A topology of DC electric springs for DC household applications

Abstract

There are two types of existing direct current (DC) electric spring (DCES), of which the one realised by alternative current electric spring has low power density because of the low-pass filter with big volume, another one is realised by DC/DC converters but too complicated. In this study, aiming at households' applications, a novel topology is proposed for DCES, using a three-port DC/DC converter with a bi-directional boost-buck converter (BBC) paralleled at one port. Critical load (CL), noncritical load (NCL) and power source are located at separate port. Besides the isolation electrically, the most important advantage is that the NCL is no longer in series with DCES, which is possibly the first attempt to change the connection type of a visual NCL with an electric spring (ES) from series to normal parallel way. With the proposed DCES, CL power is regulated stable while the fluctuations are transferred to the NCL. Meanwhile, the DCES does not provide nor absorb active power at steady-state. When the battery voltage reaches its lower or upper limits, the protection mechanism will start to ensure safe operations. The effectiveness of the proposed DCES topology and its control has been validated by simulation and experiment results.

Regulation Performance of Multiple DC Electric Springs Controlled by Distributed Cooperative System

“…Compared to the existing DCES ones, the CLP-ESU topology keeps the supply of the CL and NCL isolated from each other. This circuital layout is compliant with the traditional way of connecting loads with different requirements in a power system [12]. More broadly, it can be envisaged that each output port in the figure supplies a distinct DC bus with connecting as many CLs and NCLs as per the DCES sizing power.…”

“…More details about the phase-shift control and decoupling control of DCES with the CLP-ESU topology can be found in [12].…”

Electric Spring and Smart Load: Technology, System-Level Impact, and Opportunities

“…Besides this non-isolated topology of H-DCES for achieving the decoupling of the harmonic and DC powers, a three-port isolated topology of DCES (Fig.28) has been reported in [60] for isolating the DC power supply, NCL and CL. The circuit topology comprises a three-port isolated dual active full-bridge DC-DC converter and a bidirectional boost converter (BBC).…”

Hierarchical Control with Fast Primary Control for Multiple Single-Phase Electric Springs

“…where i Gq and i Gq represent the active and reactive components of the current i G , and the last equalities hold in quasi-stationary conditions. Equations (4) and (5) show that, under the working hypothesis of a well stabilized PCC voltage, the decoupled power control is achieved by separately controlling the two current components. The relevant control scheme is drawn in Figure 4, where K and K 0 are the decoupling compensation term and the feedforward coefficient of the grid voltage, respectively, and the current loops are closed by means of Proportional Integral (PI) regulators.…”

“…Indeed, it changes the traditional operation mode of the power system, whereby the load consumption determines the power generation, into a new one, whereby the automatic matching between power generation and load demand is implemented. Therefore, ES represents an effective solution to the large grid power fluctuations expected when RESs of solar/ wind type penetrate the grid on a large scale [3][4][5][6].…”