Huai-Jhe Su

Bio: Huai-Jhe Su is an academic researcher from Atomic Energy Council. The author has contributed to research in topics: Stand-alone power system & AC power. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.

Ancillary voltage control for a distribution feeder by using energy storage system in microgrid

Abstract: This paper presents ancillary voltage control for a distribution feeder by using energy storage system (ESS) in microgrid. The microgrid consists of photovoltaic, wind power, and distribution generator. The active and reactive power control, voltage and frequency droop control for the power converter of ESS are proposed to reduce microgrid impact on the distribution feeder. The voltage variation along the feeder due to change of renewable power generation is derived by executing power flow analysis. The actual voltage fluctuation on the microgrid is measured, which is used to control active and reactive power output of the power converter via energy management system in the microgrid SCADA platform. Three operation scenarios of the microgrid with ESS are tested to verify the effectiveness of the proposed control method. It is found that the power output of ESS can be well regulated to reduce voltage fluctuation on the microgid, which is complied with grid connect code to achieve better voltage control performance for the distribution feeder.

Reactive Power Management in Renewable Rich Power Grids: A Review of Grid-Codes, Renewable Generators, Support Devices, Control Strategies and Optimization Algorithms

Abstract: Power electronic converter (PEC)-interfaced renewable energy generators (REGs) are increasingly being integrated to the power grid. With the high renewable power penetration levels, one of the key power system parameters, namely reactive power, is affected, provoking steady-state voltage and dynamic/transient stability issues. Therefore, it is imperative to maintain and manage adequate reactive power reserve to ensure a stable and reliable power grid. This paper presents a comprehensive literature review on the reactive power management in renewable rich power grids. Reactive power requirements stipulated in different grid codes for REGs are summarized to assess their adequacy for future network requirements. The PEC-interfaced REGs are discussed with a special emphasis on their reactive power compensation capability and control schemes. Along with REGs, conventional reactive power support devices (e.g., capacitor banks) and PEC-interfaced reactive power support devices (e.g., static synchronous compensators) play an indispensable role in the reactive power management of renewable rich power grids, and thus their reactive power control capabilities and limitations are thoroughly reviewed in this paper. Then, various reactive power control strategies are reviewed with a special emphasis on their advantages/disadvantages. Reactive power coordination between support devices and their optimal capacity are vital for an efficient and stable management of the power grid. Accordingly, the prominent reactive power coordination and optimization algorithms are critically examined and discussed in this paper. Finally, the key issues pertinent to the reactive power management in renewable rich power grids are enlisted with some important technical recommendations for the power industry, policymakers, and academic researchers.

Optimal microgrid planning for enhancing ancillary service provision

Abstract: Microgrids have presented themselves as an effective concept to guarantee a reliable, efficient and sustainable electricity delivery during the current transition era from passive to active distribution networks. Moreover, microgrids could offer effective ancillary services (AS) to the power utility, although this will not be possible before the traditional planning and operation methodologies are updated. Hence, a probabilistic multi-objective microgrid planning (POMMP) methodology is proposed in this paper to contemplate the large number of variables, multiple objectives, and different constraints and uncertainties involved in the microgrid planning. The planning methodology is based on the optimal size and location of energy distributed resources with the goal of minimizing the mismatch power in islanded mode, while the residual power for AS provision and the investment and operation costs of the microgrid in grid-connected mode are maximized and minimized, respectively. For that purpose, probabilistic models and a true multi-objective optimization problem are implemented in the methodology. The methodology is tested in an adapted PG&E 69-bus distribution system and the non-dominated sorting genetic algorithm II (NSGA-II) optimization method and an analytic hierarchy process for decision-making are used to solve the optimization problem.

Multi-Objective Probabilistic Power Resources Planning for Microgrids with Ancillary Services Capacity

Abstract: Microgrids have become an attractive strategy to guaranty a reliable, efficient and sustainable electricity delivery to the distribution network, as well as to offer effectively ancillary services to the power utility. Therefore, special features have to be introduced to the planning methodology, while the optimization problem has also to be re-evaluated to contemplate the large number of variables, multiple objectives, and different constraints and uncertainties. Hence, a probabilistic multi-objective microgrid planning methodology based on the optimal size and location of distributed generation is proposed. In this methodology, the mismatch power in islanded mode and the annual energy losses in grid-connected mode are minimized, while the residual power for reserve provision is maximized. For that purpose, probabilistic models, distributed storage units, and constructive constraints are contemplated in the methodology. The methodology is tested in an adapted PG&E 69-bus distribution system and the NSGAII optimization method is used to solve the optimization problem.

Assessment and Control of Microgrid Impacts on Distribution Networks by Using Experimental Tests

Abstract: The main aim of this article is to assess and control impacts that a grid-tied microgrid may have on a distribution network. For this purpose, the tie-line power flow has been considered in a performance index to be minimized. In particular, three statistical indices have been compared on the microgrid operated under a classical day-ahead dispatching policy and an online optimal control strategy. The online optimization process starts from the same day-ahead dispatching policy and tries to compensate the tie-line power flow deviations from the scheduled value. For this purpose, a real-time economic dispatching algorithm based on a proportional integral derivative controller has been developed and implemented on the PrInCE Lab microgrid, located at the Polytechnic University of Bari, Bari, Italy.

Regulating power management in interconnected microgrids

Abstract: An effective regulating power management is needed in next generation interconnected microgrids to mitigate the effect of load-generation imbalance in the system. The objective of this paper is to present a two-stage regulating power management scheme in an interconnected microgrid (MG) system. First, in a day-ahead power management, the power generation set-points are determined in the individual MGs considering predicted demand and power from renewable energy sources. Second, in a real-time regulating power management, a network operator establishes a set of power flow interactions among MGs to mitigate the load-generation imbalances in MGs. These interactions are obtained using a convex multi-constraint optimization problem and a cooperative developed algorithm. A simple suboptimal greedy solution is also proposed. Numerical results demonstrate the effectiveness of the proposed real-time regulating power management in cooperation with day-ahead scheduling to reduce the system load-generation imbalance,...