System and method for regulating a load voltage in power distribution circuits

(54) Title: SYSTEM FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS AND METHOD FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS (73) Owner (s): Siemens ltda (72) Inventor (s): Martin Alsina Navarro (57) Abstract: SYSTEM FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS AND METHOD FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS. The present invention relates to a system for regulating load voltage (O) in power distribution circuits comprising at least: a regulating transformer (2) operatively arranged in series between a power supply (F) and the load (C), the power supply (F) being able to provide a supply voltage (VAL) to the load (O); a measuring device (5) operatively associated with the load (O), the measuring device (5) being able to measure at least one value of an electrical load signal (SCA); a control device (4) operatively associated with the measuring device (5), the control device (4) being able to compare the value of the electrical charge signal (SOA) with a pre-established reference value (VRE) and provide a electrical correction signal (SOO); and an actuation device (3) operatively associated with the control device (4), the actuation device (3) being able to provide an adjustment voltage (VAJ) proportional to the electrical correction signal (500), the voltage adjustment (VAJ) being applicable to fixed electrical taps of the primary winding of the regulating transformer (2), the fixed electrical taps remain immobile when the adjustment voltage (VAJ) changes, the regulation transformer (2) being able to transform the adjustment voltage (VAJ) into a regulation voltage (VRE), the regulation voltage (VRE) being added in module and phase to the supply voltage (VAL). The present invention also relates to a method to be performed on the aforementioned system.

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Descriptive Report of the Invention Patent for SYSTEM FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS AND METHOD FOR REGULATING LOAD VOLTAGE IN ENERGY DISTRIBUTION CIRCUITS.

The present invention relates to a system for regulating a load voltage of power distribution circuits. More particularly, the invention relates to a system capable of automatically adjusting a voltage provided by an energy distribution circuit to at least one load, increasing or decreasing its value, according to variations in electrical signal measurements of said load.

The present invention also relates to a method for regulating the load voltage in power transmission and distribution circuits.

Description of the State of the Art

In the transmission and distribution circuits of electrical energy, it is necessary that the voltage supplied to the user be kept constant in order to avoid disturbances such as, for example, malfunction and damage to industrial equipment, appliances, electronics and computers. For this, equipment is used that makes it possible to increase or decrease the voltage according to the demand demanded. Due to various factors, such as changes in the load, voltage regulators and / or transformers are used together with on-load tap-changers capable of changing the voltage automatically, without interrupting the power supply to the user.

The voltage regulator basically comprises a transformer equipped with a winding provided with taps or taps, with a certain ratio of turns, connected to a mechanical switch under load. Normally, the mechanical commutator is mounted inside a tank comprised by the transformer, submerged in an insulating oil (mineral oil). In this sense, this tank must have its volume oversized due to the need to install the switch in its internal portion, which also leads to an increase in the volume of the insulating liquid.

Some types of voltage regulators also include a reactor connected to the contacts of the switch, to limit the electric current and allow an intermediate voltage between two positions of said taps.

Generally, the position of the taps connection to a mechanical switch is automatically changed by a control system, which measures the load current from an electronic panel and commands the switch to start from the load voltage. Switching to a tap defined by the control system is done mechanically by moving the moving contacts that slide over the surface of the fixed contacts distributed in a circle, avoiding interruption of the power supply. The said displacement between taps requires an electric motor and other mechanical parts, such as gears, supports, among others, being

Ϊ5 that with each tap change an electrical arc is generated between the mobile contact and the fixed contact.

Such an electric arc removes metallic particles from the contacts, causing them to wear out and contributing to the formation of flammable gases that contaminate its insulating oil, reducing its insulation characteristics and even causing an explosion risk under certain conditions.

In addition, there are voltage regulators capable of changing the direction of current flow in the taps and thereby changing their polarity, allowing the regulation to be in the direction of increasing or decreasing the required voltage according to the position of the taps, where each tap corresponds to a certain ratio of turns, then being added or subtracted according to the switch's polarity.

However, because the switch is mechanical and rotated over the transformer windings, there is a disadvantage of limiting the adjustment of the output voltage to a fixed and limited number of switch positions, in addition to the generation of electrical arcs in each change of position, as previously mentioned.

In this way, commutators are subjected to constant wear, requiring periodic maintenance for cleaning and even for their replacement, requiring the transport of the regulators to a suitable location, involving undesirable expenses and inconveniences. This transport contributes to the increased risk of leakage of insulating oil in an eventual accident, thus threatening the environment and people. Additionally, transportation requires spending on human resources, facilities, vehicles, fuel, among others. These expenses are passed on to consumers through tariffs.

Such dangerous situations, as well as the high costs involved in frequent maintenance of the voltage regulator, could be reduced and / or avoided if the mechanical switch was replaced by a system that increased or decreased the output voltage, without generating electrical arcs and without use insulating oil.

Some of the problems mentioned above are detected in the following solutions, known from the state of the art, presented below.

PI 0110005-0 describes a switching transformer connected to the input terminals of a voltage source Ve to be regulated. Such a transformer has a variable turn ratio k in order to generate a kV voltage on its secondary_AND. This turn ratio is controlled by control and control devices depending on the output voltage Vs of the voltage adapter. The kV voltage_AND it is powered by a second transformer with fixed turn ratio k ', connected in series to the output of the voltage adapter. The transformer generates a k'kV voltage_AND on its secondary which is added to the output voltage V_s adapter. This arrangement is applicable only for a low voltage network, in addition to comprising mechanical switches that have the disadvantage of limiting the regulation of the output voltage to a fixed number of activated switches, and there is still the generation of electric arcs at each change of actuation .

British document GB 2324389 describes a transformer whose secondary is connected in series to a controlled voltage line, to add or subtract voltage to the line. The primary of this transformer is coupled to a switching network formed by a transformer with a variable winding ratio, which is controlled by a loop comprising a microprocessor and 4 relays. This arrangement also comprises contacts closed by relays, limiting the modification of the output voltage to a fixed number of activated contacts, in addition to generating electrical arcs at each change of actuation.

In this way, state of the art documents do not describe a complete and satisfactory solution to solve all existing problems, in addition to apparently having a high cost of implementation and maintenance.

Objectives of the invention

A first objective of the present invention is to provide a system capable of automatically regulating an electrical voltage supplied to a load comprised by an electrical distribution circuit, without the need to interrupt the supply of electrical energy to the load, in order to reduce and simplify the maintenance and exchanges required by systems known to the state of the art, while reducing costs and risks to the environment and people.

A second object of the present invention is to provide a method for automatically regulating a voltage supplied to a load circuit by a distribution of electric power. Brief Description of the Invention

The first objective of the present invention is achieved through the provision of a system for regulating the load voltage in power distribution circuits comprising at least: a regulating transformer with a primary winding and a secondary winding, the secondary winding of the power transformer. regulation being operatively arranged in series between a power supply and the load, the power supply being able to provide a supply voltage to the load; a measuring device operatively associated with the load, the measuring device being able to measure at least one value of an electrical signal from the load; a control device operatively associated with the measuring device, the control device being able to compare the electrical signal value of the load with a pre-established reference value and provide an electrical correction signal; and an actuation device operatively associated with the control device, the actuation device being able to provide an adjustment voltage proportional to the electrical correction signal, the adjustment voltage being applicable in fixed electrical derivations of the primary winding of the regulation transformer , the fixed electrical leads remain immobile when the adjustment voltage changes, the regulation transformer being able to transform the adjustment voltage applied in the primary winding into a regulation voltage in the secondary winding, the regulation voltage being added in module and phase to the supply voltage.

The second objective of the present invention is achieved by providing a method that comprises the steps of: i) supplying a supply voltage to the load; ii) measurement of at least one value of an electrical load signal; iii) comparison between at least one value of the electrical signal of the load obtained in step ii with a pre-established reference value; iv) calculation and providing an electrical signal correction; v) provision of a tuning voltage from the electrical signal obtained in step iv correction; vi) transformation of the adjustment voltage obtained in step v into a regulation voltage; vii) sum in module and phase of the regulation voltage obtained in step iv with the supply voltage; and viii) supply of the sum of stresses obtained in step vii for the load.

Brief Description of Drawings

The present invention will be described in more detail below, with reference to the accompanying drawings, in which:

figure 1 - represents a schematic block diagram of a system for regulating load voltage in power distribution circuits, object of the present invention; and figure 2 - represents a flowchart of a method for regulating the load voltage in power distribution circuits.

Detailed Description of the Figures

Figure 1 illustrates a schematic block diagram of a system for regulating load voltage C in power distribution circuits, according to a preferred embodiment of the present invention.

The energy distribution circuit preferably consists of a circuit capable of providing electrical power to C loads, such as, for example, homes, homes, buildings, condominiums, factories, industrial plants, as well as power stations and substations. Thus, the system for regulating the present invention is preferably applicable to high voltage circuits, for example, on the order of 13800 V, 24200 V or 34500 V. Optionally, the system can also be applied to medium and / or low voltage circuits.

As can be seen in figure 1, such a system comprises at least one power supply F capable of supplying a voltage supply VAL to load C.

Load C is associated with a regulating transformer 2 with a primary winding and a secondary winding operatively arranged in series between power supply F and load C.

The load C is also operatively associated with the measuring device 5 capable of measuring at least one value of an electrical signal from the SCA load.

The measuring device 5 is preferably, but not necessarily, in a multimeter capable of measuring a load voltage signal and / or load current signal.

The voltage measuring device 5 is operatively associated with a control device 4 capable of comparing the value of the electrical signal of the SCA load with a pre-established reference value. This reference value consists of a value considered optimal, proportional to an ideal voltage value that you want to supply to load C.

The control device 4 is also capable of providing an electrical signal for SCO correction which can be a voltage or electric current, depending on the system implementation.

Preferably, the control device 4 comprises at least one microprocessor or a microcontroller capable of executing a computer program that allows the provision of the electrical correction signal SCO. The SCO correction electrical signal consists of a digital and / or analog electrical signal that can be provided directly by a microprocessor or microcontroller output pin, or it can also be provided by a filter (circuit or electrical component) associated with said pin. output. The computer program can be stored in an external memory associated with the microprocessor or microcontroller or stored in an internal memory of the microprocessor or microcontroller.

In this way, the comparison, calculation and provision of the SCO correction electrical signal are performed by a control algorithm contained in the computer program.

In addition, an allowable tolerance value (error) can also be established, and control device 4 is configured to provide the SCO correction electrical signal only when the electrical signal value of the SCA load is exceeded beyond the limits determined by this tolerance. Optionally, control device 4 can be configured to provide the SCO correction electrical signal at all times, regardless of the magnitude of difference between the electrical signal value of the SCA load and the pre-established reference value. In addition, other parameters can be included, if necessary.

Of course, both the pre-established reference value and the tolerance value can be adjusted and changed according to the application, convenience and need.

The control device 4 further comprises an interface panel for interaction with an operator. The interface panel is equipped with visualization means (example LCD display) and control buttons / keys.

Alternatively, the control device 4 can be implemented entirely by analog electronic components and or integrated circuits (chips) operatively associated with each other, in order to dispense with the use of a microprocessor or a microcontroller.

The control device 4 is operatively associated with an actuation device 3 capable of providing a VAJ adjustment voltage, proportional to the SCO correction electrical signal, to the regulating transformer 2. More particularly, the VAJ adjustment voltage is applicable in taps fixed electrical currents of the primary winding of regulating transformer 2. This adjustment voltage VAJ is transformed by regulating transformer 2 into a regulating voltage VRE in its secondary winding.

Bearing in mind that the secondary winding of the regulating transformer is associated in series between the power supply F and the load C, the regulating voltage VRE is added in module and phase to the supply voltage VAL, in order to correct or adjust the voltage provided to load C, according to the demands and variations presented by the energy distribution circuit. In this way, the fixed electrical taps remain immobile when there is some variation in the VAJ adjustment voltage. The correction (adjustment) of the voltage provided to load C is done entirely electronically, without involving any type of movement of mechanical parts.

Thus, unlike systems known in the prior art, the system of the present invention does not use mobile mechanical contacts that generate electrical arcs capable of accelerating wear and requiring frequent maintenance.

In addition, the system of the present invention eliminates the use of insulating oil, eliminating the risk of contamination of the environment, fire and explosion during its implementation, maintenance and eventual transportation that may be necessary.

Additionally, the system of the present invention dispenses with the use of an electric motor and other mechanical parts, such as gears, supports, among others, which simplifies and reduces the final costs involved in its implementation and maintenance.

Furthermore, the VRE regulation voltage variation is made continuously, without voltage steps, which allows for finer and more accurate voltage adjustments, optimizing equipment performance and saving energy.

It should also be noted that the measurement, comparison, correction / adjustment, transformation, sum and supply of the corrected voltage to load C is performed automatically by the system, according to variations in the measurement of voltage or current of load C, without no type of power interruption occurs.

The actuating device 3 comprises at least one power circuit capable of handling the electrical correction signal SCO to supply the VAJ adjustment voltage. As previously described, the value of the adjustment voltage VAJ is proportional to the value of the electrical correction signal SCO.

The internal power circuit is equipped, for example, with at least one AC / DC converter and / or a DC / AC converter and / or amplifier circuits. AC / DC, DC / AC converters and amplifier circuits are widely known in the prior art and will not be the subject of discussion.

Therefore, the specific configuration of the actuation device 3 can vary according to the convenience and needs of use, being irrelevant for the definition of the protection scope of the invention.

The actuation device 3 is electrically powered by an auxiliary transformer 1, as can be seen in figure 1. In this way, the auxiliary transformer 1, operatively arranged between the power supply F and the actuation device 3, is capable of providing a auxiliary voltage VAU to actuating device 3.

Auxiliary transformer 1 preferably consists of a power transformer. Such a transformer has a high voltage side (primary winding) associated with the power supply F and a low voltage side associated with the actuation device 3.

Thus, a reduced risk of accidents is obtained when accessing and / or maintaining the actuation device 3, control device 4 and the regulating transformer 2, since all control to supply the regulating voltage VRE is done from the side low voltage.

Figure 2 illustrates a flow chart of the steps performed by the system of the present invention. These steps make up a method for regulating the voltage of load C in power distribution circuits.

This method comprises the steps of:

i) supplying a VAL supply voltage to load C;

ii) measuring at least one value of a load electrical signal

SCA;

iii) comparison between at least one value of the electrical signal of the SCA load obtained in step ii with a pre-established reference value;

iv) calculation and provision of an SCO correction electrical signal, preferably, if the result of the comparison in step iii is not included in a pre-established tolerance range;

v) providing a VAJ adjustment voltage from the SCO correction electrical signal obtained in step iv;

vi) transformation of the adjustment voltage VAJ obtained in step v into a regulation voltage VRE;

vii) sum in module and phase of the regulation voltage VRE obtained in step iv with the supply voltage VAL; and viii) supply of the sum of stresses obtained in step vii for load C.

In step iii above, the comparison can be made, for example, by calculating the difference in module and phase between the electrical signal of the SCA load and the pre-established reference value.

Having described an example of a preferred embodiment, it should be understood that the scope of the present invention covers other possible variations, being limited only by the content of the appended claims, where possible equivalents are included.