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This article introduces a new scheme for suburban renewable energies, hydrogen plant, and logistics (SRE-HP-LC) integration scheme and dispatching. The objective of the proposed SRE-HP-LC integration scheme aims at coordinating the operation of renewable energies, hydrogen production, and storage and logistic transportation. In order to take advantages of various energy conversion techniques to enhance the energy utilization rate and improves the financial revenue of the integration scheme, a completed dispatching and operating scheme for the proposed SRE-HP-LC integration scheme is introduced in the scheme stage. A multiple-demand response objective function is developed in the operation stage to coordinate the hydrogen energy usage in the SRE-HP-LC integration scheme. The proposed SRE-HP-LC integration scheme considers the uncertainties of renewable energy output and truck demand so that it improves the revenue of every component in the integration scheme. Case studies on a general integration system verify the effectiveness and economic value of the proposed SRE-HP-LC integration scheme. [ABSTRACT FROM AUTHOR]

Urban power grids are facing many operational and expansion challenges to meet further demand growth and increased reliability requirements. Advanced transmission technologies have been considered by the electric utilities to effectively increase the utilization of existing infrastructure and operational flexibility. The focus of this paper is on VSC-HVDC technologies for urban power grid enhancement and modernization. First, a potential technical scheme is proposed for converting an existing AC circuit to DC operation, which could boost the power transfer capability of the critical transmission corridor and increase network operational flexibility. Second, this paper proposes three operation modes for the VSC-HVDC interties in urban power grids corresponding to normal, emergency and island operating conditions, respectively. An integrated, adaptive emergency control strategy (AEC) is proposed that can enable adaptive power flow responses of the VSC-HVDC intertie under varying system operating conditions and critical contingencies. The flexibility and effectiveness of the proposed operational principles of urban VSC-HVDC intertie and the corresponding control strategies are verified in PSCAD/EMTDC using a realistic urban power grid in China. [ABSTRACT FROM AUTHOR]

• An optimal combined operation scheme for pump storage and wind-pv system is proposed. • Real-time coordinated control enabling automatic dispatch of the pump storage. • The power production fluctuations of wind-pv system is reduced with proposed scheme. • The revenue of hydro wind-pv system is significantly improved with proposed scheme. Because of the steady increase of wind and solar capacity installations in recent years, the goal of the Paris Agreement is expected to be reached. However, due to the intermittent characteristics of renewable generation, challenges are presented for the power grid to operate reliably and economically under the high uncertainty of wind and solar power productions. Sufficient responsive reserves must be available for the power grid to maintain the balance between the supply and demand. To be fair to the market participants, the renewable generation companies should pay for the received grid ancillary services. In this paper, an optimal combined operation scheme is proposed for pumped storage hydro and hybrid wind-photovoltaic complementary power generation system interconnected by a Voltage Source Converter-based multi-terminal HVDC system. The optimal combined operation scheme has two real-time control functions. The pumped storage hydro control function enables automatic dispatch of the pumped storage hydro to effectively suppress or compensate for the output deviations of wind and solar generation from the forecasted production; and the output control function is able to distribute the non-compensated production surplus or deficit to different ac systems based on the market regulating service prices. A Case study is provided to demonstrate the improved power generation profile and reduced revenue losses of the pumped storage hydro and hybrid wind-photovoltaic complementary power generation system. [ABSTRACT FROM AUTHOR]

With the development of urban economy and the growing integration of renewable energy, there are increasing challenges on the urban power grid. Due to the transmission stress and short-circuit current limitation, the traditional urban power grid cannot satisfy the new requirements. Multivoltage-level dc grid (MDCG) is an alternative approach to the urban power grid upgrade. This paper presents an MDCG topology, which can be used in a future urban power grid. Three operation modes of an urban MDCG are proposed: auto operation mode, power-limited operation mode, and stand-alone operation mode. The auto operation mode is the normal one for urban MDCG. The power-limited operation mode is designed to keep the capability to support urban high voltage ac transmission grid in emergencies. The stand-alone operation mode is used to keep stability in case the dc–dc converter system outage occurs. The combination control of three operation modes is put forward to enhance the reliability of urban MDCG in various operating conditions. The simulation results show that the proposed operation modes and combination control are effective and have good performance. [ABSTRACT FROM PUBLISHER]

• A back-up frequency response control based on the HVDC link is proposed. • To avoid a second frequency drop, a frequency compensation control is proposed. • A response distribution optimization strategy is proposed to reduce the event cost. With the increasing penetration of wind energy into power grids, the frequency regulation capability of the system tends to deteriorate. Wind generators (WGs) could provide fast frequency response when the system suffers from disturbances. However, due to the randomness and intermittence of WG, its emergency support is not stable. The spinning reserves of the asynchronous power grids can be shared through the high voltage direct current (HVDC) links. Under a large disturbance, the HVDC link could provide fast frequency response support to maintain the operating frequency of the disturbed power grid within a secure range. In this paper, a frequency secure control strategy is proposed for the HVDC link connected to a power system with high penetration of wind energy. The proposed frequency secure control strategy has three control functions: (1) back-up frequency response control, (2) frequency compensation control, and (3) response distribution optimization. The objective of this control strategy is to improve the synthetic frequency response performance of the system under severe frequency disturbance while avoiding possible subsequent frequency drop caused by rotor speed recovery of wind turbines. Besides, the cost of ancillary service for obtaining frequency response support from interconnected power systems could be reduced. Simulation verifications are conducted on a reduced equivalent ERCOT system which is interconnected to equivalent Western and Eastern Interconnections by HVDC links. The simulation results verify the feasibility and effectiveness of the proposed frequency secure control strategy. [ABSTRACT FROM AUTHOR]

• The framework combines a cloud-edge-end structure to break the information barriers of multi-source measured data. • The method executes different strategies according to voltage levels based on interaction of edge computing is proposed. • Harmonic source identification and evaluation are achieved through the multi-level interaction of edge computing. • TVE, CMHSE and HHSE method for cloud-edge-end collaborative computing strategy are developed into the system. With the increase of power electronic devices such as distributed renewable energies, energy storage, and flexible loads, the disturbance sources are rapidly raised and distributed in multiple voltage levels in the distributed network. The harmonics they produce are random and uncertain, and the massive amounts of data propose high demands on server computing capability, which restrict harmonic sources evaluation and significantly influence the judgments of the power quality in the distribution network. In order to improve the power quality and the harmonic source evaluation function of the distribution network, in this paper, a framework for multi-harmonic source identification and evaluation based on cloud-edge-end collaboration is proposed. Firstly, based on the analysis of the functional requirements harmonic sources evaluation in multiple voltage levels, a novel framework of cloud-edge-end collaboration is proposed. Secondly, the cloud-edge-end collaborative harmonic sources evaluation method which executes different service strategies according to voltage levels and grid operation based on the multi-level interaction of edge computing is proposed. Further, the working principle of the proposed novel framework with multiple evaluation methods including the dominant harmonic source identification, concentrated multiple harmonic sources evaluation (CMHSE) and hierarchical harmonic sources evaluation (HHSE) is described in detail in order to show the completed work processes of the proposed framework. Finally, the performance of the proposed method is verified based on the real data measured from different realistic urban power grids in China. The proposed method can effectively evaluate harmonic contributions in distribution systems and in turn provide a basis for harmonic mitigation measures. [ABSTRACT FROM AUTHOR]

With the increasing demand of electricity, the development of the urban power grid has drawn a lot of attention in China. In order to focus on the analysis of an urban power grid, the remaining part of the large-scale power grid used is to be reduced. The accuracy of the equivalence is key to urban power grid research. In this paper, a multistep dynamic equivalent method based on district dividing is proposed. Based on the electrical distance, voltage level, and geographic location, the external system is divided into outer layer, inner layer, and buffer subsystem. Each district is separately reduced by different methods. The proposed technique is illustrated by a real large-scale power grid in the south of China. [ABSTRACT FROM PUBLISHER]