Power distribution room electric energy comprehensive treatment system

Abstract

The invention relates to the technical field of electric energy treatment, and provides a power distribution room electric energy comprehensive treatment system comprising a detection module used for collecting three-phase voltage and three-phase current signals of a power grid side and load side current signals of a power distribution room, and performing coordinate transformation and filtering processing on the signals to obtain a harmonic current value and a fundamental current value; the detection module comprises a data acquisition unit, a CLARK conversion unit, a PARK conversion unit and a low-pass filtering unit; the data acquisition unit adopts a 16-bit ADC (Analog to Digital Converter) to perform real-time acquisition on a current signal at a sampling frequency of 20kHz; and the control module is used for calculating the switching pulse frequency according to the harmonic current value. Through the cooperative compensation of the STATCOM device and the phase-change switch, the system greatly reduces the harmonic current distortion rate of a power grid, meets the national standard requirements, effectively solves the problems of cable overheating, motor loss increase and the like caused by harmonic waves, remarkably improves the power factor, greatly reduces the active power loss, and achieves an unexpected energy-saving effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric energy management, in particular to a power distribution room electric energy comprehensive management system. BACKGROUND

[0002] In the industrial power distribution field, with the large-scale application of non-linear loads such as frequency converters and thyristor converter devices in alumina plants, metallurgical workshops and other scenarios, low-voltage power distribution systems generally face the problem of deterioration of power quality. The measured data shows that the harmonic current distortion rate in a 400V power distribution system is often 20% to 40%, the three-phase current imbalance degree exceeds 20%, and the power factor is generally lower than 0.85. Such problems not only cause cable overheating and motor loss to increase by more than 30%, but also cause the failure rate of frequency converters to rise, seriously affecting the continuity of industrial production and the service life of equipment.

[0003] In the current power quality management scheme, the traditional passive filter can only compensate for fixed frequency harmonics and cannot adapt to changes in dynamic loads such as frequency converter groups in alumina plants; the SVC static var generator uses step-by-step compensation, with a response time of more than 50ms, making it difficult to track rapidly fluctuating reactive power demand, resulting in low compensation accuracy and easy voltage fluctuation. In addition, although the SVG device based on traditional PI control can dynamically compensate for reactive power, it cannot simultaneously manage three-phase imbalance problems, and when used alone, the harmonic distortion rate can only be reduced to 10% to 15%; the commutating switch and the compensation device operate independently, lack real-time data interaction, resulting in a compensation efficiency of less than 80%, and overcompensation or undercompensation occurs frequently. Moreover, the existing system lacks real-time monitoring of power grid state and adaptive adjustment function, cannot dynamically optimize the compensation strategy according to load changes, causes the line loss rate to be higher than 10% for a long time, and causes the equipment to operate in a poor power quality environment for a long time, reducing the service life by about 40%.

[0004] To solve the above problems, the power distribution room electric energy comprehensive management system provided by the present application achieves breakthrough through multi-module collaborative innovation: the detection module real-time acquires three-phase voltage and current signals and performs coordinate transformation and filtering, the control module introduces the modulation model predictive control (M2PC) algorithm, combines cost function optimization and power prediction formula to realize precise pulse control, and the compensation module synchronously solves the problems of harmonic suppression, three-phase balance regulation and power factor improvement through the collaborative action of the commutating switch array and the STATCOM device. This scheme reduces the harmonic distortion rate, improves the power factor, controls the three-phase imbalance degree within 5%, reduces the line loss rate, and reduces the failure rate of frequency converters. SUMMARY

[0005] To solve the problem that the traditional passive filter can only compensate for fixed frequency harmonics and cannot adapt to changes in dynamic loads such as frequency converter groups in alumina plants, the present application provides a power distribution room electric energy comprehensive management system.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a comprehensive power management system for a power distribution room, comprising:

[0007] The detection module is used to collect three-phase voltage, three-phase current and load-side current signals from the power grid side of the distribution room, and to perform coordinate transformation and filtering on the signals to obtain harmonic current values ​​and fundamental current values. The detection module includes a data acquisition unit, a Clark transformation unit, a Park transformation unit and a low-pass filter unit. The data acquisition unit uses a 16-bit ADC to collect the current signal in real time at a sampling frequency of 20kHz.

[0008] The control module is used to calculate the switching pulse frequency based on the harmonic current value. The control module includes a calculation unit and a pulse generation unit. The calculation unit uses a cost function formula... The cost function values ​​of the zero vector and the effective vector are calculated, and the duty cycle of each vector is determined by the duty cycle formula d1=g0g2 / (g0g1+g1g2+g0g2). The pulse generation unit generates a 10kHz fixed frequency switching pulse according to the duty cycle.

[0009] The compensation module is used to output a compensation current according to the switching pulse frequency. The compensation module includes a commutation switch array and a STATCOM device. The commutation switch array uses IGBT modules to realize the commutation of three-phase loads. The STATCOM device outputs a compensation current through an L=2mH filter inductor and a C=2200μF DC capacitor to cancel the grid harmonic current.

[0010] The communication module is used to realize data interaction between the system and the backend. The communication module supports dual communication modes of RS485 and GPRS, and the communication delay is ≤50ms.

[0011] Preferably, the detection module further includes a deviation calculation unit, which is used to calculate the deviation between the reference voltage and the actual voltage using a PI regulator, and superimpose it with the harmonic current value to obtain the active current value. The proportional coefficient Kp of the PI regulator is 0.5 and the integral coefficient Ki is 0.1. The signal processing delay of the detection module is ≤200μs to meet the real-time compensation requirements.

[0012] Preferably, the calculation unit is further configured to use a power prediction formula. Calculate the predicted current value at the next moment, where R is the equivalent resistance of the circuit, taken as 0.1Ω, and T... s The sampling period is 100μs, L is the filter inductance value, and i c (k) represents the actual value of the compensation current at the current moment, v x For the target voltage vector, u s (k) represents the current grid-side voltage value.

[0013] Preferably, the commutation triggering condition of the commutation switch array is: when the three-phase current imbalance on the grid side is >15%, the single-phase load is controlled to commutate to the phase with the smallest deviation, and the commutation time is ≤10ms.

[0014] Preferably, the DC-side voltage of the STATCOM device is maintained at 600V±5V, and the active power compensation value is adjusted by a PI regulator to maintain voltage stability.

[0015] Preferably, the control module further includes a fault protection unit for collecting STATCOM switch status, temperature and DC capacitor voltage, and triggering circuit breaker tripping protection when the temperature is >85℃ or the voltage is >650V.

[0016] Preferably, the communication module further includes an optical fiber interface for achieving electrical isolation between the control module and the primary circuit, with an isolation voltage ≥2000V.

[0017] Preferably, the comprehensive compensation efficiency of the compensation module is ≥95%, which can reduce the power grid harmonic current distortion rate from 25% to below 5%.

[0018] Preferably, the system further includes a data storage unit for storing at least one year of power grid operation data, supporting historical data query and trend analysis.

[0019] Preferably, in the cost function formula, α and β are the components of the two-phase stationary coordinate system after the CLARK transformation, i * This represents the current reference value, k+1 is the next sampling time, and i p This is the predicted current value.

[0020] This invention provides a comprehensive power management system for power distribution rooms. It has the following beneficial effects:

[0021] 1. This invention, through the coordinated compensation of a STATCOM device and a commutation switch, significantly reduces the grid harmonic current distortion rate, meeting national standards and effectively solving problems such as cable overheating and increased motor losses caused by harmonics. Simultaneously, the system significantly improves the power factor and substantially reduces active power loss, achieving unexpected energy-saving effects.

[0022] 2. This invention, through the combined control of a commutation switch and a STATCOM, can rapidly trigger commutation when the three-phase current of the power grid is unbalanced, reducing the three-phase imbalance to an extremely low level. This significantly improves transformer operating efficiency and greatly extends equipment lifespan. The control module has an extremely fast response speed, capable of tracking load changes in real time, and significantly reduces reactive power impact during the start-up and shutdown of nonlinear loads, avoiding the impact of power grid voltage fluctuations on precision equipment.

[0023] 3. The communication module in this invention supports multiple communication modes to ensure stable data interaction and achieves electrical isolation through a fiber optic interface. The fault protection unit monitors key parameters in real time and quickly triggers the protection mechanism in case of anomalies. Combined with real-time monitoring of the entire system, this significantly improves operational reliability and meets the requirements for continuous industrial operation. Attached Figure Description

[0024] Figure 1 This is a system flowchart of the present invention;

[0025] Figure 2 This is a unit system diagram of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example:

[0028] Please see the appendix Figure 1 - Appendix Figure 2 This invention provides a comprehensive power management system for a power distribution room, comprising:

[0029] The detection module is used to collect three-phase voltage, three-phase current and load-side current signals from the power grid side of the distribution room, and to perform coordinate transformation and filtering on the signals to obtain harmonic current values ​​and fundamental current values. The detection module includes a data acquisition unit, a Clark transformation unit, a Park transformation unit and a low-pass filter unit. The data acquisition unit uses a 16-bit ADC to collect the current signal in real time at a sampling frequency of 20kHz.

[0030] The control module is used to calculate the switching pulse frequency based on the harmonic current value. The control module includes a computation unit and a pulse generation unit. The computation unit uses a cost function formula... The cost function values ​​of the zero vector and the effective vector are calculated, and the duty cycle of each vector is determined by the duty cycle formula d1=g0g2 / (g0g1+g1g2+g0g2). The pulse generation unit generates a 10kHz fixed frequency switching pulse according to the duty cycle.

[0031] The compensation module is used to output compensation current according to the switching pulse frequency. The compensation module includes a commutation switch array and a STATCOM device. The commutation switch array uses IGBT modules to realize the commutation of three-phase loads. The STATCOM device outputs compensation current through an L=2mH filter inductor and a C=2200μF DC capacitor to cancel the grid harmonic current.

[0032] The communication module is used to realize data interaction between the system and the backend. The communication module supports RS485 and GPRS dual communication modes, and the communication delay is ≤50ms.

[0033] Specifically, the data acquisition unit uses a 16-bit ADC to sample the current signal at a high frequency of 20kHz, achieving extremely high quantization accuracy and capturing minute current fluctuations below the 50th harmonic. The Clark transform unit converts the three-phase current into two-phase stationary coordinate system components, eliminating the influence of three-phase coupling. The Park transform unit further converts it into synchronous rotating coordinate system components, achieving separation of the fundamental wave and harmonics. The low-pass filter unit uses an 8th-order Butterworth filter with a cutoff frequency of 500Hz, keeping the harmonic extraction error at an extremely low level. The arithmetic unit evaluates the tracking error of each voltage vector to the current reference value using a cost function formula, and optimizes the three-phase PWM pulse width using a duty cycle formula, significantly reducing switching losses. The pulse generation unit uses digital phase-locked loop technology to ensure extremely high stability of the 10kHz pulse frequency. The commutation switch array consists of 6 high-performance IGBT modules, with extremely fast switching speed and support for high-current commutation. The STATCOM device uses an L=2mH iron-silicon-aluminum filter inductor and a C=2200μF electrolytic capacitor to form a second-order low-pass filter network with a cutoff frequency of 720Hz and extremely short harmonic compensation delay.

[0034] The detection module also includes a deviation calculation unit, which uses a PI regulator to calculate the deviation between the reference voltage and the actual voltage, and superimposes it with the harmonic current value to obtain the active current value. The proportional coefficient Kp of the PI regulator is 0.5 and the integral coefficient Ki is 0.1. The signal processing delay of the detection module is ≤200μs, which meets the real-time compensation requirements.

[0035] Specifically, the values ​​of the proportional coefficient Kp = 0.5 and the integral coefficient Ki = 0.1 are designed based on the root locus method. When the grid voltage fluctuates, the voltage deviation adjustment time is extremely short and the overshoot is minimal. The deviation calculation unit superimposes the voltage deviation and the harmonic current value, and generates an active current command through a feedforward compensation algorithm, so that the fundamental current tracking error is minimal and the signal processing delay of the detection module is extremely short, meeting the real-time requirements of STATCOM dynamic compensation.

[0036] The computing unit is also used to predict power consumption using the formula. Calculate the predicted current value at the next moment, where R is the equivalent resistance of the circuit, taken as 0.1Ω, and T... s The sampling period is 100μs, L is the filter inductance value, and i c (k) represents the actual value of the compensation current at the current moment, v x For the target voltage vector, u s (k) represents the current grid-side voltage value;

[0037] Specifically, the power prediction formula is derived based on the circuit state-space equation, where R = 0.1Ω is the sum of the equivalent internal resistance of the STATCOM and the line resistance, L = 2mH is the filter inductance, and the sampling period T_s = 100μs. This model can predict the compensation current for the next sampling period, with the prediction error controlled within a very small range. The computing unit updates the circuit parameters periodically and corrects the prediction model through the Kalman filter algorithm. When nonlinear loads start and stop, the current prediction accuracy is greatly improved.

[0038] The commutation triggering condition for the commutation switch array is: when the three-phase current imbalance on the grid side is >15%, the single-phase load is controlled to commutate to the phase with the smallest deviation, and the commutation time is ≤10ms;

[0039] Specifically, the three-phase current imbalance is calculated using a formula, and commutation is triggered when it exceeds a set threshold. This threshold is based on relevant standards and can prevent the transformer zero-sequence current from exceeding the rated value by a relatively low proportion. The commutation logic prioritizes the phase with the smallest current deviation and completes the load commutation in a very short time through bidirectional thyristor zero-voltage switching technology. The voltage sag during the commutation process is minimal, ensuring the normal operation of sensitive equipment such as frequency converters.

[0040] The DC-side voltage of the STATCOM device is maintained at 600V±5V, and the active power compensation value is adjusted by a PI regulator to maintain voltage stability.

[0041] Specifically, the DC side voltage is maintained at 600V±5V, keeping a reasonable voltage difference with the peak voltage of the 400V grid line, ensuring that the STATCOM inverter is in the linear modulation region and avoiding harmonic amplification caused by over-modulation; the 2200μF capacitors are configured in a 6-series 2-parallel configuration with a rated voltage of 650V, and the ripple current meets the operating requirements. When the voltage exceeds the set range, the PI regulator outputs a corresponding active current command, and the STATCOM absorbs or injects active power, resulting in fast regulation speed and extremely short voltage stabilization time.

[0042] The control module also includes a fault protection unit, which is used to collect the status of the STATCOM switch, temperature and DC capacitor voltage, and trigger the circuit breaker tripping protection when the temperature is >85℃ or the voltage is >650V.

[0043] The communication module also includes a fiber optic interface for electrical isolation between the control module and the primary circuit, with an isolation voltage ≥2000V;

[0044] Specifically, fiber optic transceivers are used, and the isolation voltage meets the requirements for enhanced insulation. The fiber optic medium is 62.5 / 125μm multimode fiber, which has a long transmission distance, low signal attenuation, and strong anti-electromagnetic interference capability. The RS485 link is used for local monitoring, and the GPRS link is used for remote data transmission, with extremely short communication latency. When the RS485 fails, it automatically switches to GPRS mode to ensure that no data is lost.

[0045] The overall compensation efficiency of the compensation module is ≥95%, which can reduce the power grid harmonic current distortion rate from 25% to below 5%.

[0046] Specifically, actual measurements of the 400V integrated filter power distribution room showed that the total distortion rate was at a high level before the treatment; after the treatment, the harmonics were significantly reduced, meeting the relevant standards, the cable temperature dropped significantly, and the copper loss of the motor was greatly reduced.

[0047] The system also includes a data storage unit for storing at least one year of power grid operation data, supporting historical data query and trend analysis;

[0048] Specifically, it adopts a 1TB industrial-grade SSD, supporting both local storage and cloud backup modes; data is sampled at the minute level, and can store ≥1 year of data, with extremely high storage space utilization; it has a built-in trend analysis algorithm that automatically generates change curves for parameters such as harmonic distortion rate and power factor; it supports abnormal data marking, providing data support for equipment maintenance and significantly improving maintenance efficiency.

[0049] In the cost function formula, α and β are the components of the two-phase stationary coordinate system after the CLARK transformation, and i * This represents the current reference value, k+1 is the next sampling time, and i p This is the predicted current value.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A comprehensive power management system for a power distribution room, characterized in that, include: The detection module is used to collect three-phase voltage, three-phase current and load-side current signals from the power grid side of the distribution room, and to perform coordinate transformation and filtering on the signals to obtain harmonic current values ​​and fundamental current values. The detection module includes a data acquisition unit, a Clark transformation unit, a Park transformation unit and a low-pass filter unit. The data acquisition unit uses a 16-bit ADC to collect the current signal in real time at a sampling frequency of 20kHz. The control module is used to calculate the switching pulse frequency based on the harmonic current value. The control module includes a calculation unit and a pulse generation unit. The calculation unit uses a cost function formula... The cost function values ​​of the zero vector and the effective vector are calculated, and the duty cycle of each vector is determined by the duty cycle formula d1=g0g2 / (g0g1+g1g2+g0g2). The pulse generation unit generates a 10kHz fixed frequency switching pulse according to the duty cycle. The compensation module is used to output a compensation current according to the switching pulse frequency. The compensation module includes a commutation switch array and a STATCOM device. The commutation switch array uses IGBT modules to realize the commutation of three-phase loads. The STATCOM device outputs a compensation current through an L=2mH filter inductor and a C=2200μF DC capacitor to cancel the grid harmonic current. The communication module is used to realize data interaction between the system and the backend. The communication module supports dual communication modes of RS485 and GPRS, and the communication delay is ≤50ms.

2. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The detection module also includes a deviation calculation unit, which is used to calculate the deviation between the reference voltage and the actual voltage using a PI regulator, and then superimpose it with the harmonic current value to obtain the active current value. The proportional coefficient Kp of the PI regulator is 0.5 and the integral coefficient Ki is 0.

1. The signal processing delay of the detection module is ≤200μs to meet the real-time compensation requirements.

3. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The computing unit is also used to predict power consumption using a power prediction formula. Calculate the predicted current value at the next moment, where R is the equivalent resistance of the circuit, taken as 0.1Ω, and T... s The sampling period is 100μs, L is the filter inductance value, and i c (k) represents the actual value of the compensation current at the current moment, v x For the target voltage vector, u s (k) represents the current grid-side voltage value.

4. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The commutation triggering condition of the commutation switch array is as follows: when the three-phase current imbalance on the grid side is greater than 15%, the single-phase load is controlled to commutate to the phase with the smallest deviation, and the commutation time is ≤10ms.

5. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The DC-side voltage of the STATCOM device is maintained at 600V±5V, and the active power compensation value is adjusted by a PI regulator to maintain voltage stability.

6. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The control module also includes a fault protection unit, which is used to collect the STATCOM switch status, temperature and DC capacitor voltage, and trigger the circuit breaker tripping protection when the temperature is >85℃ or the voltage is >650V.

7. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The communication module also includes an optical fiber interface for electrical isolation between the control module and the primary circuit, with an isolation voltage ≥2000V.

8. The power distribution room comprehensive energy management system according to claim 1, characterized in that, The comprehensive compensation efficiency of the compensation module is ≥95%, which can reduce the power grid harmonic current distortion rate from 25% to below 5%.

9. A comprehensive power management system for a power distribution room according to claim 1, characterized in that, The system also includes a data storage unit for storing at least one year of power grid operation data, supporting historical data query and trend analysis.

10. A comprehensive power management system for a power distribution room according to claim 1, characterized in that, In the cost function formula, α and β are the components of the two-phase stationary coordinate system after the CLARK transformation, and i * This represents the current reference value, k+1 is the next sampling time, and i p This is the predicted current value.

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