Method for regulating a generator set

Abstract

The invention concerns a method for regulating the injection of fuel into a heat engine of a generator set including an alternator driven by the heat engine, the alternator including a voltage regulator, the heat engine including a speed regulator having an inlet that can receive an external speed setpoint, the method including the following steps: detecting a variation in torque and kinetic energy from electrical measurements on the alternator, carrying out an action on the input of the setpoint of the voltage regulator and/or the speed regulator, on the basis of the magnitude of the variation in torque relative to the kinetic energy level.

Claims

1. A method for regulating the fuel injection in an engine of an electric generating set comprising an alternator driven by the engine, the alternator comprising a voltage regulator, the engine comprising a speed regulator having an input able to receive an external speed setpoint, the method comprising the following steps: detecting a variation of torque and of kinetic energy by electrical measurements on the alternator; and exerting, as a function of the amplitude of the torque variation relative to the kinetic energy level, an action on the input of the setpoint of the voltage regulator and/or of the speed regulator, the action exerted on the input of the setpoint of the voltage regulator and/or of the speed regulator being such that: if the amplitude of the torque variation relative to the kinetic energy level is below a first predefined threshold, no action is exerted, if the amplitude of the torque variation relative to the kinetic energy level is between the first predefined threshold and a second predefined threshold, the action is exerted on the input of the setpoint of the voltage regulator, and if the amplitude of the torque variation relative to the kinetic energy level is above the second predefined threshold, the action is exerted on the input of the setpoint of the voltage regulator and of the speed regulator.

2. The method as claimed in claim 1, the action exerted on the input of the speed regulator consisting in modifying the speed setpoint value of the engine.

3. The method as claimed in claim 1, the speed setpoint value of the engine being transmitted by the voltage regulator to the speed regulator via a bus, in particular by a series link or an analog signal.

4. The method as claimed in claim 1, the action on the voltage regulator comprising the modification of the value of the current in the pole wheel, so as to temporarily bring the output voltage of the alternator to a value below that before detection of the variation of torque and of kinetic energy, with a view to decreasing the torque level demanded to the engine.

5. The method as claimed in claim 4, the modification of the current in the pole wheel being performed by decreasing the excitation current of the exciter.

6. The method as claimed in claim 4, the modification of the current in the pole wheel being performed by virtue of a pulse width modulation of the voltage across the terminals of the pole wheel.

7. The method as claimed in claim 1, the engine being a turbocharged engine.

8. An electric generating set comprising an engine and an alternator driven by the engine, the electric generating set being suitable for implementing the method for regulating fuel injection such as defined in claim 1.

9. A system for regulating the fuel injection in an engine of an electric generating set comprising an alternator driven by the engine, the alternator comprising a rotor having a pole wheel and a voltage regulator, the engine comprising a speed regulator having an input able to receive an external speed setpoint and a speed sensor, the system being configured to: detect a variation of torque and of kinetic energy by electrical measurements on the alternator; and exert, as a function of the amplitude of the torque variation relative to the kinetic energy level, an action on the input of the setpoint of the voltage regulator and/or of the speed regulator aimed at decreasing the torque demanded to the engine and/or at increasing the speed of the latter, wherein the action exerted on the input of the setpoint of the voltage regulator and/or of the speed regulator being such that: if the amplitude of the torque variation relative to the kinetic energy level is below a first predefined threshold, no action is exerted, if the amplitude of the torque variation relative to the kinetic energy level is between the first predefined threshold and a second predefined threshold, the action is exerted on the input of the setpoint of the voltage regulator, and if the amplitude of the torque variation relative to the kinetic energy level is above the second predefined threshold, the action is exerted on the input of the setpoint of the voltage regulator and of the speed regulator.

10. The system as claimed in claim 9, comprising a controller rotating with the rotor and making it possible to control the current in the pole wheel by a pulse width modulation of the voltage across the terminals of the pole wheel.

Description

(1) The invention will be able to be better understood on reading the detailed description which will follow, of nonlimiting examples of implementation of the latter, and on examining the appended drawing in which:

(2) FIG. 1 represents an electric generating set according to the prior art,

(3) FIG. 2 represents an electric generating set according to the invention,

(4) FIG. 3 is a block diagram illustrating a method according to the invention,

(5) FIG. 4 illustrates various operating spans as a function of the level of kinetic energy and of the variation of torque,

(6) FIG. 5 represents, in isolation, an alternator and a voltage regulator according to the invention, and

(7) FIGS. 6 and 7 represent an alternator variant according to the invention.

(8) An electric generating set according to the prior art comprises, as illustrated in FIG. 1, an engine 2 and an alternator 3, to which a load is applied.

(9) The engine 2 comprises a speed regulator 4 which is for example known per se, comprising an injection computer which computes the injection (or the control of the gases) of the engine so that the rotation speed w is maintained constant as far as possible at a nominal value w.sub.n which depends on the polarity of the alternator and the output current frequency sought, for example 1500 rpm for a frequency of 50 Hz.

(10) The engine 2 comprises a speed sensor 5 that may be, for example, inductive, capacitive or optical. The sensor 5 is for example disposed in front of a toothed ring gear driven in rotation by the engine, and delivers pulses at a frequency proportional to the rotation speed w.

(11) The speed regulator 4 receives the signal from the sensor 5 and computes the appropriate fuel injection level to maintain the speed.

(12) The rotor 19 of an alternator 3 according to the invention may comprise, as illustrated in FIG. 5, a rectifier 17 composed of a full-wave diode bridge, supplying a DC bus 23 on the basis of the exciter armature 7.

(13) The alternator 3 may comprise at the stator 20 an exciter inductor 28, and the main armature winding 27 is linked to a load 30, represented schematically.

(14) The output of an alternator 3 according to the invention supplies for example a three-phase network, the nominal speed w.sub.n of rotation of the engine 2 being for example 1500 rpm, the nominal frequency F.sub.n being equal for example to 50 Hz, and the nominal output voltage U.sub.n between phases of the alternator being for example 400V.

(15) The engine 2 is advantageously a turbocharged engine, but the invention is not limited to a particular engine type.

(16) The speed regulator 4 comprises an input able to receive an external speed setpoint. The invention is not limited to a particular type of input, the latter being able to be digital or analog or communication based.

(17) The alternator 3 comprises, as illustrated in FIG. 2, a voltage regulator 6 which comprises a regulating system designed to detect a variation of the load, on the basis of a detection of a variation of the torque and/or of kinetic energy of the engine 2. The voltage regulator 6 may be a digital regulator, but the invention is not limited to a particular voltage regulator type.

(18) The electric generating set 1 may comprise, as in the example described, a user interface 31 which communicates with the voltage regulator 6 and the speed regulator 4, for example by way of an information exchange bus, for example by a CAN, Mod Bus, CAN open, J1939, proprietary, or other link protocol. Thus, the voltage regulator 6 may transmit information to the speed regulator 4, and in particular change the speed setpoint value.

(19) The user interface 31 may comprise a control screen, for example a network analyzer or an installation supervisor. The user interface 31 may perform for example the reading and the display of the values of voltage, current, power and temperature of the alternator 3. The interface 31 may make it possible to adjust the voltage, the power factor, the power unit, the manual operating point, or else the gains of each regulating loop, and the parameters of the aid to the optimization of the responses in the transient regime, if appropriate.

(20) The user interface 31 also makes it possible to adjust limiting parameters, diverse options, and parameters dependent on the type of alternator used.

(21) The voltage regulator 6 may be supplied by a generator having permanent magnets 9 or by any other means.

(22) The voltage regulator 6 comprises a computer 12, for example having a microprocessor, represented in FIG. 5, which determines the current to be applied in the pole wheel 8 to maintain the amplitude of the voltage at a setpoint value which by default is the nominal voltage U.sub.n.

(23) The modification of the current in the pole wheel 8 is performed in particular by decreasing the excitation current of the exciter, the voltage regulator 6 acting on this current in a conventional manner.

(24) In a variant, the modification of the current in the pole wheel 8 is performed by virtue of a pulse width modulation of the voltage across the terminals of the pole wheel.

(25) The voltage regulator 6 computes, during a step 101 represented in FIG. 3, the levels of torque and of kinetic energy. These levels are computed by virtue of information relating to the electrical quantities at the output of the alternator 3, for example on the basis of the voltage U between output phases of the alternator and of the current passing through the main armature winding 27 of the stator 20, this current being determined by virtue of a current sensor 11 represented in FIG. 5.

(26) In the course of the operation of the electric generating set, the torque value is examined to determine whether it has changed, this corresponding to step 102 of the diagram of FIG. 3. If appropriate, the amplitude of the torque variation is evaluated relative to the kinetic energy level, in a step 103, so as to determine whether an action must be exerted on the input of the speed regulator and/or of the voltage regulator.

(27) If the torque variation is low, or if the kinetic energy level is sufficiently high, no action is exerted. The voltage regulator 6 then recomputes the levels of torque and of kinetic energy, as indicated at 104 in FIG. 3.

(28) If the amplitude of the torque variation relative to the kinetic energy level is below a predefined threshold, an action is exerted on the voltage regulator 6 alone, during a step 105.

(29) Finally, if the amplitude of the torque variation relative to the kinetic energy level is above the predefined threshold, an action is exerted both on the input of the speed regulator 4 and on the voltage regulator 6, during a step 106.

(30) The predefined threshold depends on the characteristics of the engine 2 and those of the alternator 3.

(31) Various actions which depend on the amplitude of the torque variation Δ relative to the kinetic energy level E are illustrated in FIG. 4. Region A corresponds to a fairly low variation of torque Δ, and whatever the kinetic energy level E, no action will be exerted. Region B corresponds to a mean variation of torque Δ, and an action will be exerted on the voltage regulator 6 only. Region C corresponds to a high variation of torque Δ, and whatever the kinetic energy level E, an action will be exerted both on the input of the speed regulator 4 and on the voltage regulator 6.

(32) In case of an increase in the load, the action on the voltage regulator 6 comprises the modification of the value of the current in the pole wheel 8, so as to temporarily bring the output voltage U of the alternator 3 to a value below that before detection of the variation of torque and of kinetic energy, with a view to decreasing the torque level demanded to the engine 2.

(33) Once the power of the engine has increased and the rotation speed w increases, the value of the current in the pole wheel 8 may be modified again, so as to restore the value of the output voltage U to that before the variation of torque, to a nominal operating point.

(34) The invention is not limited to the example which has just been described with reference to FIGS. 2 to 5.

(35) In the variant represented in FIGS. 6 and 7, the rotor 19 comprises an onboard communication system, and the DC bus 23 is linked to a switching system 18. A filtering capacitor 21 may be provided.

(36) The switching system 18 may be composed, for example, as illustrated of a free wheel diode 26 and of a switchable electronic component 25, such as an IGBT transistor.

(37) A controller 13 controls the switching system 18 so as to regulate, when necessary, by pulse width modulation, the voltage in the pole wheel 8. The duty cycle β of the pulse width modulation is dependent among other things on the output voltage of the main machine, so as to maintain as far as possible the voltage delivered by the alternator 3 at the desired value.

(38) The rotor 19 comprises in the example illustrated a current sensor 10 to measure the current in the pole wheel 8. The value of the current thus measured is transmitted to the controller 13.

(39) The voltage regulator 6 at the stator 20 is supplied by a power supply 32, and the exciter inductor 28 is coiled, in the example described. An HF wireless communication system is disposed between the controller 13 of the rotor 19 and the voltage regulator 6 of the stator 20 of the alternator 3. The wireless communication system is composed of a transmission module 14 disposed at the rotor 19, of a transmission module 29 disposed at the stator 20, and of wireless transmission pathways 15 linking said modules.

(40) The value of the current in the pole wheel 8, measured by the current sensor 10 of the rotor 19, is transmitted to the voltage regulator 6 of the stator 20 by the wireless communication system 14, 15, 29.