含分布式电源的直流配电网协调控制研究

发布时间：2018-03-24 11:35

本文选题：直流配电网　切入点：分布式电源　出处：《华北电力大学(北京)》2017年博士论文

【摘要】：随着分布式电源在配电网中渗透率的增加,其稳定性和可靠性问题变得尤为复杂。直流配电网兼具灵活性与高效性的优点,且不存在无功环流及功角稳定等问题,是分布式电源更为理想的组网方式。由于直流配电网中没有无功和频率问题,其功率-电压控制是稳定及优化运行的核心技术。对于端数较多的直流配电网可采用一次调压与二次调压相结合进行电网功率调节,把复杂电网的稳定运行与优化运行在不同的时间尺度上进行解耦控制。此外,在直流配电网中,各分布式电源通过电力电子变流器并网,对直流系统的惯性几乎没有贡献,这将成为分布式能源大规模接入配电网之后面临的新问题。随着能源结构多样化及用户需求的精益化,对直流配电系统供电质量及运行特性的要求也在不断提高。本文主要研究含分布式电源的直流配电网协调控制方法,以提高其暂态运行稳定性,改善系统运行效率及供电质量。主要工作及成果如下:1.建立了包含风力发电的直流配电网各单元数学模型,包括永磁风电机组、蓄电池储能单元、联网变流器以及交直流负荷的数学模型。研究了直流配电网中各单元的传统控制策略及系统运行特性,为各单元惯性控制策略的提出,及预测控制模型的建立奠定了基础。2.提出了直流配电网一次与二次电压控制相结合的调压体系。在电压分段一次调压方法的基础上,深入研究系统各单元控制响应特性,提出了直流配电网自适应惯性调节方法,以解决直流配电网低惯性问题。对于风力发电单元通过控制旋转动能的吸收或释放来改善功率输出特性,对于储能及并网单元也可以通过改变相应的控制参数,虚拟出与直流电压变化相适应的惯性响应,增强了直流配电网的抗扰能力及暂态运行稳定性。3.提出了一种基于变流器模型的本地预测控制方法,以配合系统惯性调节时对变流器响应快速性的要求。该方法中,在对各单元变流器数学模型进行分析推导的基础上,分别建立了机侧变流器,网侧变流器及储能变流器预测控制模型。为消除数字执行过程的单步延时,引入了两步预测误差函数从而形成了多目标优化。采用分类排序法选择目标向量,解决了传统基于PI的双闭环控制参数整定繁琐的问题。将基于变流器模型的预测控制方法与惯性调节相结合,提高了系统控制响应速度,增强了直流配电网暂态运行稳定性。4.设计了基于模型预测控制器的风电直流配电网集散控制系统。为满足系统经济运行及高质量电能的要求,采用模型预测控制器作为其集散控制体系架构中的主控制单元,以产生本地控制器优化参考信号。本地控制器根据系统运行状态特性,在优化参考值的基础上对系统运行状态进行细调。同时采用冗余参考信号,通信故障时采用基于直流电压的系统功率分配方案,以规避该分层控制结构中通信故障对系统稳定性的影响,如此,既能够保证正常运行时,系统高效运行及对电能质量的要求,又能在故障时保证系统不失稳。
[Abstract]:With the increase of distributed generation in distribution network penetration, its stability and reliability problems become more complex. The DC power distribution network has advantages of both flexibility and efficiency, and does not exist without the problems of power circulation and power angle stability, power is distributed more ideal network. Because of the lack of reactive power and frequency of the DC power distribution in the net, the power voltage control is the core technology of stable and optimal operation. Using a voltage and the two voltage combined power adjustable DC power distribution network for a large number of end, the complex grid stable operation and optimal operation of decoupling control in different time scales in addition. And in the DC distribution network, the distributed power grid through power electronic converters of DC, the inertia of the system is almost no contribution, it will be faced after the large-scale distributed energy distribution network access The new problem. With the energy structure diversification and user needs to lean, DC distribution system and operation characteristics of the power quality requirements are constantly improved. Coordinated control method of DC power distribution network is mainly studied in this paper with distributed power, in order to improve the transient stability, improve system efficiency and power quality. The main work and achievements are as follows: 1. the DC distribution network of each unit mathematical model including wind power, including the permanent magnet wind generator, battery energy storage unit, the mathematical model of AC / DC converter and network load. On the operating characteristics of the traditional control strategy and system of each unit of DC distribution network, for each unit inertia control strategy the prediction model, and laid the foundation for.2. proposed a DC distribution network and the two voltage control combined pressure regulating system. In section one voltage Based on the voltage regulating method, in-depth study of the system of each unit control response characteristics, put forward the adaptive inertia DC distribution network adjustment method to solve the DC distribution network low inertia problem. For wind power generation unit by controlling the rotational kinetic energy absorption or release to improve the power output characteristics for energy storage and grid unit can shift the corresponding control parameters, virtual and DC voltage changes to adapt to the inertial response, enhance the anti disturbance capability and transient stability of the.3. DC power distribution network presents a predictive control method based on local model of converter, to match the system inertia quick response requirements for converter during adjustment. In this method, the for each unit converter mathematical model is derived on the basis of machine side converter are established respectively, and the grid side converter converter model for predictive control. Eliminate one step delay of digital implementation process, the introduction of the two step prediction error function to form a multi-objective optimization. Select the target vector by sorting method, to solve the traditional double closed loop PI control parameter tuning based on complicated problems. The prediction model of converter control system and inertial modulation method based on improved system the control response speed, enhance the transient stability of the.4. DC power distribution network design model predictive controller of wind power DC power distribution network based on the distributed control system. In order to satisfy the system requirements of high quality and economic operation of electric energy, a model predictive controller as the main control unit of distributed control system architecture, to optimize the local controller reference signal the local controller. According to the characteristics of the running state of the system, for fine-tuning the operation state of the system on the foundation of the optimum reference value. At the same time using redundancy More than the reference signal, the system power allocation scheme based on DC voltage communication fault, to avoid the influence of hierarchical control structure in communication fault on the stability of the system, which can ensure the normal operation, efficient operation of the system and the requirements of power quality, but also in the failure to prevent system instability.

【学位授予单位】：华北电力大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM721.1

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