CN102185331A

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Info

Publication number: CN102185331A
Application number: CN2011101084462A
Authority: CN
Inventors: 邓占锋; 周飞; 赵国量; 蔡林海; 荆平; 胡为进; 刘隽; 陆如; 仇琦玮; 沈冬
Original assignee: China Electric Power Research Institute Co Ltd CEPRI; Shanghai Municipal Electric Power Co
Current assignee: China Electric Power Research Institute Co Ltd CEPRI; Shanghai Municipal Electric Power Co
Priority date: 2011-04-28
Filing date: 2011-04-28
Publication date: 2011-09-14
Anticipated expiration: 2031-04-28
Also published as: CN102185331B

Abstract

Translated fromChinese

本发明涉及一种基于零序电压的换流链平均直流电压的控制方法，将所有换流链中任意两相换流链的平均直流电压与所有链节直流电压的平均值相减得到两相换流链的平均直流电压偏差，该偏差经过比例积分调节器得到对应相换流链的有功功率偏差；将其结合换流器输出的正序电流的有效值和相位经过零序电压指令运算得到换流器的零序电压指令，最后通过乘法运算得到三相换流链的零序电压指令，其作为换流链平均直流电压控制的调制波电压参考值控制换三相流链输出构成闭环控制。该方法根据任意两相平均直流电压偏差调节零序电压，可保证三相功率满足要求，有效解决换流链平均直流电压不平衡的问题，具有原理简单明确、性能优良、适用范围广、实用性强等优点。

The invention relates to a method for controlling the average DC voltage of a commutation chain based on zero-sequence voltage. The average DC voltage of any two-phase commutation chain in all commutation chains is subtracted from the average value of the DC voltage of all chain links to obtain a two-phase The average DC voltage deviation of the commutation chain, the deviation is obtained through the proportional integral regulator to obtain the active power deviation of the corresponding phase commutation chain; it is combined with the effective value and phase of the positive sequence current output by the converter and obtained through the zero sequence voltage command operation The zero-sequence voltage command of the converter is finally multiplied to obtain the zero-sequence voltage command of the three-phase commutation chain, which is used as the reference value of the modulated wave voltage for the average DC voltage control of the commutation chain to control the output of the three-phase current chain to form a closed-loop control . This method adjusts the zero-sequence voltage according to any two-phase average DC voltage deviation, which can ensure that the three-phase power meets the requirements and effectively solve the problem of unbalanced average DC voltage in the commutation chain. It has simple and clear principles, excellent performance, wide application range, and practicality Strong and other advantages.

Description

Translated fromChinese

一种基于零序电压的换流链平均直流电压的控制方法A control method for the average DC voltage of the commutation chain based on zero-sequence voltage

技术领域technical field

本发明属于电力电子装置控制技术领域，具体涉及一种基于零序电压的换流链平均直流电压的控制方法，可应用于链式换流器的直流电压控制方法。The invention belongs to the technical field of power electronic device control, and in particular relates to a zero-sequence voltage-based control method for the average DC voltage of a commutation chain, which can be applied to the DC voltage control method of a chain-type converter.

背景技术Background technique

链式换流器在工程中应用广泛，其由多个单相换流链构成，每个单相静止同步补偿器中包括单相换流链，每个单相换流链由至少一个单相模块(即图1中的级联模组1......n)构成，每个单相模组包括至少一个链节，链节与链节之间可通过串联或并联相连接，每个链节包括H桥型电压源换流器。The chain-type converter is widely used in engineering, and it is composed of multiple single-phase commutation chains. Each single-phase static synchronous compensator includes a single-phase commutation chain, and each single-phase commutation chain consists of at least one single-phase modules (i.e. cascaded modules 1...n in Fig. The chain links consist of H-bridge voltage source converters.

链式换流器具有诸多优点，可以实现独立分相控制，有利于解决系统的相间平衡问题，在系统受到扰动时，更好地提供电压支撑。其所有链接的基本单元结构完全相同，可以实现模块化设计，便于扩容和维护，并避免了因开关器件直接串并联使用而产生的问题。链式换流器采用普通变压器接入系统，避免了多重化变压器带来的问题，减小了占地面积，降低了装置成本。此外，多电平链式换流器输出的谐波可忽略，不需要滤波器。The chain-link converter has many advantages, and can realize independent phase-separation control, which is beneficial to solve the phase-to-phase balance problem of the system, and better provide voltage support when the system is disturbed. The basic unit structure of all links is exactly the same, which can realize modular design, facilitate expansion and maintenance, and avoid problems caused by the direct use of switching devices in series and parallel. The chain-type converter adopts ordinary transformers to connect to the system, which avoids the problems caused by multiple transformers, reduces the occupied area, and reduces the cost of the device. In addition, the output harmonics of the multilevel chain-link converter are negligible and no filter is needed.

然而，链式结构引发的问题是直流侧电容电压波动剧烈及直流电容电压不平衡，协调控制难度较大。直流电压平衡控制通常从能量角度着手，控制换流链间及链节之间的能量平衡，而调节电容并联损耗及变直流电压控制方法瞬态响应较慢，调节范围受限且损耗较大。针对链式换流器直流电压平衡问题，工程中通常采用三级直流电压控制，第一级为全局平均直流电压控制，解决装置整体直流侧电压的稳定问题；第二级控制为换流链平均直流电压控制，实现相间直流侧电压平衡；第三级控制为链节直流电压控制，实现链节平衡。上述直流电压平衡控制方法可以通过PI调节器构成id和iq的电流闭环，使其在d轴和q轴方向上保持恒定，通过控制链式换流器交换的有功和无功功率达到平衡电容电压目的。但实现三级直流控制时若控制量或反馈量选择不当将导致控制的速度和精度无法满足实际要求。其中第二级换流链平均直流电压控制决定换流器能否实现三相平衡，并影响第三级控制的效果和速度。采用无功电流反馈量进行三相平衡控制，控制原理不明确，控制效果不明显。所述内容提出基于零序电压的换流链平均直流电压控制策略，具有控制目标明确，响应速度快，控制效果良好等优点。However, the problem caused by the chain structure is that the capacitor voltage on the DC side fluctuates violently and the DC capacitor voltage is unbalanced, making coordinated control difficult. DC voltage balance control usually starts from the energy point of view, and controls the energy balance between the commutation chains and between the chain links, while the method of adjusting the parallel loss of capacitors and variable DC voltage control method has slow transient response, limited adjustment range and large loss. Aiming at the DC voltage balance problem of chain-type converters, three-level DC voltage control is usually used in engineering. The first level is the global average DC voltage control to solve the stability problem of the overall DC side voltage of the device; the second level control is the average value of the converter chain. DC voltage control to achieve phase-to-phase DC side voltage balance; the third level of control is chain link DC voltage control to achieve chain link balance. The above DC voltage balance control method can form a current closed loop of id and iq through a PI regulator to keep it constant in the d-axis and q-axis directions, and achieve a balanced capacitor voltage by controlling the active and reactive power exchanged by the chain-link converter Purpose. However, if the control quantity or feedback quantity is not selected properly when realizing the three-level DC control, the speed and precision of the control will not meet the actual requirements. Among them, the average DC voltage control of the second-level converter chain determines whether the converter can achieve three-phase balance, and affects the effect and speed of the third-level control. Using reactive current feedback to carry out three-phase balance control, the control principle is not clear, and the control effect is not obvious. The content proposes an average DC voltage control strategy of the converter chain based on zero-sequence voltage, which has the advantages of clear control objectives, fast response speed, and good control effect.

发明内容Contents of the invention

为了克服现有技术的上述缺陷，本发明的提出一种基于零序电压的换流链平均直流电压的控制方法，该控制方法通过调节任意两相的功率偏差达到补偿各相换流链平均直流电压不平衡的目的。In order to overcome the above-mentioned defects of the prior art, the present invention proposes a control method for the average DC voltage of the commutation chain based on zero-sequence voltage. purpose of voltage unbalance.

本发明的基于零序电压的换流链平均直流电压的控制方法是通过下述技术方案实现的：The control method of the average DC voltage of the commutation chain based on the zero-sequence voltage of the present invention is realized through the following technical scheme:

一种基于零序电压的换流链平均直流电压的控制方法，其特征在于：该控制方法是将所有换流链中任意两相换流链的平均直流电压与所有链节直流电压的平均值相减得到两相换流链的平均直流电压偏差，经过比例-积分调节器，通过两相换流链的平均直流电压偏差得到对应相换流链的有功功率偏差；有功功率偏差结合换流器输出的正序电流的有效值和相位经过零序电压指令运算环节，得到换流器的零序电压指令，进而通过乘法运算得到三相换流链的零序电压指令；三相换流链的零序电压指令作为换流链平均直流电压控制的调制波电压参考值控制换三相流链输出构成闭环控制。A method for controlling the average DC voltage of a commutation chain based on zero-sequence voltage, characterized in that the control method is to combine the average DC voltage of any two-phase commutation chain in all commutation chains with the average value of the DC voltage of all chain links The average DC voltage deviation of the two-phase commutation chain is obtained by subtraction, and the active power deviation of the corresponding phase commutation chain is obtained through the proportional-integral regulator through the average DC voltage deviation of the two-phase commutation chain; the active power deviation combined with the converter The effective value and phase of the output positive-sequence current go through the zero-sequence voltage command operation link to obtain the zero-sequence voltage command of the converter, and then obtain the zero-sequence voltage command of the three-phase commutation chain through multiplication; the three-phase commutation chain The zero-sequence voltage command is used as the reference value control of the modulated wave voltage for the average DC voltage control of the commutation chain to commutate the output of the three-phase current chain to form a closed-loop control.

其中，所述零序电压指令运算环节为：将有功功率偏差与换流器输出的正序电流的有效值和相位代入下式中求取换流器的零序电压指令u_N，再将该指令u_N平均分配到三相换流链中，得到三相换流链的零序电压指令u_{N_a}，u_{N_b}，u_{N_c}：Wherein, the zero-sequence voltage command operation link is: substituting the active power deviation and the effective value and phase of the positive-sequence current output by the converter into the following formula to obtain the zero-sequence voltage command u_N of the converter, and then The instruction u_N is evenly distributed to the three-phase commutation chain, and the zero-sequence voltage instruction u_{N_a} , u_{N_b} , u_{N_c} of the three-phase commutation chain are obtained:

${u u}_{N N} = = - - \frac{Δ Δ {P P}_{A A}^{* *}}{\frac{\sqrt{33}}{22} {I I}_{p p}} cos cos ((ωt ωt + + {φ φ}_{p p} + + \frac{22 π π}{33})) - - \frac{Δ Δ {P P}_{B B}^{* *}}{\frac{\sqrt{33}}{22} {I I}_{p p}} cos cos ((ωt ωt + + {φ φ}_{p p}))$

式中，为任意两相换流链的有功功率偏差；I_p、

为正序电流的有效值和相位，ω为基波角频率，t为时间。In the formula, is the active power deviation of any two-phase commutation chain; I_p ,

is the effective value and phase of the positive sequence current, ω is the fundamental angular frequency, and t is the time.

其中，所述乘法运算是用换流器的零序电压u_N乘以1/3，所得值分别作为三相换流链的零序电压指令u_{N_a}，u_{N_b}，u_{N_c}，即三相换流链的零序电压指令u_{N_a}、u_{N_b}、u_{N_c}相等。Wherein, the multiplication operation is to multiply the zero-sequence voltage u_N of the converter by 1/3, and the obtained values are respectively used as the zero-sequence voltage commands u_{N_a} , u_{N_b} , u_{N_c} of the three-phase commutation chain, that is, the three-phase commutation The zero-sequence voltage commands u_{N_a} , u_{N_b} and u_{N_c} of the flow chain are equal.

本发明的控制方法具有以下优点：The control method of the present invention has the following advantages:

1)根据任意两相直流电压平均值偏差调节零序电压，即可保证三相功率满足要求；1) Adjust the zero-sequence voltage according to the average deviation of any two-phase DC voltage to ensure that the three-phase power meets the requirements;

2)采用该种控制方法的链式STATCOM控制原理简单明确，控制性能优良；2) The chained STATCOM control principle using this control method is simple and clear, and the control performance is excellent;

3)所述控制方法适用于采用链式级联H桥换流器的其他FACTS装置，适用范围宽广；3) The control method is applicable to other FACTS devices adopting chain-type cascaded H-bridge converters, and has a wide application range;

4)所述控制方法有效地解决了换流链平均直流电压不平衡的问题，具有很强的工程实用价值。4) The control method effectively solves the problem of unbalanced average DC voltage of the converter chain, and has strong engineering practical value.

附图说明Description of drawings

图1是级联H桥链式STATCOM主电路拓扑结构图；Figure 1 is a topological structure diagram of the cascaded H-bridge chained STATCOM main circuit;

图2是本发明的链式换流器平均直流电压控制框图；Fig. 2 is the chain-type converter average DC voltage control block diagram of the present invention;

图3是链式换流器零序电压指令运算的实现框图。Figure 3 is a block diagram of the implementation of the zero-sequence voltage command operation of the chain-type converter.

具体实施方式Detailed ways

下面结合附图对本发明的控制方法作进一步详细的说明。The control method of the present invention will be described in further detail below in conjunction with the accompanying drawings.

所述内容中的系统电压，链接直流电压，换流器输出电流均由测量环节获得。在电气量信号用于实现控制目标时，已进行滤波处理和归算。The system voltage, link DC voltage, and converter output current in the content are all obtained by the measurement link. When the electrical quantity signal is used to achieve the control target, it has been filtered and reduced.

为了更清楚的阐述本发明的基于零序电压的换流链平均直流电压的控制方法的工作原理，现以级联H桥型STATCOM换流器系统为例进行分析说明，该STATCOM结构如附图1所示。每相由N个具有独立直流电容的级联型单相逆变器串联而成，三相换流链采用星型接法，中性点不接地。In order to more clearly explain the working principle of the method for controlling the average DC voltage of the converter chain based on the zero-sequence voltage of the present invention, the cascaded H-bridge STATCOM converter system is taken as an example for analysis and description. The STATCOM structure is shown in the accompanyingdrawing 1. Each phase is composed of N cascaded single-phase inverters with independent DC capacitors in series. The three-phase commutation chain adopts a star connection method, and the neutral point is not grounded.

附图2为本发明的基于零序电压的链式换流器平均直流电压控制方法整体示意图。该控制方法是：将三相换流链中A、B两相换流链的平均直流电压V_{dc_ave_a}、V_{dc_ave_b}与所有链节直流电压的平均值V_{dc_ave}相减得到的偏差量通过比例-积分调节器，可得到A、B两相换流链的有功功率偏差

有功功率偏差与测量所得的正序电流的有效值和相位I_p、φ_p经过零序电压指令运算环节，得到三相换流链的零序电压指令u_N；三相换流链的零序电压指令u_{N_a}，u_{N_b}，u_{N_c}均等于u_N/3，u_{N_a}，u_{N_b}，u_{N_c}作为换流链平均直流电压控制的三相调制波电压参考值控制换流器输出以实现闭环控制。图中，V_{dc_ave_a}、V_{dc_ave_b}、V_{dc_ave_c}分别为换流链ABC三相平均直流电压值，V_{dc_ave}为全局平均直流电压平均值，V_{dc_ave_a}、V_{dc_ave_b}、V_{dc_ave_c}由采样得到各相换流链单个链节的直流电压求平均值得到，V_{dc_ave}由所有链节的直流电压求平均值得到。Accompanying drawing 2 is the overall schematic diagram of the average DC voltage control method of the chain-link converter based on the zero-sequence voltage of the present invention. The control method is: in the three-phase commutation chain, the average DC voltage V_{dc_ave_a} and V_{dc_ave_b} of the two-phase commutation chain A and B in the three-phase commutation chain are subtracted from the average value V_{dc_ave} of the DC voltage of all links, and the deviation is obtained by proportional-integral Regulator, which can get the active power deviation of A and B two-phase commutation chains

Active power deviation The zero-sequence voltage command_{u N} of the three-phase commutation chain is obtained through the zero-sequence voltage command calculation link with the measured positive-sequence current effective value and phase I_p , φ_p ; the zero-sequence voltage command u of the three-phase commutation chain_{N_a} , u_{N_b} , u_{N_c} are all equal to u_N /3, u_{N_a} , u_{N_b} , u_{N_c} are used as the three-phase modulated wave voltage reference value of the average DC voltage control of the commutation chain to control the converter output to realize closed-loop control. In the figure, V_{dc_ave_a} , V_{dc_ave_b} , V_{dc_ave_c} are the average DC voltage values of the three phases of the commutation chain ABC respectively, V_{dc_ave} is the average value of the global average DC voltage, and V_{dc_ave_a} , V_{dc_ave_b} , V_{dc_ave_c} are obtained by sampling the commutation chains of each phase. The DC voltage of a single link is averaged, and V_{dc_ave} is obtained by the average of the DC voltages of all links.

图3给出了图2中零序电压指令运算环节的实现框图，具体实现方法如下：Figure 3 shows the implementation block diagram of the zero-sequence voltage command operation link in Figure 2, and the specific implementation method is as follows:

设定H桥型STATCOM换流器系统电压u_sA、u_sB、u_sC为：Set the H-bridge STATCOM converter system voltages u_sA , u_sB , u_sC as:

$\{\begin{matrix} {u u}_{sA sA} = = \sqrt{22} U u sin sin ((ωt ωt)) \\ {u u}_{sB sB} = = \sqrt{22} U u sin sin ((ωt ωt - - \frac{22 π π}{33})) \\ {u u}_{sC sC} = = \sqrt{22} U u sin sin ((ωt ωt + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 11))$

上式中，U为交流侧系统电压有效值，ω为基波角频率，t为时间。In the above formula, U is the effective value of the AC side system voltage, ω is the fundamental angular frequency, and t is time.

中性点电压u_n为：The neutral point voltage u_n is:

${u u}_{n no} = = \sqrt{22} {U u}_{N N} sin sin ((ωt ωt + + {φ φ}_{N N})) - - - - - - ((11 - - 22))$

上式中，U_N为中性点电压的有效值，φ_N为中性点电压的相位。由于换流器采用星型接线方式且中性点不接地，故零序电压完全叠加到中性点电压之上，即换流器中性点电压等于零序电压。In the above formula, U_N is the effective value of the neutral point voltage, and φ_N is the phase of the neutral point voltage. Since the converter adopts a star connection mode and the neutral point is not grounded, the zero-sequence voltage is completely superimposed on the neutral point voltage, that is, the neutral point voltage of the converter is equal to the zero-sequence voltage.

忽略负序分量干扰的条件下，假设流入换流器的电流i_A、i_B、i_C为：Under the condition of ignoring the interference of negative sequence components, it is assumed that the currents i_A , i_B , and i_C flowing into the converter are:

$\{\begin{matrix} {i i}_{A A} = = \sqrt{22} {I I}_{p p} sin sin ((ωt ωt + + {φ φ}_{p p})) \\ {i i}_{B B} = = \sqrt{22} {I I}_{p p} sin sin ((ωt ωt + + {φ φ}_{p p} - - \frac{22 π π}{33})) \\ {i i}_{C C} = = \sqrt{22} {I I}_{p p} sin sin ((ωt ωt + + {φ φ}_{p p} + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 33))$

上式中，I_p、φ_p为测量所得的正序电流的有效值和相位；In the above formula, I_p and φ_p are the effective value and phase of the measured positive sequence current;

输入换流器的有功功率为：The active power input to the converter is:

${P P}_{A A} = = \frac{11}{T T} {&Integral; &Integral;}_{00}^{T T} (({u u}_{sA sA} - - {u u}_{n no})) {i i}_{A A} dt dt - - - - - - ((11 - - 44))$

将式(1-1)～(1-3)代入式(1-4)得到A、B、C三相的有功功率、无功功率分别如(1-5)，(1-6)所示：Substitute equations (1-1)~(1-3) into equation (1-4) to get the active power and reactive power of the three phases A, B, and C, as shown in (1-5) and (1-6) respectively :

$\{\begin{matrix} {P P}_{A A} = = {UI UI}_{p p} cos cos (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n})) \\ {P P}_{B B} = = {UI UI}_{p p} cos cos (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n} - - \frac{22 π π}{33})) \\ {P P}_{C C} = = {UI UI}_{p p} cos cos (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n} + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 55))$

$(\begin{matrix} {Q Q}_{A A} = = U u {I I}_{p p} sin sin (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} sin sin (({φ φ}_{pN n})) \\ {Q Q}_{B B} = = U u {I I}_{p p} sin sin (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} sin sin (({φ φ}_{pN n} - - \frac{22 π π}{33})) \\ {Q Q}_{C C} = = U u {I I}_{p p} sin sin (({φ φ}_{p p})) - - {U u}_{N N} {I I}_{p p} sin sin (({φ φ}_{pN n} + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 66))$

式(1-5)和(1-6)中φ_pN为正序电流和零序电压的相位差。改变零序电压相位φ_N将导致φ_pN变化，故由式(1-5)和(1-6)可知，通过调节零序电压的大小和相位可以改变三相之间的功率分配。In formulas (1-5) and (1-6), φ_pN is the phase difference between positive sequence current and zero sequence voltage. Changing the phase φ_N of the zero-sequence voltage will lead to a change in φ_pN , so it can be seen from equations (1-5) and (1-6) that the power distribution among the three phases can be changed by adjusting the magnitude and phase of the zero-sequence voltage.

假设要维持三相直流电压平衡，三相换流器所需吸收的功率分别为

进一步表示为：Assuming that the three-phase DC voltage balance is to be maintained, the power absorbed by the three-phase converter is

Further expressed as:

$\{\begin{matrix} {P P}_{A A}^{* *} = = {P P}^{* *} - - Δ Δ {P P}_{A A}^{* *} \\ {P P}_{B B}^{* *} = = {P P}^{* *} - - Δ Δ {P P}_{B B}^{* *} \\ {P P}_{C C}^{* *} = = {P P}^{* *} - - Δ Δ {P P}_{C C}^{* *} \\ {Q Q}^{* *} = = (({Q Q}_{A A}^{* *} + + {Q Q}_{B B}^{* *} + + {Q Q}_{C C}^{* *})) / / 33 \\ {P P}^{* *} = = (({P P}_{A A}^{* *} + + {P P}_{B B}^{* *} + + {P P}_{C C}^{* *})) / / 33 \end{matrix} - - - - - - ((11 - - 77))$

式中，

为三相换流链的有功功率偏差，In the formula,

is the active power deviation of the three-phase commutation chain,

为了保证输出换流器输入和输出功率平衡，联立式(1-5)～(1-7)得到：In order to ensure the balance of the input and output power of the output converter, the parallel formulas (1-5)～(1-7) are obtained:

$\{\begin{matrix} {P P}^{* *} = = U u {I I}_{p p}^{* *} cos cos (({φ φ}_{p p}^{* *})) \\ {Q Q}^{* *} = = U u {I I}_{p p}^{* *} sin sin (({φ φ}_{p p}^{* *})) \end{matrix} - - - - - - ((11 - - 88))$

$\{\begin{matrix} {ΔP ΔP}_{A A}^{* *} = = {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n})) \\ Δ Δ {P P}_{B B}^{* *} = = {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n} - - \frac{22 π π}{33})) \\ {ΔP ΔP}_{C C}^{* *} = = {U u}_{N N} {I I}_{p p} cos cos (({φ φ}_{pN n} + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 99))$

通过式(1-8)可以确定

即通过有功、无功指令P^*、Q^*可以确定正序电流的有效值和相位指令

It can be determined by formula (1-8)

That is, the effective value and phase command of the positive sequence current can be determined through the active and reactive power commands P^* and Q^*

通过式(1-9)可以得到，只要根据任意两项电压偏差调节零序电压的幅值和相位，就可以保证第三相功率也满足要求，这个过程和正序电流的调节无关，也和第三相功率无关。因此该控制原则为只能调节两相，以下以AB两相调节为例。Through formula (1-9), it can be obtained that as long as the amplitude and phase of the zero sequence voltage are adjusted according to any two voltage deviations, the third phase power can also meet the requirements. This process has nothing to do with the adjustment of the positive sequence current, and it is also related to the first Three-phase power is irrelevant. Therefore, the control principle is that only two phases can be adjusted, and the following takes AB two-phase adjustment as an example.

将式(1-9)展开得到：Expand formula (1-9) to get:

${ΔP ΔP}_{A A}^{* *} = = {I I}_{p p} cos cos (({φ φ}_{p p})) {U u}_{N N} cos cos (({φ φ}_{N N})) + + {I I}_{p p} sin sin (({φ φ}_{p p})) {U u}_{N N} sin sin (({φ φ}_{N N})) - - - - - - ((11 - - 1010))$

根据瞬时无功理论：According to the instantaneous reactive power theory:

$\{\begin{matrix} {I I}_{d d} = = {I I}_{p p} cos cos (({φ φ}_{p p})) \\ {I I}_{q q} = = {I I}_{p p} sin sin (({φ φ}_{p p})) \end{matrix} - - - - - - ((11 - - 1111))$

上式中，I_d、I_q分别为正序电流的有功和无功分量，将式(1-11)代入式(1-10)得到A相换流链的有功功率偏差

In the above formula, I_d and I_q are the active and reactive components of the positive sequence current respectively, and substituting formula (1-11) into formula (1-10) to obtain the active power deviation of the A-phase commutation chain

$Δ Δ {P P}_{A A}^{* *} = = {I I}_{d d} {U u}_{N N} cos cos (({φ φ}_{N N})) + + {I I}_{q q} {U u}_{N N} sin sin (({φ φ}_{N N})) - - - - - - ((11 - - 1212))$

同理可以得到B相换流链的有功功率偏差

In the same way, the active power deviation of the B-phase commutation chain can be obtained

${ΔP ΔP}_{B B}^{* *} = = {U u}_{N N} cos cos (({φ φ}_{N N})) ((- - \frac{{I I}_{d d}}{22} + + \frac{\sqrt{33}}{22} {I I}_{q q})) - - {U u}_{N N} sin sin (({φ φ}_{N N})) ((\frac{\sqrt{33}}{22} {I I}_{d d} + + \frac{{I I}_{q q}}{22})) - - - - - - ((11 - - 1313))$

联立式(1-12)和式(1-13)得到两式中的U_Nsin(φ_N)、U_Ncos(φ_N)：Simultaneous formula (1-12) and formula (1-13) get U_N sin(φ_N ), U_N cos(φ_N ) in the two formulas:

$\{\begin{matrix} {U u}_{N N} sin sin (({φ φ}_{N N})) = = \frac{((\frac{{I I}_{d d}}{22} + + \frac{\sqrt{33}}{22} {I I}_{q q})) Δ Δ {P P}_{A A}^{* *} - - {ΔP ΔP}_{B B}^{* *} {I I}_{d d}}{\frac{\sqrt{33}}{22} (({I I}_{}^{q q} + + {I I}_{d d}^{22}))} \\ {U u}_{N N} cos cos (({φ φ}_{N N})) = = \frac{((\frac{\sqrt{33}}{22} {I I}_{d d} - - \frac{{I I}_{q q}}{22})) Δ Δ {P P}_{A A}^{* *} + + {I I}_{q q} Δ Δ {P P}_{B B}^{* *}}{\frac{\sqrt{33}}{22} (({I I}_{}^{q q} + + {I I}_{d d}^{22}))} \end{matrix} - - - - - - ((11 - - 1414))$

由于：because:

$\{\begin{matrix} ((\frac{\sqrt{33}}{22} {I I}_{d d} - - \frac{{I I}_{q q}}{22})) = = {I I}_{p p} ((sin sin ((\frac{22 π π}{33})) cos cos (({φ φ}_{p p})) + + cos cos ((\frac{22 π π}{33})) sin sin (({φ φ}_{p p})))) = = {I I}_{p p} sin sin (({φ φ}_{p p} + + \frac{22 π π}{33})) \\ ((\frac{{I I}_{d d}}{22} + + \frac{\sqrt{33}}{22} {I I}_{q q})) = = {I I}_{p p} ((cos cos ((\frac{π π}{33})) cos cos (({φ φ}_{p p})) + + sin sin ((\frac{π π}{33})) sin sin (({φ φ}_{p p})))) = = - - {I I}_{p p} cos cos (({φ φ}_{p p} + + \frac{22 π π}{33})) \end{matrix} - - - - - - ((11 - - 1515))$

将式(1-15)代入式(1-14)得到：Substitute formula (1-15) into formula (1-14) to get:

$\{\begin{matrix} {U u}_{N N} sin sin (({φ φ}_{N N})) = = \frac{- - Δ Δ {P P}_{A A}^{* *} cos cos (({φ φ}_{p p} + + \frac{22 π π}{33})) - - Δ Δ {P P}_{B B}^{* *} cos cos (({φ φ}_{p p}))}{\frac{\sqrt{33}}{22} {I I}_{p p}} \\ {U u}_{N N} cos cos (({φ φ}_{N N})) = = \frac{Δ Δ {P P}_{A A}^{* *} sin sin (({φ φ}_{p p} + + \frac{22 π π}{33})) + + {ΔP ΔP}_{B B}^{* *} sin sin (({φ φ}_{p p}))}{\frac{\sqrt{33}}{22} {I I}_{p p}} \end{matrix} - - - - - - ((11 - - 1616))$

由式(1-2)可得：From formula (1-2) can get:

u_N＝U_Nsin(ωt)cos(φ_N)+UNcos(ωt)sin(φ_N) (1-17)u_N ＝U_N sin(ωt)cos(φ_N )+UNcos(ωt)sin(φ_N ) (1-17)

将式(1-16)代入式(1-17)并化简得到：Substitute formula (1-16) into formula (1-17) and simplify to get:

${u u}_{N N} = = - - \frac{Δ Δ {P P}_{A A}^{* *}}{\frac{\sqrt{33}}{22} {I I}_{p p}} cos cos ((ωt ωt + + {φ φ}_{p p} + + \frac{22 π π}{33})) - - \frac{Δ Δ {P P}_{B B}^{* *}}{\frac{\sqrt{33}}{22} {I I}_{p p}} cos cos ((ωt ωt + + {φ φ}_{p p})) - - - - - - ((11 - - 1818))$

因此，根据式(1-18)得到换流器的零序电压，再经过乘法运算得到三相换流链的零序电压指令，该乘法运算是用换流器的零序电压u_N乘以1/3，所得值分别作为三相换流链的零序电压指令u_{N_a}，u_{N_b}，u_{N_c}；三相换流链的零序电压指令作为换流链平均直流电压控制的调制波电压参考值控制换三相流链输出构成闭环控制，从而实现控制换流链平均直流电压达到平衡。Therefore, the zero-sequence voltage of the converter is obtained according to formula (1-18), and then the zero-sequence voltage command of the three-phase commutation chain is obtained through multiplication. The multiplication is to multiply the zero-sequence voltage u_N of the converter by 1/3, the obtained values are respectively used as the zero-sequence voltage command u_{N_a} , u_{N_b} , u_{N_c} of the three-phase commutation chain; the zero-sequence voltage command of the three-phase commutation chain is used as the modulation wave voltage reference for the average DC voltage control of the commutation chain The value control commutates the output of the three-phase current chain to form a closed-loop control, so as to achieve the balance of the average DC voltage of the control commutation chain.

最后应该说明的是：以上实施例仅用以说明本发明的技术方案而非对其限制，结合上述实施例对本发明进行了详细说明，所属领域的普通技术人员应当理解到：本领域技术人员依然可以对本发明的具体实施方式进行修改或者等同替换，但这些修改或变更均在申请待批的权利要求保护范围之中。Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. The present invention has been described in detail in conjunction with the above embodiments, and those of ordinary skill in the art should understand that: Modifications or equivalent replacements can be made to the specific embodiments of the present invention, but these modifications or changes are within the protection scope of the pending claims.

Claims

1. control method based on the change of current chain mean direct voltage of residual voltage, it is characterized in that: this control method is that the mean direct voltage of any two-phase change of current chain and the mean value of all chain link direct voltages in all change of current chains are subtracted each other the mean direct voltage deviation that obtains two-phase change of current chain, through proportional-integral controller, obtain the active power deviation of corresponding phase change of current chain by the mean direct voltage deviation of two-phase change of current chain; The active power deviation obtains the residual voltage instruction of converter, and then obtains the residual voltage instruction of three-phase change of current chain by multiplying in conjunction with the effective value and the phase place process residual voltage ordering calculation link of the forward-order current of converter output; The residual voltage instruction of three-phase change of current chain is changed the output of three-phase stream chain as the modulating wave voltage reference value control of change of current chain mean direct voltage control and is constituted closed-loop control.

2. the control method of the change of current chain mean direct voltage based on residual voltage as claimed in claim 1, it is characterized in that: described residual voltage ordering calculation link is: will ask for the residual voltage instruction u of converter in the effective value of the forward-order current of active power deviation and converter output and the phase place substitution following formula_N, should instruct u again_NMean allocation obtains the residual voltage instruction of three-phase change of current chain in three-phase change of current chain:

u_{N} = - \frac{Δ P_{A}^{*}}{\frac{\sqrt{3}}{2} I_{p}} \cos (ωt + φ_{p} + \frac{2 π}{3}) - \frac{Δ P_{B}^{*}}{\frac{\sqrt{3}}{2} I_{p}} \cos (ωt + φ_{p})

In the formula,

Active power deviation for any two-phase change of current chain; I_p,

Be the effective value and the phase place of forward-order current, ω is the first-harmonic angular frequency, and t is the time.

3. the control method of the change of current chain mean direct voltage based on residual voltage as claimed in claim 1 is characterized in that: described multiplying is the residual voltage u with converter_NMultiply by 1/3, income value is respectively as the residual voltage of three-phase change of current chain instruction u_{N_a}, u_{N_b}, u_{N_c}, i.e. the residual voltage instruction u of three-phase change of current chain_{N_a}, u_{N_b}, u_{N_c}Equate.