CN108964139A - A kind of hierarchical control micro-grid connection synchronizing frequency control method based on consistency algorithm - Google Patents

A kind of hierarchical control micro-grid connection synchronizing frequency control method based on consistency algorithm Download PDF

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CN108964139A
CN108964139A CN201810735218.XA CN201810735218A CN108964139A CN 108964139 A CN108964139 A CN 108964139A CN 201810735218 A CN201810735218 A CN 201810735218A CN 108964139 A CN108964139 A CN 108964139A
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李凤祥
朱鹏
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Jiangsu University
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40Synchronising a generator for connection to a network or to another generator
    • H02J3/42Synchronising a generator for connection to a network or to another generator with automatic parallel connection when synchronisation is achieved

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Abstract

本发明公开了一种基于一致性算法的分层控制微电网并网同步频率控制方法,根据考虑储能系统的荷电状态,构造了一种改进的下垂控制策略,通过对传统下垂控制策略引入考虑储能系统的荷电状态,解决了各储能单元所承担的负荷量与SOC成正比,可以有效地发挥储能的调节能力。同时,针对微电网系统的初级控制中容易出现频率偏差问题,设计了一种一致性算法实现初级控制无差调频。为了实现微电网并网频率同步,提出一种基于二级控制的微电网并网同步控制策略,可以实现微电网电压和主电网电压的同步、频率的同步,从而实现微电网由孤岛模式向并网模式的平滑切换,提高大电网及微电网系统频率稳定性及电能质量。

The invention discloses a layered control method for microgrid grid-connected synchronous frequency control based on a consensus algorithm. According to the state of charge of the energy storage system, an improved droop control strategy is constructed, and the traditional droop control strategy is introduced Considering the state of charge of the energy storage system, it is solved that the load borne by each energy storage unit is proportional to the SOC, and the adjustment ability of the energy storage can be effectively exerted. At the same time, in view of the frequency deviation problem that is prone to occur in the primary control of the microgrid system, a consensus algorithm is designed to realize the non-difference frequency modulation of the primary control. In order to achieve frequency synchronization of microgrid grid-connected, a microgrid grid-connected synchronization control strategy based on secondary control is proposed, which can realize the synchronization of microgrid voltage and main grid voltage and frequency synchronization, so as to realize the transformation of microgrid from island mode to parallel The smooth switching of the grid mode improves the frequency stability and power quality of the large grid and micro grid system.

Description

一种基于一致性算法的分层控制微电网并网同步频率控制 方法A Hierarchical Control Microgrid Grid-connected Synchronous Frequency Control Based on Consensus Algorithm method

技术领域technical field

本发明涉及微电网并网领域,具体涉及通过一致性算法的分层控制应用于微电网并网同步频率控制的方法。The invention relates to the field of grid-connected micro-grids, in particular to a method for applying the hierarchical control of the consistency algorithm to the synchronous frequency control of the grid-connected micro-grids.

背景技术Background technique

由于分布式发电具有污染少、能源利用率高、安装地点灵活等优点,并且与集中式发电相比,节省了输配电资源和运行费用,减少了集中输电的线路损耗。分布式发电可以减少电网总容量,改善电网峰谷性能,提高供电可靠性,是大电网的有力补充和有效支撑。进20年来,大部分国家已经把分布式发电提上了日程,人们开始对分布式发电系统的潜在效益展开认真研究。无疑,分布式发电是电力系统的发展趋势之一。Because distributed power generation has the advantages of less pollution, high energy utilization rate, and flexible installation location, and compared with centralized power generation, it saves power transmission and distribution resources and operating costs, and reduces the line loss of centralized power transmission. Distributed power generation can reduce the total capacity of the power grid, improve the peak and valley performance of the power grid, and improve the reliability of power supply. It is a powerful supplement and effective support for large power grids. In the past 20 years, most countries have put distributed power generation on the agenda, and people have begun to seriously study the potential benefits of distributed power generation systems. Undoubtedly, distributed generation is one of the development trends of the power system.

分布式电源尽管优点突出,但本身存在诸多问题。例如,分布式电源单机接入成本高、控制困难等。另外,分布式电源相对大电网来说是一个不可控源,因此大系统往往采取限制、隔离的方式来处置分布式电源,以期减小其对大电网的冲击。分布式电源与用户混杂而形成的有源型配网为电力系统带来了新的挑战,为解决分布式电源接入问题,协调大电网和分布式电源的矛盾,充分挖掘分布式电源为电网和用户带来的价值与效益,在本世纪初,学者们提出了微电网的概念。微电网将额定功率为几十千瓦的发电单元——微源、负荷、储能装置及控制装置等结合,形成一个单一可控的单元,同时供给电能和热能。基于微电网结构的电网调整能够方便大规模的分布式电源(DER)互联并介入中低压系统中,提供了一种充分利用DER单元的机制。Although distributed power generation has outstanding advantages, it has many problems. For example, the cost of single-machine access to distributed power is high, and control is difficult. In addition, distributed power is an uncontrollable source compared to large power grids, so large systems often use restricted and isolated methods to deal with distributed power in order to reduce their impact on large power grids. The active distribution network formed by the mixing of distributed power and users has brought new challenges to the power system. In order to solve the problem of distributed power access, coordinate the contradiction between large power grids and distributed power, and fully exploit distributed power as a power grid and the value and benefits brought by users, at the beginning of this century, scholars put forward the concept of microgrid. The microgrid combines power generation units with a rated power of tens of kilowatts—microsources, loads, energy storage devices, and control devices—to form a single controllable unit that supplies electricity and heat at the same time. The grid adjustment based on the microgrid structure can facilitate the interconnection of large-scale distributed generation (DER) and intervene in the medium and low voltage system, providing a mechanism to make full use of DER units.

在低压微电网系统中,受线路阻抗的影响,传统下垂控制难以实现有功功率和无功功率的分配,电压和频率调节就会出现一些问题。主要表现为分布式电源输出电压幅值和频率存在的差异。In a low-voltage microgrid system, due to the influence of line impedance, traditional droop control is difficult to achieve the distribution of active power and reactive power, and some problems will arise in voltage and frequency regulation. The main performance is the difference in the output voltage amplitude and frequency of the distributed power supply.

微电网中有两种运行模式:孤岛运行和并网运行。当微电网并网时即由孤岛运行切换到并网运行模式,是通过公共连接点和主电网相连的,逆变器输出的交换功率大小与微电网电压幅值和频率的测量精度密切相关。因此必须控制微电网公共连接点处电压的幅值、频率和相角,与主电网一致,否则在并网时不仅会对主电网造成很大的冲击,还会对微电网分布式电源的稳定性造成影响。There are two modes of operation in the microgrid: island operation and grid-connected operation. When the microgrid is connected to the grid, it is switched from island operation to grid-connected operation mode, which is connected to the main grid through a common connection point. The exchange power output by the inverter is closely related to the measurement accuracy of the voltage amplitude and frequency of the microgrid. Therefore, the amplitude, frequency and phase angle of the voltage at the common connection point of the microgrid must be controlled to be consistent with the main grid. Otherwise, when the grid is connected, it will not only cause a great impact on the main grid, but also affect the stability of the distributed power supply of the microgrid. sex affects.

发明内容Contents of the invention

为解决微电网并网问题,本发明提出了一种基于一致性算法的分层控制微电网并网同步频率控制方法,其主要包括两层:其中,初级控制由改进下垂控制、功率控制、电压控制以及电流控制与控制系统组成;针对微电网系统的初级控制中容易出现频率偏差问题,设计一种将一致性算法应用到初级控制中,实现初级控制中无差频率;为了实现微电网平滑并网,在二级控制中提出微电网并网同步频率控制策略,通过频率补偿使得并网瞬间两侧频率差接近为零,为微电网并网提供理论依据。In order to solve the problem of grid-connected microgrid, the present invention proposes a layered control method for synchronous frequency control of microgrid grid-connected based on consensus algorithm, which mainly includes two layers: among them, the primary control consists of improved droop control, power control, voltage control and current control and control system; in view of the frequency deviation problem that is prone to occur in the primary control of the microgrid system, a consensus algorithm is designed to apply the primary control to achieve no frequency difference in the primary control; in order to achieve smooth and parallel microgrid In the secondary control, a synchronous frequency control strategy for grid-connected microgrid is proposed. Through frequency compensation, the frequency difference on both sides of the grid is close to zero at the instant of grid-connected, providing a theoretical basis for grid-connected microgrid.

为实现上述目的,本发明所采用的技术方案是一种基于一致性算法的分层控制微电网并网同步频率控制方法,其特征在于,包括如下具体步骤:In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is a method for controlling the synchronous frequency of the grid-connected microgrid based on a consensus algorithm, which is characterized in that it includes the following specific steps:

步骤(1):检测微电网的储能荷电状态SOC与分布式电源输出的有功功率P,利用一个与P、SOC相关的符号函数得到动态有功下垂系数b;通过通信获得采用改进下垂控制的逆变器的输出电压和频率,计算相邻逆变器有功功率标幺值,结合权值的平均一致迭代算法进行有功-频率的控制;Step (1): Detect the energy storage state of charge SOC of the microgrid and the active power P output by the distributed power supply, and use a sign function related to P and SOC to obtain the dynamic active power droop coefficient b; obtain the dynamic active power droop coefficient b by using the improved droop control through communication The output voltage and frequency of the inverter, calculate the per unit value of the active power of the adjacent inverter, and combine the average consistent iterative algorithm of the weight to control the active power-frequency;

步骤(2):微电网同步并网过程中,通过Park变换将微网侧电压vodq以及主网侧电压vgdq分解得到dq轴分量vod、voq、vgd、vgq,利用PI控制器参数及vod、voq、vgd、vgq相关的函数表示同步频率fsy;微电网频率偏差Δf经同步频率fsy补偿,使得Δf小于某个规定值时,即可同步并网。Step (2): During the synchronous grid connection process of the microgrid, decompose the voltage v odq on the microgrid side and the voltage v gdq on the main grid side through Park transformation to obtain the dq axis components v od , v oq , v gd , v gq , and use PI control Synchronous frequency f sy is represented by functions related to the parameters of the generator and v od , v oq , v gd , v gq ; the frequency deviation Δf of the microgrid is compensated by the synchronous frequency f sy , so that when Δf is less than a specified value, it can be synchronously connected to the grid.

进一步,所述利用一个与P、SOC相关的符号函数得到动态有功下垂系数b的具体过程为:通过对符号函数的使用,在有功输出不足的情况下,下垂系数b与SOC成反比,各DG发电单元所承担的负荷量与SOC成正比;当有功输出富余的情况下,情况同有功输出不足;Further, the specific process of using a sign function related to P and SOC to obtain the dynamic active power droop coefficient b is: through the use of the sign function, in the case of insufficient active power output, the droop coefficient b is inversely proportional to the SOC, each DG The load borne by the power generation unit is proportional to the SOC; when the active power output is surplus, the situation is the same as the active power output is insufficient;

其中:wi为输出电压的角频率,wiref为额定电压的频率,k0为初始下垂系数,sgn(x)为符号函数,η是储能系统容量的比例系数,定义为CESS,i为储能电源i的可用容量,min[CESS,i]为储能电源i的最小容量,Pi和Piref分别是电源实际输出有功功率和额定输出有功功率。Where: w i is the angular frequency of the output voltage, w iref is the frequency of the rated voltage, k 0 is the initial droop coefficient, sgn(x) is a sign function, η is the proportional coefficient of the energy storage system capacity, defined as C ESS,i is the available capacity of energy storage power supply i, min[C ESS,i ] is the minimum capacity of energy storage power supply i, P i and P iref are the actual output active power and rated output active power of the power supply, respectively.

进一步,所述结合权值的平均一致迭代算法进行有功-频率的控制的具体过程为:随着时间的推移,系统中所有智能体的状态最终能够趋于一个相同的值,使得所有并联逆变器的有功功率标幺值收敛于其均值:Further, the specific process of active power-frequency control by the average consistent iterative algorithm combined with weights is: as time goes by, the states of all agents in the system can eventually tend to a same value, so that all parallel inverters The per unit value of the active power of the device converges to its mean value:

其中:分别为逆变器i,j的有功功率的标幺值,Wii,Wij为xi,xj在节点i上的权值。in: are the per-unit values of the active power of inverters i and j respectively, W ii and W ij are the weights of x i and x j on node i.

进一步,所述利用PI控制器参数及vod、voq、vgd、vgq相关的函数表示同步频率fsy的具体过程为:微电网可通过静态转换开关并入主电网,通过PI控制器消除频率偏差,因此微电网与主电网的同步频率可以表示为:Further, the specific process of using PI controller parameters and functions related to v od , v oq , v gd , and v gq to express the synchronous frequency f sy is as follows: the microgrid can be merged into the main grid through a static transfer switch, and the PI controller can Eliminate the frequency deviation, so the synchronous frequency of the microgrid and the main grid can be expressed as:

其中:fsy为微电网与主电网之间的同步频率,ωc为转折频率,s为拉普拉斯变换因子,kpsy和kisy分别为同步控制中PI的比例参数和积分参数。Among them: f sy is the synchronization frequency between the microgrid and the main grid, ω c is the corner frequency, s is the Laplace transform factor, k psy and k isy are the proportional parameters and integral parameters of PI in synchronous control, respectively.

进一步,所述微电网频率偏差Δf经同步频率fsy补偿:Further, the frequency deviation Δf of the microgrid is compensated by the synchronous frequency f sy :

其中:kp_Δf和ki_Δf分别为二级控制补偿器的控制参数,fMG是分布式电源端口处输出实际频率,分布式电源端口处参考频率。Among them: k p_Δf and k i_Δf are the control parameters of the secondary control compensator respectively, f MG is the actual output frequency at the distributed power supply port, Reference frequency at the distributed power port.

本发明相比现有技术具有以下优点及有益效果:本发明所提出改进下垂控制策略通过对符号函数的使用,储能余量充足的电源设置较大的下垂系数,从而使其出力相对较大,储能余量不足的电源设置较小的下垂系数,使其出力相对较小,可以有效地发挥储能的调节能力;同时,为了解决初级控制中存在的频率偏差问题,将一致性性算法应用于初级控制实现微电网无差调频。为了达到最终并网目的,在二次控制中提出微电网频率恢复达到调节两侧频率偏差,从而实现微电网并网频率同步。Compared with the prior art, the present invention has the following advantages and beneficial effects: the improved droop control strategy proposed by the present invention uses a sign function, and the power supply with sufficient energy storage margin sets a larger droop coefficient, so that its output is relatively large , the power supply with insufficient energy storage margin is set with a small droop coefficient, so that its output is relatively small, and the adjustment ability of energy storage can be effectively played; at the same time, in order to solve the problem of frequency deviation in the primary control, the consistency algorithm It is applied to the primary control to realize the frequency modulation of the microgrid without difference. In order to achieve the final purpose of grid connection, the frequency recovery of the microgrid is proposed in the secondary control to adjust the frequency deviation on both sides, so as to realize the frequency synchronization of the microgrid grid connection.

附图说明Description of drawings

图1是微电网结构图;Figure 1 is a microgrid structure diagram;

图2是改进下垂控制框图;Fig. 2 is a block diagram of improved droop control;

图3是微电网同步并网频率偏差框图;Fig. 3 is a block diagram of microgrid synchronous grid-connected frequency deviation;

图4是微电网并网的同步控制图。Figure 4 is a synchronous control diagram of microgrid grid connection.

具体实施方式Detailed ways

下面结合附图对本发明作更进一步的说明。The present invention will be further described below in conjunction with the accompanying drawings.

图1是微电网结构框图,各DG发电单元通过电力电子转换接口接入微电网,为保证微电网的出力稳定,在逆变器直流侧配备储能单元。Figure 1 is a block diagram of the microgrid structure. Each DG power generation unit is connected to the microgrid through a power electronic conversion interface. In order to ensure the stability of the output of the microgrid, an energy storage unit is equipped on the DC side of the inverter.

步骤1:初级控制由采用一致性算法的改进下垂控制、功率控制、电压控制、电流控制与控制系统组成Step 1: Primary control consists of improved droop control, power control, voltage control, current control and control system using consensus algorithm

步骤1.1,将检测到微电网的储能荷电状态SOC与分布式电源输出的有功功率P作为已知的本地信息,利用改进下垂控制方法对有功下垂系数kp进行动态整定,从而使得分布式电源根据自身的发电裕度来承担用户负荷。改进下垂控制方法是通过调节有功下垂系数的方式进行有差调节。图2是根据abc-dq变换输出的dqz轴电压分量ud、uq以及电流分量id、iq,计算出的瞬时有功功率P=ud id+uq iq,通过滤波得到平均功率LPF。Step 1.1, taking the detected energy storage state of charge SOC of the microgrid and the active power P output by the distributed power supply as known local information, and using the improved droop control method to dynamically adjust the active power droop coefficient kp, so that the distributed power supply Bear the user load according to its own power generation margin. The improved droop control method is to adjust the difference by adjusting the droop coefficient of active power. Figure 2 shows the instantaneous active power P=u d i d +u q i q calculated according to the dqz axis voltage components u d , u q and current components i d , i q output by the abc-dq transformation, and the average is obtained by filtering Power LPF.

改进下垂控制方法,具体为:Improve droop control method, specifically:

传统的频率下垂控制策略为:The traditional frequency droop control strategy is:

w=wref+k(P-Pref) (1)w=w ref +k(PP ref ) (1)

其中:w为输出电压的角频率,wref为额定电压的角频率,k为下垂系数,Pref为参考有功输出;Where: w is the angular frequency of the output voltage, w ref is the angular frequency of the rated voltage, k is the droop coefficient, P ref is the reference active output;

传统的频率下垂控制策略不考虑储能系统的SOC,其下垂系数为固定值,这就意味着当出现有功缺失或者有功过剩时,各个储能系统都是采用平均分配有功功率,这不仅没有考虑到各个储能系统SOC的差异性,而且还大大降低储能系统利用率。The traditional frequency droop control strategy does not consider the SOC of the energy storage system, and its droop coefficient is a fixed value, which means that when there is a lack of active power or an active power surplus, each energy storage system uses the average distribution of active power, which not only does not consider To the difference of SOC of each energy storage system, but also greatly reduce the utilization rate of energy storage system.

为了让储能余量充足的电源设置较大的下垂系数,从而使其有功输出相对较大,储能余量不足的电源应设置较小的下垂系数,可得改进的下垂调节关系为:In order to set a larger droop coefficient for a power supply with sufficient energy storage margin, so that its active output is relatively large, and a smaller droop coefficient should be set for a power supply with insufficient energy storage margin, the improved droop adjustment relationship can be obtained as:

其中:wi为输出电压的角频率,wiref为额定电压的角频率,k0为初始下垂系数,SOC是储能系统的荷电状态,sgn(x)为符号函数,用于返回x的正负情况,η是储能系统容量的比例系数,定义为其中,CESS,i为储能电源i的可用容量,min[CESS,i]为储能电源i的最小容量,Pi和Piref分别是电源i实际输出功率和额定输出功率。Where: w i is the angular frequency of the output voltage, wiref is the angular frequency of the rated voltage, k 0 is the initial droop coefficient, SOC is the state of charge of the energy storage system, sgn(x) is a sign function used to return x For positive and negative cases, η is the proportional coefficient of the energy storage system capacity, defined as Among them, C ESS,i is the available capacity of energy storage power source i, min[C ESS,i ] is the minimum capacity of energy storage power source i, P i and P iref are the actual output power and rated output power of power source i, respectively.

改进下垂控制,在有功过剩时,各个分布式电源给各自储能充电,使得Pi-Piref<0,即相应电源j下垂系数为:To improve the droop control, when the active power is surplus, each distributed power supply charges its own energy storage, so that P i -P iref <0, that is, the droop coefficient of the corresponding power supply j is:

储能充电功率比为:The energy storage charging power ratio is:

其中:Δw=wi-wirefWhere: Δw = w i - w iref ;

储能系统所采用的储能元件是相同产品,所以其min[CESS,i]是相同的,在计算过程可以等值消去。The energy storage elements used in the energy storage system are the same product, so their min[C ESS,i ] are the same, which can be eliminated by equivalent value in the calculation process.

因此,电源j和电源i给各自储能系统充电功率之比为:Therefore, the ratio of the charging power of power source j and power source i to their respective energy storage systems is:

采用改进的下垂控制策略后,电源有功输出增量与其储能系统的荷电状态和总容量相关。当电源j储能系统的荷电状态SOCj与电源i储能系统的荷电状态SOCi一致时,电源有功变化与储能容量成正比,从而使SOCj与SOCi按照同样的速率降低;当SOCj>SOCi时,使得SOCi增长速率会大于SOCj,此时SOCi会逐步向SOCj靠拢,在负荷扰动时间相对较长且储能容量满足要求的情况下,对于系统中采用此控制策略的多个逆变电源,其储能单元的SOC会趋于相等。After adopting the improved droop control strategy, the incremental active power output of the power supply is related to the state of charge and total capacity of the energy storage system. When the state of charge SOC j of the energy storage system of power source j is consistent with the state of charge SOC i of the energy storage system of power source i, the active power change of the power source is proportional to the energy storage capacity, so that SOC j and SOC i decrease at the same rate; When SOC j > SOC i , the growth rate of SOC i will be greater than SOC j . At this time, SOC i will gradually approach SOC j . When the load disturbance time is relatively long and the energy storage capacity meets the requirements, the system adopts With this control strategy, the SOC of the energy storage units of multiple inverter power sources tends to be equal.

类似负荷增加也是如此,故采用此改进下垂控制策略的多个分布式电源,防止对储能的过度充放电,增加储能使用寿命,其储能单元的SOC会趋于相等。The same is true for similar load increases, so multiple distributed power sources using this improved droop control strategy can prevent excessive charging and discharging of energy storage, increase the service life of energy storage, and the SOC of its energy storage units will tend to be equal.

步骤1.2,改进的下垂控制是通过调节下垂系数的方式进行有差调节。微网中的每台逆变器通过通信可以获取与其相邻的部分逆变器的信息,结合相应的分布式一致性控制算法,即可实现微电网的无差调频。In step 1.2, the improved droop control is adjusted by adjusting the droop coefficient. Each inverter in the microgrid can obtain the information of some adjacent inverters through communication, and combined with the corresponding distributed consensus control algorithm, it can realize the errorless frequency modulation of the microgrid.

一致性是指在一个多智能体系统中,随着时间的推移,系统中所有智能体的状态最终能够趋于一个相同的值,一致性算法(协议)则是指复杂系统中智能体之间相互作用的规则,一致性理论可以结合图论知识加以描述;因此提出了一种基于分布式一致性算法的无差调频控制方法。Consistency means that in a multi-agent system, as time goes by, the states of all agents in the system can eventually tend to the same value, and the consensus algorithm (protocol) refers to the relationship between agents in a complex system. The rules of interaction and consensus theory can be described in combination with graph theory knowledge; therefore, a non-difference frequency modulation control method based on distributed consensus algorithm is proposed.

其中:b为改进下垂控制中的动态下垂系数,Pi *,分别为逆变器i,j的有功功率的标幺值,Wii,Wij为xi,xj在节点i上的权值。Where: b is the dynamic droop coefficient in the improved droop control, P i * , are the per-unit values of the active power of inverters i and j respectively, W ii and W ij are the weights of x i and x j on node i.

不妨设逆变器i,j的额定容量分别为Si,Sj,则Pi *满足:It may be advisable to set the rated capacities of inverters i and j as S i and S j respectively, then P i * , Satisfy:

Pi *=Pi/Si (8)P i * =P i /S i (8)

其中Pi、Pj分别为逆变器i、j的有功功率;Among them, P i and P j are the active power of inverter i and j respectively;

由一致性算法的局部度分配权值法可知,会使得所有并联逆变器的有功功率标幺值收敛于其均值,即下式微电网稳态时成立。According to the local degree distribution weight method of the consensus algorithm, It will make the per unit value of active power of all parallel inverters converge to its mean value, that is, the following formula is established in the steady state of the microgrid.

因为仅在暂态过程中起作用,其稳态值为0,故角频率的给定值即为期望值wref,即实现了无差调频;同时,因为各逆变器的有功功率标幺值稳态时均相等,故该方法也可以保证有功功率的合理分配。because It only works in the transient process, and its steady-state value is 0, so the given value of the angular frequency is the expected value w ref , that is, the zero-difference frequency modulation is realized; at the same time, because the p.u. The state times are equal, so this method can also ensure the reasonable distribution of active power.

本发明通过一致性算法的改进下垂控制,不仅解决到储能的均衡有功输出,且实现了分布式电源有功功率的合理分配,大大提高了分布式电源的利用率及提高储能系统使用寿命,实现微电网的频率稳定性,提高电能质量。The invention not only solves the balanced active power output of the energy storage through the improved droop control of the consistency algorithm, but also realizes the reasonable distribution of the active power of the distributed power supply, greatly improves the utilization rate of the distributed power supply and improves the service life of the energy storage system. Realize the frequency stability of the microgrid and improve the power quality.

步骤2:在二级控制中实现微电网并网频率同步控制策略Step 2: Realize the frequency synchronization control strategy of the microgrid in the secondary control

步骤2.1,为了实现频率同步,必须得使微电网频率偏差减小到某个规定值(根据不同的电力系统进行确定)。图3是微电网频率偏差框图,从准同期的角度看,必须控制微电网公共连接点处电压的幅值、频率和相角,与主电网一致,否则在并网时不仅会造成很大的冲击,还会对微电网分布式电源的稳定性造成影响。In step 2.1, in order to achieve frequency synchronization, the frequency deviation of the microgrid must be reduced to a specified value (determined according to different power systems). Figure 3 is a block diagram of the frequency deviation of the microgrid. From the perspective of quasi-synchronization, the amplitude, frequency and phase angle of the voltage at the common connection point of the microgrid must be controlled to be consistent with the main grid. The shock will also affect the stability of the microgrid distributed power supply.

其中:Δf为微电网频率偏差量,kp_Δf和ki_Δf分别为二级控制的控制参数,fMG是分布式电源端口处输出实际频率,分布式电源端口处参考频率。Among them: Δf is the frequency deviation of the microgrid, k p_Δf and k i_Δf are the control parameters of the secondary control, f MG is the actual output frequency of the distributed power supply port, Reference frequency at the distributed power port.

通过频率偏差框图计算出频率偏差,为了达到并网瞬间开关两侧频率偏差接近为零,对微电网进行频率补偿,补偿值则为偏差值Δf。The frequency deviation is calculated through the frequency deviation block diagram. In order to achieve the frequency deviation on both sides of the switch at the moment of grid connection is close to zero, the frequency compensation is performed on the microgrid, and the compensation value is the deviation value Δf.

步骤2.2,为实现微电网并网频率同步控制,图4是微电网并网的同步控制图;微电网可通过静态转换开关并入主电网;此前,微电网与主电网之间不能有任何能量的交换,因此,必须通过PI控制器消除频率偏差。Step 2.2, in order to realize the synchronous control of the grid-connected frequency of the micro-grid, Figure 4 is a synchronous control diagram of the grid-connected micro-grid; the micro-grid can be merged into the main grid through a static transfer switch; before that, there cannot be any energy between the micro-grid and the main grid The exchange, therefore, must be eliminated by the PI controller frequency deviation.

根据abc-dq坐标变换下输出的微网侧电压vodq以及主网侧电压vgdq,并将vodq、vgdq分解得到dq轴分量vod、voq、vgd、vgq;当微网电压与主网电压一致时(voabc=vgabc)时,vgqvod-vgdvoq=0,这样达到消除电压偏差的目的。According to the microgrid side voltage v odq and the main grid side voltage v gdq output under the abc-dq coordinate transformation, decompose v odq and v gdq to obtain the dq axis components v od , v oq , v gd , v gq ; when the microgrid When the voltage is consistent with the main grid voltage (v oabc =v gabc ), v gq v od -v gd v oq =0, so as to eliminate the voltage deviation.

微电网与主电网的同步频率可以表示为:The synchronous frequency between the microgrid and the main grid can be expressed as:

其中:fsy为微电网与主电网之间的同步频率,ωc为转折频率,s为拉普拉斯变换因子,vod、voq分别为vodq的d轴和q轴分量,vgd、vgq分别为vgdq的d轴和q轴分量,kpsy和kisy分别为同步控制中PI的比例参数和积分参数。Where: f sy is the synchronous frequency between the microgrid and the main grid, ω c is the corner frequency, s is the Laplace transform factor, v od and v oq are the d-axis and q-axis components of v odq respectively, v gd , v gq are the d-axis and q-axis components of v gdq respectively, and k psy and k isy are the proportional parameters and integral parameters of PI in synchronous control, respectively.

为了使同步频率fsy补偿达到调节频率偏差参数的目的,在微电网同步并网过程中,频率偏差表达式:In order to make the compensation of synchronous frequency f sy achieve the purpose of adjusting frequency deviation parameters, in the process of microgrid synchronous grid connection, the expression of frequency deviation is:

综上可知,在同步并网的过程中,首先根据初级控制实现频率恢复,当微电网的频率偏差即Δf小于某个值后,即可利用公式(13)实现频率的同步,实现微电网由孤岛模式向并网模式的平滑切换。In summary, in the process of synchronous grid-connection, the frequency recovery is firstly realized according to the primary control. When the frequency deviation of the microgrid, that is, Δf, is less than a certain value, the frequency synchronization can be realized by using the formula (13), and the microgrid is realized by Smooth switching from island mode to grid-connected mode.

以上实施例仅用于说明本发明的设计思想和特点,其目的在于使本领域内的技术人员能够了解本发明的内容并据以实施,本发明的保护范围不限于上述实施例。所以,凡依据本发明所揭示的原理、设计思路所作的等同变化或修饰,均在本发明的保护范围之内。The above embodiments are only used to illustrate the design concept and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims (5)

1. a kind of hierarchical control micro-grid connection synchronizing frequency control method based on consistency algorithm, which is characterized in that including Following specific steps:
Step (1): detect micro-capacitance sensor energy storage charge state SOC and distributed generation resource output active-power P, using one with P, the relevant sign function of SOC obtains the active sagging coefficient b of dynamic;It is obtained by communication using the inverter for improving sagging control Output voltage and frequency, calculate adjacent inverter active power per unit value, in conjunction with weight average homogeneity iterative algorithm carry out The control of active-frequency;
Step (2): micro-capacitance sensor synchronize it is grid-connected during, by Park transformation by micro- voltage on line side vodqAnd main voltage on line side vgdq Decomposition obtains dq axis component vod、voq、vgd、vgq, utilize PI controller parameter and vod、voq、vgd、vgqRelevant function representation is same Synchronizing frequency fsy;The synchronized frequency f of micro-capacitance sensor frequency deviation Δ fsyCompensation can synchronize when so that Δ f being less than some specified value It is grid-connected.
2. a kind of hierarchical control micro-grid connection synchronizing frequency controlling party based on consistency algorithm according to claim 1 Method, which is characterized in that described to obtain the specific mistake of the active sagging coefficient b of dynamic using a sign function relevant to P, SOC Journey are as follows: by the use to sign function, in the active insufficient situation of output, sagging coefficient b and SOC is inversely proportional, each DG hair The load that electric unit is undertaken is directly proportional to SOC;In the case that active output is more than needed, situation is insufficient with active output;
Wherein: wiFor the angular frequency of output voltage, wirefFor the frequency of voltage rating, k0For initial sagging coefficient, sgn (x) is symbol Number function, η is the proportionality coefficient of energy storage system capacity, is defined asCESS,iFor the available appearance of accumulation power supply i Amount, min [CESS,i] be accumulation power supply i minimum capacity, PiAnd PirefIt is power supply reality output active power respectively and specified defeated Active power out.
3. a kind of hierarchical control micro-grid connection synchronizing frequency control based on consistency algorithm according to claim 1 or 2 Method processed, which is characterized in that the average homogeneity iterative algorithm of the combination weight carries out the detailed process of the control of active-frequency Are as follows: over time, the state of all intelligent bodies can finally tend to an identical value in system, so that all parallel connections The active power per unit value of inverter converges on its mean value:
Wherein: Pi *,The per unit value of the active power of respectively inverter i, j, Wii,WijFor xi,xjWeight in node i.
4. a kind of hierarchical control micro-grid connection synchronizing frequency controlling party based on consistency algorithm according to claim 1 Method, which is characterized in that described to utilize PI controller parameter and vod、voq、vgd、vgqRelevant function representation synchronizing frequency fsyTool Body process are as follows: micro-capacitance sensor can pass through static transfer switch and become owner of power grid, eliminate frequency departure, therefore micro- electricity by PI controller The synchronizing frequency of net and main power grid can indicate are as follows:
Wherein: fsyFor the synchronizing frequency between micro-capacitance sensor and main power grid, ωcFor corner frequency, s is the Laplace transform factor, kpsyAnd kisyThe scale parameter and integral parameter of PI respectively in synchronously control.
5. a kind of hierarchical control micro-grid connection synchronizing frequency controlling party based on consistency algorithm according to claim 1 Method, which is characterized in that the synchronized frequency f of micro-capacitance sensor frequency deviation Δ fsyCompensation:
Wherein: kp_ΔfAnd ki_ΔfThe respectively control parameter of Two-stage control compensator, fMGIt is to be exported in fact at distributed electrical source port Border frequency,Reference frequency at distributed electrical source port.
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Application publication date: 20181207