Power-phase coordination control method and system for network-constructed diesel storage power supply system

Abstract

The application discloses a kind of network type diesel storage power supply system power-phase collaborative control method and system, including dynamic power correction and dynamic phase correction two components, dynamic power correction part is calculated power compensation item by load power and diesel generator reference power, real-time adjustment is carried out to energy storage unit reference power using power compensation item, so that energy storage unit quickly releases and absorbs load dynamic power, reduce diesel generator power fluctuation, realize diesel generator reverse power effective inhibition;Dynamic phase correction part is calculated phase compensation item by load power and angular frequency, real-time compensation is carried out to energy storage unit output phase using phase compensation item, realize system low-frequency power oscillation effective inhibition.The application realizes the collaborative inhibition of network type diesel storage power supply system reverse power and power oscillation under impact load, guarantees the safe and stable operation of system.

Description

Technical Field

[0001] This invention relates to the field of diesel-storage power supply system control technology, and in particular to a power-phase coordinated control method and system for a grid-type diesel-storage power supply system. Background Technology

[0002] In remote areas such as oilfield drilling platforms where the main power grid is difficult to cover, a diesel-storage parallel system consisting of an energy storage unit and a diesel generator is often used as the main power source to meet the peak-to-average power requirements during drilling. The energy storage unit uses virtual synchronous machine control to simulate the external characteristics of a synchronous generator. It and the diesel generator respond to load power changes together according to the ratio of their droop coefficients, and together they act as a voltage source to support the AC bus voltage. Compared to a single diesel generator power supply system, this scheme can significantly reduce the diesel generator configuration capacity and improve system efficiency and dynamic response capability. However, due to the significant differences in the output characteristics of the diesel generator and the energy storage converter, the system often experiences reverse power and power oscillation problems when facing load power surges.

[0003] When the load power suddenly drops from its peak to its trough, the diesel generator and energy storage unit will experience reverse overshoot during the dynamic process, which can easily lead to a large reverse power output from the diesel generator and energy storage unit. Since the diesel generator is difficult to absorb reverse power, it is easy to trigger the diesel generator reverse power protection and cause it to trip. At the same time, due to the large difference in the dynamic response characteristics of the diesel generator and energy storage unit, when both are operating as voltage sources, power oscillations are also prone to occur when the load power changes abruptly. Power oscillations can easily cause the energy storage converter to overload, seriously affecting the safe operation of the system.

[0004] For the suppression of reverse power and power oscillation in diesel-storage power supply systems, some studies have proposed solutions:

[0005] Patent application CN 119134389A discloses a method and system for suppressing power oscillations in a grid-type diesel-storage parallel system under oilfield impact loads. This method calculates the angular frequency compensation value by using the output power of the energy storage converter and the total load power, and adjusts the output angular frequency of the energy storage converter in real time to quickly track the angular frequency of the diesel generator, thus suppressing low-frequency power oscillations in the grid-type diesel-storage parallel system under oilfield impact loads. However, this method feeds the load power forward to the energy storage angular frequency, which can easily cause sudden changes in the energy storage angular frequency under oilfield impact loads, leading to system frequency instability. Simultaneously, the diesel generator output power fluctuates repeatedly with the impact load, making it impossible to maintain operation within the high-efficiency range to suppress reverse power from the diesel generator.

[0006] Invention patent application CN 120320362A discloses a method and system for suppressing power oscillations in a grid-type diesel-storage combined power supply system. This method introduces the instantaneous active power of the diesel generator and energy storage converter into an instantaneous power interleaved feedback compensation branch, calculates the power angle compensation amount, and adjusts the phase of the energy storage converter in real time to suppress power oscillations in the grid-type diesel-storage combined power supply system. However, this method only suppresses system power oscillations through phase compensation and does not directly solve the reverse power problem. Furthermore, it requires real-time acquisition of the active power of the diesel generator, but in practice, the output parameters of the diesel generator are difficult to measure quickly and accurately, which can easily introduce interference to the energy storage unit.

[0007] In summary, current research has failed to simultaneously address the issues of reverse power and power oscillation in diesel-storage power supply systems. Therefore, there is an urgent need for a control method that can effectively and synergistically suppress both reverse power and power oscillation in the system to avoid diesel generator reverse power protection and energy storage unit overload under impact loads, thereby ensuring the safe and stable operation of the system. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a power-phase coordinated control method and system for a grid-type diesel-storage power supply system, which addresses the shortcomings of the existing technology, and solves the problems of reverse power protection and power oscillation of diesel generators.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a power-phase coordinated control method for a grid-type diesel-storage power supply system, wherein the grid-type diesel-storage power supply system includes a diesel generator and at least one energy storage unit, and both the diesel generator and the energy storage unit are connected to an AC bus, comprising the following steps:

[0010] Sample the three-phase output voltage and three-phase output current of the energy storage unit, and calculate the output active power P of the energy storage unit. i and output reactive power Q i Sample the three-phase voltage and three-phase current on the load side, and calculate the instantaneous power P of the load. L ;

[0011] Utilizing the instantaneous power P of the load L The rated power P of the diesel generator ndg Given the preset load factor α and the number of parallel energy storage units n, calculate the power correction term P. ref_di ;

[0012] The basic reference value P of the active power of the superimposed energy storage unit ref_fi With the power correction term P ref_di The active power command value P of the energy storage unit is obtained. refi :

[0013] Utilizing the energy storage unit to output angular frequency ω iCalculate the first compensated phase Δθ di1 ; Utilizing the instantaneous power P of the load L Calculate the second compensated phase Δθ di2 ;

[0014] Using the active power command value P of the energy storage unit refi Instantaneous active power P i Rated output voltage angular frequency ω0, first compensated phase Δθ di1 Second compensation phase Δθ di2 The final phase command θ of the energy storage unit's output voltage is calculated. refi :

[0015] Using the reactive power reference value Q of the energy storage unit refi Instantaneous reactive power Q i And the rated output voltage amplitude E0, and the command to calculate the output voltage amplitude of the energy storage unit E. refi ;

[0016] According to the energy storage unit output voltage amplitude command E refi and the final phase command θ of the output voltage refi It generates a PWM modulation signal to drive the switching transistors of the energy storage unit.

[0017] This invention achieves effective suppression of both reverse power and power oscillations through the synergy of dynamic power correction and dynamic phase correction. Furthermore, this invention eliminates the need to collect diesel generator output parameters or compensate for the angular frequency of the energy storage converter, thus solving the problems of interference in diesel generator parameter measurement and system frequency instability in existing technologies.

[0018] The preset load factor α ranges from 0.6 to 0.8.

[0019] The power correction term P ref_di The calculation formula is: .

[0020] The energy storage unit outputs a voltage amplitude command E. refi The calculation formula is: ; where D qi This is the reactive power droop coefficient.

[0021] The output angular frequency ω of the energy storage unit i The calculation formula is: ; among which, J i and D pi These are the virtual inertia of energy storage and the damping coefficient, respectively.

[0022] In this invention, the first compensation phase Δθ di1 The calculation formula is Second compensation phase Δθ di2 The calculation formula is ;in, , k c1 and k c2 These are the frequency feedforward correction coefficient and the power feedforward correction control coefficient, respectively, where s is the complex frequency and D is the power feedforward correction control coefficient. pi is the damping coefficient.

[0023] Energy storage unit output voltage final phase command θ refi The calculation formula is: .

[0024] As an inventive concept, the present invention also provides a power-phase coordinated control system for a grid-type diesel-storage power supply system, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the steps of the above method.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) By introducing a power correction term, the present invention enables the energy storage unit to actively release power during drilling to support the peak load power; and to quickly absorb reverse power in drilling mode to raise the output power of the diesel generator to the high-efficiency output range, thereby keeping the output power of the diesel generator basically constant and avoiding the power from dropping to a negative value. This effectively solves the problem of reverse power protection tripping of the diesel generator and improves the fuel efficiency of the diesel generator.

[0027] (2) By introducing a phase correction term, the present invention directly compensates the phase of the energy storage unit by using frequency feedforward and load power feedforward, which can quickly eliminate low-frequency power oscillations caused by impact load and power correction term.

[0028] (3) The calculation of power correction and phase correction in this invention only includes algebraic operations and first-order low-pass operations. The calculation formula has a low transfer function order, which is easy to implement with a discrete controller. Phase correction is achieved through frequency feedforward and power feedforward, which will not affect the inertial response characteristics of the energy storage unit. Power feedforward correction is achieved through first-order low-pass calculation, which can effectively avoid introducing sampling process noise into the control loop of the energy storage converter.

[0029] (4) The present invention can effectively suppress the reverse power and power oscillation of the system simultaneously through power-phase coordinated control, so as to ensure the safe and stable operation of the system under the impact load of the oil field. Attached Figure Description

[0030] Figure 1 This is a structural diagram of a grid-type diesel-storage power supply system in an embodiment of the present invention;

[0031] Figure 2This is a schematic diagram of the power-phase coordinated control method in an embodiment of the present invention;

[0032] Figure 3 These are the simulation waveforms of inverse power and power oscillation when using conventional control methods in this embodiment of the invention;

[0033] Figure 4 The inverse power and power oscillation waveforms are shown in the embodiments of the present invention after employing the power-phase coordinated control method. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, the grid-type diesel-storage power supply system of this embodiment includes a diesel generator and at least one energy storage unit. Both the diesel generator and the energy storage unit are connected to the same AC bus via output impedance. The load includes the impact load during the tripping process and the steady-state load during drilling. In the figure, X... dg X is the output impedance of the diesel generator. i Let be the output impedance of the i-th energy storage unit, and SW1 and SW2 be load switches.

[0037] like Figure 2 As shown, the power-phase coordinated control method for a grid-type diesel-storage power supply system according to an embodiment of the present invention includes the following steps:

[0038] Step 1: Sampling and Power Calculation; Sample the three-phase output voltage and three-phase output current of the energy storage unit, and calculate the output active power P of the energy storage unit. i and output reactive power Q i Sample the three-phase voltage and three-phase current on the load side, and calculate the instantaneous power P of the load. L ;

[0039] Step 2: Calculate the power correction term; using the instantaneous load power P L The rated power P of the diesel generator ndg Calculate the power correction term P based on the preset load factor α and the number of parallel energy storage units n. ref_di ;

[0040] Step 3: Calculate the active power command of the energy storage unit; use the basic reference value P of the active power of the energy storage unit. ref_fi (In this embodiment, the active power baseline reference value can be set to 0) and the power correction term P ref_di The active power command value P of the energy storage unit is obtained. refi : ;

[0041] Step 4: Calculate the phase correction term; output the energy storage unit's angular frequency ω i Introduce a frequency feedforward correction branch and calculate the compensated phase Δθ. di1 ; the load power P L Introduce a power feedforward correction branch and calculate the compensated phase Δθ. di2 ;

[0042] Step 5: Calculate the phase command output by the energy storage unit; utilize the active power command value P of the energy storage unit. refi With instantaneous active power P i and the rated output voltage angular frequency ω0, and the phase correction term Δθ di1 and Δθ di2 The final phase command θ of the energy storage unit output voltage is obtained. refi : ;

[0043] Among them, J i and D pi These represent the virtual inertia of energy storage and the damping coefficient, ω. i The output angular frequency of the energy storage unit.

[0044] Step 6: Calculate the output voltage amplitude command of the energy storage unit; use the reactive power reference value Q of the energy storage unit. refi With instantaneous reactive power Q i And the rated output voltage amplitude E0, and the command to calculate the output voltage amplitude of the energy storage unit E. refi ;

[0045] Step 7: PWM modulation; based on the output voltage amplitude E refi and phase command θ refi It generates a PWM modulation signal to drive the output of the energy storage converter.

[0046] In this embodiment, the power correction term P ref_di The calculation formula is: In tripping mode, the power correction term is positive, causing the energy storage unit to discharge rapidly and share the peak power. In drilling mode, the power correction term is negative, causing the active power command of the energy storage unit to shift towards charging, thereby quickly absorbing reverse power to maintain the diesel generator's output power within the high-efficiency output range (P). ndg(Nearby), to avoid power dropping to zero or a negative value.

[0047] In this embodiment, the first compensation phase Δθ di1 The calculation formula is Second compensation phase Δθ di2 The calculation formula is The transfer function of the frequency feedforward correction branch is: The transfer function of the power feedforward correction branch is: By introducing frequency feedforward and load power feedforward to compensate the phase of the energy storage unit, the power oscillation caused by the combined effect of impact load and power correction term can be effectively suppressed, thereby achieving coordinated suppression of system reverse power and power oscillation.

[0048] The embodiments of the present invention will be further illustrated below through specific experiments:

[0049] Figure 3 Simulation waveforms of inverse power and power oscillation under the conventional grid-connected synchronous control method are presented: When the load power suddenly drops from 12kW to 1kW, the diesel generator output power experiences a momentary reverse overshoot to -2.2kW, resulting in inverse power generation by the diesel generator; when the load power changes abruptly, the system also exhibits significant power oscillation during the transient process, with an amplitude of 4kW. For comparison, Figure 4 The reverse power and power oscillation waveforms of the grid-type diesel-storage power supply system using the power-phase coordinated control method of this invention are presented. When the load power suddenly drops, the diesel generator output power remains around 6kW, the power fluctuation is significantly reduced, and the lowest value is 4.4kW, with no reverse power occurring. At the same time, the system power oscillation amplitude is reduced to 1.8kW during the transient process, and the oscillation can decay rapidly, allowing the system to quickly enter a steady state, effectively suppressing power oscillation.

[0050] The above results show that the power-phase coordinated control method of this embodiment can reduce the power fluctuation of the diesel generator, maintain the output power of the diesel generator near the reference value, effectively suppress the reverse power problem of the diesel generator under impact load, and at the same time significantly reduce the amplitude and adjustment time of system power oscillation, thus achieving effective coordinated suppression of reverse power and power oscillation.

[0051] Example 2

[0052] Embodiment 2 of the present invention provides a control system corresponding to Embodiment 1 above, including a memory, a processor and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method of Embodiment 1 above.

[0053] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0054] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0055] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0056] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A power-phase coordinated control method for a grid-type diesel-storage power supply system, the grid-type diesel-storage power supply system comprising a diesel generator and at least one energy storage unit, wherein both the diesel generator and the energy storage unit are connected to an AC bus, characterized in that, Includes the following steps: Sample the three-phase output voltage and three-phase output current of the energy storage unit, and calculate the output active power P of the energy storage unit. i and output reactive power Q i Sample the three-phase voltage and three-phase current on the load side, and calculate the instantaneous power P of the load. L ; Utilizing the instantaneous power P of the load L The rated power P of the diesel generator ndg Given the preset load factor α and the number of parallel energy storage units n, calculate the power correction term P. ref_di ; The basic reference value P of the active power of the superimposed energy storage unit ref_fi With the power correction term P ref_di The active power command value P of the energy storage unit is obtained. refi : Utilizing the energy storage unit to output angular frequency ω i Calculate the first compensated phase Δθ di1 ; Utilizing the instantaneous power P of the load L Calculate the second compensated phase Δθ di2 ; Using the active power command value P of the energy storage unit refi Instantaneous active power P i Rated output voltage angular frequency ω0, first compensated phase Δθ di1 Second compensation phase Δθ di2 The final phase command θ of the energy storage unit's output voltage is calculated. refi : Using the reactive power reference value Q of the energy storage unit refi Instantaneous reactive power Q i And the rated output voltage amplitude E0, and the command to calculate the output voltage amplitude of the energy storage unit E. refi ; According to the energy storage unit output voltage amplitude command E refi and the final phase command θ of the output voltage refi It generates a PWM modulation signal to drive the switching transistors of the energy storage unit.

2. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to claim 1, characterized in that, The preset load factor α ranges from 0.6 to 0.

8.

3. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to claim 1, characterized in that, The power correction term P ref_di The calculation formula is: .

4. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to claim 1, characterized in that, The energy storage unit outputs a voltage amplitude command E. refi The calculation formula is: ; where D qi This is the reactive power droop coefficient.

5. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to claim 1, characterized in that, The output angular frequency ω of the energy storage unit i The calculation formula is: ; among which, J i and D pi These are the virtual inertia of energy storage and the damping coefficient, respectively.

6. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to claim 1, characterized in that, First compensation phase Δθ di1 The calculation formula is Second compensation phase Δθ di2 The calculation formula is ;in, , k c1 and k c2 These are the frequency feedforward correction coefficient and the power feedforward correction control coefficient, respectively, where s is the complex frequency and D is the power feedforward correction control coefficient. pi is the damping coefficient.

7. The power-phase coordinated control method for a grid-type diesel-storage power supply system according to any one of claims 1 to 6, characterized in that, Energy storage unit output voltage final phase command θ refi The calculation formula is: .

8. A power-phase coordinated control system for a grid-type diesel-storage power supply system, comprising a memory, a processor, and a computer program stored in the memory; characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

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