Application of intelligent integrated power capacitor in a green material manufacturing plant in Shandong

Ren Yunye Ankerui Microgrid Jiangsu Jiangyin 202207 Abstract: Analyze the working principle and function of intelligent integrated power capacitors, combine the current situation of power distribution in Shandong Environmental Protection Material Manufacturing Plant, select an economical and reliable solution, intelligent capacitor zero switching and low power consumption, and solve the problem of inrush current generated by relay cutting; Simple wiring, convenient expansion, to solve the problem of insufficient space in the reactive power compensation cabinet and insufficient compensation capacity; With the communication function, it can be transmitted to the background, which solves the problem
of compensating the decentralized management of power distribution and failing to alarm in time.

Keywords: low-voltage intelligent power capacitor, reactive power compensation, power factor 0 overview For the power supply part of the power system, the generator that provides electrical energy is designed according to the required rated voltage and rated current, and the generator is in long-term operation, the voltage and current cannot exceed the rated value, otherwise it will shorten its service life and even damage the generator
.

Since the generator is rated by the product of rated current and rated voltage, this means that when its input load is resistor, the generator is theoretically fully utilized, because the cosφ in P=UIcosφ = 1; but when the load is inductive or capacitive, cosφ<1, the generator is not fully utilized
.

In order to use the capacity of the generator, that is, the generator produces a large amount of power, it is necessary to improve its power factor
.

In the low-voltage power distribution system, the use of shunt capacitor devices to compensate the reactive power centrally or in situ compensation is an effective way
to reduce line loss and save power.

The main effect of reactive power compensation is: reducing the power loss of equipment and lines; Stabilize voltage and improve power supply quality; Improve the carrying capacity of power transformers; In long-distance transmission, improve the transmission stability and transmission capacity of the
system.

Traditional capacitor reactance reactive power compensation device, low compensation accuracy, single function, complex installation and wiring, while not conducive to production, transportation, installation, commissioning and reliable operation, has seriously restricted its development, capacitors in the pitching process is easy to produce a large impact current, causing the grid overvoltage, serious will produce harmonics, the stability of the power grid has an impact
.

In order to solve these problems, a low-voltage intelligent integrated power capacitor with zero-crossing switching technology can be used as a compensation device
instead.

1.
Principle analysis AZCL intelligent integrated harmonic suppression power capacitor with co-supplementary capacitor or sub-supplementary capacitor as the main body, using micro electronic component technology, micro sensor technology, micro network technology and electrical appliance manufacturing technology, the intelligent components, controllers, capacitors, reactors, plastic shell circuit breakers and other components miniaturized, the whole machine is small in size, exquisite
in structure.

Intelligent capacitor controller through the current transformer, voltage sampling to calculate the reactive power deficit, power factor and other parameters, with industrial-grade MCU as the core, with AD conversion, RS-485 communication, LCD display, data storage, etc.
constitute a system, set acquisition, calculation, analysis, control, communication, human-computer interaction, data storage in one
.

1.
1 Intelligent network control function
.

Automatically detects and tracks reactive power changes in the system and automatically switches capacitor banks
.

The switching method is: capacitors with the same capacity, according to the principle of cyclic switching; Capacitors with different capacities are switched according to the principle of adaptation; Shoot first, cut first, back first, throw
first.

When the compensation condition is constant, the capacitor is cyclically switched once every hour, avoiding the long-term operation
of a single capacitor.

1.
2 Fast switching capacitor function switching switch selection composite switch, no contact zero switching, with the dedicated intelligent capacitor reactive power compensation controller, the action time is shortened to 1s, the dynamic tracking compensation system is missing reactive power, and strive to reduce the line loss to a lower level
.

The composite switching circuit includes thyristor zero-crossing detection and trigger module, thyristor protection module, and magnetically held relay drive module
.

The circuit adopts the composite technology of power electronic thyristor and high-power magnetically holding relay, which uses the fast conduction of thyristor and the zero voltage drop of the magnetic-holding relay contact to achieve complementarity, and truly achieves zero-crossing switching and low-power operation
.

When closing, the circuit detects the voltage difference between the two ends of the thyristor in real time, and when the voltage difference is basically 0, the thyristor is triggered on, without impact inrush current, and flexible input; After stabilization, the magnetically held relay is supplied, and the two ends of the short-circuit thyristor electrodes are connected to the main loop through the relay contacts, reducing the switching voltage drop, while the relay contacts are maintained through the positioning of the permanent magnet element to further reduce power consumption
.

1.
3 The measurement function can measure the system voltage, current, frequency, active power, reactive power and power factor and other electrical parameters, and can also detect the voltage and current harmonics of each time, and view the power grid parameters
in real time.

1.
4 Phase compensation function Phase type capacitor can switch the capacitors on each phase separately, improve the accuracy of the compensation of the reactive power of the system, so that the three-phase reactive power imbalance system has been well compensated
.

1.
5 Protection function capacitor has overvoltage, undervoltage, undercurrent, over-temperature, phase-off, over-harmonic protection
.

When the internal temperature of the capacitor exceeds 60°C, the capacitor will be withdrawn from operation to ensure the safety of
the system.

1.
6 The communication function capacitor and the controller are connected by network cable, and the controller and the background are connected by RS485, which facilitates a large number of data collection, upload data and exchange information with peripheral monitoring terminals, which constitutes system work
.

1.
7 The harmonic suppression function connects the reactor and the capacitor in series to form an LC loop, reducing the distortion of the harmonic, and for harmonics higher than the self-resonant frequency of the LC loop, it is inductive and avoids resonance
.

The 7% reactor can effectively suppress more than 5 or 7 harmonics, preventing the occurrence
of unfavorable factors such as overheating of the capacitor, aging of the insulation medium and degradation of self-healing performance.

2.
On-site case: A certain environmental protection material manufacturing plant in Shandong, mainly engaged in imitation wood decorations, imitation wood wire products, picture frames, photo frames, etc.
, covers an area of 142 acres, mainly including factories, office buildings, exhibition halls, canteens, staff dormitories, etc
.

Its power distribution system is composed of several 10/0.
4KV main transformers, which supply power
to the power equipment through low-voltage distribution equipment.

Workshop transformer capacity of 1600kva, the total load capacity of 1020kw, the current power factor of 0.
8, to increase the power factor to about 0.
95, its main load for the heating furnace, motor, etc.
, load harmonics to 5, 7 times the main, the choice of 7% intelligent capacitor; Office building transformer 1250kva, the total load capacity of 650kw, the current power factor of 0.
75, its main load for switching power supply, lighting, etc.
, harmonics to 3 harmonics mainly, the choice of 14% intelligent capacitor
.

Figure 1 Workshop power distribution diagram Figure 2 Office building power distribution figure 3, the solution plant workshop of the low-voltage distribution system is mainly a three-phase load heating furnace, motor, mainly causing 5, 7 harmonics, the use of 7% reactance for tuning treatment, protect the capacitor from harmonics to amplify the current
.

The installed capacity is 600kvar, and the total compensation and 7% intelligent capacitor are selected, and the compensation power factor reaches about 0.
95 to meet customer requirements
.

Using ordinary capacitive reactance, at least two sets of cabinets with a width of 1000 * depth of 1000, now install AZCL intelligent integrated harmonic suppression power capacitors, only need two sets of cabinets with a width of 800 * depth of 800, cabinet space is also greatly saved, wiring is simple, easy to install, higher
reliability.

The low-voltage distribution system of the office building has a large number of harmonic source loads, which will produce 3, 5, 7 harmonics, and a large number of single-phase nonlinear loads will cause three-phase imbalance, harmonic exceedance, neutral line harmonic overload and other power quality problems, and the impact of
harmonics should be considered for reactive power compensation.

Calculated reactive power demand of 350kvar, installed capacity of 480kvar, taking into account the harmonics with the system, the installation of a total of 300kvar, 180kvar capacity of 14% intelligent capacitor, the actual power factor reached 0.
94, in line with the requirements, the use of ordinary capacitor reactance, at least two sets of cabinets wide 1000 * deep 1000, now install AZCL intelligent integrated harmonic suppression power capacitors, only two sets of wide 800* * * The cabinet with a depth of 800 is also greatly saved, the wiring is simple, the installation is convenient, and the reliability is higher
.

4.
AZCL Intelligent Integrated Harmonic Suppression Power Capacitor 4.
1 Overview AZCL Intelligent Integrated Harmonic Suppression Power Capacitor is a new generation of reactive power compensation equipment used in 0.
4kV, 50Hz low-voltage power distribution to save energy, reduce line loss, improve power factor and power quality
。
It is composed
of intelligent measurement and control unit, thyristor composite switching circuit, line protection unit, capacitor and reactor.

AZCL low-voltage intelligent power capacitor adopts customized segmental LCD liquid crystal display, which can display three-phase bus voltage, three-phase bus current, three-phase power factor, frequency, capacitor path number and switching state, active power, reactive power, total distortion rate of harmonic voltage, capacitor temperature, etc
.

Through the internal thyristor composite switch circuit, it automatically finds the input (resection) point to achieve zero-crossing switching and has protection functions
such as overvoltage protection, phase loss protection, overharmonic protection, and over-temperature protection.

4.
2 Technical parameters 4.
3 Wiring method 5, Conclusion In the project of Shandong Environmental Protection Material Manufacturing Plant, the power factor is generally low, the electricity fee is fined, and the power capacitor is used to suppress the power capacitor to emit reactive power, improve the voltage level of the receiving bus bus, reduce the output of the inductive reactive power on the line, reduce the voltage and power loss, and thus improve the transmission capacity
of the line.

AZCL intelligent integrated harmonic suppression power capacitors are simple to operate and fully functional, which can effectively solve user problems and achieve energy-saving effects
.

Whether it is from the perspective of economy or practicality, it has a wide range of promotion value
.

The power grid produces both active and reactive power, and the reactive power will have losses in the transmission process of the power grid, and the low-voltage intelligent power capacitor performs reactive power compensation, thereby improving the power factor, effectively improving the quality of electricity, saving electricity costs, reducing the cost of enterprises, reducing the loss of lines, and improving the efficiency
of power grid transmission.

6.
Reference[1] Handbook of Enterprise Microgrid Design and Application.
2020.
6[2] Yadong Liu, Yabin Xue.
Research and design of low-voltage intelligent capacitors based on DSP[J].
Electrotechnical Technology,2018,1(Part 2):7,9[3] Wang Zhaoan, Liu Jinjun, Wang Yue, et al.
Harmonic suppression and reactive power compensation[M].
Di 3 version.
Beijing:China Machine Press.
2015[4] Guo Guofang.
Application of reactive power compensation in urban distribution network[J], Power Grid Technology, 2007, 31 (S1): 229, 2307, the author introduces Ren Yunye, male, currently working at Acquaray Microgrid Research Institute, the main research direction is the application
of ordinary capacitors, smart capacitors and other power quality products.