Individual Phase Control of a Static Compensator for Load Compensation and Voltage Balancing and Regulation

The purpose of this paper is to discuss the developments in control strategies for static compensators using programmable high speed digital controllers. Individual phase control of static compensators has been used in the past for balancing and power factor correction of arc furnace and single phase railway loads. With the advancements in programmable high speed controllers based on microprocessor technology, more complex computations can be accurately performed for the additional purpose of regulating and balancing the voltage feeding such loads. Other developments that will be discussed are the use of symmetrical firing angle control to eliminate the even harmonics in the current spectrum and hence, reduce the cost of filtering, and the synchronization of the controller to the phase-locked-loop firing circuit to compensate for frequency variations. The results of simulator studies will be presented.     

Microprocessor-implemented digital filters for inrush current detection

A digital inrush-current detection algorithm is described, which is based on a least-squares curve fitting of the sampled differential current by a decaying DC and five harmonic components. The digital filters developed on the basis of this theory are implemented by means of a microprocessor. Laboratory tests demonstrate that the microprocessor is capable of handling the rather complicated digital filtering. To carry out these tests, the digital filters are incorporated in a protection scheme. The resulting digital protection is tested online. Some typical programming features, necessary for microprocessor implementation, are discussed.     

Microcomputer based digital differential relaying for generator protection: Real time test results

The paper presents the development of a digital differential relaying scheme around a 16-bit microprocessor for generator winding protection. It uses a simple filter algorithm which is based on cross-correlation with a heptagonal wave for the extraction of fundamental frequency components of differential and sum currents. Application of this filter and use of the real parts alone, instead of both the real and imaginary parts, of the fundamental frequency components for the relaying reduces the computation requirement drastically, thus enabling implementation of a complete three-phase differential relay on a single microprocessor without requiring a coprocessor or multiplier. The relay has been tested in real time on simulated generator currents representing internal-, external- and no-fault conditions separately. The test results agree well with the results of off-line evaluation reported earlier and point to a successful implementation of the differential relaying algorithm on a microprocessor in real time.     

Advances in Digital Control for High-frequency Switched-mode Power Converters

Over the last decade, practical digital control of high-frequency switched-mode power converters has moved from proof-of-concept demonstrations to controller chips commercially available from multiple vendors ,with applica-tions to point-of-load and isolated DC/DC converters, microprocessor power supplies,power-factor-correction rectifiers, and others.This paper summarizes some of the advances in the area, including approaches to realizations of high-per-formance, high-frequency digital pulse-width modulated ( DPWM ) controllers, related analysis, modeling and design techniques, as well as performance gains enabled by digital control such as dynamic response and efficiency improve-ments.Examples of experimentally demonstrated results are presented, together with pointers to areas of current and future research and development.     

实用微机保护装置可靠性分析与研究

用户需求的提高及电力系统的发展要求微机保护装置具备更高的可靠性。阐述了保护主要环节可靠性设计的主要依据及原则，并举例说明了其中典型部分（如电源部分、数字信号线等）的可靠性设计和措施。在此基础上，还提出了保护可靠性研究中尚待解决的问题，这些问题的解决不但可以有效地提高保护装置本身的可靠性，而且还将有助于保护具备顺应电力系统发展趋势，提高其对系统变化的适应能力。     

A Microprocessor-Based Controller for a Three-Phase Controlled Rectifier Bridge

A complete design of a microprocessor-based control circuit for a three-phase controlled rectifier bridge is presented. The Motorola M6802 microprocessor is used, and a flowchart and program listing are provided. Practical problems such as synchronization with noisy references are discussed, and modifications to the basic program are indicated. The basic control' philosophy developed can be extended to. the entire class of phase controlled systems, e.g., cyclo- converters, ac-voltge controllers, etc.     

A Bit-Sliced Computer Design Laboratnry

A laboratory course in computer organization and design based on the use of bit-sliced microprocessor parts is described. Course objectives are given and the course content is presented. The special laboratory facility developed for the course, which is a microcomputer-based system, is described. Experience in operating the course over the first year is discussed, and plans for the future are outlined.     

Purdue's Junior-Level Control Laboratory with Microprocessors

A microprocessor-based direct digital control system laboratory developed at Purdue University is discussed. The microprocessor controller interfaces directly to an analog computer for simulation control or to control components such as motors, heaters, etc. Available resident processor routines (A/D, D/A, arithmetic, timing, etc.) can be easily configured into a digital control system program allowing strategies to be quickly developed and tested. Al operations are performed directly at the control station via a terminal keyboard, and the system has the potential for stand-alone operation with a graphics output terminal A typical digital control system example-servo position control-has been developed for use in the Junior Control Laboratory. In addition to unlimited possibilities for software strategies, patchable features such as comparators, logic circuitry, timing functions, etc., are available on the front panel, allowing quick, efficient development of a complete digital control system.     

基于离散时间趋近率控制与内模控制的永磁同步电动机传动系统

提出一种永磁同步电动机（PMSM)鲁棒控制技术，以削弱系统性能对电机模型精度的敏感性，简化控制器设计过程。首先在电流控制中应用对模型误差高度鲁棒的内模控制(IMC)，得到同步坐标系下直接由电机参数和期望闭环带宽表示的PI型IMC控制器，改善电流环特性的同时避免了调节PI参数。随后提出了基于离散时间趋近率控制(RLC)的PMSM速度控制器，其离散解满足了数字控制对离散系统分析与设计的需要，分析了速度环中RLC控制器的稳定性。仿真结果验证了所提传动系统的优良性能。     

An adaptive stabilizer for thyristor controlled static VARcompensators for power systems

The authors present the analytical development of a controller scheme for a static VAr system and present detailed simulation results to highlight its effectiveness in comparison with a discrete PI (proportional-integral) stabilizer under a variety of operating conditions for power transmission systems. The adaptive stabilizer is suitable for microprocessor digital implementation as the numerical steps involved are minimal. The adaptive stabilizer uses a stochastic variant simplified parameter estimator routine, thus providing a faster sampling rate and identification of a larger number of parameters in real time. The implementation of this stabilizer is simple as it involves additions, multiplications without matrix inversion, etc     

Features of modes of a multizone integrating controller with an even number of relay elements

Operation modes of an integrating multizone controller with pulse-width modulation frequency and an even number of relay elements are discussed. Integrating multizone controllers have high noise protection, precision, multifunctionality, and simple technical realization. Due to such properties, they make it possible to solve an entire complex of technical problems to improve the resource and energy-efficiency characteristics of systems of technological process control based on these controllers. A block scheme of a multizone regulator with an even number of relay elements is given. Time diagrams of a multizone controller with two and four relay elements are shown so as to explain the principles of its operation. Based on this analysis, recommendations are given for the use of a multizone controller in low-voltage information devices, in particular, in regulators, sensors, etc. The field of application of integrating multizone controllers in control systems of electric drives in technological devices is determined. In particular, an example of construction of a discrete control system of a group of electric drives with parallel control channels is discussed. The block scheme of a discrete control system of the group with an odd number of asynchronous electric water-pump drives controlled by thyristor regulators is presented. Such a solution provides soft-start electric drives with a predetermined limiter of starting current. In the proposed scheme, the main disadvantage of a multizone system with an even number of relay elements is eliminated. In particular, blocking of additional relay element commutation is implemented when the multizone controller switches from one modulation zone to another.     

DSP数字交流调速系统的硬件设计

交流电机调速系统正向数字化方向发展，一般的微控制器缺乏进行复杂计算（如矢量运算）的能力，而32位微处理器相对又较昂贵，32位数字信号处理器DSP由于其运算速度快，性能价格比高，效能超出其他计算机机处理器10－50倍，这使得交流调速系统的性能和精度更优于传统的交流调速系统。论文讨论了高速DSP在交流调速系统中的外部硬件设计。     

An analysis of correspondence between real and theoretical characteristics of microprocessor PID controllers

The experimental characteristics of virtual PID controllers implemented in R-380 microprocessor controllers used in the Kvint computerized automation suite are presented, along with the results from an analysis of their correspondence to theoretical algorithms.     

基于比例谐振调节器的逆变器双环控制策略研究

逆变器采用比例谐振(PR)调节理论上能够实现无静差的输出电压。分析比较了数字实现的谐振控制器在两种离散方式下的特性,选择了脉冲不变法作为谐振控制器的离散方法。以单相全桥逆变器为研究对象,在离散域上详细设计了采用PR调节的双环数字控制策略;加入多个谐波谐振控制器减小非线性负载对输出电压的影响。分析比较了PR调节和PI调节两种策略下的输出外特性。理论分析和实验结果表明,采用该方案的逆变器具有优良的输出特性。     

A Performance Analysis of Microprocessor-Based Control Systems Applied to Adjustable Speed Motor Drives

Speed regulators for motor drives can be classified into four types according to the degree of accuracy and the response time required for a given application. Formulas are presented which can be used to determine the number of bits and the sampling time which are required of a microprocessor for a thyristor drive microprocessor-based speed regulating system. A systematic approach is also proposed which application engineers can use to evaluate and select the most adequate microprocessor from those commercially available for different types of digital speed regulators.     

A Microprocessor System for the Discrete-Time Control Laboratory

The topics studied in discrete-time signal processing and control are particularly abstract and some aid to learning these concepts is needed. One possible type of aid is discussed which employs state-of-the-art hardware to implement a programmable digital filter which may be useful in discussing sampling, digital filtering or may be inserted as a discrete-time compensator into a continuous-time control loop. The device employs modern microprocessor hardware including ROM, RAM, interval timer, digital-to-analog, and analog-to-digital converters. Digital filters up to fourth order may be programmed as may the sampling interval to be employed. Several applications to the control of a typical continuous-time plant are given.     

Tuning methods for typical predictive control algorithms

For predictive control algorithms based on typical linear controllers, exact and approximate methods for calculating optimal tunings are put forward. Optimally-tuned predictive algorithms are shown as being capable of markedly increasing the control quality and simultaneously of more fully implementing capabilities of microprocessor devices.     

一种低压数字继电器的设计

基于微处理器DS80C390和电能表芯片CS5460设计了一种低压数字继电器,既能够对低压系统进行保护,又能对各种电量进行计量,同时具有遥控、遥测、遥信功能。给出了硬件及软件设计方案,并对几项关键技术作了详尽的分析。实验结果表明,所设计继电器不仅实时性好、电磁兼容性强,而且体积小、成本低、容易实现。     

数字电流纵差保护中数据采样的两种同步方法

在利用微处理器和数据通信技术实现数字式电流纵差保护时 ,线路两端电流的同步采样是必需解决的关键技术问题。本文对现场设备 (LFP -931A型光纤电流差动保护 )中采用的同步采样方法和基于GPS的同步采样方法的基本原理进行了详细描述 ,对两种方法进行了分析和比较 ,并对现场中运行设备的数据同步采样系统提出了一种技术改进方案设想。