Big how to improve PV inverter yield

Polaris solar PV net news: photovoltaic power plant yields all power investors, generating companies has always been most concerned about the topic, and yields a lot of factors affect PV power station, including initial investment costs, operation and maintenance costs of late, power generating capacity. From inverter-side considerations, factors affecting yields of inverter installation and maintenance, initial construction investment, capacity, reliability, and so on.

Various inverter manufacturers in recent years through constant research and innovation, launched several more advanced technology of grid-connected photovoltaic inverter to meet customer requirements for high yields. TC500KH as a new generation of tebian electric inverter products through comprehensive upgrading of the structure of hardware and software, optimization, the highest conversion efficiencies as high as 98.7%, European efficiency efficiency reached up to 98.4%,MPPT tracking 99.5% (dynamic) and 99.9% (static), and power density of up to 277W/kg, with strong competitiveness in the market.

TC500KH effect diagram

A, 98.7% TC500KH to achieve the conversion efficiency?

The factors affecting the conversion efficiency of the inverter consists mainly of two parts: hardware and software factors, major hardware factors by reactance losses, power loss, filter loss of cooling fan of three parts, while the software mainly under the influence of modulation algorithms.

(1) how to reduce the power loss?

Power device is the photovoltaic array output conversion of direct current into alternating current of the important part is the core of the inverter, that part of the loss accounted for the largest proportion of the total loss of the inverter, and reduce the loss of that part of the whole inverter conversion efficiency is greatly enhanced.

A.-uses the latest generation of NPT IGBT

NPT IGBT is a non-penetrating-type single Crystal Semiconductor power devices, the device compared to traditional PT-IGBT devices with low switching loss, high temperature characteristics. Photo of PT-IGBT and NPT IGBT turn-off waveform, evident of NPT IGBT switching losses than the PT-IGBT.

PT-IGBT turn-off waveform type NPT IGBT turn-off waveform

B … using MSL SVPWM algorithm

SVPWM algorithm of minimum switching losses that switches per phase in a cycle of 120 degrees, the total effective switches reduce the number one-third, power device in the current positive and negative peak area is not to make inverter full load loss reduces 1400W, effectively reduce the power loss.

Traditional SVPWM strategy of MSL SVPWM modulation strategies

(2) how to reduce the loss of filter reactor?

Filter reactor power devices convert the output square wave to sine wave function is to protect an important part of inverter output power quality. TC500KH grid-connected inverter using LCL filter design have better high frequency attenuation characteristics. Relative to the l-shaped filters, more total inductance is small, relative to the LC filter in three-phase grid-connected systems, filter for better power quality even higher.

Filter reactor loss is mainly composed of iron loss and copper loss and stray losses in composition, iron loss associated with the quality and quantity of silicon steel sheet; copper winding and winding technology and current related to stray losses associated with the leakage inductance and lower core loss, to reduce the reactor’s loss, enhance the efficiency of inverters have a clear role. So the design of the new type reactor with integrated Magnetics technology was successfully applied to the inverter, the reactor is to conjugate both inductors designed to offset part of the yoke magnetic circuit, reduce the amount of silicon steel sheet, reducing reactor core loss, improving reactor efficiency.

Conjugate reactor design

Reactor compared before and after optimization:

(3) how to reduce the loss of cooling fan

Cooling fan, responsible for the internal heating device ventilation of the inverter function, is an important element of guarantee stable operation of the inverter, the loss of cooling fan also was part of the inverter cannot be ignored in the total loss.

First, in order to reduce the loss of cooling fan to start with fan selection, select low power consumption, brand and the cooling fan with speed control function is one of the most effective ways to reduce losses, but lower power consumption of cooling fan will also bring problems not to be ignored-the exhaust volume decrease. Use of optimized for minimal loss of fan cooling function and design of the components of the structure and air duct must be reasonable. After a series of optimized design, with intelligent speed low-power cooling fan feature is applied to inverter, the power consumption of only 450W, compared with constant speed fan to reduce the consumption of 44%, reducing the cooling system power consumption at the same time, protects the inverter heat sink reliability.

Second, how TC500KH with ultra high reliability?

(1) reliability thermal design

TC500KH with front air intake, high wind at the back of the radiator model, based on reasonable layout of all components and temperature resistant, buoyancy effect using fluid inertia and negative pressure, to scientific triage cold air so all power devices meet strict temperature Derating using standard, greatly enhanced efficiency and ensure long-term stable operation.

By at an ambient temperature of 50 ° c, elevation after thermal simulation 3000m is evident, the superiority of TC500KH cooling system design, the core component IGBT temperature did not exceed 100 ° c (IGBT maximum permissible conductor temperature is 175 degrees c).

Inverter inverter temperature field and velocity field

(2) design of reliable protection

A … Cabinet surface protection of design

Protective design, mainly from outside the shell of the Cabinet starting with the selection of materials and surface treatments, TC500KH grid-connected inverters the shell was assembled by using high quality galvanized plate, Cabinet surface using electrostatic powder coating treatment, higher compared with ordinary cold rolled steel corrosion resistance, strength, to resist the invasion of sand.

B. Cabinet inlet protection design

NET as the most direct protection of the inverter device, protective effect on the Cabinet plays an important role. TC500KH grid-connected inverter is equipped with double-layer dust-proof net at the inlet, can effectively prevent dust from entering the inside of the Cabinet, protects internal components from dust-covered.

C. slot of the cabinet design

Cabinet slot handling is very important for the protective properties of the machine, usually cracks occurred mainly in the door area. TC500KH grid-connected inverters in order to guarantee internal duct sealing, rear and sides of the Cabinet using a closed design prevents dust from door panel gaps to enter the Cabinet. In addition, the Cabinet exterior frame edge flanging, inside of the door edges with sealing foam, when the door is closed, the foam and flanged fitting, dirt unable to crack into the door.

Location of sealing foam

D. control protection design

Inverter controlled mainly by the PCBA components, this part of poor tolerance to dust, require more stringent protective treatment. First of all, TC500KH by partially encapsulated within the control of the inverter module, to provide perimeter protection. Secondly, twice three-proof coating processing of circuit board, and helps protect the Board from dust erosion. Three-proofing lacquer has good resistance to high and low temperature performance, which form a transparent protective film after curing, excellent insulation, moisture-proof and leakage-proof, shock-proof, dustproof, corrosion-proof, anti-aging, Corona and other properties.

Three anti-paint coating effect chart

(3) reliable high altitude design

Effects of altitude on electric equipment mainly in three aspects: ① low temperature electronics condition bad; II the low air pressure, electrical insulation affected; and aim at thin air, heat dissipation conditions are poor. In order to protect the inverter to run reliable at high altitude, the design should fully consider the impact of these three aspects to the inverter.

Low temperature: low ambient temperature in high elevation areas, and some areas temperatures below-40 ° c, seriously affecting the operating reliability of electronic devices. TC500KH grid-connected inverter through the heater inside the inverter configuration, can quickly upgrade the Cabinet internal temperature to a reasonable extent, ensure that the inverter is capable of reliable operation at low temperatures.

Air pressure: air pressure will cause the breakdown voltage of the electrical clearance decreased affect insulation of electrical equipment, and increase their possibilities of high voltage breakdown. TC500KH grid-connected inverter properly in accordance with the design standards at high altitude, the electrical space according to a standard design of elevation of 1.5 times more than double.

Thin air: the air density decreases in the thin air, cause the inverter cooling conditions will worsen. TC500KH in the design of the inverter when considering the effects of altitude, through thermal simulation and experiments, optimizing the layout of the heating device in air duct, in addition, to optimize the heat sink, cooling fan design to meet at 3000m, under ambient temperatures of 50 degrees centigrade, will still be able to full power operation of the inverter.

Third, TC500KH how to reduce the power plant construction investment?

TC500KH as a high power density of the inverter, only 1500mmx2150mmx850mm machine size (width x height x depth), the space is small, it can effectively reduce the inverter area reduces inverter room construction investment, for lower power stations initial construction costs, is of great significance.

Four, TC500KH how to reduce the operation cost?

TC500KH fully taken into account in the design of the inverter to the power plant maintenance effect of electricity on the spot, thereby optimizing the layout of the inverter. By cooling fan, control systems, such as three-phase IGBT packaged as separate modules, fault localization, operation and maintenance personnel Strip failure module can be replaced, a single module replacement for no more than 20 minutes, minimizes the impact of equipment failures on electricity.

Modular former maintenance

Five, the summary

PV inverter as the core power generation equipment, to improve the yields of the plant as a whole plays a vital role. Adopted with high efficiency, high reliability, high power density, and maintainability of grid-connected inverters can provide higher capacity benefits to users, less investment and lower maintenance costs for PV power plant yields escort.

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