CLOSED-LOOP CONTROL DEVICE FOR CLOSED-LOOP CONTROL OF A POWER ASSEMBLY INCLUDING AN INTERNAL COMBUSTION ENGINE AND A GENERATOR HAVING AN OPERATIVE DRIVE CONNECTION TO THE INTERNAL COMBUSTION ENGINE, CLOSED-LOOP CONTROL ARRANGEMENT HAVING SUCH A CLOSED-LOOP CONTROL DEVICE, POWER ASSEMBLY AND METHOD FOR CLOSED-LOOP CONTROL OF A POWER ASSEMBLY

Abstract

A closed-loop control device, for closed-loop control of a power assembly including an internal combustion engine and a generator having an operative drive connection to the internal combustion engine, includes: the closed-loop control device which is configured, in a first functional state, for: detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); using a control rule for determining the target speed (n.sub.soll); and being operatively connected to an open-loop control device of the internal combustion engine in such a way that the target speed (n.sub.soll) can be transmitted by the closed-loop control device to an open-loop control device.

Claims

1. A closed-loop control device for closed-loop control of a power assembly including an internal combustion engine and a generator having an operative drive connection to the internal combustion engine, the closed-loop control device comprising: the closed-loop control device which is configured, in a first functional state, for: detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency (f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); using a control rule for determining the target speed (n.sub.soll); and being operatively connected to an open-loop control device of the internal combustion engine in such a way that the target speed (n.sub.soll) can be transmitted by the closed-loop control device to an open-loop control device.

2. The closed-loop control device according to claim 1, wherein the closed-loop control device is configured for adapting the control rule used to determine the target speed (n.sub.soll) as a function of at least one adaptation variable, and wherein the at least one adaptation variable is selected from a group consisting of a droop variable (d) and a torque variable.

3. The closed-loop control device according to claim 2, wherein the torque variable is calculated by the open-loop control device of the internal combustion engine.

4. The closed-loop control device according to claim 2, wherein the closed-loop control device is configured for adapting the control rule by determining a proportional coefficient (k.sub.p.sup.f) of the control rule in such a way that a predetermined loop gain (v.sup.f) of an open control loop is constant.

5. The closed-loop control device according to claim 4, wherein the closed-loop control device is configured for determining the proportional coefficient (k.sub.p.sup.f) as a function of the droop variable (d) and the torque variable.

6. The closed-loop control device according to claim 4, wherein the closed-loop control device (3) is configured for selecting the proportional coefficient (k.sub.p.sup.f) only as a function of the predetermined loop gain (v.sup.f).

7. The closed-loop control device according to claim 1, wherein the closed-loop control device is configured for filtering an actual frequency (f.sub.ist)which is instantaneousof the generator and for using the actual frequency (f.sub.ist)which is filteredas the generator frequency (f.sub.G) which is detected.

8. The closed-loop control device according to claim 1, wherein the closed-loop control device is configured for, in a second functional state, predefining the target speed (n.sub.soll) to be constant.

9. The closed-loop control device according to claim 8, wherein the closed-loop control device is configured for selecting the droop variable (d) to be zero.

10. A closed-loop control arrangement for closed-loop control of a power assembly including an internal combustion engine and a generator having an operative drive connection to the internal combustion engine, the closed-loop control arrangement comprising: a closed-loop control device for closed-loop control of a power assembly, the closed-loop control device being configured, in a first functional state, for: detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency (f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); using a control rule for determining the target speed (n.sub.soll); and being operatively connected to an open-loop control device of the internal combustion engine in such a way that the target speed (n.sub.soll) can be transmitted by the closed-loop control device to an open-loop control device; and the open-loop control device which is operatively connected to the closed-loop control device for direct control of the internal combustion engine, the closed-loop control device being configured for transmitting the target speed (n.sub.soll) to the open-loop control device.

11. The closed-loop control arrangement according to claim 10, wherein the open-loop control device is configured for determining at least one torque variable and for transmitting the at least one torque variable to the closed-loop control device, and wherein the closed-loop control device is configured for receiving the at least one torque variable from the open-loop control device.

12. The closed-loop control arrangement according to claim 11, wherein the open-loop control device is configured for determining, as the at least one torque variable, a variable which is selected from a group consisting of: a target torque (M.sub.soll) and an integral component (M.sub.soll.sup.I) of a speed controller of the open-loop control device.

13. The closed-loop control arrangement according to claim 12, wherein the target torque (M.sub.soll) is filtered.

14. A power assembly, comprising: an internal combustion engine; a generator including an operative drive connection to the internal combustion engine; and one of: (a) a closed-loop control device for closed-loop control of the power assembly, the closed-loop control device being configured, in a first functional state, for: detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency (f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); using a control rule for determining the target speed (n.sub.soll); and being operatively connected to an open-loop control device of the internal combustion engine in such a way that the target speed (n.sub.soll) can be transmitted by the closed-loop control device to an open-loop control device; and (b) a closed-loop control arrangement for closed-loop control of the power assembly, the closed-loop control arrangement including: a closed-loop control device for closed-loop control of the power assembly, the closed-loop control device being configured, in a first functional state, for: detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency (f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); using a control rule for determining the target speed (n.sub.soll); and being operatively connected to an open-loop control device of the internal combustion engine; and the open-loop control device which is operatively connected to the closed-loop control device for direct control of the internal combustion engine, the closed-loop control device being configured for transmitting the target speed (n.sub.soll) to the open-loop control device; wherein the closed-loop control device or the closed-loop control arrangement is operatively connected to the internal combustion engine and the generator of the power assembly.

15. A method for closed-loop control of a power assembly including an internal combustion engine and a generator having an operative drive connection to the internal combustion engine, the method comprising the steps of: in a first operating mode, detecting a generator frequency (f.sub.G) of the generator as a controlled variable; determining a control deviation (e.sub.f) as a difference between the generator frequency (f.sub.G) which is detected and a target generator frequency (f.sub.soll); determining a target speed (n.sub.soll) as a manipulated variable for controlling the internal combustion engine as a function of the control deviation (e.sub.f); and determining the target speed (n.sub.soll) based on a control rule.

16. The method according to claim 15, wherein the step of determining the target speed (n.sub.soll) based on the control rule includes calculating the target speed (n.sub.soll) based on the control rule.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0074] FIG. 1 shows a first schematic representation of an exemplary embodiment of a power assembly with an exemplary embodiment of a control device;

[0075] FIG. 2 shows a second schematic representation of the exemplary embodiment of the power assembly according to FIG. 1;

[0076] FIG. 3 shows a third schematic representation of the exemplary embodiment of the power assembly according to FIG. 1;

[0077] FIG. 4 shows a detailed representation of a controller for frequency control;

[0078] FIG. 5 shows a detailed representation of an embodiment of a method for calculating the proportional coefficient for the frequency control;

[0079] FIG. 6 shows a schematic, diagrammatic representation of the mode of operation of an embodiment of a method for closed-loop control of a power assembly.

[0080] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one embodiment of the invention, and such exemplification are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0081] FIG. 1 shows a first schematic representation of an exemplary embodiment of a power assembly 1 with a first exemplary embodiment of a closed-loop control device 3. The power assembly 1 has an internal combustion engine 5 and a generator 9 which has an operative drive connection to the internal combustion engine 5 via a shaft 7 shown schematically. The closed-loop control device 3 is operatively connected to the internal combustion engine 5 on the one hand and to the generator 9 on the other.

[0082] In particular, the closed-loop control device 3 is set up for closed-loop control of the power assembly 1, wherein it is set up to detect a generator frequency f.sub.G of the generator 9 as a controlled variable, to determine a control deviation as the difference between the detected generator frequency f.sub.G and the target generator frequency f.sub.soll, and to determine a target speed n.sub.soll as a manipulated variable for controlling the internal combustion engine 5 as a function of the control deviation. The closed-loop control device 3 is also designed to use a control rule for determining the target speed n.sub.soll. The closed-loop control device 3 is designed as a generator controller and is operatively connected to an open-loop control device 11 of the internal combustion engine 5 in such a way that the target speed n.sub.soll can be transmitted by the closed-loop control device 3 to the open-loop control device 11. This also enables, at the same time, particularly robust frequency control and versatile usability of the closed-loop control device 3, in particular with a multiplicity of power assemblies 1.

[0083] The closed-loop control device 3 and the open-loop control device 11 together form a closed-loop control arrangement 13 for closed-loop control of the power assembly 1. The open-loop control device 11 is optionally designed as an engine controller, in particular as an engine control unit (ECU).

[0084] In particular, the open-loop control device 11 is set up to calculate at least one torque variable and to transmit it to the closed-loop control device 3, wherein the closed-loop control device 3 is set up to receive the at least one torque variable from the open-loop control device 11.

[0085] In addition, the open-loop control device 11 is optionally set up to determine a variable as the torque variable which is selected from a group consisting of aoptionally filteredtarget torque M.sub.soll and an integral component of a speed controller 21shown in FIG. 2of the closed-loop control device 11, in particular an integral component M.sub.soll.sup.I of the target torque M.sub.soll.

[0086] Optionally, another input variable of the closed-loop control device 3 is a droop variable d.

[0087] The open-loop control device 11 also has the target speed n.sub.soll and a detected speed n.sub.ist as input variables. From this, the open-loop control device 11 calculates a speed control deviation. Lastly, the open-loop control device 11 uses this speed control deviation to calculate an energization duration BD for controlling the fuel injection valves of the internal combustion engine 5. Optionally, the open-loop control device 11 first calculates the target torque M.sub.soll from the speed control deviation and, from this, in turn, the energization duration BD.

[0088] FIG. 2 shows a second schematic representation of the exemplary embodiment of the power assembly 1 according to FIG. 1, in particular in the form of a block diagram.

[0089] Like and functionally similar elements are provided with the same reference signs in all figures, and therefore reference is made to the previous description in each case.

[0090] Optionally, an actual frequency f.sub.ist detected at the generator 9 is filtered in a frequency filter 15, and the filtered actual frequency f.sub.ist is used as the detected generator frequency f.sub.G. The frequency filter 15 is optionally a PT.sub.1 filter or a mean value filter. The frequency filter 15 is optionally part of the closed-loop control device 3, which also has a frequency controller 17 that calculates the target speed n.sub.soll from the control deviation e.sub.f as the difference between the target generator frequency f.sub.soll and the detected generator frequency f.sub.G. The target speed n.sub.soll can be an absolute target speedwithout reference to a nominal speed n.sub.Nor a relative target speedin particular as a difference from the nominal speed n.sub.N. If the target speed n.sub.soll is a relative speed, the nominal speed n.sub.N is added to the output of the frequency controller 17 in the open-loop control device 11, as shown by dashed lines.

[0091] The open-loop control device 11 has a speed filter 19, which is optionally designed as a PT.sub.1 filter or mean value filter. A measured speed n.sub.mess, optionally used to calculate the speed control deviation e.sub.n, is obtained by filtering the actual speed n.sub.ist measured directly at the internal combustion engine 5 using the speed filter 19. The open-loop control device 11 also has the speed controller 21, which calculates the target torque M.sub.soll from the speed control deviation e.sub.n and optionally, from this,in a manner not shownthe energization duration BD. A controlled system 23 of the speed control loop assigned to the speed controller 21 includes the internal combustion engine 5 and the generator 9.

[0092] In the text which follows, the meaning of the droop variable d will be explained in more detail:

[0093] The droop variable d is optionally used to calculate a differential speed ?n, wherein an effective target speed n.sub.eff is calculated by adding the differential speed ?n to the target speed n.sub.sollalternatively the nominal speed n.sub.N. The effective target speed n.sub.eff is used to calculate the speed control deviation e.sub.n by subtracting the measured speed n.sub.mess from the effective target speed n.sub.eff. The differential speed ?n is calculated in a calculation block 25. The input variables of the calculation block 25 are the integral component M.sub.soll.sup.I, calculated by the speed controller 21, of the target torque M.sub.soll, the droop variable d, the full-load torque M.sub.V, and a nominal speed n.sub.N for the internal combustion engine 5, wherein the nominal speed n.sub.N can be 1500 min.sup.?1, for example. The differential speed ?n is optionally calculated according to the following equation:

[00023]$\begin{array}{cc}?n=n_{N}d\frac{M_V-M_{\mathrm{soll}}^I}{M_V}.& \left(44\right)\end{array}$

[0094] In a first functional state of the control device 3, which optionally corresponds to island parallel operation or grid parallel operation of the power assembly 1, the droop variable d is optionally set to a finite value, in particular in the single-digit percentage range, optionally to a maximum of 8%, optionally 4%. The droop variable d can be preset, i.e., in particular parameterized, by a user of the power assembly 1 or the closed-loop control device 3. In a second functional state of the control device 3, which is associated with island operation of the power assembly 1, the droop variable d is optionally set to zero, both in the closed-loop control device 3 and in the open-loop control device 11. If the droop variable d is zero, the differential speed ?n also vanishes, so that the effective target speed n.sub.eff is then equal to the target speed n.sub.soll.

[0095] If the droop variable d is different from zero, the result is as follows: If the internal combustion engine 5 is running at full load, the integral component M.sub.soll.sup.I of the target torque M.sub.soll is equal to the full-load torque M.sub.V, so that the differential speed ?n is zero. If, on the other hand, the internal combustion engine 5 is idling, the integral component M.sub.soll.sup.I is zero and the differential speed ?n is equal to the percentage of the nominal speed n.sub.N determined by the droop variable d. If the nominal speed is 1500 min.sup.?1 and the droop variable d is 4%, the value of the differential speed ?n therefore varies between 0 min.sup.?1 at full load and 60 min.sup.?1 at idling speed.

[0096] FIG. 3 shows a third schematic representation of the power assembly 1 according to FIG. 1, in this case as a linearized block diagram. The individual controllers are represented by transfer blocks with correspondingly assigned transfer functions. In contrast to FIG. 2, the controlled system 23 in FIG. 3 is shown divided into two transfer blocks, namely a transfer block assigned to the internal combustion engine 5, characterized by the transfer function G.sub.s.sup.n(s), with the target torque M.sub.soll as the input variable and the actual speed n.sub.ist as the output variable, and a transfer block assigned to the generator 9, characterized by the transfer function G.sub.s.sup.f(s), with the same input variable, namely the target torque M.sub.soll, and the actual frequency f.sub.ist as output variable. The speed controller 21 is represented by a first multiplication element 27 for calculating a proportional component M.sub.soll.sup.P of the target torque M.sub.soll by multiplication with the speed proportional coefficient k.sub.p.sup.n and a first integration element 29 for calculating the integral component M.sub.soll.sup.I of the target torque M.sub.soll by multiplication with a term

[00024]$\frac{1}{{?}_n^{n}s},$

with the reset time ?.sub.n.sup.n and the complex variable s. Thus, the speed controller 21 has a PI transmission behavior here, since the first multiplication element 27 has a proportional transmission behavior and the first integration element 29 has an integral transmission behavior. The calculation block 25 is given a negative sign by the linearization here, so that the differential speed ?n calculated in the calculation block 25 is now subtracted from the target speed n.sub.soll. Due to the linearization, the differential speed ?n is calculated in the calculation block 25 according to the following modified equation:

[00025]$\begin{array}{cc}?n=n_{N}d\frac{M_{\mathrm{soll}}^I}{M_V}.& \left(45\right)\end{array}$

[0097] FIG. 4 shows a schematic representation of a detail of the frequency controller 17 according to FIG. 3, which is optionally implemented as a PI controller. The control deviation e.sub.f is first multiplied here by the proportional coefficient k.sub.p.sup.f so that a proportional component n.sub.soll.sup.P for the target speed n.sub.soll is obtained. In a second integration element 31, the proportional component n.sub.soll.sup.P, by division by the product of the reset time ?.sub.n.sup.f with the complex variable s, calculates an integral component n.sub.soll.sup.I for the target speed n.sub.soll, which is then added to the proportional component n.sub.soll.sup.P. This results in the target speed n.sub.soll as output variable. The transfer function of the frequency controller 17 is therefore given by:

[00026]$\begin{array}{cc}{G}_r^f\left(s\right)=k_p^f\left(1+\frac{1}{T_n^{f}s}\right).& \left(46\right)\end{array}$

[0098] The calculation of the proportional coefficient k.sub.p.sup.f is optionally calculated according to equation (1).

[0099] The control rule is adapted here in particular by determining the proportional coefficient k.sub.p.sup.f in such a way that the predetermined loop gain v.sup.f is constant, in particular remains constant.

[0100] FIG. 5 shows a detailed representation of an embodiment of a method for calculating the proportional coefficient k.sub.p.sup.f for the frequency control according to equation (1). In a second multiplication element 33, the predetermined loop gain v.sup.f is, to this end, multiplied by the factor 900 and an output of a summation element 35. The proportional coefficient k.sub.p.sup.f is obtained as the output of the second multiplication element 33. In the summation element 35, the number 1 is added to the output of a third multiplication element 37. In the third multiplication element 37, the droop variable d is multiplied by the torque M.sub.stat and the reciprocal value of the full-load torque M.sub.V. The reciprocal value of the full-load torque M.sub.V is formed from the full-load torque M.sub.V in a division element 39.

[0101] The torque M.sub.stat can be determined in two different ways: On the one hand, from the integral component M.sub.soll.sup.I delayed by a sampling step ?.sub.a. In this case, a switch 41 provided for switching between the two calculation types is arranged in the upper switch position according to FIG. 5.

[0102] Alternatively, the torque M.sub.stat can be calculated from the target torque M.sub.soll calculated by the open-loop control device 11. This is also first delayed by a sampling step ?.sub.a and then filtered by a filter 43, wherein the torque filter 43 is optionally a PT.sub.1 filter. This calculation is active when the switch 41 is in the lower switch position according to FIG. 5.

[0103] FIG. 6 shows a schematic, diagrammatic representation of the mode of operation of an embodiment of a method for closed-loop control of the power assembly 1. The method is illustrated here using five time graphs. In particular, a first time graph at a) shows a time curve of the actual frequency f.sub.ist of the generator 9. A second time graph at b) shows a time curve of the target speed n.sub.soll in the unit min.sup.?1. A third time graph at c) shows the time curve of the integral component M.sub.soll.sup.I of the target torque M.sub.soll. A fourth time graph at d) shows the time curve of the speed n of the internal combustion engine 5. Lastly, a fifth time graph at e) shows the time curve of the differential speed ?n.

[0104] In the first time graph at a), a first, dashed curve represents the course of the constant target frequency f.sub.soll of the generator 9, which is optionally 50 Hz. At a first point in time t.sub.1 a load is switched on, which causes the actual frequency f.sub.ist, which is represented by a second, solid curve, to drop. Subsequently, the actual frequency f.sub.ist rises again, reaches the value of the target frequency f.sub.soll again, overshoots and finally settles at the value of the target frequency f.sub.soll at a second point in time t.sub.2.

[0105] At a third point in time t.sub.3, the load is dropped again. The actual frequency f.sub.ist increases as a result and finally settles again at the target frequency f.sub.soll at a fourth point in time t.sub.4.

[0106] In the time graphs shown, the internal combustion engine 5 is operated in grid parallel operation. The set droop variable is 4%.

[0107] The second time graph at b) shows the time curve of the target speed n.sub.soll. The differential speed ?n is shown in the fifth time graph. The load connection shown in the first time graph represents the connection of a 50% loadbased on full loadand this 50% load is to be dropped again when the load is switched off. Up to the first point in time t.sub.1, the internal combustion engine 5 is in a load-free state, resulting in a value of 60 min.sup.?1 for the differential speed ?nas shown in the fifth time graph. Since a sum of the target speed n.sub.soll and the differential speed ?n at a target frequency for the generator 9 of 50 Hz must result in an effective target speed n.sub.eff of 1500 min.sup.?1, the target speed n.sub.soll up to the first point in time t.sub.1 is 1440 min.sup.?1. At the first point in time t.sub.1, the 50% load is switched on and is present at the second point in time t.sub.2. The differential speed ?n is therefore 30 min.sup.?1 at the second point in time. The target speed n.sub.soll is therefore 1470 min.sup.?1 at the second point in time t.sub.2. The target speed n.sub.soll therefore increases from 1440 min.sup.?1 to 1470 min.sup.?1 from the first point in time t.sub.1 to the second point in time t.sub.2. By contrast, the differential speed ?n drops from 60 min.sup.?1 to 30 min.sup.?1 during this period.

[0108] The integral component M.sub.soll.sup.I shown in the third time graph at c) is 0 Nm up to the first time t.sub.1, as no load is applied. Starting from the first time t.sub.1, it then increases up to the second time t.sub.2 to the value 5000 Nm, which corresponds to a load of 50% of the full load torque M.sub.V in the exemplary embodiment shown here.

[0109] In the fourth time graph at d), the measured speed n.sub.mess and the effective target speed n.sub.eff are shown one above the other. Both values are typically constant in grid parallel operation and identical to 1500 min.sup.?1.

[0110] Switching off the load at the third time t.sub.3 results in the target speed n.sub.soll in the second time graph being reduced back to its initial value of 1440 min.sup.?1. The integral component M.sub.soll.sup.I according to the third time graph is reduced again to the value 0 Nm. The differential speed ?n shown in the fifth time graph is increased again to the value of 60 min.sup.?1.

[0111] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.