The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper presents the capabilities and benefits of reactive power support of the nonsynchronous interconnection system, “GridLink”, in microgrid applications. This equipment provides grid interconnection using a back to back converter. Particularly, it also provides ancillary services including reactive power, spinning reserve for frequency regulation, fault mitigation, and aids in black start for...
This paper presents the stability analysis of a hybrid AC/DC power distribution system, for embedded applications, particularly for more electric aircraft. In the studied system, a balanced AC source supplies the hybrid system, and a DC distribution system feeds multi-converter controlled loads. The load converters are tightly controlled, behaving as constant power loads with low damped LC input filters...
Digital high-frequency arc welding inverter is widely used in welding areas because of its many advantages such as high efficiency, small size, easy to control etc. However, with the development of high frequency of the switching, the conducted EMI generated by arc welding inverter becomes increasingly serious, especially common mode conducted EMI. Based on Digital Active EMI Filter (DAEF) controller,...
To investigate the instability issues of three-phase voltage source converters (VSCs) connected to a weak grid, this paper develops a modeling method based on the harmonic-balance approach. The nonlinear coordinate transformation in the control system would generate two sideband components. If the grid is not strong while the bandwidth of phase-locked loop (PLL) is high enough, the sideband components...
In this paper, two charging modes of battery energy storage system (BESS) for a stand-alone microgrid are analyzed. The stand-alone microgrid system consists of 50kW BESS, 50kW diesel generator (DG) and controllable loads, where BESS is composed of 115kWh battery bank and 50kW DC-AC inverter. The operation modes of the stand-alone microgrid system are divided into four modes, and BESS is connected...
Increasing the penetration of distributed renewable sources, including photovoltaic (PV) sources, poses technical challenges for grid management. The grid has been optimized over decades to rely upon large centralized power plants with well-established feedback controls, but now non-dispatchable, renewable sources are displacing these controllable generators. By programming autonomous functionality...
For the grid-connected voltage source inverters, the feedforward scheme of grid voltage is commonly adopted to mitigate the current distortion caused by grid background voltages harmonics. This paper investigates the grid-voltage-feedforward active damping for grid connected inverter with LCL filter. It reveals that proportional feedforward control can not only fulfill the mitigation of grid disturbance,...
Voltage feed-forward control (VFFC) is widely used due to its good low-frequency-harmonics suppression and easy implementation, however, it will worsen system stability under the weak grid condition. In this paper, the stability of single-phase grid-connected inverter with VFFC is studied based on impedance analysis method. With this method, the instability mechanism and the unstable area caused by...
To study the clustered voltage balancing mechanism for cascaded H-bridge STATCOM, the active power from the grid is decomposed of by using positive and negative sequences in dq frame. Based on the detailed analysis, portion of clustered active power generated by negative-sequence voltages and currents, referred as negative-sequence clustered active power (NCAP), can redistribute the active power among...
To address the instability issue in renewable systems of a radial-line structure with multiple current-controlled interface inverters, this paper proposes a practical stability criterion to easily analyze the system stability and a controller parameter design method to guarantee stable system operation with good oscillation damping performance. The proposed impedance-based sufficient stability criterion...
By modeling the typical electromechanical transient of grid-tied PWM inverters, this paper firstly proves that PWM inverters and Rotational Synchronous Generators (RSGs) are similar in physical mechanism and equivalent in mathematical model, and the concept of Static Synchronous Generator (SSG) is thereby developed. Furthermore, the rationality and feasibility of migrating the concepts, tools and...
Current trends in power distribution systems are focused on distributed architectures instead of centralized approach. Distributed architectures are more complex since a network of power electronic converters is required to distribute power with appropriate performance. One of the main issues deals with the control loop design of the converters when they are loaded by other converters downstream....
A real-time hardware testbed (HTB) has been constructed to emulate the power system by modular regenerative converters. This allows system realistic testing and demonstration with the true measurement, communication, and control. However, the size of the system that can be emulated by the HTB is limited, and certain phenomena are not easy or not needed to be modeled in the HTB. A hybrid emulation...
Synchronverter is an inverter equipped with proper control algorithms to mimic the operation of a synchronous generator. In this paper, a stability analysis of the synchronverter is performed and it is shown that the synchronverter's stability margins are directly related to the presence of an external passive resistance. This resistance compromises its efficiency as much as five percent in a typical...
DC microgrids are becoming popular in distribution systems based on its higher reliability and system efficiency. DC bus signal (DBS) control as a common control strategy was widely used in dc microgrids, in which, control mode of each power electronic converter is triggered by monitoring the dc voltage variation to keep the power balance of the dc microgrid. Most of the dc microgrid stability analysis...
Harmonic Quasi Resonant (HQR) control is widely adopted to suppress the harmonic currents for LCL-filtered inverters in stiff grid. However, inverters with HQR control may observe instability when the point of the common coupling (PCC) behaves uncertain impedance or the HQR control frequency is out of the bandwidth of the system control loop. Besides, it could not effectively eliminate the harmonics...
An advanced service provided by the Smart Transformer (ST) is the decoupling between the Medium Voltage (MV) and Low Voltage (LV) grids. In the LV side, the ST can modify the waveform's frequency in order to interact with the droop controllers of the local generators to control the power demand among the sources without affecting the MV grid. However, most of the existing controllers for power converters...
Future U.S. Navy ships will require power systems that meet more stringent agility, efficiency, scalability, controllability and resiliency requirements. Modularity and the ability to interconnect power systems having their own energy storage, generation, and loads is an enabling capability. To aid in the design of power system controls, much of what has been learned from advances in the control of...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.