Reliability assessment of PV location based on a new coordination and failure rates of protection relays to minimize indices energy

Protection relays are crucial to analyzing how photovoltaic (PV) systems improve network dependability during disturbances. Thus, an in-depth analysis is performed to determine how PV integration affects the nominal load current of the medium voltage (MV) line. This analysis helps determine appropriate pickup currents in overcurrent (OC) relay protection systems. This requires careful relay operation times, exact estimations of the highest and lowest short-circuit values, and methods to mitigate the impact of interfacing inverters across PV penetration levels. In energy indices calculation, a final study proposes new restrictions coordination between OC relay and PV in-feed current protection. A method for computing the energy not supplied (ENS) metric takes into account the harmonized operation of principal and secondary OC relays and PV system current-based protective actions at their connection points. The simulations have shown that the proposed method is better at lowering the ENS's yearly value than the standard method, which includes PV. Consequently, the reliability indices will reach the minimum value and to showcase the efficacy and precision of the provided analysis, the ETAP software program is utilized as a demonstrative tool. Without failure rate modification, the EENS is 144643.500 MWh/year, and the ENS is 478.155 h/year. After PV integration, bus failure rates dropped 35% compared to the relay coordination situation. As a result, the EENS equals 158435.755 MWh/year, and the suggested method lowers the ENS's annual weight by 47.5% compared to the conventional way.

继电保护装置（Protection relays）对于分析光伏（PV，photovoltaic）系统在电网扰动期间如何提升电网可靠性至关重要。为此，本研究开展了深入分析，以明确光伏并网对中压（MV，medium voltage）线路额定负载电流的影响，该分析可为过电流（OC，overcurrent）继电保护系统的整定电流选取提供依据。此项分析需精准控制继电保护动作时限、准确估算最大与最小短路电流值，并提出缓解不同光伏渗透率下并网逆变器接入影响的方法。在能源指标计算环节，本研究最终提出了过电流继电保护与光伏馈入电流保护之间的新型整定配合方案。所提出的未供电电量（ENS，energy not supplied）指标计算方法，兼顾了主、后备过电流继电保护装置的协调动作，以及光伏系统在并网节点处基于电流的保护动作逻辑。仿真结果表明，相较于包含光伏系统的传统方案，所提方法可更有效地降低未供电电量的年度数值，由此电网可靠性指标将降至最低。为验证所提分析方法的有效性与精准性，本研究采用ETAP软件作为演示工具。未对母线故障率进行修正的场景下，预期未供电电量（EENS，Expected Energy Not Supplied）为144643.500 MWh/年，未供电时长（ENS）为478.155 h/年。光伏并网后，母线故障率较传统继电保护整定配合场景下降35%。此时，预期未供电电量升至158435.755 MWh/年，而所提方案较传统方法将未供电电量的年度权重降低了47.5%。