A method, comprising: for at least a first range of swing angles between an internal voltage (E S) of a source-end generator and an internal voltage (E R) of a receiving-end generator: (i) obtaining a voltage magnitude (V S) of the source-end generator; (ii) obtaining a current magnitude (I S) of the source-end generator; (iii) comparing the obtained I S with a current threshold value (I min); (iv) when the obtained I S is greater than or equal to the I min: estimating a total reactance between the source-end generator and the receiving-end generator based on recorded historical swing conditions, using which maximum magnitude of current (I max) and maximum magnitude of real power (P max) values are determined or using system topology and line parameters; estimating a first swing angle (θ) between the E S and the E R as a function of the obtained V S, the obtained I S and the estimated X; and detecting a power swing condition when a function of the estimated first swing angle (θ) exceeds a threshold value; and for at least a second range of swing angles between the E S and the E R when the obtained I S is less than the I min: determining a real power value based on the obtained V S and the obtained I S; determining a maximum magnitude of power (P max) transmitted from the source-end generator to the receiving-end generator; estimating a second swing angle (θ 1) between the E S and the E R as a function of the determined P and the determined P max; and detecting the power swing condition based on the estimated second swing angle (θ 1); and responsive to the power swing condition being detected, triggering an alarm sending a trip command to a circuit breaker to isolate the source-end generator. for at least a first range of swing angles between an internal voltage (E S) of a source-end generator and an internal voltage (E R) of a receiving-end generator: (i) obtaining a voltage magnitude (V S) of the source-end generator; (ii) obtaining a current magnitude (I S) of the source-end generator; (iii) comparing the obtained I S with a current threshold value (I min); (iv) when the obtained I S is greater than or equal to the I min: estimating a total reactance between the source-end generator and the receiving-end generator based on recorded historical swing conditions, using which maximum magnitude of current (I max) and maximum magnitude of real power (P max) values are determined or using system topology and line parameters; estimating a first swing angle (θ) between the E S and the E R as a function of the obtained V S, the obtained I S and the estimated X; and (i) obtaining a voltage magnitude (V S) of the source-end generator; (ii) obtaining a current magnitude (I S) of the source-end generator; (iii) comparing the obtained I S with a current threshold value (I min); (iv) when the obtained I S is greater than or equal to the I min: estimating a total reactance between the source-end generator and the receiving-end generator based on recorded historical swing conditions, using which maximum magnitude of current (I max) and maximum magnitude of real power (P max) values are determined or using system topology and line parameters; estimating a first swing angle (θ) between the E S and the E R as a function of the obtained V S, the obtained I S and the estimated X; and estimating a total reactance between the source-end generator and the receiving-end generator based on recorded historical swing conditions, using which maximum magnitude of current (I max) and maximum magnitude of real power (P max) values are determined or using system topology and line parameters; estimating a first swing angle (θ) between the E S and the E R as a function of the obtained V S, the obtained I S and the estimated X; and detecting a power swing condition when a function of the estimated first swing angle (θ) exceeds a threshold value; and for at least a second range of swing angles between the E S and the E R when the obtained I S is less than the I min: determining a real power value based on the obtained V S and the obtained I S; determining a maximum magnitude of power (P max) transmitted from the source-end generator to the receiving-end generator; estimating a second swing angle (θ 1) between the E S and the E R as a function of the determined P and the determined P max; and detecting the power swing condition based on the estimated second swing angle (θ 1); and determining a real power value based on the obtained V S and the obtained I S; determining a maximum magnitude of power (P max) transmitted from the source-end generator to the receiving-end generator; estimating a second swing angle (θ 1) between the E S and the E R as a function of the determined P and the determined P max; and detecting the power swing condition based on the estimated second swing angle (θ 1); and responsive to the power swing condition being detected, triggering an alarm sending a trip command to a circuit breaker to isolate the source-end generator.