Dispatchable power supply system economic coordination strategy based on dynamic diffusion algorithm

Abstract

The invention discloses an economic coordination strategy of a schedulable power supply system based on a dynamic diffusion algorithm. The economic coordination strategy mainly comprises a micro-increasing cost calculation module, a communication module, a coordination control module and a voltage and current double-closed-loop control module. In the micro-increasing cost calculation module, the micro-increasing cost of different batteries is calculated for the fuel battery and the storage battery. In the communication module, a dynamic diffusion algorithm is utilized, only one communication variable is exchanged with adjacent communication nodes, and required average value information is obtained. In the cooperative control module, only one integrator is needed, while the direct current bus voltage is maintained to be close to a bus voltage reference value, the micro-increasing cost of each dispatchable power supply is consistent, so that the bus voltage recovery and the power generation cost are minimum. According to the invention, by designing a novel cooperative controller, the purposes of voltage regulation and economic coordination are completed based on the same time scale, so that stable recovery of bus voltage and optimal distribution of output power of the schedulable power supply system are realized.

Description

Technical Field

[0001] The present invention relates to the field of distributed energy storage systems for DC microgrids, and particularly to an economic coordination strategy for a dispatchable power system based on a dynamic diffusion algorithm. Background Art

[0002] Regarding the economic dispatch problem of the dispatchable power system, there is a difference in the time scales between the third-level economic coordination control layer and the second-level voltage recovery control layer, resulting in their inability to cooperate and optimize under the same time scale. This mismatch in time scales not only restricts the improvement of the operation efficiency of the dispatchable power system but also makes it difficult for each dispatchable power source to maintain the optimal operation state in real time, leading to problems such as voltage deviation and unreasonable power distribution in the dispatchable power system. To adjust and optimize the third-level economic coordination control layer and the second-level voltage recovery control layer of the dispatchable power system and solve the problem of inconsistent time scales of different control layers, the present invention designs an economic coordination strategy for the dispatchable power system based on a dynamic diffusion algorithm. By designing a new type of cooperative controller, the goals of voltage regulation and economic coordination are completed based on the same time scale to achieve the stable recovery of the bus voltage and the optimal distribution of output power of the dispatchable power system, ensuring the stability and economy of the system. In addition, the communication network of the present invention is constructed based on the multi-agent diffusion algorithm, and only one average virtual regulation factor needs to be transmitted between adjacent dispatchable power sources, effectively reducing the communication burden of the system. Summary of the Invention

[0003] To achieve the above object, the technical solution provided by the present invention is as follows:

[0004] Step S1: The dispatchable power sources in the dispatchable power system include fuel cells and storage batteries. At the starting point of each sampling period, the DC-side inductor current i Li and the DC-side output voltage u oi of each dispatchable power source are sampled respectively.

[0005] Step S2: In the incremental cost calculation module, the incremental cost represents the cost increase per unit output. The incremental cost λ i of the dispatchable power source is divided into the incremental cost λ fcsi of the fuel cell and the incremental cost λ bssi of the storage battery. For the fuel cell, multiply the DC-side output power P fcsi of the fuel cell by 2 times the fuel cell cost coefficient a fcsi , and then add the fuel cell increment coefficient b fcsi to obtain the incremental cost λ fcsi of the fuel cell. Its expression is:

[0006] λ fcsi = 2a fcsi Pfcsi +b fcsi (1)

[0007] For the storage battery, multiply the value obtained by subtracting the state of charge (SOC) of the storage battery from 1 by 6 times the maximum power P of charge and discharge of the storage battery bssi , and add 2 times the output power P of the DC side of the storage battery max,bssi . Multiply the obtained result by the cost coefficient a of the storage battery bssi , and then add the incremental coefficient b of the storage battery bssi to obtain the incremental cost λ of the storage battery bssi . Its expression is bssi :

[0008] λ bssi =a bssi [6P max,bssi (1 - SOC bssi ) + 2P bssi + b bssi (2)

[0009] Step S3: In the communication module, for each virtual regulation factor y of the dispatchable power sources collected, use the dynamic diffusion algorithm to obtain the average value y of the virtual regulation factors of the dispatchable power source system i ; i,avg

[0010] Step S4: In the coordinated control module, multiply the value obtained by subtracting the incremental cost λ of the dispatchable power source from the virtual incremental cost factor λ vm by the regulation coefficient θ, and then take the sine function of the result to obtain the virtual transition factor x i . Multiply the virtual transition factor x i by the DC side output voltage u i to obtain the virtual regulation factor y oi . Its expression is i :

[0011] y i =u oi ×sin[(λ vm -λ i )×θ] (3)

[0012] Divide the average value y of the virtual regulation factors by the virtual transition factor x i,avg to obtain the corrected voltage. Then subtract the corrected voltage from the bus reference voltage value u i , and pass it through an integration link to obtain the coordinated control voltage compensation amount Δu ref . The expression of the coordinated control voltage compensation amount Δu i is i :

[0013] ​

[0014] Step S5: In the voltage-current double closed-loop control module, add the bus voltage reference value u ref and the coordinated control voltage compensation Δu i , subtract the DC-side output voltage u oi from the sum, and then obtain the DC-side reference current through the voltage outer-loop PI controller G p (s). Subtract the DC-side inductor current i Li from the DC-side reference current, and then obtain the drive voltage through the current inner-loop PI controller G e (s). Compare the drive voltage with the triangular carrier wave to obtain the PWM modulation signal.

[0015] Furthermore, in Step S2, the value range of the fuel cell cost coefficient a fcsi is 0.1 < a fcsi < 1, the value range of the fuel cell increment coefficient b fcsi is 1 < b fcsi < 10, the value range of the battery cost coefficient a bssi is 0.1 < a bssi < 1, the value range of the battery increment coefficient b bssi is 1 < b bssii < 10; in Step S4, the value range of the adjustment coefficient θ is 0.1 < θ < 1.

[0016] Compared with the prior art, the principle and advantages of this solution are as follows:

[0017] The present invention discloses an economic coordination strategy for a dispatchable power supply system based on a dynamic diffusion algorithm, mainly including an incremental cost calculation module, a communication module, a coordinated control module, and a voltage-current double closed-loop control module. In the incremental cost calculation module, for fuel cells and batteries, calculate the incremental costs of different batteries. In the communication module, using the dynamic diffusion algorithm, only exchange a communication variable with adjacent communication nodes to obtain the required average value information. In the coordinated control module, only through an integrator, while maintaining the DC bus voltage near the bus voltage reference value, make the incremental costs of each dispatchable power supply consistent to meet the requirements of bus voltage recovery and minimum power generation cost. The present invention designs a new type of coordinated controller to achieve the goals of voltage regulation and economic coordination on the same time scale, so as to realize the stable recovery of the bus voltage and the optimal distribution of the output power of the dispatchable power supply system. Description of the Drawings

[0018] Figure 1 is the main circuit diagram of the dispatchable power supply system in the embodiment of the present invention;

[0019] Figure 2It is the control block diagram of the economic coordination strategy of the schedulable power supply system based on the dynamic diffusion algorithm in the embodiment of the present invention;

[0020] Figure 3 It is the waveform diagram of the bus voltage in the embodiment of the present invention;

[0021] Figure 4 It is the waveform diagram of the incremental cost in the embodiment of the present invention. Specific embodiments

[0022] The present invention will be further described below in conjunction with specific embodiments:

[0023] Figure 1 The shown is the main circuit diagram of the schedulable power supply system, which is composed of two fuel cells and two storage batteries connected in parallel through a DC-DC converter. Among them, i = 1, 2, 3, 4, u ref is the reference value of the bus voltage of the schedulable power supply system, i Li is the DC-side inductor current of each schedulable power supply, u oi is the DC-side output voltage of each schedulable power supply, i oi is the DC-side output current of each schedulable power supply, R loadi is the load resistance of each bus, R linei is the line impedance corresponding to each schedulable power supply. The line impedances of the four schedulable power supplies are 0.1Ω, 0.15Ω, 0.2Ω, and 0.25Ω respectively, R i is the line impedance corresponding to different schedulable power supplies. The line impedances between the four schedulable power supplies are 0.3Ω, 0.33Ω, 0.36Ω, and 0.4Ω respectively.

[0024] Figure 2 The shown is the control block diagram of the economic coordination strategy of the schedulable power supply system based on the dynamic diffusion algorithm, including the following steps:

[0025] Step S1: The schedulable power supplies in the schedulable power supply system include fuel cells and storage batteries. At the starting point of each sampling period, the DC-side inductor current i Li and the DC-side output voltage u oi of each schedulable power supply are sampled respectively;

[0026] Step S2: In the incremental cost calculation module, the incremental cost represents the cost increased per unit of output. The incremental cost λ i of the schedulable power supply is divided into the incremental cost λ fcsi of the fuel cell and the incremental cost λ bssi of the storage battery. For the fuel cell, multiply the DC-side output power P fcsi of the fuel cell by 2 times the fuel cell cost coefficient a fcsiThe result is added with the fuel cell increment factor b fcsi , we get the incremental cost of fuel cell λ fcsi , whose expression is:

[0027] λ fcsi =2a fcsi P fcsi +b fcsi (5)

[0028] For batteries, subtract the battery state of charge SOC from 1 bssi The value obtained is multiplied by 6 times the maximum power P of the battery charge and discharge max,bssi , plus 2 times the battery DC output power P bssi , multiply the result by the battery cost coefficient a bssi , plus the battery increment factor b bssi , we get the battery incremental cost λ bssi , whose expression is:

[0029] λ bssi =a bssi [6P max,bssi (1-SOC bssi )+2P bssi ]+b bssi (6)

[0030] Step S3: In the communication module, the collected virtual adjustment factors y of each dispatchable power source are i , the dynamic diffusion algorithm is used to obtain the average value y of the virtual regulation factor of the dispatchable power system i,avg ;

[0031] Step S4: In the collaborative control module, the virtual incremental cost factor λ vm Subtract the incremental cost of dispatchable power sources λ i The obtained value is multiplied by the adjustment coefficient θ, and then the result is taken as a sine function to obtain the virtual transition factor x i , the virtual transition factor x i Multiply by the DC side output voltage u oi Get the virtual adjustment factor y i , whose expression is:

[0032] y i =u oi ×sin[(λ vm -λ i )×θ] (7)

[0033] The virtual adjustment factor average value y i,avg Divide by the virtual transition factor x i Get the corrected voltage, and then use the bus reference voltage value uref Subtract the correction voltage, and obtain the coordinated control voltage compensation Δu through an integration link i , and the coordinated control voltage compensation Δu i has the following expression:

[0034]

[0035] Step S5: In the voltage-current double closed-loop control module, add the bus voltage reference value u ref and the coordinated control voltage compensation Δu i , then subtract the DC-side output voltage u oi . After that, obtain the DC-side reference current through the voltage outer-loop PI controller G p (s). Subtract it from the DC-side inductor current i Li , and then obtain the drive voltage through the current inner-loop PI controller G e (s). Compare the drive voltage with the triangular carrier wave to obtain the PWM modulation signal.

[0036] Furthermore, in step S2, the value range of the fuel cell cost coefficient a fcsi is 0.1 < a fcsi < 1, and the value range of the fuel cell increment coefficient b fcsi is 1 < b fcsi < 10. The value range of the battery cost coefficient a bssi is 0.1 < a bssi < 1, and the value range of the battery increment coefficient b bssi is 1 < b bssii < 10; in step S4, the value range of the adjustment coefficient θ is 0.1 < θ < 1.

[0037] Figure 3 The waveform diagram of the bus voltage of the dispatchable power supply system is shown. When the strategy implemented by the present invention is adopted, the bus voltage of the dispatchable power supply system can recover to around the bus voltage reference value of 400V at 0.1s, and the voltage drop percentage is less than 0.5%, indicating that this method can effectively achieve the recovery of the bus voltage of the dispatchable power supply system and ensure the stable operation of the system.

[0038] Figure 4 The waveform diagram of the incremental cost of each dispatchable power supply is shown. Adopting the strategy implemented by the present invention can promote the rapid convergence of the incremental costs of each dispatchable power supply. The incremental costs between fuel cells are almost the same at the beginning, and the incremental costs between batteries are also almost the same at the beginning. At 0.6s, the incremental costs of each dispatchable power supply are the same and remain at around 525 cents per watt, indicating that this method can effectively and quickly achieve the equal incremental cost operation of the dispatchable power supply system, minimize the power generation cost of the system, and ensure the economy of the system.

[0039] As can be seen from the above analysis, the present invention designs an economic coordination strategy for a dispatchable power supply system based on a dynamic diffusion algorithm. By designing a new type of cooperative controller, the goals of voltage regulation and economic coordination are completed on the same time scale to achieve the stable recovery of the bus voltage and the optimal distribution of output power of the dispatchable power supply system, ensuring the stability and economy of the system.

[0040] The above-described embodiments are only preferred embodiments of the present invention and do not limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. An economic coordination strategy for a schedulable power supply system based on a dynamic diffusion algorithm, characterized in that It includes the following steps: Step S1: The dispatchable power sources in the dispatchable power system include fuel cells and storage batteries. At the start point of each sampling period, sample the DC-side inductor current i Li and the DC-side output voltage u oi respectively; Step S2: In the incremental cost calculation module, the incremental cost represents the cost increase per unit of output. The incremental cost λ of the dispatchable power source i is divided into the incremental cost λ fcsi of the fuel cell and the incremental cost λ bssi of the storage battery. For the fuel cell, multiply the DC-side output power P fcsi of the fuel cell by 2 times the fuel cell cost coefficient a fcsi , and then add the fuel cell increment coefficient b fcsi to the obtained result to get the incremental cost λ fcsi of the fuel cell. Its expression is: λ fcsi = 2a fcsi P fcsi + b fcsi (1) For the storage battery, subtract the state of charge (SOC) of the storage battery from 1 bssi Multiply the obtained value by 6 times the maximum power P of charge and discharge of the storage battery max,bssi and add 2 times the output power P on the DC side of the storage battery bssi Multiply the obtained result by the cost coefficient a of the storage battery bssi and then add the incremental coefficient b of the storage battery bssi to obtain the incremental cost λ of the storage battery bssi The expression is as follows: λ bssi = a bssi [6P max,bssi (1 - SOC bssi ) + 2P bssi + b bssi (2) Step S3: In the communication module, for each virtual adjustment factor y of the dispatchable power sources collected, i , the average value y of the virtual adjustment factors of the dispatchable power source system is obtained by using the dynamic diffusion algorithm i,avg ; Step S4: In the coordinated control module, subtract the incremental cost λ vm of the dispatchable power source from the virtual incremental cost factor λ vm , multiply the obtained value by the regulation coefficient θ, then take the sine function of the result to obtain the virtual transition factor x i . Multiply the virtual transition factor x i by the DC-side output voltage u oi to obtain the virtual regulation factor y i . Its expression is as follows: vm from the virtual incremental cost factor λ vm i The obtained value is multiplied by the regulation coefficient θ, and then the sine function of the result is taken to obtain the virtual transition factor x i . i The virtual transition factor x i i is multiplied by the DC-side output voltage u oi oi to obtain the virtual regulation factor y i i as follows: y i = u oi × sin[(λ vm - λ i ) × θ] (3) Divide the average value y of the virtual adjustment factor i,avg by the virtual transition factor x i to obtain the corrected voltage, and then subtract the corrected voltage from the bus reference voltage value u ref and obtain the cooperative control voltage compensation Δu through an integration link i . The expression of the cooperative control voltage compensation Δu i is as follows: Step S5: In the voltage-current double closed-loop control module, add the bus voltage reference value u ref and the coordinated control voltage compensation amount Δu i , subtract the DC side output voltage u oi from the sum, and then obtain the DC side reference current through the voltage outer loop PI controller G p (s). Subtract the DC side inductor current i Li from the DC side reference current, and then obtain the driving voltage through the current inner loop PI controller G e (s). Compare the driving voltage with the triangular carrier wave to obtain the PWM modulation signal.

2. The economic coordination strategy of the schedulable power supply system based on the dynamic diffusion algorithm according to claim 1, characterized in that In step S2, the fuel cell cost coefficient a fcsi has a value range of 0.1 < a fcsi < 1, and the fuel cell incremental coefficient b fcsi has a value range of 1 < b fcsi < 10. The battery cost coefficient a bssi has a value range of 0.1 < a bssi < 1, and the battery incremental coefficient b bssi has a value range of 1 < b bssii < 10.

3. The economic coordination strategy of the schedulable power supply system based on the dynamic diffusion algorithm according to claim 1, characterized in that, In step S4, the value range of the adjustment coefficient θ is 0.1 < θ < 1.

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