METHOD FOR CONTROLLING A VOLTAGE CONDITIONING UNIT

Abstract

A method and system for controlling a microcontroller-based three-phase voltage conditioner characterized by comprising a primary coil and four secondary coils, by which five regulation states are achieved.

Description

METHOD FOR CONTROLLING A VOLTAGE CONDITIONING UNIT BACKGROUND OF THE INVENTION A. FIELD OF THE INVENTION The present invention relates to methods for controlling regulating transformers and, more particularly, to a control method for a five-stage, three-phase voltage conditioning unit having one primary coil and four secondary coils for correcting the input voltage. B. DESCRIPTION OF RELATED ART The method of the present invention is specifically designed to control a microcontroller-based three-phase voltage conditioner comprising one primary coil and four secondary coils. The same coils are connected in one direction to increase voltage and in the opposite direction to decrease voltage. The switching electronics are either TRIACs or SCRs and achieve an output tolerance range of 2%. The method of the present invention has the main function of enabling / disabling power semiconductors in the appropriate sequence to achieve the regulation functions without this process being fixed as in many of the current regulation topologies, but rather allowing the regulator to adapt to the load conditions present on the line. SUMMARY OF THE INVENTION Therefore, a primary objective of the present invention is to provide a method and system for controlling a microcontroller-based three-phase voltage conditioner characterized by comprising a primary coil and four secondary coils, using the same coils connected in one direction to raise the voltage and connected in another direction to lower the voltage. Another main objective of the present invention is to provide a method and system for controlling a microcontroller-based three-phase voltage conditioner of the above-described nature, wherein the switching electronics are by TRIACs or SCRs. Another main objective of the present invention is to provide a method and system for controlling a microcontroller-based three-phase voltage conditioner of the nature described above, which has the main function of enabling / disabling power semiconductors in the appropriate sequence to achieve the regulation functions without this process being fixed as in many of the current regulation topologies, but rather allowing the regulator to adapt to the load conditions present on the line. These and other objectives and advantages of the present invention will become apparent to persons with normal knowledge in the field from the following detailed description of the invention. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic of the circuit for controlling the taps of the regulating transformer. Figure 2 is a connection diagram of the NA1 combined coil activation. Figure 3 is a connection diagram for the NA2 combined coil activation. Figure 4 is a connection diagram for NC1 combined coil activation. Figure 5 is a combined NC2 coil activation connection diagram. Figure 6 is a flowchart of the method of the present invention. Figure 7 is a representation of the regulating funnel that represents the operation of the method of the present invention. Figure 8 is an alternative representation of the regulating funnel that represents the operation of the method of the present invention. Figure 9 is a graphical representation of the state transition matrix. Figure 10 is a graphical representation of the interrupt handling (ISR) form bocnnn / 77n7 / e / YiAi DETAILED DESCRIPTION OF THE INVENTION The method and system of the present invention will be described by reference to the description of the three-phase voltage conditioner for which it is designed, the circuit diagram of which is shown in Figure 1. The reference three-phase voltage conditioner comprises the following elements: an autotransformer that has a primary coil N1 and four secondary coils N2, N3, N4 and N5 respectively, where a combination of specific coils can be connected to achieve the desired output voltage and even use the same coils connected in one direction to raise the voltage and connected in another direction to lower the voltage; power electronics for switching electric current, comprising a plurality of TRIAOS or SCRs for activating the autotransformer coils; Means to detect operating conditions of the autotransformer, specifically measurement of effective voltage, measurement of current, measurement of power, measurement of energy, measurement of power factor. digital control electronics connected to the power electronics and the means to detect operating conditions of the autotransformer by means of a UART-type communication interface, wherein the digital control electronics comprises a microcontroller (PLC). Where, in a preferred embodiment, each of the coils has the following number of "turns" of copper wire: • Coil N2: 12 turns • Coil N3: 120 turns • Coil N4: 120 turns • Coil N5: 12 turns Figure 1 shows a diagram of the autotransformer including all its bQcnnn / zznz / E / YiAi connections. Operation of the autotransformer. The voltage conditioner achieves five levels of regulation with respect to the input voltage, where each regulation level is achieved by connecting two or more secondary coils N1, N2, N3, or N4, which form a single coil. These are referred to in this document as NO combined coils, which serve to increase the voltage, and NC combined coils, which serve to decrease the voltage. The voltage conditioner being described is designed to provide the following combined coils: • Combined coils to increase voltage: NA1 or NA2 • Combined coils to decrease voltage: NC1 or NC2 • Combined coil to maintain input voltage: NB NA1 Combined Coil Activation The connection scheme of the secondary coils for the activation of the combined coil NA1 is shown in Figure 2, it is carried out when the means for detecting operating conditions detect a very low input voltage (the specific parameters will be described in the method description). In this connection scheme, the digital control electronics send a signal to the power electronics to activate the secondary coils N2 and N3 such that: NA1= N2 + N3 NA2 Combined Coil Activation The connection scheme of the secondary coils for the activation of the combined coil NA2 is shown in Figure 3, it is carried out when the means for detecting operating conditions detect a low input voltage (the specific parameters will be described in the method description). In this connection scheme, the digital control electronics send a signal to the power electronics to activate the secondary coils N2, N3 and N4 such that: NA2= N2 + N3 + N4 bocnnn / 77n7 / e / YiAi NC1 Combined Coil Activation The connection scheme of the secondary coils for the activation of the combined coil NC1 is shown in Figure 4, it is carried out when the means for detecting operating conditions detect a high input voltage (the specific parameters will be described in the method description). In this connection scheme, the digital control electronics send a signal to the power electronics to activate the secondary coils N3, N4 and N5 such that: NC1 = N3 + N4 + N5 NC2 Combined Coil Activation The connection scheme of the secondary coils for the activation of the combined coil NA1 is shown in Figure 5, it is carried out when the means for detecting operating conditions detect a very high input voltage (the specific parameters will be described in the method description). In this connection scheme, the digital control electronics send a signal to the power electronics to activate the secondary coils N2, N3 and N4 such that: NC2 = N4 + N5 NB Combined Coil Activation When the supply voltage is within the acceptable range, it is desirable that the voltage entering be equal to the voltage leaving the voltage conditioner. In this connection scheme, the digital control electronics send a signal to the power electronics to activate the secondary coils N3 and N4 such that: NB= N3 + N4 Means for detecting autotransformer operating conditions: Voltage measurement The means for detecting the operating conditions of the autotransformer are performed by measuring the input and output voltage of the autotransformer. This information is provided to the digital control electronics so that it activates the appropriate combined coil to raise or lower the voltage to the appropriate levels, within a range of + / - 2%. Because the described voltage conditioner is connected to a three-phase system, the means for detecting operating conditions of the autotransformer detect six voltage readings, i.e., three input voltages and three output voltages. The type of measurement performed by these devices is the effective voltage measurement, also known as RMS (Root Mean Square) voltage measurement. This is done by taking discrete samples of the waveform, squaring each sample, summing all the samples obtained over a period of 8.3 milliseconds, and then taking the square root of the sum of the squared values. This type of measurement is more accurate than others because it eliminates the distortion introduced into the electrical network by all connected loads. The types of loads that distort the voltage waveform include non-linear loads, inductive loads, and capacitive loads. Current measurement For the voltage conditioner to perform its voltage regulation function, the digital control electronics must send a signal to the power electronics to activate and deactivate the appropriate secondary coils. When turning off the coil, it is vital that this happens at the correct voltage point, that is, close to zero volts. This ensures that when the digital control electronics send the signal to turn off an SCR or TRIAC, it actually turns off. It is very important that it does not remain on because if, when another SCR or TRIAC is turned on, the element that received the turn-off signal is not off, it would cause a high current draw. For a switching device like an SCR or TRIAC to turn off, its gate (G) must be turned off and the main current waveform between terminals MT1(K) and MT2(A) must be less than the holding current of the SCR or TRIAC used in the circuit. If these two conditions are not met, the SCR or TRIAC remains on until the main current falls below the holding current. Therefore, it is very important to measure the current waveform to determine when the current crosses zero, because the SCR remains on until it reaches zero amperes. Knowing the zero crossing of the current allows you to decide the best time to turn on the SCR or TRIAC that will activate the coil selected by the control. This is necessary to ensure that when the command to turn on the selected SCR or TRIAC is given, the previous SCR or TRIAC is already off. If it were not off, turning on the selected one would cause an excessive current draw, leading to electrical disturbances in the power supply and potential damage to the electrical components in the control circuit. The zero crossing point of the current is a variable that changes according to the type and amount of load connected; that is, it is dynamic and depends on whether the load is resistive, inductive, capacitive, or nonlinear. The means for detecting operating conditions of the autotransformer measure the zero crossing of the voltage, and also the zero crossing of the current so that the digital control electronics can calculate the best time to turn off an SCR or TRIAC and turn on the selected SCR or TRIAC. Power measurement The voltage and current measurements per phase, taken by the equipment used to detect the operating conditions of the autotransformer, provide the main components for power measurement. The concept of power measurement encompasses the measurement of the three types of power present in a power supply circuit: Apparent Power, Real Power, and Reactive Power. These power levels are dynamic, meaning they change according to how the power consumption of the loads connected to the voltage regulator varies. bocnnn / 77n7 / e / YiAi This measurement makes it possible to know the amount of load that is connected and thus know if the autotransformer is operating within its capacity or is being exceeded or overloaded. This measurement makes it possible to know if the autotransformer is operating within its capacity or is overloaded, and in the case that it is overloaded the digital control electronics can make the autotransformer cut off the output, that is, disconnect the load and thus avoid damage to the autotransformer or the electrical wiring, preventing unsafe conditions. Energy measurement The concept of energy is the result of multiplying the power being consumed by the time it is consumed. Digital control electronics, equipped with a real-time clock and power measurement, provide the two main components necessary for quantifying the amount of energy being consumed. Similar to power, energy is measured in Apparent Energy, Real Energy, and Reactive Energy. With this information, the digital control electronics can calculate the cost of the energy consumed by the load connected to the regulator. Power factor measurement Power factor measurement is crucial for determining the correct switching on and off of TRIACs or SCRs. The power factor is the phase difference between the voltage and current waveforms. Because the power factor is dynamic, it's essential to measure it continuously. Measuring the power factor helps determine when the current and voltage waveforms are approaching zero crossing, which is the optimal time to switch the SCR or TRIAC on or off. Switching SCRs or TRIACs on and off at the appropriate time prevents electrical disturbances, since the switching of power components is done with values ​​close to zero in voltage and current. bocnnn / 77n7 / e / YiAi Using this power factor measurement improves the performance of the voltage regulator. Power electronics The power electronics of the described voltage regulator comprise digital output ports (GPIO) that control one or more neutral-referenced SCRs or TRIACs and one or more line-referenced SCRs or TRIACs. To turn on the line-referenced SCRs, a high pulse is applied to the line, and to turn on a neutral-referenced SCR or TRIAC, a high voltage pulse is applied to the neutral. Since a control circuit cannot have two different references, two independent power supplies must be developed, each with its own reference. Likewise, the digital control electronics must optically isolate the signals it sends to the SCRs or TRIACs so that they can be coupled to their reference without problems. Power semiconductors, SCRs or TRIACs depending on the current to be handled, are part of a circuit called an H-circuit (Figure 1), which, depending on the switching sequence and by polarizing the coils or taps of the transformer appropriately, generate the effect of raising, lowering or keeping the input voltage equal to the output voltage, as long as the input voltage and the output voltage are referenced to the same neutral. Voltage regulator control method Before describing the method, which is represented in Figure 6, it is necessary to define the following terms. • Timer 2 interrupt routines (TMR2 overflows at 5.58 ms): This routine has the function of executing the transition from the current state to the next state. • Timer 3 interrupt routines (TMR3 overflows every 100 ms): This routine has the function of obtaining electrical parameters. bocnnn / 77n7 / e / YiAi • Logic Level Change Notification Routine: This routine has the function of detecting zero crossing of voltage and current signals and calculating the zero crossing time between phases. The control method carried out entirely by the microcontroller of the digital control electronics is described below: a) Initialize timers TMR2 and TMR3 to zero and configure the overflow times. In a preferred mode, TMR2 overflows at 5.58 ms and TMR3 overflows at 100 ms as described above; b) Start the execution of an infinite state machine comprising the following stages: 1. Start TMR3 2. Execute the following TMR3 interrupt routines when TMR3 overflows at 100ms, for each phase: I. Obtain information from three electrical sensors to obtain the electrical parameters of the input and output through the UART type communication interface, the information obtained is: voltage, current, power, energy and power factor; II. Classify the transformer state, input state, and regulation state based on the information obtained from step I. The manner in which these states are classified will be indicated later; II I. Check the consistency between the input state, the transformer state, and the output state of each phase to validate the correct operation of the regulation. If there is no consistency, it is determined that the equipment is in an internal error state, and the equipment is switched to a transparent state where the input equals the output. The consistency check involves reading the input voltage and the output voltage and comparing them with the theoretical output value. If the output voltage value corresponds to the input voltage multiplied by the factor of the current regulation state, then consistency exists. However, if the output value does not correspond to the calculated value, then consistency does not exist. IV. Using the information obtained from points I and II, process a regulation state machine, which determines whether to execute a transition and which transition to execute (without actually executing it, as this depends on subsequent stages) to the next regulation state (of the five regulation states described above) or to remain in the current state, depending on the transformer state, input state, and regulation state obtained in substage 2). Each state in the regulation process executes a switching sequence that activates or deactivates the secondary coils corresponding to one of the five regulation states. If the finite state machine decides to execute a transition to another regulation state, proceed to the next substage; otherwise, stage c) is repeated from the beginning upon overflow of TMR3. V. Review thirty consecutive samples to validate that the transformer's state change condition is stable and should be performed. If the thirty samples are not equal, the transformer state change is not performed, and step c) is repeated from the beginning upon overflow of TMR3. If the validation shows that the transformer state change condition is stable, meaning that the conditions generating the transition have remained long enough (during the thirty samples) to execute the regulation state change, proceed to the next step d); c) Execute Logic Level Change notification routines (Logic Level Change Detection - ISR) to detect zero crossings and phase-to-phase timing so that the PLC sends the signal to the power electronics at the optimal moment to turn on the SCRs or TRIACs that will activate the coils corresponding to the resulting regulation state. This is necessary to ensure that when the command to turn on the selected SCR or TRIAC is given, the previous SCR or TRIAC is already off. If it is not off, turning on the selected one would cause an excessive current draw, leading to electrical disturbances in the power supply and possible damage to the electrical components. Once a zero crossing has been detected, execute step e).It should be clarified that this routine can be executed in parallel to stage c) since the activation of the Logic Level Change notification routines occurs when a zero crossing is detected, which can happen at any time;. d) start timer TMR2; e) execute TMR2 transition interrupt routines to the next regulation state when TMR2 overflows at 5.58ms in accordance with the decision produced in step d), by transmitting a signal from the PLC to the power electronics to execute a specific switching sequence, which activates and / or deactivates digital output ports (GPIO) to handle the AC power semiconductor array (the SCRs or TRIACs) in order to activate or deactivate the secondary coils corresponding to the regulation state produced by the finite state machine; f) execute steps b) to f) until the voltage regulator is deactivated. Transformer status In stage c), it is indicated that the finite state machine determines the voltage conditioner regulation state. In accordance with the above, and referring to Figure 1, which shows a diagram of the autotransformer referencing each respective power semiconductor as TI, T2, T3, T4, and T5, and also referring to Figures 2 through 6, Table 1 summarizes the five states of the transformer bocnnn / 77n7 / e / YiAi that the control method can generate in the voltage conditioner and its output voltage / input voltage ratio per phase: bQcnnn / zznz / E / YiAi Transformer State Thyristors / Switches are On Coils Activated Vo / V Ratio Voltage Compensation Grade Name NA1 T1+T5 N2+N3 1.12 Severe Boost (++) NA2 T1+T3 N2+N3+N4 1.06 Soft Boost (+) NB T2+T3 N3+N4 1 Null (=) NC1 T2+T4 N3+N4+N5 0.94 Soft Buck (-) NC2 T4+T5 N4+N5 0.88 Severe Buck (--) Table 1: Autotransformer regulation status and voltage compensation level Entry status Likewise, the input state of the voltage conditioner will be defined below, which is determined by the classification of the input voltage range of the regulation funnel (Figure 7) and its relationship with the state of the transformer and the desired nominal output voltage in the equipment, in accordance with the following table: Numerical Equivalent Designation Lower Limit Upper Limit 7 CA (High Cut) 1.15Vnom Not Applicable 6 NC2 1.09Vnom 1.15Vnom 5 NC1 1.03Vnom 1.09Vnom 4 NB 0.97Vnom 1.03Vnom 3 NA2 0.97Vnom 0.91Vnom 2 NA1 0.91Vnom 0.85Vnom 1 CB (Low Cut) 0.85Vnom Not Applicable Table 2: Lower and upper limits of Vnom that delimit the input states. The entry state can also be expressed using the following statements: The High Cut input state will encompass all input voltages above 1.15*Vnom VCA> 1.15 * Vnom The NC2 input state comprises input voltages less than or equal to 1.15*Vnom and greater than or equal to 1.09Vnom. 1.09 * Vnom < VNC2< 1.15 * Vnom The NC1 input state will comprise input voltages less than or equal to 1.09 Vnom and greater than or equal to 1.03 Vnom. 1.03 * Vnom < VNCl< 1.09 * Vnom The NB input state will comprise input voltages less than or equal to 1.03Vnom and greater than or equal to 0.97Vnom. 0.97 * Vnom < VNB < 1.03 * Vnom The NA2 input state will comprise input voltages less than or equal to 0.97Vnom and greater than or equal to 0.91Vnom. 0.91 * Vnom < VWi42< 0.97 * Vnom The NA 1 input state will comprise input voltages less than or equal to 0.91 Vnom and greater than or equal to 0.85Vnom 0.91 * Vnom < < 0.97 * Vnom The Low Cut input state will comprise input voltages less than 0.85* Vnom VCB < 0.85 * Vnom The boundary between two adjacent input states is defined taking into account a hysteresis of 1V when making the transition from one state to another, in the finite state machine. The objective of the method is to carry out a discrete compensation of the input voltages per phase, which may be high or low with respect to the configured nominal voltage, by using the autotransformer in buck or boost mode, so that the nominal voltage at the output of the equipment remains the same as that which was configured. NA1 and NC2 are the states that make the most severe compensation, buck or boost; while the NA2 and NC1 states make a moderate compensation, buck or boost. Regulatory status bQcnnn / zznz / E / YiAi The input states and the transformer states can be represented in a regulation funnel, which is shown in Figure 7 and whose objective is to delimit the operating band of the equipment. bocnnn / 77n7 / e / YiAi In this regulation funnel, the five regulation (compensation) states generated by the method in the transformer can be identified: Regulation state Compensation degree NC2(-) Severe boost(++) NC1(-) Soft boost (+) NB(=) Zero(=) NA2(+) Soft buck(-) NA1 (++) Severe buck(-) Figure 7 shows that if any of the input voltages defined by the NC2 input state band (between 1.09 and 1.15) are multiplied by the regulation state defined by NC2(--) (-1.12), an output voltage range between 0.03% and -0.03% of the nominal voltage is obtained. Output voltage = Input state * Regulation state In other words, the regulation state allows us to compensate for the input state voltages to obtain an output voltage as close as possible to the configured nominal output voltage, with a tolerance of ±3% maximum error Figure 8 shows another representation of the regulation funnel. This figure illustrates that once the nominal operating voltage of the voltage conditioner is configured, it can receive an input voltage up to +15% above or -15% below the nominal voltage. Within this entire input voltage range, the voltage conditioner will be able to deliver an output between +2% and -2% of the nominal voltage configured for the equipment. The voltage conditioner is said to compensate discretely because it is defined or delimited by taps or steps that can be modeled through the finite state machine indicated in step b). Regulation state machine The state machine for regulating stage b) comprises a three-dimensional state transition matrix whose representation is shown in Figure 9: State transition matrix [transformer_state] [input_state] [regulation_state] Where each subscript represents: • Transformer state (current state): represents the state in which the regulating transformer is found. • Input_state: the input voltage seen by the equipment translated to one of the thresholds defined by the regulation funnel. • Regulation_state (regulation state): This can also be called the resulting state. This is the state that the regulating transformer should have based on its own current state and the input state. The purpose of the state transition matrix is ​​to evaluate regular expressions such as the following: *If the input state is very high and the transformer is in transparency (NB), then the regulating transformer must be brought to a severe buck state (NC2) to preserve the nominal output voltage. *If the input state is low and the transformer is in transparency (NB), then the regulating transformer must be brought to a moderate boost state (NA2) to maintain the nominal output voltage. Thus, the state machine to carry out regulation with a maximum deviation from the nominal voltage of ±3% for an input voltage range between ±15% is defined by the following state transition matrix: bQcnnn / zznz / E / YiAi 14 4 12 3 12 3 12 3 13 3 14 4 15 5 12 3 4 4 7 5 6 7 3 3 7 4 4 7 5 5 7 5 6 7 5 6 7 5 6 7 bocnnn / zznz / e / viAi Voltage Conditioner State Transition Matrix [i, j, k] [Transformer State], [Input State], [Regulation State] Or using the notation with the regulation taps: 1DLE CB NB NB NB NB NB CA ID1£ IDLE CB NA1 NA2 NB NC1 NC2 CA CB IDLE CB NA1 NA2 NA2 NA2 NA2 CA NA1 IDLE CB NA1 NA2 NB NB NB CA NA2 Status of IDLE CB NA2 NA2 NB NC1 NC1 CA NB transformer IDLE CB NB NB NB NC1 NC2 CA pin IDLE CB NC1 NC1 NC1 NC1 NC2 CA NQ IDLE CB NA1 NA2 NB NC1 NC2 CA Given the nature of the autotransformer, it is required that the transitions between the current state and the next state always be adjacent states; that is, if one is in state NB and wants to reach state NC2, one must first transition to NC1, and then to NC2. This is exemplified in the state transition matrix. The only states that allow a direct transition to the next state are the High (7) and Low (1) cuts. Therefore, the finite state machine will process the input voltage data as follows: Si el estado de entrada es Y el estado del transformador es: Entonces la transición será al estado de regulación: IDLE IDLE IDLE IDLE CB IDLE IDLE NA1 IDLE IDLE NA2 IDLE IDLE NB IDLE IDLE NC1 IDLE IDLE NC2 IDLE IDLE CA IDLE CB IDLE CB CB CB CB CB NA1 CB CB NA2 CB CB NB CB CB NC1 CB CB NC2 CB CB CA CB NA1 IDLE NB NA1 CB NA1 NA1 NA1 NA1 NA1 NA2 NA1 NA1 NB NA2 NA1 NC1 NB NA1 NC2 NC1 NA1 CA NA1 NA2 IDLE NB NA2 CB NA2 NA2 NA1 NA2 NA2 NA2 NA2 NA2 NB NA2 NA2 NC1 NB NA2 NC2 NC1 NA2 CA NA2 NB IDLE NB NB CB NB NB NA1 NA2 NB NA2 NB NB NB NB NB NC1 NB NB NC2 NC1 NB CA NB NC1 IDLE NB NC1 CB NC1 NC1 NA1 NA2 NC1 NA2 NB NC1 NB NC1 NC1 NC1 NC1 NC1 NC2 NC1 NC1 CA NC1 bQcnnn / zznz / E / YiAi NC2 IDLE NB NC2 CB NC2 NC2 NA1 NA2 NC2 NA2 NB NC2 NB NC1 NC2 NC1 NC2 NC2 NC2 NC2 NC2 CA NC2 CA IDLE CA CA CB CA CA NA1 CA CA NA2 CA CA NB CA CA NC1 CA CA NC2 CA CA CA CA IDLE es un estado indeterminado bQcnnn / zznz / E / YiAi As indicated above, Figure 9 shows a graphical representation of the state transition matrix machine, which is part of an infinite loop in the method, which is implemented in PLC Priorities of interruptions The TMR2, TMR3, and Logical Level Change Notification interrupts have the following priority assignment: Peripheral Associated Subroutines Priority Level TMR2 executes rCambio() Low Priority TMR3 obtain ParamElec() High Priority Logic Level Change Notification Detect Zero Crossing,timeBetweenPhases() Medium Priority The interrupt handling (ISR) shape is represented in Figure 10. From Figure 10 we can observe that the way in which the routines corresponding to each interrupt are activated are as follows: 1. TMR3 is initialized 2. Trigger: 100ms 3. Execute TMR3 interrupt routines 4. Trigger: Detects a zero crossing of voltage or current and asks if any phase needs a change of state; this change of state is defined by the finite state machine of the change review process. 5. If the conditions in point 4 are met (zero crossing detection + need for change) the TMR2 is started. 6. If TMR2 overflows 5.68s later, the transformer state change is executed. Interrupt Routine Logical Level Change Notification The Logic Level Change (ILC) notification routine, or zero-crossing detection, detects zero-crossing voltage (ZXV) and zero-crossing current (ZXI) signals from the sensors' energy measurement circuits to determine the autotransformer's operating conditions. By default, the ZXV signals have a 2.15 millisecond delay. Therefore, in this method, whenever a zero-crossing voltage signal is detected and a tap change is deemed necessary, if the tap change check routine is in place, timer (TMR2) is enabled. This timer overflows 5.68 milliseconds after the pulse is detected, turning off the current switch and allowing it to turn on at the next zero-crossing voltage signal.The Logical Level Change Notification ISR also coordinates the routines that calculate the phase shift time between lines, for calculating the phase angle and line-to-line voltage that can be displayed on the equipment's monitoring media. The elements used to switch the secondary coils to achieve boost or buck operation can be modeled as ideal switches. However, when using TRIACs or SCRs for switching, it's important to consider the phase shift between voltage and current that a load with capacitive or inductive components can generate when turning off the switches (see Figure 11). The current must reach zero before the switch is considered off. This is crucial for the autotransformer's turn-on sequence. If there isn't good synchronization or a sufficient phase shift between the turning off of one switch and the turning on of the next, harmful short-circuit currents can occur. In the absence of a load, an inductive load is assumed by default. That is why, when carrying out the routine to execute Change (transition to the next regulation state), for the activation of the next switch, a delay is also taken into account, which is calculated based on the power factor according to the following formula: delaymsec— 2.65[cos-1FP] Where FP represents the power factor measured by the energy measurement circuit. Figure 9 shows more clearly the switching sequence of the circuit breakers as a function of the power factor. It should finally be understood that the method for controlling a voltage conditioning unit of the present invention is not limited to the modality described above and that experts in the field will be trained, by the teachings established herein, to make changes to the method for controlling a voltage conditioning unit, the scope of which will be established exclusively by the following claims.

Claims

1. A method for controlling a three-phase voltage conditioner comprising: an autotransformer having a primary coil N1 and four secondary coils N2, N3, N4, and N5 respectively; power electronics for switching the electric current, comprising a plurality of TRIAOS or SCRs for activating the autotransformer coils; means for detecting operating conditions of the autotransformer, specifically measuring the effective voltage, current, power, energy, and power factor; and digital control electronics connected to the power electronics and the means for detecting operating conditions of the autotransformer via a UART-type communication interface, wherein the digital control electronics comprises a microcontroller (PLC). The method controls the voltage conditioner in such a way as to achieve five levels of regulation with respect to the input voltage.where each level of regulation is achieved by connecting two or more secondary coils N1, N2, N3 or N4, which form a single coil, called combined coils which are: NA1 which is activated when the means for detecting operating conditions detect an input voltage called “very low” according to a predefined parameter, NA2 which is activated when the means for detecting operating conditions detect an input voltage “low”, which is greater than the “very low” voltage, NB which is activated when the means for detecting operating conditions detect an input voltage “acceptable”, which is greater than the “low” voltage, NC1 which is activated when the means for detecting operating conditions detect an input voltage “high”, which is greater than the “acceptable” input voltage,and NC2, which is activated when the means for detecting operating conditions detect a “very high” input voltage that is greater than the “high” input voltage; bocnnn / 77n7 / B / YiAi wherein the very low, low, acceptable, high, and very high voltage ranges are predefined in the voltage conditioner and are not limited to specific ranges; wherein the method for controlling a voltage conditioner is characterized by comprising the following steps: a) initializing timers TMR2 and TMR3 to zero and configuring the overflow times. In a preferred embodiment, TMR2 overflows at 5.58 ms and TMR3 overflows at 100 ms as described above; b) initiating the execution of an infinite state machine comprising the following steps:

1. Initializing TMR3, 2. Execute the following TMR3 interrupt routines when TMR3 overflows at 100ms, for each phase: I. Obtain information from three electrical sensors to obtain the electrical parameters of the input and output through the UART communication interface. The information obtained is: voltage, current, power, energy, and power factor; II. Classify the transformer state, the input state, and the regulation state based on the information obtained from step I. The method for classifying these states will be indicated later; III. Check the consistency between the input state, the transformer state, and the output state of each phase in order to validate the correct operation of the regulation. If there is no consistency, it is determined that the equipment is in an internal error state, and the equipment is switched to a transparency state where the input equals the output.The agreement check involves reading the input voltage and reading the output voltage and comparing it with the theoretical value that would correspond to the output. If the output voltage value corresponds to the input voltage multiplied by the factor of the present regulation state, then there is agreement. But if the output value does not correspond to the calculated value, then there is no agreement; IV.Using the information obtained from points I and II, process a finite state machine (FSM) to determine whether to execute a transition and which transition to execute (without actually executing it, as this depends on subsequent stages) to the next regulation state (of the five regulation states described above) or to remain in the current state, depending on the transformer state, input state, and regulation state obtained in substage 2. Each state in the regulation process executes a switching sequence that activates or deactivates the secondary coils corresponding to one of the five regulation states. If the finite state machine decides to execute a transition to another regulation state, proceed to the next substage; otherwise, stage c) is repeated from the beginning upon overflow of FSM3; V.Review thirty consecutive samples to validate that the transformer's state change condition is stable and should be performed. If the thirty samples are not equal, the transformer state change is not performed, and step c) is repeated from the beginning upon overflow of TMR3. If the validation shows that the transformer's state change condition is stable, meaning that the conditions generating the transition have remained long enough (during the thirty samples) to execute the regulation state change, proceed to the next step d); c) execute Logic Level Change notification routines (Logic Level Change Detection - ISR) to detect zero crossings and phase intervals so that the PLC sends the signal to the power electronics at the optimal moment to activate the SCRs or TRIACs that will activate the coils corresponding to the resulting regulation state.This is necessary to ensure that when the command to turn on the SCR or TRIAC to be activated is given, the previous SCR or TRIAC is already off. If it is not off, turning on the selected one would cause an excessive current draw, leading to electrical disturbances in the power supply and possible damage to the electrical components. Once a zero crossing is detected, execute step e). It should be noted that this routine can be executed in parallel with step c) since the activation of the Logic Level Change notification routines occurs when a zero crossing is detected, which can happen at any time; d) start timer TMR2; e) execute TMR2 interrupt routines for transitioning to the next regulation state when TMR2 overflows at 5.58ms in accordance with the decision produced in step d), by transmitting a signal from the PLC to the power electronics to execute a specific switching sequence, which activates and / or deactivates digital output ports (GPIO) to handle the set of AC power semiconductors (the SCRs or TRIACs) in order to activate or deactivate the secondary coils corresponding to the regulation state produced by the finite state machine; f) execute steps b) to f) until the voltage regulator is deactivated.

2. A method for controlling a three-phase voltage conditioner according to claim 1, wherein the method considers that the autotransformer has the following input states: bocnnn / 77n7 / e / YiAi Numerical Equivalent Designation Lower Limit Upper Limit 7 CA (High Cutoff) 1.15Vnom Not Applicable 6 NC2 1.09Vnom 1.15Vnom 5 NC1 l.OSVnom 1.09Vnom 4 NB 0.97Vnom 1.03Vnom 3 NA2 0.97Vnom 0.91Vnom 2 NA1 0.91Vnom 0.85Vnom | 1 | CB (Low Cut) | 0.85Vnom | Not Applicable |.

3. A method for controlling a three-phase voltage conditioner according to claim 1, wherein the autotransformer has five switches T1, T2, T3, T4, and T5, and wherein the method considers the transformer states to be those defined in the following table: bocnnn / 77n7 / e / YiAi Transformer State Switches On Coils Activated Vo / Vi Ratio Voltage Compensation Degree Name NA1 TI + T5 N2+N3 1.12 Severe Boost (++) NA2 T1+ T3 N2+N3+N4 1.06 Mild Boost (+) NB T2+T3 N3+N4 1 Zero (=) NC1 T2+T4 N3+N4+N5 0.94 Mild Decrease (-) NC2 T4+T5 N4+N5 0.88 Severe Decrease (-) 4. A method for controlling a three-phase voltage conditioner according to any of the preceding claims, wherein the autotransformer has the following regulation states: Regulation State Degree of Compensation NC2 Severe Boost (++) NC1 Soft Boost (+) NB Zero (=) NA2 Soft Decrease (-) NA1 Severe Decrease (--) 5. A method for controlling a three-phase voltage conditioner according to any of the preceding claims, wherein the finite state machine makes the decision to execute a transition to the following regulating state according to the following table: If the input state is and the transformer state is: Then the transition will be to the regulating state: IDLE IDLE IDLE IDLE CB IDLE IDLE NA1 IDLE IDLE NA2 IDLE IDLE NB IDLE IDLE NC1 IDLE IDLE NC2 IDLE IDLE CA IDLE CB IDLE CB CB CB CB CB NA1 CB CB NA2 CB CB NB CB CB NC1 CB CB NC2 CB CB CA CB NA1 IDLE NB NA1 CB NA1 NA1 NA1 NA1 NA1 NA2 NA1 NA1 NB NA2 NA1 NC1 NB NA1 NC2 NC1 NA1 CA NA1 NA2 IDLE NB NA2 CB NA2 NA2 NA1 NA2 NA2 NA2 NA2 NA2 NA2 NB NA2 NA2 NC1 NB NA2 NC2 NC1 NA2 CA NA2 NB IDLE NB NB CB NB NB NA1 NA2 NB NA2 NB NB NB NB NB NC1 NB NB NC2 NC1 NB CA NB NC1 IDLE NB bQcnnn / zznz / E / YiAi NC1 CB NC1 NC1 NA1 NA2 NC1 NA2 NB NC1 NB NC1 NC1 NC1 NC1 NC1 NC2 NC1 NC1 CA NC1 NC2 IDLE NB NC2 CB NC2 NC2NA1 NA2 NC2 NA2 NB NC2 NB NC1 NC2 NC1 NC2 NC2 NC2 NC2 NC2 CA NC2 CA IDLE CA CA CB CA CA NA1 CA CA NA2 CA CA CA NB CA CA NC1 CA CA NC2 CA CA CA CA bocnnn / 77n7 / e / YiAi 6. A method for controlling a three-phase voltage conditioner according to claim 1, wherein in the transition to the next regulation state, for the switching on of the next switch, a delay is also taken into account which is calculated based on the power factor according to the following formula: delaymsec = 2.65[cos-1FP] Where FP represents the power factor measured by the energy measurement circuit.

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