工业的跳跃式进步，使得煤炭、石油等不可再生能源被过度开采，不仅在使用过程中造成了对环境的污染，而且这些化石矿物分布的不均，也使世界各国为此频起争端。面对这样的窘境，开发清洁的、可再生能源代替，对解决这些问题有着重要的意义。而风能就是一种新型的、无污染能源，利用风能发电已经被全世界广泛提倡和推广。随着相关科学技术的不断进步，变桨风电机组这种通过调节桨距角保持机组输出功率稳定的发电方式逐渐成为了大型风电机组的主流，其相关的变桨控制技术也在不断地完善、进步。 通过阅读大量国内外文献资料，研究风力发电机组及控制系统的基本结构和工作原理，对变桨控制系统的原理、结构、功能和工作流程进行了详细的分析，结合实际生产工艺要求，对市场上的主流变桨驱动装置进行了比较和选型，最终采用三桨叶独立电动变桨方式。 由于PLC在工业控制领域应用广泛，拥有很多优势，且价格合理，综合各方面因素，本文选择西门子S7-300作为控制器。 调节桨距角以保持机组输出功率最优是本文研究和设计控制系统的主要内容。通过分析风电机组的空气动力学特性，在此基础上设计了变桨控制系统在不同风速段时的控制策略，鉴于PID控制稳定性好、控制算法简单、响应速度快且能实现无差调节等特点，本文利用西门子STEP 7下位软件，通过功率偏差及PID算法调节等相关程序块进行了控制程序编写。利用力控组态软件良好的兼容性，在上位机创建了变桨控制系统的操作监控画面，并完成了与下位机的通讯组态。 通过调试，本文所设计的变桨控制系统能够在各种风速条件下，通过自动调节桨距角的大小，始终维持机组输出功率稳定。软、硬件都能够满足机组的控制要求，运行良好。调试过程中对DTU装置的尝试，也成功的摆脱了电缆的束缚，即使监控上位机远在异地，也可实时的监控机组运行。

As a result of highly developed industry-coal, oil and other non-renewable energy are overexploited, which not only pollutes the environment, but also causes frequent conflicts in worldwide because of uneven distribution of these fossils. Based on this issue how to find and explore other renewable energy to be back up resource is quite significant. Wind is a new, non-polluting energy sources, the use of wind power has been widely advocated and promoted worldwide. With the continuous progress of science and technology, wind turbine pitch control system which maintains a stable output power by adjusting the pitch angle has gradually become the mainstream way of large scale wind turbine; with its related pitch control technology is constantly improved. In this article the basic structure and operating principle of the wind turbine and control system is introduced. It focus on an important part of current mainstream wind turbine - the principle, structure, functions and workflows of pitch control system and provides a detailed analysis of the production process, and in accordance with the requirements designs the hardware structure of the pitch control system, and PLC-based control system architecture. This paper analyzed every section of the pitch control system, and lists the main parameters of the selection, and configure the system’s hardware by using Siemens S7-300 series PLC control system. Main content of the paper is on how to adjust the pitch angle to maintain optimal output power unit as well as on design of control systems. To fulfill requirements for plant operation under different wind conditions, we use the Siemens STEP 7 lower position machine software, per power deviation and PID algorithm adjustments and other relevant program modules to realize edition of ladder diagram. By force control software, this created in the PC monitor screen operation of pitch control system for the operation and maintenance personnel to provide a good human-computer interaction interface. By testing, all pitch control system designed hardware and software in the article are able to meet requirements of the control unit and run smoothly. The test of DTU device in the process also successfully got rid of the shackles of cable, even if the pc monitors located remotely, real-time monitoring of plant operation may get to.