WO2014079124A1 - Model prediction control method for voltage source-type rectifier when grid voltage is unbalanced - Google Patents

Model prediction control method for voltage source-type rectifier when grid voltage is unbalanced Download PDF

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Publication number
WO2014079124A1
WO2014079124A1 PCT/CN2012/087218 CN2012087218W WO2014079124A1 WO 2014079124 A1 WO2014079124 A1 WO 2014079124A1 CN 2012087218 W CN2012087218 W CN 2012087218W WO 2014079124 A1 WO2014079124 A1 WO 2014079124A1
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voltage
grid
phase
current
coordinate system
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PCT/CN2012/087218
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French (fr)
Chinese (zh)
Inventor
夏长亮
何湘宁
李瑞来
周发强
王志强
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天津大学
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Publication of WO2014079124A1 publication Critical patent/WO2014079124A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H02M7/53876—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Definitions

  • the invention relates to a control method of a voltage source type rectifier under an unbalanced grid voltage, and belongs to the field of power converter control.
  • the voltage source type pulse width modulation rectifier has the advantages of grid side voltage sinusoidal, unit power factor, energy bidirectional flow and constant DC voltage control, which can realize "green conversion” of electric energy, so in industrial DC power supply, variable frequency speed control system, reactive power Power compensation, new energy (such as solar energy, wind power) and other fields have broad application prospects.
  • the advantages of the above rectifiers are realized by the double closed-loop linear control strategy and the nonlinear control strategy of the current inner loop and the voltage outer loop on the premise of the grid voltage balance.
  • the voltage source rectifier works in an unbalanced state (such as amplitude and phase imbalance, voltage dip, parametric imbalance, etc.), the presence of AC negative sequence current and negative sequence voltage, resulting in DC voltage appearing 2 4, ... subharmonics, 3, 5, ... harmonics will appear in the AC current, which will adversely affect the performance of the rectifier. In severe cases, it will cause a sharp deterioration of the entire system.
  • the traditional method is to control the AC terminal power of the voltage source type rectifier, which can theoretically eliminate the DC voltage fluctuation, but there is a complicated solution of the current command, and more variables are introduced to make the control system difficult to implement, so it is necessary to seek a kind of Simple and effective way to enhance DC side voltage stability control.
  • PI proportional integral
  • PR proportional resonance
  • the above methods have the following problems: 1) need to pass filters or delay algorithms Independent detection of positive and negative sequence current, there is steady state error or time delay; 2) using phase-locked loop to obtain synchronization signal, there is phase shift deviation and time delay; 3) PI or PR controller parameter design is more complicated, it is difficult to achieve Good current tracking accuracy and response speed; 4) The nonlinear controller has large parameter dependence, and the large amount of calculation results in poor real-time performance, which limits the use of the strategy.
  • Model predictive control can achieve accurate tracking of reference values due to its good dynamic characteristics. It has the advantages of small computational complexity and easy digital implementation. Therefore, a model predictive control method can be designed and applied to grid voltage imbalance control. Medium, thereby simplifying the system control algorithm and improving the control performance of the system.
  • the invention aims to solve the existing problems of voltage source type rectifier control when the grid voltage is unbalanced, and provides a simple and easy to implement model predictive current control method for enhancing DC side voltage stability control, which can ensure fast and accurate current in stationary coordinates. While tracking, it effectively eliminates the fluctuation of the DC side voltage and improves the power quality of the system. At the same time, it realizes the reliable grid-connected operation of the voltage source rectifier in the transient grid voltage imbalance, improving the dynamic and stability of the whole system.
  • the voltage source type rectifier model predictive control method for grid voltage unbalance proposed by the present invention adopts the following technical solutions:
  • a voltage source type rectifier model predictive control method for grid voltage imbalance comprising the following steps:
  • the three-phase grid voltages be e a , e b , and e c , respectively, and the three-phase grid currents are a , i b , and the DC side voltage is . , respectively transforming the three-phase grid voltage and current into a grid voltage e a , e p and current i a , ip in a two-phase stationary coordinate system via abc/ ⁇ coordinates;
  • Rectifier reference current calculation Let the PWM rectifier system average reactive power reference value av , ref be 0, calculate the positive and negative sequence components of the reference current in two-phase stationary coordinates by the following expression: ref mnea p
  • each switch state is evaluated by the value function g, and the switch state corresponding to the predicted current value that minimizes the value function is selected;
  • Z is the phase shift angle
  • ⁇ is the grid voltage angular frequency
  • the superscripts ⁇ and ⁇ represent the positive and negative sequence components, respectively;
  • e a (t - ⁇ ), et _ ) is the grid phase voltage in the two-phase ⁇ stationary coordinate system at t - time.
  • the control method proposed by the present invention proposes a method for enhancing the DC side voltage stability control by considering the power fluctuation on the incoming line inductance of the voltage source type rectifier under the unbalanced grid voltage, effectively solving the DC side voltage fluctuation problem.
  • the grid-connected operation of the voltage source rectifier under the unbalanced grid voltage is realized, the power quality of the system is improved, and the stability and reliability of the whole system are improved.
  • the invention applies the model predictive current control to the grid voltage imbalance control, realizes the fast and accurate tracking of the reference current, has the advantages of good dynamic characteristics, small calculation amount, easy digitization, and the like, and is suitable for the transient grid voltage. Balance the situation.
  • the control method of the invention is implemented in two-phase stationary coordinates, does not require a phase-locked loop to acquire the synchronization signal and positive and negative sequence decomposition of the current, and the control structure is simple and easier to implement, avoiding possible phase shift deviation and time delay. The problem is to improve the reliability of the system.
  • 1 is a topological structural diagram of a main circuit of a voltage type voltage source type rectifier
  • FIG. 2 is a schematic diagram of the principle of rapid decomposition of voltage positive and negative sequence components
  • Figure 3 is a flow chart of the model predictive current control algorithm
  • Figure 4 is a block diagram of the control system of the voltage source rectifier under unbalanced grid voltage.
  • the invention is a novel control strategy proposed for grid-connected operation of a voltage source type rectifier under the condition of grid voltage imbalance, and can effectively suppress the second harmonic component of the DC side voltage in a two-phase stationary coordinate system, simplifying the control system Algorithm to improve system response speed and reliability.
  • the following is a further description of the power model under unbalanced grid voltage, the separation of positive and negative voltage components, the calculation of reference current value, and the design of model prediction control algorithm.
  • the voltage source type rectifier acts as a power converter, and its main function is to obtain specific active power and reactive power from the grid side to meet the load demand. Therefore, the control of the input current and the DC side voltage by the voltage source type rectifier is actually an input. And control of output power. If the instantaneous active and reactive powers are quickly and efficiently controlled, the voltage source rectifier Can get good dynamic and static characteristics. Therefore, it is necessary to analyze the operating characteristics of the voltage source type rectifier under voltage imbalance from the power point of view, and then effectively determine and design the control method.
  • the power model of a voltage source rectifier under unbalanced grid voltage is described below.
  • Figure 1 is a schematic diagram of the main circuit topology of a voltage-type voltage source rectifier.
  • e a , e b , and ⁇ are the grid phase voltages; a , b , .
  • the vector equation of the voltage source rectifier in two-phase stationary coordinates is
  • the active power / 5 g and reactive power input on the grid side are composed of a direct current component and a double frequency component.
  • / ⁇ is the active power DC component
  • /3 ⁇ 4 is the secondary power component amplitude of the active power
  • v is the reactive power DC component
  • ⁇ and s g 2 are the reactive power double frequency component amplitude
  • the positive and negative sequence components of the grid voltage need to be separated in order to calculate the positive and negative sequence current reference values.
  • the common method is to use the trap.
  • the wave filter is separated from the quarter grid cycle delay method, and there is a problem of separation error and time delay. Therefore, the present invention adopts a fast positive and negative sequence component decomposition method, and the principle of positive and negative sequence component decomposition of the two-phase stationary coordinate system can be expressed as follows:
  • e a (t), e p (0 is the grid phase voltage in the two-phase ⁇ stationary coordinate system at time t;
  • e a (t- ), e t_ ⁇ ) is the grid phase in the two-phase ⁇ stationary coordinate system at t-time Voltage;
  • El ⁇ t), eUt) is the positive phase sequence of the grid phase voltage in the two-phase ⁇ stationary coordinate system at time t (t), e; ⁇ t) is the negative phase sequence of the phase voltage of the grid in the two-phase ⁇ stationary coordinate system at time t.
  • the specific embodiment can be represented by FIG. 2, and the grid voltage e a , ep in the two-phase ⁇ stationary coordinate system is obtained by sampling the grid side voltage through Clark transform, and then the grid positive sequence voltage and negative sequence are calculated by using equation (6). Voltage e;, e p n .
  • the algorithm can be completed in ( « ⁇ 1) sampling periods. When the sampling period of the system is very short, this separation method can improve the stability and response speed of the control system.
  • the control of the voltage source rectifier is mainly to suppress the active power fluctuation of the system to eliminate the second harmonic of the DC side voltage.
  • the system Under the influence of the degree of freedom of control, the system generally only controls v , ⁇ ⁇ and ⁇ 2 , but does not control G e2 and ft 2 .
  • the control system needs to select the appropriate power reference value to get the required reference current.
  • the calculation of the reference current in the present invention is implemented in a two-phase stationary coordinate system, so that the angular phase locking link and coordinate rotation transformation of the positive and negative sequence voltage vector of the grid are not needed, and the possible phase shift deviation is avoided. And time delay, which improves the reliability of the system.
  • the difference between the measured value and the actual sampled value is input to the PI controller.
  • the product of the PI controller output value and the DC voltage reference value is used as the system instantaneous active power reference value:
  • ⁇ , are the ratio and integral gain of the voltage outer loop PI regulator, respectively; [4 is the DC side voltage reference value.
  • the voltage source type rectifier is generally required to operate with a unit power factor, and the average reactive power reference value 3 ⁇ 4 ⁇ ⁇ is set to 0.
  • the input power of the AC end of the rectifier should be controlled instead of the input power of the control network side, that is, the / ⁇ sum should be equal to the active power reference value respectively. And 0, while making / 3 ⁇ 4, equal
  • d p ref is the positive sequence of the line current reference value in the positive sequence dq rotating coordinate system
  • d n ref is the negative sequence of the line current reference value in the negative sequence dq rotating coordinate system
  • the positive and negative sequence current reference values must be tracked without static tracking.
  • the current inner loop of PI, PR or some nonlinear controllers is generally used in the unbalanced control strategy, but the following problems exist: 1) The positive and negative sequence currents need to be independently detected by a filter or a delay algorithm, and there is a steady state error or Time delay; 2) Using phase-locked loop to obtain synchronization signal, there is phase shift deviation and time delay; 3) PI or PR controller parameter design is more complicated, it is difficult to achieve better current tracking accuracy and response speed; 4) The linear controller has large parameter dependence, and the large amount of calculation results in poor real-time performance.
  • the current inner loop control should be able to provide a relatively high bandwidth. , to ensure fast and accurate tracking of current, to minimize transient tracking time.
  • the model predictive control has good dynamic characteristics, it can realize accurate tracking of reference values, and has the advantages of small calculation amount and easy digital implementation. Therefore, the present invention proposes a model predictive control method and applies it to the grid voltage. In the unbalanced control, the system control algorithm can be simplified and the control performance of the system can be improved.
  • 33 ⁇ 4 + is the current predicted value at the time of the two-phase ⁇ stationary coordinate system
  • iM is the actual current sample value at the time of the two-phase ⁇ stationary coordinate system
  • e a (t k ), e p is the actual grid voltage sample value at the time of the two-phase ⁇ stationary coordinate system; u a (t k ) , ) is the AC end corresponding to the switch state applied during the first sampling period
  • U Ac (t k ) is the DC side voltage at time t k .
  • e a (t k+l ), e p (t, +1 ) is the predicted value of the grid voltage in the two-phase ⁇ stationary coordinate system at time t k+i . Since the sampling frequency is much larger than the grid frequency, the grid voltage can be considered One sample period remains unchanged, ie
  • a value function g is constructed to evaluate the voltage vectors of the rectifier, that is, the switching state corresponding to the current prediction value that minimizes the value function is selected in the next sampling period. This cycle allows for the ideal input current. Different control criteria will use different value functions g. Common methods use the sum of the absolute values of current errors as a function of value. The expression is:
  • ftref U is the current reference value in the two-phase ⁇ stationary coordinate system at the time of it +2 , and its value can be passed from the first few moments of the reference current value through Euler Second-order recursive method
  • 3 ⁇ 4ref ( +2 ) 33 ⁇ 4 re f ( ⁇ +l ) ⁇ 33 ⁇ 4 re f ) + 3 ⁇ 4ref )
  • the model is used to predict the current as shown in Figure 3.
  • the control algorithm can obtain the switching signals &, & and & of the three upper arms of the voltage source type rectifier to realize the breaking of the control power device.

Abstract

A model prediction control method for a voltage source-type rectifier when the voltage of a grid is unbalanced, comprising: (1) three-phase grid voltage and current are converted via abc/αβ coordinates into grid voltage and current in a two-phase static coordinate system; (2) a positive and negative sequence coordinate separation is performed on the grid voltage in the two-phase static coordinate system to acquire a positive sequence voltage and negative sequence voltage of the grid; (3) an active power reference value is calculated; (4) a current reference value of the rectifier in the two-phase static coordinate system is calculated; and, (5) a model prediction current control is performed to select the optimal switch state. The method, while ensuring rapid and accurate tracking of a current in two phases of static coordinates, effectively eliminates voltage fluctuations at an alternating current side, and improves the quality of electric power of the system.

Description

电网电压不平衡时电压源型整流器模型预测控制方法 技术领域  Voltage source type rectifier model predictive control method when grid voltage is unbalanced
本发明涉及一种在不平衡电网电压下电压源型整流器的控制方法， 属于功率变换器控制 领域。  The invention relates to a control method of a voltage source type rectifier under an unbalanced grid voltage, and belongs to the field of power converter control.
背景技术  Background technique
电压源型脉宽调制整流器具有网侧电压正弦化、 单位功率因素、 能量双向流动及恒定直 流电压控制的优点， 能够实现电能"绿色变换"， 因此在工业直流电源、 变频调速系统、 无功 功率补偿、 新能源 （如太阳能、 风力发电） 等领域有着广泛的应用前景。 上述整流器优点是 在假设电网电压平衡的前提下， 利用电流内环和电压外环的双闭环线性控制策略和非线性控 制策略实现的。 但在工程实际中， 电压源型整流器工作于不平衡状态 （如幅相不平衡、 电压 突降、 参数不平衡等）， 交流负序电流以及负序电压的存在， 导致直流电压中将出现 2、 4、 ... 次谐波， 交流电流中将出现 3、 5、 …次谐波， 对整流器的性能产生不良影响， 严重时会引起 整个系统的急剧恶化。  The voltage source type pulse width modulation rectifier has the advantages of grid side voltage sinusoidal, unit power factor, energy bidirectional flow and constant DC voltage control, which can realize "green conversion" of electric energy, so in industrial DC power supply, variable frequency speed control system, reactive power Power compensation, new energy (such as solar energy, wind power) and other fields have broad application prospects. The advantages of the above rectifiers are realized by the double closed-loop linear control strategy and the nonlinear control strategy of the current inner loop and the voltage outer loop on the premise of the grid voltage balance. However, in engineering practice, the voltage source rectifier works in an unbalanced state (such as amplitude and phase imbalance, voltage dip, parametric imbalance, etc.), the presence of AC negative sequence current and negative sequence voltage, resulting in DC voltage appearing 2 4, ... subharmonics, 3, 5, ... harmonics will appear in the AC current, which will adversely affect the performance of the rectifier. In severe cases, it will cause a sharp deterioration of the entire system.
目前国内外电网电压不平衡时电压源型整流器的控制策略， 主要是设法消除或者抑制网 侧电流的基波负序分量和有限次谐波分量以及直流电压中的谐波分量。 在忽略进线电抗器的 功率交换的情况下， 抑制网侧输出有功功率的波动可以保持直流侧电容电压恒定且无二倍频 波动； 当电压源型整流器应用在大功率场合时， 由于电力电子器件自身损耗的限制， 其开关 频率一般较低， 进线电抗器上的功率波动不能忽略， 此时若采用抑制网侧有功功率波动的控 制策略， 则电抗器上的有功功率波动需要直流侧功率波动来抵消， 造成直流侧电容电压波动 无法消除， 造成电容的频繁充放电， 严重时甚至影响整个系统的稳定运行。 目前传统的方法 是通过控制电压源型整流器交流端功率， 理论上可消除直流电压波动， 但是却存在电流指令 的求解复杂， 更多的变量引入使控制系统不易实现等， 因此有必要寻求一种简单有效的增强 直流侧电压稳定控制的方法。  At present, the control strategy of the voltage source type rectifier when the grid voltage is unbalanced at home and abroad is mainly to try to eliminate or suppress the fundamental negative sequence component and the finite harmonic component of the grid side current and the harmonic component in the DC voltage. In the case of neglecting the power exchange of the line reactor, suppressing the fluctuation of the active power of the grid side output can keep the DC side capacitor voltage constant and without double frequency fluctuation; When the voltage source type rectifier is applied in a high power occasion, due to power electronics The limitation of the device's own loss, its switching frequency is generally low, the power fluctuation on the line reactor can not be ignored. At this time, if the control strategy of suppressing the active power fluctuation on the grid side is adopted, the active power fluctuation on the reactor needs DC side power. The fluctuations are offset, causing the DC side capacitor voltage fluctuations to be eliminated, causing frequent charging and discharging of the capacitors, and even affecting the stable operation of the entire system in severe cases. At present, the traditional method is to control the AC terminal power of the voltage source type rectifier, which can theoretically eliminate the DC voltage fluctuation, but there is a complicated solution of the current command, and more variables are introduced to make the control system difficult to implement, so it is necessary to seek a kind of Simple and effective way to enhance DC side voltage stability control.
此外， 目前不平衡控制策略中一般采用比例积分（PI)、 比例谐振（PR)控制器或者一些 非线性控制器的电流内环， 上述方法存在以下问题： 1 )需要通过滤波器或延时算法独立检测 正负序电流， 存在稳态误差或者时间延迟； 2)采用锁相环获取同步信号， 存在相移偏差和时 间延迟； 3 ) PI或者 PR控制器的参数设计比较复杂， 很难实现较好的电流跟踪精度和响应速 度； 4) 非线性控制器参数依赖性大， 同时计算量大导致实时性差， 限制了该策略的使用等。 因此， 当电网电压发生暂态不平衡时， 为了能使电压源型整流器能稳定可靠运行， 对控制系 统的响应速度和精确跟踪等性能要求更高， 电流内环控制应能够提供一个相对高的带宽， 保 证对电流的快速精确跟踪， 尽可能地减少瞬态跟踪时间。 模型预测控制由于具有很好的动态 特性， 可以实现对参考值的精确跟踪， 具有计算量小， 易于数字化实现等优点， 因此可以设 计一种模型预测控制方法， 将其应用到电网电压不平衡控制中， 从而简化系统控制算法， 改 善系统的控制性能。  In addition, current imbalance control strategies generally use proportional integral (PI), proportional resonance (PR) controllers or current inner loops of some nonlinear controllers. The above methods have the following problems: 1) need to pass filters or delay algorithms Independent detection of positive and negative sequence current, there is steady state error or time delay; 2) using phase-locked loop to obtain synchronization signal, there is phase shift deviation and time delay; 3) PI or PR controller parameter design is more complicated, it is difficult to achieve Good current tracking accuracy and response speed; 4) The nonlinear controller has large parameter dependence, and the large amount of calculation results in poor real-time performance, which limits the use of the strategy. Therefore, when the grid voltage transient imbalance occurs, in order to enable the voltage source type rectifier to operate stably and reliably, the performance requirements of the control system such as response speed and precise tracking are higher, and the current inner loop control should be able to provide a relatively high Bandwidth, ensuring fast and accurate tracking of current, minimizing transient tracking time. Model predictive control can achieve accurate tracking of reference values due to its good dynamic characteristics. It has the advantages of small computational complexity and easy digital implementation. Therefore, a model predictive control method can be designed and applied to grid voltage imbalance control. Medium, thereby simplifying the system control algorithm and improving the control performance of the system.
发明内容 本发明目的在于解决电网电压不平衡时电压源型整流器控制的现有问题， 提供一种简单 易于实现的增强直流侧电压稳定控制的模型预测电流控制方法， 可以在静止坐标下保证对电 流快速精确跟踪的同时有效消除直流侧电压的波动， 改善系统的电能质量； 同时实现电压源 型整流器在暂态电网电压不平衡时的可靠并网运行， 提高整个系统的动态性和稳定性。 为了 实现上述目的， 本发明提出的电网电压不平衡时电压源型整流器模型预测控制方法， 采用以 下技术方案： Summary of the invention The invention aims to solve the existing problems of voltage source type rectifier control when the grid voltage is unbalanced, and provides a simple and easy to implement model predictive current control method for enhancing DC side voltage stability control, which can ensure fast and accurate current in stationary coordinates. While tracking, it effectively eliminates the fluctuation of the DC side voltage and improves the power quality of the system. At the same time, it realizes the reliable grid-connected operation of the voltage source rectifier in the transient grid voltage imbalance, improving the dynamic and stability of the whole system. In order to achieve the above object, the voltage source type rectifier model predictive control method for grid voltage unbalance proposed by the present invention adopts the following technical solutions:
一种电网电压不平衡时电压源型整流器模型预测控制方法， 包括下列步骤：  A voltage source type rectifier model predictive control method for grid voltage imbalance, comprising the following steps:
(1) 设三相电网电压分别为 ea、 eb、 ec, 三相电网电流分别为 a、 ib、 , 直流侧电压为 。， 分别将三相电网电压和电流经 abc/αβ坐标变换为两相静止坐标系下的电网电压 ea、 ep和电流 ia、 ip; (1) Let the three-phase grid voltages be e a , e b , and e c , respectively, and the three-phase grid currents are a , i b , and the DC side voltage is . , respectively transforming the three-phase grid voltage and current into a grid voltage e a , e p and current i a , ip in a two-phase stationary coordinate system via abc/αβ coordinates;
(2) 对两相静止坐标系下的电网电压 ea、ep进行正负序分量分离得到电网正序电压 (o、 ep p(o 和负序电压 (t)、 e;(t) ; (2) The positive and negative sequence components of the grid voltage e a , ep in the two-phase stationary coordinate system are separated to obtain the positive sequence voltage of the grid (o, e p p (o and negative sequence voltage (t), e; (t) ;
(3) 使用数字陷波器滤除实际直流电压 f/d。中存在的二次谐波干扰， 然后计算 f/d。与参考值 UAc ref之间的误差， 将此误差经过 PI调节器运算后转化为系统有功功率参考值
Figure imgf000004_0001
(3) Use the digital notch filter to filter out the actual DC voltage f/ d . The second harmonic interference present in, then calculate f / d . The error between the reference value U Ac ref and the error is converted into the system active power reference value by the PI regulator operation.
Figure imgf000004_0001
(4) 整流器参考电流计算： 令 PWM整流器系统平均无功功率参考值 av，ref为 0， 由下列表达式计算两相静止坐标下 的参考电流正、 负序分量： ref m n e ap (4) Rectifier reference current calculation: Let the PWM rectifier system average reactive power reference value av , ref be 0, calculate the positive and negative sequence components of the reference current in two-phase stationary coordinates by the following expression: ref mnea p
=  =
ref -n m  Ref -n m
'a.ref —m -n 'a.ref —m -n
'ftref n —m — ―  'ftref n —m — ―
2P av're ,f 2P av're ,f
m：  m:
、 llcoL  , llcoL
3[( )2 + ( )2 - «)2 - (e;f r 式中 、 epp为在两相 αβ静止坐标系下的电网正序相电压; 3[( ) 2 + ( ) 2 - «) 2 - (e; fr where ep p is the positive sequence voltage of the grid in the two-phase αβ stationary coordinate system;
、 e 为在两相 αβ静止坐标系下的电网负序相电压;  , e is the negative sequence voltage of the grid in the two-phase αβ stationary coordinate system;
Zf 'ref .ref为两相 αβ静止坐标系下电压源型正序电流参考值;  Zf 'ref .ref is a voltage source type positive sequence current reference value in a two-phase αβ stationary coordinate system;
?a,ref .ref为两相 αβ静止坐标系下电压源型负序电流参考值;  ?a, ref .ref is a voltage source type negative sequence current reference value in a two-phase αβ stationary coordinate system;
J为网侧进线滤波电感；  J is the network side incoming line filter inductor;
分别将上述参考电流的正序分 t和负序分量相加，得出两相 αβ静止坐标系下的系统电 参考值 Za,ref 、 ¾ref ； The positive sequence t and the negative sequence component of the above reference current are respectively added to obtain the system electrical reference values Z a, ref , 3⁄4ref in the two-phase αβ stationary coordinate system;
(5) 进行模型预测电流控制,方法如下: (a)根据当前 时刻检测的电网电压和电流， 由以下预测模型计算 tk+1时刻的电流值: (5) Perform model prediction current control as follows: (a) Calculate the current value at time t k+1 from the following prediction model based on the grid voltage and current detected at the current time:
Figure imgf000005_0001
Figure imgf000005_0001
式中， R为进线电感内阻； rs为采样周期； Where R is the internal resistance of the incoming inductor; r s is the sampling period;
iM、 是 时刻在两相 αβ静止坐标系下的实际电流值；  iM, is the actual current value at the time of the two-phase αβ stationary coordinate system;
ia(tM)、 zp¾+1)是 tk+1时刻在两相 αβ静止坐标系下的电流估算值； i a (t M ), z p 3⁄4 +1 ) is the current estimate at the time t k+1 in the two-phase αβ stationary coordinate system;
ea(tk)、 ep( 是 时刻在两相 αβ静止坐标系下的实际电网电压值； e a (t k ), e p (is the actual grid voltage value at the time of the two-phase αβ stationary coordinate system;
ua(tk), )是第 个采样周期内应用的开关状态所对应交流侧电压的 αβ分量，初始 时刻值可以设为 0; u a (t k ), ) is the αβ component of the AC side voltage corresponding to the switching state applied in the first sampling period, and the initial time value can be set to 0;
(b) 利用下式计算第) HI个采样周期内的每个开关状态所对应的交流侧电压 +1)、(b) Calculate the AC side voltage +1 ) corresponding to each switch state in the HIth sampling period using the following formula,
"D β lk+\ ， 即 "D β l k+\ , ie
Figure imgf000005_0002
Figure imgf000005_0002
式中， &、 sh, &为电压源型整流器三个上桥臂的开关状态； Where &, s h , & are the switching states of the three upper arms of the voltage source rectifier;
Uic(tk+l)是 tk+l时刻的直流侧电压； U ic (t k+l ) is the DC side voltage at time t k+l ;
(c) 由上述交流侧电压 Ma(U、 up(tk+l), 按照前述预测模型向前进一步预测 i+2时刻在 两相静止坐标系下的电流值 a(U、 tk+2)； (c) From the above-mentioned AC side voltage M a (U, u p (t k+l ), further predict the current value a (U, t k ) in the two-phase stationary coordinate system at the time i + 2 according to the aforementioned prediction model. +2 );
(d) 构造一个价值函数
Figure imgf000005_0003
(d) Construct a value function
Figure imgf000005_0003
式中， UU、 ftref(U是 it+2时刻电流参考值， 通过价值函数 g对每一个开关状态进行评 估， 选出使得价值函数最小的预测电流值所对应的开关状态； Where UU, ftref (U is the current reference value of it +2 ), each switch state is evaluated by the value function g, and the switch state corresponding to the predicted current value that minimizes the value function is selected;
(e) 根据步骤 （d) 中选出的开关状态， 对电压源型整流器三个上桥臂上的开关进行控 制， 实现整流器的稳定运行。 作为优选实施方式， 步骤（2) 中采用下式所示的分解法对电网电压 ea、 进行正、 负序 分量分离得到电网正序电压 (t)、 (t)和负序电压 (0、 e;(t) , 即 (t) =→a (t) -— ^[ep (t- )~ ep (t) cos γ] (e) According to the switch state selected in step (d), control the switches on the three upper arms of the voltage source rectifier to achieve stable operation of the rectifier. As a preferred embodiment, in step (2), the grid voltage e a , the positive and negative sequence components are separated by the decomposition method shown in the following formula to obtain the grid positive sequence voltage (t), (t) and negative sequence voltage (0, e;(t) , ie (t) =→ a (t) -^ ^[e p (t- )~ e p (t) cos γ]
2 2 sin ω  2 2 sin ω
(t) =→p (t) -—^- [ea (t - — ea (t) cos γ] (t) =→ p (t) -—^- [e a (t - — e a (t) cos γ]
2 2 sin ω
Figure imgf000006_0001
2 2 sin ω
Figure imgf000006_0001
式中， Z为相移角度； ω为电网电压角频率； 上标 ρ、 η分别代表正、 负序分量； Where Z is the phase shift angle; ω is the grid voltage angular frequency; the superscripts ρ and η represent the positive and negative sequence components, respectively;
ea (t)、 ep (t)为 t时刻两相 αβ静止坐标系下的电网相电压； e a (t), e p (t) is the grid phase voltage in the two-phase αβ stationary coordinate system at time t;
el (t)、 (t)为 t时刻两相 αβ静止坐标系下的电网正序相电压；  El (t), (t) is the positive sequence voltage of the grid in the two-phase αβ stationary coordinate system at time t;
(t)、 e; (t)为 t时刻两相 αβ静止坐标系下的电网负序相电压；  (t), e; (t) is the negative sequence voltage of the grid in the two-phase αβ stationary coordinate system at time t;
ea (t -^)、 e t _ )为 t - 时刻两相 αβ静止坐标系下的电网相电压。 e a (t -^), et _ ) is the grid phase voltage in the two-phase αβ stationary coordinate system at t - time.
ω ω ω  ω ω ω
本发明具有如下的技术效果：  The invention has the following technical effects:
1、本发明所提出的控制方法通过考虑在不平衡电网电压下电压源型整流器进线电感上的 功率波动， 提出了一个增强直流侧电压稳定控制的方法， 有效解决了直流侧电压波动问题， 同时实现电压源型整流器在不平衡电网电压下的并网运行， 改善系统的电能质量， 提高整个 系统的稳定性和可靠性。  1. The control method proposed by the present invention proposes a method for enhancing the DC side voltage stability control by considering the power fluctuation on the incoming line inductance of the voltage source type rectifier under the unbalanced grid voltage, effectively solving the DC side voltage fluctuation problem. At the same time, the grid-connected operation of the voltage source rectifier under the unbalanced grid voltage is realized, the power quality of the system is improved, and the stability and reliability of the whole system are improved.
2、本发明的控制方法采用了一种正负序分量快速分解法， 相比滤波器或者四分之一电网 周期延时算法进行正负序分离， 减少了分解误差和时间延迟问题， 提高了控制系统的稳定性 和响应速度， 特别适合于暂态电网不平衡情况。  2. The control method of the present invention adopts a fast decomposition method of positive and negative sequence components, which performs positive and negative sequence separation compared with a filter or a quarter grid periodic delay algorithm, which reduces the decomposition error and time delay problem, and improves the problem. The stability and response speed of the control system is particularly suitable for transient grid imbalances.
3、本发明将模型预测电流控制应用到电网电压不平衡控制中， 实现了对参考电流的快速 精确跟踪， 具有动态特性好、 计算量小、 易于数字化实现等优点， 适合于暂态电网电压不平 衡情况。  3. The invention applies the model predictive current control to the grid voltage imbalance control, realizes the fast and accurate tracking of the reference current, has the advantages of good dynamic characteristics, small calculation amount, easy digitization, and the like, and is suitable for the transient grid voltage. Balance the situation.
4、本发明的控制方法均在两相静止坐标下实现， 不需要锁相环获取同步信号以及电流的 正负序分解， 控制结构简单更易于实现， 避免了可能存在的相移偏差和时间延迟问题， 提高 了系统的可靠性。  4. The control method of the invention is implemented in two-phase stationary coordinates, does not require a phase-locked loop to acquire the synchronization signal and positive and negative sequence decomposition of the current, and the control structure is simple and easier to implement, avoiding possible phase shift deviation and time delay. The problem is to improve the reliability of the system.
附图说明  DRAWINGS
图 1是电压型电压源型整流器主电路拓扑结构图；  1 is a topological structural diagram of a main circuit of a voltage type voltage source type rectifier;
图 2是电压正负序分量快速分解法原理示意图；  2 is a schematic diagram of the principle of rapid decomposition of voltage positive and negative sequence components;
图 3是模型预测电流控制算法流程图；  Figure 3 is a flow chart of the model predictive current control algorithm;
图 4是不平衡电网电压下电压源型整流器的控制系统框图。  Figure 4 is a block diagram of the control system of the voltage source rectifier under unbalanced grid voltage.
具体实施方式  detailed description
下面结合附图和实施例对本发明做进一步详细说明。  The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
本发明是针对电网电压不平衡情况下电压源型整流器并网运行所提出的一种新型控制策 略， 可以在两相静止坐标系下实现直流侧电压二次谐波分量的有效抑制， 简化控制系统算法， 提高系统响应速度和可靠性。 以下将从不平衡电网电压下的功率模型、 电压正负序分量分离、 参考电流值计算、 模型预测控制算法设计等四方面作进一步说明。  The invention is a novel control strategy proposed for grid-connected operation of a voltage source type rectifier under the condition of grid voltage imbalance, and can effectively suppress the second harmonic component of the DC side voltage in a two-phase stationary coordinate system, simplifying the control system Algorithm to improve system response speed and reliability. The following is a further description of the power model under unbalanced grid voltage, the separation of positive and negative voltage components, the calculation of reference current value, and the design of model prediction control algorithm.
( 1 ) 电网电压不平衡下电压源型整流器的功率模型  (1) Power model of voltage source rectifier under grid voltage imbalance
电压源型整流器作为功率变换器， 其主要作用是从电网侧获得特定的有功功率和无功功 率以满足负载的需要， 因此电压源型整流器对输入电流以及直流侧电压的控制实际上是对输 入和输出功率的控制。 如果瞬时有功和无功功率得到了快速有效的控制， 电压源型整流器就 能获得良好的动静态特性。 因此有必要从功率角度方面来分析电压不平衡下电压源型整流器 的运行特性， 进而有效地确定和设计控制方法。 下面将介绍不平衡电网电压下电压源型整流 器的功率模型。 The voltage source type rectifier acts as a power converter, and its main function is to obtain specific active power and reactive power from the grid side to meet the load demand. Therefore, the control of the input current and the DC side voltage by the voltage source type rectifier is actually an input. And control of output power. If the instantaneous active and reactive powers are quickly and efficiently controlled, the voltage source rectifier Can get good dynamic and static characteristics. Therefore, it is necessary to analyze the operating characteristics of the voltage source type rectifier under voltage imbalance from the power point of view, and then effectively determine and design the control method. The power model of a voltage source rectifier under unbalanced grid voltage is described below.
图 1为电压型电压源型整流器主电路拓扑结构图， 图中 ea、 eb、 ^为电网相电压； a、 b、 。为交流侧相电流； ua、 uh, 为整流器交流侧相电压； ^为直流侧电压； J、 R为进线电 抗器及其内阻， Pg、 ^分别为网侧输入有功功率和交流侧输入有功功率。 电压源型整流器在 两相静止坐标下的矢量方程为 Figure 1 is a schematic diagram of the main circuit topology of a voltage-type voltage source rectifier. In the figure, e a , e b , and ^ are the grid phase voltages; a , b , . For AC side phase current; u a , u h , is the AC side voltage of the rectifier; ^ is the DC side voltage; J, R is the line reactor and its internal resistance, P g , ^ are the input power of the grid side and The active power is input to the AC side. The vector equation of the voltage source rectifier in two-phase stationary coordinates is
EaP =UaP+L^ + RIap (1) 式中， £αβ、 和 /αβ分别为电网电压、 整流器交流侧相电压和输入电流在两相 αβ静止 坐标系下的合成矢量。 E aP =U aP +L^ + RI ap (1) where £ α β, and / α β are the combined vectors of the grid voltage, the AC side voltage of the rectifier, and the input current in the two-phase αβ stationary coordinate system.
当电网电压不平衡时， 电网电压£^和电流 /αβ均含有正序分量、 负序分量和零序分量。 对于三相无中线系统， 可以不考虑零序分量， 此时在旋转坐标系中， 除了逆时针旋转的正序 分量外， 还包括顺时针旋转的负序分量， 则 £αβ、 以及 /αβ可以表示为 When the grid voltage is unbalanced, both the grid voltage £^ and the current/ α β contain a positive sequence component, a negative sequence component, and a zero sequence component. For a three-phase neutral line system, the zero sequence component can be disregarded. In this case, in the rotating coordinate system, in addition to the positive sequence component rotated counterclockwise, the negative sequence component rotated clockwise, then £αβ, and /αβ can Expressed as
< υαΡ = νι, + υι, =^( + Κ + j ） （2) < υ αΡ = νι, + υι, =^( + Κ + j ) (2)
, ρ = ¾ + ¾
Figure imgf000007_0001
+ e-JiUi(d n+j q n) 式中： 上标 ρ、 η分别代表正、 负序分量； 下标 d、 q分别代表旋转坐标系 d、 q轴分量； ω为电网电压的同步角速度。 , ρ = 3⁄4 + 3⁄4
Figure imgf000007_0001
+ e - JiUi ( d n +j q n ) where: the superscripts ρ and η represent the positive and negative sequence components respectively; the subscripts d and q represent the d and q axis components of the rotating coordinate system respectively; ω is the synchronization of the grid voltage Angular velocity.
因此当电网电压不平衡时， 网侧输入的复功率 S可以表示为  Therefore, when the grid voltage is unbalanced, the complex power S input on the grid side can be expressed as
Ss =Ea^ =Ps +iQs (3) S s =E a ^ =P s + iQ s (3)
将式 (2)代入式 (1)可得  Substituting equation (2) into equation (1)
Pe
Figure imgf000007_0002
+ Pslsm(2 ot) (4) P e
Figure imgf000007_0002
+ P s lsm(2 ot) (4)
¾ ϋ cos (2 ) + 2 sin (2 ) 3⁄4 ϋ cos (2 ) + 2 sin (2 )
式中，  In the formula,
Figure imgf000007_0003
Figure imgf000007_0003
电压源型整流器交流端输入功率可以表述为 = + P:2 cos {2cot) + P2 sin [lcot) The input power of the AC terminal of the voltage source rectifier can be expressed as = + P: 2 cos {2cot) + P 2 sin [lcot)
(5)  (5)
Qc = Ql + Qli c s (2 ) + Ql2 sin {2ωή Q c = Ql + Qli cs (2 ) + Ql 2 sin {2ωή
式中， In the formula,
P =I.
Figure imgf000008_0001
Figure imgf000008_0002
P = I.
Figure imgf000008_0001
Figure imgf000008_0002
=1.  =1.
由式 (4)可以看出， 电网电压不平衡时， 在正、 负序双旋转坐标系中， 网侧输入的有功功 率/5 g和无功功率 由直流分量和二倍频分量组成。 其中， /^为有功功率直流分量； 和/ ¾ 为有功功率的二倍频分量幅值； v为无功功率直流分量； ρ 和 s g 2为无功功率二倍频分量幅 值； 同理， 电压源型整流器交流端输入功率 和¾由类似的定义； ed p和 为电网正序电压 dq轴分量； ed n和 为电网负序电压 dq轴分量； 和 为交流端正序电压 dq轴分量； 和 为电网负序电压 dq轴分量； d p和 为交流端正序电流 dq轴分量； d n和 q n为交流端负序电流 dq轴分量。 It can be seen from equation (4) that when the grid voltage is unbalanced, in the positive and negative sequence double-rotation coordinate system, the active power / 5 g and reactive power input on the grid side are composed of a direct current component and a double frequency component. Where /^ is the active power DC component; and /3⁄4 is the secondary power component amplitude of the active power; v is the reactive power DC component; ρ and s g 2 are the reactive power double frequency component amplitude; The input power of the AC source of the voltage source rectifier is similarly defined by 3⁄4; e d p is the dq axis component of the positive sequence voltage of the grid; e d n is the dq axis component of the grid negative sequence voltage; and is the positive sequence voltage dq axis of the AC terminal Component; and is the grid negative sequence voltage dq axis component; d p and is the AC terminal positive sequence current dq axis component; d n and q n are the AC terminal negative sequence current dq axis component.
(2) 电网电压正、 负序分量分离  (2) Separation of positive and negative sequence components of grid voltage
当三相电网电压不平衡时， 特别是暂态不平衡情况， 为了实现对整流器输入电流的控制， 需要对电网电压进行正负序分量分离以便计算正负序电流参考值， 常用方法是使用陷波滤波 器和四分之一电网周期延时法进行分离， 此时就存在分离误差和时间延迟问题。 因此本发明 采用了一种快速正负序分量分解法， 其两相静止坐标系下的电压正、 负序分量分解原理可以 表示如下：  When the voltage of the three-phase grid is unbalanced, especially the transient imbalance, in order to control the input current of the rectifier, the positive and negative sequence components of the grid voltage need to be separated in order to calculate the positive and negative sequence current reference values. The common method is to use the trap. The wave filter is separated from the quarter grid cycle delay method, and there is a problem of separation error and time delay. Therefore, the present invention adopts a fast positive and negative sequence component decomposition method, and the principle of positive and negative sequence component decomposition of the two-phase stationary coordinate system can be expressed as follows:
1 γ 1 γ
( = -ea( ― ~ (t) cos γ] ( = -e a ( ― ~ (t) cos γ]
2 sin o  2 sin o
A- ea(t)cos ] (6)A- ea (t)cos ] (6)
n ω n ω
Figure imgf000008_0003
Figure imgf000008_0003
e;(t) = ep(t)-e;(t) 为相移角度； e;(t) = e p (t)-e; (t) is the phase shift angle;
ea(t)、 ep(0为 t时刻两相 αβ静止坐标系下的电网相电压； ea(t- )、 e t_^)为 t- 时刻两相 αβ静止坐标系下的电网相电压; e a (t), e p (0 is the grid phase voltage in the two-phase αβ stationary coordinate system at time t; e a (t- ), e t_^) is the grid phase in the two-phase αβ stationary coordinate system at t-time Voltage;
ω ω ω  ω ω ω
el{t)、 eUt)为 t时刻两相 αβ静止坐标系下的电网相电压正序分 (t)、 e;{t)为 t时刻两相 αβ静止坐标系下的电网相电压负序分量。 El{t), eUt) is the positive phase sequence of the grid phase voltage in the two-phase αβ stationary coordinate system at time t (t), e; {t) is the negative phase sequence of the phase voltage of the grid in the two-phase αβ stationary coordinate system at time t.
具体的实施方式可以用图 2表示， 通过采样网侧电压经过 Clark变换得到两相 αβ静止坐 标系下的电网电压 ea、 ep, 然后采用式 (6)计算得到电网正序电压 、 和负序电压 e；、 ep n。 该算法可以在《 («≥1 )个采样周期内完成， 当系统采样周期很短时， 这种分离方法可以提高 控制系统的稳定性和响应速度。 The specific embodiment can be represented by FIG. 2, and the grid voltage e a , ep in the two-phase αβ stationary coordinate system is obtained by sampling the grid side voltage through Clark transform, and then the grid positive sequence voltage and negative sequence are calculated by using equation (6). Voltage e;, e p n . The algorithm can be completed in («≥1) sampling periods. When the sampling period of the system is very short, this separation method can improve the stability and response speed of the control system.
( 3 ) 两相静止坐标系下的参考电流值计算  (3) Calculation of reference current value in two-phase stationary coordinate system
当三相电网电压不平衡时， 对电压源型整流器的控制主要是抑制系统有功功率波动以消 除直流侧电压的二次谐波。 受控制自由度的影响， 系统一般仅对 v、 βαν ^和 Λ2进行控 制， 而对 Ge2和 ft2不进行控制。控制系统需选择合适的功率参考值， 从而得到所需的参考电 流。 为了简化系统控制算法， 本发明中参考电流的计算均在两相静止坐标系下实现， 因此不 需要电网正负序电压矢量的角度锁相环节和坐标旋转变换， 避免了可能存在的相移偏差和时 间延迟， 提高了系统的可靠性。 When the voltage of the three-phase grid is unbalanced, the control of the voltage source rectifier is mainly to suppress the active power fluctuation of the system to eliminate the second harmonic of the DC side voltage. Under the influence of the degree of freedom of control, the system generally only controls v , βαν ^ and Λ 2 , but does not control G e2 and ft 2 . The control system needs to select the appropriate power reference value to get the required reference current. In order to simplify the system control algorithm, the calculation of the reference current in the present invention is implemented in a two-phase stationary coordinate system, so that the angular phase locking link and coordinate rotation transformation of the positive and negative sequence voltage vector of the grid are not needed, and the possible phase shift deviation is avoided. And time delay, which improves the reliability of the system.
与 、流侧负载有关，其 ¾T ¾il :、流侧 外环 PI调 得到， 即将  Related to the flow side load, its 3⁄4T 3⁄4il :, the flow side outer ring PI is adjusted,
考值与实际采样值相减后的差值输入 PI控制器， PI控制器输出值与直流电压参考值的乘积则 作为系统瞬时有功功率给定值：
Figure imgf000009_0001
The difference between the measured value and the actual sampled value is input to the PI controller. The product of the PI controller output value and the DC voltage reference value is used as the system instantaneous active power reference value:
Figure imgf000009_0001
式中， νρ、 ,分别为电压外环 PI调节器的比例和积分增益； [4为直流侧电压参考值。 另外 一般要求电压源型整流器单位功率因素运行， 此时平均无功功率参考值 ¾ν ^设为 0。 Where νρ , , are the ratio and integral gain of the voltage outer loop PI regulator, respectively; [4 is the DC side voltage reference value. In addition, the voltage source type rectifier is generally required to operate with a unit power factor, and the average reactive power reference value 3⁄4 ν ^ is set to 0.
在进线电抗器电感值较小条件下， 可以不考虑进线电抗器的功率波动， 认为 PC=PS， 因 此抑制网侧有功功率的波动， 则可以保持直流侧电容电压恒定且无二倍频波动。 当电压源型 整流器应用在大功率场合时， 其进线电感值相对较大， 电网电压发生不平衡时进线电抗器上 的功率波动不能忽略， 此时若采用抑制网侧有功功率波动的控制策略， 则电抗器上的有功功 率波动需要直流侧功率波动来抵消， 造成直流侧电压波动无法消除。 为了有效消除直流侧电 压的二倍频波动， 则需要考虑电抗器上的功率波动， 此时应该控制整流器交流端输入功率代 替控制网侧输入功率， 即应该使/^和 分别等于有功功率参考值和 0， 同时使/ ¾、 等于Under the condition that the inductance of the line reactor is small, the power fluctuation of the line reactor can be ignored, and P C =P S is considered . Therefore, the fluctuation of the active power on the grid side can be suppressed, and the DC side capacitor voltage can be kept constant and there is no difference. Multiplier fluctuations. When the voltage source type rectifier is applied in high power applications, the inductance of the incoming line is relatively large. When the grid voltage is unbalanced, the power fluctuation on the line reactor cannot be ignored. At this time, if the control of the active power fluctuation on the grid side is adopted, In the strategy, the active power fluctuation on the reactor needs to be offset by the DC side power fluctuation, which causes the DC side voltage fluctuation to be eliminated. In order to effectively eliminate the double frequency fluctuation of the DC side voltage, it is necessary to consider the power fluctuation on the reactor. At this time, the input power of the AC end of the rectifier should be controlled instead of the input power of the control network side, that is, the /^ sum should be equal to the active power reference value respectively. And 0, while making / 3⁄4, equal
0。 此时系统无功功率由于不可控， 仍然会有二倍频波动， 但其平均值为 0。 因此由式 (5)可得 直流侧电压无波动控制时在同步旋转坐标系下参考电流正负序分量表达式为 0. At this time, the system reactive power is still uncontrollable, and there will still be double frequency fluctuations, but the average value is 0. Therefore, the expression of the positive and negative sequence components of the reference current in the synchronous rotating coordinate system is obtained by the equation (5) when the DC side voltage is not fluctuating.
Figure imgf000009_0002
Figure imgf000009_0002
式中， Ddq = (u f + (ulf - {u -«)2≠ 0；Where D dq = (uf + (ulf - {u -«) 2 ≠ 0;
dp ref、 q p ref为在正序 dq旋转坐标系下线电流参考值的正序分 d n ref、 q n ref为在负序 dq旋转坐标系下线电流参考值的负序分 d p ref , q p ref is the positive sequence of the line current reference value in the positive sequence dq rotating coordinate system d n ref , q n ref is the negative sequence of the line current reference value in the negative sequence dq rotating coordinate system
设坐标旋转变换矩阵 Mdq+→aP P ½^_→ 为 Let coordinate rotation transformation matrix M dq+→aP P 1⁄2^_ →
cos^p -sin^1 Cos^ p -sin^ 1
M dq+→a + (10) M dq+ →a + (10)
sin^p cos^p cos θη sin Θ1 Sin^ p cos^ p cos θ η sin Θ 1
M dq—— * β- (11)  M dq -- * β- (11)
-sin^" cos<9'  -sin^" cos<9'
式中， 和^1分别为网侧电压矢量正负序旋转角度。则式 (8)和式 (9)两边同时乘以矩阵 Mdq+→aP_ 和 Mdq_→ap_， 则可得两相 αβ静止坐标系下的参考电流正负序分量表达式 In the formula, and ^ 1 are the positive and negative sequence rotation angles of the grid side voltage vector, respectively. Then, when both sides of equations (8) and (9) are multiplied by the matrices M dq+→aP _ and M dq _ →a p_, the positive and negative sequence components of the reference current in the two-phase αβ stationary coordinate system can be obtained.
(12)(12)
Figure imgf000010_0002
Figure imgf000010_0003
Figure imgf000010_0002
Figure imgf000010_0003
Figure imgf000010_0001
式中， n = (\ - ^\ - A ( Lm)2 \ l2 L。 从式 (16)、 式 (17)可以看出， 在考虑电抗器上的功率波动后， 参考电流正负序分量的计算 中含有两部分， 从网侧输入功率的角度来看， 第一部分可视作提供直流侧负载所需的平均有 功功率， 第二部分可视作补偿电抗器上吸收的有功功率波动。 因此该控制方法可以很好地控 制整流器交流端的输入功率恒定， 保证直流侧电压稳定且无二倍频波动。 同时可以发现， 在 实际应用中， 由于在电感上的压降并不大， 系统功率因素近似等于 1， 可以满足应用需求。
Figure imgf000010_0001
Where n = (\ - ^\ - A ( Lm) 2 \ l2 L. From equations (16) and (17), it can be seen that after considering the power fluctuations on the reactor, the reference current positive and negative sequence components The calculation contains two parts. From the perspective of the input power of the grid side, the first part can be regarded as the average active power required to provide the DC side load, and the second part can be regarded as the active power fluctuation absorbed on the compensation reactor. The control method can well control the input power of the AC end of the rectifier to be constant, and ensure that the DC side voltage is stable and has no double frequency fluctuation. At the same time, it can be found that, in practical applications, since the voltage drop on the inductor is not large, the system power factor Approximate to 1, to meet the needs of the application.
(4) 模型预测控制算法设计  (4) Model predictive control algorithm design
要实现电网不平衡时电压源型整流器直流侧电压的无纹波控制， 则必须对求得的正负序 电流参考值进行无静差跟踪控制。 目前不平衡控制策略中一般采用 PI、 PR或者一些非线性控 制器的电流内环，但是存在以下问题： 1 )需要通过滤波器或延时算法独立检测正、负序电流， 存在稳态误差或者时间延迟； 2) 采用锁相环获取同步信号， 存在相移偏差和时间延迟； 3 ) PI或者 PR控制器的参数设计比较复杂， 很难实现较好的电流跟踪精度和响应速度； 4)非线 性控制器参数依赖性大， 同时计算量大导致实时性差等。 当电网电压发生暂态不平衡时， 为 了能使电压源型整流器能稳定可靠运行，对控制系统的响应速度和精确跟踪等性能要求更高， 因此电流内环控制应能够提供一个相对高的带宽， 保证对电流的快速精确跟踪， 尽可能地减 少瞬态跟踪时间。 模型预测控制由于具有很好的动态特性， 可以实现对参考值的精确跟踪， 具有计算量小， 易于数字化实现等优点， 因此本发明提出了一种模型预测控制方法， 并将其 应用到电网电压不平衡控制中， 从而可以简化系统控制算法， 改善系统的控制性能。  To achieve ripple-free control of the DC-side voltage of the voltage source rectifier when the grid is unbalanced, the positive and negative sequence current reference values must be tracked without static tracking. At present, the current inner loop of PI, PR or some nonlinear controllers is generally used in the unbalanced control strategy, but the following problems exist: 1) The positive and negative sequence currents need to be independently detected by a filter or a delay algorithm, and there is a steady state error or Time delay; 2) Using phase-locked loop to obtain synchronization signal, there is phase shift deviation and time delay; 3) PI or PR controller parameter design is more complicated, it is difficult to achieve better current tracking accuracy and response speed; 4) The linear controller has large parameter dependence, and the large amount of calculation results in poor real-time performance. When the grid voltage is transiently unbalanced, in order to enable the voltage source rectifier to operate stably and reliably, the response speed and precise tracking of the control system are required to be higher. Therefore, the current inner loop control should be able to provide a relatively high bandwidth. , to ensure fast and accurate tracking of current, to minimize transient tracking time. Because the model predictive control has good dynamic characteristics, it can realize accurate tracking of reference values, and has the advantages of small calculation amount and easy digital implementation. Therefore, the present invention proposes a model predictive control method and applies it to the grid voltage. In the unbalanced control, the system control algorithm can be simplified and the control performance of the system can be improved.
常见的模型预测控制方式为建立一个系统离散化预测模型， 然后构造一个价值函数， 在 每一个采样周期内， 通过预测模型对每一个开关电压矢量进行评估， 使价值函数最小对应的 开关矢量在下一个采样周期被采用， 从而实现最优跟踪控制。  A common model predictive control method is to establish a system discretization prediction model, and then construct a value function. In each sampling period, each switching voltage vector is evaluated by the prediction model, so that the minimum value of the switching vector of the value function is next. The sampling period is employed to achieve optimal tracking control.
在一个采样周 7 内， 根据式 (1)可得电压源型整流器的离散化预测模型为  In one sampling week 7, the discretization prediction model of the voltage source rectifier is obtained according to equation (1).
Figure imgf000011_0001
Figure imgf000011_0001
式中， L、 R为进线电感及其电阻； 7；为采样周期。Where L and R are the incoming inductance and its resistance; 7; is the sampling period.
α¾+,) 是 时刻在两相 αβ静止坐标系下的电流预测值； iM、 是 时刻在两相 αβ静止坐标系下的实际电流采样值； 33⁄4 + ,) is the current predicted value at the time of the two-phase αβ stationary coordinate system; iM, is the actual current sample value at the time of the two-phase αβ stationary coordinate system;
ea (tk)、 ep( 是 时刻在两相 αβ静止坐标系下的实际电网电压采样值； ua (tk) , )是第 个采样周期内应用的开关状态所对应的交流端电压在两相静 止坐标系下的 αβ分量， 其值可以由下式求得： (tk ) = -UAc (tk )[Sa - - (Sh - Sc )] 式中， &、 Sh, Se为电压源型整流器三个上桥臂的开关状态 （共有 8种开关状态）； e a (t k ), e p (is the actual grid voltage sample value at the time of the two-phase αβ stationary coordinate system; u a (t k ) , ) is the AC end corresponding to the switch state applied during the first sampling period The αβ component of the voltage in a two-phase stationary coordinate system can be obtained by the following equation: (t k ) = -U Ac (t k )[S a - - (S h - S c )] Where, &, S h , S e are the switching states of the three upper arms of the voltage source rectifier (a total of 8 switching states);
UAc (tk )是 tk时刻的直流侧电压。 U Ac (t k ) is the DC side voltage at time t k .
在实际控制系统中， 通常会存在计算时间和控制延时的影响， 为了提高模型预测控制器 的性能， 须进行延时补偿。假定被选择的开关状态在第 A+1个采样周期应用， 必须去预测 采样时刻的电流。 因此需要将式 (18)向前推算一步， 可以得到如下预测模型 tk+2 ) =In the actual control system, there is usually the influence of calculation time and control delay. In order to improve the performance of the model prediction controller, delay compensation is required. Assuming that the selected switch state is applied during the A+1th sampling period, the current at the sampling instant must be predicted. Therefore, we need to calculate equation (18) forward one step, and we can get the following prediction model t k+2 ) =
Figure imgf000012_0001
Figure imgf000012_0001
式中， iaD、 (U是 时刻在两相 αβ静止坐标系下的电流预测值； Where i a D, (U is the current predicted value at the time of the two-phase αβ stationary coordinate system;
ea(tk+l)、 ep(t,+1)是 tk+i时刻在两相 αβ静止坐标系下的电网电压预测值， 由于采样频率 远大于电网频率， 可认为电网电压在一个采样周期内保持不变， 即e a (t k+l ), e p (t, +1 ) is the predicted value of the grid voltage in the two-phase αβ stationary coordinate system at time t k+i . Since the sampling frequency is much larger than the grid frequency, the grid voltage can be considered One sample period remains unchanged, ie
(tM), (U是第 A+l个采样周期内预测的开关状态所对应的交流端电压在两相静 止坐标系下的 αβ分量，其值可以根据 tk+1时刻的直流侧电压 。 及开关状态 &、 &和 & (共 8种开关状态)通过式 (19)求得。 (t M ), (U is the αβ component of the AC terminal voltage corresponding to the predicted switching state in the A+1 sampling period in the two-phase stationary coordinate system, and the value can be based on the DC side voltage at time t k+1 And the switch states &, &, & (a total of 8 switch states) are obtained by equation (19).
当 it+2时刻的电流被预测后， 构造一个价值函数 g去评估整流器各个电压矢量， 即选择 使价值函数最小的电流预测值所对应的开关状态在下一个采样周期被采用。 如此循环， 从而 获得理想的输入电流。 不同的控制标准将采用不同的价值函数 g， 常见方法采用电流误差的 绝对值之和作为价值函数， 其表达式为： When the current at time +2 is predicted, a value function g is constructed to evaluate the voltage vectors of the rectifier, that is, the switching state corresponding to the current prediction value that minimizes the value function is selected in the next sampling period. This cycle allows for the ideal input current. Different control criteria will use different value functions g. Common methods use the sum of the absolute values of current errors as a function of value. The expression is:
S ( +2 ( +2 ( +2 ( +2 )| (21)  S ( +2 ( +2 ( +2 ( +2 )| (21)
式中， ia，ief(tk+2) 、 ftref(U是 it+2时刻在两相 αβ静止坐标系下的电流参考值， 其值可以由前 几个时刻的参考电流值通过欧拉二阶递推法求得了， 即Where i a , ief (t k+2 ), ftref (U is the current reference value in the two-phase αβ stationary coordinate system at the time of it +2 , and its value can be passed from the first few moments of the reference current value through Euler Second-order recursive method
,ref ( +2 ) = 3Za,ref (¾+ι )― 3a ef (tk ) + Za,ref (jk― ) , ref ( +2 ) = 3Z a , ref (3⁄4+ι ) - 3 a ef (t k ) + Z a , ref (j k ― )
¾ref ( +2 ) = 3¾ref (^+l )― 3¾ref ) + ¾ref ) 3⁄4ref ( +2 ) = 33⁄4 re f (^+l )― 33⁄4 re f ) + 3⁄4ref )
式中， ,ref(im；)、 β,π^ίπθ为 时刻两相 αβ静止坐标系下的电流参考值值； Where ref (im;), β, π^ίπθ are the current reference values in the two-phase αβ stationary coordinate system at the moment;
iaM、 ref(i 为 时刻两相 αβ静止坐标系下的电流参考值；iaM, ref (i is the current reference value in the two-phase αβ stationary coordinate system at the moment;
a,ref( -l), ^ef^W)为 时刻两相 θ 静止坐标系下的电流参考值。  a, ref( -l), ^ef^W) is the current reference value in the two-phase θ stationary coordinate system at the moment.
根据以上的分析， 模型预测控制的实施可以用图 3所示的算法流程图表示：  Based on the above analysis, the implementation of the model predictive control can be represented by the algorithm flow chart shown in Figure 3:
(a) 首先采集 h时刻的三相电流 i(tk)、 三相电网电压 ¾ 以及直流侧电压 U ' (a) First collect the three-phase current i(tk) at time h, the three-phase grid voltage 3⁄4, and the DC-side voltage U '
(b) 应用上一时刻计算的开关状态 S{tk、， 通过式 (18)所示的预测模型去估算 tk+l时刻的 电流值 (im); (b) applying the switching state S{t k , calculated at the previous moment, using the prediction model shown in equation (18) to estimate the current value (im) at time t k+1 ;
(c) 分别使用 8种开关状态 （&、 &和 &)， 以及式 (19)和式 (20)所示的预测模型， 进一 步计算出 tk+1时刻的 8种电流预测值 i(tk+2); (c) Using eight kinds of switching states (&, &, and), and the prediction models shown in equations (19) and (20), respectively, to calculate the eight current prediction values i at t k+1 (t) k+2 );
(d) 构造一个如式 (21)所示的价值函数 g并计算其 8种结果 &， 选择使价值函数值最小 的电流预测值所对应的开关状态 在下一时刻被采用， 如此循环进行电流的精确跟踪控 制。 (d) Construct a value function g as shown in equation (21) and calculate its eight results & , and select the switch state corresponding to the current prediction value that minimizes the value of the value function to be used at the next moment, thus circulating the current. Precise tracking control System.
综上所述， 本发明所提出的控制方法的最佳实施方式可以系统地表示为图 4， 具体包括 以如下步骤：  In summary, the preferred embodiment of the control method proposed by the present invention can be systematically represented as FIG. 4, and specifically includes the following steps:
1) 采用电压传感器和电流传感器分别检测三相电网电压 ea、 eh, ee和网侧三相输入电流 ib、 , 分别经 abc-αβ坐标变换模块得到两相静止坐标系下的电网电压 ea、 和输入电流1) Using the voltage sensor and the current sensor to detect the three-phase grid voltage e a , e h , e e and the grid side three-phase input current i b , respectively, and obtain the grid under the two-phase stationary coordinate system via the abc-αβ coordinate transformation module respectively. Voltage e a , and input current
4、 ψ, 4, Hey,
2) 将步骤 (1)中的电网电压 ea、 通过图 2所示的快速正负序分量分解法， 得到在两相静 止坐标系下的电网正序电压 、 和负序电压 e:；、 e; -, 2) taking the grid voltage e a in the step (1) and the fast positive and negative sequence component decomposition method shown in FIG. 2 to obtain the grid positive sequence voltage and the negative sequence voltage e: in the two-phase stationary coordinate system; e; -,
3) 采用电压传感器检测直流侧电容电压 Udc， 使用数字陷波器滤除其二次谐波分量， 再 计算直流参考电压 f/de,ref与滤波后的 [4的差值， 经过 PI控制器的输出值与滤波后直流电压 f/dc的乘积作为直流侧输出的参考有功功率 ， 此时参考无功功率设为 0。 3) Using the voltage sensor to detect the DC side capacitor voltage U dc , use the digital notch filter to filter out the second harmonic component, and then calculate the DC reference voltage f / de , ref and the filtered [4 difference, after PI control The product of the output value of the device and the filtered DC voltage f/ dc is used as the reference active power of the DC side output. At this time, the reference reactive power is set to zero.
4) 由步骤 (3)中的两相静止坐标下的电网正序电压 、 ep p和负序电压 e：;、 e; , 以及步骤 (2)中得到的平均参考功率7^^和0„^， 通过式 (20)、 式 (21)所示的参考电流计算方法， 计算 两相静止坐标系下的参考电流 ,ref、 P,ref; 4) The grid positive sequence voltage, e p p and negative sequence voltage e:;, e; and the average reference power 7^^ and 0 obtained in step (2) from the two-phase stationary coordinates in step (3) „^, by the reference current calculation method shown in equations (20) and (21), calculate the reference current in two-phase stationary coordinate system, re f, P , ref;
5) 由步骤 (1)中的电网电压 ea、 和输入电流 、 步骤 (4)中的电流参考值 ,ref、 ref 以及直流侧电压 f/dc，采用如图 3所示的模型预测电流控制算法，可以得到电压源型整流器三 个上桥臂的开关信号 &、 &和&， 实现控制功率器件的开断。 5) From the grid voltage e a in step (1), and the input current, the current reference value in step (4), ref , re f and the DC side voltage f / dc , the model is used to predict the current as shown in Figure 3. The control algorithm can obtain the switching signals &, & and & of the three upper arms of the voltage source type rectifier to realize the breaking of the control power device.
综上所述， 本发明的控制方法在电网电压不平衡情况下， 可保证对电流快速精确跟踪的 同时有效消除直流侧电压波动， 改善系统的电能质量， 同时可实现电压源型整流器在暂态电 网电压不平衡时的可靠并网运行。所提的控制系统算法简单， 仅需在两相静止坐标系下实现， 无坐标旋转变换、 锁相环以及电流的正负序分解， 减少了控制系统的时间延迟和稳态误差， 提高了整个系统的动态性、 稳定性和可靠性。  In summary, the control method of the invention can ensure the rapid and accurate tracking of the current while effectively eliminating the DC side voltage fluctuation, improving the power quality of the system, and realizing the voltage source type rectifier in the transient state. Reliable grid operation when the grid voltage is unbalanced. The proposed control system has simple algorithm and only needs to be realized in two-phase stationary coordinate system. There is no coordinate rotation transformation, phase-locked loop and positive and negative sequence decomposition of current, which reduces the time delay and steady-state error of the control system and improves the whole. System dynamics, stability and reliability.

Claims

权利要求 Rights request
1. 一种电网电压不平衡时电压源型整流器模型预测控制方法， 其特征在于， 包括下列步骤：A voltage source type rectifier model predictive control method for grid voltage imbalance, characterized in that it comprises the following steps:
(1) 设三相电网电压分别为 ea、 eb、 ec, 三相电网电流分别为 a、 ib、 , 直流侧电压为 。， 分别将三相电网电压和电流经 abc/αβ坐标变换为两相静止坐标系下的电网电压 ea、 ep和电流 4、 ψ, (1) Let the three-phase grid voltages be e a , e b , and e c , respectively, and the three-phase grid currents are a , i b , and the DC side voltage is . , respectively, transforming the three-phase grid voltage and current into a grid voltage e a , e p and current 4 , ψ under a two-phase stationary coordinate system via abc/αβ coordinates,
(2)对两相静止坐标系下的电网电压 ea、ep进行正负序分量分离得到电网正序电压 (o、 ep p(o 和负序电压 (t)、 e;(t) ; (2) The positive and negative sequence components of the grid voltages e a and ep in the two-phase stationary coordinate system are separated to obtain the positive sequence voltage of the grid (o, e p p (o and negative sequence voltage (t), e; (t) ;
(3) 使用数字陷波器滤除实际直流电压 f/d。中存在的二次谐波干扰， 然后计算 f/d。与参考值 f/dcref之间的误差， 将此误差 ^过 PI调节器运算后转化为系统有功功率参考值
Figure imgf000014_0001
(3) Use the digital notch filter to filter out the actual DC voltage f/ d . The second harmonic interference present in, then calculate f / d . The error between the reference value f/ dcref and the error is converted into the system active power reference value after the PI regulator operation
Figure imgf000014_0001
(4) 整流器参考电流计算： 令电压源型整流器系统平均无功功率参考值 0av,ref为 0， 由下列表达式计算两相静止坐标 下的参考电流正、 负序分量： ref m n e (4) Rectifier reference current calculation: Let the voltage source rectifier system average reactive power reference value 0 av , ref be 0, calculate the positive and negative sequence components of the reference current in two-phase stationary coordinates by the following expression: ref mne
= ap = a p
ref -n m
Figure imgf000014_0002
Ref -nm
Figure imgf000014_0002
P，ref —  P, ref —
2P ； ref 2P ; ref
m： n： [\-^\-4( Lm)2\l2 L m: n: [\-^\-4( Lm) 2 \l2 L
3[«)2+ )2 -«) -( ) 3[«) 2 + ) 2 -«) -( )
式中 el、 ep p为在两相 αβ静止坐标系下的电网正序相电压; Where el, e p p are the positive sequence voltages of the grid in the two-phase αβ stationary coordinate system;
为在两相 αβ静止坐标系下的电网负序相电压;  The negative sequence voltage of the grid in the two-phase αβ stationary coordinate system;
ref 为两相 αβ静止坐标系下整流器正序电流参考值;  Ref is the reference value of the rectifier positive sequence current in the two-phase αβ stationary coordinate system;
ref 为两相 αβ静止坐标系下整流器负序电流参考值;  Ref is the reference value of the rectifier negative sequence current in the two-phase αβ stationary coordinate system;
J为网侧进线滤波电感;  J is the network side incoming line filter inductor;
分别将上述参考电流的正序分  Positive sequence of the above reference current
参考值 a ref .ref (5) 进行模型预测电流控制,方法如下: Reference value a ref .ref (5) Perform model prediction current control as follows:
(a)根据当前 时刻检测的电网电压和电流， 由以下预测模型计算 tk+ 时刻的电流值:
Figure imgf000015_0001
(a) Calculate the current value at time t k+ from the following prediction model based on the grid voltage and current detected at the current time:
Figure imgf000015_0001
式中， R为进线电感内阻； rs为采样周期； Where R is the internal resistance of the incoming inductor; r s is the sampling period;
iM、 是 it时刻在两相 αβ静止坐标系下的实际电流值；  iM, is the actual current value of it at the time of the two-phase αβ stationary coordinate system;
ia(tk+l)、 /p¾+1)是 tk+1时刻在两相 αβ静止坐标系下的电流估算值； i a (t k+l ), / p 3⁄4 +1 ) is the current estimation value in the two-phase αβ stationary coordinate system at time t k+1 ;
ea(tk)、 ep( 是 时刻在两相 αβ静止坐标系下的实际电网电压值； e a (t k ), e p (is the actual grid voltage value at the time of the two-phase αβ stationary coordinate system;
ua(tk), Μρ )是第 个采样周期内应用的开关状态所对应交流侧电压的 αβ分量，初始 时刻值可以设为 0; u a (t k ), Μ ρ ) is the αβ component of the AC side voltage corresponding to the switching state applied in the first sampling period, and the initial time value can be set to 0;
(b) 利用下式计算第) HI个采样周期内的每个开关状态所对应的交流侧电压 +1)、(b) Calculate the AC side voltage +1 ) corresponding to each switch state in the HIth sampling period using the following formula,
"D， 即"D, ie
=1  =1
式中， &、 sh, &为电压源型整流器三个上桥臂的开关状态； Where &, s h , & are the switching states of the three upper arms of the voltage source rectifier;
UAc(tk+l)是 tk+1时刻的直流侧电压； U Ac (t k+l ) is the DC side voltage at time t k+1 ;
(c) 由上述交流侧电压 )、 up(tk+l), 按照前述预测模型向前进一步预测 i+2时刻在 两相静止坐标系下的电流值 a(U、 i,(tk+2)； (c) From the above-mentioned AC side voltage), u p (t k+l ), further predict the current value a (U, i, (t k ) in the two-phase stationary coordinate system at i + 2 time according to the aforementioned prediction model. +2 );
(d) 构造一个价值函数  (d) Construct a value function
S -卜 ifk+2 - ( +2 ( +2 ( +2 ) S - Bu ifk+2 - ( +2 ( +2 ( +2 )
式中， UU、 ftref(U是 it+2时刻电流参考值， 通过价值函数 g对每一个开关状态进行评 估， 选出使得价值函数最小的预测电流值所对应的开关状态； Where UU, ftref (U is the current reference value of it +2 ), each switch state is evaluated by the value function g, and the switch state corresponding to the predicted current value that minimizes the value function is selected;
(e) 根据步骤 （d) 中选出的开关状态， 对电压源型整流器三个上桥臂上的开关进行控 制， 实现整流器的稳定运行。  (e) According to the switch state selected in step (d), control the switches on the three upper arms of the voltage source rectifier to achieve stable operation of the rectifier.
2. 根据权利要求 1所述的电网电压不平衡时电压源型整流器模型预测控制方法，其特征在于， 步骤（2) 中采用下式所示的分解法对电网电压 ea、 进行正、 负序分量分离得到电网正序电 压 (t)、 (t)和负序电压 (t)、 e t) , 即 ( ) = -ea{t) [e -—)-e )cosy]
Figure imgf000015_0002
Figure imgf000016_0001
2. The voltage source type rectifier model predictive control method according to claim 1, wherein in step (2), the grid voltage e a is positively and negatively determined by a decomposition method represented by the following formula: The sequence component is separated to obtain the positive sequence voltage (t), (t) and negative sequence voltage (t), et) of the grid, ie ( ) = -e a {t) [e -—)-e )cosy]
Figure imgf000015_0002
Figure imgf000016_0001
， Z为相移角度； ω为电网电压角频率； 上标 ρ、 η分别代表正、 负序分 ea (t)、 ep (t)为 t时刻两相 αβ静止坐标系下的电网相电压； , Z is the phase shift angle; ω is the grid voltage angular frequency; the superscript ρ, η represent the positive and negative sequence points e a (t), e p (t) is the grid phase of the two-phase αβ stationary coordinate system at time t Voltage;
el (t)、 (t)为 t时刻两相 αβ静止坐标系下的电网正序相电压；  El (t), (t) is the positive sequence voltage of the grid in the two-phase αβ stationary coordinate system at time t;
(t)、 e; (t)为 t时刻两相 αβ静止坐标系下的电网负序相电压； ea(t~-)^ e t_^)为 t- 时刻两相 αβ静止坐标系下的电网相电压。 (t), e; (t) is the negative sequence voltage of the grid in the two-phase αβ stationary coordinate system at time t; e a (t~-)^ e t_^) is the t-time two-phase αβ stationary coordinate system Grid phase voltage.
ω ω ω  ω ω ω
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CN113890090B (en) * 2021-09-29 2023-09-01 华中科技大学 VSC converter model predictive control method and system considering unbalanced filter inductance
CN114336660B (en) * 2021-12-27 2024-04-12 江苏师范大学 UPQC direct current prediction control method based on power angle
CN114710055B (en) * 2022-04-26 2022-10-28 南京理工大学 Two-parallel power converter model prediction control method based on finite set single vector
CN115967127B (en) * 2022-12-14 2024-02-23 南通国轩新能源科技有限公司 Direct power control system and method based on grid-connected inverter power prediction model
CN116865532B (en) * 2023-09-05 2023-11-24 国网山西省电力公司临汾供电公司 Control method of AC-DC converter adopting model predictive control
CN117254704B (en) * 2023-09-22 2024-04-19 中南大学 Grid-connected voltage type rectifier frequency division analog resistance control method under unbalanced power grid

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101615854A (en) * 2009-07-29 2009-12-30 北京交通大学 The control method of three-phase voltage type PWM rectifier under unbalance voltage of power grid
CN101951174A (en) * 2010-09-11 2011-01-19 天津大学 Constant-frequency direct power control method for PWM converter under condition of power grid voltage imbalance
CN102655332A (en) * 2012-04-28 2012-09-05 北方工业大学 Method for controlling network side rectifier of brushless double-feed wind-driven generator under unbalanced electric network
CN102694394A (en) * 2012-04-28 2012-09-26 北方工业大学 Method and system for controlling current of grid-side converter of wind driven generator under unbalanced power grid condition

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009016113A1 (en) * 2007-07-27 2009-02-05 Abb Research Ltd Controlling a power system
CN102163947B (en) * 2011-04-14 2013-02-13 天津大学 Commutation torque ripple suppression method for permanent magnet brushless DC motor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101615854A (en) * 2009-07-29 2009-12-30 北京交通大学 The control method of three-phase voltage type PWM rectifier under unbalance voltage of power grid
CN101951174A (en) * 2010-09-11 2011-01-19 天津大学 Constant-frequency direct power control method for PWM converter under condition of power grid voltage imbalance
CN102655332A (en) * 2012-04-28 2012-09-05 北方工业大学 Method for controlling network side rectifier of brushless double-feed wind-driven generator under unbalanced electric network
CN102694394A (en) * 2012-04-28 2012-09-26 北方工业大学 Method and system for controlling current of grid-side converter of wind driven generator under unbalanced power grid condition

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105375527A (en) * 2015-12-11 2016-03-02 重庆大学 Control method and system for grid connected inverter of fault power grid
CN105375527B (en) * 2015-12-11 2018-04-03 重庆大学 The control method and system of faulty grids combining inverter
CN111525551A (en) * 2020-04-17 2020-08-11 北方民族大学 Target control method and system for rectifier under unbalanced grid voltage
CN111525551B (en) * 2020-04-17 2023-05-12 北方民族大学 Target control method and system for rectifier under unbalanced power grid voltage
CN113964877A (en) * 2021-12-21 2022-01-21 中国电力科学研究院有限公司 Method and system for improving grid-connected capacity of wind turbine generator under voltage imbalance

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