Direct current peak regulation operation control and performance optimization method based on converter valve

Abstract

The invention belongs to the technical field of high-voltage direct-current transmission control, and relates to a direct-current peak regulation operation control and performance optimization method based on a converter valve. The method comprises the following steps: controlling a trigger angle of a rectification side and an extinction angle of an inversion side of an HCC converter valve within a set range by operating a tap switch of a converter transformer; obtaining an initially set on-load tap-changer gear action set value, an alternating current filter switching action set value and a direct current minimum power set value of an HCC converter valve; and according to the day-ahead direct current power curve, the electric power market transaction result, the dynamic modulation trigger angle and the extinction angle of the inverter side, the dynamic peak regulation capacity of the ultra-high voltage direct current based on the HCC converter valve is obtained. According to the invention, the peak regulation capacity is increased, and the action times of the tap switch are reduced; and the trigger angle and the extinction angle of the HCC converter valve are flexibly and freely adjusted, so that the phenomenon of current interruption is avoided, the peak regulation capacity is further increased, and the stability and the safety of direct-current peak regulation operation are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-voltage direct current transmission control, and in particular, relates to a direct current peak-shaving operation control and performance optimization method based on a converter valve. Background Art

[0002] With the gradual increase in the proportion of new energy installed capacity and the gradual decrease in the proportion of thermal power installed capacity, the problems faced by the peak load regulation of the power grid are becoming increasingly serious, and the problem of insufficient peak load regulation resources is becoming increasingly prominent. The power regulation capability of UHV DC can provide certain peak load regulation resources for the power grid, but there are many factors that restrict the peak load regulation operation. First, the regulation of DC power will cause the on-load tap changer of the converter transformer to operate frequently, reducing the life of the on-load tap changer of the converter transformer, thereby affecting the reliability of the converter transformer; second, the regulation of DC power will cause the AC filter to be repeatedly switched on and off, and the repeated switching of the AC filter is likely to cause voltage fluctuations in the near area, resulting in phase commutation failure; third, because the grid phase-commutation converter is limited by the DC intermittent current, in order to ensure the stability and safety of DC operation, there is a minimum DC operating power, the peak load regulation operation range is limited, and there is still a minimum operating power. In addition, due to the participation of UHV DC in medium- and long-term, day-ahead power market and intraday power market transactions, the release of UHV DC peak load regulation resources is further restricted due to economic regulation factors. Therefore, in order to solve the problem of grid peak load regulation under the background of new power system construction, a DC peak load regulation method with better peak load regulation performance is urgently needed. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a DC peak-shaving operation control and performance optimization method based on a converter valve, including DC peak-shaving operation control and DC peak-shaving performance optimization;

[0004] DC peak load operation control includes:

[0005] According to the rise and fall of DC power, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC converter valve are controlled within the set range by operating the tap switch of the converter transformer;

[0006] Determine the relationship between rated voltage, arc extinction angle and tap changer position, and control the on-load tap changer action according to the trend relationship between current and tap changer position;

[0007] The switching of the AC filter is controlled according to the trend relationship between the rise and fall of DC power and the switching capacity of the AC filter;

[0008] DC peak load performance optimization, including:

[0009] According to the DC operation mode, determine the setting range of the trigger angle on the rectifier side and the arc extinction angle on the inverter side allowed by the HCC converter valve;

[0010] Combining the DC voltage control dead zone with the operation mode of the phase shifters at the transmitting and receiving ends, the initial setting of the on-load tap changer gear action setting value, the AC filter switching action setting value and the DC minimum power setting value of the HCC converter valve are obtained;

[0011] According to the day-ahead DC power curve and the results of power market transactions, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC converter valve are dynamically modulated in the control loop to obtain the dynamic peak-shaving capacity of the UHV DC based on the HCC converter valve.

[0012] Based on the above technical solution, the present invention can also be improved as follows.

[0013] Further, suppose U d is the DC voltage, U dio is the no-load voltage, U dioN is the rated no-load voltage, I d is the DC current, I dN is the rated DC current, is the angle, k is the on-load tap changer gear difference, T cpN is the rated position of the tap changer, T cp is the actual position of the tap changer. The relationship between the rated voltage, arc extinction angle and the tap changer position is:

[0014]

[0015] U dio =U dioN 1+k(T cpN -T cp ).

[0016] Furthermore, let the DC current be I d , the tap changer position is T, the trend relationship coefficient between DC current and tap changer position is k1, then:

[0017] T=k1I d .

[0018] Furthermore, let the rise and fall of DC power be ΔP d , the switching capacity of the AC filter is H, the trend relationship coefficient between the rise and fall of DC power and the switching capacity of the AC filter is k2, then:

[0019] H=k2ΔP d .

[0020] The beneficial effects of the present invention are as follows: the ultra-high voltage direct current based on HCC of the present invention utilizes the principle of recovery-enhanced natural commutation to expand the direct current power regulation range, thereby increasing the peak-shaving capacity; at the same time, within the same direct current power regulation range, the ultra-high voltage direct current based on HCC reduces the number of tap switch actions; the ultra-high voltage direct current based on HCC can reduce the configuration capacity of the AC filter field to less than 40% of the ultra-high voltage direct current based on LCC; the ultra-high voltage direct current based on HCC has the excellent characteristic of flexible power control, and the flexible and free adjustment of the trigger angle and the arc extinction angle of the HCC converter valve can avoid the current discontinuity phenomenon to the greatest extent, thereby increasing the peak-shaving capacity and ensuring the stability and safety of direct current peak-shaving operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a DC peak load regulation operation control and performance optimization method based on a converter valve provided in Example 1 of the present invention;

[0022] Figure 2 It is a schematic diagram of the trend relationship between DC current and tap changer position;

[0023] Figure 3 This is a schematic diagram of the trend relationship between the rise and fall of DC power and the switching capacity of the AC filter. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] As an example, Figure 1 As shown, in order to solve the above technical problems, this embodiment provides a DC peak-shaving operation control and performance optimization method based on a converter valve, including DC peak-shaving operation control and DC peak-shaving performance optimization;

[0026] DC peak load operation control includes:

[0027] According to the rise and fall of DC power, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC (Hybrid Commutated Converter) converter valve are controlled within the set range by operating the tap switch of the converter transformer;

[0028] Determine the relationship between rated voltage, arc extinction angle and tap changer position, and control the on-load tap changer action according to the trend relationship between current and tap changer position;

[0029] The switching of the AC filter is controlled according to the trend relationship between the rise and fall of DC power and the switching capacity of the AC filter;

[0030] DC peak load performance optimization, including:

[0031] According to the DC operation mode, determine the setting range of the trigger angle on the rectifier side and the arc extinction angle on the inverter side allowed by the HCC converter valve;

[0032] Combining the DC voltage control dead zone with the operation mode of the phase shifters at the transmitting and receiving ends, the initial setting of the on-load tap changer gear action setting value, the AC filter switching action setting value and the DC minimum power setting value of the HCC converter valve are obtained;

[0033] According to the day-ahead DC power curve and the results of power market transactions, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC converter valve are dynamically modulated in the control loop to obtain the dynamic peak-shaving capacity of the UHV DC based on the HCC converter valve.

[0034] In actual application, UHV DC operation based on LCC (Line Commutated Converter, grid-commutated converter valve) usually controls the trigger angle on the rectifier side to 14°±2.5°, and the arc extinction angle on the inverter side to 14±2.5° to 18°±2.5°. According to the increase or decrease of DC power, the trigger angle on the rectifier side and the arc extinction angle on the inverter side are controlled within the range by operating the tap switch of the converter transformer.

[0035] Optionally, let U d is the DC voltage, U dio is the no-load voltage, U dioN is the rated no-load voltage, I d is the DC current, I dN is the rated DC current, is the angle, k is the on-load tap changer gear difference, T cpN is the rated position of the tap changer, T cp is the actual position of the tap changer. The relationship between the rated voltage, arc extinction angle and the tap changer position is:

[0036]

[0037] U dio =U dioN 1+k(T cpN -T cp ).

[0038] Therefore, according to the relationship between rated voltage, arc extinction angle and tap changer position, the trend relationship between DC current and tap changer can be obtained based on actual engineering examples, as shown in the attached figure. Figure 2As shown, L1 is the switching capacity of the AC filter of the UHV DC based on HCC, and L2 is the switching capacity of the AC filter of the UHV DC based on LCC. The figure shows the difference between the UHV DC based on HCC and the UHV DC based on LCC.

[0039] Optionally, let the DC current be I d , the tap changer position is T, the trend relationship coefficient between DC current and tap changer position is k1, then:

[0040] T=k1I d .

[0041] As attached Figure 3 The trend relationship between the rise and fall of DC power and the switching capacity of the AC filter is shown. L1 is the switching capacity of the AC filter based on HCC UHV DC, and L2 is the switching capacity of the AC filter based on LCC UHV DC. It can be obtained that:

[0042] (1) UHV DC based on HCC uses the method of restoring and enhancing natural commutation to expand the DC power regulation range, thereby increasing the peak load capacity;

[0043] (2) Within the same DC power regulation range, UHV DC based on HCC reduces the number of tap changer operations.

[0044] Optionally, let the DC power rise and fall be ΔP d , the switching capacity of the AC filter is H, the trend relationship coefficient between the rise and fall of DC power and the switching capacity of the AC filter is k2, then:

[0045] H=k2ΔP d .

[0046] Due to the superposition of ripple on DC current, when the average value of DC current is less than a certain value, the DC current waveform may be discontinuous and the DC current may be intermittent. The discontinuity of DC current will generate overvoltage on inductive components such as converter transformers and smoothing reactors. The UHV DC based on HCC has the excellent characteristic of flexible power control and can flexibly and freely adjust the trigger angle and arc extinction angle to avoid the phenomenon of current discontinuity to the greatest extent, thereby increasing its peak-shaving capacity.

[0047] When optimizing the DC peak-shaving performance, the setting range of the trigger angle and arc-out angle allowed by the HCC converter valve is determined according to the DC operation mode set a few days ago, so as to obtain the initial setting of the on-load tap changer gear action setting value, the AC filter switching action setting value and the DC minimum power setting value of the HCC converter valve. The AC filter switching also affects the action of the on-load tap changer, and the HCC DC minimum power also affects the AC filter switching setting. If a DC dynamic voltage control strategy is configured, the strategy will also affect the DC voltage control dead zone, and further affect the setting of the trigger angle and arc-out angle of the HCC converter valve. If a phase regulator is configured at the sending and receiving ends, the operation mode of the phase regulator will also affect the setting of the trigger angle and arc-out angle of the HCC converter valve. According to the DC power curve arranged a few days ago and the results of the power market transaction, under the influence of the above factors, in the control loop, the trigger angle and arc-out angle limits of the HCC converter valve are dynamically modulated, and finally the dynamic peak-shaving capacity of the UHV DC based on the HCC converter valve is obtained, the peak-shaving resources are expanded and the peak-shaving of the power grid is participated.

[0048] The ultra-high voltage direct current based on HCC of the present invention utilizes the principle of recovery-enhanced natural commutation to expand the direct current power regulation range, thereby increasing the peak-shaving capacity. Meanwhile, within the same direct current power regulation range, the ultra-high voltage direct current based on HCC reduces the number of tap switch actions; the ultra-high voltage direct current based on HCC can reduce the configuration capacity of the AC filter field to less than 40% of the ultra-high voltage direct current based on LCC; the ultra-high voltage direct current based on HCC has the excellent characteristic of flexible power control, and the flexible and free adjustment of the trigger angle and the arc extinction angle of the HCC converter valve can avoid the phenomenon of current discontinuity to the greatest extent, thereby increasing the peak-shaving capacity and ensuring the stability and safety of direct current peak-shaving operation.

[0049] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A DC peak load regulation operation control and performance optimization method based on a converter valve, characterized in that: Including DC peak load regulation operation control and DC peak load regulation performance optimization; DC peak load operation control includes: According to the rise and fall of DC power, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC converter valve are controlled within the set range by operating the tap switch of the converter transformer; Determine the relationship between rated voltage, arc extinction angle and tap changer position, and control the on-load tap changer action according to the trend relationship between current and tap changer position; The switching of the AC filter is controlled according to the trend relationship between the rise and fall of DC power and the switching capacity of the AC filter; DC peak load performance optimization, including: According to the DC operation mode, determine the setting range of the trigger angle on the rectifier side and the arc extinction angle on the inverter side allowed by the HCC converter valve; Combining the DC voltage control dead zone with the operation mode of the phase shifters at the transmitting and receiving ends, the initial setting of the on-load tap changer gear action setting value, the AC filter switching action setting value and the DC minimum power setting value of the HCC converter valve are obtained; According to the day-ahead DC power curve and the results of power market transactions, the trigger angle on the rectifier side and the arc extinction angle on the inverter side of the HCC converter valve are dynamically modulated in the control loop to obtain the dynamic peak-shaving capacity of the UHV DC based on the HCC converter valve.

2. The DC peak load regulation operation control and performance optimization method based on converter valve according to claim 1 is characterized in that: Let U d is the DC voltage, U dio is the no-load voltage, U dioN is the rated no-load voltage, I d is the DC current, I dN is the rated DC current, is the angle, k is the on-load tap changer gear difference, T cpN is the rated position of the tap changer, T cp is the actual position of the tap changer. The relationship between the rated voltage, arc extinction angle and the tap changer position is: U dio =U dioN 1+k(T cpN -T cp )。 3. The DC peak load regulation operation control and performance optimization method based on converter valve according to claim 1 is characterized in that: Let the DC current be I d , the tap changer position is T, the trend relationship coefficient between DC current and tap changer position is k1, then: T=k1I d 。 4. The DC peak load regulation operation control and performance optimization method based on converter valve according to claim 1 is characterized in that: Assume that the rise and fall of DC power is ΔP d , the switching capacity of the AC filter is H, the trend relationship coefficient between the rise and fall of DC power and the switching capacity of the AC filter is k2, then: H=k2ΔP d 。

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