Evaluation of HVDC system's impact and quantification of synchronous compensation for distance protection

Abstract

This paper presents a comprehensive evaluation of the HVDC system's impact on distance protection via systematic and realistic experimental tests, along with theoretical analysis of the root causes of the identified compromised protection performance. A methodology for quantifying the impact of Synchronous Compensation (SC) in supporting the distance protection operation is also established. In this work, the performance of two widely used physical distance protection relays have been evaluated using a realistic Hardware'In'the'Loop (HIL) testing environment, where a total of 480 cases have been tested under a wide range of system scenarios. Representative cases with compromised protection performance are selected, where issues of under/over'reach, faulted phase selection and impedance measurement are identified and analysed. Furthermore, a method for quantifying the required SC level to address the under/over'reach issues resulting from HVDC systems is presented. The method establishes the relationship between the angle difference of the two'end fault current infeeds of the protected line and the SC level. Based on this relationship, the required SC capacity to constrain the angle difference within a targeted limit can be estimated, which offers a useful tool for system operators to appropriately size the SC's capacity with additional valuable insights from the distance protection perspective.

Evaluation of travelling wave protection performance in converter-dominated networks

“…Therefore, the injection of negative-sequence current has been formally suggested in some newly published international standards, such as in the IEEE Std 2800-2022 [17]. Considering the future trend of the negative-sequence current injection and the possibility of different converter operating modes, a flexible controller reported in [4] is implemented in the developed converter model to realise different converter operating modes including the balanced current mode, constant active power mode and constant reactive power mode, and thus allow the investigation of the converter controller's impact on the protection scheme under test.…”

“…In this section, three different control strategies in [4], including the balanced current (BI) mode to inject balanced currents, constant active power (CP) mode to suppress the ripples on the injected active power and constant reactive power (CQ) mode to suppress the ripples on the delivered reactive power, are implemented to the connected CBR in Fig. 5.…”

Review and Evaluation of Control-Based Protection Solutions for Converter-Dominated Power Systems

“…3. Two cases are investigated: 1) the fault infeed from one end is a GFL converter that uses the dual-sequence current control strategy [25], which allows the independent control of the positive-sequence and negativesequence components; 2) the converter control is replaced by the virtual impedance-based GFM control scheme [15], which aims to emulate voltage source behaviour by virtually controlling the source impedance of GFM converter. It should be noted that, the aforementioned cases can be classified into the symmetrical component control-based protection.…”

“…Therefore, Short Circuit Ratio (SCR) of the test system is equal to 3. In general, it can be regard as a weak system [25], so that the above cases are conduced to evaluate converters' performance in weak power systems. The test system as shown in Fig.…”

Rethinking Power System Protection Analysis and Setting: Introducing Bayesian Analysis and Decision Theory

“…Consequently, protection function maloperations are likely to occur in a system with a large share of GCCs given that these either cannot (e.g., they cannot supply fault currents with the same magnitudes as synchronous machines) or do not deliver such fault currents (e.g, they can actively control the angle of injected currents or suppress negative sequence components, see for instance [15]). Given the non-linear nature of fault current injections, protection function maloperations in systems with a large share of GCCs are often case-and system-specific, e.g., as shown in [16], [17] for distance protections or [18] for negative sequence protection.…”