Method and apparatus for collecting data related to the status of an electrical power system

A method and an apparatus for collecting data related to a status of an electrical power system, wherein data is continuously acquired from the electrical power system and is stored, at least temporarily, in a first volatile memory. Upon the occurrence of an event, the data stored in the first volatile memory is copied and permanently stored in a second non-volatile memory.

BACKGROUND OF THE INVENTION

The present invention relates to a method and an apparatus for collecting data related to a status of an electrical power system.

As it is known, protective relays are widely used in electrical power systems. Such relays are used to monitor the functioning of the power systems and upon the occurrence of predetermined operating conditions to intervene and protect the systems from possible incoming faults and damages. This is typically accomplished by tripping an associated circuit breaker.

With the introduction of microprocessor-based electronic relays, the possibility to store data related to the status of the power system under various operating conditions, in particular at the time before, during, and after the tripping of the associated circuit breaker, and including also the inputs and outputs of the relay itself under such conditions, has become a customary requirement and a necessity for proper analyses.

To this end, many different solutions have been implemented using the various types of electronic memories presently available. The existing solutions are designed case by case by having the relay treats some specific performances and functionalities as privileged, whereas some others are partially or even completely relinquished. For example, in some cases the data stored under operating conditions are completely lost when the power feeding the relay is for some reasons switched off, in some other applications the rate between the cost of the storing units and the quantity of data that they can store is not optimized, or the access time to the storing unit is not fast enough, or the number of times that data can be stored/erased is to some extent limited, et cetera.

It would be therefore desirable to provide a solution which allows to optimize the actual relay architecture and achieve a better compromise among various possible performances and functionalities with respect to the existing solutions when collecting data related to the various states of an electric power system.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method for collecting data related to a status of an electrical power system operatively coupled with a microprocessor-based relay is provided. The method comprises:acquiring data from said electrical power system;storing at least temporarily the acquired data in a first volatile memory; andupon the occurrence of an event, copying the data stored in said first volatile memory and permanently storing the copied data in a second non-volatile memory.

Further, the present invention provides for an electronic relay for collecting data related to a status of an electrical power system operatively coupled therewith. The relay comprises:a microprocessor for acquiring data from said electrical power system;at least a first volatile memory for storing the acquired data; anda second non-volatile memory for permanently storing thereon data copied from said first volatile memory upon the occurrence of an event.

The present invention also encompasses an electronic relay for collecting data related to a status of an electrical power system operatively coupled therewith, comprising:a microprocessor, a first volatile memory for at least temporarily storing data, and a second non-volatile memory for permanently storing data thereon, wherein said microprocessor has thereon computer usable program code configured to:acquire data from said electrical power system;store the acquired data in said first volatile memory; andupon the occurrence of an event, copy the data stored in said first volatile memory and permanently store the copied data in a second non-volatile memory.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

It should be noted that in the detailed description that follows, identical components have the same reference numerals, regardless of whether they are shown in different embodiments of the present invention. It should also be noted that in order to clearly and concisely disclose the present invention, the drawings may not necessarily be to scale and certain features of the invention may be shown in somewhat schematic form.

FIG. 1illustrates an electronic microprocessor-based relay, indicated by the overall reference number1, which is used in a power system200comprising an electrical line, schematically represented by the reference number201and a plurality of devices operatively coupled therewith, such as loads, electrical equipments, components et cetera, which are represented by the various blocks202.

As illustrated inFIG. 2, the method according to the present invention foresees a first phase101where, under operating conditions, data related to the status of the electrical power system200are continuously acquired by the microprocessor2of the relay1. Such a microprocessor can be for example a Motorola Coldfire processor or Analog Devices Blackfin and comprises, according to solutions well known in the art and therefore here not described in details, application code running thereon and/or an operating system (OS), and/or a real-time operating system (RTOS) such as for example uClinux or Quadros.

In a phase102the acquired data are stored, at least temporarily, in at least one storing unit. Such storing unit is preferably constituted by a dedicated first volatile memory3which is operatively coupled to the microprocessor2. Preferably, such a volatile memory3is constituted by a low power SRAM (Static Random Access Memory), such as for example Cypress Low-Powered CY62148VLL.

In addition, the acquired data can be temporarily stored also in a system memory4operatively coupled to the microprocessor2. The system memory4is constituted by a volatile memory which is larger than the first memory3.

Under normal operating conditions, data are continuously acquired and stored in the SRAM memory unit3which allows to have an ideally non-limited number of writing/erasing operations.

Upon the occurrence and detection of an event103indicative of a particular condition which requires related data to be permanently saved, in a phase104the data stored in the first volatile memory3is copied by the microprocessor2. Then, in a phase105, the copied data are written and permanently stored in a second non-volatile memory5also operatively associated with the microprocessor2. Preferably the non-volatile memory5is a NAND flash memory, such as for example ST Micro NAND01GW.

Possible events that may require to permanently store data corresponding to such states of the power system are for example, but not limited to: tripping of a circuit breaker (not illustrated) associated with the relay1so as to interrupt the flow of current along the line201; external I/O commands coming from other devices, such as for example inputs from users on a control panel; record of data triggered by a logic internal to the relay, for example for periodic monitoring; switching off and thereafter on the power feeding the relay, et cetera.

In particular, the relay1comprises an electronic logic circuit6for operatively interfacing the microprocessor with the NAND flash memory5. An example of such an electronic logic circuit is illustrated inFIG. 3. Alternatively, the relay can have a dedicated port for directly connecting with the NAND flash memory5.

The method according to the invention foresees a phase106where it is verified if the data copied from the first volatile memory3has been correctly stored in the non-volatile memory5. When the result of this verification turns out to be negative, i.e. the data copied from the first volatile memory3has not been correctly stored in the second non-volatile memory5, there is a phase107where it is tried again to permanently store in the second non-volatile memory5the data copied from the first volatile memory3.

This attempt is repeated until it results from a step108that the data copied is successfully stored in the non-volatile memory5.

In particular, the relay1comprises a driver7for writing, i.e. storing the data copied in the second non volatile memory5, and comparing the data stored in the second non volatile memory with data copied from the first volatile memory3. In practice, the driver7, which is preferably constituted by a software module embedded into the microprocessor2, tries to write onto the NAND flash memory5the data copied by the microprocessor2from the first memory3. The driver7then reads data back from the NAND flash memory5and compares what it tried to write on the memory5itself versus what it reads back. If the data is not the same the driver7will then try to write the data in a block(s) of the memory5different from the block(s) where it tried to write during the previous attempt. The driver7will continue to carry out these operations until it reads back what it tried to write in the memory5, i.e. until there is a confirmation that data copied from the first memory3is correctly stored in the second memory5.

Alternatively, the driver7may be realized as a part of the hardware of the microprocessor2.

In a preferred embodiment of the present invention, the first volatile memory3is provided with a source of auxiliary power. Preferably, such a memory3is constituted by a low power battery-backed SRAM. In this way the memory3is transformed into a non-volatile memory and can permanently store data if needed, for example when power feeding the relay is switched off, thus preventing to loose relevant data related to this operating condition.

Accordingly, upon the occurrence of a condition when the power feeding the relay1is switched off data is permanently stored in the memory3thanks to the auxiliary source of power. In this case, when the power is switched on again (condition indicated by reference109), the method according to the invention foresees a phase110where it is verified if pertinent data stored in the first volatile memory3before the power feeding the relay1was switched off matches with the data stored in the second non-volatile memory5.

When the data stored in the first volatile memory3before the power feeding the relay1was switched off does not match with the data stored in the second non-volatile memory5, a phase104is carried out again as described above. Therefore, the data stored in the first volatile memory3before the power feeding the relay1is switched off is first copied and then, at phase105, permanently stored in the second non-volatile memory5. Also in this operating condition, phases106-108are carried out, i.e. it is first verified if the relevant data has been correctly stored in the second non-volatile memory5. If this is not the case, there is a new attempt to permanently store in the second non-volatile memory5the data stored in the first memory5in an another block of memory different from the one where the previous attempt was made. This attempt is repeated until it results from step108that the data copied are successfully stored in the non-volatile memory5.

It is to be understood that the description of the foregoing exemplary embodiment(s) is (are) intended to be only illustrative, rather than exhaustive, of the present invention. Those of ordinary skill will be able to make certain additions, deletions, and/or modifications to the embodiment(s) of the disclosed subject matter without departing from the spirit of the invention or its scope, as defined by the appended claims.