Energy storage and voltage boost integrated machine measurement and control protection system

Abstract

The application provides a kind of energy storage boost integrated machine measurement and control protection system, belongs to photovoltaic energy storage boost integrated machine technical field, the system includes sensor array, control device and execution unit;The input end of the sensor array is connected with boost transformer, for collecting the state signal of the boost transformer;The input of the control device is connected with the output of the sensor array, for receiving and processing the state signal;The output of the control device is connected with the control end of the execution unit, for outputting protection control signal;The execution unit includes high-voltage circuit breaker and low-voltage circuit breaker, the high-voltage circuit breaker is connected with the high-voltage side of the boost transformer, and the low-voltage circuit breaker is connected with the low-voltage side of the boost transformer. The boost transformer body is quickly protected.

Description

Technical Field

[0001] This invention belongs to the technical field of photovoltaic energy storage booster integrated machine, and particularly relates to a measurement and protection system for an energy storage booster integrated machine. Background Technology

[0002] In recent years, new energy power generation systems, represented by photovoltaics and energy storage, have been widely used. As a key hub connecting the energy storage system and the high-voltage power grid, the reliability and safety of the integrated energy storage step-up transformer directly affect the stability and efficiency of the entire power station. As the core power conversion device within the integrated transformer, the health of the transformer requires special attention and protection.

[0003] In existing integrated energy storage and boost converter technologies, the system's protection functions mainly focus on the bidirectional inverter, battery management system, and cabin fire monitoring. This is a protection approach targeting the main power electronic equipment and the macroscopic environment, aiming to prevent risks such as PCS overload, battery overcharging and over-discharging, and open flames inside the cabin.

[0004] However, the aforementioned protection schemes lack specific and refined protection for the step-up transformer itself. Transformers operate under high voltage and high current conditions for extended periods, and their internal components are susceptible to faults such as winding short circuits, core overheating, and insulation aging. When an internal fault occurs, the system cannot detect and locate it promptly and accurately, relying solely on the actions of the upstream power grid protection devices. This external, non-dedicated protection method results in slow fault clearing and is highly prone to cascading trips due to improper protection setting coordination, expanding the fault range to the entire power station and causing unnecessary power outages and safety risks. Summary of the Invention

[0005] This invention provides a monitoring and protection system for an integrated energy storage and booster transformer, which at least solves the problem of the lack of dedicated and rapid protection for the transformer body in the prior art.

[0006] In a first aspect, embodiments of this application provide a monitoring and protection system for an integrated energy storage and booster unit, the system comprising a sensor array, a control device, and an execution unit; The input terminal of the sensor array is connected to the step-up transformer to collect the status signal of the step-up transformer; The input terminal of the control device is connected to the output terminal of the sensor array, and is used to receive and process the status signal; The output terminal of the control device is connected to the control terminal of the execution unit and is used to output protection control signals; The execution unit includes a high-voltage circuit breaker and a low-voltage circuit breaker. The high-voltage circuit breaker is connected to the high-voltage side of the step-up transformer, and the low-voltage circuit breaker is connected to the low-voltage side of the step-up transformer.

[0007] Furthermore, the sensor array includes a current transformer unit, which includes a high-voltage side current transformer and a low-voltage side current transformer. The high-voltage side current transformer is connected to the high-voltage side of the step-up transformer, and the low-voltage side current transformer is connected to the low-voltage side of the step-up transformer. The sensor array also includes a voltage transformer; the voltage transformer is connected to the high-voltage side of the step-up transformer and is used to collect the voltage signal on the high-voltage side; the output terminal of the voltage transformer is connected to the input terminal of the control device. The sensor array also includes a temperature sensor, a smoke sensor, and a limit switch. The temperature sensor has four monitoring points, which are respectively located at the ends of the A, B, and C phase windings and the upper yoke of the core of the step-up transformer. The smoke sensor is installed inside the compartment of the energy storage booster unit and is used to collect the smoke concentration signal inside the compartment. The limit switch is installed on the door of the integrated energy storage and booster unit and is used to collect the opening and closing status signal of the door.

[0008] Furthermore, the control device includes a microprocessor module, which performs differential protection based on the signals acquired by the sensor array; The microprocessor module also performs over-temperature protection, smoke detection protection, and door opening protection based on the signals collected by the temperature sensor, smoke sensor, and limit switch.

[0009] Furthermore, the control device also includes an AC input module, a DC input module, a digital input module, and a digital output module, which are respectively connected to the microprocessor module; The AC input module is electrically connected to the secondary side of the high-voltage side current transformer and the low-voltage side current transformer respectively through a current acquisition circuit; and is electrically connected to the secondary side of the voltage transformer through a voltage acquisition circuit. The DC input module is electrically connected to the temperature sensor; The digital input module is electrically connected to the smoke sensor and the limit switch, respectively. The switch output module is electrically connected to the high-voltage circuit breaker and the low-voltage circuit breaker respectively; The AC input module, DC input module, digital input module, and digital output module are all electrically connected to the microprocessor module.

[0010] Furthermore, the voltage acquisition circuit includes voltage divider resistors R1 and R2, analog switch U1, and a first-level shift amplifier circuit; The voltage divider resistors R1 and R2 are connected to the secondary side of the voltage transformer PT; The node between the voltage divider resistors R1 and R2 is connected to the input pin X0 of the analog switch U1, and the output pin X of the analog switch U1 is connected to the positive input terminal of the first level shifting amplifier circuit. The output of the first level shifting amplifier circuit outputs the final voltage sampling signal to the intelligent measurement and control unit.

[0011] Furthermore, the first level-shifting amplifier circuit includes: amplifier A1, amplifier A2, resistor R3, resistor R4, resistor R5, diode D1, diode D2, diode Z1, and inverter V1; The negative input terminal of amplifier A1 is connected to the first terminals of resistor R4 and R5. The second terminal of resistor R5 is connected to the output terminal of amplifier A1. The second terminal of resistor R4 is connected to the output terminal of amplifier A2. The positive input terminal of amplifier A2 is connected to the first terminal of resistor R3, the negative terminal of diode D1, and the negative terminal of diode Z1. The second terminal of resistor R3 is connected to power supply VCC. The positive terminal of diode D1 is connected to the first terminal of inverter V1. The second terminal of inverter V1 is connected to the negative terminal of diode D2. The positive terminal of diode Z1 is connected to the third terminal of inverter V1 and the positive terminal of diode D2.

[0012] Furthermore, the current acquisition circuit includes an I / V conversion circuit, an analog switch U2, and a second-level shift amplifier circuit; The I / V conversion circuit receives the secondary current signal from the current transformer CT and converts the secondary current signal into a corresponding voltage signal. The voltage signal is input to the input pin Y0 of the analog switch U2, and the output pin Y of the analog switch U2 is connected to the positive input terminal of the second level shift amplifier circuit. The second level shifting amplifier circuit DC biases and amplifies the input voltage signal, and outputs it to the intelligent measurement and control unit for calculating electrical quantity protection criteria.

[0013] Furthermore, the second level-shifting amplifier circuit includes: amplifier A3, amplifier A4, resistor R6, resistor R7, resistor R8, diode D3, diode D4, diode Z2, and inverter V2; The negative input terminal of amplifier A3 is connected to the first terminals of resistor R7 and resistor R8. The second terminal of resistor R8 is connected to the output terminal of amplifier A3. The second terminal of resistor R7 is connected to the output terminal of amplifier A4. The positive input terminal of amplifier A4 is connected to the first terminal of resistor R6, the negative terminal of diode D3, and the negative terminal of diode Z2. The second terminal of resistor R6 is connected to power supply VCC. The positive terminal of diode D3 is connected to the first terminal of inverter V2. The second terminal of inverter V2 is connected to the negative terminal of diode D4. The positive terminal of diode Z2 is connected to the third terminal of inverter V2 and the positive terminal of diode D4.

[0014] Furthermore, the switch output module includes a resistor R9, a transistor N1, an optocoupler OI, a current-limiting resistor R10, a protection diode L1, a driver transistor N2, a resistor R11, a diode D5, and a relay JDQ. One end of the resistor R9 is connected to the control signal output terminal Q1 of the microprocessor module, and the other end of the resistor R9 is connected to the base of the transistor N1, which is used to receive the control signal and drive the transistor N1 to conduct. The emitter of the transistor N1 is grounded, and the collector of the transistor N1 is connected to the negative input terminal of the optocoupler OI through the current-limiting resistor R10. The positive input terminal of the optocoupler OI is connected to the power supply VCC, which is used to electrically isolate the microprocessor module from the high-voltage drive circuit. The output collector of the optocoupler OI is connected to the power supply, and the output emitter of the optocoupler OI is connected to the base of the driving transistor N2 through resistor R11 and protection diode L1. The emitter of the driving transistor N2 is grounded. The collector of the driving transistor N2 is connected to the coil of the relay JDQ and the positive terminal of the diode D5, and is used to output a control signal to drive the relay JDQ to operate. The normally open contact of the relay JDQ is connected in series in the control circuits of the high-voltage circuit breaker and the low-voltage circuit breaker of the energy storage booster unit to realize the protection tripping of the equipment.

[0015] Furthermore, the control device also includes a communication module, which is connected to the microprocessor module and is used to upload the collected data and protection action information to the background monitoring system; The control device also includes a human-machine interface module, which is connected to the microprocessor module and is used to display the measurement status, the circuit breaker position status, and set protection parameters.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: The energy storage step-up integrated unit monitoring and protection system provided in this application achieves dedicated monitoring and protection of the step-up transformer within the energy storage step-up integrated unit through a monitoring and protection system composed of a sensor array, a control device, and an execution unit. The sensor array directly collects electrical and non-electrical signals of the transformer, the control device performs real-time processing and judgment, and the execution unit is responsible for rapid action. This addresses the deficiency in existing technical solutions that lack dedicated protection for the step-up transformer itself, transforming transformer protection from passive to active, thereby improving and strengthening the protection system of the energy storage system and eliminating protection blind spots.

[0017] This application integrates the execution units of high-voltage and low-voltage circuit breakers and collaborates with the control device to construct a fast-response fault isolation mechanism. When the control device determines that a transformer fault has occurred based on sensor signals, it directly drives the corresponding circuit breaker to trip. This solves the problem of slow fault clearing and easy over-level tripping caused by the reliance on upstream protection in existing solutions. Through the system's own fast protection logic and execution mechanism, the fault can be accurately and quickly limited to the step-up transformer body for clearing, shortening the fault clearing time, eliminating protection over-level tripping, and ensuring the continuous operation of non-faulty parts. Attached Figure Description

[0018] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the measurement, control and protection system of the integrated energy storage and booster unit described in this invention.

[0020] Figure 2 This is a schematic diagram of the voltage acquisition circuit of the energy storage booster integrated machine measurement and control protection system described in this invention.

[0021] Figure 3 This is a schematic diagram of the current acquisition circuit of the energy storage booster integrated machine measurement and control protection system described in this invention.

[0022] Figure 4 This is a circuit diagram of the switch output module of the energy storage booster integrated machine measurement and control protection system described in this invention.

[0023] Figure 5 This is a circuit diagram of the opto-isolation circuit of the energy storage booster integrated machine measurement and protection system described in this invention.

[0024] Figure 6 This is a schematic diagram of the differential protection action characteristics of the integrated energy storage and booster unit measurement and control protection system described in this invention.

[0025] Figure 7 This is a sinusoidal waveform diagram with harmonics for the energy storage booster integrated machine measurement and protection system described in this invention. Detailed Implementation

[0026] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, 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] This application provides a measurement and protection system for an integrated energy storage and step-up transformer, which solves the current urgent technical problem of needing a dedicated and rapid protection system for the step-up transformer itself.

[0028] The technical solutions proposed in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic block diagram of a monitoring and protection system for an integrated energy storage booster unit, provided as an embodiment of this application. Figure 1 As shown in the figure, an energy storage booster integrated machine monitoring and protection system is provided in this application embodiment, characterized in that the system includes a sensor array, a control device, and an execution unit; The input terminal of the sensor array is connected to the step-up transformer to collect the status signal of the step-up transformer; The input terminal of the control device is connected to the output terminal of the sensor array, and is used to receive and process the status signal; The output terminal of the control device is connected to the control terminal of the execution unit and is used to output protection control signals; The execution unit includes a high-voltage circuit breaker and a low-voltage circuit breaker. The high-voltage circuit breaker is connected to the high-voltage side of the step-up transformer, and the low-voltage circuit breaker is connected to the low-voltage side of the step-up transformer.

[0030] It should be noted that the sensor array includes current transformer units, which consist of a high-voltage side current transformer and a low-voltage side current transformer. The high-voltage side current transformer is connected to the high-voltage side of the step-up transformer, and the low-voltage side current transformer is connected to the low-voltage side of the step-up transformer. The high-voltage side current transformer is fixed to the incoming busbar of the high-voltage compartment or is an integrated current transformer of a high-voltage circuit breaker, while the low-voltage side current transformer is fixed through-type to the low-voltage busbar of the step-up transformer. Both the high-voltage and low-voltage side current transformers have measuring windings and protection windings, enabling them to collect current during normal operation and current during short-circuit faults.

[0031] The sensor array also includes a voltage transformer; the voltage transformer is connected to the high-voltage side of the step-up transformer and is used to collect the voltage signal on the high-voltage side; the output terminal of the voltage transformer is connected to the input terminal of the control device. The sensor array also includes a temperature sensor, a smoke sensor, and a limit switch. The temperature sensor has four monitoring points, which are respectively set at the ends of the A, B, and C phase windings and the upper yoke of the core of the step-up transformer. It is bonded with high-temperature resistant silicone and bound with stainless steel cable ties, and is tightly attached to the core heating area. The wiring uses a three-core shielded wire, and the shielding layer is grounded to resist interference. It can monitor the temperature of the coils and core of the step-up transformer during operation and transmit PT100 analog signals.

[0032] The smoke sensor is installed inside the cabin of the energy storage and booster unit, specifically in the high-voltage chamber, transformer chamber, communication and power chamber, and near the louvers on the top of the cabin, to collect smoke concentration signals inside the cabin. The limit switch is installed on the hatch of the integrated energy storage and booster unit, specifically on the upper part of the hatch of the high-voltage compartment, transformer compartment, and communication power compartment of the integrated energy storage and booster unit, and is used to collect the opening and closing status signals of the hatch.

[0033] In one exemplary embodiment, the control device includes a microprocessor module that performs differential protection based on signals acquired by the sensor array; When the microprocessor module performs differential protection, it calculates the differential current and braking current on the high-voltage side and the low-voltage side, and outputs protection control signals according to the ratio differential action equation or differential current instantaneous trip condition.

[0034] Differential protection is the primary protection against internal transformer faults and is widely used in 35kV and above substations. It is mainly used to protect against various phase-to-phase short-circuit faults occurring within the windings and leads of double-winding or triple-winding transformers, and can also protect against single-phase turn-to-turn short-circuit faults. The scope of differential protection includes the electrical equipment between the current transformers constituting the transformer differential protection and the wires connecting these devices. Simply put, it includes the equipment between the two input current transformers (CTs). Because differential protection does not operate on faults outside the protection zone, it does not need to coordinate with the protection of adjacent components outside the protection zone in terms of operating values ​​and operating time. When a fault occurs within the protection zone, the setting head can operate instantaneously. Differential protection has a simple principle, uses simple electrical quantities, has a clearly defined protection range, and requires no time delay, so it is used for the main protection of transformers. Differential protection is essential to ensure the safe operation of energy storage step-up transformers.

[0035] Ratio differential protection can reflect phase-to-phase short circuit faults inside the transformer, single-phase ground faults on the high-voltage side, and inter-turn and inter-layer short circuit faults. It must consider both inrush current and over-excitation operating conditions, as well as abnormal conditions of the transformer.

[0036] Due to differences in transformer connection groups and current transformer (CT) ratios on each side, the amplitude and phase of the current on each side of the transformer also differ. Differential protection must first eliminate these effects. The intelligent measurement and control unit uses digital methods to compensate for the CT ratio and phase, thereby eliminating the differences in current amplitude and phase on each side of the transformer.

[0037] The device adopts the conventional ratio differential principle, and its operating equation is:

[0038]

[0039] In the formula , These are the phase currents on the high-voltage side and the low-voltage side, respectively. For differential current, This is the minimum operating current setting value for the differential. For braking current, This is the minimum braking current setting value. This is the setting value for the ratio braking coefficient. The balance factor is calculated based on the transformer capacity, the measured rated voltage of the high and low voltage transformers, and the transformer turns ratio, as follows:

[0040] In the formula The rated capacity of the transformer. This is the rated voltage on the high-voltage side of the transformer. This is the rated voltage on the low-voltage side of the transformer. For the current transformer ratio on the high-voltage side, The current transformer ratio is used on the low-voltage side. The reference direction of the current on each side is taken as the direction pointing towards the transformer. The device uses the second harmonic content in the differential current to identify the inrush current. The judgment equation is as follows:

[0041] In the formula: The second harmonic in differential current, For the fundamental wave in differential current, The second harmonic coefficient is 0.15. If the phase differential current satisfies the above formula, then the blocking ratio differential protection has the following operating characteristics: Figure 6 As shown.

[0042] The microprocessor module uses an STM32 microcontroller. Based on signals collected by the temperature sensor, smoke sensor, and limit switch, the microprocessor module also performs over-temperature protection, smoke detection protection, and door opening protection.

[0043] The microprocessor module executes multi-level collaborative protection logic, including: In response to a fault signal in the main body of the step-up transformer, the high-voltage circuit breaker and the low-voltage circuit breaker are controlled to trip instantaneously; In response to a fault signal on the low-voltage side of the step-up transformer, the low-voltage circuit breaker is controlled to trip after a delay. In response to a fault signal on the high-voltage side of the step-up transformer, the high-voltage circuit breaker is controlled to trip after a delay.

[0044] According to another embodiment of the present invention, the control device further includes an AC input module, a DC input module, a digital input module, and a digital output module, which are respectively connected to the microprocessor module; The AC input module is electrically connected to the secondary side of the high-voltage side current transformer and the low-voltage side current transformer respectively through a current acquisition circuit; and is electrically connected to the secondary side of the voltage transformer through a voltage acquisition circuit. The DC input module is electrically connected to the temperature sensor; it is used to receive the PT100 analog signal collected by the transformer temperature sensor. The digital input module is electrically connected to the smoke sensor and the limit switch, respectively. The switch output module is electrically connected to the high-voltage circuit breaker and the low-voltage circuit breaker respectively; The AC input module, DC input module, digital input module, and digital output module are all electrically connected to the microprocessor module.

[0045] According to embodiments of this application, in conjunction with Figures 2 to 3The 0-5A small current and 0-100V input voltage after passing through the current transformer unit are adjusted to a signal range suitable for A / D conversion. The current acquisition circuit and voltage acquisition circuit simultaneously sample the voltage and current of a specific circuit.

[0046] like Figure 2 As shown, the voltage acquisition circuit includes voltage divider resistors R1 and R2, analog switch U1, and a first-level shift amplifier circuit. The primary side of the voltage transformer PT is connected in parallel to the high-voltage side output terminal of the energy storage booster unit for electrical isolation and voltage reduction of the high-voltage side. The voltage divider resistors R1 and R2 are connected to the secondary side of the voltage transformer PT and are used to perform voltage division and conditioning on the stepped-down voltage. The node between the voltage divider resistors R1 and R2 is connected to the input pin X0 of the analog switch U1, and the output pin X of the analog switch U1 is connected to the positive input terminal of the first level shift amplifier circuit, which is used to convert the acquired AC voltage signal into a positive signal and transmit it to the intelligent measurement and control unit. The output of the first level shifting amplifier circuit outputs the final voltage sampling signal to the intelligent measurement and control unit, which is used to participate in the calculation of electrical quantity protection criteria.

[0047] In power grids, power harmonics are generated by factors such as poor power generation quality, transmission and distribution systems, and electrical equipment. These harmonics reduce grid capacity, damage electrical equipment, and affect the accuracy of power measurements. Therefore, accurately understanding the operating status of the power system and minimizing these issues requires significant research into power data acquisition and monitoring to reduce harmonic damage.

[0048] Depend on Figure 7 From the sinusoidal waveform with harmonics, we can see that the red curve represents the voltage graph under sinusoidal steady-state conditions, and its value can be expressed as:

[0049] In the formula, The effective value of the voltage has an amplitude of ; Let be the initial phase angle, and ; Angular frequency, For frequency, It is a periodicity.

[0050] The green curve in the sine wave with harmonics represents a sine wave with the 3rd, 5th, and 7th harmonics.

[0051] Fourier series is an effective method for studying and analyzing harmonic distortion. Fourier decomposition allows for the examination of various components of the distorted waveform.

[0052] Generally speaking, any periodic waveform can be expanded into a Fourier series, that is:

[0053] in, It is the zero-sequence DC component, where the coefficient value is:

[0054]

[0055]

[0056] The intelligent measurement and control unit collects power parameters and then performs power calculations. During the calculation process, the continuous signal is first... Converted into pulse sequence In other words, it is converted into a discrete signal. Therefore, a common problem exists in the signal conversion process: how to ensure that the signal is not lost during sampling and can truly reflect the continuous signal. The variation pattern is shown in Shannon's theorem, which provides the theoretical basis for selecting the sampling period. If the intelligent measurement and control unit requires a minimum sampling frequency to ensure signal accuracy during the sampling process, then a minimum sampling frequency is necessary.

[0057] For a continuous signal with a finite spectrum, perform continuous signal processing. During sampling, when the sampling frequency can meet the requirements... At that time, the sampling signal It can fully reflect continuous signals. The changing pattern. Therefore, we obtain the formula:

[0058]

[0059] in, Continuous signal The highest angular frequency; This is the sampling angular frequency.

[0060] In integrated energy storage and voltage booster units, due to the extensive use of components such as current transmitters and voltage transmitters, harmonics are inevitably present in the power distribution system circuits. To eliminate the influence of harmonic components on the circuit, a 50Hz fundamental frequency component is selected, and the acquisition algorithm adopts the full-cycle Fourier algorithm. Assume:

[0061] —The DC component of each electrical quantity; ——No. The amplitude of the second harmonic component.

[0062] The method for obtaining the fundamental component is as follows: Multiply and The integration over one cycle can eliminate the DC and harmonic components of the signal, thus obtaining the fundamental component of the signal.

[0063] Equation (1) Equation (2) The summation of the N sampled values ​​for the entire period can be substituted into equations (1) and (2) to obtain the result.

[0064]

[0065]

[0066] In the formula: —The real part of each electrical quantity value; —The imaginary part of each electrical quantity value.

[0067] The values ​​of voltage, current, active power, and reactive power in the system can be calculated:

[0068]

[0069]

[0070]

[0071] In the formula: , —These are the real parts of the voltage and the real parts of the current in the fundamental frequency region, respectively. , —These are the imaginary parts of the voltage and current of the fundamental frequency component, respectively. When the system frequency is not 50Hz, the sampling frequency will change or become a non-integer value, resulting in fewer than 36 data points collected per cycle. This will also cause errors when calculating using the formula mentioned above. Therefore, the next step is to adjust the sampling period. , sampling rate The sampling period is changed to 36 times the actual frequency. In the software, only the microcontroller's internal timer register needs to be modified to adjust the system's sampling period. When the sampling period changes, the value of the same input quantity within the sampling interval will also be adjusted accordingly. The system's sampling frequency can be adjusted based on the frequency calculated from the sampled values, thus ensuring that the obtained sampling frequency accurately reflects the actual signal waveform and guarantees the accuracy of the entire system's data.

[0072] In one embodiment, the first level-shifting amplifier circuit includes: amplifier A1, amplifier A2, resistor R3, resistor R4, resistor R5, diode D1, diode D2, diode Z1, and inverter V1. The negative input terminal of amplifier A1 is connected to the first terminals of resistor R4 and resistor R5. The second terminal of resistor R5 is connected to the output terminal of amplifier A1. The second terminal of resistor R4 is connected to the output terminal of amplifier A2. The positive input terminal of amplifier A2 is connected to the first terminal of resistor R3, the negative terminal of diode D1, and the negative terminal of diode Z1. The second terminal of resistor R3 is connected to power supply VCC. The positive terminal of diode D1 is connected to the first terminal of inverter V1. The second terminal of inverter V1 is connected to the negative terminal of diode D2. The positive terminal of diode Z1 is connected to the third terminal of inverter V1 and the positive terminal of diode D2.

[0073] As an example, such as Figure 3 As shown, the current acquisition circuit includes an I / V conversion circuit (which converts the input current and voltage into a recognizable range), an analog switch U2, and a second-level shift amplifier circuit. The I / V conversion circuit receives the secondary current signal from the current transformer CT and converts the secondary current signal into a corresponding voltage signal. The voltage signal is input to the input pin Y0 of the analog switch U2, and the output pin Y of the analog switch U2 is connected to the positive input terminal of the second level shift amplifier circuit, which is used to switch and transmit the voltage signal corresponding to each phase current in a time-division manner. The second level shifting amplifier circuit DC biases and amplifies the input voltage signal to match the sampling range of the intelligent measurement and control unit, and outputs it to the intelligent measurement and control unit for use in the calculation of electrical quantity protection criteria.

[0074] The second level shifting amplifier circuit includes: amplifier A3, amplifier A4, resistor R6, resistor R7, resistor R8, diode D3, diode D4, diode Z2, and inverter V2; The negative input terminal of amplifier A3 is connected to the first terminals of resistor R7 and resistor R8. The second terminal of resistor R8 is connected to the output terminal of amplifier A3. The second terminal of resistor R7 is connected to the output terminal of amplifier A4. The positive input terminal of amplifier A4 is connected to the first terminal of resistor R6, the negative terminal of diode D3, and the negative terminal of diode Z2. The second terminal of resistor R6 is connected to power supply VCC. The positive terminal of diode D3 is connected to the first terminal of inverter V2. The second terminal of inverter V2 is connected to the negative terminal of diode D4. The positive terminal of diode Z2 is connected to the third terminal of inverter V2 and the positive terminal of diode D4.

[0075] It needs to be further explained that, in combination Figure 4 The switch output module includes a resistor R9, a transistor N1, an optocoupler OI, a current-limiting resistor R10, a protection diode L1, a driver transistor N2, a resistor R11, a diode D5, and a relay JDQ. One end of the resistor R9 is connected to the control signal output terminal Q1 of the microprocessor module, and the other end of the resistor R9 is connected to the base of the transistor N1, which is used to receive the control signal and drive the transistor N1 to conduct. The emitter of the transistor N1 is grounded, and the collector of the transistor N1 is connected to the negative input terminal of the optocoupler OI through the current-limiting resistor R10. The positive input terminal of the optocoupler OI is connected to the power supply VCC, which is used to electrically isolate the microprocessor module from the high-voltage drive circuit. The output collector of the optocoupler OI is connected to the power supply, and the output emitter of the optocoupler OI is connected to the base of the driving transistor N2 through a resistor R11 and a protection diode L1. The emitter of the driving transistor N2 is grounded. The protection diode L1 is connected in series between the output emitter of the optocoupler OI and the base of the driving transistor N2 to prevent reverse voltage from breaking down the optocoupler and driving the driving transistor N2 to saturate and conduct. The collector of the driving transistor N2 is connected to the coil of the relay JDQ and the positive terminal of the diode D5, and is used to output a control signal to drive the relay JDQ to operate. The normally open contact of the relay JDQ is connected in series in the control circuits of the high-voltage circuit breaker and the low-voltage circuit breaker of the energy storage booster unit to realize the protection tripping of the equipment.

[0076] The switch output module is used to transmit control signals to high-voltage circuit breakers and low-voltage circuit breakers, and to provide switch control signals to external circuits. It can realize remote control operation, and can also automatically control the high-voltage circuit breaker and low-voltage circuit breaker to trip and disconnect the circuit after a fault is detected. The operating principle of the digital output module is as follows: Figure 4As shown, the microcontroller transmits the acquired data to the buffer latch. At this point, two scenarios exist: In the first scenario, when the latch's output state Q1 is 0, transistor N1 is cut off, opto-isolator OI is input, diode L1 is not conducting, transistor N2 is cut off, and no current flows through the coil of relay JDQ. Therefore, the normally open contact B of relay JDQ is open, and the normally closed contact of relay JDQ is closed. In the second scenario, when the latch's output state Q1 is 1, transistor N1 is conducting, opto-isolator OI is input, diode L1 is conducting, transistor N2 is conducting, and current flows through the coil of relay JDQ. Therefore, the normally open contact of relay JDQ is closed, and the normally closed contact of relay JDQ is open.

[0077] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another energy storage booster integrated machine monitoring and protection system is provided. The control device further includes a communication module, which is connected to the microprocessor module and is used to upload the collected data and protection action information to the background monitoring system. The control device also includes a human-machine interface module, which is connected to the microprocessor module and is used to display the measurement status, the circuit breaker position status, and set protection parameters.

[0078] Combination Figure 5 The control device is equipped with an opto-isolation circuit between itself, the sensor array, and the execution unit. The reliability of the measurement and control protection system is one of the key factors for the reliable operation of the entire intelligent energy storage booster system. However, many interference sources exist during the actual operation of the energy storage booster, such as the operation of high-voltage equipment, the operation of electrical equipment in low-voltage current circuits, and surge voltage caused by lightning. Therefore, anti-interference design is also a key technology. To prevent the reliability of the transformer substation from decreasing due to interference, opto-isolation measures are adopted between the switch input / output circuits, the communication interface circuit, and the microcontroller minimum system, and an optocoupler circuit is added. A hardware self-recovery circuit is used, which resets the microcomputer and initializes it when the program goes off track. To prevent surge voltage interference, TVS diodes and ferrite beads are added to the circuit for filtering, adapting to the strong electromagnetic environment of the power station.

[0079] Complete the circuit design according to the above scheme, and conduct circuit testing to verify whether the circuit board meets the requirements and the rationality of the circuit design.

[0080] (1) Voltage and current accuracy test Under normal operating conditions, a standard voltage source of 57V and 5A is supplied to the measurement and control system using a standard tester. The data measured from the standard source is compared with the standard data, and then the circuit correction coefficient is obtained. The intelligent measurement and control unit corrected using these parameters can improve its measurement accuracy.

[0081] According to standard DL / T721-2000, the measurement accuracy of voltage and current of this measurement and control system is required to be 0.5 class under normal conditions. The system was tested using the specified voltage and current provided by a standard tester. The results are shown in Tables 1 and 2, respectively.

[0082] Table 1 Voltage Measurement Accuracy

[0083] Table 2 Current Measurement Accuracy

[0084] Tables 1 and 2 only list the measurement data for 3 voltage channels and 3 current channels. The test results for the 6 input channels that are not listed also meet the allowable error.

[0085] (2) Anti-interference test High-frequency interference and surge interference tests shall be performed in accordance with the provisions of GB / T15153.1, and fast transient pulse interference tests shall be performed in accordance with the provisions of GB / T17626.4.

[0086] Under normal working atmospheric conditions, when the system is in operation, the fast transient pulse, surge and high frequency interference specified in the standard are applied sequentially to the signal circuit, control circuit and AC power circuit using an interference generator. The system still works normally, stably and reliably. The test results are shown in Table 3.

[0087] Table 3 Anti-interference test

[0088] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0089] For those skilled in the art, designing different forms of control circuits according to the teachings of this invention does not require creative effort. Changes, modifications, substitutions, and variations made to the embodiments without departing from the principles and spirit of this invention still fall within the scope of protection of this invention.

Claims

1. A monitoring and protection system for an integrated energy storage and booster unit, characterized in that, The system includes a sensor array, a control device, and an execution unit; The input terminal of the sensor array is connected to the step-up transformer to collect the status signal of the step-up transformer; The input terminal of the control device is connected to the output terminal of the sensor array, and is used to receive and process the status signal; The output terminal of the control device is connected to the control terminal of the execution unit and is used to output protection control signals; The execution unit includes a high-voltage circuit breaker and a low-voltage circuit breaker. The high-voltage circuit breaker is connected to the high-voltage side of the step-up transformer, and the low-voltage circuit breaker is connected to the low-voltage side of the step-up transformer.

2. The integrated energy storage and booster unit monitoring and protection system according to claim 1, characterized in that, The sensor array includes a current transformer unit, which includes a high-voltage side current transformer and a low-voltage side current transformer. The high-voltage side current transformer is connected to the high-voltage side of the step-up transformer, and the low-voltage side current transformer is connected to the low-voltage side of the step-up transformer. The sensor array also includes a voltage transformer; the voltage transformer is connected to the high-voltage side of the step-up transformer and is used to collect the voltage signal on the high-voltage side; the output terminal of the voltage transformer is connected to the input terminal of the control device. The sensor array also includes a temperature sensor, a smoke sensor, and a limit switch. The temperature sensor has four monitoring points, which are respectively located at the ends of the A, B, and C phase windings and the upper yoke of the core of the step-up transformer. The smoke sensor is installed inside the compartment of the energy storage booster unit and is used to collect the smoke concentration signal inside the compartment. The limit switch is installed on the door of the integrated energy storage and booster unit and is used to collect the opening and closing status signal of the door.

3. The integrated energy storage and booster unit monitoring and protection system according to claim 2, characterized in that, The control device includes a microprocessor module, which performs differential protection based on the signals acquired by the sensor array. The microprocessor module also performs over-temperature protection, smoke detection protection, and door opening protection based on the signals collected by the temperature sensor, smoke sensor, and limit switch.

4. The integrated energy storage and booster unit monitoring and protection system according to claim 3, characterized in that, The control device further includes an AC input module, a DC input module, a digital input module, and a digital output module, which are respectively connected to the microprocessor module. The AC input module is electrically connected to the secondary side of the high-voltage side current transformer and the low-voltage side current transformer respectively through a current acquisition circuit; and is electrically connected to the secondary side of the voltage transformer through a voltage acquisition circuit. The DC input module is electrically connected to the temperature sensor; The digital input module is electrically connected to the smoke sensor and the limit switch, respectively. The switch output module is electrically connected to the high-voltage circuit breaker and the low-voltage circuit breaker respectively; The AC input module, DC input module, digital input module, and digital output module are all electrically connected to the microprocessor module.

5. The integrated energy storage and booster unit monitoring and protection system according to claim 4, characterized in that, The voltage acquisition circuit includes voltage divider resistors R1 and R2, analog switch U1, and a first-level shift amplifier circuit; The voltage divider resistors R1 and R2 are connected to the secondary side of the voltage transformer PT; The node between the voltage divider resistors R1 and R2 is connected to the input pin X0 of the analog switch U1, and the output pin X of the analog switch U1 is connected to the positive input terminal of the first level shifting amplifier circuit. The output of the first level shifting amplifier circuit outputs the final voltage sampling signal to the intelligent measurement and control unit.

6. The integrated energy storage and booster unit monitoring and protection system according to claim 5, characterized in that, The first level-shifting amplifier circuit includes: amplifier A1, amplifier A2, resistor R3, resistor R4, resistor R5, diode D1, diode D2, diode Z1, and inverter V1; The negative input terminal of amplifier A1 is connected to the first terminals of resistor R4 and resistor R5. The second terminal of resistor R5 is connected to the output terminal of amplifier A1. The second terminal of resistor R4 is connected to the output terminal of amplifier A2. The positive input terminal of amplifier A2 is connected to the first terminal of resistor R3, the negative terminal of diode D1, and the negative terminal of diode Z1. The second terminal of resistor R3 is connected to power supply VCC. The positive terminal of diode D1 is connected to the first terminal of inverter V1. The second terminal of inverter V1 is connected to the negative terminal of diode D2. The positive terminal of diode Z1 is connected to the third terminal of inverter V1 and the positive terminal of diode D2.

7. The integrated energy storage and booster unit monitoring and protection system according to claim 6, characterized in that, The current acquisition circuit includes an I / V conversion circuit, an analog switch U2, and a second-level shift amplifier circuit; The I / V conversion circuit receives the secondary current signal from the current transformer CT and converts the secondary current signal into a corresponding voltage signal. The voltage signal is input to the input pin Y0 of the analog switch U2, and the output pin Y of the analog switch U2 is connected to the positive input terminal of the second level shift amplifier circuit. The second level shifting amplifier circuit DC biases and amplifies the input voltage signal, and outputs it to the intelligent measurement and control unit for calculating electrical quantity protection criteria.

8. The integrated energy storage and booster unit monitoring and protection system according to claim 7, characterized in that, The second level shifting amplifier circuit includes: amplifier A3, amplifier A4, resistor R6, resistor R7, resistor R8, diode D3, diode D4, diode Z2, and inverter V2; The negative input terminal of amplifier A3 is connected to the first terminals of resistor R7 and resistor R8. The second terminal of resistor R8 is connected to the output terminal of amplifier A3. The second terminal of resistor R7 is connected to the output terminal of amplifier A4. The positive input terminal of amplifier A4 is connected to the first terminal of resistor R6, the negative terminal of diode D3, and the negative terminal of diode Z2. The second terminal of resistor R6 is connected to power supply VCC. The positive terminal of diode D3 is connected to the first terminal of inverter V2. The second terminal of inverter V2 is connected to the negative terminal of diode D4. The positive terminal of diode Z2 is connected to the third terminal of inverter V2 and the positive terminal of diode D4.

9. The integrated energy storage and booster unit monitoring and protection system according to claim 8, characterized in that, The digital output module includes a resistor R9, a transistor N1, an optocoupler OI, a current-limiting resistor R10, a protection diode L1, a driver transistor N2, a resistor R11, a diode D5, and a relay JDQ. One end of the resistor R9 is connected to the control signal output terminal Q1 of the microprocessor module, and the other end of the resistor R9 is connected to the base of the transistor N1, which is used to receive the control signal and drive the transistor N1 to conduct. The emitter of the transistor N1 is grounded, and the collector of the transistor N1 is connected to the negative input terminal of the optocoupler OI through the current-limiting resistor R10. The positive input terminal of the optocoupler OI is connected to the power supply VCC, which is used to electrically isolate the microprocessor module from the high-voltage drive circuit. The output collector of the optocoupler OI is connected to the power supply, and the output emitter of the optocoupler OI is connected to the base of the driving transistor N2 through resistor R11 and protection diode L1. The emitter of the driving transistor N2 is grounded. The collector of the driving transistor N2 is connected to the coil of the relay JDQ and the positive terminal of the diode D5, and is used to output a control signal to drive the relay JDQ to operate. The normally open contact of the relay JDQ is connected in series in the control circuits of the high-voltage circuit breaker and the low-voltage circuit breaker of the energy storage booster unit to realize the protection tripping of the equipment.

10. The integrated energy storage and booster unit monitoring and protection system according to claim 9, characterized in that, The control device also includes a communication module, which is connected to the microprocessor module and is used to upload the collected data and protection action information to the background monitoring system. The control device also includes a human-machine interface module, which is connected to the microprocessor module and is used to display the measurement status, the circuit breaker position status, and set protection parameters.

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