Abstract and required for the design requirements of the grid. Take a voltage source inverter design of photovoltaic power generation and network operation, and 16 micro-disposal device and IGBT power devices improved inverter output waveform.
Introduction
solar photovoltaic power generation system is important for electricity or power shortages in remote geographical broken as independent power to power household appliances and lighting fixtures. Followed by electricity relaxation environment Contagion increasingly significant, with the utility grid and grid solar power system has been showing increasing competitiveness. Photovoltaic power generation and network operation will be omitted aspects of energy storage - batteries alone break photovoltaic system, thus greatly reducing the protection of the power station. Shorter battery life, eliminating the need for batteries, the life of the power generation system commensurate with the life of the solar cell. Family residential equipment photovoltaic power generation system, flaccid daytime electricity to ease the situation, the progress grid power factors and decreased line losses. Photovoltaic power plants and power generation, the ultimate will replace the customary energy generation. Photovoltaic power generation grid shown in Figure 1. The solar array power passed to the grid by the sinusoidal pulse width modulation inverter, the inverter to feed electricity sent to the grid resolution array power and local sunshine conditions. Inverter with DC - AC conversion function, but also must have the maximum power of the PV array tracking efficacy and various maintenance functions. The inverter shown in Figure 1 of the voltage-type inverter,power inverter. Voltage source inverter skills matured, the hardware required
bought easily. This article will voltage source inverter for further discussion.
1 small photovoltaic grid power stations should have the function
PV power plant and network operation, put forward higher requirements for the inverter. These requirements are as follows
ㄧ request the inverter output sinusoidal current. PV power plant back to the utility grid power required satisfaction grid-delineated indicators, such as the output of the inverter current can not contain a DC component and the high harmonics of the inverter output current is necessary to minimize, on the grid can not cause harmonic infection and so on.
ㄨ requirements of the inverter in the efficient operation of the larger case load and sunshine variations can. Energy from solar photovoltaic power plants, sunshine intensity meteorological changes, which requires the inverter in the sunshine under the premise can efficient operation.
The inverter enables
ㄩ request photovoltaic arrays work at the maximum power point. The power output of the solar cell is related to changes in sunshine, temperature, load, output characteristics with non-linear characteristics [1]. This requires an inverter efficacy of the maximum power point tracking, that no matter how the sunshine, temperature change can take the initiative to adjust to achieve the best run of the array through the inverter.
inverter using small size, solid advanced features. Household photovoltaic power plants, of its inverter usually installed in the indoor or wall hanging on the wall, both its volume, component limits. In addition, the robustness of the whole machine is also put forward higher requirements. Solar battery life of 20 years, the life of its accessory equipment must also be its proportionate.
requirements in mains power inverter sunshine state may own supply.
2 sine wave voltage inverter implementation
photovoltaic grid run circuit shown in Figure 2. Up is the output voltage of the inverter, Uu for grid voltage, R is the line resistance, L series reactors, Iz compared feedback grid current. To protect the power factor of feedback, contribute to the current phase must be consistent with the phase of the grid voltage. The same phase reference grid voltage Uu, Iz with Uu, the vector shown in Figure 3. Resistance R two really consistent voltage UR and grid voltage phase the reactor voltage across UL phase is outdated UR90 ì thus able to obtain the phase and amplitude of the UP
where is the frequency of the utility grid angle. In the actual circuit, the phase, period, and amplitude of UU detected by a voltage sensor. Because R is difficult to obtain in practical systems, and thus the phase of the feedback current Iz must use the current negative feedback to achieve feedback the current Iz phase angle reference phase is the utility grid phase
bit. Readily detected with current transformers Iz, consistent ensure Iz with the grid voltage phase, in order to achieve a power factor of a feedback generation.
apply photovoltaic power grid to run dedicated inverter structure shown in Figure 4. Tube with IGBT inverter main circuit power capacity of 50A, the 600V model 2MBI50N-060. Driver circuit isolation produced by Toshiba TLP250. The inverter master the local microprocessor completed. Master chip INTEL latest inverter or motor drive dedicated 16 microprocessor 87C196MC, the chip in addition to a 16-bit instruction, also has a dedicated pulse width the
modulation (PWM) output port [2 contains a 10-bit A / D converter, an event processing array, two 16-bit timers, and a three-phase waveform generator. Each phase of the three-phase waveform generator can output two can be set to the death zone time PWM signal,Grid tie inverter.
which supply to inverter use spaces a lot. Microprocessor important to achieve the grid, real-time detection of the phase, current feedback phase restraint, the PV array maximum power point tracking and real-time sinusoidal pulse width modulation signal occurs, follows the course of their work to the utility grid voltage and phase through the Hall voltage sensor gave microprocessor 's A / D converter, the microprocessor will the phase of the feedback current in phase with the utility grid voltage for comparable sent to the PWM pulse width modulator, the error signal by the PID regulator, which completed the power factor of 1 of electricity feedback process. Microprocessor Another major task is to achieve the maximum power output of the PV array. The PV array output voltage and current resolution be detected and multiplied by the voltage, the electrical propagation sensor array output power, and then to adjust the duty cycle of the PWM output. This duty cycle regulation essentially is to regulate the the
feedback voltage size, in order to achieve maximum power optimization.
be noted from Figure 3, when the Up amplitude variation, feedback will also have a phase angle ヵ between the current and grid voltage must change. Has been achieved because the current phase feedback gripping, thus natural to achieve a decoupling of the phase and amplitude to master, so that the process of the microprocessor processing easier. In addition, the photovoltaic power generation and network operation must also be appropriate, the state utility grid outage. Practices photovoltaic grid system, the end of the inverter in the utility grid outage. Photovoltaic arrays during the day, it can still continue to generate electricity.
how it works when the utility grid power grid side commensurate short-circuit conditions, and network operation inverter will automatically cover overload. When the microprocessor detects the overload, in addition to closed SPWM signal, will disconnect the relay RE, if the PV array at this time energy output, the inverter will be in the running state run separately. When running alone restraint absolutely schematically, is the exchange of a negative feedback of the voltage condition, the microprocessor by detecting the output voltage of the inverter and to be comparable with a reference voltage, usually 220V, and then gripping the duty cycle of the PWM output, the inverter and the regulator run . Of course, running alone conditions the PV array can supply enough power at the time. If the load is too big or poor sunshine premise, the inverter helpless output enough power, the terminal voltage of the PV array that will land, so that the output switch voltage drop into the low pressure to maintain state. When grid power is restored, http://www.gridtieinverter.de/, will take the initiative to switch to feedback.
3 thesis
take 16 micro-disposal with high-speed IGBT power module in small capacity photovoltaic power plants to the grid. This article describing the photovoltaic power generation and grid inverter, not only has a higher effectiveness with a small distortion of output current waveform can be run independently, and in the case of the power grid, there is bound to promote the use of vision.
沒有留言:
張貼留言