CN105305841A

CN105305841A - General control method applicable to three-phase series VSC (Voltage Source Converter)

Info

Publication number: CN105305841A
Application number: CN201510672772.4A
Authority: CN
Inventors: 王春义; 曹增功; 梁甲文; 高峰; 郝全睿; 曹相阳
Original assignee: State Grid Corp of China SGCC; Liaocheng Power Supply Co of State Grid Shandong Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; Liaocheng Power Supply Co of State Grid Shandong Electric Power Co Ltd
Priority date: 2015-10-13
Filing date: 2015-10-13
Publication date: 2016-02-03

Abstract

本发明公开了一种适用于三相串联VSC的通用控制方法，该方法的核心是通过保证三个单相VSC的交流侧有功功率相等而实现三个串联的单相VSC直流侧电压平衡。本发明考虑换流器变压器的接线方式，可以利用交流故障下三种不同的电流控制方案来实现不同的控制目标，本发明使三相串联VSC具备了良好的交流故障穿越能力，实现了三相串联VSC的安全稳定运行，使其工业应用成为可能。The invention discloses a general control method suitable for three-phase series VSCs. The core of the method is to realize the DC side voltage balance of three series single-phase VSCs by ensuring that the active powers of the three single-phase VSCs are equal. The invention considers the connection mode of the converter transformer, and can use three different current control schemes under AC faults to achieve different control objectives. The safe and stable operation of series VSC makes its industrial application possible.

Description

A general control method suitable for three-phase series VSC

技术领域 technical field

本发明涉及一种适用于三相串联VSC的通用控制方法，属于电力电子装置控制技术领域。 The invention relates to a general control method applicable to a three-phase series VSC, belonging to the technical field of power electronic device control.

背景技术 Background technique

电压源型换流器(VoltageSourceConverter,VSC)具有有功无功独立调节、可向无源网络供电、潮流反转无需改变电压极性等优点，特别适合作为直流电网中的落点换流器。 Voltage Source Converter (Voltage Source Converter, VSC) has the advantages of independent adjustment of active and reactive power, power supply to passive network, and no need to change voltage polarity for power flow reversal. It is especially suitable as a drop-point converter in DC grid.

通用的三相串联电压源型换流器(VoltageSourceConverter,VSC)的拓扑结构如图1所示，其将三个单相VSC在直流侧串联，每个单相VSC的交流端与一个单相变压器的二次侧相连，三个单相变压器的一次侧采用角形连接。理论上，任意拓扑结构的单相VSC都可以在直流侧串联组成三相串联VSC，不同拓扑结构的单相VSC对应不同的三相串联VSC，图2-5为四种常见的不同拓扑结构的单相VSC。 The topology of a general three-phase series voltage source converter (Voltage Source Converter, VSC) is shown in Figure 1, which connects three single-phase VSCs in series on the DC side, and the AC end of each single-phase VSC is connected to a single-phase transformer The secondary sides of the three single-phase transformers are connected in a delta connection. Theoretically, single-phase VSCs of any topological structure can be connected in series on the DC side to form a three-phase series VSC. Single-phase VSCs of different topological structures correspond to different three-phase series VSCs. Figure 2-5 shows four common topological structures. Single-phase VSCs.

三相串联VSC控制的难点在于如何实现其在交流故障下的安全稳定运行。正常工作时，三个单相VSC在直流侧串联来承受整个直流电压，每个单相VSC承受三分之一的直流电压，开关元器件也按照承受三分之一的直流电压整定。发生交流故障时，三个串联的单相VSC必须保持各单相直流侧电压恒定，否则，开关元器件有被击穿的危险。 The difficulty of three-phase series VSC control lies in how to realize its safe and stable operation under AC fault. During normal operation, three single-phase VSCs are connected in series on the DC side to withstand the entire DC voltage, each single-phase VSC withstands one-third of the DC voltage, and the switching components are also set to withstand one-third of the DC voltage. When an AC fault occurs, three single-phase VSCs in series must keep the voltage of each single-phase DC side constant, otherwise, the switching components may be broken down.

中国专利文献CN102170243A公开了一种基于负序电流的换流链平均直流电压的控制方法，将三相换流链中任意两相的平均直流电压与所有链节的直流电压平均值相比较得到两相换流链的平均直流电压偏差，经比例积分调节器得到对应相换流链的有功功率偏差；有功功率偏差结合交流侧系统电压有效值经负序电流指令运算环节，得到三相换流链的负序电流分量指令；经派克变换环节将三相负序电流分量指令变换为负序电流指令的dq轴分量；然后通过负序电流解耦控制环节得到负序调制波电压的dq轴分量，随后进行派克反变换得到三相负序调制波电压参考值，控制变流器输出构成闭环控制。但是，该专利存在以下缺陷：(1)仅利用了负序电流；(2)仅能实现直流电压平衡；(3)仅适用于链式H桥型换流器。 Chinese patent document CN102170243A discloses a method for controlling the average DC voltage of a commutation chain based on negative sequence current. The average DC voltage of any two phases in a three-phase commutation chain is compared with the average value of DC voltages of all links to obtain two The average DC voltage deviation of the phase commutation chain is obtained through the proportional integral regulator to obtain the active power deviation of the corresponding phase commutation chain; the active power deviation is combined with the effective value of the AC side system voltage through the negative sequence current command operation link to obtain the three-phase commutation chain The negative sequence current component command of the negative sequence current component; the three-phase negative sequence current component command is transformed into the dq axis component of the negative sequence current command through the Parker transformation link; then the dq axis component of the negative sequence modulation wave voltage is obtained through the negative sequence current decoupling control link, Subsequently, Parker inverse transformation is performed to obtain the reference value of the three-phase negative-sequence modulation wave voltage, and the output of the converter is controlled to form a closed-loop control. However, this patent has the following defects: (1) it only utilizes negative sequence current; (2) it can only realize DC voltage balance; (3) it is only applicable to chained H-bridge converters.

发明内容 Contents of the invention

针对现有技术的不足，本发明提供了一种适用于三相串联VSC的通用控制方法； Aiming at the deficiencies of the prior art, the present invention provides a general control method suitable for three-phase series VSC;

本发明的核心是通过保证三个单相VSC的交流侧有功功率相等进而实现三个串联的单相VSC直流侧电压平衡。 The core of the present invention is to realize the DC side voltage balance of three single-phase VSCs connected in series by ensuring that the active powers of the AC sides of the three single-phase VSCs are equal.

本发明利用了零序电流及负序电流；本发明除了实现直流链电压平衡，还可以实现交流电流三项对称、或消除有功功率二次波动、或消除无功功率二次波动；本发明还可以适用于半H桥型换流器。 The present invention utilizes the zero-sequence current and the negative-sequence current; in addition to realizing DC link voltage balance, the present invention can also realize the trinomial symmetry of AC current, or eliminate the secondary fluctuation of active power, or eliminate the secondary fluctuation of reactive power; the present invention also It can be applied to half H-bridge converters.

本发明的技术方案为： Technical scheme of the present invention is:

一种适用于三相串联VSC的通用控制方法，所述三相串联VSC包括：在直流侧串联的三个单相VSC，每个单相VSC的交流端与一个单相变压器的二次侧相连，三个单相变压器的一次侧采用角形连接，具体步骤包括： A general control method applicable to a three-phase series VSC, the three-phase series VSC comprising: three single-phase VSCs connected in series on the DC side, and the AC end of each single-phase VSC is connected to the secondary side of a single-phase transformer , the primary sides of the three single-phase transformers are connected in an angle, and the specific steps include:

(1)分别求取三个单相变压器的二次侧电压和二次侧电流： (1) Calculate the secondary side voltage and secondary side current of the three single-phase transformers respectively:

三个单相变压器的二次侧电压的求取公式分别为： The formulas for obtaining the secondary side voltages of the three single-phase transformers are:

式(Ⅰ)-式(Ⅲ)中，u_a、u_b、u_c分别为三个单相变压器二次侧A、B、C相的交流电压；U⁺为正序电压的幅值，U^-为负序电压的幅值，为正序电压的初始相角，为负序电压的初始相角，θ＝ωt，ω为电网电压的角频率，t为时间； In formula (Ⅰ)-formula (Ⅲ), u _a , u _b , u _c are the AC voltages of phases A, B, and C on the secondary side of the three single-phase transformers respectively; U ⁺ is the amplitude of the positive sequence voltage, and U ^- is the magnitude of the negative sequence voltage, is the initial phase angle of the positive sequence voltage, is the initial phase angle of the negative sequence voltage, θ=ωt, ω is the angular frequency of the grid voltage, and t is time;

三个单相变压器的二次侧电流的求取公式分别为： The formulas for obtaining the secondary side currents of the three single-phase transformers are:

式(Ⅳ)-式(Ⅵ)中，i_a、i_b、i_c分别为三个单相变压器二次侧A、B、C相的交流电流；I⁺为正序电流的幅值，I^-为负序电流的幅值，I⁰为零序电流的幅值，为正序电流的初始相角，为负序电流的初始相角，为零序电流的初始相角； Formula (Ⅳ)-In formula (Ⅵ), i _a , i _b , i _c are the AC currents of phases A, B, and C of the secondary sides of the three single-phase transformers respectively; I ⁺ is the amplitude of the positive sequence current, and I ^- is the magnitude of the negative sequence current, I ⁰ is the magnitude of the zero sequence current, is the initial phase angle of the positive sequence current, is the initial phase angle of the negative sequence current, is the initial phase angle of the zero-sequence current;

(2)交流电压不平衡时，换流器的瞬时有功功率和瞬时无功功率表示为： (2) When the AC voltage is unbalanced, the instantaneous active power and instantaneous reactive power of the converter are expressed as:

p(t)＝u_ai_a+u_bi_b+u_ci_c＝P₀+P_c2cos(2ωt)+P_s2sin(2ωt)(Ⅶ) p(t)＝u _a i _a +u _b i _b +u _c i _c ＝P ₀ +P _c2 cos(2ωt)+P _s2 sin(2ωt)(VII)

$q q ((t t)) = = \frac{11}{\sqrt{33}} (({u u}_{a a b b} {i i}_{c c} + + {u u}_{b b c c} {i i}_{a a} + + {u u}_{c c a a} {i i}_{b b})) = = {Q Q}_{00} + + {Q Q}_{c c 22} c c o o s the s ((22 ω ω t t)) + + {Q Q}_{s the s 22} s the s i i n no ((22 ω ω t t)) - - - - - - ((V V I I I I I I))$

式(Ⅶ)-式(Ⅷ)中，p(t)为三相串联VSC总的瞬时有功功率，q(t)为三相串联VSC总的瞬时无功功率，P₀为三相串联VSC瞬时有功功率的平均值，Q₀为三相串联VSC瞬时无功功率的平均值，P_c2、P_s2分别为瞬时有功功率因交流电压不对称产生的二次波动，Q_c2、Q_s2分别为瞬时无功功率因交流电压不对称产生的二次波动，u_ab＝u_a-u_b，u_bc＝u_b-u_c，u_ca＝u_c-u_a； In formula (Ⅶ)-(Ⅷ), p(t) is the total instantaneous active power of three-phase series VSC, q(t) is the total instantaneous reactive power of three-phase series series VSC, P ₀ is the instantaneous power of three-phase series series VSC The average value of the active power, Q ₀ is the average value of the instantaneous reactive power of the three-phase series VSC, P _c2 and P _s2 are the secondary fluctuations of the instantaneous active power due to the asymmetry of the AC voltage, and Q _c2 and Q _s2 are the instantaneous Secondary fluctuation of reactive power due to AC voltage asymmetry, u _ab = u _a -u _b , u _bc = u _b -u _c , u _ca = u _c -u _a ;

根据式(Ⅰ)-式(Ⅷ)推导三相串联VSC的各功率分量的表达式： The expressions of each power component of the three-phase series VSC are deduced according to the formula (Ⅰ)-(Ⅷ):

式(Ⅸ)-式(Ⅺ)中，P_a、P_b、P_c分别为三相串联VSC的A、B、C相的瞬时有功功率平均值； Equation (IX)-In Equation (XI), P _a , P _b , and P _c are the average instantaneous active power of phases A, B, and C of the three-phase series VSC, respectively;

(3)广义同步旋转坐标系下各正序、负序和零序分量为： (3) The positive sequence, negative sequence and zero sequence components in the generalized synchronous rotating coordinate system are:

式(XVIII)中，均为直流量，为正序电压的d轴分量，为正序电压的q轴分量，为负序电压的d轴分量，为负序电压的q轴分量，为正序电流的d轴分量，为正序电流的q轴分量，为负序电流的d轴分量，为负序电流的q轴分量，为零序电流的d轴分量，为零序电流的q轴分量； In formula (XVIII), are direct flow, is the d-axis component of the positive sequence voltage, is the q-axis component of the positive sequence voltage, is the d-axis component of the negative sequence voltage, is the q-axis component of the negative sequence voltage, is the d-axis component of the positive sequence current, is the q-axis component of the positive sequence current, is the d-axis component of the negative sequence current, is the q-axis component of the negative sequence current, is the d-axis component of the zero-sequence current, is the q-axis component of the zero-sequence current;

根据式(XVIII)、式(Ⅻ)和式(XIII)，推导出表达式(XIX)和式(XX)： According to formula (XVIII), formula (XII) and formula (XIII), deduce expression (XIX) and formula (XX):

${P P}_{00} = = \frac{33}{22} (({u u}_{d d}^{+ +} {i i}_{d d}^{+ +} + + {u u}_{q q}^{+ +} {i i}_{q q}^{+ +} + + {u u}_{d d}^{- -} {i i}_{d d}^{- -} + + {u u}_{q q}^{- -} {i i}_{q q}^{- -})) - - - - - - ((X x I I X x))$

${Q Q}_{00} = = \frac{33}{22} (({u u}_{q q}^{+ +} {i i}_{d d}^{+ +} - - {u u}_{d d}^{+ +} {i i}_{q q}^{+ +} + + {u u}_{q q}^{- -} {i i}_{d d}^{- -} - - {u u}_{d d}^{- -} {i i}_{q q}^{- -})) - - - - - - ((X x X x))$

根据式(XIX)和(XX)，各电压分量已知的情况下，推导出表达式(XXI)和式(XXII)： According to formulas (XIX) and (XX), each voltage component Under known circumstances, deduce expression (XXI) and formula (XXII):

${P P}_{00}^{* *} = = \frac{33}{22} (({u u}_{d d}^{+ +} {i i}_{d d}^{+ + * *} + + {u u}_{q q}^{+ +} {i i}_{q q}^{+ + * *} + + {u u}_{d d}^{- -} {i i}_{d d}^{- - * *} + + {u u}_{q q}^{- -} {i i}_{q q}^{- - * *})) - - - - - - ((X x X x I I))$

${Q Q}_{00}^{* *} = = \frac{33}{22} (({u u}_{q q}^{+ +} {i i}_{d d}^{+ + * *} - - {u u}_{d d}^{+ +} {i i}_{q q}^{+ + * *} + + {u u}_{q q}^{- -} {i i}_{d d}^{- - * *} - - {u u}_{d d}^{- -} {i i}_{q q}^{- - * *})) - - - - - - ((X x X x I I I I))$

式(XXI)和式(XXII)中，为瞬时有功功率平均值的参考值，为瞬时无功功率平均值的参考值，分别为的参考值； In formula (XXI) and formula (XXII), is the reference value of the average value of instantaneous active power, is the reference value of instantaneous reactive power average value, respectively the reference value;

(4)由P_a＝P₀/3、P_b＝P₀/3和式(XVIII)推导得出相间功率平衡条件，即表达式(XXIII)及式(XXIV)： (4) From P _a ＝P ₀ /3, P _b ＝P ₀ /3 and formula (XVIII), the phase-to-phase power balance condition is derived, that is, expression (XXIII) and formula (XXIV):

${u u}_{d d}^{- -} {i i}_{d d}^{+ +} - - {u u}_{q q}^{- -} {i i}_{q q}^{+ +} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- -} - - {u u}_{q q}^{+ +} {i i}_{q q}^{- -} + + (({u u}_{d d}^{+ +} + + {u u}_{d d}^{- -})) {i i}_{d d}^{00} + + (({u u}_{q q}^{+ +} - - {u u}_{q q}^{- -})) {i i}_{q q}^{00} = = 00 - - - - - - ((X x X x I I I I I I))$

$\begin{matrix} ((- - {u u}_{d d}^{- -} - - \sqrt{33} {u u}_{q q}^{- -})) {i i}_{d d}^{+ +} + + (({u u}_{q q}^{- -} - - \sqrt{33} {u u}_{d d}^{- -})) {i i}_{q q}^{+ +} - - (({u u}_{d d}^{+ +} + + \sqrt{33} {u u}_{q q}^{+ +})) {i i}_{d d}^{- -} + + (({u u}_{q q}^{+ +} - - \sqrt{33} {u u}_{d d}^{+ +})) {i i}_{q q}^{- -} \\ + + ((- - {u u}_{d d}^{+ +} + + \sqrt{33} {u u}_{q q}^{+ +} - - {u u}_{d d}^{- -} + + \sqrt{33} {u u}_{q q}^{- -})) {i i}_{d d}^{00} + + ((- - {u u}_{q q}^{+ +} - - \sqrt{33} {u u}_{d d}^{+ +} + + {u u}_{q q}^{- -} + + \sqrt{33} {u u}_{d d}^{- -})) {i i}_{q q}^{00} = = 00 \end{matrix} - - - - - - ((X x X x I I V V))$

本发明的核心是通过保证三个单相VSC的交流侧有功功率相等进而实现三个串联的单相VSC直流侧电压平衡。 The core of the invention is to realize the DC side voltage balance of three single-phase VSCs connected in series by ensuring that the active powers of the AC sides of the three single-phase VSCs are equal.

因为三个串联单相VSC流过同一直流电流，如果三个单相VSC的直流侧电压相等，则每个单相VSC的直流功率也相同。忽略开关元器件的损耗，每个单相VSC输出的直流功率平均值等于其交流侧的有功功率平均值。因此，为了维持单相VSC直流侧电压相等，只需要保证三个单相VSC的交流侧有功功率平均值相同，即P_a＝P_b＝P_c＝P₀/3。 Because the same DC current flows through the three single-phase VSCs in series, if the DC side voltages of the three single-phase VSCs are equal, the DC power of each single-phase VSC is also the same. Neglecting the loss of switching components, the average value of DC power output by each single-phase VSC is equal to the average value of active power on its AC side. Therefore, in order to keep the DC side voltages of the single-phase VSCs equal, it is only necessary to ensure that the average active power values of the AC sides of the three single-phase VSCs are the same, that is, P _a =P _b =P _c =P ₀ /3.

根据式(XXIII)和(XXIV)，各电压分量已知的情况下，推导出表达式(XXV)和式(XXVI)： According to formulas (XXIII) and (XXIV), each voltage component Under known circumstances, deduce expression (XXV) and formula (XXVI):

${u u}_{d d}^{- -} {i i}_{d d}^{+ + * *} - - {u u}_{q q}^{- -} {i i}_{q q}^{+ + * *} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- - * *} - - {u u}_{q q}^{+ +} {i i}_{q q}^{- - * *} + + (({u u}_{d d}^{+ +} + + {u u}_{d d}^{- -})) {i i}_{d d}^{00 * *} + + (({u u}_{q q}^{+ +} - - {u u}_{q q}^{- -})) {i i}_{q q}^{00 * *} = = 00 - - - - - - ((X x X x V V))$

$\begin{matrix} ((- - {u u}_{d d}^{- -} - - \sqrt{33} {u u}_{q q}^{- -})) {i i}_{d d}^{+ + * *} + + (({u u}_{q q}^{- -} - - \sqrt{33} {u u}_{d d}^{- -})) {i i}_{q q}^{+ + * *} - - (({u u}_{d d}^{+ +} + + \sqrt{33} {u u}_{q q}^{+ +})) {i i}_{d d}^{- - * *} + + (({u u}_{q q}^{+ +} - - \sqrt{33} {u u}_{d d}^{+ +})) {i i}_{q q}^{- - * *} \\ + + ((- - {u u}_{d d}^{+ +} + + \sqrt{33} {u u}_{q q}^{+ +} - - {u u}_{d d}^{- -} + + \sqrt{33} {u u}_{q q}^{- -})) {i i}_{d d}^{00 * *} + + ((- - {u u}_{q q}^{+ +} - - \sqrt{33} {u u}_{d d}^{+ +} + + {u u}_{q q}^{- -} + + \sqrt{33} {u u}_{d d}^{- -})) {i i}_{q q}^{00 * *} = = 00 \end{matrix} - - - - - - ((X x X x V V I I))$

式(XXV)和式(XXVI)中，分别为的参考值； In formula (XXV) and formula (XXVI), respectively the reference value;

(5)消除瞬时有功功率的二次波动，即P_c2＝0、P_s2＝0，由式(XIV)和(XV)推导出表达式(XXVII)及表达式(XXVIII)： (5) Eliminate the secondary fluctuation of instantaneous active power, that is, P _c2 = 0, P _s2 = 0, deduce expression (XXVII) and expression (XXVIII) from formula (XIV) and (XV):

${u u}_{d d}^{- -} {i i}_{d d}^{+ +} + + {u u}_{q q}^{- -} {i i}_{q q}^{+ +} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- -} + + {u u}_{q q}^{+ +} {i i}_{q q}^{- -} = = 00 - - - - - - ((X x X x V V I I I I))$

${u u}_{q q}^{- -} {i i}_{d d}^{+ +} - - {u u}_{d d}^{- -} {i i}_{q q}^{+ +} - - {u u}_{q q}^{+ +} {i i}_{d d}^{- -} + + {u u}_{d d}^{+ +} {i i}_{q q}^{- -} = = 00 - - - - - - ((X x X x V V I I I I I I))$

根据式(XXVII)和(XXVIII)，各电压分量已知的情况下，推导出表达式(XXIX)和式(XXX)： According to formulas (XXVII) and (XXVIII), each voltage component Under known circumstances, deduce expression (XXIX) and formula (XXX):

${u u}_{d d}^{- -} {i i}_{d d}^{+ + * *} + + {u u}_{q q}^{- -} {i i}_{q q}^{+ + * *} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- - * *} + + {u u}_{q q}^{+ +} {i i}_{q q}^{- - * *} = = 00 - - - - - - ((X x X x I I X x))$

${u u}_{q q}^{- -} {i i}_{d d}^{+ + * *} - - {u u}_{d d}^{- -} {i i}_{q q}^{+ + * *} - - {u u}_{q q}^{+ +} {i i}_{d d}^{- - * *} + + {u u}_{d d}^{+ +} {i i}_{q q}^{- - * *} = = 00 - - - - - - ((X x X x X x))$

(6)消除瞬时无功功率的二次波动，即Q_c2＝0、Q_s2＝0，由式(XVI)和(XVII)推导出表达式(XXXI)及表达式(XXXII)： (6) Eliminate the secondary fluctuation of instantaneous reactive power, that is, Q _c2 = 0, Q _s2 = 0, deduce expression (XXXI) and expression (XXXII) from formula (XVI) and (XVII):

$- - {u u}_{d d}^{- -} {i i}_{q q}^{+ +} + + {u u}_{q q}^{- -} {i i}_{d d}^{+ +} - - {u u}_{d d}^{+ +} {i i}_{q q}^{- -} + + {u u}_{q q}^{+ +} {i i}_{d d}^{- -} = = 00 - - - - - - ((X x X x X x I I))$

$- - {u u}_{q q}^{- -} {i i}_{q q}^{+ +} - - {u u}_{d d}^{- -} {i i}_{d d}^{+ +} + + {u u}_{q q}^{+ +} {i i}_{q q}^{- -} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- -} = = 00 - - - - - - ((X x X x X x I I I I))$

根据式(XXXI)和(XXXII)，各电压分量已知的情况下，推导出表达式(XXXIII)和式(XXXIV)： According to formulas (XXXI) and (XXXII), each voltage component Under known circumstances, deduce expression (XXXIII) and formula (XXXIV):

$- - {u u}_{d d}^{- -} {i i}_{q q}^{+ + * *} + + {u u}_{q q}^{- -} {i i}_{d d}^{+ + * *} - - {u u}_{d d}^{+ +} {i i}_{q q}^{- - * *} + + {u u}_{q q}^{+ +} {i i}_{d d}^{- - * *} = = 00 - - - - - - ((X x X x X x I I I I I I))$

$- - {u u}_{q q}^{- -} {i i}_{q q}^{+ + * *} - - {u u}_{d d}^{- -} {i i}_{d d}^{+ + * *} + + {u u}_{q q}^{+ +} {i i}_{q q}^{- - * *} + + {u u}_{d d}^{+ +} {i i}_{d d}^{- - * *} = = 00 - - - - - - ((X x X x X x I I V V))$

(7)根据具体的控制目标，确定并求取单相变压器二次侧电流分量： (7) According to the specific control target, determine and obtain the current component of the secondary side of the single-phase transformer:

a、如需保证电网交流电流三相对称，单相变压器二次侧电流分量包括式(XXI)、式(XXII)、式(XXV)和式(XXVI)组成方程组，同时求解单相变压器二次侧电流分量的参考值 a. If it is necessary to ensure the three-phase symmetry of the AC current of the grid, the current components of the secondary side of the single-phase transformer include Formula (XXI), formula (XXII), formula (XXV) and formula (XXVI) form equation system, simultaneously Solving the Secondary Current Components of a Single-Phase Transformer reference value

b、如需消除交流侧有功功率二次波动，单相变压器二次侧电流分量包括式(XXI)、式(XXII)、式(XXV)、式(XXVI)、式(XXIX)和(XXX)组成方程组，求解单相变压器二次侧电流分量的参考值 $i_{d}^{+ *}, i_{q}^{+ *}, i_{d}^{- *}, i_{q}^{- *}, i_{d}^{0 *}, i_{q}^{0 *};$ b. If it is necessary to eliminate the secondary fluctuation of active power on the AC side, the current component of the secondary side of the single-phase transformer includes Equation (XXI), Equation (XXII), Equation (XXV), Equation (XXVI), Equation (XXIX) and (XXX) form a system of equations to solve the current component of the secondary side of the single-phase transformer reference value $i_{d}^{+ *}, i_{q}^{+ *}, i_{d}^{- *}, i_{q}^{- *}, i_{d}^{0 *}, i_{q}^{0 *};$

c、如需消除交流侧无功功率二次波动，单相变压器二次侧电流分量包括式(XXI)、式(XXII)、式(XXV)、式(XXVI)、式(XXXIII和(XXXIV)组成方程组，求解单相变压器二次侧电流分量的参考值 $i_{d}^{+ *}, i_{q}^{+ *}, i_{d}^{- *}, i_{q}^{- *}, i_{d}^{0 *}, i_{q}^{0 *};$ c. If it is necessary to eliminate the secondary fluctuation of reactive power on the AC side, the current component of the secondary side of the single-phase transformer includes Equation (XXI), Equation (XXII), Equation (XXV), Equation (XXVI), Equation (XXXIII and (XXXIV) form a system of equations to solve the current component of the secondary side of the single-phase transformer reference value $i_{d}^{+ *}, i_{q}^{+ *}, i_{d}^{- *}, i_{q}^{- *}, i_{d}^{0 *}, i_{q}^{0 *};$

(8)在得到各电流分量参考值的基础上，通过广义同步坐标系下的基于比例积分控制器的电流内环控制实现对三相串联VSC电流的快速调制。 (8) On the basis of obtaining the reference value of each current component, the rapid modulation of the three-phase series VSC current is realized through the current inner loop control based on the proportional-integral controller in the generalized synchronous coordinate system.

根据本发明优选的，输入u_a、u_b、u_c，通过对称分量检测，输出得到输入i_a、i_b、i_c，通过对称分量检测，输出得到 Preferably, according to the present invention, input u _a , _ub , _uc , through symmetrical component detection, the output is obtained Input i _a , i _b , i _c , through symmetrical component detection, the output is obtained

根据本发明优选的，通过定功率控制实现所述步骤(7)。 Preferably according to the present invention, the step (7) is realized by constant power control.

根据本发明优选的，所述通过广义同步坐标系下的基于比例积分控制器的电流内环控制实现对三相串联VSC电流的快速调制，具体步骤包括： Preferably according to the present invention, the rapid modulation of the three-phase series VSC current is realized through the current inner loop control based on the proportional-integral controller under the generalized synchronous coordinate system, and the specific steps include:

A、由对应的内环电流控制器分别得到：的参考值的参考值的参考值通过调节实现对的快速控制； A. Obtained from the corresponding inner loop current controller: reference value reference value reference value by regulating to achieve quick control of

B、经过Clarke变换，静止a-b-c坐标系下的相加得到参考电压 $u_{a}^{*}, u_{b}^{*}, u_{c}^{*} .$ B. After Clarke transformation, the static abc coordinate system Add up to get the reference voltage $u_{a}^{*}, u_{b}^{*}, u_{c}^{*} .$

本发明的有益效果为： The beneficial effects of the present invention are:

本发明提出了适用于三相串联VSC的通用控制方法，使三相串联VSC换流器具备了良好的交流故障穿越能力，实现了三相串联VSC的安全稳定运行，使其工业应用成为可能。 The invention proposes a general control method suitable for three-phase series VSC, which enables the three-phase series VSC converter to have good AC fault ride-through capability, realizes the safe and stable operation of the three-phase series VSC, and makes its industrial application possible.

附图说明 Description of drawings

图1为通用的三相串联VSC的结构示意图； Figure 1 is a schematic structural diagram of a general three-phase series VSC;

图2为半H桥两电平拓扑结构的单相VSC的示意图； 2 is a schematic diagram of a single-phase VSC with a half-H bridge two-level topology;

图3为H桥塑形拓扑结构的单相VSC的示意图； 3 is a schematic diagram of a single-phase VSC with an H-bridge shaping topology;

图4为半H桥MMC拓扑结构的单相VSC的示意图； Fig. 4 is the schematic diagram of the single-phase VSC of half H bridge MMC topological structure;

图5为H桥MMC拓扑结构的单相VSC的示意图； Fig. 5 is the schematic diagram of the single-phase VSC of H bridge MMC topological structure;

图6为本发明所述适用于三相串联VSC的通用控制方法的流程图； 6 is a flow chart of a general control method applicable to a three-phase series VSC according to the present invention;

图7为本发明所述适用于三相串联VSC的通用控制方法的控制框图。 FIG. 7 is a control block diagram of a general control method applicable to a three-phase series VSC according to the present invention.

具体实施方式 detailed description

下面结合说明书附图和实施例对本发明作进一步限定，但不限于此。 The present invention will be further limited below in conjunction with the accompanying drawings and embodiments, but not limited thereto.

实施例 Example

一种适用于三相串联VSC的通用控制方法，如图6所示，所述三相串联VSC包括：在直流侧串联的三个单相VSC，每个单相VSC的交流端与一个单相变压器的二次侧相连，三个单相变压器的一次侧采用角形连接，具体步骤包括： A general control method suitable for a three-phase series VSC, as shown in Figure 6, the three-phase series VSC includes: three single-phase VSCs connected in series on the DC side, the AC end of each single-phase VSC is connected to a single-phase The secondary sides of the transformers are connected, and the primary sides of the three single-phase transformers are connected in an angle shape. The specific steps include:

根据式(Ⅰ)-式(Ⅷ)推导三相串联VSC的各功率分量的表达式： The expressions of each power component of the three-phase series VSC are deduced according to formula (Ⅰ)-(Ⅷ):

(8)在得到各电流分量参考值的基础上，通过广义同步坐标系下的基于比例积分控制器的电流内环控制实现对三相串联VSC电流的快速调制。 (8) On the basis of obtaining the reference values of each current component, the rapid modulation of the three-phase series VSC current is realized through the current inner loop control based on the proportional-integral controller in the generalized synchronous coordinate system.

输入u_a、u_b、u_c，通过对称分量检测，输出得到输入i_a、i_b、i_c，通过对称分量检测，输出得到 Input u _a , u _b , u _c , through symmetrical component detection, the output is Input i _a , i _b , i _c , through symmetrical component detection, the output is obtained

通过定功率控制实现所述步骤(7)。 The step (7) is realized by constant power control.

所述通过广义同步坐标系下的基于比例积分控制器的电流内环控制实现对三相串联VSC电流的快速调制，具体步骤包括： The rapid modulation of the three-phase series VSC current is realized through the current inner loop control based on the proportional-integral controller under the generalized synchronous coordinate system, and the specific steps include:

所述适用于三相串联VSC的通用控制方法的控制框图如图7所示。 The control block diagram of the general control method applicable to the three-phase series VSC is shown in FIG. 7 .

Claims

1. one kind is applicable to the universal control method of three-phase series VSC, described three-phase series VSC comprises: at three single-phase VSC of DC side series connection, the interchange end of each single-phase VSC is connected with the secondary side of a single-phase transformer, the primary side of three single-phase transformers adopts Angle connection, it is characterized in that, concrete steps comprise:

(1) secondary side voltage and the secondary side current of three single-phase transformers is asked for respectively:

The formula of asking for of the secondary side voltage of three single-phase transformers is respectively:

In formula (I)-Shi (III), u _a, u _b, u _cbe respectively the alternating voltage of three single-phase transformer secondary side A, B, C phases; U ⁺for the amplitude of positive sequence voltage, U ^-for the amplitude of negative sequence voltage, for the initial phase angle of positive sequence voltage, for the initial phase angle of negative sequence voltage, θ=ω t, ω are the angular frequency of line voltage, and t is the time;

The formula of asking for of the secondary side current of three single-phase transformers is respectively:

In formula (IV)-Shi (VI), i _a, i _b, i _cbe respectively the alternating current of three single-phase transformer secondary side A, B, C phases; I ⁺for the amplitude of forward-order current, I ^-for the amplitude of negative-sequence current, I ⁰for the amplitude of zero-sequence current, for the initial phase angle of forward-order current, for the initial phase angle of negative-sequence current, for the initial phase angle of zero-sequence current;

(2), when alternating voltage is uneven, instantaneous active power and the instantaneous reactive power of converter are expressed as:

p(t)＝u _ai _a+u _bi _b+u _ci _c＝P ₀+P _c2cos(2ωt)+P _s2sin(2ωt)(Ⅶ)

q (t) = \frac{1}{\sqrt{3}} (u_{a b} i_{c} + u_{b c} i_{a} + u_{c a} i_{b}) = Q_{0} + Q_{c 2} c o s (2 ω t) + Q_{s 2} s i n (2 ω t) - - - (V I I I)

In formula (VII)-Shi (VIII), p (t) is the total instantaneous active power of three-phase series VSC, and q (t) is the total instantaneous reactive power of three-phase series VSC, P ₀for the mean value of three-phase series VSC instantaneous active power, Q ₀for the mean value of three-phase series VSC instantaneous reactive power, P _c2, P _s2being respectively instantaneous active power because of the secondary of the asymmetric generation of alternating voltage fluctuates, Q _c2, Q _s2being respectively instantaneous reactive power because of the secondary of the asymmetric generation of alternating voltage fluctuates, u _ab=u _a-u _b, u _bc=u _b-u _c, u _ca=u _c-u _a;

Expression formula according to each power component of formula (I)-Shi (VIII) derivation three-phase series VSC:

In formula (Ⅸ)-Shi (Ⅺ), P _a, P _b, P _cbe respectively the instantaneous active power mean value of A, B, C phase of three-phase series VSC;

(3) under generalized synchronization rotating coordinate system, each positive sequence, negative phase-sequence and zero-sequence component are:

In formula (XVIII), be DC quantity, for the d axle component of positive sequence voltage, for the q axle component of positive sequence voltage, for the d axle component of negative sequence voltage, for the q axle component of negative sequence voltage, for the d axle component of forward-order current, for the q axle component of forward-order current, for the d axle component of negative-sequence current, for the q axle component of negative-sequence current, for the d axle component of zero-sequence current, for the q axle component of zero-sequence current;

According to formula (XVIII), formula (Ⅻ) and formula (XIII), derive expression formula (XIX) and formula (XX):

P_{0} = \frac{3}{2} (u_{d}^{+} i_{d}^{+} + u_{q}^{+} i_{q}^{+} + u_{d}^{-} i_{d}^{-} + u_{q}^{-} i_{q}^{-}) - - - (X I X)

Q_{0} = \frac{3}{2} (u_{q}^{+} i_{d}^{+} - u_{d}^{+} i_{q}^{+} + u_{q}^{-} i_{d}^{-} - u_{d}^{-} i_{q}^{-}) - - - (X X)

According to formula (XIX) and (XX), each component of voltage when known, derive expression formula (XXI) and formula (XXII):

P_{0}^{*} = \frac{3}{2} (u_{d}^{+} i_{d}^{+ *} + u_{q}^{+} i_{q}^{+ *} + u_{d}^{-} i_{d}^{- *} + u_{q}^{-} i_{q}^{- *}) - - - (X X I)

Q_{0}^{*} = \frac{3}{2} (u_{q}^{+} i_{d}^{+ *} - u_{d}^{+} x_{q}^{+ *} + u_{q}^{-} R_{d}^{- *} - u_{d}^{-} i_{q}^{- *}) - - - (X X I I)

In formula (XXI) and formula (XXII), for the reference value of instantaneous active power mean value, for the reference value of instantaneous reactive power mean value, be respectively reference value;

(4) by P _a=P ₀/ 3, P _b=P ₀/ 3 and formula (XVIII) derive draw alternate power-balance condition, i.e. expression formula (XXIII) and formula (XXIV):

u_{d}^{-} i_{d}^{+} - u_{q}^{-} i_{q}^{+} + u_{d}^{+} i_{d}^{-} - u_{q}^{+} i_{q}^{-} + (u_{d}^{+} + u_{d}^{-}) i_{d}^{0} + (u_{q}^{+} - u_{q}^{-}) i_{q}^{0} = 0 - - - (X X I I I)

\begin{matrix} (- u_{d}^{-} - \sqrt{3} u_{q}^{-}) i_{d}^{+} + (u_{q}^{-} - \sqrt{2} u_{d}^{-}) i_{q}^{+} - (u_{d}^{+} + \sqrt{3} u_{q}^{+}) i_{d}^{-} + (u_{q}^{+} - \sqrt{3} u_{d}^{+}) i_{q}^{-} \\ + (- u_{d}^{+} + \sqrt{3} u_{q}^{+} - u_{d}^{-} + \sqrt{3} u_{q}^{-}) i_{d}^{0} + (- u_{q}^{+} - \sqrt{3} u_{d}^{+} + u_{q}^{-} + \sqrt{3} u_{d}^{-}) i_{q}^{0} = 0 \end{matrix} - - - (X X I V)

According to formula (XXIII) and (XXIV), each component of voltage when known, derive expression formula (XXV) and formula (XXVI):

u_{d}^{-} i_{d}^{+ *} - u_{q}^{-} i_{q}^{+ *} + u_{d}^{+} i_{d}^{- *} - u_{q}^{+} i_{q}^{- *} + (u_{d}^{+} + u_{d}^{-}) i_{d}^{0 *} + (u_{q}^{+} - u_{q}^{-}) i_{q}^{0 *} = 0 - - - (X X V)

\begin{matrix} (- u_{d}^{-} - \sqrt{3} u_{q}^{-}) i_{d}^{+ *} + (u_{q}^{-} - \sqrt{2} u_{d}^{-}) i_{q}^{+ *} - (u_{d}^{+} + \sqrt{3} u_{q}^{+}) i_{d}^{- *} + (u_{q}^{+} - \sqrt{3} u_{d}^{+}) i_{q}^{- *} \\ + (- u_{d}^{+} + \sqrt{3} u_{q}^{+} - u_{d}^{-} + \sqrt{3} u_{q}^{-}) i_{d}^{0 *} + (- u_{q}^{+} - \sqrt{3} u_{d}^{+} + u_{q}^{-} + \sqrt{3} u_{d}^{-}) i_{q}^{0 *} = 0 \end{matrix} - - - (X X V I)

In formula (XXV) and formula (XXVI), be respectively reference value;

(5) the secondary fluctuation of instantaneous active power is eliminated, i.e. P _c2=0, P _s2=0, derive expression formula (XXVII) and expression formula (XXVIII) by formula (XIV) and (XV):

u_{d}^{-} i_{d}^{+} + u_{q}^{-} i_{q}^{+} + u_{d}^{+} i_{d}^{-} + u_{q}^{+} i_{q}^{-} = 0 - - - (X X V I I)

u_{q}^{-} i_{d}^{+} - u_{d}^{-} i_{q}^{+} - u_{q}^{+} i_{d}^{-} + u_{d}^{+} i_{q}^{-} = 0 - - - (X X V I I I)

According to formula (XXVII) and (XXVIII), each component of voltage when known, derive expression formula (XXIX) and formula (XXX):

u_{d}^{-} i_{d}^{+ *} + u_{q}^{-} i_{q}^{+ *} + u_{d}^{+} i_{d}^{- *} + u_{q}^{+} i_{q}^{- *} = 0 - - - (X X I X)

u_{q}^{-} i_{d}^{+ *} - u_{d}^{-} i_{q}^{+ *} - u_{q}^{+} i_{d}^{- *} + u_{d}^{+} i_{q}^{- *} = 0 - - - (X X X)

(6) the secondary fluctuation of instantaneous reactive power is eliminated, i.e. Q _c2=0, Q _s2=0, derive expression formula (XXXI) and expression formula (XXXII) by formula (XVI) and (XVII):

- u_{d}^{-} i_{q}^{+} + u_{q}^{-} i_{d}^{+} - u_{d}^{+} i_{q}^{-} + u_{q}^{+} i_{d}^{-} = 0 - - - (X X X I)

- u_{q}^{-} i_{q}^{+} - u_{d}^{-} i_{d}^{+} + u_{q}^{+} i_{q}^{-} + u_{d}^{+} i_{d}^{-} = 0 - - - (X X X I I)

According to formula (XXXI) and (XXXII), each component of voltage when known, derive expression formula (XXXIII) and formula (XXXIV):

- u_{d}^{-} i_{q}^{+ *} + u_{q}^{-} i_{d}^{+ *} - u_{d}^{+} i_{q}^{- *} + u_{q}^{+} i_{d}^{- *} = 0 - - - (X X X I I I)

- u_{q}^{-} i_{q}^{+ *} - u_{d}^{-} i_{d}^{+ *} + u_{q}^{+} i_{q}^{- *} + u_{d}^{+} i_{d}^{- *} = 0 - - - (X X X I V)

(7) according to concrete control objectives, determine and ask for single-phase transformer secondary side current component:

A, as ensured grid alternating current stream three-phase symmetrical, single-phase transformer secondary side current component comprises formula (XXI), formula (XXII), formula (XXV) and formula (XXVI) form equation group, simultaneously solve single-phase transformer secondary side current component reference value

B, as need eliminate AC active power secondary fluctuation, single-phase transformer secondary side current component comprises formula (XXI), formula (XXII), formula (XXV), formula (XXVI), formula (XXIX) and (XXX) form equation group, solve single-phase transformer secondary side current component reference value

C, as need eliminate AC reactive power secondary fluctuation, single-phase transformer secondary side current component comprises (XXXIII and (XXXIV) form equation group, solve single-phase transformer secondary side current component for formula (XXI), formula (XXII), formula (XXV), formula (XXVI), formula reference value

(8) on the basis obtaining each current component reference value, by the current inner loop control realization based on pi controller under generalized synchronization coordinate system to the fast modulation of three-phase series VSC electric current.

2. a kind of universal control method being applicable to three-phase series VSC according to claim 1, is characterized in that, input u _a, u _b, u _c, detected by symmetrical component, output obtains input i _a, i _b, i _c, detected by symmetrical component, output obtains

3. a kind of universal control method being applicable to three-phase series VSC according to claim 1, is characterized in that, realizes described step (7) by constant dc power control.

4. according to the arbitrary described a kind of universal control method being applicable to three-phase series VSC of claim 1-3, it is characterized in that, described by the current inner loop control realization based on pi controller under generalized synchronization coordinate system to the fast modulation of three-phase series VSC electric current, concrete steps comprise:

A, to be obtained respectively by the inner ring current controller of correspondence: reference value reference value reference value by regulating it is right to realize quick control;

B, through Clarke conversion, under static a-b-c coordinate system addition obtains reference voltage