WO2011077393A2

WO2011077393A2 - Improvements to electrical systems with auxiliary generating means

Info

Publication number: WO2011077393A2
Application number: PCT/IB2010/056021
Authority: WO
Inventors: Luigi Gozzi
Original assignee: Pramac S.P.A.
Priority date: 2009-12-23
Filing date: 2010-12-22
Publication date: 2011-06-30
Also published as: ITTO20091032A1; WO2011077393A3

Abstract

An electrical system (P) intended to be connected to an electrical power distribution network (GRID) through respective connection means (MU) for supplying user circuits and apparatus (L) in a normal operation condition, comprising an automatic failure control unit (CUM) which is adapted to detect availability of electrical power from the distribution network (GRID), having a control signal output (CTRL) connected to the network of power conductors downstream of the connection means (MU), and which is designed to transmit a control signal (SPLC) to an auxiliary generator set (G) previously associated with the system (P), as a powerline communication signal conveyed on the power conductors of the network towards the socket connector (S) to which the generator set (G) is plugged-in.

Description

Improvements to electrical systems with auxiliary generating means

The present invention relates to electrical systems, and more specifically to an electrical system intended to be connected to an electrical power distribution network through respective connection means for supplying user circuits and apparatus in a normal operation condition, and comprising:

a network of power conductors equipped with load connection means for the connection of said user apparatus; and

an automatic failure control unit, adapted to detect availability of electrical power from the distribution network and arranged for emitting a control signal to auxiliary generating means which may be previously associated with the system, in case of interruption of the power supply from said network.

In this description, the term "electrical system" denotes an electrical system suitable for connection systems with plug and socket outlets for power transmission up to a maximum of 50 kW, for example an electrical system intended for civil use, such as a domestic system for serving a single building or a limited group of buildings within a single residential complex, or an electrical system for industrial uses requiring limited power. Figure 1 shows an electrical power supply system for civil buildings including an arrangement of an electrical system according to the prior art and an associated generator set.

Between the delivery point of the electrical power supplied by a public distribution network generally indicated GRID, where a conventional energy meter MU is installed, and the network of power conductors of the circuits of the local system P, provided with a plurality of plug and socket outlets S for the connection of the user apparatus (or loads) L, there is an automatic mains failure module AMF, adapted to switch the power supply to the system between the public distribution network, in a normal operation condition, and an emergency or reserve generator set G associated beforehand with the system, in case of a temporary interruption of the supply of power from the network. The automatic mains failure module AMF comprises an electronic control unit CU installed downstream of the energy meter, designed for the simultaneous control of two contactor devices SI, S2 adapted to establish and break, alternatively, the continuity of a main supply line MAINS running from the point of delivery of power from the public network and that of an auxiliary supply line AUX running from the emergency generator set.

The emergency generator set, which is typically a set with a power rating of less than 50 kVA, is installed permanently by means of a fixed connection and is located in a room of the building, such as a basement or similar environment, which has been prepared in accordance with the safety regulations concerning the ventilation of rooms, heat dissipation, resupply of fuel and soundproofing, and other less important matters.

The generator set G is connected to the automatic failure control module AMF by installing power transmission cables LI and an associated signal line L2 which can convey control signals for activation or de-activation of the generator set, these signals being generated in the automatic failure control module AMF, and monitoring signals relating to the operating conditions of the generating set, such as the operating temperature, the fuel reserve, and the like.

Since the generator set is not usually installed in the room containing the energy meter associated with the automatic failure control module, the conversion of a conventional residential system to a system with auxiliary (emergency or reserve) generator means requires work to be carried out on the walls of the building for the installation of the cables for connection to the generator set, at considerable cost and inconvenience.

Finally, the overall dimensions of the automatic failure control module are considerable, since a wall housing measuring approximately 50 x 50 x 20 cm, for example, is required, with the main and auxiliary power supply lines running into it, this housing enclosing the corresponding contactor devices and the associated control unit. US 2003/0034693 Al describes a power supply system for buildings, of the type shown in Figure 1. The auxiliary generator is connected to a switching unit interposed between the power distribution network and the electrical system of the building downstream of the meter. The switching unit is designed to detect the power supply voltage of the distribution network and to activate the auxiliary generator in case of a power cut. The switching unit also has a remote communication function with a user-accessible interface unit, using powerline communication technology on the existing building wiring, for the display of information on the state of supply of the electrical system of the building. The object of the present invention is to provide a satisfactory solution to the problem that has been presented, and more particularly to propose an electrical system configuration adapted to facilitate integration with auxiliary emergency or reserve generator means while avoiding the drawbacks of the prior art.

Another object of the invention is to provide an integrated power supply system for residential or industrial users, including an auxiliary generator set for supplying an electrical system in case of interruption in the power supply from the public distribution network, wherein the generator set is easily removable for temporary use in another location.

According to the present invention, these objects are achieved by means of an electrical system characterized in that the automatic failure control unit has a control signal output connected to the network of power conductors downstream of the connection means, and is arranged for transmitting said control signal as a powerline communication signal on the power conductors of the network towards at least one of the load connection means available for connection to the auxiliary generating means.

Specific embodiments are described in the dependent claims, the content of which is to be considered as an integral or integrating part of the present description.

The invention also proposes a generator set and an integrated power supply system as claimed. Briefly, the present invention is based on the principle of using the power conductor network of the electrical system as the vehicle for the transmission of the control signals for the generator set associated with the system, the connection of the generator set to the system network being made through an ordinary plug and socket outlet typically provided for the connection of user apparatus.

Advantageously, this configuration does not require the installation of further electrical connections in addition to those already available, and therefore does not require work on the wall structures of buildings to provide access to a room where the generator set is located, while it also provides the same functionality with a smaller number of devices (one contactor device only) and therefore enables the overall dimensions of the automatic failure control module to be kept smaller.

A further advantage of the invention is that the generator set is installed using a removable connection, such as an ordinary plug and socket outlet, and therefore the generator set can be temporarily disconnected and used as a conventional generator set which is transportable to another location.

Further characteristics and advantages of the invention will be disclosed more fully in the following detailed description of one embodiment of the invention, provided by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 is a schematic representation of a power supply system comprising an electrical system and associated auxiliary generator means according to the prior art, as described above; and

Figure 2 is a schematic representation of a power supply system based on an electrical system arrangement according to the invention.

In Figure 2, elements or components which are identical or functionally equivalent to those shown in Figure 1 have been indicated by the same references as those used in the description of the preceding figure.

A public distribution network GRID supplies power to a system P, for example a residential system, which is connected to it at a delivery point where an energy meter MU is installed. Downstream of the energy meter, a main supply line MAINS is branched into a network of power conductors to make the network voltage available at a plurality of power outlets S and enable power to be supplied to the user apparatus L connected thereto.

In the main supply line MAINS, immediately downstream of the energy meter MU, there is an interposed contactor device SW designed to establish or break the connection to the distribution network, in other words the continuity of the main supply line. The contactor device SW is typically a contactor device which is open when at rest, that is to say its rest position is one in which the contacts are open, this device being kept in the operating position (with the contacts closed) by a corresponding energizing coil supplied from the same power network.

A main automatic failure control unit CU is installed in the proximity of the contactor device SW, and is connected to the terminals of the device in order to detect the operating voltage upstream and downstream of the aforesaid device, at respective detection points Dl and D2.

Downstream of the contactor device, at the point D2, the control unit has a control signal output CTRL connected to the power conductor network, designed to transmit at least one powerline communication control signal SPLC on the power conductors of the network towards at least one of said outlet connector means S.

Advantageously, in a preferred embodiment, the control signal SPLC is a simple binary signal, of the ON/OFF type, which is immediately recognizable by the receiving device to which it is sent. The method of modulation of the signal SPLC, its operating frequency, the data transmission rate and the communication protocol are chosen according to the teachings of the prior art, and will not be described in detail here, since they are not essential for the understanding of the invention.

An emergency or reserve generator set G, including an electrical generator and a corresponding thermal engine for driving it, can be associated with the system by connection to one of the connector outlets S, to supply power to the user apparatus connected to the power outlets in case of a temporary interruption of the power supply from the public distribution network GRID. Specifically, a generator set, which is typically adapted to supply power in the range from 0.5 to 50 kW, and which is preferably controllable to prevent the supply of a higher level of power than that which is permitted or can be withstood by the system (civil residential , systems are typically designed to withstand a single-phase voltage of 220 V and a current of 16 A, while industrial systems are typically designed to withstand a three-phase voltage of 400 V and a current of 63 A), is connected to a power outlet S of the system in the same way as an ordinary user apparatus, and is therefore disconnectable. It is connected to the power network of the system and to the main automatic failure control unit CUM through the power outlet to which it is connected, for the supply of power and for the transmission of signals respectively, the signals including the control signals for activating or de- activating the generator set, generated by the control unit CUM, or the state signals of the generator set, which are generated within the set itself. The generator set G comprises a corresponding control unit CUQ which can be interfaced with the power conductor network by means of the connection to the outlet S, this unit being adapted to establish a powerline communication signal connection to the main control unit of the system CUM in a master- slave configuration, in which it preferably operates exclusively as a slave unit. The control unit CUG is interfaced with the electrical system in order to receive the control signals regarding the operation of the generator set from the failure control unit CUM and also in order to draw directly from the system the power required to keep its supply battery and a starting battery of the generator set in working order.

By supplementing the local electrical system P with an auxiliary generator set G connected to a power outlet of the system, it is possible to create an integrated power supply system which can compensate for a temporary interruption in the power supply from the public distribution network by auxiliary generation of power using the generator set.

The operation of the integrated system described above is therefore as follows. In a normal operation condition, the automatic failure control unit CU_M detects the presence of a voltage at the detection point Dl upstream of the contactor device SW, which is kept in the closed position by the supply of power to the corresponding energizing coil through the electrical network.

If the power supply from the distribution network GRID is interrupted, the contact device SW opens automatically if no power is supplied to its energizing coil, and the control unit CUM does not detect the presence of a voltage at the detection point Dl and, consequently, emits at the output CTRL a powerline communication control signal SPLC on the power conductor network, including an instruction for activating the generator set G (if connected), sent to the corresponding control unit CUG-

Obviously, the failure control unit CUM is provided with its own buffer supply battery, which is kept constantly in a working condition, and which can compensate for the absence of a supply from the network during the operations of activating the generator set, although it cannot power the energizing coil of the contactor SW.

When the control unit CUG of the generator set G connected to the system receives a control signal SPLC including an activation instruction, it executes the procedure of activating the generator set. In a preferred embodiment, this procedure includes the transmission of the activation request signal to a further control module, typically provided in manual generators according to the prior art, designed to control the starting and stopping of the thermal engine and also to monitor the corresponding operating parameters such as the water temperature, the oil pressure and the fuel level.

Clearly, in this case the control signal SPLC travels over the network of power conductors of the system without any interference, since no power is being supplied to the network.

The control unit CU_M is then set to detect the establishment of the supply voltage upstream of the contactor device SW, which indicates that power is once again available from the public distribution network GRID. When this happens, the control unit CU_M emits from its output CTRL a carrier frequency control signal SPLC on the power conductor network towards the slave control unit CU_G, including an instruction to de-activate the generator set G, and is set to command the resetting of the contactor device SW after the de-activation of the generator set. The de-activation of the generator set is, for example, recognized by the acquisition of an operating state signal relating to the generator set, emitted by the slave control unit CUG, this signal also being conveyed as a carrier frequency signal on the power conductors of the network towards the main control unit CU_M of the system, preferably in response to interrogation by the latter.

Alternatively, or in combination with the above method in a redundant configuration, the de-activation of the generator set is recognized as a result of the detection of the absence of voltage at the detection point D2. The main control unit CUM does not emit a consent signal to reset the contactor device until it has ascertained the state of de-activation of the generator set, in order to avoid accidental parallel use of the public network GRID and the generator set G, which might damage the latter. It should be noted that, in a preferred embodiment, the control unit CUG of the generator set is also designed to prevent any sudden activation of the set if it detects the presence of a voltage on the local network which is not generated by the set itself.

Clearly, in this case the control signal SPLC travels on an active line, and is superimposed on the voltage established in the network circuits by the generator set. However, the powerline communication method provides a reliable means of communication without any appreciable deterioration of the information, because of the reduced length of the connections (of the order of a few metres or tens of metres) along which the signal passes.

In a more advantageous embodiment, in an integrated configuration for a home automation system, the main automatic failure control unit CUM can also emit control signals for user apparatus L connected to the system by a corresponding power connection to an outlet S.

In this case, the control unit CUM, in a condition of auxiliary power supply to the system, is designed to recognize the user apparatus requiring a power supply even in emergency conditions as distinct from those whose operation is not a priority, for example according to a predetermined order of priority among the user apparatus, and consequently to emit signals for selective (re-)activation or de-activation of the user apparatus connected to the system, as a function of the maximum power that can be supplied by the generator set.

Conveniently, an automatic failure control unit according to the invention can be integrated into an electrical connection device in a space corresponding to approximately 4-6 DIN modules, according to the European standard convention, and can therefore be easily installed in a distribution panel such as the main distribution panel of an apartment.

It should be noted that the embodiment of the present invention proposed in the preceding discussion is purely exemplary and does not limit the present invention. A person skilled in the art can easily apply the invention in different embodiments, which, however, do not depart from the principles set out above, and which therefore lie within the scope of protection defined by the attached claims.

Claims

1. Electrical system (P) intended to be connected to an electrical power distribution network (GRID) through respective connection means (MU) for supplying user circuits and apparatus (L) in a normal operation condition, and comprising:

a network of power conductors equipped with load connecting means (S) for the plug-in of said user apparatus (L); and

an automatic failure control unit (CU_M), adapted to detect availability of electrical power from the distribution network (GRID) and arranged for emitting a control signal (SPLC) to auxiliary generating means (G) which may be previously associated with the system (P), in the case of interruption of the power supply from said network (GRID), characterized in that said automatic failure control unit (CU ) has a control signal output (CTRL) connected to the network of power conductors downstream of the connection means (MU), and is arranged for transmitting said control signal (SPLC) as a powerline communication signal on the power conductors of the network towards at least one of the load connecting means (S) available for the plug-in of the auxiliary generating means (G).

2. System (P) according to Claim 1, wherein said connection means comprise contactor means (SW) adapted to establish (or break) a connection to the distribution network (GRID), characterized in that said automatic failure control unit (CUM) is associated with said contactor means (SW) and arranged for detecting the network operating voltage upstream of said contactor means (SW).

3. System (P) according to Claim 2, characterized in that said automatic failure control unit (CUM) is further arranged for detecting the network operating voltage downstream of said contactor means (SW).

4. System (P) according to any one of the preceding claims, wherein said automatic failure control unit (CUM) is arranged for:

- in case of interruption of the power supply from the distribution network (GRID), emitting a control signal (SPLC) including an instruction for activation of the auxiliary generating means (G),

and then

- emitting a control signal (SPLC) including an instruction for de-activation of the auxiliary generating means (G) when availability of electrical power from the external network (GRID) is reset, and

- allowing resetting of said contactor means (SW) following de-activation of the auxiliary generating means (G).

5. System (P) according to any one of the preceding claims, wherein said automatic failure control unit (CUM) is arranged to receive state signals transmitted as powerline communication signals on the power conductors of the network.

6. System (P) according to any one of the preceding claims, wherein said automatic failure control unit (CUM) is adapted to output signals for controlling user apparatus (L) connectable to the system (P) by means of a respective load connecting means (S).

7. System (P) according to Claim 6, wherein said automatic failure control unit (CUM), in a condition of auxiliary supply of the network of conductors of the system, is arranged for emitting signals for the selective activation and de-activation of user apparatus (L) connectable to the system (P) as a function of the electrical power which may be supplied by said auxiliary generating means (G), according to a predetermined priority criterion of said user apparatus.

8. Generator set (G), including an electrical generator and a corresponding thermal engine for operation thereof, adapted to be connected to one of the load connecting means

(S) for the plug-in of user apparatus (L) of an electrical system (P) according to any of Claims 1 to 7, comprising a control unit (CUQ) adapted to receive a control signal (SPLC) output from the automatic failure control unit (CUM) associated with the system (P) and conveyed on the power conductors of the network, and arranged for executing an instruction of activation or an instruction of de-activation of the generator set (G).

9. Generator set (G) according to Claim 8, wherein said control unit (CUQ) of the generator set (G) is arranged for emitting a state signal representative of the activation or de-activation state of the set (G), adapted to be transmitted as a powerline communication signal on the power conductors of the network towards the automatic failure control unit (CUM) associated with the system (P).

10. Integrated power supply system, including a local electrical system (P) according to any of Claims 1 to 7, and an auxiliary generator set (G) according to either of Claims 8 and 9, plugged into one of the load connecting means (S) of the system (P), adapted for the plug-in of user apparatus (L).