Yongheng Yang

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Verified

Yongheng verified their affiliation via an institutional email.

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• Ph.D. (Aalborg University), B.Eng. (Northwestern Polytechnical University)
• Professor (ZJU100) at Zhejiang University

Recently, artificial intelligence (AI) has become a promising solution to the optimization of the energy harvesting and performance of photovoltaic (PV) systems. Traditional maximum power point tracking (MPPT) algorithms have several drawbacks on tracking the global maximum power point (GMPP) under partial shading conditions (PSCs). To track the GM...

Increasing in population density has led to increased demand and competition for land space. Therefore, floating photovoltaic (FPV) systems have emerged to exploit water surfaces instead of relying on land space. FPV modules in marine settings lose their performance quickly because they are exposed to high relative humidity (RH), temperature differ...

In this paper, a large‐signal synchronisation analysis method based on saddle point characteristics is proposed to discuss the stability of the phase‐locked loop (PLL)‐based reactive current injection system. Firstly, the large‐signal model of the PLL‐based reactive current injection is established. An equilibrium point analysis shows that the PLL‐...

The escalating demand for electrical energy, coupled with the depletion of traditional energy sources, has prompted extensive research into RES for power generation. To tackle carbon emission electric vehicles are being widely adopted by many countries to battle global warming. The increasing adoption of RES and electric vehicles is leading to conc...

The large-scale integration of low-inertia converterinterfaced generations (CIGs) has reduced the power system's frequency robustness and increased the risk of frequency instability. Thus, it is imperative to allocate additional (virtual) inertia and damping in power systems to maintain and enhance frequency response. However, current research in t...

The stability of the power grid with rich renewable energy resources is increasingly challenged, as power generation is highly intermittent and also with the mix of multiple energy vectors (e.g., power to hydrogen) of distinct dynamics. Furthermore, pre-designed stability margins considering certain operating points may be narrowed under varying co...

Accurately and flexibly tracking the operating point of photovoltaic (PV) system under partial shading condition (PSC) is challenging due to the multi-peak feature of power-voltage (P-V) curve, especially with the aim of flexible power control (FPC). This paper proposes a global FPC (GFPC) method based on a direct multi-peak curve-fitting of PV sys...

Dual-active-bridge (DAB) converter with multilevel neutral-point-clamped (NPC) topology has shown potential to be a viable solution for medium-voltage DC (MVDC) systems. However, it will face a crucial challenge with regard to capacitor voltage balancing. In order to mitigate the negative effects caused by the voltage imbalance, e.g., overvoltage o...

Photovoltaic (PV) energy has been a preferable choice with the rise in global energy demand, as it is a sustainable, efficient, and cost-effective source of energy. Optimizing the power generation is necessary to fully utilize the PV system. Harvesting more power uses cascading of impedance source converters taking input from low-voltage PV arrays...

Photovoltaic (PV) emulators are designed to reproduce the exact current-voltage characteristic of a PV module or array in different ambient conditions. PV emulators are essential for power converter testing in PV systems, particularly for grid-tied inverters. Certain factors, such as real-time output and simple implementation with high accuracy, sh...

Coordinated control technology attracts increasing attention to the photovoltaic–battery energy storage (PV-BES) systems for the grid-forming (GFM) operation. However, there is an absence of a unified perspective that reviews the coordinated GFM control for PV-BES systems based on different system configurations. This paper aims to fill the gap by...

The perturb & observe (P&O) maximum power point tracking (MPPT) is widely used in photovoltaic (PV) systems due to its simplicity and reliability. To optimize the performance, a tradeoff between static and dynamic efficiencies should be made. Yet, present design methods are not efficient enough for practical use. As for the prior-art calculation-ba...

The fast growth of solar photovoltaic (PV) power generation raises the concern of grid stability due to intermittency. The traditional solution based on the broad installation of energy storage systems (ESS) is considered to be costly. Hence, the latest research focuses on the active power ramp rate control (PRRC) that decouples the heavy reliance...

Reliability Oriented Electrical Machine Systems: Topology, Design, Monitoring, Diagnostic Techniques and Control

Voltage normalization is widely used in phase-locked loops (PLLs) to keep their dynamic and stability decoupled from the grid voltage amplitude. In this paper, a complex-type voltage normalization method is proposed for three-phase PLLs. First, the performances of the PLL under the conventional voltage magnitude normalization method and the d-axis...

Multi-level dual-active-bridge (DAB) DC-DC converters offer higher voltage-blocking capability and larger stepup ratios, as well as increased number of degrees of freedom (DoFs) compared to the traditional two-level DAB converter. Thus, it has potential to be used in medium-voltage DC (MVDC) systems. However, the control complexity of the multi-lev...

This article presents an initial solution based selective harmonic elimination (SHE) method for multilevel inverter (MLI) that aims to solve SHE problem with high accuracy while significantly reducing the number of iterations. Initial SHE solution is defined as a set of initial switching angles that has less accuracy as compared to the final SHE so...

In the modern power grid, characterized by the increased penetration of power electronics and extensive utilization of renewable energy, inverter-based power plants play a pivotal role as the principal interface of renewable energy sources (RESs) and the grid. Considering the stability characteristics of grid-following (GFL) inverters when the grid...

In the modern power grid, characterized by the increased penetration of power electronics and extensive utilization of renewable energy, inverters-based power plants play a pivotal role as the principal interface of renewable energy sources (RESs) and the grid. Considering the stability characteristics of grid-following (GFL) inverters when the gri...

Decarbonization of major energy-consuming sectors is a top priority of the 2015 Paris Agreement and the Intergovernmental Panel on Climate Change (IPCC) climate change 2023 report. This has significantly challenged today's energy systems with the development of long-term sustainable energy production and storage. Perhaps one of the most promising s...

A proper thermal network model (TNM) facilitates the thermal analysis of multichip power modules, and is beneficial to reliability evaluation of power converters. However, many TNMs are struggling to provide accurate thermal analysis while maintaining acceptable computational efficiency. To address this, a TNM based on the Cauer model is proposed i...

In power systems with a high penetration of renewable energy, grid-forming (GFM) and grid-following (GFL) inverters coexist with synchronous generators (SGs). The wide-frequency-band dynamic interactions among various machines result in intricate interactions involving electromagnetic dynamics and synchronous behaviors, posing challenges for stabil...

The rising demand for electrical energy, coupled with the running down of conventional energy sources, has prompted vast research into renewable energy sources (RES) for power generation. Wind and solar photovoltaic energies are among the most critical resources, despite their susceptibility to fluctuating climatic conditions. Power electronics hav...

Speed-sensorless control (SSC) techniques enhance the overall reliability while reducing the cost, and thus become attractive in induction motors (IMs). Simplicity and flexibility are the main features that make phase-locked loop (PLL)- and frequency-locked loop (FLL)-based speed estimation schemes stand out among considerable estimation methods. H...

p>Inertia assessment is an important step for frequency stability analysis in power systems. Typically, the total inertia of all devices in the system is summed up to obtain the system inertia. However, such method may be optimistic when there are a considerable number of converter-interfaced generations (CIGs). Particularly, if the CIGs saturate u...

Junction temperature monitoring (JTM) is essential for reliability evaluation and health management for insulated-gate bipolar transistor (IGBT) modules, and thus is extensively focused on in power electronics converters. However, many JTM methods for IGBT modules are criticized for providing inaccurate junction temperature information with strong...

Phase-locked loops (PLL) are increasingly used for position and speed estimation in speed sensorless control of permanent-magnet synchronous motors (PMSMs). In this paper, the saddle point characteristic phase-portrait is developed to explore the undesirable oscillation phenomena of PLL-based position and speed estimators for speed sensorless contr...

p>Inertia assessment is of important for frequency stability analysis in power systems. Typically, the total inertia of all devices in the system is summed up to obtain the system inertia. However, the result may be optimistic when there are a considerable amount of converter-interfaced generations (CIGs). If the CIGs saturate under large disturban...

p>Inertia assessment is of important for frequency stability analysis in power systems. Typically, the total inertia of all devices in the system is summed up to obtain the system inertia. However, the result may be optimistic when there are a considerable amount of converter-interfaced generations (CIGs). If the CIGs saturate under large disturban...

Microgrids are being developed with higher penetration of renewable energy sources (RES) and utilization of power electronics. The functionality of microgrids is normally measured by two indices, stability and reliability, which are highly influenced by system configuration and generation/load mission profiles. Although system-level modeling approa...

I'm happy to share our Special Issue on Power Electronics for Converter Dominated Grid-Forming Power System, in forthcoming 2nd IEEE International Power Electronics and Application Symposium (IEEE PEAS 2023). I hope I'll see you in Guangzhou for exchanging ideas for the evolution of Converter Dominated Grid-Forming Power Systems!

Reliability is of importance for operation maintenance and cost reduction in power electronics and systems. Based on the reliability models of power devices, reliability-oriented power sharing in microgrids enforces the redistribution of power among converters to prolong the lifetime of the entire system, and droop control is typically used herein....

There are many impedance-based methods to analyze the oscillation of grid-connected converter system (GCS). However, it is difficult to answer which method is more suitable to analyze the oscillation instability of phase-locked loop (PLL). In this paper, two single-input single-output (SISO) impedance-based equivalent models were compared in terms...

A large-scale photovoltaic (PV) power plant is composed of hundreds or thousands of solar panels, which makes fault diagnosis a challenging problem due to its complexity. It is known that the PV power output characteristics dramatically change with environmental conditions. Thus, it is difficult to distinguish a short-circuit line fault from mismat...

Two-three (2/3)-level dual-active-bridge (DAB) DC-DC converter has high potential to become a promising solution for medium-voltage high-power applications. However, its switching characteristics, modeling, and optimal modulation schemes have not been comprehensively explored yet. In order to avoid voltage and current distortions, and ensure reliab...

This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values an...

Less energy consumption and more efficient use of renewables are among the sustainable energy targets of modern societies. The essential activities to be achieved under these objectives are to increase distributed generation (DG) structures’ applicability. DG systems are small-scale versions of the traditional power grid; they are supported by micr...

Power electronics is the enabling technology for the grid-integration of large-scale renewable energy generation, which provides high controllability and flexibility to energy generation, conversion, transmission, and utilization. However, power electronics also brings several challenges to the conventional power grids, e.g., reducing the system in...

Power electronic systems are facing the challenge to function more safely and reliably. Reliability-oriented power sharing is thereby employed in multi-converter systems to reduce the cost of end-of-life maintenance. One typical approach is to adaptively adjust the droop gains of the converters solely based on the accumulated damage to the power de...

This paper introduces a compensation methodology that enables the coordination of multiple DC/DC converters to mitigate the second-order voltage harmonic component in hybrid microgrids. The proposed methodology utilizes metaheuristic algorithms to prohibit circulating currents and share harmonic currents among the compensating circuits. The propose...

Conventional vector control (VC) is widely used in the voltage source converter (VSC) due to its simplicity and power decoupling ability. However, this paper reveals that the VC may result in strong active and reactive power coupling under weak AC grid conditions. The linearized relationship between the power and dq-axis currents is built. On this...

This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values an...

Large solar photovoltaic (PV) penetration using inverters in low voltage (LV) distribution networks may pose several challenges, such as reverse power flow and voltage rise situations. These challenges will eventually force grid operators to carry out grid reinforcement to ensure continued safe and reliable operations. However, smart inverters with...

Grid-connected inverters are the key part in renewable energy power generation systems. Usually, phase-locked loop (PLL) is adopted in grid-connected inverters to achieve synchronization. However, prior-art works have revealed that the negative resistance behavior in the low-frequency band caused by PLLs may lead to system instability under weak gr...

As the power system becomes more inertia-less, several issues related to stability and control reliability have emerged, provoking desynchronization phenomena, firstly at the grid-tied inverters and propagating to the entire network. Thus, in order to enhance power system reliability and widen the inverter-based distributed generators withstanding...

The complex-coefficient filter-based phase-locked loop (CCF-PLL) is widely used in state estimation for the constant frequency grid system. However, its performance under power systems with a variable frequency is generally unacceptable and related applications are consequently rare. This letter proposes an adaptive enhanced complex-coefficient fil...

In distributed power generation systems, the inherent resonance phenomena of LCL-filtered grid-connected inverter is one of the major challenges faced by the integration of renewable energy resources with the electric power grid. In this context, the capacitor current based multi-loop active damping method is employed due to lossless resonance damp...

The dynamics of nonresonant dual-active-bridge converter (DABC) are simultaneously affected by the transient modulation strategy and controller design. In general, inappropriate transient modulation strategies can lead to nonzero transient dc offsets in the inductor current and transformer’s magnetizing current, thus introducing excessive trajector...

Although power electronic converters have been the key enablers for the the integration of renewable generation, heterogeneous controllers and lower inertia increase the complexity of microgrids, more likely to cause instability. Hence, it is significant to study the stability of microgrids using prospective modeling tools such as, bode plots, Nyqu...

Unmanned aerial vehicles (UAVs) can be regarded as one of the most emerging technologies. Compared with piloted aerial vehicles, UAVs qualify for higher safety and lower cost, and they are more suitable for dangerous missions. Recently, fuel cell (FC) UAVs have obtained more and more attention due to their relatively higher energy density. However,...

Three billion people around the world live in severe energy poverty, including 1.1 billion who live completely off-grid. Providing affordable energy access to them can dramatically impact their living standard, health, education, productivity, and ability to be a part of modern society. In developing economies, the utilization of energy is also lim...

Grid frequency supports, e.g., the virtual inertia control (VIC) and the frequency damping control (FDC), of photovoltaic (PV) systems, are more demanded than ever before. To improve the frequency quality in terms of important features, i.e., the rate of change of frequency (RoCoF) and the frequency nadir, the dual-mode control has been proposed in...

In this article, a generic plug-in fractional-order multiperiodic odd harmonic repetitive control (FOMP-OHRC) scheme is proposed to provide a simple high-performance control solution to the programmable ac power sources. The proposed FOMP-OHRC scheme evolves from the plug-in multiperiodic OHRC scheme, which can take both advantages of the multiperi...

Partial shading (PS) is inevitable during the outdoor operation of photovoltaic (PV) arrays. If not addressed appropriately, PS events will significantly reduce the output power and induce other severe issues, such as hot spotting. In addition, maintenance strategies should be designed according to the specific PS patterns, which are different from...