A primary and secondary fused complete on-line circuit breaker capacitor power taking circuit and adjusting method

Abstract

The application belongs to the technical field of electric power, and particularly relates to a primary and secondary fusion complete set of pole-mounted circuit breaker capacitor power taking circuit and a regulating method. The power taking circuit comprises a plurality of capacitor voltage division units connected in series between a high-voltage end and a primary side of a transformer. A protection circuit is further connected to the primary side of the transformer. The protection circuit comprises a bootstrap protection branch connected in parallel to the primary side. The bootstrap protection branch comprises a second resistor and a bootstrap protection switch connected in series. The other end of the primary side of the transformer not connected to the capacitor voltage division unit is grounded through a primary side capacitor. The primary side capacitor is connected in parallel to a high-voltage bootstrap protection module. An output end of the high-voltage bootstrap protection module is connected to a control end of the bootstrap protection switch K2. The protection circuit can short-circuit the primary side of the transformer in the case of overvoltage and lightning strike, thereby avoiding the burning of the transformer and the load connected to the secondary side. The short-circuit capacitor voltage division unit can be flexibly adjusted to adapt to different loads.

Description

Technical Field

[0001] This invention belongs to the field of power technology and relates to high-voltage power grid power extraction circuits, specifically to a primary and secondary integrated pole-mounted circuit breaker capacitor power extraction circuit and its adjustment method. Background Technology

[0002] A primary and secondary integrated pole-mounted circuit breaker refers to an integrated power distribution switchgear that deeply integrates and collaboratively designs primary equipment such as the circuit breaker body and instrument transformers with secondary equipment such as distribution automation terminals, protection devices, and communication modules to achieve functional integration. Existing technologies for drawing power from primary and secondary integrated pole-mounted circuit breakers mainly include voltage transformer power drawing and capacitor voltage divider power drawing. Capacitor voltage divider power drawing involves connecting a power module between the live wire and ground, relying on capacitive reactance for current limiting and a small transformer for isolation, outputting isolated low-voltage power from the low-voltage side of the transformer. Capacitor voltage divider power drawing has advantages such as small size, low cost, easy installation, and high stability. However, it is easily burned out under overvoltage and lightning strike conditions. Furthermore, when the output load increases, the current cannot be adjusted because the capacitor in the power drawing circuit cannot be adjusted, making the existing capacitor voltage divider power drawing circuit unable to adaptively adjust with the load. Summary of the Invention

[0003] In view of the technical defects of the prior art, the present invention discloses a capacitor power supply circuit and adjustment method for a primary and secondary integrated pole-mounted circuit breaker.

[0004] The primary and secondary integrated pole-mounted circuit breaker capacitor power supply circuit of the present invention includes multiple capacitor voltage divider units connected in series between the high-voltage end and the primary side of the transformer. Each capacitor voltage divider unit includes a voltage divider capacitor, and the voltage divider capacitors of all capacitor voltage divider units are connected in series between the high-voltage end and the primary side of the transformer.

[0005] A protection circuit is also connected to the primary side of the transformer. The protection circuit includes a bootstrap protection branch connected in parallel with the primary side. The bootstrap protection branch includes a second resistor and a bootstrap protection switch connected in series. The other end of the primary side of the transformer that is not connected to the capacitor voltage divider unit is grounded through the primary side capacitor. A high-voltage bootstrap protection module is connected in parallel with the primary side capacitor. The output terminal of the high-voltage bootstrap protection module HVP is connected to the control terminal of the bootstrap protection switch. The high-voltage bootstrap protection module is configured to control the bootstrap protection switch to close when the voltage of the primary side capacitor increases to a set voltage threshold.

[0006] Preferably, a third resistor, which is a varistor, is connected between one end of the primary side of the transformer connected to the capacitor voltage divider unit and ground.

[0007] Preferably, the bootstrap protection switch is a relay, and the high-voltage bootstrap protection module includes a full-bridge rectifier circuit connected in parallel with the primary capacitor. The input terminals of the full-bridge rectifier circuit are respectively connected to the two ends of the primary capacitor. The high-voltage bootstrap protection module also includes a switching transistor. The switching transistor and the relay coil are connected in series and then in parallel with the voltage stabilizing capacitor. The control terminal of the switching transistor is connected to the output terminal of the primary capacitor voltage detection circuit.

[0008] Preferably, a transient breakdown diode is connected in parallel across the primary capacitor.

[0009] Preferably, among the plurality of capacitor voltage divider units, at least one short-circuitable capacitor voltage divider unit CH2 is included, and a low-voltage output regulator is connected to the secondary side of the transformer;

[0010] The low-voltage output regulator is configured to: detect the secondary power, and when the difference between the secondary power and the current rated power is less than a set power margin threshold M1, output a control signal to short-circuit the voltage divider capacitor of at least one short-circuitable capacitor divider unit to adjust the current rated power until the difference between the secondary power and the current rated power is greater than the set power margin threshold.

[0011] Preferably, the low-voltage output regulator is configured to restore the voltage divider capacitor to the circuit when the difference between the secondary power and the current rated power is greater than a set power margin callback threshold, and at least one short-circuitable capacitor divider unit's voltage divider capacitor is short-circuited, until the difference between the secondary power and the current rated power is less than the set power margin callback threshold.

[0012] Preferably, the short-circuitable capacitor voltage divider unit includes a voltage divider capacitor and a capacitor short-circuit switch connected in parallel with the voltage divider capacitor.

[0013] Preferably, the capacitor short-circuit switch is a high-voltage optocoupler, and the control terminal of the capacitor short-circuit switch is connected to the low-voltage output regulator.

[0014] This invention also discloses a method for adjusting the capacitor power supply circuit of a primary and secondary integrated pole-mounted circuit breaker, based on the above-mentioned capacitor power supply circuit of the primary and secondary integrated pole-mounted circuit breaker, comprising the following steps:

[0015] Step 1. Set the power margin threshold M1 and the rated power of different voltage divider capacitors when they are short-circuited;

[0016] Step 2. Detect the secondary power. When the difference between the secondary power and the current rated power is less than the set power margin threshold M1, output a control signal to short-circuit the voltage divider capacitor of at least one short-circuitable capacitor divider unit to adjust the current rated power until the difference between the secondary power and the current rated power is greater than the set power margin threshold.

[0017] Preferably, step 2 further includes: when the difference between the secondary power and the current rated power is greater than the set power margin callback threshold, and the voltage divider capacitor of at least one short-circuitable capacitor voltage divider unit is short-circuited, the voltage divider capacitor is restored to the circuit until the difference between the secondary power and the current rated power is less than the set power margin callback threshold.

[0018] The primary and secondary integrated pole-mounted circuit breaker capacitor power supply circuit and adjustment method described in this invention, on the one hand, utilizes a capacitor voltage divider unit to distribute voltage. Using conventional high-voltage capacitors (1KV to 5KV) as voltage divider capacitors can meet the capacitor withstand voltage requirements of high-voltage terminals (commonly 10KV / 35KV), not only broadening the range of capacitor selection but also helping to control capacitor usage costs. Simultaneously, multiple series-connected voltage divider capacitors can control the transformer primary-side input voltage / power, matching the transformer's rated voltage / power requirements. On the other hand, when a single voltage divider capacitor breaks down due to various possibilities, the remaining voltage divider capacitors continue to distribute the voltage (in further applications, based on the existing output power, the voltage divider capacitors that can be short-circuited can be controlled to reduce the voltage borne by a single capacitor, thereby enhancing the reliability of power supply and avoiding a complete collapse of the power supply due to the failure of a few capacitors). This effectively reduces the risk of instantaneous short circuits and other faults in the line (in specific applications, a voltage divider capacitor withstand voltage redundancy design is adopted to improve the reliability of the power supply circuit and the operating line). Furthermore, for protection... Since the voltage between the primary side of the transformer and its capacitor is a low value obtained through voltage division, the bootstrap protection switch is triggered by detecting the voltage value of the primary capacitor. This effectively avoids problems such as the voltage of the primary capacitor fluctuating directly with the voltage at the high-voltage end, which could easily cause the protection circuit to malfunction or fail to be triggered due to the voltage protection threshold (compared to the voltage protection threshold configured directly for the high-voltage bootstrap protection module to adapt to high-voltage fluctuations without a capacitor voltage divider unit). On the other hand, multiple series-connected voltage divider capacitors can accurately match the capacitive reactance of the transformer's primary side, thus improving the stability of the power supply voltage. Furthermore, by setting up a protection circuit and based on the detection results of the primary capacitor voltage, the transformer's primary side can be short-circuited in the event of overvoltage or lightning strikes. By connecting a varistor in parallel on the transformer's primary side and a suppressor inductor in series at the beginning of the power supply circuit, the high-voltage capacitor can be protected from direct burnout during lightning strikes, and the insulation breakdown of the transformer's primary side can be avoided. This also prevents the load connected to the transformer and secondary side from burning out. By adding a short-circuitable capacitor voltage divider unit, the rated power of the secondary side can be flexibly adjusted to adapt to different loads.

[0019] In summary, this solution provides a power supply scheme for a primary and secondary integrated pole-mounted circuit breaker that offers high reliability, high power supply reliability, and low engineering implementation difficulty. Attached Figure Description

[0020] Figure 1This is a schematic diagram of a specific embodiment of the capacitor power extraction circuit of the primary and secondary integrated pole-mounted circuit breaker described in this invention;

[0021] Figure 2 This is a schematic diagram of a specific embodiment of the capacitor voltage divider unit described in this invention;

[0022] Figure 3 This is a schematic diagram of a specific embodiment of the short-circuitable capacitor voltage divider unit described in this invention;

[0023] Figure 4 This is a schematic diagram of a specific embodiment of the high-voltage bootstrap protection module described in this invention;

[0024] Figure 5 This is a state simulation diagram illustrating a specific application embodiment of the capacitor-driven power supply circuit of the integrated primary and secondary pole-mounted circuit breaker described in this invention. Detailed Implementation

[0025] To more intuitively and clearly describe the specific details of the technical solution of the present invention, a detailed description will be provided below in conjunction with specific embodiments and example drawings.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] The primary and secondary integrated pole-mounted circuit breaker capacitor power supply circuit of the present invention, such as... Figure 1 As shown, it includes multiple capacitor voltage divider units connected in series between the high-voltage terminal HV and the primary side of the transformer T. Each capacitor voltage divider unit includes a voltage divider capacitor C1, and the voltage divider capacitors of all capacitor voltage divider units are connected in series between the high-voltage terminal HV and the primary side of the transformer T.

[0028] To improve the primary-side protection capability, a protection circuit is also connected to the primary side. The protection circuit includes a bootstrap protection branch connected in parallel with the primary side. The bootstrap protection branch includes a second resistor R2 connected in series and a bootstrap protection switch K2. The other end of the transformer primary side that is not connected to the capacitor voltage divider unit is grounded through the primary-side capacitor C3. The primary-side capacitor C3 is connected in parallel with a high-voltage bootstrap protection module. The output terminal of the high-voltage bootstrap protection module HVP is connected to the control terminal of the bootstrap protection switch K2. Its function is to control the bootstrap protection switch K2 to close when the voltage of the primary-side capacitor C3 increases to a set voltage threshold.

[0029] When the voltage at the high-voltage end HV continuously increases, causing the primary voltage of the transformer to become excessive, the AC voltage on the primary capacitor C3 increases to reach the set voltage threshold, causing the bootstrap protection switch K2 to close. This effectively short-circuits the primary side of the transformer, and the transformer stops working. Since the short-circuited primary side no longer bears voltage, the overall impedance of the inductor in the main circuit increases slightly after the short circuit. At this time, after the primary side is short-circuited, the voltage shared by the primary capacitor C3 will not decrease, but will increase slightly or remain the same, causing the transformer to remain in the primary short-circuit state and not work until the voltage at the high-voltage end HV decreases significantly and the voltage shared by the primary capacitor C3 decreases below the set voltage threshold. Only then will the bootstrap protection switch K2 open again, and the transformer T resumes operation.

[0030] like Figure 5 A simulation diagram of the above state is given. The horizontal axis represents the high-voltage end voltage in kilovolts. The horizontal axis does not change linearly, but first rises to a peak value of 13kV and then decreases.

[0031] For ease of observation, Figure 5 The CCP has combined three curves: the primary voltage VT1 of the transformer, the voltage VC3 across the primary capacitor C3, and the current IC3 across the primary capacitor C3. For VT1, the vertical axis is... Figure 5 On the right, for VC3 and IC3, the vertical axis is... Figure 5 On the left, the unit on the VC3 curve is volt, and the unit on the IC3 curve is milliampere.

[0032] When the high-voltage side voltage increases to approximately 11.4 kV, the transformer primary voltage VT1 increases to 1650V. At this point, the bootstrap protection switch K2 closes, effectively short-circuiting the transformer primary side. The transformer stops working, and the primary voltage drops rapidly to zero. As the high-voltage side voltage continues to decrease, the voltage shared by the primary capacitor C3 drops below the set voltage threshold, at which point the bootstrap protection switch K2 will open again. The transformer T resumes operation when the voltage on the horizontal axis is approximately 10.2 kV.

[0033] Figure 5 The reason for the inconsistent voltage inflection points on the primary side of the transformer is the use of hysteresis design in the high-voltage bootstrap protection module, for example, by utilizing... Figure 4 In the specific circuit shown, the rail-to-rail comparator CP uses a hysteresis comparator, which makes the threshold voltage at the time of opening different from the threshold voltage at the time of closing when the bootstrap protection switch is closed and then opened. This causes the voltage inflection point of the transformer primary side to be inconsistent. The hysteresis design prevents the high-voltage bootstrap protection module from causing the bootstrap protection switch K2 to switch frequently, resulting in repeated voltage fluctuations and improving the reliability of the protection circuit.

[0034] from Figure 5It can be seen that the voltage VC3 and current IC3 on the primary capacitor C3 basically change with the high-voltage side voltage on the horizontal axis. When the bootstrap protection switch is closed, the transformer is short-circuited, and the impedance canceled by the original transformer inductance and primary capacitor disappears, causing the overall impedance to rise. This causes the current IC3 on the primary capacitor C3 to decrease briefly, and the voltage VC3 on the primary capacitor C3 also decreases accordingly. However, it quickly follows the high-voltage side voltage and continues to rise. After the high-voltage side voltage begins to fall, it also decreases. After the bootstrap protection switch is reopened, the transformer is reconnected to the circuit, and the overall impedance decreases. This causes the current IC3 on the primary capacitor C3 to increase briefly, and the voltage VC3 on the primary capacitor C3 also increases accordingly. However, it quickly follows the high-voltage side voltage and continues to fall.

[0035] Figure 1 In the specific embodiment shown, a third resistor R3 is connected between one end of the capacitor voltage divider unit on the primary side of transformer T and ground. The third resistor R3 is a varistor, which can be a varistor with a varistor voltage of 3500V and a surge current of 10kA (maximum leakage current ≤50μA). The third resistor R3 is used to deal with short-term transient overvoltages (such as lightning surges and grid operation overvoltages) that may occur on the primary side of the transformer. Specifically, when the voltage on the varistor exceeds the varistor voltage of the resistor itself, the resistance value drops rapidly in an avalanche-like manner. When the voltage on the primary side of the transformer rises and the voltage on the third resistor R3 reaches the varistor voltage, the resistance value drops rapidly, releasing most of the current from the third resistor R3. The third resistor R3 is used to deal with the situation of short-term transient abnormal increase in the primary voltage of the transformer.

[0036] The bootstrap protection switch K2 can be a high-voltage switching device such as a relay, a thyristor, or a reed switch, for example... Figure 4 The diagram illustrates a specific implementation of the high-voltage bootstrap protection module HVP. The bootstrap protection switch K2 is a relay. The high-voltage bootstrap protection module HVP includes a full-bridge rectifier circuit MD connected in parallel with the primary capacitor C3 (within the dashed box). The two input terminals of the full-bridge rectifier circuit MD are respectively connected to the two ends of the primary capacitor C3. Its two output terminals are used to output the rectified DC voltage, which is connected in parallel with the voltage-stabilizing capacitor C2 to convert the AC voltage across the primary capacitor C3 into a DC voltage. This charges the voltage-stabilizing capacitor C2 in the high-voltage bootstrap protection module HVP and provides operating power to devices such as the rail-to-rail comparator CP and the switching transistor MK. The high-voltage bootstrap protection module HVP also includes a switching transistor MK. One end of the switching transistor MK is connected to the relay coil DL, and the other end of the switching transistor MK and the relay coil DL, which are not connected to each other, is respectively connected to the two ends of the voltage-stabilizing capacitor C2. The control terminal of the switching transistor MK is connected to the output terminal of the primary capacitor voltage detection circuit.

[0037] The rail-to-rail comparator CP samples the voltage across the stabilizing capacitor C2 and compares it with a reference voltage. When the sampled voltage is higher than the reference voltage, the switching transistor MK is turned on, and the disconnection threshold voltage of the rail-to-rail comparator CP is lowered (hysteresis comparator function to avoid jitter). Once the sampled voltage is lower than the disconnection threshold voltage, the switching transistor MK is turned off, and the comparator threshold voltage is restored to its initial setting. This solution uses the hysteresis comparator function to precisely control the switching on and off of the high-voltage bootstrap protection module, eliminating protection circuit malfunctions and frequent switching problems, improving the reliability of transformer primary-side short-circuit protection under overvoltage conditions; and strengthening the hysteresis design and anti-jitter, and resisting power grid fluctuations.

[0038] The working principle of the high-voltage bootstrap protection module is as follows: The AC voltage on the primary capacitor C3 is chopped by the full-bridge rectifier circuit MD to form a DC half-wave, and then filtered by the voltage regulator capacitor C2 to form a stable DC voltage VC2. The voltage VC2 of the voltage regulator capacitor C2 is proportional to the AC voltage on the primary capacitor C3. The rail-to-rail comparator CP uses the voltage on the voltage regulator capacitor C2 as its power supply. (When the high-voltage terminal HV applies voltage to the primary capacitor C3 through the capacitor voltage divider unit, the AC voltage of the primary capacitor C3 is rectified by the full-bridge rectifier circuit MD and initially charges the voltage regulator capacitor C2. When the voltage of the primary capacitor C3 reaches the set voltage value (depending on the specific configuration, such as 50V), the voltage regulator capacitor C2 can store enough voltage to supply the rail-to-rail comparator CP.) Upon startup, the voltage regulator capacitor C2 charges extremely quickly (usually less than 50ms), ensuring that the protection circuit does not experience a power supply failure when protection is required. If the voltage of the primary capacitor C3 is below 50V, the high-voltage bootstrap protection module is in standby mode (at which point the transformer primary voltage is low and the protection function does not need to be activated). Simultaneously, the voltage of VC2 on the voltage regulator capacitor C2 is detected. When the voltage of VC2 exceeds the comparison voltage of the rail-to-rail comparator CP, the control signal output by the comparator is reversed, causing the previously disconnected switch to close, energizing the relay coil DL, and closing the relay acting as the bootstrap protection switch K2, thus short-circuiting the transformer primary side.

[0039] To limit short-circuit current and protect the contacts of the bootstrap protection switch K2, a second resistor R2 is connected in series with the bootstrap protection switch K2. Figure 4 In the specific embodiment shown, a transient breakdown diode (TVS) is connected in parallel across the primary capacitor C3. This TVS can short-circuit the primary capacitor C3 when the voltage of the primary capacitor C3 rises abnormally, thus preventing the primary capacitor C3 from being broken down.

[0040] By setting up a protection circuit, the primary side of the transformer can be short-circuited in the event of overvoltage or lightning strikes, thus preventing the transformer and the load connected to the secondary side from burning out.

[0041] In a preferred embodiment, the plurality of capacitor voltage divider units include several conventional capacitor voltage divider units CH1 and at least one short-circuitable capacitor voltage divider unit CH2. A low-voltage output regulator (LVC) is connected to the secondary side of the transformer. The LVC is configured to: detect the secondary power; when the difference between the secondary power and the current rated power is less than a set power margin threshold M1, output a control signal to short-circuit the voltage divider capacitor C1 of at least one short-circuitable capacitor voltage divider unit to adjust the current rated power until the difference between the secondary power and the current rated power is greater than the set power margin threshold.

[0042] In one specific embodiment, a capacitor voltage divider unit is used to achieve high voltage step-by-step voltage division. Multiple capacitors connected in series can distribute the high voltage. Under normal operation, each capacitor voltage divider unit actually withstands a voltage of approximately 100-300V. For example, when the high voltage terminal voltage is 5000V, 20-30 capacitor voltage divider units may be needed for voltage division. The value of each voltage divider capacitor C1 is between 100nF and 300nF. (In specific applications, those skilled in the art can select the specific number and capacitance range of capacitor voltage divider units within the above range according to the specific high voltage terminal voltage and the specific capacitor selection. Other numbers and capacitance values ​​of capacitor voltage divider units can also be selected. Preferably, to avoid the smaller capacitance value capacitor being broken down due to excessive voltage due to uneven capacitance values ​​in multiple capacitor voltage divider units connected in series, and subsequently causing other capacitors to be cascaded down, it is preferable to use capacitors with equal capacitance values ​​in each capacitor voltage divider unit (e.g., all using capacitors with a capacitance value of 200nF)).

[0043] A specific implementation of the conventional capacitor voltage divider unit CH1 is as follows: Figure 2 As shown, it includes a voltage divider capacitor C1 and a shunt branch connected in parallel with the voltage divider capacitor C1. The shunt branch includes a transient voltage suppressor diode (TVS). The transient voltage suppressor diode does not conduct under normal use, but it can conduct momentarily when the voltage divider capacitor is subjected to high voltage. In order to limit the current during momentary conduction, a first resistor R1 for current limiting can be connected in series in the shunt branch.

[0044] During long-term use, the distance between the capacitor plates of a voltage divider capacitor is likely to gradually increase, resulting in a decrease in capacitance and an increase in capacitive reactance. When the voltage at the high-voltage end and the transformer rises abnormally due to grid fluctuations or lightning strikes, the voltage between the capacitor plates increases. To avoid capacitor breakdown, the high voltage is discharged through a shunt branch.

[0045] like Figure 3The diagram illustrates a specific implementation of the short-circuitable capacitor voltage divider unit CH2. The difference from the conventional capacitor voltage divider unit CH1 is that, in addition to including a voltage divider capacitor C1 and a shunt branch connected in parallel with C1, it also includes a capacitor short-circuit switch K1 connected in parallel with the voltage divider capacitor. Since the absolute voltage values ​​of each capacitor voltage divider unit may be inconsistent, the capacitor short-circuit switch K1 uses a high-voltage optocoupler. The optical signal is output from the low-voltage output controller (LVC). The LVC detects the power on the secondary side of the transformer, i.e., the load side. When the difference between the secondary side power and the current rated power is less than the set power margin threshold M1, the output signal causes the capacitor short-circuit switch K1 of one or more short-circuitable capacitor voltage divider units to close, thus short-circuiting the voltage divider capacitor C1 of that short-circuitable capacitor voltage divider unit.

[0046] When the voltage divider capacitor C1 is short-circuited, the capacitance connected in series from the high-voltage end to the primary side of the transformer decreases, the absolute capacitance increases, and the capacitive reactance decreases. This leads to an increase in the primary current and primary power. When the transformer operates in its optimal operating region, the rated power of the secondary side also increases. Specifically, when the primary input power reaches 70% to 90% of the transformer's rated input power (rated capacity), the transformer core flux tends to saturate (the transformer's volume and transmission efficiency reach their optimal range (optimal operating region)). The secondary output power then exhibits an approximately linear relationship with the primary input power. Under normal high-voltage conditions, to ensure the transformer operates stably within its optimal operating range (70% to 90% of the rated input power), the preferred configuration in practical applications is as follows: the total capacitive reactance of the series-connected capacitor voltage divider unit, the number of turns in the transformer primary winding, and the core material are designed to be matched. This ensures that under common normal operating conditions such as high-voltage 10KV / 35KV, the primary input power always falls within this range. If significant fluctuations in the grid voltage cause the transformer's primary input power to deviate from the optimal operating range, resulting in fluctuations in the ratio of secondary power to primary input power and a mismatch between secondary power and the current rated power, the low-voltage output controller (LVC) adjusts the primary input power by regulating the short-circuitable capacitor voltage divider unit. This returns the transformer to its optimal operating range and matches the current rated power with the power required by the load, achieving reliable power supply.

[0047] More specifically, the transformer is configured such that when the secondary power matches the current rated power (the difference between the secondary power and the current rated power is between the power margin threshold M1 and the power margin callback threshold), the primary input power is in the transformer's optimal operating range (e.g., 70% to 90% of the transformer's rated input power). The mechanism by which the low-voltage output regulator (LVC) adjusts the short-circuit capacitor divider unit is as follows: when the difference between the monitored secondary power (the actual power used by the load connected to the transformer secondary) and the current rated power (the maximum power that the transformer secondary can currently output) is less than the set power... When the margin threshold M1 is reached, the adjustment action of the short-circuitable capacitor divider unit is not immediately executed. Instead, a delay timer is started (the delay time is set to be more than 50ms). Preferably, the system is configured with a settable delay time range, such as 50ms to 200ms. The maintenance personnel can set the specific time according to the actual grid fluctuation characteristics and through the external interface of LVC. If the difference between the secondary power and the current rated power is still less than the set power margin threshold M1 after the delay ends, or the primary input power has not yet recovered to the rated input power range corresponding to the optimal operating area, then LVC will perform an adjustment action. By short-circuiting or restoring the voltage divider capacitor of the short-circuitable capacitor divider unit, the primary input power is adjusted so that the secondary power of the transformer increases to meet the requirements, or the transformer returns to the optimal operating area to achieve reliable power supply. In practical applications, if a mismatch occurs between the secondary power and the transformer operating in its optimal operating range, the difference between the secondary power and the current rated power serves as the fundamental objective of the LVC's adjustment actions. The adjustment actions involved in restoring the primary input power to the rated input power range corresponding to the optimal operating range should be carried out on the premise of satisfying this fundamental objective.

[0048] The above mechanism aims to address the following issues: During grid operation, there may be transient voltage fluctuations (such as lightning transients, line closing impacts, etc.). The duration of these transient fluctuations is usually no more than 50ms. Using the above delay configuration method can filter out false power deviation signals caused by such transient interference, avoiding frequent triggering of short-circuit capacitor voltage divider units, which could accelerate the aging of corresponding switches, reduce overall circuit reliability, and affect power supply stability (e.g., when the grid operates with high-frequency voltage fluctuations of ±5%, LVC real-time regulation may experience over-regulation, reverse regulation, and further over-regulation oscillations, potentially even preventing normal power supply to the load in the power supply circuit). In the power supply circuit load, components such as communication modules are sensitive electronic devices with high requirements for power supply voltage stability. Ideally, an energy storage unit for storing the extracted power can be configured on the power supply circuit, or a separate energy storage unit can be set for the power-consuming modules on the circuit breaker to solve short-term power supply gaps and power supply deviation problems. Simultaneously, a maximum delay of 200ms will not affect the normal operation of the transformer: the transformer may deviate from its optimal operating range for short periods from 50ms to 200ms. It will not lead to a significant increase in core hysteresis loss, and based on existing technology, it will not have a substantial impact on the stability of the secondary load power supply. This implementation method takes into account both the anti-interference capability of the system / circuit and the reliability of power supply.

[0049] In the above implementation methods, the transformer operates in the optimal operating range, and the actual calibrated transformer has a safe, economical, and efficient load level. To achieve this goal and make the secondary power match the current rated power, the method of detecting the primary side parameters can also be used. The method of detecting the secondary side power based on the low-voltage output controller (LVC) proposed above is a method that directly correlates the secondary side power with the current rated power matching relationship. If the detected primary side input power deviates from the rated input power range corresponding to the optimal operating range (such as below 50% or above 95%), and the secondary side power is further adjusted through the short-circuit capacitor voltage divider unit CH2 to restore the transformer to operate in the optimal operating range or approach the optimal operating range, it should also be considered an equivalent scheme to detecting the secondary side power.

[0050] As the primary power increases when the transformer is operating in or close to its optimal operating range, the rated power of the secondary output will also increase accordingly. The low-voltage output controller has pre-stored the rated power values ​​of each voltage divider capacitor when it is short-circuited. When a voltage divider capacitor is short-circuited, the current rated power is updated.

[0051] For example, if the current rated power (maximum output power of the transformer secondary side) is 20W when all the voltage divider capacitors are not short-circuited initially, the low-voltage output controller (LVC) detects the current and voltage of the secondary side and obtains the current secondary side power (actual power used by the load connected to the secondary side) as 19W. The set power margin threshold M1 is 5% of the current rated power (the power fluctuation range of secondary equipment such as distribution automation terminals and communication modules on the complete pole-mounted circuit breaker is usually no more than ±5%), that is, M1=1W. The difference between the current secondary side power and the current rated power is 20W-19W=1W, which is equal to the set power margin threshold M1. Then the low-voltage output controller outputs a control signal to short-circuit one of the voltage divider capacitors of the short-circuitable capacitor divider unit, or to continue the state where all the voltage divider capacitors are not short-circuited. As is easily understood, the maximum output power of a transformer refers to the maximum power output of the secondary side of the transformer under the current number of series-connected voltage divider capacitors. It is specifically determined by the total capacitive reactance from the high-voltage end to the primary side of the transformer and is the upper limit of the power output of the circuit hardware topology. The actual power used by the load refers to the real-time power consumption value of the secondary equipment (such as distribution automation terminals, communication modules, protection devices, etc.) of the primary and secondary integrated pole-mounted circuit breakers connected to the secondary side of the transformer, which is the dynamic power demand on the load side.

[0052] When only one short-circuitable capacitor divider unit's voltage divider capacitor is short-circuited, the set rated power is 21W, meaning the current rated power is adjusted to 21W. The low-voltage output regulator continues to monitor the secondary side's current and voltage. It finds that the current secondary side power continues to rise to 20.5W due to the increase in load RL, with a difference of 0.5W from the current rated power. Since this is still less than the power margin threshold M1, the low-voltage output regulator continues to short-circuit one short-circuitable capacitor divider unit's voltage divider capacitor.

[0053] When the voltage divider capacitors of two short-circuitable capacitor divider units are short-circuited, the set rated power is 22W, that is, the current rated power is adjusted to 22W, and the power margin threshold is 5% of the current rated power, specifically 1.1W. The low-voltage output regulator continues to detect the current and voltage on the secondary side. It finds that the current secondary side power has dropped to 20W, and the difference between it and the current rated power is 2W, which is greater than the power margin threshold of 1.1W. Therefore, the low-voltage output regulator will no longer short-circuit the new voltage divider capacitor.

[0054] The power margin callback threshold M2 can be set to 6% of the current rated power (to avoid excessive adjustment, those skilled in the art can also use other power margin settings according to actual application needs), M2=22*6%=1.32W. When the secondary power decreases to a value greater than the power margin callback threshold M2 compared to the current rated power, a previously short-circuited voltage divider capacitor is restored to the circuit, i.e., a previously closed capacitor short-circuit switch K1 is disconnected, allowing the voltage divider capacitor of the short-circuit capacitor voltage divider unit to be reconnected in the capacitor string. Setting a callback allows the transformer to adjust its rated power accordingly when the power decreases, ensuring that the transformer always operates close to its optimal operating range. This allows for the selection of transformers with smaller rated power and more compact size while meeting system power requirements, improving conversion efficiency and reducing module heat generation.

[0055] The low-voltage output regulator (LVC) outputs a control signal to close the capacitor short-circuit switch K1 of the short-circuitable capacitor divider unit CH2. Preferably, the short-circuitable capacitor divider unit closest to the transformer is selected first, as it has the lowest voltage value and the smallest voltage jump during adjustment. The specifications of the voltage divider capacitors in the capacitor divider unit are selected based on whether some or all of the voltage divider capacitors are short-circuited. This ensures that even if some or all of the voltage divider capacitors are short-circuited, the voltage shared by the remaining voltage divider capacitors remains within the acceptable range. In one specific embodiment, when the high-voltage side voltage is 35KV and the total number of capacitor divider units is 30, the rated withstand voltage of a single voltage divider capacitor is 2KV, with a withstand voltage redundancy factor of 1.8. Its maximum withstand voltage is 3.6KV. Even if 10 short-circuitable capacitor divider units are short-circuited, the voltage shared by the remaining 20 voltage divider capacitors is 35KV / 20 = 1.75KV, which is less than 3.6KV, ensuring that the voltage divider capacitors will not break down.

[0056] By detecting the secondary power through the low-voltage output regulator (LVC) and adjusting the output control signal to regulate the short-circuit capacitor voltage divider unit, the rated power threshold of the secondary side can be dynamically adjusted. The power ratio between the primary and secondary sides of the transformer is maintained at a relatively stable value, the magnetic field fluctuation of the transformer core is reduced, and the service life of the transformer is improved.

[0057] Figure 1 In the specific embodiment shown, an inductor L is connected in series between the high-voltage end and the capacitor voltage divider unit. The function of the inductor L is to suppress high-frequency voltage. The normal mains frequency is 50Hz. When high-frequency signals such as lightning occur at the high-voltage end, the capacitive reactance of the capacitor is close to zero at high frequency, and the inductive reactance of the inductor L increases, thereby limiting the current at high frequency and high voltage.

[0058] The capacitor-driven power supply circuit of the integrated primary and secondary pole-mounted circuit breaker described in this invention, by setting up a protection circuit, can short-circuit the primary side of the transformer in the event of overvoltage and lightning strikes, thus preventing the load connected to the transformer and secondary side from burning out. By adding a short-circuitable capacitor voltage divider unit, the rated power of the secondary side can be flexibly adjusted to adapt to different loads.

[0059] In the accompanying drawings of this invention, the correspondence between the corresponding symbols and the Chinese names of the electronic components is as follows: HV - high voltage terminal, CH1 - conventional capacitor voltage divider unit, CH2 - short-circuitable capacitor voltage divider unit, TVS - transient suppression diode, CP - rail-to-rail comparator, C1 - voltage divider capacitor, C2 - voltage regulator capacitor, C3 - primary side capacitor, DL - relay coil, MD - full-bridge rectifier circuit, MK - switching transistor, R1 - first resistor, R2 - second resistor, R3 - third resistor, RL - load, HV - high voltage terminal, HVP - high voltage bootstrap protection module, MK - switching transistor, LVC - low voltage output regulator, L - inductor.

[0060] The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction between the preferred embodiments or a premise based on a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are only for clearly illustrating the inventor's invention verification process and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention shall still be determined by its claims. Similarly, any equivalent structural changes made based on the content of the specification of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A capacitor power supply circuit for a primary and secondary integrated pole-mounted circuit breaker, comprising multiple capacitor voltage divider units connected in series between the high-voltage end HV and the primary side of the transformer T, each capacitor voltage divider unit comprising a voltage divider capacitor C1, and the voltage divider capacitors C1 of all capacitor voltage divider units connected in series between the high-voltage end HV and the primary side of the transformer T. Its features are, A protection circuit is also connected to the primary side of the transformer. The protection circuit includes a bootstrap protection branch connected in parallel with the primary side. The bootstrap protection branch includes a second resistor R2 connected in series and a bootstrap protection switch K2. The other end of the primary side of the transformer that is not connected to the capacitor voltage divider unit is grounded through the primary side capacitor C3. The primary side capacitor C3 is connected in parallel with a high-voltage bootstrap protection module HVP. The output terminal of the high-voltage bootstrap protection module HVP is connected to the control terminal of the bootstrap protection switch K2. The high-voltage bootstrap protection module is configured to control the bootstrap protection switch K2 to close when the voltage of the primary side capacitor C3 increases to a set voltage threshold. Among the plurality of capacitor voltage divider units, at least one short-circuitable capacitor voltage divider unit CH2 is included, and the secondary side of the transformer is connected to a low-voltage output regulator LVC; The low-voltage output regulator (LVC) is configured to: detect the secondary-side power; when the difference between the secondary-side power and the current rated power is less than a set power margin threshold M1, start a delay timer; the system is configured such that the delay time has a settable range; after the delay ends, if the difference between the secondary-side power and the current rated power is still less than the set power margin threshold M1, the LVC performs an adjustment action, outputting a control signal to short-circuit the voltage divider capacitor C1 of at least one of the short-circuitable capacitor divider units CH2, so as to follow the adjustment of the current rated power until the difference between the secondary-side power and the current rated power is greater than the set power margin threshold.

2. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 1, characterized in that, A third resistor R3 is connected between one end of the transformer T connected to the capacitor voltage divider unit and ground, and the third resistor R3 is a varistor.

3. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 1, characterized in that, The bootstrap protection switch K2 is a relay, and the high-voltage bootstrap protection module HVP includes: A full-bridge rectifier circuit MD is connected in parallel with the primary capacitor C3. The input terminals of the full-bridge rectifier circuit MD are respectively connected to the two ends of the primary capacitor C3. The high-voltage bootstrap protection module also includes a switching transistor MK. The switching transistor MK and the relay coil DL are connected in series and then in parallel with the voltage stabilizing capacitor C2. The control terminal of the switching transistor MK is connected to the output terminal of the primary capacitor voltage detection circuit.

4. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 3, characterized in that, A transient breakdown diode (TVS) is connected in parallel across the primary capacitor C3.

5. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 1, characterized in that, The low-voltage output regulator (LVC) is configured to restore the voltage divider capacitor to the circuit when the difference between the secondary power and the current rated power is greater than a set power margin callback threshold, and at least one short-circuitable capacitor divider unit CH2 is short-circuited, until the difference between the secondary power and the current rated power is less than the set power margin callback threshold.

6. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 1, characterized in that, The short-circuitable capacitor voltage divider unit CH2 includes a voltage divider capacitor C1 and a capacitor short-circuit switch K1 connected in parallel with the voltage divider capacitor C1.

7. The capacitor-driven power supply circuit for a primary and secondary integrated pole-mounted circuit breaker as described in claim 6, characterized in that, The capacitor short-circuit switch K1 is a high-voltage optocoupler, and the control terminal of the capacitor short-circuit switch K1 is connected to the low-voltage output regulator LVC.

8. A method for adjusting the capacitor power supply circuit of a primary and secondary integrated pole-mounted circuit breaker, characterized in that, The capacitor-driven power supply circuit for the integrated primary and secondary pole-mounted circuit breaker as described in claim 1 includes the following steps: Step 1. Set the power margin threshold M1 and the rated power of different voltage divider capacitors when they are short-circuited; Step 2. Detect the secondary power. When the difference between the secondary power and the current rated power is less than the set power margin threshold M1, output a control signal to short-circuit the voltage divider capacitor C1 of at least one of the short-circuitable capacitor divider units CH2, so as to adjust the current rated power until the difference between the secondary power and the current rated power is greater than the set power margin threshold.

9. The method for adjusting the capacitor power supply circuit of a primary and secondary integrated pole-mounted circuit breaker as described in claim 8, characterized in that, Step 2 further includes: when the difference between the secondary power and the current rated power is greater than the set power margin callback threshold, and at least one short-circuitable capacitor divider unit CH2 is short-circuited, the voltage divider capacitor C1 is restored to the circuit until the difference between the secondary power and the current rated power is less than the set power margin callback threshold.

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