WO2016102675A1

WO2016102675A1 - Optimal dispatch

Info

Publication number: WO2016102675A1
Application number: PCT/EP2015/081172
Authority: WO
Inventors: Allan Schmidt; Søren Dahl CHRISTENSEN; Claes Høll STERREGAARD
Original assignee: Deif A/S
Priority date: 2014-12-23
Filing date: 2015-12-23
Publication date: 2016-06-30

Abstract

This invention relates to a method of controlling and a generator controller configured to control a dispatch of power from a power plant with more than one genset, each genset configured to dispatch power up to a rated maximum limit and the power plant to dispatch a total power at or above a set point to cover a given load of a grid, wherein the controller is configured to determine a number of gensets required to cover the set point and to control the determined number of gensets to dispatch power each at their maximum rated limitation.

Description

Optimal Dispatch Field of the Invention

This invention relates to a generator controller configured to control a dispatch of power from a power plant with more than one genset, each genset configured to dis- patch power up to a rated maximum limit and the power plant to dispatch a total power at or above a set point to cover a given load of a grid, wherein the controller is configured to determine a number of gensets required to cover the set point and to control the determined number of gensets to dispatch power each at their maximum rated limitation. Background of the Invention

Gensets or power modules or such arranged as a power plant may dispatch power with a certain efficiency. Improvements in efficiency will save resources and/or provide better utilization of equipment.

Objective of the Invention

It is an object of the invention to provide improved dispatch of power from a genset or a power plant comprising more than one genset. Improvements may be understood by considering run hours, production and fuel consumption and it is desired to improve or maximise the dispatch during operation according to one or more of such measures.

Description of the Invention

An object of the invention is achieved by a generator controller configured to control a dispatch of power from a power plant with more than one genset, each genset configured to dispatch power up to a rated maximum limit and the power plant to dispatch a total power at or above a set point to cover a given load of a grid, wherein the controller is configured to determine a number of gensets required to cover the set point and to control the determined number of gensets to dispatch power each at their maximum rated limitation.

This results in operating the power modules or gensets at improved or maximum dispatch, and improved or best combination of run hours, fuel consumption and produc- tion is achieved. The customer and the owner of the plant use these figures or measures to determine the quality of operation of the plant. Hence better utilization of the equipment, e.g. better efficiency and better economy is achieved. One effect is that that the gensets are driven at their full load and run at their optimal consumption (g/kWh or l/kWh). This means the customer receives the full amount of power from the running gensets in plant. Comparison of fuel consumption data between the owner and the customer may also be easier. A person skilled in the art may acknowledge different metrics and may work with a maximum heat rate (kJ/kWh).

In an embodiment the generator controller may further be configured to accept a derating of the genset caused by an abnormality in the genset and configured to maintain the determined number of gensets to dispatch power until the total power plant power is below the set point before determining a new number of gensets each to dispatch power each at their maximum rated limitation.

An abnormality may be a state that causes a derating of the genset and can be related to any measured or calculated values. Often an abnormality related to temperatures or (differential) pressures. Some examples are given here: high lubricating oil temp, high coolant temp, high intercooler temp and high ambient air temp. The derating may also be caused by high differential pressures across filters such as fuel filters and air filters.

In an embodiment the generator controller may be configured to store and process an operating characteristic of an alternator of the genset and configured to operate the genset within the limits of the operating characteristic.

The operation characteristic may be the capability curve of the alternator. The characteristic or curve may be supplied as tabulated values, as a function or as any other representation.

Thus, the generator may be operated to its full potential rather than be operated at fixed or limited operational point determined by the grid or grid codes. The use of the operation characteristic or the capability curve in the controller allows further improvement of the outlined advantages. At the same time it will maximize the power generated by the generator whilst stabilising the grid. Finally, it will increase protection of the generator by avoiding operation in regimes that will develop critical temperatures in the windings, which may also be caused due to asymmetric operation of the generator.

In particular a generator has been operated at a fixed operation point to avoid coming close to a point of no return where insulation layers on generator windings alter or even burn through.

The controller may keep track of a current operation point in relation to the operating characteristics. In an embodiment the generator controller may be configured to be embedded in one or more gensets.

Hence the disclosed dispatch, the optimal dispatch functionality, may be controlled on all levels in the plant. There may be controllers on one or more of the controller levels, i.e. on the generators, a controller per a number of grouped generators and on the plant level. This may depend on plant design and complexity.

The dispatch functionality or implementation can be adjusted in the individual generators) to be controlled from the individual generator or from the higher level control- ler. If it is adjusted to be controlled from a higher level controller and it does not receive settings from the higher level controller, then it will not use the optimal dispatch function. It the generator controller receives settings from the higher level controller it uses the settings of that particular controller. The controller that includes a number of the gensets can be adjusted to its own individual settings or it can be adjusted to receive settings from the higher level controller.

If the controller is adjusted to be controlled from a higher level controller and it does not receive settings from the higher level controller then it does not send optimal dis- patch settings to the generator controllers, and the generators will not work in optimal dispatch mode. It the controller receives settings from the higher level controller it uses the settings of that particular controller. The highest level controller may send the optimal dispatch settings to the lower level controllers making them use the transmitted optimal dispatch set point on the condition that the function to listen to the higher level is enabled

The controller may be configured with different operational modes. There may be an OFF -mode, an ON-mode, or a superior mode. In OFF-mode a controller may be switched off. In ON-mode a controller may use its own set-point. In superior mode a controller may "listen" to a set of set-points from a higher level controller.

An object may be achieved by a power plant with more than one genset and with a controller as disclosed.

An object may be achieved by a method of dispatching power from a power plant with more than one genset, each configured to dispatch power up to a rated maximum limit and the power plant to dispatch a total power at or above a set point to cover a given load on a grid, the method comprising actions of determining the set point; determining the number gensets required to cover set point; and dispatching power from the determined number of gensets each operating at their maximum rated limitation.

The disclosed method comprises actions. The action of determining the set point may require that the dispatch set point is manually adjusted in the controller or the optimal dispatch set-point may also be adjusted in the controller should it deviate from 100.

The action of determining the number gensets required to cover set point may require that the number of gensets used to cover the set point is determined based on the re- quested spinning reserve that is adjusted in the controller meaning the set point plus a spinning reserve compared to the groups of gensets/gensets in a prioritized manner. The action of dispatching power from the determined number of gensets each operating at their maximum rated limitation may require that the gensets are dispatching power according to their maximum limitation when they are connected to the busbar. In an embodiment of the method of dispatching power from a power plant may further comprise of actions of detecting derating of a genset caused by an abnormality. There may be an action of accepting derating of the abnormal genset as long as the total power of the plant power is at or above the set point. There may be an action of replacing dispatch of power from the abnormal genset with dispatch of power from a normal genset when the total power of the plant power is below the set point.

The abnormality may be understood as previously disclosed.

In an embodiment of the method the actions of determining a number of gensets re- quired to cover the set point and dispatching power are functionally determined and/or selected from functions. A function may be based on a look-up table or database function. A function may be based on a selection of an output of a model. A function may be based on an output of an algorithmic model. There may also be a manual interface configure for operator input.

In an embodiment of the method the actions of determining a number of gensets required to cover the set point and dispatching power are functionally determined.

A function may be based on an input of a temperature of or in a genset. A function may be based on an input of fuel consumption of a genset. A function may be based on an input of grid frequency. A function may be based on an input of a grid voltage.

Implementation of such functions will result in a working device. It is noted that a person skilled in the may choose from different off the shelf technologies when implementing the functions. In an embodiment the method may further comprise actions of storing and processing an operating characteristic of an alternator of a generator of a genset and operating the genset within the limits of the operating characteristic. Thereby the generator is enabled to remain connected to the grid and to at least contribute to the stability of the net in an adaptive way. Thus, the generator may be operated to its full potential rather than be operated at fixed or limited operational point determined by the grid or grid codes. According to an aspect, the method may further comprise acts of updating the operating characteristic of the alternator of the generator.

The act of updating may comprise one or more acts of modelling and/or forecasting the operating characteristic of the alternator of the generator as a function of sensed operational conditions.

A person skilled in the art will appreciate the equivalences of the systems and methods disclosed herein. Example:

Normally a power plant will be given a set point as required from the customer. The required set point does not always demand full production from the gensets which means the gensets will not operate at the full limits, which limits may be determined load heat rate. The fuel consumption will equal the production, but the number of run- ning hours will be excessive compared to the production. A dispatch as disclosed may improve this as described by an example.

For a normal dispatch: power plant set point = 20 MW and genset power = 1400 kW the following applies:

• Number of gensets to run: 20*1000/1400 = 14.28 gensets -> 15 genset.

• Gensets load will be: 20000/(15* 1400)*100=95.24 %

• Run hours per day: 15*24=360h

• Production per day: 360* 1.400*0.9524=480 MWh • Production per run hour: 480/24= 20 MWh

For a dispatch as disclosed or an optimal dispatch, the gensets will drive up to the maximum dispatch and the following applies:

• Number of gensets to run: 20*1000/1400 =14.28 gensets -> 15 genset.

• Gensets load will be: (15* 1400)/(15*1400)*100= 100 %

• Run hours per day: 15*24=360h

• Production per day: 360* 1.400=504 MWh

· Production per run hour: 504/24=21 MWh

For the same production, the fuel consumption data can be assessed as follows:

• Fuel consumption @1333 kW: 333.51/h

21MWh requires : 21/1333 = 15.79 gensets

Consumption per hour : 15.79*333.5 = 5266 liter

• Fuel consumption @1400 kW: 350.2 1/h Consumption per hour: 15*350.2 = 5253 liter

Since the consumption and production in the 1.333 kW machine is less than maximum it is seen that more power can be produced in the same running time.

Then the owner of the power plant can sell more power for the same amount of running hours and the customer can receive more power in the same timeframe. Or if the fuel consumption does not match the number of running hours the owner can be pe- nalised.

It is noted that within the system, a derate caused by any abnormality may be accepted. If a generator for instance derates caused by overheating then the plant continues dispatching power with the present machines as long as the production is larger than the set point. If the derate function causes the plant output to decrease below the requested set point the priority of the faulty machine will be rearranged or swapped with a normal i.e. good machine and the plant commences operation as before the fault. Description of the Drawings

The invention is described by example only and with reference to the drawings, whereon: Fig. 1 illustrates generator controller and a power plant with a genset configuration in connection with a grid;

Fig. 2 illustrates a characteristic curve of an alternator of a generator of a genset; Fig. 3 illustrates a power plant with multiple gensets each with their generator controller embedded; illustrates a method of dispatching power from a power plant; Fig. 5 illustrates a method further comprising actions of detecting derating and accepting derating of a power module;

Fig. 6 illustrates a method where dispatching power is functionally determined and selected from one or more functions; and

Fig. 7 illustrates a method further comprising actions of operating the power module within the limits of operating characteristics.

In the following text the figures will be described one by one and the different parts and positions seen in the figures will be numbered with the same numbers in the different figures. Not all parts and positions indicated in a specific figure will necessarily be discussed together with that figure.

Detailed Description of the Invention

Item no Item

10 Generator controller

20 Power plant

22 Total power

24 Set point 30 Genset

32 Maximum rated limit

34 Number of gensets

36 Abnormality in genset

38 Abnormal genset

40 Grid

42 Load

50 Generator

52 Alternator

60 Operating characteristic

62 Capability curve

64 Limits

100 Method

110 Determining the set point

120 Determining the number gensets

130 Dispatching power

140 Detecting derating

150 Accepting derating

160 Replacing

210 Functions or manual

220 Functions of input paramters

Fig. 1 illustrates generator controller 10 configured to control power plant 20 to deliver total power 22 at a set point 24. The power plant 20 comprises more than one genset 30 or power module. There may be a number of gensets from genset 30i to genset 30n. Each genset 30i may deliver power at a maximum rated limit 32. The total power 22 may be dispatched to a grid 40 with a load 42.

Each genset 30 will have an engine or other power source50 with an alternator/generator 52 and the generator controller 10 may be configured to control the en- gine 50 or the alternator/generator 52. The generator controller 10 may be adapted to communicate and receive operational input from the genset 30. The generator controller 10 may further be configured to communicate and receive operational input from external systems such as the grid 40. The generator controller 10 may further be configured with communication means to transmit control signals to the power plant 20, the genset 30, the engine 50 and/or the alternator/generator 52. The generator controller 30 may be configured with a processor to process the input and further be configured with a storage to store input or processed input. The processor may be a computer or a similar unit for performing control logic.

In particular the generator controller 10 is configured to determine the number of gen- sets 34 required to cover the set point 24. Furthermore, the generator controller 10 may be configured to control the determined number 34 of gensets 34 from genset 30, genset 30i to genset 30n to dispatch power each at their maximum rated limitation 32.

Fig. 2 illustrates an engine 50 with an alternator 52 having a corresponding operating characteristic 60 characterised by a characteristic curve or a capability curve 62. Each genset 30 from fig. 1 may have an operating characteristic 60 and a capability curve 62. The controller 10 is configured to be able to store and process such operating characteristic 60 for each generator 50 in the power plant 20. Fig. 3 illustrates a power plant 20 with multiple gensets 30, 30i, ... 30n, each with their generator controller 10, lOi, ... 10η embedded within the genset 30. Each generator controller 1 Oi may be configured to control the power plant 20 and thus be able to control any other genset 30. Each generator controller 10, lOi, ... 10η may be configured to communicate and control each and every of the gensets 30, 30i, ... 30n in the power plant 20. In particular each controller may server as a data storage and data processing unit for each genset 30i whilst there is a selected or chosen master controller amongst the generator controllers 10, lOi, ... 10η.

Fig. 4 illustrates a method 100 of dispatching power from a power plant 20. The power plant 20, the genset 30 and the generator controller 10 may be as previously disclosed. Thus the following description is understood in view of the previous figures. At the same time the following description discloses features of the generator controller 10.

In particular the method 100 of dispatching power from a power plant 20 with more than one genset 30 each configured to dispatch power up to a rated maximum limit 32 and the power plant 20 to dispatch a total power 22 at or above a set point 24 to cover a given load 42 on a grid 40. The method 100 may comprise the following actions.

There may be an action of determining 110 the set point 24.

There may be an action of determining 120 the number gensets (34) required to cover the set point 24.

There may be an action of dispatching 130 power from the determined number of gen- sets 34 each operating at their maximum rated limitation 32.

Fig. 5 illustrates a method further comprising actions of detecting derating and accepting derating of a power module. With reference to figure 4, the method 100 of dispatching power from a power plant 20, there may be additional actions.

There may be an action of detecting derating 140 of a genset 30 caused by an abnormality 36.

There may be an action of accepting derating 150 of the abnormal genset 38 as long as the total power 22 of the plant power 20 is at or above the set point 24.

There may be an action of replacing 160 dispatch of power from the abnormal genset 36 with dispatch of power from a normal genset 36 when the total power 22 of the plant power 20 is below the set point 24.

Fig. 6 illustrates the method 100 of dispatching power disclosed in figure 4 or 5 and where the actions of determining a number of gensets 34 required to cover the set point 24 and dispatching power are functionally determined. The functions 210 used may be selected or implemented from one or more of the following functions or selection methods.

The action of determining the number of gensets 34 may implemented by simple arithmetic.

The method 100 may use a function based on a look-up table or database function to operate. The method 100 may use a function based on a selection of an output of a model. Thus a model may predict or output one or more results amongst which a selection is performed.

The method 100 may use a function based on an output of an algorithmic model. Thus a model may be automatic. The algorithmic model may be programmed in computational unit and be based on logic and mathematical models of the genset.

The method 100 may involve actions from an operator via a manual interface configured for operator input.

Figure 6 also illustrates the method 100 of dispatching power disclosed in figure 4 or 5 and where the actions of determining a number of gensets 34 required to cover the set point 24 and dispatching power are functionally determined. The functions 220 used may be selected or implemented from one or more of the following functions or selection methods.

There may be a function based on an input of a temperature of or in a genset 30. There may be a function based on an input of fuel consumption of a genset 30. There may be a function of a grid frequency. There may be a function based on input of a grid volt- age. For each of the parameter inputs there may be provided means for providing the measurement and the required processing or pre-processing that represent the input.

Fig. 7 illustrates a method further comprising actions of operating the power module within the limits of operating characteristics. The method 100 of dispatching power from a power plant 20 may comprise actions that involve storing and processing 170 an operating characteristic 60 of an alternator 52 of a generator 50 of a genset 30. The method 100 may further include operating 180 the genset 30 within the limits 64 of the operating characteristic 60.

The actions of storing and processing 170 and operating 180 the genset 30 within the limits 64 of the operating characteristic 60 may take place separately from the implementation of the controller i.e. be performed by or in each individual genset.

Claims

1. A generator controller (10) configured to control a dispatch of power from a power plant (20) with more than one genset (30), each genset (30) configured to dispatch power up to a rated maximum limit (32) and the power plant (20) to dispatch a total power (22) at or above a set point (24) to cover a given load (42) of a grid (40), wherein the controller (10) is configured to determine a number of gensets (34) required to cover the set point (24) and to control the determined number of gensets (34) to dispatch power each at their maximum rated limitation (32).

2. A generator controller (10) according to claim 1 and further configured to accept a derating of a genset (30) caused by an abnormality in the genset (36) and configured to maintain the determined number of gensets (34) to dispatch power until the total power plant power (22) is below the set point (24) before determining a new number of gensets (34') each to dispatch power each at their maximum rated limitation (32).

3. A generator controller (10) according to claim 1 or 2 and configured to store and process an operating characteristic (60) of an alternator (52) of a generator (50) of the genset (30) and configured to operate the genset (30) within the limits (64) of the op- erating characteristic (60).

4. A generator controller (10) according to any of claim 1 to 3, wherein the generator controller (10) is configured to be embedded in one or more genset (30).

5. A power plant (20) with more than one genset (30) and with a controller (10) according to any one of claims 1 to 4.

6. A method (100) of dispatching power from a power plant (20) with more than one genset (30), each configured to dispatch power up to a rated maximum limit (32) and the power plant (20) to dispatch a total power (22) at or above a set point (24) to cover a given load (42) on a grid (40), the method comprising actions of:

- determining (110) the set point (24);

- determining (120) the number gensets (34) required to cover set point (24); - dispatching (130) power from the determined number of gensets (34) each operating at their maximum rated limitation (32).

7. A method (100) of dispatching power from a power plant (20) according to claim 6, further comprising actions of:

- detecting derating (140) of a genset (30) caused by an abnormality (36);

- accepting derating (150) of the abnormal genset (38) as long as the total power (22) of the plant power (20) is at or above the set point (24); or

- replacing (160) dispatch of power from the abnormal genset (36) with dispatch of power from a normal genset (36) when the total power (22) of the plant power (20) is below the set point (24).

8. A method (100) of dispatching power from a power plant (20) according to claim 6 or 7, wherein the actions of determining a number of gensets (34) required to cover the set point (24) and dispatching power are functionally (210) determined and selected from one or more of a group of:

- a function based on a look-up table or database function;

- a function based on a selection of an output of a model;

- a function based on an output of an algorithmic model; and/or

- a manual interface configure for operator input.

9. A method (100) of dispatching power from a power plant (20) according to any of claims 6 to 8 wherein the actions of determining a number of gensets (34) required to cover the set point (24) and dispatching power are functionally (220) determined and selected from a group of:

- a function of a temperature of or in a genset (30);

- a function of fuel consumption of a genset (30);

- a function of grid frequency; or

- a function based on input of a grid voltage.

10. A method (100) of dispatching power from a power plant (20) according to any of claim 6 to 9, comprising actions of:

- storing and processing (170) an operating characteristic (60) of an alternator (52) of a generator (50) of a genset (30); and - operating (180) the genset (30) within the limits (64) of the operating characteristic (60).