Lecture 15 - Electric Utility Integration and Value Assessment

Lecture 15 - Electric Utility Integration and Value Assessment

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Unformatted text preview: 4/11/11 1 ECE 4364/5374G-15 (c) Saifur Rahman 1 Professor Saifur Rahman Electrical & Computer Engineering Dept. Virginia Tech ECE 4364/5374G: Alternate Energy Systems Lecture 15: Electric Utility Integration and Value Assessment ECE 4364/5374G-15 (c) Saifur Rahman 2 Chapter 15 Electric Ulity Integraon The renewable and advanced technologies discussed so far are candidates for grid interconnection. However, there are some special needs and characteristics that have to be taken into account. 4/11/11 2 ECE 4364/5374G-15 (c) Saifur Rahman 3 U1lity Interconnec1on Issues Harmonic Injection - distorts wave shape (detrimental effect on many utility loads) Impact of the PV systems' power factor on the utility system Voltage flicker disturbance from photovoltaic systems Islanding ECE 4364/5374G-15 (c) Saifur Rahman 4 Harmonics Higher frequency signal super-imposed on power lines. The 3 rd , 5 th , 7 th and 9 th are most common harmonics. Harmonics affect equipment that are dependent on zero crossing of the AC waveform for internal switching. Harmonics cause over-heating and thermal breakdowns in transformers and motors. They also interfere with relaying, metering and switching functions. Current Harmonics are usually injected into utility lines. 3rd and 5th Harmonics 4/11/11 2 ECE 4364/5374G-15 (c) Saifur Rahman 3 U1lity Interconnec1on Issues Harmonic Injection - distorts wave shape (detrimental effect on many utility loads) Impact of the PV systems' power factor on the utility system Voltage flicker disturbance from photovoltaic systems Islanding ECE 4364/5374G-15 (c) Saifur Rahman 4 Harmonics Higher frequency signal super-imposed on power lines. The 3 rd , 5 th , 7 th and 9 th are most common harmonics. Harmonics affect equipment that are dependent on zero crossing of the AC waveform for internal switching. Harmonics cause over-heating and thermal breakdowns in transformers and motors. They also interfere with relaying, metering and switching functions. Current Harmonics are usually injected into utility lines. 3rd and 5th Harmonics 4/11/11 3 ECE 4364/5374G-15 (c) Saifur Rahman 5 Power Condi1oning Unit (PCU) func1ons Inversion (DC to AC), Maximum Power Tracking, Control and Safety. The PCU is turned off under the following conditions: Over-voltage Under-voltage Loss of line power ECE 4364/5374G-15 (c) Saifur Rahman 6 PCU and Harmonics Waveshaping method of the inverter section of the PCS determines the level of harmonics....
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Lecture 15 - Electric Utility Integration and Value Assessment

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