基于储能电池的双模式逆变器的研究

发布时间：2018-05-05 10:40

本文选题：电池储能 + 双模式逆变器　；参考：《华北电力大学》2014年硕士论文

【摘要】：随着大规模分布式电源的广泛应用以及电网调峰调频需求的增长,储能装置正逐步成为电网中的重要设备,它能够起到削峰填谷、平抑分布式电源输出功率的波动、充当应急电源的作用。蓄电池是储能装置的一个重要分类,目前广泛应用的二次电池包括铅酸蓄电池和锂电池。电力电子变流器是储能电池接入电网或微电网的接口,主要拓扑包括双向升降压斩波电路、单相全桥逆变电路、三相半桥逆变电路。用于储能电池的逆变器,要求能够并网运行,也可以在电网故障时离网运行,因此称作双模式逆变器。本文以此为研究对象,开展了以下研究工作。本文首先在不同坐标系下建立了用于储能电池的双模式逆变器的数学模型(包括并网运行和离网运行)；分析了SVPWM的原理及实现方法。然后根据实际工程项目对储能逆变器的功能要求,设计了基于电池荷电状态(Soc)、电网状态、分布式电源输出情况这三个约束条件下储能逆变器的多种工作模式及其选择流程。论文重点研究了储能逆变器各个运行模式的控制策略,以及保证平滑切换的控制方法,并针对各种工况可能遇到的问题,提出或设计了最为适合的控制策略：(1)并网模式下,采取双闭环控制策略。平抑分布式电源波动时,控制外环以调度中心下发的指定功率为参考值,实际输出功率为指定值,内环为电感电流环；(2)对储能电池充电时,根据电池管理系统下发可对电池执行的操作以及电池端电压,选择相应的充电方式如恒压充电、恒流充电、涓流充电等；恒压充电时,外环输出应该取负作为内环的给定值；(3)选择外环限幅值为额定功率下的电流幅值,以避免并网时实际运行模式切换导致储能逆变器出现过流情况；(4)离网运行时,采取单环控制,控制目标为本地负载端电压；(5)提出采取电网电压正负序分量作为标准判断电网状态的方法,用于在电网故障或者从故障中恢复时发生的并网／离网切换,相比于主动式孤岛检测,能够弥补无法判断电网故障恢复的缺陷；(6)提出从并网切换至离网运行的方法是,并网运行时记录电网电压幅值相位,判断出电网发生故障后,以正常时的幅值相位按照50Hz的频率构造参考电压,保证负载端电压不发生突变；(7)提出从离网切换至并网运行的方法是,电网从故障中恢复后,以电网相位对负载端电压相位进行坐标变换,求出相位差和幅值差,调整逆变器输出电压直到相位差和幅值差为零,然后闭合并网开关。论文在进行系统地理论分析的基础上,在PSCAD/EMTDC仿真平台中搭建了完整的储能系统(含双模式逆变器)模型,对上述各种控制策略进行了验证。结合实际工程项目,研发了一台30kVA的储能逆变器样机,并进行了相关控制策略的检验,取得了良好的结果。
[Abstract]:With the wide application of large-scale distributed generation and the increasing demand for peak shaving and frequency modulation in power grid, energy storage device is gradually becoming an important equipment in the power network, which can cut the peak and fill the valley, and stabilize the fluctuation of the output power of the distributed power supply. Act as an emergency power source. Battery is an important classification of energy storage devices. At present, secondary batteries are widely used, including lead-acid batteries and lithium batteries. Power electronic converter is the interface of energy storage battery to power grid or microgrid. The main topologies include bi-directional lifting chopper circuit, single-phase full-bridge inverter circuit, three-phase half-bridge inverter circuit. The inverter used for energy storage battery needs to be connected to the grid and can be operated off the grid in the event of power network failure, so it is called a dual-mode inverter. In this paper, as the research object, the following research work has been carried out. In this paper, the mathematical model of dual-mode inverter for energy storage battery is established in different coordinate systems (including grid-connected operation and off-grid operation), and the principle and implementation method of SVPWM are analyzed. Then according to the functional requirements of the energy storage inverter in the actual project, the working modes and the selection flow of the energy storage inverter are designed under the three constraints of battery charged state, power grid state and distributed power output. This paper focuses on the control strategy of each operation mode of the energy storage inverter and the control method to ensure smooth switching. Aiming at the problems that may be encountered in various operating conditions, the most suitable control strategy: 1) grid-connected mode is proposed or designed. Double closed loop control strategy is adopted. When suppressing the fluctuation of distributed power supply, the control outer loop takes the specified power generated by the dispatching center as the reference value, the actual output power as the specified value, and the inner loop as the inductance current ring / 2) to charge the energy storage cell. According to the operation of battery management system and battery terminal voltage, select the corresponding charging methods such as constant voltage charge, constant current charge, trickle charge, etc. The output of outer loop should be negative as the given value of inner loop / 3) the outer loop limit should be selected as the current amplitude under rated power, so as to avoid overcurrent of the energy storage inverter caused by the switching of actual operation mode during grid-connected operation, the single loop control should be adopted when operating off the grid. The control target is local load terminal voltage. (5) A method is proposed to use the positive and negative sequence components of the grid voltage as the standard to judge the state of the power network, which can be used for grid-connected / off-grid switching in the event of a fault or recovery from the fault. Compared with active islanding detection, the method of switching from grid-connected to off-grid operation is put forward, which can make up for the defect that can not judge the fault recovery of power network. The method is to record the amplitude and phase of the voltage when the grid is connected, and to judge the fault of the power network. Using the normal amplitude and phase to construct the reference voltage according to the frequency of 50Hz to ensure that the voltage of the load terminal does not have a sudden change, the method of switching from off-grid to grid-connected operation is put forward, that is, after the power network is recovered from the fault, The phase difference and amplitude difference are calculated by coordinate transformation of load terminal voltage phase based on power network phase, and the output voltage of inverter is adjusted until the phase difference and amplitude difference are zero, and then the grid-connected switch is closed. On the basis of systematic theoretical analysis, a complete model of energy storage system (including dual-mode inverter) is built on the PSCAD/EMTDC simulation platform, and the control strategies mentioned above are verified. A prototype of 30kVA energy storage inverter is developed, and the relevant control strategies are tested, and good results are obtained.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

【参考文献】