APPARATUS AND METHOD OF SENSORLESS CONTROL FOR SYNCHRONOUS GENERATOR

• US 20030081434A1
• Filed: 03/19/2002
• Published: 05/01/2003
• Est. Priority Date: 10/25/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Futami, Motoo, Kikuchi, Akira, Sugawara, Naoshi, Miyazaki, Kouichi, Sugiura, Yasuyuki
• Granted Patent: US 6,567,282 B1
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: H02P 21/26 Rotor flux based control
• CPC Class Codes: H02P 2201/03 AC-DC converter stage controlled to provide a defined DC link voltage
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence

Abstract

An apparatus for controlling a synchronous generator having a converter. A voltage detector detects a terminal voltage of a stator of the synchronous generator. A current detector detects a current flowing through the stator. A rotor position estimating part estimates a rotor position of the synchronous generator from the detected voltage and current. An active power detector detects a active power of the synchronous generator. A reactive power detector detects a reactive power of the synchronous generator or a terminal voltage detector detects an effective value of a terminal voltage of the stator. An active power controller adjusts a q-axis current command to control the active power, and a reactive power controller or terminal voltage controller adjusts a d-axis current command to control the reactive power or terminal voltage.

Claims

1. An apparatus for controlling a synchronous generator which comprises a converter connected to a stator of said synchronous generator and an inverter connected to said converter and also connected to a power system and wherein said converter converts a power of a variable frequency generated by said synchronous generator to a D.C. power, and said inverter converts said D.C. power to an A.C. power of a fixed frequency, said converter includes a voltage detector for detecting a terminal voltage of the stator of said synchronous generator, a current detector for detecting a current flowing through the stator of said synchronous generator, and rotor position estimating means for estimating a rotor position of said synchronous generator from a voltage detected by said voltage detector and a current detected by said current detector, said rotor position estimating means calculates a d-axis component of a voltage induced in said synchronous generator in a d-q axis coordinate system determined by a rotor position during estimation and controls the d-axis component of said induced voltage to zero to estimate the rotor position, said rotor position estimating means includes an active power detector for detecting a active power of an output of said synchronous generator and a reactive power detector for detecting a reactive power of the output of said synchronous generator or a terminal voltage detector for detecting an effective value of the terminal voltage of the stator of said synchronous generator, said rotor position estimating means also includes a active power controller for controlling the active power of the output of said synchronous generator with use of the active power value detected by said active power detector and an active power controller for controlling the reactive power of the output of said synchronous generator or a terminal voltage controller for controlling the terminal voltage of said synchronous generator with use of the terminal voltage value detected by said terminal voltage detector, said active power controller adjusts a q-axis current command on the d-q axis coordinate system determined by said rotor position estimating means to control the active power of said synchronous generator, said reactive power controller or said terminal voltage controller adjusts a d-axis current command on the d-q axis coordinate system determined by said rotor position estimating means to control the reactive power or terminal voltage of said synchronous generator.

2. An apparatus for controlling a synchronous generator as set forth in claim 1, further comprising an angular velocity estimator for receiving a difference between a d-axis component of the induced voltage of said synchronous generator on the d-q axis coordinate system determined by said rotor position estimating means and zero, and wherein said angular velocity estimator forms a proportional integration control system.

3. An apparatus for controlling a synchronous generator as set forth in claim 2, wherein an output of said angular velocity estimator is limited by a limiter and upper and lower limit values of said limiter are determined by an operating speed range of said synchronous generator.

4. An apparatus for controlling a synchronous generator as set forth in claim 3, further comprising a rotor position estimator for receiving an estimated angular velocity value as an output of said angular velocity estimator, and wherein said rotor position estimator forms an integrator.

5. A method for controlling a synchronous generator in an apparatus which comprises a converter connected to a stator of said synchronous generator and an inverter connected to said converter and also connected to a power system and wherein said converter converts a power of a variable frequency generated by said synchronous generator to a D.C. power, and said inverter converts said D.C. power to an A.C. power of a fixed frequency, said converter includes rotor position estimating means, reactive and active power controllers and a terminal voltage controller;

said method comprising the steps of;

estimating by said rotor position estimating means a rotor position of said synchronous generator from an induced voltage of said synchronous generator and a current of the generator flowing through the stator of the generator;

calculating a d-axis component of a voltage induced in said synchronous generator in a d-q axis coordinate system determined by a rotor position during estimation and controlling a d-axis component of said induced voltage to zero to estimate the rotor position;

controlling by said active power controller a detected active power value of the output of said synchronous generator;

controlling by said reactive power controller or terminal voltage controller an detected reactive power value of the output of said synchronous generator or a detected terminal voltage value of said synchronous generator;

adjusting by said active power controller a q-axis current command on the d-q-axis coordinate system determined by said rotor position estimating means to control a active power of said synchronous generator; and

adjusting by said reactive power controller or said terminal voltage controller a d-axis current command on the d-q-axis coordinate system determined by said rotor position estimating means to control a reactive power or a terminal voltage of said synchronous generator.