not consider the continuous disturbance of the pulse load to the system and the power oscillation phenomenon of the synchronous generator when the inertia and damping are unknown, and the power asynchronism between the VSG and SG and the system instability caused by the pulse load in the single load mutation scenario, the present invention proposes a self-optimizing setting method for inertia damping of a diesel-storage hybrid power station for pulse loads, which can realize automatic matching of VSG parameters when the SG inertia and damping are unknown, thereby improving the SG-VSG power synchronization of the diesel-storage hybrid power station of the ship power system and reducing the continuous power deviation or even instability caused by the mismatch between the SG-VSG inertia parameters and damping parameters.

[0004] The present invention is achieved through the following technical solutions:

[0005] The invention relates to a self-optimizing tuning method for inertia damping of a diesel-storage hybrid power station facing pulse loads. After constructing a diesel-storage hybrid power station model including a diesel generator, an energy storage system and a pulse load, the energy storage system uses a rotor swing equation to simulate the inertia and damping characteristics of the diesel generator and reflects the difference between the output power of the diesel generator and the energy storage converter through normalized oscillation power; in the self-optimizing tuning stage, the initial value theorem is used to tune the initial value of the angular velocity difference under a unit step to decouple the inertia parameter and the damping parameter in the oscillation power, and the inertia parameter is tuned, and then the final value theorem is used to tune the final value of the oscillation power under a unit step to decouple the inertia parameter and the damping parameter in the oscillation power, and the damping parameter is tuned.

[0006] The present invention relates to a system for implementing the above method, comprising: an SG measurement unit, a VSG measurement unit, a load measurement unit, a determination unit and a parameter setting unit, wherein: the SG measurement unit, the VSG measurement unit and the load measurement unit perform data acquisition processing according to system operation information, determine the load measurement unit information, perform load state determination processing, and obtain a result of whether parameter setting is started; the parameter setting unit performs parameter setting processing according to the SG measurement unit, the VSG measurement unit and the start-up determination information to obtain a parameter setting result. Technical Effects

[0007] The present invention realizes the decoupling of inertia parameter and damping parameter setting and the automatic adjustment of VSG control parameters to adapt SG characteristics through the initial value theorem and final value theorem of the frequency domain model, thereby smoothing the problem of diesel storage power oscillation under pulse load. The problem of power oscillation and even instability is solved from the root by matching VSG parameters with SG, and a targeted VSG parameter setting strategy is proposed in combination with the pulse load characteristics. Compared with the traditional method of manual trial and error adjustment when the SG inertia and damping parameters are unknown, the present invention realizes the automatic matching of VSG inertia parameters and damping parameters to SG, and achieves the active optimization of VSG parameters: after completing the parameter setting, there is no need to add other control systems, which greatly saves setting resources. Compared with the solution with the help of additional control, it has a once-and-for-all effect, and the present invention can eliminate power oscillation from the root, has better effect, and solves the problem that most of the existing technologies are aimed at single load mutation conditions and do not fully consider the continuous disturbance brought to the system by pulse loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a schematic diagram of a diesel storage system under pulse load;

[0009] Figure 2 It is a schematic diagram of pulse load power waveform;

[0010] Figure 3 It is the control flow chart of inertia parameter adaptive tuning;

[0011] Figure 4 Schematic diagram of VSG and SG output power;

[0012] Figure 5 Schematic diagram of VSG-SG oscillation power;

[0013] Figure 6 This is a schematic diagram of the VSG inertia parameter setting value;

[0014] Figure 7 Schematic diagram of VSG and SG output power;

[0015] Figure 8 Schematic diagram of VSG-SG oscillation power;

[0016] Fig. 9 Schematic diagram of VSG damping parameter setting values. DETAILED DESCRIPTION

[0017] This embodiment relates to a method for self-optimizing inertia damping of a diesel-storage hybrid power station for pulse loads, comprising:

[0018] Step 1: Construct Figure 1 The diesel-storage hybrid power plant model shown includes a diesel generator, an energy storage system and a pulse load.

[0019] The diesel generator comprises: a diesel engine, a synchronous generator (SG) and its control system. Due to different combinations of units in the system during operation, the inertia parameters and damping parameters obtained by the diesel generator set aggregation are unknown.

[0020] The energy storage system comprises: an energy storage battery, a DC-AC converter and a control system thereof, wherein: the energy storage converter adopts VSG grid-type control and supplies power synchronously with the diesel generator set.

[0021] like Figure 1 As shown, u1 and u2 represent the output voltages of VSG and SG respectively. i1 and i2 represent the output currents of VSG and SG respectively. SW1 and SW2 are the parallel switches of the energy storage converter and diesel generator respectively. line1 and Z line2 are the line impedances of VSG and SG respectively. m1 is the input torque of the synchronous generator, U dc is the DC side voltage of the DC-AC converter.

[0022] like Figure 2 As shown in the figure, it is the power waveform of the pulse load represented by the electronic radar. In the figure, T1 is the pulse on time, T2 is the pulse off time, T is the pulse period, and the period of the pulse load is generally greater than 100ms. The average power P av =P p d+P s (1-d), dynamic power Where: P p is the peak power of the pulse load, P s is the steady-state power, d is the duty cycle of the pulse power, P d is the dynamic power P L2 The peak value of the pulse load. The frequency domain equation is: ΔP load (s) = P d (1-e -sdT ) / [s(1-e -sT )].

[0023] Step 2: Based on the diesel-storage hybrid power plant model constructed in step 1, VSG parameters are optimized, including:

[0024] Step 2.1 Energy storage simulates the inertia and damping characteristics of the diesel generator through the rotor swing equation, specifically: Among them: variables related to the energy storage converter are represented by the subscript "1", and variables related to the diesel generator are represented by the subscript "2". n1 and P n2 are the rated power of energy storage converter and diesel generator respectively, P e1 and P e2 are the electromagnetic power output by the energy storage converter and the diesel generator, ω n is the rated angular frequency of the system, ω1 and ω2 are the virtual angular frequency of the energy storage converter and the rotor speed of the diesel generator, J1 and J2 are the inertia parameters of the energy storage converter and the diesel generator, D p1 and D p2 are the damping parameters of the energy storage converter and diesel generator respectively. The rated power of the diesel generator is P n2 , output reactance X f2 The parameters can be set according to the equipment nameplate. Therefore, the rated power P of the energy storage converter n1 , output reactance X f1 It can be configured according to the diesel generator parameter ratio: P n1 / P n2 =X f1 / X f2 =m.

[0025] Step 2.2: Obtain the system oscillation power and angular acceleration difference transfer function through the VSG-SG small signal model: By oscillation power ΔP 12 Reflects the difference in output power between the diesel generator and the energy storage converter: ΔP 12 =P e1 / m1-P e2 / m2, where: m1 and m2 are the reference powers of VSG and SG respectively, which are set in proportion to the rated power of the energy storage converter and the diesel generator; the electromagnetic power P of the energy storage converter and the diesel generator e1 and P e2 Equal to the line transmission power, k1 / m1=k2 / m2=k. The angular acceleration difference Δa is obtained 12 The transfer function for load changes is: Among them: α0~α3 expression is: Oscillation power ΔP 12 for:

[0026] Step 2.3 VSG inertia parameter optimization setting, in order to achieve the decoupling of inertia parameter and damping parameter in oscillation power, the initial value theorem is used to calculate the initial value of angular velocity difference under unit step, specifically: Since there is no ideal instantaneous sudden increase / decrease in load during the actual operation of the system, the load generally reaches a steady state after a relatively fast climbing process. Therefore, the first peak value of the angular acceleration difference appears after the load power has completed the climb, which can be approximately regarded as the initial value of the angular acceleration difference. And the ideal instantaneous sudden increase / decrease in load is the worst case, so the theoretical angular acceleration difference is always greater than the initial value of the angular acceleration difference actually measured. Assume that the initial value of the angular acceleration difference during the actual operation of the system is Δa 12s , and the VSG inertia parameter is known to be J1, then based on Δa 12s And the above formula, the SG inertia parameters are obtained by adjustment Set the VSG inertia parameter setting value J1 = m1J2 * / m2, the VSG inertia parameter can be continuously approached to the SG inertia parameter, which can reduce the angular acceleration difference and thus reduce the power oscillation. When the controller detects the rising edge of the pulse power, the VSG inertia parameter J1 is adjusted once, and the adjustment is repeated until the oscillation power is eliminated. The inertia parameter adaptive adjustment control process is as follows: Figure 3 shown.

[0027] Step 2.4 VSG damping parameter optimization setting: In order to achieve the decoupling of inertia parameters and damping parameters in the oscillation power, the final value theorem is used to calculate the final value of the oscillation power under unit step, specifically: The average oscillation power within a pulse load cycle is specifically: The VSG damping parameter is known to be D p1 , get the SG damping parameter D p2 * : Set the VSG damping parameter setting value D p1 =D p2 * , the VSG damping parameter can be adjusted to the SG inertia parameter to reduce the oscillation power. When the controller detects the rising edge of the pulse power, the VSG inertia parameter D p1 Perform a tuning once and repeat the tuning until the oscillating power is eliminated.

[0028] After specific actual experiments, an experimental platform for diesel-storage hybrid power station was built, which consists of a diesel generator, an energy storage converter, a pulse load and a conventional load. The specific parameters are as follows: the system rated frequency is 50Hz, the conventional load is 40kW. The pulse load parameters are shown in Table 1. The pulse load period T = 500ms, the duty cycle d = 0.5, the peak power P d=20kW. The parameters of the energy storage converter (VSG) are shown in Tables 2 and 3. The rated capacity P n1 =20kW, base capacity m1 = 20kW, line impedance X f1 =0.471Ω, scenario 1 inertia parameter J1 = 2kg·m2, damping parameter D p1 =20.28W / s, scenario 2 inertia parameter J1=1kg·m2, damping parameter D p1 =40.56W / s. Diesel generator (SG) parameters are shown in Tables 2 and 3. Rated capacity P n2 =20kW, base capacity m2 =20kW, line impedance X f2 =0.471Ω, inertia parameter J2 = 1kg·m2, damping parameter D p2 =20.28W / s.

[0029] Table 1 Parameters of pulse load

[0030] Scenario 1: Inertia parameter tuning

[0031] In order to verify the effectiveness of the inertia parameter tuning method, the parameters of the energy storage converter and diesel generator are set on the experimental platform of the diesel-storage hybrid power station as shown in Table 2.

[0032] Table 2 Parameters of diesel-storage hybrid power station

[0033] The specific simulation results and analysis are as follows: Based on the parameter setting method, the output power and oscillation power of VSG and SG are as follows: Figure 4 and Figure 5 As shown. At 1s, the pulse load is put into use. At this time, due to the serious mismatch between the inertia parameters of VSG and SG, the transient power imbalance between VSG and SG is also obvious, and the maximum oscillation power reaches 27.5%. Subsequently, the method in this paper begins to optimize the inertia parameters of VSG. The specific process is as follows Figure 8 As shown in the figure, it can be seen that the VSG inertia parameter gradually approaches the SG inertia parameter 1kg·m 2 , the parameter setting is basically completed in 4s (about 5 to 6 pulse cycles). At this time, the output power between VSG and SG is synchronized, and the oscillation power is less than 1%.

[0034] Scenario 2: Damping parameter tuning

[0035] In order to verify the effectiveness of the damping parameter tuning method, the parameters of the energy storage converter and diesel generator are set on the experimental platform of the diesel-storage hybrid power station as shown in Table 3.

[0036] Table 3 Parameters of diesel-storage hybrid power station

[0037] The specific simulation results and analysis are as follows: Based on the parameter setting method in this chapter, the output power and oscillation power of VSG and SG are respectively as follows: Figure 7 and Figure 8 As shown in the figure. At 1s, the pulse load is put into use. At this time, due to the serious mismatch between the damping parameters of VSG and SG, there is an uneven distribution problem between VSG and SG, and the maximum oscillation power reaches 43.2%. Subsequently, the method in this paper begins to adjust the VSG damping parameters. The specific process is as follows Fig. 9 As shown in the figure, it can be seen that the VSG inertia parameters gradually approach the SG inertia parameters 20.28W·s, and the parameter setting is basically completed in 2s (about 1 to 2 pulse cycles).

[0038] Compared with the prior art, this method greatly improves the power synchronization rate through the automatic parameter adjustment link based on the initial value of the SG-VSG angular acceleration and the average oscillation power. After adopting the prior art, the oscillation power will be reduced to 7-11%. After adopting this method, the oscillation power will be reduced to less than 1%.

[0039] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A self-optimizing method for inertia damping of a diesel-storage hybrid power station for pulse loads, characterized in that: After constructing a diesel-storage hybrid power station model including a diesel generator, an energy storage system and a pulse load, the energy storage system uses the rotor swing equation to simulate the inertia and damping characteristics of the diesel generator and reflects the difference in output power between the diesel generator and the energy storage converter through the normalized oscillation power; in the self-optimizing tuning stage, the initial value theorem is first used to obtain the initial value of the angular velocity difference under unit step to decouple the inertia parameter and the damping parameter in the oscillation power, and the inertia parameter is tuned, and then the final value theorem is used to obtain the final value of the oscillation power under unit step to decouple the inertia parameter and the damping parameter in the oscillation power, and the damping parameter is tuned.

2. The inertia damping self-optimization setting method for a diesel-storage hybrid power station for pulse loads according to claim 1 is characterized in that: The diesel-storage hybrid power plant model includes a diesel generator, an energy storage system and a pulse load, wherein: The diesel generator includes: a diesel engine, a synchronous generator (SG) and its control system. Due to different unit combinations in the system during operation, the inertia parameters and damping parameters obtained by the diesel generator set aggregation are unknown; The energy storage system includes: energy storage batteries, DC-AC converters and control systems thereof, wherein: the energy storage converters adopt VSG grid-type control and are synchronously powered with the diesel generator set; The average power P of the pulse load av =P p d+P s (1-d), dynamic power Where: P p is the peak power of the pulse load, P s is the steady-state power, d is the duty cycle of the pulse power, P d is the dynamic power P L2 The peak value of the pulse load frequency domain equation is: ΔP load (s) = P d (1-e -sdT ) / [s(1-e -sT )], T is the pulse period.

3. The inertia damping self-optimization setting method for a diesel-storage hybrid power station for pulse loads according to claim 1 is characterized in that: The rotor swing equation is used to simulate the inertia and damping characteristics of the diesel generator and the normalized oscillation power is used to reflect the difference between the output power of the diesel generator and the energy storage converter, which is specifically obtained by the following method: 1) Simulate the inertia and damping characteristics of the diesel generator through the rotor swing equation: Among them: variables related to the energy storage converter are represented by subscript "1", variables related to the diesel generator are represented by subscript "2", n1 and P n2 are the rated power of energy storage converter and diesel generator respectively, P e1 and P e2 are the electromagnetic power output by the energy storage converter and the diesel generator, ω n is the rated angular frequency of the system, ω1 and ω2 are the virtual angular frequency of the energy storage converter and the rotor speed of the diesel generator, J1 and J2 are the inertia parameters of the energy storage converter and the diesel generator, D p1 and D p2 are the damping parameters of the energy storage converter and diesel generator respectively, and the rated power of the diesel generator P n2 , output reactance X f2 The parameters can be set according to the equipment nameplate. Therefore, the rated power P of the energy storage converter is n1 , output reactance X f1 It can be configured according to the diesel generator parameter ratio: P n1 / P n2 =X f1 / X f2 =m; 2) The system oscillation power and angular acceleration difference transfer function are obtained through the VSG-SG small signal model: 12 Reflects the difference in output power between the diesel generator and the energy storage converter: ΔP 12 =P e1 / m1-P e2 / m2, where: m1 and m2 are the reference powers of VSG and SG respectively, which are set in proportion to the rated power of the energy storage converter and the diesel generator; the electromagnetic power P of the energy storage converter and the diesel generator e1 and P e2 Equal to the line transmission power, k1 / m1=k2 / m2=k, and the angular acceleration difference Δa is obtained 12 The transfer function for load changes is: Among them: α0~α3 expression is: Oscillation power ΔP 12 for:

4. The inertia damping self-optimization setting method for a diesel-storage hybrid power station for pulse loads according to claim 3 is characterized in that: The self-optimizing tuning stage specifically includes: a) Using the initial value theorem, find the initial value of the angular velocity difference under the unit step, specifically: Since there is no ideal instantaneous sudden increase / decrease in load during the actual operation of the system, the load generally reaches a steady state after a relatively fast climbing process. Therefore, the first peak value of the angular acceleration difference appears after the load power has completed the climb, which is approximately regarded as the initial value of the angular acceleration difference. The ideal instantaneous sudden increase / decrease in load is the worst case, so the theoretical angular acceleration difference is always greater than the actual measured initial value of the angular acceleration difference. Assuming that the initial value of the angular acceleration difference during the actual operation of the system is Δa 12s , and the VSG inertia parameter is known to be J1, then based on Δa 12s And the above formula, the SG inertia parameters are obtained by adjustment Set the VSG inertia parameter setting value J1 = m1J2 * / m2, so that the VSG inertia parameter is constantly approaching the SG inertia parameter, reducing the angular acceleration difference and thus reducing the power oscillation. When the controller detects the rising edge of the pulse power, the VSG inertia parameter J1 is adjusted once, and the adjustment is repeated until the oscillation power is eliminated; b) Using the final value theorem, find the final value of the oscillation power under unit step, specifically: The average oscillation power within a pulse load cycle is specifically: The VSG damping parameter is known to be D p1 , get the SG damping parameter D p2 * : Set the VSG damping parameter setting value D p1 =D p2 * , set the VSG damping parameter to the SG inertia parameter to reduce the oscillation power. When the controller detects the rising edge of the pulse power, adjust the VSG inertia parameter D p1 Perform a tuning once and repeat the tuning until the oscillating power is eliminated.

5. A self-optimizing system for inertia damping of a diesel-storage hybrid power station for pulse loads that implements the method described in any one of claims 1 to 4, characterized in that: include: SG measuring unit, VSG measuring unit, load measuring unit, judgment unit and parameter setting unit, wherein: the SG measuring unit, VSG measuring unit and load measuring unit perform data acquisition processing according to system operation information, judge the load measuring unit information, perform load state judgment processing, and obtain the result of whether parameter setting is started; the parameter setting unit performs parameter setting processing according to the SG measuring unit, VSG measuring unit and start judgment information to obtain the parameter setting result.

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