The present invention relates to an emergency power system for ful filling a power requirement in case of a sudden di f ferential power requirement state , such as in the event of power failure or power shortage by a supply of electrical energy to power supply of a building or facility . Furthermore , the present invention relates to a related method .

It is known to provide a building with a backup power supply for electric power . Such backup power supply comprises a generator with an engine for driving the generator . It is a disadvantage of such systems that either the system is running on standby, which causes where the system and during which fuel is burned . In case the system is fully shut of f , it takes a long time to provide stable power to all power consumers in the building because it takes time for the engine to start up and it takes time for the generator to provide the stable power after the engine has started up .

In order to obviate such disadvantage , and to improve upon the prior art , the present invention provides an emergency power system for ful filling a power requirement in case of a sudden di f ferential power requirement state , such as in the event of power failure or power shortage by a supply of electrical energy to power supply of a building or facility, the system comprising :

- at least one power supply line connected to a grid for distributing electrical energy between a power supply and power consumers in the building,

- at least one power supply line monitoring device for monitoring power parameters of the power supply line ,

- at least one genset for the generation of the electrical energy to the at least one power supply line , a gen- set comprising a power station or an engine and a generator for generating electricity,

- at least one genset controller for controlling operation of the at least one genset , wherein :

- at least one of the at least one genset is configured to function in a power generating mode for the generation of the electrical energy,

- at least one of the at least one genset is configured for functioning in a standby operation mode , wherein the power station or engine may be switched of f or operate in a low-power, such as low load mode of operation, and

- at least one of the at least one the genset controller is configured to receive an input signal signi fying the sudden di f ferential energy requirement state , to make a determination to trans fer a respective genset from the standby operation mode to the power generating mode and to control respective gensets functioning in the standby operation mode to transition operation to ful fill the power requirement , and wherein :

- during the standby operation mode of the genset , the generator of the genset is configured to operate in a state of synchroni zation with the power supply line , preferably powered with power from the power supply line .

It is an advantage of the system according to the present invention that because the generator of the genset is configured to operate in a state of synchroni zation with the power supply line , only the engine of the genset needs to start up while the power parameters that are delivered by the generator are merely slightly af fected . In case a sudden di f ferential energy requirement state arises , the respective genset may be trans ferred to its power generating mode in a very short timeframe based on the receiving the input signal . The input signal may be based on a low frequency and/or voltage of the power line has a powerline parameter . However, alternatively, in case of failure of an already running genset that is operating in power generating mode while the other genset is in the standby operating mode , a signal from the genset functioning in power generating mode indicating problems , imminent failure or upcoming failure , may be provided to the genset controller in order to trans ferred the genset in the standby operating mode to the power generating mode even before main power line parameters are af fected by such failure of the other genset .

In case a relevant number of such systems are available and/or operating in an area, the generator is running in synchronicity with the grid may provide a positive contribution to stability of the grid, such as by means of providing reactive power . In for instance a hospital , such generator running in synchronicity with the main power lines of the hospital , is able to absorb reactive power instances arising from switching of appliances in the hospital . Otherwise , it is able to absorb reactive power instances that are incoming to the hospital power grid from the external power grid the hospital is obtaining its power from .

Alternatively, when a grid indicates a low-power situation in an area in which at least one of these systems are available , the grid may provide a signal to at least one of such systems to power its building or even provide power to the grid to alleviate such issue .

According to a first preferred embodiment , the system provides timely power activation by the at least one genset configured for functioning in the standby operation mode . It is an advantage of such embodiment that the building may be provided with power on the basis of this provided power in such a fast manner, such as in time frames indicated below, that the building is provided with power in timely manner to prevent a calamity, such as damages by power loss in power consumers in the building .

According to a further preferred embodiment , the sudden di f ferential power requirement state is defined as a state wherein a di f ference between a currently supplied electrical power and a required power supply is larger than the amount of power that can be provided by gensets that are currently in the power generating mode . When a large consumer is started up or when a current consumer is put under a heavy load, and the grid power, or an already running genset , was not capable of providing to such rise in power requirement , the at least one genset configured to function in standby operation mode and running in standby operation mode is able to quickly add power capacity to the other running gensets . Thereby it is advantageously achieved that the power requirement is met during rise of the power demand by such influence of the rising power demand .

In an alternative manner, the sudden di f ferential power requirement state is defined as a state wherein power supply line parameters are outside predefined operational or operationally acceptable ranges . When this happens , such as when a voltage rises or lowers beyond operationally acceptable parameters or when a frequency that normally would be maintained at substantially 50 Hz drops below such acceptable ranges , such as for example 47 Hz but any value may be used, a quick rise in supply will power is required and may prevent a blackout of the system as a whole .

In a further alternative manner, the sudden di f ferential power requirement state is defined as a blackout situation of at least one of the at least one power supply line . A blackout situation may happen when a single running genset fai ls or when power demand suddenly exceeds the available genset power . Other situations in which a blackout situation may happen can be caused by a short-circuit or failing of a power consumer connected to any of the at least one power supply line . When that happens , it is vitally important that all af fected systems are disconnected from the respective power supply line and the system is powered up as soon as possible . The use of a genset configured to run at standby operating mode is provided according to the embodiment to provide the fastest possible restart of the electrical system of the bui lding as a whole . In case of a blackout , it is important that essential systems are connected again first and optional systems are only connected when safety is provided .

In a further alternative manner, the sudden di f ferential power requirement state is defined as a power requirement input based on a sudden power requirement caused by a power consumer of the building . It may happen that an unexpected change or rise in power usage in the building has to be provided at a moments notice . I f this happens , the power demand may be rising very steeply which may not be providable by a for instance single running genset . When this happens , a system according to the embodiment provides that a genset configured for functioning in a standby operating mode may be switched to its power generating mode very quickly to provide power within a speci fied acceptable time . An example thereof is that a building that is using little power may start using high power, even when it was running on one relatively small genset while a relatively large genset configured for functioning in a standby operating mode actually was in such standby operating mode according to the present invention or an embodiment thereof to provide switching to power generating mode in an acceptable small timeframe .

According to a further preferred embodiment , the fulfilling of the power requirement is time-critical within a time frame of the 0-20 seconds , preferably 0- 15 seconds , further preferably 0- 10 seconds , further preferably 1 - 8 seconds , further preferably 1 - 6 seconds , further preferably 1-5, 1 -4 , 1 -3 , 1 -2 seconds . It is an advantage of such implementation of time critical results , that it may be achieved that a building equipped to such an embodiment may be considered to be a safe system while saving the fuel by allowing at least one of the gensets to be configured for standby operating mode .

According to a further preferred embodiment , wherein ful filling of the power requirement is based on a power requirement . Such power requirement is related to the amount of power that is required to have the building' s electrical system and connected devices function .

A further preferred embodiment of the present invention provides a system comprising a data store for storing power requirements in relation to building control parameters , power parameters of the at least one genset , power parameters of the at least one genset configured for functioning in standby operating mode . With such predetermined and prestored data, all kinds of combinations of power that may be provided by a respective genset or combination of gensets and power requirements by such conditions may be combined for a suitable outcome . In case a building goes from a relatively low power usage to a situation with high- power usage , a relatively light capacity genset may be switched of f in favor of a relatively high capacity genset , of course preferably both with the configuration to function in standby power mode . Further preferably, the system comprises at least one breaker , preferably at least one breaker per genset drive motor and/or further power supply line consumer . With the application of such breakers , all systems may be switched of f from the main power line during powering on of a genset from a sudden di f ferential power requirement state . This allows for controlled powering on of the main power line connected systems or keeping certain subsystems of the building system disconnected from the main power line by not unbreaking or closing the breakers .

Further preferably, in the standby operating mode , the engine may be operated below 30% of nominal capacity, preferably below 20% of nominal capacity, further preferably below 10% of nominal capacity, further preferably below 0% of nominal capacity, further preferably below minus 5% of normal capacity further preferably between minus 5% and minus 10% of nominal capacity . This allows for favorable fuel savings during standby operating mode , while keeping the engine in motion for faster start up then when the engine was stopped . It is furthermore provided that the engine is dragged along by the generator based on for instance main power line electrical power .

According to a further preferred embodiment , the system comprises a clutch between the power station or engine and the generator, the genset being configured to allow the coupling by the clutch in the standby operating mode . With such clutch, it is provided in an advantageous manner that the engine may be fully stopped for motion while the generator is kept in rotation to be synchroni zed with the main power line .

In a further preferred embodiment , the system compraises a flywheel wherein the flywheel is preferably coupled to the generator, preferably further comprising decou- pling means for decoupling of the flywheel from the generator . It is an advantage of such a flywheel that even without main power line power the generator may be kept in rotation for a predetermined amount of time based on energy stored in the flywheel . For instance , in case of a full blackout of the electrical systems of the building, a startup of the genset that was in standby operating mode may be performed faster with the application of this flywheel .

According to a further preferred embodiment , the system comprises a heater as on Memorial the planes of sembly for heating of the engine while being switched of f or in low load mode . With this , the engine is easier to start up and will endure less wear and tear during standby operating mode , and/or during times of low fuel supply while being kept in rotation by the generator as indicated in the above .

According to a further preferred embodiment , the system comprises venting means for venting of engine cylinders when the engine is operating at low rotations per minutes . An advantage thereof is that it requires less power to run the engine while little fuel is provided to the engine . Alternatively, the system comprises a pressuri zing assembly for pressuri zing engine cylinders to a preferred state and/or to prevent low pressure in the cylinders .

According to a further preferred embodiment , the system comprises a system controller to adj ust power take-up to a power level providable by currently available genset capacity . In case a genset is started up from standby operation mode to power generating mode while not being able to sustain full power demand of the electrical system of the building and connected devices , only systems in the building that are essential and ful fill the power requirements of the available power from such genset will be started up .

A further aspect of the present invention relates to a method for ful filling a power requirement in case of a sudden di f ferential power requirement state , such as in the event of power failure or power shortage by a supply of electrical energy to power supply of a building or facility, the system comprising :

- at least one power supply line connected to a grid for distributing electrical energy between a power supply and power consumers in the building,

- at least one power supply line monitoring device for monitoring power parameters of the power supply line ,

- at least one genset for the generation of the electrical energy to the at least one power supply line , a genset comprising a power station or an engine and a generator for generating electricity,

- at least one genset controller for controlling operation of the at least one genset , wherein :

- at least one of the at least one genset is configured to function in a power generating mode for the generation of the electrical energy,

- at least one of the at least one genset is configured for functioning in a standby operation mode , such as wherein the power station or engine may be switched of f or operate in a low-power, such as low load mode of operation, and

- at least one of the at least one the genset controller is configured to receive an input signal signi fying the sudden di f ferential energy requirement state , to make a determination to trans fer a respective genset from the standby operation mode to the power generating mode and to control respective gensets functioning in the standby operation mode to transition operation to ful fill the power re- quirement , the method comprising steps of :

- monitoring the power supply line by the power supply line monitoring device ,

- operating at least one of the at least one genset in the power generating mode according to current power requirements ,

- monitoring for an input signal by the at least one genset controller,

- upon receipt of an input signal signi fying the sudden di f ferential energy requirement state , such as from the power supply line monitoring device , trans ferring a respective genset from the standby operating mode to the power generating mode and control the at least one genset to transition operation to ful fill the power requirement . Such method provides advantages as indicated in the above in relation to the first aspect of the present invention . Furthermore , respective method steps are provided for application of each feature of the above aspect .

Further advantages , features and details of the present invention will be further elucidated on the basis of a description of one or more preferred embodiments with reference to the accompanying figures . Similar yet not necessarily identical parts of di f ferent preferred embodiments may be indicated with the same reference numerals .

Fig . 1 provides a schematic representation of a first preferred embodiment according to the present invention .

Fig . 2 provides a schematic representation of a further preferred embodiment according to the present invention .

Fig . 3 provides a further schematic representation of a further preferred embodiment according to the present invention .

A first preferred embodiment ( Fig . 1 ) according to the present invention relates to a power system, such as usable in a building or facility . It comprises two gensets 2 that are controlled by a genset controller 17 that is embodied as a process on a control computer 7 . In an alternative embodiment , the genset controller 17 may be embodied as a separate control computer . The gensets each comprise a generator 8 that is provided with motion energy by a motor 6. The generator is provided with an optional flywheel 15 to store motion energy during operation of the genset . The flywheel 15 is optional as the system according to the present invention or certain preferred embodiments , is capable to function without a flywheel . Furthermore , the genset is provided with a clutch or clutching assembly 12 for coupling and decoupling the generator 8 from the engine 6 . Such decoupling is provided in a preferable standby operation mode .

During the standby operation mode , it is preferred that the engine 6 is switched of f in order to prevent use of fuel . In case the engine is switched of f , it is preferred according to a preferred embodiment , that the motor is heated from an external heating system in order to be maintained at a temperature at or somewhat below operating temperature of the engine or a cooling system thereof . This may provide a faster start time of the engine when the engine needs to be started to trans ferred the system from the standby operating mode to the power generating mode . It is preferred that the engine is maintained at any temperature between ambient temperature and operating temperature in order to achieve an improvement over maintaining the engine at ambient temperature .

Alternatively to switching of f of the engine , it is preferred to the engine 6 is running at a low load such as below 30% of nominal capacity in order to save fuel . During such low load operation of the engine 6 , less fuel is provided then required to operate the engine at or above 30% of nominal capacity . During such operation, the motor may be coupled with the generator in order to be driven or forced into motion by the generator . When the generator is driving the engine , less fuel is required to run the engine . Also during low load operation of the engine , the engine may be heated from an external heat source to raise temperature above the temperature achieved by the low fuel input .

In the embodiment of Fig . 1 , both generator sets are configured to be able to run in both a power generating mode and a standby operating mode . According to the present invention, also an embodiment in which only one of the two generator sets is configured to also run in the standby operating mode is considered . With the embodiment of Fig . 1 , both gensets may be used for providing power with the other one on standby . In case only 1 of the 2 generator sets is configured to also run in the standby operating mode , it is required that the thus configured generator set is to be the one that may be on standby while the other generator set that can only run in power generating mode is to be continuously operated for providing power to the building .

A genset is configured for functioning in a standby operating mode , when the genset controller is able to control the use of fuel below 30% of nominal capacity, to control a clutch to decouple the generator 8 from the engine 6, to control the generator to operate in a state of synchroni zation with the main power line and/or to control that the generator is provided with power, preferably from the main power line , to operate in the state of synchronization with the main power line . The power for operating of the generator in synchroni zation with the main power line may also be provided in an alternative manner , such as by means of an auxiliary engine with drive means coupled to the generator .

A main power line 3 is provided between the generators and power consumers 16 , 16 ' , 16" such as of a building . Alternatively, not shown, the main power line provides energy to all electric systems of a building . Several main power lines may be provided throughout the building separated by power converters . In that way, distinct systems of the building to be provided with electric energy with distinct power parameters or respective main power line parameters . Operation of the electricity consumers 16 of the building may be performed by a power controller that is a distinct control computer or such as in the embodiment of Fig . 1 embodied as a process performed by and/or controlled by the computer 7 .

In Fig . 2 , a variant is shown in which only the genset that is configured for functioning in a standby operating mode is shown while another genset that may only operate in power generating mode is omitted for simplicity . The main power line 3 connects the genset or gensets with the power consumers 16 , 16 ' . The central control computer 7 is provided to control overall operation of the building thereby controlling the respective controllers 14 . The system also comprises a main power line monitoring device 28 that monitors power parameters of the main power line and provides information of the power parameters to any computer 7 or controller 14 on the building . The information monitoring may be performed continuously or only in case of a deviation from desired parameter values such as beyond a predetermined threshold of any parameter . In case the voltage drops below a certain value , this may mean that additional power is to be supplied to the main power line ac- cording to the present invention by switching a genset that is configured for functioning in a standby operation mode and that is operating in such standby operating mode , to a power generating mode . Another example of a main power line parameter value is the frequency of the AC current on the main power line . In case of frequency drops below a predetermined threshold, such as below 47 Hz when 50 Hz is the operating frequency, a standby genset may be started up .

It is preferred that systems or subsystems , such as the generator set , a heater thereof , a power consumer or any other electric system of the building is connected to the main power line or at least one main power line by means of a breaker 22 , 24 , 26 or 26 ' . The advantage or purpose thereof is that such devices or subsystems of the building may be protected in case of a set electrical emergency and/or such that such devices of subsystems may be kept switched of f from the main power line in case of available power to the main power line is too low or limited to provide all subsystems with energy .

Alternative considerations for the amount of power a genset that is to operate as a genset configured for functioning in a standby mode , is to be able to provide suf ficient power for a power demand of subsystems of the building that are deemed important or that are currently used for and operating function of the building . An example thereof is a building with a cooling system is required to have power provided to the cooling system .

An example of states and steps to be performed in or by a system according to the present invention or in embodiments thereof is as follows . During regular operation of the building, a part of the available generator sets is providing power to systems of the building . In a situation, that may be named a blackout , the main power line is to be started up again and/or provided with power . In this case , preferably all breakers are disconnected, the genset that is configured for functioning in a standby operation mode and that is functioning in the standby operation mode is provided with a signal to switch to power generating mode .

In such situation, the generator 8 of the genset is already rotating at main power line parameters , such as frequency . This means that the generator does not have to be start-ed up from a standstill provide power to the busbar, but only the engine needs to be started up to continued the motion of the generator . Starting up of the engine requires little time , especially when the engine is kept in operating condition, such as having a suitable temperature , or already being in motion running at low load with low fuel , such as being drawn by the generator or kept into motion by a secondary engine . Thus , advantageously, the engine 6 of the genset is started up from the standby condition and coupled with the generator and the generator is starting to provide power to the main power line for the purpose of which the breaker is closed to provide the power to the main power line . With this , the operation of the engine 6 and the generator 8 are closely monitored by the controller 14 in order to provide power to the main power line with right parameters relating to frequency and voltage .

The engine running at low capacity may comprise running on low fuel . The engine running at negative ca-pacity is preferably intended to mean that the engine is pulled by the generator coupled to the engine , prefera-bly wherein the generator is provided with energy from the at least one power supply line .

The present invention is described in the foregoing on the basis of preferred embodiments . Di f ferent aspects of di f ferent embodiments are expressly considered disclosed in combination with each other and in all combinations that on the basis of this document , when read by a skilled person of the area of skill , fall within the scope of the inven- tion or are deemed to be read with the disclosure of this document . These preferred embodiments are not limitative for the scope of protection of this document . The rights sought are defined in the appended claims .