Hybrid power flow controller and control method and device thereof
By adopting a control strategy in which the converter first performs full-load regulation and then the phase-shifting transformer performs supplementary regulation, the problem of insufficient converter regulation capacity in the hybrid power flow controller is solved, and adaptive regulation and precise power flow control are achieved.
Patent Information
- Application Number
- CN202510938999.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-08
- Publication Date
- 2025-09-12
AI Technical Summary
The existing hybrid power flow controller cannot fully utilize the regulation capacity of the converter, resulting in excessive number of phase-shifting transformer operations and complex solution in multi-source ring networks.
The control strategy is that the converter first performs full load regulation, then the phase-shifting transformer takes action, and finally the converter performs reverse supplementary regulation. The adaptive regulation is achieved by executing the computer program through the processor.
Give full play to the regulation capability of the converter, reduce the number of operations of the phase-shifting transformer, improve the regulation accuracy, and adapt to multi-source complex ring networks.
Smart Images
Figure CN120638355A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of power systems, and in particular relates to a hybrid power flow controller and a control method and device thereof. Background Art
[0002] Today, the energy revolution is accelerating, and building a new power system based primarily on renewable energy has become an inevitable choice. However, the current flow regulators used in existing power systems do not simultaneously achieve the advantages of flexible regulation and low cost. Some scholars have proposed a hybrid power flow control system based on a phase-shifting transformer (PST) and a voltage source converter (i.e., a cascaded H-bridge converter). This system effectively combines the advantages of traditional electromagnetic mechanical devices with power electronics. On the one hand, it utilizes the passive electromagnetic device (i.e., phase-shifting transformer) to achieve large-scale discontinuous regulation, which has the advantages of low cost and high reliability, and can fully utilize the inherent regulation capabilities of the phase shifter. On the other hand, it utilizes the voltage source converter to achieve precise, rapid, and broadband continuous regulation, minimizing the configuration capacity of the voltage source device. This achieves technological breakthroughs in the overall insulation, volume, and cost of the hybrid power flow control equipment, and the system has significant technical and economic advantages.
[0003] Both the phase shifter and converter components of the hybrid power flow controller have the ability to regulate power flow. When designing the converter capacity, the frequent operation of the PST (Pulsating Steering Wheel) reduces the device's lifespan. Therefore, the converter capacity is designed to cover the capacity of both phase shifter gears. However, previously designed control strategies are based on a large-scale adjustment of the PST followed by supplementary regulation by the CHBC (Cascaded H-Bridge Converter). This fails to fully utilize the converter's regulation capacity to minimize the number of PST operations. Furthermore, the actual regulation process requires first determining the PST gear position, which has many degrees of freedom and is complex to solve in a multi-source ring network. Summary of the Invention
[0004] The purpose of the present invention is to provide a hybrid power flow controller and its control method and device to solve the technical problem in the prior art that the hybrid power flow controller cannot fully utilize the regulation capacity of the converter, resulting in excessive PST action times.
[0005] To solve the above technical problems, the present invention provides a technical solution for a control method of a hybrid power flow controller: a control method of a hybrid power flow controller, the method comprising:
[0006] S1. When the target power flow instruction is greater than the actual power flow of the line, the converter is controlled to increase the actual power flow of the line;
[0007] S2. If the target power flow command is still greater than the actual power flow of the line after the converter reaches the power flow regulation upper limit, increase the gear of the phase-shifting transformer to increase the actual power flow of the line until the actual power flow of the line is greater than the difference between the target power flow command and the power buffer threshold;
[0008] S3. After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to reduce the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
[0009] The beneficial effect of the above technical solution is that the technical solution of the control method of a hybrid power flow controller of the present invention is an improved invention. Different from the regulation strategy of the prior art that first adjusts the PST and then adjusts the converter, the present invention first adjusts the converter to full load, then the PST takes action, and finally the converter performs reverse supplementary regulation. This can fully utilize the regulation capacity of the converter, reduce the solution freedom, avoid solving the PST gear, and realize the adaptive regulation of the controller. The present invention solves the technical problem in the prior art that the hybrid power flow controller cannot fully utilize the regulation capacity of the converter, resulting in an excessive number of PST actions.
[0010] Furthermore, the method further comprises A and / or B;
[0011] A: In S2, if the converter reaches the upper limit of power flow regulation, the converter is controlled to increase the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, then the converter is kept in the current state and the current power flow control is exited;
[0012] B: In S3, after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
[0013] Furthermore, the method further comprises:
[0014] (1) When the target power flow instruction is smaller than the actual power flow of the line, the converter is controlled to reduce the actual power flow of the line;
[0015] (2) If the target power flow instruction is still smaller than the actual power flow of the line after the converter reaches the lower limit of the power flow regulation, the gear of the phase-shifting transformer is reduced to reduce the actual power flow of the line until the actual power flow of the line is smaller than the sum of the target power flow instruction and the power buffer threshold;
[0016] (3) After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to increase the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
[0017] Further, the method further comprises C and / or D;
[0018] C: In (2), if the converter reaches the lower limit of power flow regulation before the converter controls the converter to reduce the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the converter is kept in the current state and the current power flow control is exited;
[0019] D: In (3), after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
[0020] The present invention also provides a technical solution for a control device of a hybrid power flow controller: a control device of a hybrid power flow controller, comprising a processor, wherein the processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller as described above.
[0021] The present invention also provides a technical solution for a hybrid power flow controller: a hybrid power flow controller comprising a phase-shifting transformer and a converter, and also comprising a processor, wherein the processor is used to execute a computer program to implement the control method steps of the hybrid power flow controller as described above.
[0022] The present invention also provides a technical solution for a control method of a hybrid power flow controller: a control method of a hybrid power flow controller, the method comprising:
[0023] (1) When the target power flow instruction is smaller than the actual power flow of the line, the converter is controlled to reduce the actual power flow of the line;
[0024] (2) If the target power flow instruction is still smaller than the actual power flow of the line after the converter reaches the lower limit of the power flow regulation, the gear of the phase-shifting transformer is reduced to reduce the actual power flow of the line until the actual power flow of the line is smaller than the sum of the target power flow instruction and the power buffer threshold;
[0025] (3) After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to increase the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
[0026] The beneficial effect of the above technical solution is that the technical solution of the control method of a hybrid power flow controller of the present invention is an improved invention. Different from the regulation strategy of the prior art that first adjusts the PST and then adjusts the converter, the present invention first adjusts the converter to full load, then the PST takes action, and finally the converter performs reverse supplementary regulation. This can fully utilize the regulation capacity of the converter, reduce the solution freedom, avoid solving the PST gear, and realize the adaptive regulation of the controller. The present invention solves the technical problem in the prior art that the hybrid power flow controller cannot fully utilize the regulation capacity of the converter, resulting in an excessive number of PST actions.
[0027] Further, the method further comprises C and / or D;
[0028] C: In (2), if the converter reaches the lower limit of power flow regulation before the converter controls the converter to reduce the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the converter is kept in the current state and the current power flow control is exited;
[0029] D: In (3), after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
[0030] The present invention also provides a technical solution for a control device of a hybrid power flow controller: a control device of a hybrid power flow controller, comprising a processor, wherein the processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller as described above.
[0031] The present invention also provides a technical solution for a hybrid power flow controller: a hybrid power flow controller comprising a phase-shifting transformer and a converter, and also comprising a processor, wherein the processor is used to execute a computer program to implement the control method steps of the hybrid power flow controller as described above. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 A topological diagram of a hybrid power flow controller in an embodiment of the present invention;
[0033] Figure 2 Schematic diagram of an application scenario of a hybrid power flow controller in an embodiment of the present invention;
[0034] Figure 3 Flow chart of a control method of a hybrid power flow controller in an embodiment of the hybrid power flow controller of the present invention;
[0035] Figure 4 Schematic diagram of the dynamic adjustment of power flow waveform in the hybrid power flow controller embodiment of the present invention;
[0036] Figure 5 Schematic diagram of the waveform of the smoothed new energy power fluctuation in the hybrid power flow controller embodiment of the present invention. DETAILED DESCRIPTION
[0037] Unlike the prior art strategy of adjusting the PST first and then the converter, the present invention first regulates the converter at full load, then activates the PST, and finally uses the converter to reverse and supplement the regulation. This fully utilizes the converter's regulation capabilities, reduces the degrees of freedom in the solution, avoids solving for the PST gear, and achieves adaptive regulation of the controller. This solves the technical problem of prior art hybrid power flow controllers that fail to fully utilize the converter's regulation capacity, resulting in excessive PST activation.
[0038] Hybrid power flow controller implementation method:
[0039] A hybrid power flow controller, such as Figure 1 As shown, including a phase shift transformer (PST) (ie Figure 1 The ST and ET parts in the circuit) and the cascaded H-bridge converter (CHBC) as a voltage source converter, CHBC is connected in series with the excitation transformer (i.e. Figure 1 The low-voltage side of the ET in the circuit controls its output voltage amplitude to assist the phase shifter in regulating the power flow.
[0040] The hybrid power flow controller of this embodiment can be applied to Figure 2 In the application scenario of the double-circuit line shown, the power flow distribution of the line is adjusted by adjusting the gear position of the phase-shifting transformer and the voltage command of the converter (i.e., the q-axis reference voltage) in the hybrid power flow controller.
[0041] The hybrid power flow controller further includes a processor configured to execute a computer program to implement the control method steps of the hybrid power flow controller as described below; Figure 3 As shown, the control method of the hybrid power flow controller includes:
[0042] By comparing the power flow target instruction P ref The actual power flow P L2 The difference between the two is used to generate the dispatching instructions for the converter and phase shifter according to the difference.
[0043] Specifically, when (P ref -P L2 )>0, that is, P ref >P L2 When the converter starts to adjust, the line power flow increases until P L2 Close to P ref Or the converter reaches the rated capacity; if the converter is fully loaded, P L2 Still not reaching P ref, then PST starts to work, adjust the PST gear (ie Figure 3 OLTC, On-load Tap-hanger), continue to increase the power flow until P L2 Satisfy the following formula: P L2 >P ref -P bu , PST stops the action; at this time, if |P L2 -P ref |≤P bu , switch to the converter for reverse regulation, that is, control the converter to reduce the line flow until P L2 Close to P ref , that is, satisfying |P L2 -P ref |≤P bu .
[0044] When (P ref -P L2 )<0, that is, P ref <P L2 When the inverter starts to adjust, the line power flow is reduced until P L2 Close to P ref Or the converter reaches the rated capacity; if the converter is fully loaded, P L2 Still not reaching P ref , then PST starts to act, adjust the PST gear, continue to reduce the current, until P L2 Satisfy the following formula: P L2 <P ref +P bu , PST stops the action; at this time, if |P L2 -P ref |≤P bu , switch to the converter for reverse regulation, that is, control the converter to increase the line flow until P L2 Close to P ref , that is, satisfying |P L2 -P ref |≤P bu .
[0045] Among them, P bu >0, indicating the power buffer threshold, P bu The value of is usually determined according to the fluctuation range of actual power in steady state.
[0046] The simulation waveform of the power flow is adjusted based on the control method of the hybrid power flow controller. Figure 4 As shown, in chronological order:
[0047] Phase 1: In the initial stage, the CHBC is charged with the energy from the grid, so that the capacitor voltage of the CHBC reaches the rated value;
[0048] Phase 2: After CHBC charging is completed, CHBC controls the power flow and starts to increase the line power flow P L2 ;
[0049] Phase 3: When CHBC is fully loaded, due to P L2 Still not reaching P ref , and then regulated by PST, PST makes the power P L2 Change; PST gear action: gradually increase from 0 gear to 4 gear, when 4 gear, P L2 Just beyond P ref ;
[0050] When the trend L2 Just beyond P ref And the difference between the two does not exceed P bu , and then CHBC performs reverse regulation to supplement the current (i.e. reduce it). Through the cooperation of CHBC and PST, P L2 Reach P ref =290MW.
[0051] When the instruction P ref After changing from 290MW to 190MW, HPFC then performs phase 2 and phase 3 in sequence to bring the power flow to 190MW. Similarly, when the power flow target is changed again to 240MW, the power flow is tracked again by HPFC.
[0052] The simulation waveform of smoothing power fluctuation based on the control method of the hybrid power flow controller is as follows: Figure 5 As shown, set the adjustment target (i.e. Figure 5 The power output (shown by the middle blue line) is 300MW. When renewable energy power fluctuates, the HPFC, through the coordinated cooperation of the PST and CHBC, suppresses power fluctuations, keeping power fluctuations close to the target power. Without the HPFC, the power fluctuations are large, approaching 97MW. With the assistance of the CHBC, the power is accurately maintained at 300MW, with a suppression efficiency of 84.536%, effectively extending the service life of the PST.
[0053] Implementation method 1 of hybrid power flow controller:
[0054] A control method for a hybrid power flow controller, comprising: S1. When a target power flow command is greater than the actual power flow of a line, controlling the converter to increase the actual power flow of the line; S2. If, after the converter reaches the power flow regulation upper limit, the target power flow command is still greater than the actual power flow of the line, increasing the gear of the phase-shifting transformer to increase the actual power flow of the line until the actual power flow of the line exceeds the difference between the target power flow command and a power buffer threshold; S3. After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow command is greater than the power buffer threshold, controlling the converter to reduce the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow command is lower than the power buffer threshold. The specific control method of the hybrid power flow controller has been sufficiently explained in the above-mentioned hybrid power flow controller and will not be repeated here.
[0055] Implementation method 2 of hybrid power flow controller:
[0056] A control method for a hybrid power flow controller, the method comprising: (1) when a target power flow instruction is less than an actual power flow of a line, controlling a converter to reduce the actual power flow of the line; (2) if the target power flow instruction is still less than the actual power flow of the line after the converter reaches the power flow regulation lower limit, reducing the gear of a phase-shifting transformer to reduce the actual power flow of the line until the actual power flow of the line is less than the sum of the target power flow instruction and a power buffer threshold; (3) after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is greater than the power buffer threshold, controlling a converter to increase the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is less than the power buffer threshold. The specific control method of the hybrid power flow controller has been sufficiently explained in the above hybrid power flow controller and will not be repeated here.
[0057] Implementation method of control device of hybrid power flow controller:
[0058] A control device for a hybrid power flow controller includes a processor configured to execute a computer program to implement the control method steps of the hybrid power flow controller described above. The specific control method of the hybrid power flow controller has been described in sufficient detail in the above hybrid power flow controller embodiment and will not be repeated here.
[0059] Specifically, the processor may be a CPU, or other general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor may also be a processor that supports the Advanced RISC Machine (ARM) architecture.
[0060] The present invention has the following characteristics:
[0061] This invention issues action commands to the PST and CHBC by determining the difference between the target and current power flows. The CHBC is prioritized over the PST, allowing the CHBC to regulate at full load first, followed by the PST's on-load voltage regulation, and the CHBC to perform supplementary regulation, thereby achieving precise power flow regulation. Prioritizing the CHBC first maximizes its regulatory capabilities, reducing the number of PST actions and thus extending the device's lifespan. It also reduces the HPFC's solution freedom, avoiding the need to solve the PST's gears, making it suitable for complex multi-source ring networks and various application scenarios.
[0062] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments without inventive effort, or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.
Claims
1. A control method for a hybrid power flow controller, characterized in that: The method includes: S1. When the target power flow instruction is greater than the actual power flow of the line, the converter is controlled to increase the actual power flow of the line; S2. If the target power flow command is still greater than the actual power flow of the line after the converter reaches the power flow regulation upper limit, increase the gear of the phase-shifting transformer to increase the actual power flow of the line until the actual power flow of the line is greater than the difference between the target power flow command and the power buffer threshold; S3. After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to reduce the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
2. The control method of the hybrid power flow controller according to claim 1, characterized in that: The method further comprises A and / or B; A: In S2, if the converter reaches the upper limit of power flow regulation, the converter is controlled to increase the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, then the converter is kept in the current state and the current power flow control is exited; B: In S3, after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
3. The control method of the hybrid power flow controller according to claim 1 or 2, characterized in that: The method further includes: (1) When the target power flow instruction is smaller than the actual power flow of the line, the converter is controlled to reduce the actual power flow of the line; (2) If the target power flow instruction is still smaller than the actual power flow of the line after the converter reaches the lower limit of the power flow regulation, the gear of the phase-shifting transformer is reduced to reduce the actual power flow of the line until the actual power flow of the line is smaller than the sum of the target power flow instruction and the power buffer threshold; (3) After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to increase the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
4. The control method of the hybrid power flow controller according to claim 3, characterized in that: The method further includes C and / or D; C: In (2), if the converter reaches the lower limit of power flow regulation before the converter controls the converter to reduce the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the converter is kept in the current state and the current power flow control is exited; D: In (3), after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
5. A control method for a hybrid power flow controller, characterized in that: The method includes: (1) When the target power flow instruction is smaller than the actual power flow of the line, the converter is controlled to reduce the actual power flow of the line; (2) If the target power flow instruction is still smaller than the actual power flow of the line after the converter reaches the lower limit of the power flow regulation, the gear of the phase-shifting transformer is reduced to reduce the actual power flow of the line until the actual power flow of the line is smaller than the sum of the target power flow instruction and the power buffer threshold; (3) After the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual line power flow and the target power flow instruction is greater than the power buffer threshold, the converter is controlled to increase the actual line power flow until the absolute value of the difference between the actual line power flow and the target power flow instruction is lower than the power buffer threshold.
6. The control method of the hybrid power flow controller according to claim 5, characterized in that: The method further includes C and / or D; C: In (2), if the converter reaches the lower limit of power flow regulation before the converter controls the converter to reduce the actual power flow of the line until the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the converter is kept in the current state and the current power flow control is exited; D: In (3), after the phase-shifting transformer is adjusted, if the absolute value of the difference between the actual power flow of the line and the target power flow instruction is lower than the power buffer threshold, the current power flow control is exited.
7. A control device for a hybrid power flow controller, comprising a processor, characterized in that: The processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller according to any one of claims 1 to 4.
8. A control device for a hybrid power flow controller, comprising a processor, characterized in that: The processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller according to claim 5 or 6.
9. A hybrid power flow controller, comprising a phase-shifting transformer and a converter, and also comprising a processor, characterized in that: The processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller according to any one of claims 1 to 4.
10. A hybrid power flow controller, comprising a phase-shifting transformer and a converter, and also comprising a processor, characterized in that: The processor is configured to execute a computer program to implement the control method steps of the hybrid power flow controller according to claim 5 or 6.