It is pretty much right. Neither country took responsibility for the demand (X), and so the market wasn't aware of the demand, and therefore the generation pro

It is pretty much right. Neither country took responsibility for the demand (X), and so the market wasn't aware of the demand, and therefore the generation provided by the market was lacking X. When there is more energy being taken out of the grid than being provided, generators start to slow down. That is, the power is extracted from their rotational energy (inertia), meaning their rotational speed slows down (frequency decreases). There are mechanisms in place that fix any frequency deviations, but the assumption is that deviations in frequency are symmetrically distributed around 50 Hz (or 60 Hz for you americans). When you have consistently skewed errors (i.e. frequency always being pulled down by Kosovo), you end up with a 'time error' [0]. The time error was noticed fairly quickly (frequency and analogs to 'time error' are monitored in control rooms), but the issue was that no-one took responsibility for it and because it became a political issue it was difficult for other grid operators to step in and fix it. I'm not sure about voltage being lower in this case. Voltage is a very local phenomena, and it would be very unusual for control rooms to allow voltages to be 'lower than they should be', especially over a considerable time period. To do so they would be in violation of their grid codes. [0] https://www.nerc.com/docs/oc/rs/NERC%20Balancing%20and%20Frequency%20Control%20040520111.pdf https://www.nerc.com/docs/oc/rs/NERC%20Balancing%20and%20Fre...