CN-121709392-B - Low-loss intelligent transformer system and transformer for light-load operation energy-saving optimization

CN121709392BCN 121709392 BCN121709392 BCN 121709392BCN-121709392-B

Abstract

The invention relates to a low-loss intelligent transformer system and a transformer for light-load operation energy-saving optimization. The system comprises a transformer body, an auxiliary excitation winding, a light load identification module and a magnetic excitation control module. When the transformer is detected to be in a light load state, the control module periodically injects excitation pulse signals with low amplitude and short time width into the auxiliary excitation winding so as to break the state that the magnetic flux of the iron core stays in a low magnetic density region of the hysteresis loop for a long time, improve the response linearity of the magnetic flux, inhibit harmonic distortion and improve the light load operation efficiency. The system adopts independent structural design, has small duty ratio and low energy consumption, has control closed loop, self-adaptive exit and transformation compatibility, and is suitable for new-installation and refitted energy-saving distribution transformers.

Inventors

WANG HENGYONG
SU HUANMING
HU HAOWEI
CHEN JIAN
ZHENG YIHANG
GAO RUI
XIE ZHENHUA
HUANG YONG
Xue Shuheng
HUANG YUANBIN
LIU ZHICHENG
XUE HONGDA

Assignees

福建铭博电气设备有限公司

Dates

Publication Date: 20260512
Application Date: 20260213

Claims (10)

1. The utility model provides a low-loss intelligent transformer system towards energy-conserving optimization of light load operation, includes transformer body, light load identification module, the transformer body has iron core, primary winding and secondary winding, its characterized in that: the transformer also comprises an auxiliary excitation winding which is completely electromagnetically isolated from the primary winding and the secondary winding, and a magnetic excitation control module which adopts an independent packaging structure with the transformer body; The auxiliary excitation winding is attached and fixed on a magnetic flux path of an iron core supporting leg of the transformer body, shares the same iron core magnetic circuit of the transformer body with a primary winding and a secondary winding, can be installed without disassembling the primary winding and the secondary primary winding, and adapts to energy-saving modification of the stock transformer, wherein the number of turns of the auxiliary excitation winding is 100-200, the diameter of a wire is 0.3-0.5 mm, and the insulation grade is not lower than the grade F; The light load identification module is provided with a current transformer, acquires a secondary side output current signal of the transformer in real time in a fixed sampling period of 1-5 seconds, performs stable light load judgment through a sliding time window after performing moving average or median filtering treatment on the acquired current signal, and sends an excitation enabling signal to the magnetic excitation control module when the continuously sampled output current is lower than 10% -20% of the rated output current of the transformer and the accumulated duration of a low current state reaches 300-600 seconds; The magnetic excitation control module is electrically connected with the auxiliary excitation winding through a quick connector and comprises a micro control unit, a PWM control circuit, an isolation driving circuit, a power switch module and a zero-crossing synchronization unit; when the starting operation, the output voltage of the transformer is detected through a zero-crossing synchronous unit, when the voltage is detected to be near a zero crossing point and the voltage change rate approaches zero, the power switch module is triggered by delaying 1-3 ms, an excitation pulse signal is periodically applied to an auxiliary excitation winding, and the auxiliary excitation winding introduces periodic micro-amplitude magnetic flux disturbance to the iron core to forcedly break the magnetic domain pinning state of the iron core magnetic flux in a low magnetic density region of a hysteresis loop for a long time, so that the magnetic flux working point of the iron core returns to a linear response region of the hysteresis loop, the hysteresis distortion and the smooth magnetic flux change are weakened, and the iron loss and the total harmonic distortion rate of the output current of the transformer light load operation are reduced; the excitation pulse signal output by the magnetic excitation control module is a bidirectional sawtooth wave or a positive and negative symmetrical square wave, the frequency is 0.2-1 Hz, the duty ratio is less than 5%, the pulse width is 3-10 ms, and the peak voltage is 12-24V.
2. The system of claim 1, wherein the auxiliary excitation winding is wound around a non-main winding leg region of the core, and the dc resistance is 10-30 Ω to minimize electromagnetic coupling interference with the main winding.
3. The system of claim 1, wherein two ends of the auxiliary excitation winding are connected in parallel with a passive magnetic energy release buffer branch, and the passive magnetic energy release buffer branch is formed by connecting an RC damping circuit and a unidirectional clamping fast recovery diode in series and is used for absorbing residual disturbance magnetic energy of an iron core after the excitation pulse is ended and inhibiting residual magnetic disturbance resonance.
4. The system of claim 3, wherein the RC damping circuit comprises a damping resistor and an energy-absorbing capacitor connected in series, the damping resistor has a resistance value of 10-50 Ω, the energy-absorbing capacitor has a capacitance value of 1-10 μF, the rated withstand voltage of the unidirectional clamp fast recovery diode is not lower than 100V, the reverse recovery time is less than 50ns, and the reverse leakage current is less than 10 μA.
5. The system of claim 1, wherein the magnetically activated control module is further provided with a forced exit protection unit that automatically pauses the activation process and enters a standby protection state when the activation pulses continue to run for more than a preset maximum on time of 30 minutes without triggering a load restoration.
6. A distribution transformer employing the low loss intelligent transformer system of any of claims 1-5.
7. A magnetic state reconciliation method of a low-loss intelligent transformer for light-load operation energy-saving optimization, applied to the system as claimed in claim 1, comprising the following steps: S1, accurately identifying a light load state, namely collecting secondary side output current of a transformer in real time in a fixed sampling period of 1-5 seconds, performing stable light load judgment through a sliding time window after carrying out moving average or median filtering treatment on collected current signals, and judging as a stable light load state when the continuously sampled output current is lower than 10% -20% of rated output current of the transformer and the accumulated duration of the low current state reaches 300-600 seconds; S2, excitation control triggering, namely after the steady-state light-load state is judged, the light-load identification module sends an excitation enabling signal to the magnetic excitation control module, the magnetic excitation control module wakes up from a dormant state, and the preset excitation pulse parameters are preloaded; S3, synchronous magnetic state tempering, namely detecting the output voltage of a transformer through a zero-crossing synchronous unit, and when the detected voltage is near a zero-crossing point and the voltage change rate approaches zero, triggering a power switch module by delaying 1-3 ms, periodically applying an excitation pulse signal to an auxiliary excitation winding, introducing periodic micro-amplitude magnetic flux disturbance into an iron core through the auxiliary excitation winding, forcibly breaking the magnetic domain pinning state that the magnetic flux of the iron core stays in a low magnetic density region of a hysteresis loop for a long time, enabling the working point of the magnetic flux of the iron core to return to a linear response region of the hysteresis loop, weakening hysteresis distortion and smooth magnetic flux change, and reducing the light load operation iron loss and the total harmonic distortion rate of output current of the transformer, wherein the excitation pulse signal is bidirectional sawtooth wave or positive-negative symmetrical square wave, the frequency is 0.2-1 Hz, the duty ratio is less than 5%, the pulse width is 3-10 ms, and the peak voltage is 12-24V; And S4, self-adaptive exit control, namely continuously monitoring a load state, immediately stopping excitation pulse output when the output current is recovered to be above a light load judgment threshold value and a hysteresis deviation threshold value of 2% -5% of rated current is overlapped, enabling the magnetic excitation control module to enter a dormant state, enabling the auxiliary excitation winding to stop working, and returning the transformer to a normal operation mode.
8. The method according to claim 7, wherein in step S3, after the excitation pulse is ended, the absorption and release of the residual disturbance magnetic energy of the iron core are completed within 10ms through the passive magnetic energy release buffer branches connected in parallel to the two ends of the auxiliary excitation winding, so as to inhibit the residual magnetic disturbance resonance.
9. The method of claim 7, wherein in step S4, when the excitation pulse is continuously operated for more than 30 minutes without triggering the load recovery, the system automatically pauses the excitation process, enters a standby protection state, and re-verifies the light load state after an interval of 10 minutes.
10. The method of claim 7, wherein in step S1, the system performs a light load threshold self-calibration procedure during a non-critical night load period, wherein a standard excitation pulse signal is injected into the auxiliary excitation winding, an induced voltage fallback characteristic of the auxiliary excitation winding is recovered, a core magnetic state response index is calculated, and a light load judgment current threshold is corrected in real time based on the magnetic state response index.

Description

Low-loss intelligent transformer system and transformer for light-load operation energy-saving optimization Technical Field The invention belongs to the technical field of transformers, and particularly relates to a low-loss intelligent transformer system and a transformer for light-load operation energy-saving optimization. Background Distribution transformers are critical energy conversion and distribution units in power systems, the operating efficiency of which directly affects the energy consumption level of the power supply system. In practical application, the running load of a transformer is significantly affected by the change of seasons, time periods and regional demands, and particularly in the scenes of urban buildings, industrial parks, data centers and the like, the phenomenon that the transformer is in a light load state far lower than rated load for a long time is common. The traditional energy-saving optimization method of the transformer is generally focused on the following aspects of selecting low-loss magnetic materials to reduce iron loss, realizing energy saving of an idle section through grouping windings or an automatic switching device, improving a winding wiring structure to improve thermal stability and the like. These strategies have been developed around three elements, "voltage-current-power", with the primary objective of reducing system power consumption or improving operating efficiency. However, under the light load state, there is a hidden problem that is widely ignored but has a substantial influence on the system performance, namely the hidden danger of 'low excitation saturation' caused by the magnetic density offset of the iron core. When the transformer operates under the working condition of light load or ultra light load for a long time, the current of the main winding is reduced, magnetomotive force is weakened, the average magnetic flux density born by the iron core is obviously reduced, and the working point of the transformer is close to a low excitation section (initial steep region) of the hysteresis loop. This region has unstable permeability change and enhanced hysteresis, and is likely to induce nonlinear distortion in magnetic flux response, so-called "low excitation saturation". This has the following consequences: the magnetic flux response hysteresis zone is enlarged, and the magnetic flux generated by the input current of the iron core does not linearly respond any more, so that the voltage regulation stability is affected; the current distortion is increased, the output current waveform which is originally stable under light load is distorted, the harmonic content is increased, and the electric energy quality is damaged; The system efficiency deteriorates, and the loss ratio of the unit output power increases instead, causing "inefficient operation", although the load is light; The iron core is abnormal in micro-local heating, local magnetic density is frequent in fluctuation, hot spot areas are easy to generate, and the service life of the iron core is influenced for a long time. The conventional technology mostly understands "magnetic saturation" as an upper limit problem under high load or strong excitation, and only care is taken to avoid the iron core from entering a saturated magnetic region (i.e. a high magnetic density region), but bad influence understanding of a low magnetic density region for a long time is insufficient. Especially under the automatic voltage regulation or no-load energy-saving control strategy, the problem of low excitation is often misjudged as 'light load, low loss and no intervention', so that a corresponding recognition and compensation mechanism is lacked. With the development of energy-saving power grids and distributed power distribution systems, the transformers running under light load for a long time are increasingly more and more common in the 'recessive hysteresis distortion' problem in the system, and even the harmonic filter is interfered when serious, the power factor compensation precision is affected, so that the transformer becomes a non-dominant bottleneck for restricting the high-quality running of the intelligent power grid. Therefore, a transformer energy-saving operation mechanism capable of actively regulating the magnetic state of the iron core under the light load condition and getting rid of a low-excitation nonlinear hysteresis zone is needed, so that the iron core is always in a magnetic flux response optimal zone, and the system efficiency and the electric energy quality are improved from the magnetic response angle. Disclosure of Invention The invention aims to provide the low-loss intelligent transformer system and the transformer for optimizing the light-load operation energy conservation, which not only fundamentally solve the problem of magnetic state imbalance of the iron core under the light-load operation of the transformer, but also give consideration to the energy conservation effec