CN1303739C

CN1303739C - Automatic master-slave parallel control method for sine pulse width modulation inverter power supply

Info

Publication number: CN1303739C
Application number: CNB031080472A
Authority: CN
Inventors: 姜桂宾; 裴云庆; 王峰; 王兆安
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2003-05-20
Filing date: 2003-05-20
Publication date: 2007-03-07
Anticipated expiration: 2023-05-20
Also published as: CN1450706A

Abstract

The present invention discloses an automatic master-slave parallel control method of an SPWM inverter power supply. The present invention adopts the instantaneous reactive power principle and the output power characteristics of a parallel inverter power supply, namely that the active power of the output is controlled by changing the frequency of the output voltage of the inverter, and the reactive power of the output is controlled by the amplitude value of the output voltage of the inverter. Consequently, decoupling control can be carried out to the frequency or the phase position and the amplitude value of the inverter power supply by the output active power P and the reactive power Q. An interconnection signal wire exists in a system, but the signals transmitted by the interconnection signal wire are all direct current which can conveniently inhibit the interference in the process of long distance transmission. Consequently, the automatic master-slave parallel control method has the advantages of superior use value, good flow equalization effect and high stability of the voltage frequency and the amplitude value of the system in a distributed generation system and a UPS system. In the distributed generation system and the UPS system, the automatic master-slave parallel control method of an SPWM inverter power supply of the present invention has favorable application prospects.

Description

Automatic master-slave parallel control method for sinusoidal pulse width modulation inverter power supply

技术领域Technical field

本发明属于电气技术领域，涉及分布式发电系统、UPS等系统中的正弦脉宽调制逆变电源多机并联运行控制方法。The invention belongs to the field of electrical technology, and relates to a multi-machine parallel operation control method of a sinusoidal pulse width modulation inverter power supply in distributed power generation systems, UPS and other systems.

背景技术 Background technique

多台正弦脉宽调制逆变电源的并联运行可以扩大系统的容量，而且还可以组成并联冗余系统以提高系统的可靠性及可维护性。但是，正弦脉宽调制逆变电源的并联运行相对困难，因为所有并联运行的正弦脉宽调制逆变电源的频率、相位及幅值都必须一致，否则，各台逆变电源之间将存在很大的环流，过大的环流会使逆变器的负担加重，发散的环流将使系统崩溃，导致供电中断。The parallel operation of multiple sinusoidal pulse width modulation inverters can expand the capacity of the system, and can also form a parallel redundant system to improve the reliability and maintainability of the system. However, parallel operation of sinusoidal PWM inverters is relatively difficult, because the frequencies, phases and amplitudes of all sinusoidal PWM inverters operating in parallel must be the same, otherwise, there will be a lot of problems between the inverters. Large circulating current, excessive circulating current will increase the burden on the inverter, and divergent circulating current will cause the system to collapse and cause power supply interruption.

正弦脉宽调制逆变电源的并联运行控制方式一般分为集中控制、主从控制和无互联信号线独立控制方案。现有的集中控制方式需要检测总的负载电流，并通过较高带宽的信号线把负载电流的信息传递给所有的逆变电源模块，这严重影响了系统的扩容；系统中存在相互连接的信号线，使得系统的可靠性降低；系统不是冗余的，要在电流分配单元的控制下才能实现并联运行，一旦电流分配单元损坏，系统将崩溃。The parallel operation control methods of sinusoidal pulse width modulation inverter power supply are generally divided into centralized control, master-slave control and independent control schemes without interconnection signal lines. The existing centralized control method needs to detect the total load current, and transmit the information of the load current to all inverter power modules through the signal line with higher bandwidth, which seriously affects the expansion of the system; there are interconnected signals in the system line, which reduces the reliability of the system; the system is not redundant, and can only be operated in parallel under the control of the current distribution unit. Once the current distribution unit is damaged, the system will collapse.

与集中控制方式相比较，主从控制方式具有一定的优点，它可以不需检测负载电流的大小，使得系统易于扩展容量；并且逆变电源间的控制不受逆变电源输出线路阻抗的影响，系统的均流效果很好。但是主从控制方式也有一些不足：主模块的存在使得它不是一个冗余系统，一旦主模块出现故障，整个系统将会瘫痪；系统稳定性取决于并联的从模块个数；主模块与从模块之间存在电流指令信号线，不宜长距离铺设，否则信号会大大衰减、干扰严重、相位严重滞后。Compared with the centralized control method, the master-slave control method has certain advantages. It does not need to detect the size of the load current, making the system easy to expand capacity; and the control between the inverters is not affected by the output line impedance of the inverters. The current sharing effect of the system is very good. However, the master-slave control method also has some shortcomings: the existence of the master module makes it not a redundant system. Once the master module fails, the entire system will be paralyzed; the stability of the system depends on the number of parallel slave modules; There is a current command signal line between them, which should not be laid for a long distance, otherwise the signal will be greatly attenuated, the interference will be serious, and the phase will be seriously lagged.

与前两种并联控制方式比较，无互联信号线独立控制方式不需互联的控制信号线，通过输出电压的频率、幅值下垂控制来实现负载有功功率及无功功率的均分，从而实现负载电流的均分。这种方式尤其适用于分布式发电系统，但是，无功功率的均分受线路阻抗的影响较为严重，如果线路阻抗匹配不好，则负载所需无功功率将得不到很好均分，所以该方式对系统检测、控制精度要求很高；且这种方式由于采用下垂特性，会牺牲系统输出的电压频率、幅值稳定性指标。Compared with the previous two parallel control methods, the independent control method without interconnected signal lines does not require interconnected control signal lines. equalization of the current. This method is especially suitable for distributed power generation systems. However, the equal distribution of reactive power is seriously affected by the line impedance. If the line impedance is not well matched, the reactive power required by the load will not be well divided. Therefore, this method has high requirements for system detection and control accuracy; and this method will sacrifice the voltage frequency and amplitude stability indicators of the system output due to the droop characteristic.

发明内容Contents of Invention

由于集中控制、主从控制属于非冗余结构，当主从单元故障时将导致整个系统崩溃，系统可靠性差；并且存在大量控制信号线来传递交流时变的控制信号，信号在长距离传输的过程中衰减及干扰严重；同时，控制信号线的存在也不利于供电线路的铺设，系统的成本高。集中控制方式需要检测系统的负载电流，而在分布式发电系统中，负载也同样是分布的，负载电流的检测很难。因此，在分布式发电系统中，一般不易采用集中控制方式和主从控制方式。Since centralized control and master-slave control are non-redundant structures, when the master-slave unit fails, the entire system will collapse, and the system reliability will be poor; and there are a large number of control signal lines to transmit AC time-varying control signals, and the signal is transmitted over a long distance. Attenuation and interference are serious; at the same time, the existence of control signal lines is not conducive to the laying of power supply lines, and the cost of the system is high. The centralized control method needs to detect the load current of the system, and in the distributed generation system, the load is also distributed, and the detection of the load current is difficult. Therefore, in the distributed generation system, it is generally not easy to adopt the centralized control mode and the master-slave control mode.

本发明的目的在于，提供一种正弦脉宽调制逆变电源的自动主从并联控制方法，该方法是对正弦脉宽调制逆变电源的主从并联运行控制方式的改进。The object of the present invention is to provide an automatic master-slave parallel control method of sinusoidal pulse width modulation inverter power supply, which is an improvement on the master-slave parallel operation control mode of sinusoidal pulse width modulation inverter power supply.

实现上述发明目的的解决方案是：一种正弦脉宽调制逆变电源的自动主从并联控制方法，其特征在于，该方法至少包括以下步骤：The solution to realize the purpose of the above invention is: an automatic master-slave parallel control method for sinusoidal pulse width modulation inverter power supply, characterized in that the method at least includes the following steps:

将逆变电源自动主从控制系统中的有功主模块和无功主模块，通过自动选主单元的控制，自动把输出有功功率大的模块作为有功主模块，其余模块则为有功从模块，有功功率总线P_BUS的值由有功主模块的输出有功功率决定；通过自动选主单元的控制，自动把输出无功功率大的模块作为无功主模块，其余模块则为无功从模块，无功功率总线Q_BUS的值由无功主模块输出的无功功率决定，所有从模块输出的理想无功功率均应为Q_BUS的值；The active master module and reactive master module in the automatic master-slave control system of the inverter power supply are controlled by the automatic master unit selection, and the module with a large output active power is automatically regarded as the active master module, and the other modules are active slave modules. The value of the power bus P _BUS is determined by the output active power of the active main module; through the control of the automatic selection of the main unit, the module with a large output reactive power is automatically selected as the reactive main module, and the other modules are reactive slave modules. The value of the power bus Q _BUS is determined by the reactive power output by the reactive master module, and the ideal reactive power output by all slave modules should be the value of Q _BUS ;

每台逆变电源从模块通过采样自己输出的电流I和输出电压V₀计算输出的有功功率P_i和无功功率Q_i，并分别与有功功率总线P_BUS和无功功率总线Q_BUS比较，求出有功功率偏差和无功功率偏差，再以有功功率偏差作为相位_i补偿量、无功功率偏差作为幅值U_i补偿量来调整输出的电压，实现并联的各台逆变电源均分负载功率和逆变电源间的均流控制；Each inverter power supply slave module calculates the output active power P _i and reactive power Q _i by sampling its own output current I and output voltage V ₀ , and compares them with the active power bus P _BUS and reactive power bus Q _BUS respectively, Calculate the active power deviation and reactive power deviation, and then use the active power deviation as the phase  _i compensation amount, and the reactive power deviation as the amplitude U _i compensation amount to adjust the output voltage, so as to realize the equal distribution of the parallel inverters. Current sharing control between load power and inverter power supply;

系统中如果并联的逆变电源的容量不等，则按照逆变电源的容量将其输出的有功功率及无功功率按照下列标么化关系式进行处理：In the system, if the capacities of the inverters connected in parallel are different, the output active power and reactive power shall be processed according to the capacity of the inverters according to the following standardized relational formula:

$\frac{{P P}_{11}}{{S S}_{11}} = = \frac{{P P}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{P P}_{n no}}{{S S}_{n no}}$

$\frac{{Q Q}_{11}}{{S S}_{11}} = = \frac{{Q Q}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{Q Q}_{n no}}{{S S}_{n no}}$

式中：S₁、S₂…Sn表示逆变电源的额定容量；In the formula: S ₁ , S ₂ ...Sn represent the rated capacity of the inverter power supply;

即由每台逆变电源的功率计算单元应把实际输出的有功功率值及无功功率值送出之前，将它们按照标么化关系式进行处理。That is, before the power calculation unit of each inverter power supply sends out the actual output active power value and reactive power value, they should be processed according to the standardized relational formula.

本发明采用瞬时无功功率理论和并联逆变电源的输出功率特性，即通过改变逆变器的输出电压的频率来控制输出的有功功率；通过改变逆变器的输出电压幅值来控制输出的无功功率，从而把逆变电源的频率(相位)与幅值两个要素可以通过输出的有功功率P和无功功率Q进行近似解耦控制。系统虽存在互联信号线，但互联信号线所传递信号均为直流，可较为方便地抑制长距离传输的过程中的干扰，因此自动主从控制方式在分布式发电系统、UPS系统具有较高的实用价值，均流效果很好，系统的电压频率、幅值稳定性好。The present invention adopts the instantaneous reactive power theory and the output power characteristics of the parallel inverter power supply, that is, the output active power is controlled by changing the frequency of the output voltage of the inverter; the output voltage is controlled by changing the output voltage amplitude of the inverter. Reactive power, so that the frequency (phase) and amplitude of the inverter power supply can be approximately decoupled and controlled through the output active power P and reactive power Q. Although there are interconnected signal lines in the system, the signals transmitted by the interconnected signal lines are all direct current, which can easily suppress the interference during long-distance transmission. Therefore, the automatic master-slave control method has a high Practical value, the effect of current sharing is very good, and the voltage frequency and amplitude stability of the system are good.

附图说明Description of drawings

图1是两台逆变电源并联组网运行的等效电路图；Figure 1 is an equivalent circuit diagram of two inverters running in parallel in a network;

图2是自动主从控制技术原理图；Figure 2 is a schematic diagram of automatic master-slave control technology;

图3是自动选主控制电路示意图；Fig. 3 is a schematic diagram of an automatic master selection control circuit;

图4是逆变电源自动主从并联运行系统图；Figure 4 is a diagram of the automatic master-slave parallel operation system of the inverter power supply;

图5是数模混合型逆变电源自动主从并联控制框图；Fig. 5 is a block diagram of the automatic master-slave parallel control of the digital-analog hybrid inverter power supply;

图6是单台高性能逆变电源突加减桥式整流滤波负载时的输出电压波形及输出电流波形图；Figure 6 is the output voltage waveform and output current waveform diagram when a single high-performance inverter power supply suddenly adds or subtracts bridge rectifier filter load;

图7为两台逆变电源并联时的空载环流波形图；Figure 7 is a no-load circulating current waveform when two inverters are connected in parallel;

图8为突加减阻性负载时两台并联逆变电源的输出电流波形图；Figure 8 is the output current waveform diagram of two parallel inverter power supplies when the resistance-reducing load is suddenly added;

图9为突加减桥式整流滤波负载时两台并联逆变电源的输出电流波形图。Figure 9 is a waveform diagram of the output current of two parallel inverter power supplies when the bridge rectifier filter load is suddenly added or subtracted.

以下结合附图和发明人给出的实施例对本发明作进一步的详细描述。The present invention will be described in further detail below in conjunction with the accompanying drawings and the embodiments given by the inventor.

具体实施方式 Detailed ways

在介绍本发明的具体内容之前，首先介绍并联的逆变电源的输出功率特性，之后再详细分析自动主从并联组网控制策略及其实现方式。Before introducing the specific content of the present invention, first introduce the output power characteristics of the parallel inverter power supply, and then analyze in detail the automatic master-slave parallel networking control strategy and its implementation.

1.并联的逆变电源输出功率分析1. Analysis of output power of parallel inverter power supply

由逆变电源并联组成的分布式发电系统或UPS系统，是一个复杂的系统，各台逆变电源输出的交流电压可以等效为可控电压源，其频率、相位、幅值必须相互协调配合，共同负担负载电流，即要实现负载电流均衡控制。为了便于分析，以下以两台逆变电源并联组网运行为例进行分析。图1为两台逆变电源并联组网运行时的等效电路图，包括并联的两台理想逆变电源模块以及接在交流总线上的负载，其中Z₁、Z₂为线路阻抗，Z₀为负载阻抗。The distributed power generation system or UPS system composed of parallel inverters is a complex system. The AC voltage output by each inverter can be equivalent to a controllable voltage source, and its frequency, phase, and amplitude must be coordinated with each other. , to jointly bear the load current, that is, to achieve load current balance control. In order to facilitate the analysis, the following takes the parallel network operation of two inverter power supplies as an example for analysis. Figure 1 is the equivalent circuit diagram of two parallel inverter power supply modules, including two ideal inverter power supply modules connected in parallel and the load connected to the AC bus, where Z ₁ and Z ₂ are line impedances, and Z ₀ is load impedance.

在分布式发电系统中，线路的电阻较小，线路阻抗主要呈感性，即Z₁≈jωL₁、Z₂≈jωL₂，并假设图中两台并联供电的逆变电源的输出电压为标准正弦，且它们的容量分别为S₁、S₂，且S₂＝nS₁，则：In a distributed power generation system, the resistance of the line is small, and the line impedance is mainly inductive, that is, Z ₁ ≈ jωL ₁ , Z ₂ ≈ jωL ₂ , and it is assumed that the output voltage of the two inverters powered in parallel in the figure are standard sine, and their capacities are S ₁ , S ₂ respectively, and S ₂ =nS ₁ , then:

逆变器1供给负载的复功率为：The complex power supplied by inverter 1 to the load is:

${S S}_{11} = = {P P}_{11} + + j j {Q Q}_{11} = = {U u}_{00} {\overset{\cdot &Center Dot;}{I I}}_{11} - - - - - - ((11))$

逆变器1的输出电流为：The output current of inverter 1 is:

由式(1)、(2)得出：From the formulas (1) and (2), we get:

由于一般逆变器的输出电压

与系统电压

之间的相位差很小，则sin₁≈₁，如果令U₁＝k₁U₀则由式(3)得出：Since the output voltage of the general inverter

vs. system voltage

The phase difference between them is very small, then sin ₁ ≈ ₁ , if U ₁ =k ₁ U ₀ is set, it can be obtained from formula (3):

式中 $k_{P 1} = \frac{K_{1} U_{0}^{2}}{ω L_{1}}$ 为有功功率系数；

为无功功率系数；In the formula

k_{P}

1 = \frac{K_{1} u_{0}^{2}}{ω L_{1}}

is the active power coefficient;

is the reactive power coefficient;

${Q Q}_{0101} = = \frac{{U u}_{00}^{22}}{ω ω {L L}_{11}}$

同理得出逆变电源2的输出功率为：Similarly, the output power of the inverter power supply 2 is obtained as:

根据式(4)、(5)可以得出并联的各逆变电源输出的功率特性：According to equations (4) and (5), the output power characteristics of each parallel inverter power supply can be obtained:

1)逆变电源输出的有功功率主要取决于相位角，并与相位差呈正比，相位差超前者发出有功功率，反之吸收有功功率；相位差越大发出或吸收的有功功率越大。逆变电源相位角的调节是通过微调频率f来实现的，因此，要调节各逆变电源输出的有功功率，只需对输出电压的频率作相应的调整。1) The active power output by the inverter power supply mainly depends on the phase angle , and is proportional to the phase difference. The phase difference exceeds the former to emit active power, and vice versa to absorb active power; the greater the phase difference, the greater the active power emitted or absorbed. The adjustment of the phase angle  of the inverter power supply is realized by fine-tuning the frequency f. Therefore, to adjust the active power output by each inverter power supply, it is only necessary to adjust the frequency of the output voltage accordingly.

2)逆变电源输出的无功功率则主要取决于输出的电压幅值U，幅值高者发出无功功率，反之吸收无功功率；输出电压的幅值差值越大，发出或吸收的无功功率越大。2) The reactive power output by the inverter power supply mainly depends on the output voltage amplitude U, the one with the higher amplitude emits reactive power, and vice versa absorbs reactive power; the greater the amplitude difference of the output voltage, the greater the output voltage amplitude U The greater the reactive power.

通过改变逆变器的输出电压的频率来控制输出的有功功率、通过改变逆变器的输出电压幅值来控制输出的无功功率，从而把逆变电源的频率(相位)与幅值两个要素通过输出的有功功率P和无功功率Q进行非严格的近似解耦控制。本发明有关逆变电源自动主从并联组网同步运行控制策略和无互联信号线独立控制策略正是基于这种功率特性来实现的。The output active power is controlled by changing the frequency of the inverter output voltage, and the output reactive power is controlled by changing the output voltage amplitude of the inverter, so that the frequency (phase) and amplitude of the inverter power supply are two The elements carry out non-strict approximate decoupling control through the output active power P and reactive power Q. The automatic master-slave parallel networking synchronous operation control strategy of the inverter power supply and the independent control strategy without interconnection signal lines in the present invention are realized based on this power characteristic.

2.自动主从并联组网控制策略2. Automatic master-slave parallel networking control strategy

2.1自动主从并联控制原理2.1 Principle of automatic master-slave parallel control

自动主从控制技术是一种冗余的并联系统，它是基于并联的逆变电源输出的功率特性来控制的，即：并联的逆变电源输出的有功功率主要取决于相位角，相位差超前者发出有功功率，反之吸收有功功率；并联逆变电源输出的无功功率则主要取决于输出的电压幅值U，幅值高者发出无功功率，反之吸收无功功率。逆变电源相位角的调节是通过微调频率f来实现的，要调节各逆变电源输出的有功功率，只需对输出电压的频率作相应的调整。因此，可以通过改变逆变器的输出电压的频率来控制输出的有功功率；通过改变逆变器的输出电压幅值来控制输出的无功功率，从而把逆变电源的频率(相位)与幅值两个要素可以通过输出的有功功率P和无功功率Q进行近似解耦控制。逆变电源在并联运行时，各电源模块可根据自身的容量和输出的有功调节量ΔP、无功调节量ΔQ，然后对其频率给定f_r、电压幅值给定U_r进行相应的调节来实现负载电流的均分和环流的抑制。Automatic master-slave control technology is a redundant parallel system, which is controlled based on the power characteristics of the parallel inverter power output, that is: the active power output by the parallel inverter power supply mainly depends on the phase angle , the phase difference The former emits active power, and vice versa absorbs active power; the reactive power output by parallel inverters mainly depends on the output voltage amplitude U, and the one with a higher amplitude emits reactive power, and vice versa absorbs reactive power. The adjustment of the phase angle  of the inverter power supply is realized by fine-tuning the frequency f. To adjust the active power output by each inverter power supply, it is only necessary to adjust the frequency of the output voltage accordingly. Therefore, the output active power can be controlled by changing the frequency of the inverter output voltage; the output reactive power can be controlled by changing the output voltage amplitude of the inverter, so that the frequency (phase) and amplitude of the inverter power supply The two elements of value can be approximately decoupled and controlled by the output active power P and reactive power Q. When the inverter power supply is running in parallel, each power module can adjust its frequency f _r and voltage amplitude U _r according to its own capacity and output active power adjustment ΔP and reactive power adjustment ΔQ To achieve load current sharing and suppression of circulating current.

图2为自动主从控制技术的原理图。从图中可以看出，并联的每台逆变电源拥有自己的振荡器、电压波形控制器，以及自动有功功率选主控制单元、自动无功功率选主控制单元。系统通过自动选主单元的控制，自动把输出有功功率大的模块作为有功主模块，其余模块则为有功从模块，有功功率总线P_BUS的值由有功主模块的输出有功功率功率决定；系统通过自动选主单元的控制，自动把输出无功功率大的模块作为无功主模块，其余模块则为无功从模块，无功功率总线Q_BUS的值由无功主模块输出的无功功率决定，所有从模块输出的理想无功功率均应为Q_BUS的值。因此系统中同时存在有功主模块和无功主模块。Figure 2 is a schematic diagram of automatic master-slave control technology. It can be seen from the figure that each parallel inverter power supply has its own oscillator, voltage waveform controller, automatic active power selection main control unit, and automatic reactive power selection main control unit. Through the control of the automatic selection of the master unit, the system automatically selects the module with a large output active power as the active master module, and the other modules are active slave modules. The value of the active power bus P _BUS is determined by the output active power of the active master module; the system passes Automatically select the control of the main unit, automatically select the module with large output reactive power as the reactive main module, and the other modules are the reactive slave modules, and the value of the reactive power bus Q _BUS is determined by the reactive power output by the reactive main module , all ideal reactive power output from the module should be the value of Q _BUS . Therefore, there are active main modules and reactive main modules in the system at the same time.

假如某一台逆变电源输出有功功率P_i和无功功率Q_i不是理想的P_BUS之和Q_BUS之值，则其偏差为：If a certain inverter output active power P _i and reactive power Q _i is not the ideal value of P _BUS and Q _BUS , then its deviation is:

$\{\begin{matrix} Δ Δ {P P}_{i i} = = {P P}_{BUS BUS} - - {P P}_{i i} \\ Δ Δ {Q Q}_{i i} = = {Q Q}_{BUS BUS} - - {Q Q}_{i i} \end{matrix} - - - - - - ((66))$

由公式(4)可以得出逆变电源i输出的有功功率偏差及无功功率偏差为：From formula (4), it can be concluded that the active power deviation and reactive power deviation output by inverter i are:

因此要使得每台逆变电源从模块实现输出功率与主模块的一致，只要每台逆变电源从模块通过采样自己输出的电流I和输出电压V₀来计算输出的有功功率P_i和无功功率Q_i，并分别与有功功率总线P_BUS和无功功率总线Q_BUS比较，求出偏差ΔP_i和ΔQ_i，再以ΔP_i作为相位_i补偿量、ΔQ_i作为幅值U_i补偿量来调整输出的电压，实现并联的各台逆变电源均分负载功率，从而实现了逆变电源间高精度的均流控制。Therefore, to make the output power of each inverter power slave module consistent with that of the main module, as long as each inverter power slave module calculates the output active power P _i and reactive power by sampling its own output current I and output voltage V ₀ The power Q _i is compared with the active power bus P _BUS and the reactive power bus Q _BUS respectively, and the deviations ΔP _i and ΔQ _i are obtained, and then ΔP _i is used as the phase  _i compensation amount, and ΔQ _i is used as the amplitude U _i compensation amount To adjust the output voltage, realize the equal load power sharing of each inverter power supply in parallel, so as to realize the high-precision current sharing control among the inverter power supplies.

在系统中如果并联的逆变电源的容量不等，则要按照逆变电源的容量将其输出的有功功率及无功功率进行标么化处理，从而使得各逆变电源能够按其容量来负担负载的有功功率及无功功率，即容量大的逆变电源输出较多的功率，容量小的逆变电源输出较少的功率。标么化关系式为：In the system, if the capacities of the inverters connected in parallel are not equal, the output active power and reactive power shall be standardized according to the capacity of the inverters, so that each inverter can bear the burden according to its capacity. The active power and reactive power of the load, that is, the inverter power supply with large capacity outputs more power, and the inverter power supply with small capacity outputs less power. The normalization relation is:

$\frac{{P P}_{11}}{{S S}_{11}} = = \frac{{P P}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{P P}_{n no}}{{S S}_{n no}} - - - - - - ((88))$

$\frac{{Q Q}_{11}}{{S S}_{11}} = = \frac{{Q Q}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{Q Q}_{n no}}{{S S}_{n no}} - - - - - - ((99))$

即由每台逆变电源的功率计算单元应把实际输出的有功功率值及无功功率值送出之前，应将它们除以逆变电源的额定容量S_i进行标么化处理。That is, before the power calculation unit of each inverter power supply sends out the actual output active power value and reactive power value, they should be divided by the rated capacity S _i of the inverter power supply for standardization.

2.2自动选主控制单元的原理及其实现方案2.2 The principle and implementation plan of automatic selection of master control unit

自动选主控制单元是自动主从并联控制方案的一个关键环节，它根据并联的各台逆变电源模块的输出的有功功率和无功功率来确定系统的有功主模块和无功主模块。输出有功功率大的模块被指定为有功主模块，有功主模块自动竞争得到有功功率总线P_BUS，并把自己输出有功功率之值输出到有功功率总线P_BUS上，而其它所有的有功从模块则自动放弃对有功功率总线P_BUS的竞争，并把有功功率总线P_BUS的值作为自己输出有功功率的基准，即所有的有功从模块按照P_BUS之值来调节自己输出的有功功率；同理，输出无功功率大的模块被指定为无功主模块，无功主模块自动竞争得到无功功率总线Q_BUS，并把自己输出无功功率之值输出到无功功率总线Q_BUS上，而其它所有的无功从模块则自动放弃对无功功率总线Q_BUS的竞争，并把无功功率总线Q_BUS的值作为自己输出无功功率的基准，即所有的无功从模块按照Q_BUS之值来调节自己输出的无功功率。The automatic selection of master control unit is a key part of the automatic master-slave parallel control scheme. It determines the active master module and reactive master module of the system according to the output active power and reactive power of each parallel inverter power supply module. The module with a large output active power is designated as the active master module, and the active master module automatically competes to obtain the active power bus P _BUS , and outputs the value of its own output active power to the active power bus P _BUS , while all other active slave modules are Automatically give up the competition for the active power bus P _BUS , and take the value of the active power bus P _BUS as the benchmark for its output active power, that is, all active slave modules adjust their output active power according to the value of P _BUS ; similarly, The module with large output reactive power is designated as the reactive main module, and the reactive main module automatically competes to obtain the reactive power bus Q _BUS , and outputs the value of its output reactive power to the reactive power bus Q _BUS , while other All reactive slave modules automatically give up the competition for the reactive power bus Q _BUS , and take the value of the reactive power bus Q _BUS as the benchmark for their output reactive power, that is, all reactive slave modules follow the value of Q _BUS To adjust the reactive power output by itself.

自动选主控制电路，如图3所示。在图中，由于二极管的单向导电性，只有有功(无功)功率最大的模块，二极管才导通，有功(无功)功率母线的值等于输出有功(无功)功率最大的模块的有功(无功)功率值。在正常情况下，各模块输出的有功(无功)是相等的，如果i^#模块输出的有功(无功)功率突然增大，成为n个模块中最大的一个，于是，P_i(Q_i)上升，该模块自动成为有功(无功)主模块，其它模块为从模块，这时，P_BUS＝P_i(Q_BUS＝Q_i)，主模块的ΔP_i＝0(ΔQ_i＝0)，而各从模块的P_k(Q_k)与P_BUS(Q_BUS)比较，产生有功(无功)功率误差ΔP_k(ΔQ_k)，由此误差来调整其输出电压的频率(幅值)，从而实现自动均分负载功率。Automatic selection of the main control circuit, as shown in Figure 3. In the figure, due to the unidirectional conductivity of the diode, only the module with the largest active (reactive) power can conduct the diode, and the value of the active (reactive) power bus is equal to the active power of the module with the largest output active (reactive) power (reactive) power value. Under normal circumstances, the active (reactive) power output by each module is equal. If the active (reactive) power output by the i ^# module suddenly increases and becomes the largest one among the n modules, then, P _i (Q _i ) rises, the module automatically becomes active (reactive) master module, and other modules are slave modules. At this time, P _BUS =P _i (Q _BUS =Q _i ), and ΔP _i of the master module =0 (ΔQ _i =0) , and the P _k (Q _k ) of each slave module is compared with P _BUS (Q _BUS ), resulting in an active (reactive) power error ΔP _k (ΔQ _k ), which is used to adjust the frequency (amplitude) of its output voltage , so as to realize automatic load power sharing.

由于图3中的二极管包含在电压跟随器的内部，不存在二极管的正向压降带来的功率均分误差，因此，在理论上不存在功率均分误差。实用电路中，自动选主及功率均分控制均采用比例控制，这使得系统稳定性好，功率均分控制的动态响应速度快。这个自动选主控制电路的另一个优点是有功功率总线P_BUS和无功功率总线Q_BUS是低阻抗的，对噪声不敏感。Since the diode in Figure 3 is included inside the voltage follower, there is no power sharing error caused by the forward voltage drop of the diode, so theoretically there is no power sharing error. In the practical circuit, proportional control is adopted for automatic master selection and power sharing control, which makes the system stable and the dynamic response speed of power sharing control is fast. Another advantage of this automatic master selection control circuit is that the active power bus P _BUS and the reactive power bus Q _BUS are low impedance and insensitive to noise.

根据以上分析，制定出了正弦脉宽调制逆变电源自动主从控制方法，系统如图4所示。结合图4，进一步说明逆变电源自动主从控制的工作过程。假设i^#逆变电源模块的输出有功功率P_i大于其余各模块，则有功功率总线P_BUS被运放A_Pi驱动，则P_BUS＝P_i，i^#逆变电源模块为有功主模块，其余模块为有功从模块，得出According to the above analysis, the automatic master-slave control method of the sinusoidal pulse width modulation inverter power supply is worked out, and the system is shown in Figure 4. Combined with Figure 4, the working process of the automatic master-slave control of the inverter power supply is further described. Assuming that the output active power P _i of i ^#inverter power supply module is greater than other modules, the active power bus P _BUS is driven by the operational amplifier A _Pi , then P _BUS =P _i , i ^#inverter power supply module is the active main module, and the rest The module is an active slave module, and the

ΔP_j＝P_i-P_j＞0，(其中j≠i)ΔP _j =P _i -P _j >0, (where j≠i)

因此 Δf_j＞0，Therefore Δf _j > 0,

从而 f_j＝f_rj+Δf_j Thus f _j = f _rj +Δf _j

即j^#逆变电源模块输出电压的频率是在其给定频率f_rj的基础上补偿Δf_j，使其输出电压的频率提高，输出电压的相位向前移动，从而使得j^#逆变电源模块的输出有功功率P_j逐渐增加；在P_j增加的过程中，i^#逆变电源模块的频率保持不变，而其相位却相对向后移动，即P_i逐渐减小。最终，并联运行的各逆变电源模块输出的有功功率趋于相等。在有功的均衡调节过程中，同时也实现了各台逆变电源的频率、相位的同步控制。同理，可以实现无功功率的均分。That is, the frequency of the output voltage of the j ^#inverter power module is to compensate Δf _j on the basis of its given frequency f _rj , so that the frequency of the output voltage increases, and the phase of the output voltage moves forward, so that j ^#inverter power module The output active power P _j of the output gradually increases; in the process of P _j increasing, the frequency of i ^# inverter power module remains unchanged, but its phase moves backward relatively, that is, P _i gradually decreases. Eventually, the active power output by each inverter power supply module running in parallel tends to be equal. In the process of active power balance adjustment, the synchronous control of the frequency and phase of each inverter power supply is also realized. Similarly, the equal sharing of reactive power can be realized.

逆变电源的自动主从并联运行控制过程中，存在有功主模块和无功主模块，系统的频率由有功主模块的给定基准频率决定，系统的电压幅值由无功主模块的输出电压(给定基准电压)决定，因此系统的频率及电压幅值是稳定的，系统的频率精度及幅值精度可以做的很高。同时，各逆变电源输出的有功功率的一致性及无功功率的一致性都很好。In the automatic master-slave parallel operation control process of the inverter power supply, there are active master modules and reactive master modules, the frequency of the system is determined by the given reference frequency of the active master module, and the voltage amplitude of the system is determined by the output voltage of the reactive master module (given reference voltage), so the frequency and voltage amplitude of the system are stable, and the frequency accuracy and amplitude accuracy of the system can be made very high. At the same time, the consistency of the active power output by each inverter power supply and the consistency of the reactive power are very good.

2.3自动主从并联组网控制方案的实现电路2.3 Implementation circuit of automatic master-slave parallel networking control scheme

根据以上分析，本发明提出了一种高性能的数模混合型逆变电源自动主从并联控制方案，其控制框图如图5所示。它采用高速数字信号处理器TMS320F240及外扩12位A/D检测输出的电压、电流、有功功率总线P_BUS以及无功功率总线Q_BUS，并基于瞬时无功功率理论，计算出逆变电源的输出有功功率P、无功功率Q，然后计算出频率f及幅值U，再合成给定电压指令，最后经12位D/A转换后送至高性能逆变电源，逆变电源就会按照给定的电压指令输出正弦电压。According to the above analysis, the present invention proposes a high-performance digital-analog hybrid inverter power automatic master-slave parallel control scheme, the control block diagram of which is shown in Figure 5. It uses a high-speed digital signal processor TMS320F240 and an externally expanded 12-bit A/D to detect the output voltage, current, active power bus P _BUS and reactive power bus Q _BUS , and based on the theory of instantaneous reactive power, calculates the inverter power supply Output active power P and reactive power Q, then calculate the frequency f and amplitude U, then synthesize a given voltage command, and finally send it to a high-performance inverter power supply after 12-bit D/A conversion, and the inverter power supply will follow the given voltage command. A given voltage command outputs a sinusoidal voltage.

要实现有功电流及无功电流的均分，减小逆变器之间的环流，必须提高逆变电源频率及幅值的控制分辨率，尤其是频率的分辨率。本发明所采用的控制方案中，DSP发出的电压指令的频率调节分辨率为二十万分之一，这足以保证逆变器的有功功率的均分；DSP发出的电压指令的幅值调节分辨率为四千分之一，足以保证逆变器的无功功率均分，使并联的系统稳定的运行。In order to realize the equal sharing of active current and reactive current and reduce the circulating current between inverters, it is necessary to improve the control resolution of frequency and amplitude of inverter power supply, especially the resolution of frequency. In the control scheme adopted by the present invention, the frequency adjustment resolution of the voltage command issued by DSP is 1/200,000, which is enough to ensure the equal sharing of the active power of the inverter; the amplitude adjustment resolution of the voltage command issued by DSP The rate is 1/4000, which is enough to ensure the equal sharing of the reactive power of the inverter and make the parallel system operate stably.

高性能逆变电源作为电压给定指令的执行机构，它具有高稳定性、高稳压精度、输出高正弦度。它采用一种新颖的控制方案，此方案结构简单，仅有两个简单PI调节环：瞬时电压波形外环、高速电容电流内环。瞬时电压外环保证输出电压的跟踪精度，高速、低稳态误差的电容电流内环可以克服因负载波动或扰动电压对输出波形的影响，使得逆变电源实现了输出电压接近纯正弦，并且非线性负载适应能力强，在二极管整流负载条件下输出电压谐波总畸变率小，动态响应速度快，突加减负载时调节过程短，输出电压精度高。The high-performance inverter power supply is used as the actuator of the voltage given command, and it has high stability, high precision of voltage regulation, and high output sine degree. It adopts a novel control scheme with simple structure and only two simple PI regulation loops: the outer loop of instantaneous voltage waveform and the inner loop of high-speed capacitive current. The instantaneous voltage outer loop ensures the tracking accuracy of the output voltage, and the high-speed, low steady-state error capacitive current inner loop can overcome the influence of the load fluctuation or disturbance voltage on the output waveform, so that the inverter power supply can achieve an output voltage close to pure sine, and non-destructive Strong linear load adaptability, low total harmonic distortion rate of output voltage under diode rectification load conditions, fast dynamic response speed, short adjustment process when load is suddenly added or decreased, and high output voltage accuracy.

由于高性能逆变电源采用电压波形控制技术，在逆变器并联系统中，线路阻抗不可缺少，否则，逆变器的电压波形环会失效，使逆变器不能正常工作。在实际的逆变电源并联系统中，每台逆变电源的输出串入了一个适当的阻抗。串入线路阻抗会使得非线性负载的电压波形有一定畸变，但它可以抑制并联逆变电源间的谐波环流，使得逆变电源均分负载的失真功率，而不必从控制上考虑失真功率的均分。Since the high-performance inverter power supply adopts the voltage waveform control technology, in the inverter parallel system, the line impedance is indispensable, otherwise, the voltage waveform loop of the inverter will fail, so that the inverter cannot work normally. In the actual parallel system of inverter power supply, the output of each inverter power supply is connected in series with an appropriate impedance. Connecting the line impedance in series will distort the voltage waveform of the nonlinear load, but it can suppress the harmonic circulation between the parallel inverters, so that the inverters can share the distortion power of the load evenly, without having to consider the distortion power from the control point of view. split evenly.

2.4自动主从并联控制的实验结果2.4 Experimental results of automatic master-slave parallel control

根据本发明提出的数模混合型逆变电源自动主从并联控制方法，制作了两台逆变电源的并联系统，每台逆变电源的主要参数如下：容量为1.5kVA，开关频率为20kHz，空载输出电压为110V，空载输出电压频率为50Hz，串联线路阻抗为0.2mH。图6～9为相关的实验波形。According to the digital-analog hybrid inverter power automatic master-slave parallel control method proposed by the present invention, a parallel system of two inverter power supplies has been made, and the main parameters of each inverter power supply are as follows: the capacity is 1.5kVA, the switching frequency is 20kHz, The no-load output voltage is 110V, the no-load output voltage frequency is 50Hz, and the series line impedance is 0.2mH. Figures 6 to 9 are related experimental waveforms.

图6为单台高性能逆变电源在突加减桥式整流滤波负载时的输出电压波形及输出电流波形。从图6可以看出：高性能逆变电源在突加减桥式整流滤波负载时，输出电压波形基本保持不变(实际测量空载及加载时的输出电压有效值均约为110V)，并且在突加减负载时，输出电压的动态调整过程十分短暂(实际测量调节时间为200μs)，加载后输出电压的谐波总畸变率(THD)为0.17％。Figure 6 shows the output voltage waveform and output current waveform of a single high-performance inverter power supply when the bridge rectifier filter load is suddenly added or subtracted. It can be seen from Figure 6 that when the high-performance inverter power supply suddenly adds or subtracts bridge rectifier and filter loads, the output voltage waveform remains basically unchanged (the effective value of the output voltage measured at no-load and loaded is about 110V), and When the load is suddenly added or subtracted, the dynamic adjustment process of the output voltage is very short (the actual measurement adjustment time is 200μs), and the total harmonic distortion (THD) of the output voltage after loading is 0.17%.

图7为两台逆变电源并联时的空载环流波形，实际测量空载环流的有效值约为0.05A，仅为额定输出电流的0.4％。Figure 7 shows the no-load circulating current waveform when two inverters are connected in parallel. The actual measured no-load circulating current effective value is about 0.05A, which is only 0.4% of the rated output current.

图8为突加减阻性负载时两台并联逆变电源的输出电流波形，两台逆变电源输出的电流峰值分别为5.4A、5.5A。Figure 8 shows the output current waveforms of two parallel inverters when the resistance-reducing load is suddenly added. The peak currents output by the two inverters are 5.4A and 5.5A respectively.

图9为突加减桥式整流滤波负载时两台并联逆变电源的输出电流波形，两台逆变电源输出的电流峰-峰值分别为33.8A和32.2A。从图9、10可以看出，负载电流均分的效果很好。Figure 9 shows the output current waveforms of two parallel inverters when the bridge rectifier and filter load is suddenly added or subtracted. The peak-to-peak currents output by the two inverters are 33.8A and 32.2A, respectively. It can be seen from Figures 9 and 10 that the effect of load current sharing is very good.

3.发明效果3. Invention effect

逆变电源的自动主从并联运行控制过程中，系统的频率由有功主模块的给定基准频率决定，系统的电压幅值由无功主模块的输出电压(给定基准电压)决定，因此系统的频率及电压幅值是稳定的，系统的频率精度及幅值精度可以做的很高；同时，由于功率均分环为外环，可以克服包含在环内的逆变电源的所有误差(包括各逆变电源因检测、控制而带来的输出电压的频率、相位和幅值的误差，以及直流母线的波动、负载的波动等等)，从而各逆变电源输出的有功功率的一致性及无功功率的一致性都很好，逆变电源间的均流效果很好。During the automatic master-slave parallel operation control process of the inverter power supply, the frequency of the system is determined by the given reference frequency of the active main module, and the voltage amplitude of the system is determined by the output voltage (given reference voltage) of the reactive main module. Therefore, the system The frequency and voltage amplitude are stable, and the frequency accuracy and amplitude accuracy of the system can be made very high; at the same time, because the power equalizing loop is an outer loop, it can overcome all errors of the inverter power supply included in the loop (including The frequency, phase and amplitude errors of the output voltage brought about by the detection and control of each inverter power supply, as well as the fluctuation of the DC bus, the fluctuation of the load, etc.), so that the consistency of the active power output by each inverter power supply and The consistency of reactive power is very good, and the current sharing effect between inverter power sources is very good.

自动主从控制并联系统的并联控制不检测负载的电流，因此负载可以是分布的。并联运行的各台逆变电源可以按照其容量来分担负载的有功功率、无功功率，并且不受线路阻抗的影响。Automatic master-slave control The parallel control of the parallel system does not detect the current of the load, so the load can be distributed. Each inverter power supply running in parallel can share the active power and reactive power of the load according to its capacity, and is not affected by the line impedance.

系统的并联组网控制是在自动选主控制单元的控制下完成的。自动选主控制在理论上不存在功率均分误差，并且自动选主及功率均分控制均采用比例控制，这使得系统稳定性好，功率均分控制的动态响应速度快。这个自动选主控制电路的另一个优点是有功功率总线P_BUS和无功功率总线Q_BUS是低阻抗的，对噪声不敏感，无论功率总线是开路的还是短路的，不影响每个模块的性能。The parallel network control of the system is completed under the control of the automatic master control unit. In theory, there is no power sharing error in automatic master selection control, and both automatic master selection and power sharing control adopt proportional control, which makes the system stable and the dynamic response speed of power sharing control is fast. Another advantage of this automatic master selection control circuit is that the active power bus P _BUS and reactive power bus Q _BUS are low impedance and insensitive to noise, no matter the power bus is open or short circuit, it will not affect the performance of each module .

虽然系统中存在有功功率总线P_BUS和无功功率总线Q_BUS，在一定程度上降低了系统的可靠性，增加了系统的成本，但与集中控制、传统的主从控制相比，这两条总线传递的信号基本为直流信号，信号线的通频带宽不需要太高，如果适当的增加一些滤波环节，消除干扰，则这两条总线可以较长距离铺设。而在集中控制、主从控制中，逆变电源模块之间的电流指令信号线，在线性负载的情况下传输的是一个基波频率的交流信号，在非线性负载的情况下，此指令信号线传输的是一个包含高频谐波的基波信号，因此电流指令信号线不易长距离铺设，否则信号衰减、干扰严重。Although there are active power bus P _BUS and reactive power bus Q _BUS in the system, which reduces the reliability of the system to a certain extent and increases the cost of the system, compared with centralized control and traditional master-slave control, these two The signal transmitted by the bus is basically a DC signal, and the bandwidth of the signal line does not need to be too high. If some filtering links are appropriately added to eliminate interference, the two buses can be laid over a longer distance. In centralized control and master-slave control, the current command signal line between the inverter power supply modules transmits an AC signal with a fundamental frequency in the case of a linear load. In the case of a nonlinear load, the command signal The line transmits a fundamental wave signal containing high-frequency harmonics, so the current command signal line is not easy to lay for a long distance, otherwise the signal attenuation and interference will be serious.

自动主从控制是一个冗余的系统，每台逆变电源模块在物理结构上的地位是等同的，任何一台逆变电源(包括主模块)故障时，只要其能够快速退出系统就不影响整个系统的正常运行，系统的可靠性很高。Automatic master-slave control is a redundant system, each inverter power supply module has the same status in the physical structure, when any inverter power supply (including the main module) fails, as long as it can quickly exit the system, it will not affect The normal operation of the whole system, the reliability of the system is very high.

综上所述，在分布式发电、UPS等系统中，本发明的正弦脉宽调制逆变电源的自动主从并联控制方法，具有良好的应用前景。In summary, in systems such as distributed power generation and UPS, the automatic master-slave parallel control method of the sinusoidal pulse width modulation inverter power supply of the present invention has a good application prospect.

Claims

1. The automatic master-slave parallel control method of sinusoidal pulse width modulation inverter power supply, it is characterized in that, the method comprises the following steps at least:

The active master module and reactive master module in the automatic master-slave control system of the inverter power supply are controlled by the automatic master unit selection, and the module with a large output active power is automatically regarded as the active master module, and the other modules are active slave modules. The value of the power bus P _BUS is determined by the output active power of the active main module; through the control of the automatic selection of the main unit, the module with a large output reactive power is automatically selected as the reactive main module, and the other modules are reactive slave modules. The value of the power bus Q _BUS is determined by the reactive power output by the reactive master module, and the ideal reactive power output by all slave modules should be the value of Q _BUS ;

Each inverter power supply slave module calculates the output active power P _i and reactive power Q _i by sampling its own output current I and output voltage V ₀ , and compares them with the active power bus P _BUS and reactive power bus Q _BUS respectively, Calculate the active power deviation and reactive power deviation, and then use the active power deviation as the phase  _i compensation amount, and the reactive power deviation as the amplitude U _i compensation amount to adjust the output voltage, so as to realize the equal distribution of the parallel inverters. Current sharing control between load power and inverter power supply;

In the system, if the capacities of the inverters connected in parallel are different, the output active power and reactive power shall be processed according to the capacity of the inverters according to the following standardized relational formula:

\frac{{P P}_{11}}{{S S}_{11}} = = \frac{{P P}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{P P}_{n no}}{{S S}_{n no}}

\frac{{Q Q}_{11}}{{S S}_{11}} = = \frac{{Q Q}_{22}}{{S S}_{22}} = = \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; \cdot &Center Dot; = = \frac{{Q Q}_{n no}}{{S S}_{n no}}

In the formula: S ₁ , S ₂ ...Sn represent the rated capacity of the inverter power supply, that is, before the power calculation unit of each inverter power supply sends out the actual output active power value and reactive power value, they should be calculated according to the standard Relational expressions are processed.