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Current control method for photovoltaic grid-connected inverter

A current control and inverter technology, applied in the field of improved current control of photovoltaic grid-connected inverters, optimal control of photovoltaic grid-connected inverters, can solve grid voltage distortion and harmonic interference, gain limitation, open loop Small gain and other issues

Active Publication Date: 2014-09-10
GUANGZHOU INST OF ENERGY CONVERSION - CHINESE ACAD OF SCI
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  • Application Information

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Problems solved by technology

In order to ensure the stability of the system, the gain of the PID regulator is limited, the open-loop gain of the system in the low frequency band is small, and the system's ability to suppress the steady-state error and harmonics of the output current is not good.
At the same time, this method is also susceptible to grid voltage distortion and harmonic interference

Method used

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  • Current control method for photovoltaic grid-connected inverter
  • Current control method for photovoltaic grid-connected inverter
  • Current control method for photovoltaic grid-connected inverter

Examples

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Embodiment

[0038] figure 1 The topology and control diagram of a typical single-phase bipolar non-isolated photovoltaic grid-connected inverter are given. The pre-stage Boost circuit charges the bus capacitor to realize the DC bus boost and the MPPT control function of the photovoltaic module. The post-stage inverter part adopts double-loop control to realize power conversion. Double-loop control refers to the voltage outer loop for bus capacitor voltage stabilization and the current inner loop for power output. u b_ref Select according to the withstand voltage of the bus capacitor and actual needs, generally 400V. The voltage outer loop bus voltage regulator adopts PI control, which can realize the U b_ref No static error tracking; the current feedback signal is sinusoidal, and the current inner loop adopts P control.

[0039] Please refer to figure 2 As shown, the photovoltaic grid-connected inverter current control method includes the following steps:

[0040] S10. Mains volta...

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Abstract

The invention discloses an improved current loop control method for a photovoltaic grid-connected inverter, and belongs to the technical field of solar photovoltaic power generation. The method comprises the following steps that: a voltage feedforward control quantity u1 is obtained through commercial electricity voltage feedforward; 2, a current error [delta]i is obtained through a voltage outer loop control structure; 3, the current error [delta]i is segmented for forming a plurality of current error segments, each current error segment adopts different gains, and a current equivalent voltage duty ratio control quantity u2 is obtained after the current passes through a current inner loop control structure adopting a controller P; and 4, a command value u_order of a switch comparison register is obtained. The control method provided by the invention has the advantages that the realization is simple; complicated integral and differential coefficient setting is not needed; the introduction of virtual orthogonal signals is not needed; time-consuming dp coordinate transformation is avoided; meanwhile, the output current distortion can be effectively reduced; and the resistance capability on electricity grid distortion and harmonic interference is enhanced.

Description

technical field [0001] The invention relates to the optimal control of a photovoltaic grid-connected inverter, and provides an improved current control method of a photovoltaic grid-connected inverter, which belongs to the field of solar photovoltaic power generation. Background technique [0002] Solar energy is currently one of the cleanest, most realistic, and most promising renewable energy sources for large-scale development and utilization in the world. Solar photovoltaic grid-connected power generation is the main trend of solar photovoltaic utilization, and it is bound to develop rapidly. Photovoltaic grid-connected inverter is the core of photovoltaic power generation system, and it is the interface circuit between new energy power generation, micro-grid, etc. and large power grid. The quality control of its incoming current is one of the key technologies. Photovoltaic grid-connected inverters usually include a PWM modulation inverter topology based on high-frequen...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02M7/48
CPCY02E10/563Y02A30/60Y02E10/56
Inventor 戴志威舒杰吴昌宏王浩张继元吴志锋
Owner GUANGZHOU INST OF ENERGY CONVERSION - CHINESE ACAD OF SCI
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