Research and development of excitation system of s

2022-08-24
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3. Data processing software package

development and research of synchronous generator excitation system based on DSP

Abstract: excitation system is an important part of synchronous generator, which directly affects the operating characteristics of generator and power system. This paper introduces the development and research of a new type of synchronous generator digital excitation regulator based on TMS320LF2407 microcontroller and dual channel structure

key words: synchronous generator, excitation, microcontroller, DSP, PID

0 development of excitation regulator

from the evolution of components and structures of excitation regulator device, it has experienced several stages from electromechanical type to electromagnetic type to semi conductive type. In the past, most excitation devices were composed of analog components. Because analog components were easily affected by temperature, the setting value drifted with the change of season, the linearity of analog feedback signal was poor, the analog given signal was inaccurate, and the repeatability was poor, which made the whole system unstable, the loss of system hardware resources was large, and it was difficult to change analog components, exchange information with the superior control system, debugging was inconvenient, and fault diagnosis was not easy

with the development of computer technology, the transformation from control information processing to digital processing has been accelerated. Many companies and enterprises at home and abroad have begun to study microcomputer digital excitation devices with microcomputer as the core. The deep digital technology is adopted to integrate the excitation device in hardware, which can easily realize the modern control requirements, enhance the anti-interference ability, and is suitable for working in a harsh field environment. In industrial control, single-chip microcomputer and industrial computer are mostly used to form excitation regulator, which has achieved good results

1 overview of tms320x240x series DSP

tms320x240x is a TMS320 series DSP product, which is suitable for many digital motor control (DMC) and other embedded control applications. This series of products is based on c2xlp 16 bit, fixed-point, low-power DSP, with screw drive and rack drive CPU, and integrates a series of on-chip peripherals, on-chip ROM, flash program memory and on-chip bidirectional RAM (daram). That is, a high-performance DSP core and on-chip and off-chip 6 The friction force of the force measuring piston in the oil cylinder increases or gets stuck. The device is integrated into a chip. Tms320x240x series has become a cheap substitute for the traditional micro control unit (MCUs) and expensive multi chip design. With the processing speed of 30million instructions per second, tms320x240x DSP controller can provide far more performance than traditional 16 bit microcontrollers and microprocessors

the instruction execution speed of TMS320LF2407 is 30mips, and almost all instructions can be executed in a single cycle of 33ns. This makes the real-time implementation of high-performance complex control algorithms possible. It has the architecture characteristics necessary for high-speed signal processing and digital control functions, has powerful on-chip i/o ports, and it has the peripheral equipment necessary to provide a single-chip solution for motor control applications. This application optimized peripheral unit, together with the high-performance DSP core, makes it possible to use advanced control technology in the high-precision, efficient and full speed control of all types of motors

the following are the performance characteristics of TMS320LF2407:

· TMS320C2xx core CPU

□ 32-bit central arithmetic logic unit (calu), 32-bit adder

□ 16 bit parallel multiplier, 32-bit product, 3 scaling shift registers

□ 8 16 bit auxiliary registers, with a special arithmetic unit, Indirect addressing for data memory

· memory

□ 544 word x16 bit double ended data/program daram

□ 2K word x16 bit single port saram

□ 32K x16 bit on-chip flash program memory

□ 256 word x16 bit on-chip boot ROM

□ 224k word x16 bit maximum addressing memory space (64K word program space, 64K word data space, 64K word i/o space, 32K word global space of K word)

□ external memory interface module with software wait state generator, With 16 bit address bus and 16 bit data bus

· event management modules a and B

□ four 16 bit general timers

□ comparison/pulse width modulation (PWM) channel 10/16

□ capture channel/quadrature encoder pulse interface 6/4

· power supply

□ static CMOS technology

□ power supply voltage 3.3v

· watchdog timer

· can interface: with controller local area network (CAN2.0 version compatible, with six mail boxes)

· adc: analog-to-digital converter, 10 bits, 500ns conversion speed, 16/8 optional channels

· SPI: peripheral serial interface, synchronous serial port

· SCI: serial communication port, asynchronous serial interface

· speed: 33ns (30mips) instruction cycle, most instructions are single cycle

· 5 external interrupts Digital i/o corner 41

3 TMS320LF2407 DSP excitation regulator hardware composition

dsp excitation regulator adopts a dual channel structure, which is composed of two independent channels with identical hardware. Each channel has two basic operation modes: voltage regulation AVR (automatic voltage regulator) and current regulation FCR (field current regulator). AVR mode takes the generator terminal voltage as the regulation object, and automatically adjusts the excitation current according to the change of generator terminal voltage, so as to achieve the purpose of constant generator terminal voltage operation. FCR mode takes the generator excitation current as the regulating object to realize the constant excitation current operation, which is suitable for operation during commissioning, short-circuit test and other terminal voltage measurement signals

dsp excitation regulator system schematic diagram (see Figure 1 below)

in the figure, a hardware channel of the regulator includes the following parts: Measurement Adapter, active/reactive converter, analog quantity processing unit, isolation input unit, switching quantity input unit, switching quantity output unit, main control unit, pulse amplification unit, keyboard and liquid crystal display unit

the main inputs of the measurement adapter unit are the generator terminal voltage Pt signal, generator terminal current CT signal and excitation current signal; The output is the excitation current signal suitable for microcomputer sampling after processing, as well as the PT signal after voltage reduction and the CT signal converted into voltage signal

active/reactive converter is mainly used to generate active component ICOS and reactive component isin of stator current

the analog input unit is mainly used for rectifying and filtering the terminal voltage, preprocessing the synchronous signal, generating the frequency measurement signal and adapting ICOS and isin, and its output is sent to the main control unit

the isolation input unit is mainly used to isolate and transform the unit switching state and external commands into 24V internal signals through optocoupler devices

the switching value input unit converts the 24V signal of the isolated input unit into a 5V signal suitable for microcomputer input, and realizes the interface with the main control unit

the switching value output unit converts the control command and status signal of the main control unit into the output switching value through its own interface, which is output after photoelectric isolation

the isolation output unit relays the signals of the switching value output unit and operates the external strong current circuit

the main control unit (CPU) is the core of the regulator. It completes the core work of signal synthesis, given value generation, PID operation, phase-shift triggering, channel tracking, serial communication, limit protection, parameter display, modification and storage

after the pulse amplification unit amplifies the double narrow trigger pulse generated by the main control unit, the output value excites the rectifier cabinet, and the trigger pulse triggers the rectifier bridge thyristor after the rectifier cabinet is amplified by the last stage of pulse

keyboard and LCD unit are man-machine interfaces for displaying and modifying data

4 software design of excitation device

the software development tool adopts the DSP development system tds-eep-xds510 based on eep parallel port, which is carried out under the cc/ccs (Code Composer Studio) integrated development environment. The mixed programming of C language and assembly language is used in the programming process

the software program flow chart of PID controller of excitation regulator is set as follows:

software program flow chart

the selection of parameters in the design of PID regulator is very important, and the good ring of parameters is related to the dynamic and static characteristics of the whole system. The tuning of analog PID regulator determines the parameters KP, Ki, KD, Ti of the regulator according to the requirements of the process for control performance. For the tuning of digital PID parameters, in addition to the above parameters, it is also necessary to determine the sampling period T of the system

it is programmed in C language as follows:

include "math.h"

void PID (void)

{int KP, Ki, KD, UreF, u;

float EK, EK1, Ek2, uk1;/*k1 means k-1 */

float tempui, tempup, tempud, tempu, pidout;

ek=u-uref;

tempui=ki*ek;

tempup=kp* (ek-ek1);

tempud=kd* (ek-2*ek1+ek2) ;

tempu=tempui+tempup+tempud;

pidout=tempu+Uk1;

pidout=Uk1;

Ek2=Ek1;

Ek1=Ek;

if(pidout>0)

{...}

}

5 conclusion

prototype capacity specification designed for low-end products:

DC output capacity: 400adc, 250VDC

main functions:

PID automatic control (terminal voltage closed-loop control)

soft excitation, Pt disconnection monitoring, rotor overcurrent limit

under excitation limit, no forced excitation judgment, no forced reduction judgment for most of the utilization of high molecular polymers V/hz limit

pi manual control (rotor current closed-loop control)

control of constant power factor

reference

1 Digital excitation device handout Cui Jianhua, electrical factory of Hebei University of technology Principle, development and application of Tianjin 2001

P chip Zhang Xiongwei, electronic industry press Beijing 2000

2407evm board instruction manual Beijing Wenting company

4 Design and application of modern synchronous generator excitation system Li Jicheng, China Electric Power Press, 2002 (end)

Copyright © 2011 JIN SHI